6424 lines
186 KiB
C
6424 lines
186 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/bpf.h>
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#include <linux/bpf_verifier.h>
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#include <linux/filter.h>
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#include <net/netlink.h>
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#include <linux/file.h>
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#include <linux/vmalloc.h>
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#include <linux/stringify.h>
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#include <linux/bsearch.h>
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#include <linux/sort.h>
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#include <linux/perf_event.h>
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#include "disasm.h"
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static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
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#define BPF_PROG_TYPE(_id, _name) \
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[_id] = & _name ## _verifier_ops,
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#define BPF_MAP_TYPE(_id, _ops)
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#include <linux/bpf_types.h>
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#undef BPF_PROG_TYPE
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#undef BPF_MAP_TYPE
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};
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/* bpf_check() is a static code analyzer that walks eBPF program
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* instruction by instruction and updates register/stack state.
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* All paths of conditional branches are analyzed until 'bpf_exit' insn.
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*
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* The first pass is depth-first-search to check that the program is a DAG.
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* It rejects the following programs:
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* - larger than BPF_MAXINSNS insns
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* - if loop is present (detected via back-edge)
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* - unreachable insns exist (shouldn't be a forest. program = one function)
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* - out of bounds or malformed jumps
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* The second pass is all possible path descent from the 1st insn.
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* Since it's analyzing all pathes through the program, the length of the
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* analysis is limited to 64k insn, which may be hit even if total number of
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* insn is less then 4K, but there are too many branches that change stack/regs.
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* Number of 'branches to be analyzed' is limited to 1k
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*
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* On entry to each instruction, each register has a type, and the instruction
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* changes the types of the registers depending on instruction semantics.
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* If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
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* copied to R1.
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*
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* All registers are 64-bit.
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* R0 - return register
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* R1-R5 argument passing registers
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* R6-R9 callee saved registers
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* R10 - frame pointer read-only
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*
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* At the start of BPF program the register R1 contains a pointer to bpf_context
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* and has type PTR_TO_CTX.
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*
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* Verifier tracks arithmetic operations on pointers in case:
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* BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
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* BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
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* 1st insn copies R10 (which has FRAME_PTR) type into R1
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* and 2nd arithmetic instruction is pattern matched to recognize
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* that it wants to construct a pointer to some element within stack.
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* So after 2nd insn, the register R1 has type PTR_TO_STACK
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* (and -20 constant is saved for further stack bounds checking).
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* Meaning that this reg is a pointer to stack plus known immediate constant.
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*
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* Most of the time the registers have SCALAR_VALUE type, which
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* means the register has some value, but it's not a valid pointer.
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* (like pointer plus pointer becomes SCALAR_VALUE type)
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*
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* When verifier sees load or store instructions the type of base register
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* can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK. These are three pointer
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* types recognized by check_mem_access() function.
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*
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* PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
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* and the range of [ptr, ptr + map's value_size) is accessible.
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*
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* registers used to pass values to function calls are checked against
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* function argument constraints.
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*
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* ARG_PTR_TO_MAP_KEY is one of such argument constraints.
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* It means that the register type passed to this function must be
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* PTR_TO_STACK and it will be used inside the function as
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* 'pointer to map element key'
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*
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* For example the argument constraints for bpf_map_lookup_elem():
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* .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
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* .arg1_type = ARG_CONST_MAP_PTR,
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* .arg2_type = ARG_PTR_TO_MAP_KEY,
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*
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* ret_type says that this function returns 'pointer to map elem value or null'
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* function expects 1st argument to be a const pointer to 'struct bpf_map' and
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* 2nd argument should be a pointer to stack, which will be used inside
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* the helper function as a pointer to map element key.
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*
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* On the kernel side the helper function looks like:
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* u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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* {
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* struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
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* void *key = (void *) (unsigned long) r2;
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* void *value;
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*
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* here kernel can access 'key' and 'map' pointers safely, knowing that
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* [key, key + map->key_size) bytes are valid and were initialized on
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* the stack of eBPF program.
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* }
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*
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* Corresponding eBPF program may look like:
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* BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
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* BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
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* BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
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* BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
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* here verifier looks at prototype of map_lookup_elem() and sees:
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* .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
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* Now verifier knows that this map has key of R1->map_ptr->key_size bytes
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*
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* Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
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* Now verifier checks that [R2, R2 + map's key_size) are within stack limits
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* and were initialized prior to this call.
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* If it's ok, then verifier allows this BPF_CALL insn and looks at
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* .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
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* R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
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* returns ether pointer to map value or NULL.
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*
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* When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
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* insn, the register holding that pointer in the true branch changes state to
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* PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
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* branch. See check_cond_jmp_op().
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*
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* After the call R0 is set to return type of the function and registers R1-R5
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* are set to NOT_INIT to indicate that they are no longer readable.
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*/
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/* verifier_state + insn_idx are pushed to stack when branch is encountered */
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struct bpf_verifier_stack_elem {
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/* verifer state is 'st'
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* before processing instruction 'insn_idx'
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* and after processing instruction 'prev_insn_idx'
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*/
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struct bpf_verifier_state st;
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int insn_idx;
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int prev_insn_idx;
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struct bpf_verifier_stack_elem *next;
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};
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#define BPF_COMPLEXITY_LIMIT_INSNS 131072
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#define BPF_COMPLEXITY_LIMIT_STACK 1024
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#define BPF_COMPLEXITY_LIMIT_STATES 64
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#define BPF_MAP_PTR_UNPRIV 1UL
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#define BPF_MAP_PTR_POISON ((void *)((0xeB9FUL << 1) + \
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POISON_POINTER_DELTA))
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#define BPF_MAP_PTR(X) ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))
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static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
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{
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return BPF_MAP_PTR(aux->map_state) == BPF_MAP_PTR_POISON;
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}
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static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
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{
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return aux->map_state & BPF_MAP_PTR_UNPRIV;
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}
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static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
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const struct bpf_map *map, bool unpriv)
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{
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BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON & BPF_MAP_PTR_UNPRIV);
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unpriv |= bpf_map_ptr_unpriv(aux);
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aux->map_state = (unsigned long)map |
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(unpriv ? BPF_MAP_PTR_UNPRIV : 0UL);
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}
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struct bpf_call_arg_meta {
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struct bpf_map *map_ptr;
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bool raw_mode;
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bool pkt_access;
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int regno;
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int access_size;
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u64 msize_max_value;
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};
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static DEFINE_MUTEX(bpf_verifier_lock);
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void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
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va_list args)
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{
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unsigned int n;
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n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);
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WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
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"verifier log line truncated - local buffer too short\n");
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n = min(log->len_total - log->len_used - 1, n);
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log->kbuf[n] = '\0';
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if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1))
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log->len_used += n;
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else
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log->ubuf = NULL;
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}
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/* log_level controls verbosity level of eBPF verifier.
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* bpf_verifier_log_write() is used to dump the verification trace to the log,
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* so the user can figure out what's wrong with the program
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*/
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__printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
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const char *fmt, ...)
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{
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va_list args;
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if (!bpf_verifier_log_needed(&env->log))
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return;
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va_start(args, fmt);
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bpf_verifier_vlog(&env->log, fmt, args);
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va_end(args);
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}
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EXPORT_SYMBOL_GPL(bpf_verifier_log_write);
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__printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
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{
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struct bpf_verifier_env *env = private_data;
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va_list args;
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if (!bpf_verifier_log_needed(&env->log))
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return;
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va_start(args, fmt);
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bpf_verifier_vlog(&env->log, fmt, args);
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va_end(args);
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}
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static bool type_is_pkt_pointer(enum bpf_reg_type type)
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{
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return type == PTR_TO_PACKET ||
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type == PTR_TO_PACKET_META;
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}
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/* string representation of 'enum bpf_reg_type' */
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static const char * const reg_type_str[] = {
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[NOT_INIT] = "?",
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[SCALAR_VALUE] = "inv",
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[PTR_TO_CTX] = "ctx",
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[CONST_PTR_TO_MAP] = "map_ptr",
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[PTR_TO_MAP_VALUE] = "map_value",
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[PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
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[PTR_TO_STACK] = "fp",
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[PTR_TO_PACKET] = "pkt",
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[PTR_TO_PACKET_META] = "pkt_meta",
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[PTR_TO_PACKET_END] = "pkt_end",
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};
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static void print_liveness(struct bpf_verifier_env *env,
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enum bpf_reg_liveness live)
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{
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if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN))
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verbose(env, "_");
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if (live & REG_LIVE_READ)
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verbose(env, "r");
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if (live & REG_LIVE_WRITTEN)
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verbose(env, "w");
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}
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static struct bpf_func_state *func(struct bpf_verifier_env *env,
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const struct bpf_reg_state *reg)
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{
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struct bpf_verifier_state *cur = env->cur_state;
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return cur->frame[reg->frameno];
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}
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static void print_verifier_state(struct bpf_verifier_env *env,
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const struct bpf_func_state *state)
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{
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const struct bpf_reg_state *reg;
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enum bpf_reg_type t;
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int i;
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if (state->frameno)
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verbose(env, " frame%d:", state->frameno);
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for (i = 0; i < MAX_BPF_REG; i++) {
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reg = &state->regs[i];
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t = reg->type;
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if (t == NOT_INIT)
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continue;
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verbose(env, " R%d", i);
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print_liveness(env, reg->live);
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verbose(env, "=%s", reg_type_str[t]);
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if ((t == SCALAR_VALUE || t == PTR_TO_STACK) &&
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tnum_is_const(reg->var_off)) {
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/* reg->off should be 0 for SCALAR_VALUE */
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verbose(env, "%lld", reg->var_off.value + reg->off);
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if (t == PTR_TO_STACK)
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verbose(env, ",call_%d", func(env, reg)->callsite);
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} else {
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verbose(env, "(id=%d", reg->id);
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if (t != SCALAR_VALUE)
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verbose(env, ",off=%d", reg->off);
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if (type_is_pkt_pointer(t))
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verbose(env, ",r=%d", reg->range);
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else if (t == CONST_PTR_TO_MAP ||
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t == PTR_TO_MAP_VALUE ||
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t == PTR_TO_MAP_VALUE_OR_NULL)
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verbose(env, ",ks=%d,vs=%d",
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reg->map_ptr->key_size,
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reg->map_ptr->value_size);
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if (tnum_is_const(reg->var_off)) {
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/* Typically an immediate SCALAR_VALUE, but
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* could be a pointer whose offset is too big
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* for reg->off
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*/
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verbose(env, ",imm=%llx", reg->var_off.value);
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} else {
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if (reg->smin_value != reg->umin_value &&
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reg->smin_value != S64_MIN)
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verbose(env, ",smin_value=%lld",
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(long long)reg->smin_value);
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if (reg->smax_value != reg->umax_value &&
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reg->smax_value != S64_MAX)
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verbose(env, ",smax_value=%lld",
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(long long)reg->smax_value);
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if (reg->umin_value != 0)
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verbose(env, ",umin_value=%llu",
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(unsigned long long)reg->umin_value);
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if (reg->umax_value != U64_MAX)
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verbose(env, ",umax_value=%llu",
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(unsigned long long)reg->umax_value);
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if (!tnum_is_unknown(reg->var_off)) {
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char tn_buf[48];
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tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
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verbose(env, ",var_off=%s", tn_buf);
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}
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}
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verbose(env, ")");
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}
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}
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for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
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if (state->stack[i].slot_type[0] == STACK_SPILL) {
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verbose(env, " fp%d",
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(-i - 1) * BPF_REG_SIZE);
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print_liveness(env, state->stack[i].spilled_ptr.live);
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verbose(env, "=%s",
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reg_type_str[state->stack[i].spilled_ptr.type]);
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}
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if (state->stack[i].slot_type[0] == STACK_ZERO)
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verbose(env, " fp%d=0", (-i - 1) * BPF_REG_SIZE);
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}
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verbose(env, "\n");
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}
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static int copy_stack_state(struct bpf_func_state *dst,
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const struct bpf_func_state *src)
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{
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if (!src->stack)
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return 0;
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if (WARN_ON_ONCE(dst->allocated_stack < src->allocated_stack)) {
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/* internal bug, make state invalid to reject the program */
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memset(dst, 0, sizeof(*dst));
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return -EFAULT;
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}
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memcpy(dst->stack, src->stack,
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sizeof(*src->stack) * (src->allocated_stack / BPF_REG_SIZE));
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return 0;
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}
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/* do_check() starts with zero-sized stack in struct bpf_verifier_state to
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* make it consume minimal amount of memory. check_stack_write() access from
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* the program calls into realloc_func_state() to grow the stack size.
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* Note there is a non-zero 'parent' pointer inside bpf_verifier_state
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* which this function copies over. It points to previous bpf_verifier_state
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* which is never reallocated
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*/
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static int realloc_func_state(struct bpf_func_state *state, int size,
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bool copy_old)
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{
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u32 old_size = state->allocated_stack;
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struct bpf_stack_state *new_stack;
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int slot = size / BPF_REG_SIZE;
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if (size <= old_size || !size) {
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if (copy_old)
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return 0;
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state->allocated_stack = slot * BPF_REG_SIZE;
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if (!size && old_size) {
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kfree(state->stack);
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state->stack = NULL;
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}
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return 0;
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}
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new_stack = kmalloc_array(slot, sizeof(struct bpf_stack_state),
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GFP_KERNEL);
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if (!new_stack)
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return -ENOMEM;
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if (copy_old) {
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if (state->stack)
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memcpy(new_stack, state->stack,
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sizeof(*new_stack) * (old_size / BPF_REG_SIZE));
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memset(new_stack + old_size / BPF_REG_SIZE, 0,
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sizeof(*new_stack) * (size - old_size) / BPF_REG_SIZE);
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}
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state->allocated_stack = slot * BPF_REG_SIZE;
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kfree(state->stack);
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state->stack = new_stack;
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return 0;
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}
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static void free_func_state(struct bpf_func_state *state)
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{
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if (!state)
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return;
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kfree(state->stack);
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kfree(state);
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}
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static void free_verifier_state(struct bpf_verifier_state *state,
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bool free_self)
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{
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int i;
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for (i = 0; i <= state->curframe; i++) {
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free_func_state(state->frame[i]);
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state->frame[i] = NULL;
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}
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if (free_self)
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kfree(state);
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}
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/* copy verifier state from src to dst growing dst stack space
|
|
* when necessary to accommodate larger src stack
|
|
*/
|
|
static int copy_func_state(struct bpf_func_state *dst,
|
|
const struct bpf_func_state *src)
|
|
{
|
|
int err;
|
|
|
|
err = realloc_func_state(dst, src->allocated_stack, false);
|
|
if (err)
|
|
return err;
|
|
memcpy(dst, src, offsetof(struct bpf_func_state, allocated_stack));
|
|
return copy_stack_state(dst, src);
|
|
}
|
|
|
|
static int copy_verifier_state(struct bpf_verifier_state *dst_state,
|
|
const struct bpf_verifier_state *src)
|
|
{
|
|
struct bpf_func_state *dst;
|
|
int i, err;
|
|
|
|
/* if dst has more stack frames then src frame, free them */
|
|
for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
|
|
free_func_state(dst_state->frame[i]);
|
|
dst_state->frame[i] = NULL;
|
|
}
|
|
dst_state->speculative = src->speculative;
|
|
dst_state->curframe = src->curframe;
|
|
dst_state->parent = src->parent;
|
|
for (i = 0; i <= src->curframe; i++) {
|
|
dst = dst_state->frame[i];
|
|
if (!dst) {
|
|
dst = kzalloc(sizeof(*dst), GFP_KERNEL);
|
|
if (!dst)
|
|
return -ENOMEM;
|
|
dst_state->frame[i] = dst;
|
|
}
|
|
err = copy_func_state(dst, src->frame[i]);
|
|
if (err)
|
|
return err;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
|
|
int *insn_idx)
|
|
{
|
|
struct bpf_verifier_state *cur = env->cur_state;
|
|
struct bpf_verifier_stack_elem *elem, *head = env->head;
|
|
int err;
|
|
|
|
if (env->head == NULL)
|
|
return -ENOENT;
|
|
|
|
if (cur) {
|
|
err = copy_verifier_state(cur, &head->st);
|
|
if (err)
|
|
return err;
|
|
}
|
|
if (insn_idx)
|
|
*insn_idx = head->insn_idx;
|
|
if (prev_insn_idx)
|
|
*prev_insn_idx = head->prev_insn_idx;
|
|
elem = head->next;
|
|
free_verifier_state(&head->st, false);
|
|
kfree(head);
|
|
env->head = elem;
|
|
env->stack_size--;
|
|
return 0;
|
|
}
|
|
|
|
static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
|
|
int insn_idx, int prev_insn_idx,
|
|
bool speculative)
|
|
{
|
|
struct bpf_verifier_state *cur = env->cur_state;
|
|
struct bpf_verifier_stack_elem *elem;
|
|
int err;
|
|
|
|
elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
|
|
if (!elem)
|
|
goto err;
|
|
|
|
elem->insn_idx = insn_idx;
|
|
elem->prev_insn_idx = prev_insn_idx;
|
|
elem->next = env->head;
|
|
env->head = elem;
|
|
env->stack_size++;
|
|
err = copy_verifier_state(&elem->st, cur);
|
|
if (err)
|
|
goto err;
|
|
elem->st.speculative |= speculative;
|
|
if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
|
|
verbose(env, "BPF program is too complex\n");
|
|
goto err;
|
|
}
|
|
return &elem->st;
|
|
err:
|
|
free_verifier_state(env->cur_state, true);
|
|
env->cur_state = NULL;
|
|
/* pop all elements and return */
|
|
while (!pop_stack(env, NULL, NULL));
|
|
return NULL;
|
|
}
|
|
|
|
#define CALLER_SAVED_REGS 6
|
|
static const int caller_saved[CALLER_SAVED_REGS] = {
|
|
BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
|
|
};
|
|
|
|
static void __mark_reg_not_init(struct bpf_reg_state *reg);
|
|
|
|
/* Mark the unknown part of a register (variable offset or scalar value) as
|
|
* known to have the value @imm.
|
|
*/
|
|
static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
|
|
{
|
|
/* Clear id, off, and union(map_ptr, range) */
|
|
memset(((u8 *)reg) + sizeof(reg->type), 0,
|
|
offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
|
|
reg->var_off = tnum_const(imm);
|
|
reg->smin_value = (s64)imm;
|
|
reg->smax_value = (s64)imm;
|
|
reg->umin_value = imm;
|
|
reg->umax_value = imm;
|
|
}
|
|
|
|
/* Mark the 'variable offset' part of a register as zero. This should be
|
|
* used only on registers holding a pointer type.
|
|
*/
|
|
static void __mark_reg_known_zero(struct bpf_reg_state *reg)
|
|
{
|
|
__mark_reg_known(reg, 0);
|
|
}
|
|
|
|
static void __mark_reg_const_zero(struct bpf_reg_state *reg)
|
|
{
|
|
__mark_reg_known(reg, 0);
|
|
reg->type = SCALAR_VALUE;
|
|
}
|
|
|
|
static void mark_reg_known_zero(struct bpf_verifier_env *env,
|
|
struct bpf_reg_state *regs, u32 regno)
|
|
{
|
|
if (WARN_ON(regno >= MAX_BPF_REG)) {
|
|
verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
|
|
/* Something bad happened, let's kill all regs */
|
|
for (regno = 0; regno < MAX_BPF_REG; regno++)
|
|
__mark_reg_not_init(regs + regno);
|
|
return;
|
|
}
|
|
__mark_reg_known_zero(regs + regno);
|
|
}
|
|
|
|
static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
|
|
{
|
|
return type_is_pkt_pointer(reg->type);
|
|
}
|
|
|
|
static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
|
|
{
|
|
return reg_is_pkt_pointer(reg) ||
|
|
reg->type == PTR_TO_PACKET_END;
|
|
}
|
|
|
|
/* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
|
|
static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
|
|
enum bpf_reg_type which)
|
|
{
|
|
/* The register can already have a range from prior markings.
|
|
* This is fine as long as it hasn't been advanced from its
|
|
* origin.
|
|
*/
|
|
return reg->type == which &&
|
|
reg->id == 0 &&
|
|
reg->off == 0 &&
|
|
tnum_equals_const(reg->var_off, 0);
|
|
}
|
|
|
|
/* Attempts to improve min/max values based on var_off information */
|
|
static void __update_reg_bounds(struct bpf_reg_state *reg)
|
|
{
|
|
/* min signed is max(sign bit) | min(other bits) */
|
|
reg->smin_value = max_t(s64, reg->smin_value,
|
|
reg->var_off.value | (reg->var_off.mask & S64_MIN));
|
|
/* max signed is min(sign bit) | max(other bits) */
|
|
reg->smax_value = min_t(s64, reg->smax_value,
|
|
reg->var_off.value | (reg->var_off.mask & S64_MAX));
|
|
reg->umin_value = max(reg->umin_value, reg->var_off.value);
|
|
reg->umax_value = min(reg->umax_value,
|
|
reg->var_off.value | reg->var_off.mask);
|
|
}
|
|
|
|
/* Uses signed min/max values to inform unsigned, and vice-versa */
|
|
static void __reg_deduce_bounds(struct bpf_reg_state *reg)
|
|
{
|
|
/* Learn sign from signed bounds.
|
|
* If we cannot cross the sign boundary, then signed and unsigned bounds
|
|
* are the same, so combine. This works even in the negative case, e.g.
|
|
* -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
|
|
*/
|
|
if (reg->smin_value >= 0 || reg->smax_value < 0) {
|
|
reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
|
|
reg->umin_value);
|
|
reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
|
|
reg->umax_value);
|
|
return;
|
|
}
|
|
/* Learn sign from unsigned bounds. Signed bounds cross the sign
|
|
* boundary, so we must be careful.
|
|
*/
|
|
if ((s64)reg->umax_value >= 0) {
|
|
/* Positive. We can't learn anything from the smin, but smax
|
|
* is positive, hence safe.
|
|
*/
|
|
reg->smin_value = reg->umin_value;
|
|
reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
|
|
reg->umax_value);
|
|
} else if ((s64)reg->umin_value < 0) {
|
|
/* Negative. We can't learn anything from the smax, but smin
|
|
* is negative, hence safe.
|
|
*/
|
|
reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
|
|
reg->umin_value);
|
|
reg->smax_value = reg->umax_value;
|
|
}
|
|
}
|
|
|
|
/* Attempts to improve var_off based on unsigned min/max information */
|
|
static void __reg_bound_offset(struct bpf_reg_state *reg)
|
|
{
|
|
reg->var_off = tnum_intersect(reg->var_off,
|
|
tnum_range(reg->umin_value,
|
|
reg->umax_value));
|
|
}
|
|
|
|
/* Reset the min/max bounds of a register */
|
|
static void __mark_reg_unbounded(struct bpf_reg_state *reg)
|
|
{
|
|
reg->smin_value = S64_MIN;
|
|
reg->smax_value = S64_MAX;
|
|
reg->umin_value = 0;
|
|
reg->umax_value = U64_MAX;
|
|
}
|
|
|
|
/* Mark a register as having a completely unknown (scalar) value. */
|
|
static void __mark_reg_unknown(struct bpf_reg_state *reg)
|
|
{
|
|
/*
|
|
* Clear type, id, off, and union(map_ptr, range) and
|
|
* padding between 'type' and union
|
|
*/
|
|
memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
|
|
reg->type = SCALAR_VALUE;
|
|
reg->var_off = tnum_unknown;
|
|
reg->frameno = 0;
|
|
__mark_reg_unbounded(reg);
|
|
}
|
|
|
|
static void mark_reg_unknown(struct bpf_verifier_env *env,
|
|
struct bpf_reg_state *regs, u32 regno)
|
|
{
|
|
if (WARN_ON(regno >= MAX_BPF_REG)) {
|
|
verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
|
|
/* Something bad happened, let's kill all regs except FP */
|
|
for (regno = 0; regno < BPF_REG_FP; regno++)
|
|
__mark_reg_not_init(regs + regno);
|
|
return;
|
|
}
|
|
__mark_reg_unknown(regs + regno);
|
|
}
|
|
|
|
static void __mark_reg_not_init(struct bpf_reg_state *reg)
|
|
{
|
|
__mark_reg_unknown(reg);
|
|
reg->type = NOT_INIT;
|
|
}
|
|
|
|
static void mark_reg_not_init(struct bpf_verifier_env *env,
|
|
struct bpf_reg_state *regs, u32 regno)
|
|
{
|
|
if (WARN_ON(regno >= MAX_BPF_REG)) {
|
|
verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
|
|
/* Something bad happened, let's kill all regs except FP */
|
|
for (regno = 0; regno < BPF_REG_FP; regno++)
|
|
__mark_reg_not_init(regs + regno);
|
|
return;
|
|
}
|
|
__mark_reg_not_init(regs + regno);
|
|
}
|
|
|
|
static void init_reg_state(struct bpf_verifier_env *env,
|
|
struct bpf_func_state *state)
|
|
{
|
|
struct bpf_reg_state *regs = state->regs;
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++) {
|
|
mark_reg_not_init(env, regs, i);
|
|
regs[i].live = REG_LIVE_NONE;
|
|
}
|
|
|
|
/* frame pointer */
|
|
regs[BPF_REG_FP].type = PTR_TO_STACK;
|
|
mark_reg_known_zero(env, regs, BPF_REG_FP);
|
|
regs[BPF_REG_FP].frameno = state->frameno;
|
|
|
|
/* 1st arg to a function */
|
|
regs[BPF_REG_1].type = PTR_TO_CTX;
|
|
mark_reg_known_zero(env, regs, BPF_REG_1);
|
|
}
|
|
|
|
#define BPF_MAIN_FUNC (-1)
|
|
static void init_func_state(struct bpf_verifier_env *env,
|
|
struct bpf_func_state *state,
|
|
int callsite, int frameno, int subprogno)
|
|
{
|
|
state->callsite = callsite;
|
|
state->frameno = frameno;
|
|
state->subprogno = subprogno;
|
|
init_reg_state(env, state);
|
|
}
|
|
|
|
enum reg_arg_type {
|
|
SRC_OP, /* register is used as source operand */
|
|
DST_OP, /* register is used as destination operand */
|
|
DST_OP_NO_MARK /* same as above, check only, don't mark */
|
|
};
|
|
|
|
static int cmp_subprogs(const void *a, const void *b)
|
|
{
|
|
return ((struct bpf_subprog_info *)a)->start -
|
|
((struct bpf_subprog_info *)b)->start;
|
|
}
|
|
|
|
static int find_subprog(struct bpf_verifier_env *env, int off)
|
|
{
|
|
struct bpf_subprog_info *p;
|
|
|
|
p = bsearch(&off, env->subprog_info, env->subprog_cnt,
|
|
sizeof(env->subprog_info[0]), cmp_subprogs);
|
|
if (!p)
|
|
return -ENOENT;
|
|
return p - env->subprog_info;
|
|
|
|
}
|
|
|
|
static int add_subprog(struct bpf_verifier_env *env, int off)
|
|
{
|
|
int insn_cnt = env->prog->len;
|
|
int ret;
|
|
|
|
if (off >= insn_cnt || off < 0) {
|
|
verbose(env, "call to invalid destination\n");
|
|
return -EINVAL;
|
|
}
|
|
ret = find_subprog(env, off);
|
|
if (ret >= 0)
|
|
return 0;
|
|
if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
|
|
verbose(env, "too many subprograms\n");
|
|
return -E2BIG;
|
|
}
|
|
env->subprog_info[env->subprog_cnt++].start = off;
|
|
sort(env->subprog_info, env->subprog_cnt,
|
|
sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
|
|
return 0;
|
|
}
|
|
|
|
static int check_subprogs(struct bpf_verifier_env *env)
|
|
{
|
|
int i, ret, subprog_start, subprog_end, off, cur_subprog = 0;
|
|
struct bpf_subprog_info *subprog = env->subprog_info;
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
|
|
/* Add entry function. */
|
|
ret = add_subprog(env, 0);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
/* determine subprog starts. The end is one before the next starts */
|
|
for (i = 0; i < insn_cnt; i++) {
|
|
if (insn[i].code != (BPF_JMP | BPF_CALL))
|
|
continue;
|
|
if (insn[i].src_reg != BPF_PSEUDO_CALL)
|
|
continue;
|
|
if (!env->allow_ptr_leaks) {
|
|
verbose(env, "function calls to other bpf functions are allowed for root only\n");
|
|
return -EPERM;
|
|
}
|
|
if (bpf_prog_is_dev_bound(env->prog->aux)) {
|
|
verbose(env, "function calls in offloaded programs are not supported yet\n");
|
|
return -EINVAL;
|
|
}
|
|
ret = add_subprog(env, i + insn[i].imm + 1);
|
|
if (ret < 0)
|
|
return ret;
|
|
}
|
|
|
|
/* Add a fake 'exit' subprog which could simplify subprog iteration
|
|
* logic. 'subprog_cnt' should not be increased.
|
|
*/
|
|
subprog[env->subprog_cnt].start = insn_cnt;
|
|
|
|
if (env->log.level > 1)
|
|
for (i = 0; i < env->subprog_cnt; i++)
|
|
verbose(env, "func#%d @%d\n", i, subprog[i].start);
|
|
|
|
/* now check that all jumps are within the same subprog */
|
|
subprog_start = subprog[cur_subprog].start;
|
|
subprog_end = subprog[cur_subprog + 1].start;
|
|
for (i = 0; i < insn_cnt; i++) {
|
|
u8 code = insn[i].code;
|
|
|
|
if (BPF_CLASS(code) != BPF_JMP)
|
|
goto next;
|
|
if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
|
|
goto next;
|
|
off = i + insn[i].off + 1;
|
|
if (off < subprog_start || off >= subprog_end) {
|
|
verbose(env, "jump out of range from insn %d to %d\n", i, off);
|
|
return -EINVAL;
|
|
}
|
|
next:
|
|
if (i == subprog_end - 1) {
|
|
/* to avoid fall-through from one subprog into another
|
|
* the last insn of the subprog should be either exit
|
|
* or unconditional jump back
|
|
*/
|
|
if (code != (BPF_JMP | BPF_EXIT) &&
|
|
code != (BPF_JMP | BPF_JA)) {
|
|
verbose(env, "last insn is not an exit or jmp\n");
|
|
return -EINVAL;
|
|
}
|
|
subprog_start = subprog_end;
|
|
cur_subprog++;
|
|
if (cur_subprog < env->subprog_cnt)
|
|
subprog_end = subprog[cur_subprog + 1].start;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static
|
|
struct bpf_verifier_state *skip_callee(struct bpf_verifier_env *env,
|
|
const struct bpf_verifier_state *state,
|
|
struct bpf_verifier_state *parent,
|
|
u32 regno)
|
|
{
|
|
struct bpf_verifier_state *tmp = NULL;
|
|
|
|
/* 'parent' could be a state of caller and
|
|
* 'state' could be a state of callee. In such case
|
|
* parent->curframe < state->curframe
|
|
* and it's ok for r1 - r5 registers
|
|
*
|
|
* 'parent' could be a callee's state after it bpf_exit-ed.
|
|
* In such case parent->curframe > state->curframe
|
|
* and it's ok for r0 only
|
|
*/
|
|
if (parent->curframe == state->curframe ||
|
|
(parent->curframe < state->curframe &&
|
|
regno >= BPF_REG_1 && regno <= BPF_REG_5) ||
|
|
(parent->curframe > state->curframe &&
|
|
regno == BPF_REG_0))
|
|
return parent;
|
|
|
|
if (parent->curframe > state->curframe &&
|
|
regno >= BPF_REG_6) {
|
|
/* for callee saved regs we have to skip the whole chain
|
|
* of states that belong to callee and mark as LIVE_READ
|
|
* the registers before the call
|
|
*/
|
|
tmp = parent;
|
|
while (tmp && tmp->curframe != state->curframe) {
|
|
tmp = tmp->parent;
|
|
}
|
|
if (!tmp)
|
|
goto bug;
|
|
parent = tmp;
|
|
} else {
|
|
goto bug;
|
|
}
|
|
return parent;
|
|
bug:
|
|
verbose(env, "verifier bug regno %d tmp %p\n", regno, tmp);
|
|
verbose(env, "regno %d parent frame %d current frame %d\n",
|
|
regno, parent->curframe, state->curframe);
|
|
return NULL;
|
|
}
|
|
|
|
static int mark_reg_read(struct bpf_verifier_env *env,
|
|
const struct bpf_verifier_state *state,
|
|
struct bpf_verifier_state *parent,
|
|
u32 regno)
|
|
{
|
|
bool writes = parent == state->parent; /* Observe write marks */
|
|
|
|
if (regno == BPF_REG_FP)
|
|
/* We don't need to worry about FP liveness because it's read-only */
|
|
return 0;
|
|
|
|
while (parent) {
|
|
/* if read wasn't screened by an earlier write ... */
|
|
if (writes && state->frame[state->curframe]->regs[regno].live & REG_LIVE_WRITTEN)
|
|
break;
|
|
parent = skip_callee(env, state, parent, regno);
|
|
if (!parent)
|
|
return -EFAULT;
|
|
/* ... then we depend on parent's value */
|
|
parent->frame[parent->curframe]->regs[regno].live |= REG_LIVE_READ;
|
|
state = parent;
|
|
parent = state->parent;
|
|
writes = true;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
|
|
enum reg_arg_type t)
|
|
{
|
|
struct bpf_verifier_state *vstate = env->cur_state;
|
|
struct bpf_func_state *state = vstate->frame[vstate->curframe];
|
|
struct bpf_reg_state *regs = state->regs;
|
|
|
|
if (regno >= MAX_BPF_REG) {
|
|
verbose(env, "R%d is invalid\n", regno);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (t == SRC_OP) {
|
|
/* check whether register used as source operand can be read */
|
|
if (regs[regno].type == NOT_INIT) {
|
|
verbose(env, "R%d !read_ok\n", regno);
|
|
return -EACCES;
|
|
}
|
|
return mark_reg_read(env, vstate, vstate->parent, regno);
|
|
} else {
|
|
/* check whether register used as dest operand can be written to */
|
|
if (regno == BPF_REG_FP) {
|
|
verbose(env, "frame pointer is read only\n");
|
|
return -EACCES;
|
|
}
|
|
regs[regno].live |= REG_LIVE_WRITTEN;
|
|
if (t == DST_OP)
|
|
mark_reg_unknown(env, regs, regno);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static bool is_spillable_regtype(enum bpf_reg_type type)
|
|
{
|
|
switch (type) {
|
|
case PTR_TO_MAP_VALUE:
|
|
case PTR_TO_MAP_VALUE_OR_NULL:
|
|
case PTR_TO_STACK:
|
|
case PTR_TO_CTX:
|
|
case PTR_TO_PACKET:
|
|
case PTR_TO_PACKET_META:
|
|
case PTR_TO_PACKET_END:
|
|
case CONST_PTR_TO_MAP:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* Does this register contain a constant zero? */
|
|
static bool register_is_null(struct bpf_reg_state *reg)
|
|
{
|
|
return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
|
|
}
|
|
|
|
/* check_stack_read/write functions track spill/fill of registers,
|
|
* stack boundary and alignment are checked in check_mem_access()
|
|
*/
|
|
static int check_stack_write(struct bpf_verifier_env *env,
|
|
struct bpf_func_state *state, /* func where register points to */
|
|
int off, int size, int value_regno, int insn_idx)
|
|
{
|
|
struct bpf_func_state *cur; /* state of the current function */
|
|
int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
|
|
enum bpf_reg_type type;
|
|
|
|
err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE),
|
|
true);
|
|
if (err)
|
|
return err;
|
|
/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
|
|
* so it's aligned access and [off, off + size) are within stack limits
|
|
*/
|
|
if (!env->allow_ptr_leaks &&
|
|
state->stack[spi].slot_type[0] == STACK_SPILL &&
|
|
size != BPF_REG_SIZE) {
|
|
verbose(env, "attempt to corrupt spilled pointer on stack\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
cur = env->cur_state->frame[env->cur_state->curframe];
|
|
if (value_regno >= 0 &&
|
|
is_spillable_regtype((type = cur->regs[value_regno].type))) {
|
|
|
|
/* register containing pointer is being spilled into stack */
|
|
if (size != BPF_REG_SIZE) {
|
|
verbose(env, "invalid size of register spill\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
if (state != cur && type == PTR_TO_STACK) {
|
|
verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* save register state */
|
|
state->stack[spi].spilled_ptr = cur->regs[value_regno];
|
|
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
|
|
|
|
for (i = 0; i < BPF_REG_SIZE; i++) {
|
|
if (state->stack[spi].slot_type[i] == STACK_MISC &&
|
|
!env->allow_ptr_leaks) {
|
|
int *poff = &env->insn_aux_data[insn_idx].sanitize_stack_off;
|
|
int soff = (-spi - 1) * BPF_REG_SIZE;
|
|
|
|
/* detected reuse of integer stack slot with a pointer
|
|
* which means either llvm is reusing stack slot or
|
|
* an attacker is trying to exploit CVE-2018-3639
|
|
* (speculative store bypass)
|
|
* Have to sanitize that slot with preemptive
|
|
* store of zero.
|
|
*/
|
|
if (*poff && *poff != soff) {
|
|
/* disallow programs where single insn stores
|
|
* into two different stack slots, since verifier
|
|
* cannot sanitize them
|
|
*/
|
|
verbose(env,
|
|
"insn %d cannot access two stack slots fp%d and fp%d",
|
|
insn_idx, *poff, soff);
|
|
return -EINVAL;
|
|
}
|
|
*poff = soff;
|
|
}
|
|
state->stack[spi].slot_type[i] = STACK_SPILL;
|
|
}
|
|
} else {
|
|
u8 type = STACK_MISC;
|
|
|
|
/* regular write of data into stack */
|
|
state->stack[spi].spilled_ptr = (struct bpf_reg_state) {};
|
|
|
|
/* only mark the slot as written if all 8 bytes were written
|
|
* otherwise read propagation may incorrectly stop too soon
|
|
* when stack slots are partially written.
|
|
* This heuristic means that read propagation will be
|
|
* conservative, since it will add reg_live_read marks
|
|
* to stack slots all the way to first state when programs
|
|
* writes+reads less than 8 bytes
|
|
*/
|
|
if (size == BPF_REG_SIZE)
|
|
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
|
|
|
|
/* when we zero initialize stack slots mark them as such */
|
|
if (value_regno >= 0 &&
|
|
register_is_null(&cur->regs[value_regno]))
|
|
type = STACK_ZERO;
|
|
|
|
for (i = 0; i < size; i++)
|
|
state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] =
|
|
type;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* registers of every function are unique and mark_reg_read() propagates
|
|
* the liveness in the following cases:
|
|
* - from callee into caller for R1 - R5 that were used as arguments
|
|
* - from caller into callee for R0 that used as result of the call
|
|
* - from caller to the same caller skipping states of the callee for R6 - R9,
|
|
* since R6 - R9 are callee saved by implicit function prologue and
|
|
* caller's R6 != callee's R6, so when we propagate liveness up to
|
|
* parent states we need to skip callee states for R6 - R9.
|
|
*
|
|
* stack slot marking is different, since stacks of caller and callee are
|
|
* accessible in both (since caller can pass a pointer to caller's stack to
|
|
* callee which can pass it to another function), hence mark_stack_slot_read()
|
|
* has to propagate the stack liveness to all parent states at given frame number.
|
|
* Consider code:
|
|
* f1() {
|
|
* ptr = fp - 8;
|
|
* *ptr = ctx;
|
|
* call f2 {
|
|
* .. = *ptr;
|
|
* }
|
|
* .. = *ptr;
|
|
* }
|
|
* First *ptr is reading from f1's stack and mark_stack_slot_read() has
|
|
* to mark liveness at the f1's frame and not f2's frame.
|
|
* Second *ptr is also reading from f1's stack and mark_stack_slot_read() has
|
|
* to propagate liveness to f2 states at f1's frame level and further into
|
|
* f1 states at f1's frame level until write into that stack slot
|
|
*/
|
|
static void mark_stack_slot_read(struct bpf_verifier_env *env,
|
|
const struct bpf_verifier_state *state,
|
|
struct bpf_verifier_state *parent,
|
|
int slot, int frameno)
|
|
{
|
|
bool writes = parent == state->parent; /* Observe write marks */
|
|
|
|
while (parent) {
|
|
if (parent->frame[frameno]->allocated_stack <= slot * BPF_REG_SIZE)
|
|
/* since LIVE_WRITTEN mark is only done for full 8-byte
|
|
* write the read marks are conservative and parent
|
|
* state may not even have the stack allocated. In such case
|
|
* end the propagation, since the loop reached beginning
|
|
* of the function
|
|
*/
|
|
break;
|
|
/* if read wasn't screened by an earlier write ... */
|
|
if (writes && state->frame[frameno]->stack[slot].spilled_ptr.live & REG_LIVE_WRITTEN)
|
|
break;
|
|
/* ... then we depend on parent's value */
|
|
parent->frame[frameno]->stack[slot].spilled_ptr.live |= REG_LIVE_READ;
|
|
state = parent;
|
|
parent = state->parent;
|
|
writes = true;
|
|
}
|
|
}
|
|
|
|
static int check_stack_read(struct bpf_verifier_env *env,
|
|
struct bpf_func_state *reg_state /* func where register points to */,
|
|
int off, int size, int value_regno)
|
|
{
|
|
struct bpf_verifier_state *vstate = env->cur_state;
|
|
struct bpf_func_state *state = vstate->frame[vstate->curframe];
|
|
int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
|
|
u8 *stype;
|
|
|
|
if (reg_state->allocated_stack <= slot) {
|
|
verbose(env, "invalid read from stack off %d+0 size %d\n",
|
|
off, size);
|
|
return -EACCES;
|
|
}
|
|
stype = reg_state->stack[spi].slot_type;
|
|
|
|
if (stype[0] == STACK_SPILL) {
|
|
if (size != BPF_REG_SIZE) {
|
|
verbose(env, "invalid size of register spill\n");
|
|
return -EACCES;
|
|
}
|
|
for (i = 1; i < BPF_REG_SIZE; i++) {
|
|
if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) {
|
|
verbose(env, "corrupted spill memory\n");
|
|
return -EACCES;
|
|
}
|
|
}
|
|
|
|
if (value_regno >= 0) {
|
|
/* restore register state from stack */
|
|
state->regs[value_regno] = reg_state->stack[spi].spilled_ptr;
|
|
/* mark reg as written since spilled pointer state likely
|
|
* has its liveness marks cleared by is_state_visited()
|
|
* which resets stack/reg liveness for state transitions
|
|
*/
|
|
state->regs[value_regno].live |= REG_LIVE_WRITTEN;
|
|
}
|
|
mark_stack_slot_read(env, vstate, vstate->parent, spi,
|
|
reg_state->frameno);
|
|
return 0;
|
|
} else {
|
|
int zeros = 0;
|
|
|
|
for (i = 0; i < size; i++) {
|
|
if (stype[(slot - i) % BPF_REG_SIZE] == STACK_MISC)
|
|
continue;
|
|
if (stype[(slot - i) % BPF_REG_SIZE] == STACK_ZERO) {
|
|
zeros++;
|
|
continue;
|
|
}
|
|
verbose(env, "invalid read from stack off %d+%d size %d\n",
|
|
off, i, size);
|
|
return -EACCES;
|
|
}
|
|
mark_stack_slot_read(env, vstate, vstate->parent, spi,
|
|
reg_state->frameno);
|
|
if (value_regno >= 0) {
|
|
if (zeros == size) {
|
|
/* any size read into register is zero extended,
|
|
* so the whole register == const_zero
|
|
*/
|
|
__mark_reg_const_zero(&state->regs[value_regno]);
|
|
} else {
|
|
/* have read misc data from the stack */
|
|
mark_reg_unknown(env, state->regs, value_regno);
|
|
}
|
|
state->regs[value_regno].live |= REG_LIVE_WRITTEN;
|
|
}
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
static int check_stack_access(struct bpf_verifier_env *env,
|
|
const struct bpf_reg_state *reg,
|
|
int off, int size)
|
|
{
|
|
/* Stack accesses must be at a fixed offset, so that we
|
|
* can determine what type of data were returned. See
|
|
* check_stack_read().
|
|
*/
|
|
if (!tnum_is_const(reg->var_off)) {
|
|
char tn_buf[48];
|
|
|
|
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
|
|
verbose(env, "variable stack access var_off=%s off=%d size=%d\n",
|
|
tn_buf, off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (off >= 0 || off < -MAX_BPF_STACK) {
|
|
verbose(env, "invalid stack off=%d size=%d\n", off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* check read/write into map element returned by bpf_map_lookup_elem() */
|
|
static int __check_map_access(struct bpf_verifier_env *env, u32 regno, int off,
|
|
int size, bool zero_size_allowed)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env);
|
|
struct bpf_map *map = regs[regno].map_ptr;
|
|
|
|
if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) ||
|
|
off + size > map->value_size) {
|
|
verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
|
|
map->value_size, off, size);
|
|
return -EACCES;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* check read/write into a map element with possible variable offset */
|
|
static int check_map_access(struct bpf_verifier_env *env, u32 regno,
|
|
int off, int size, bool zero_size_allowed)
|
|
{
|
|
struct bpf_verifier_state *vstate = env->cur_state;
|
|
struct bpf_func_state *state = vstate->frame[vstate->curframe];
|
|
struct bpf_reg_state *reg = &state->regs[regno];
|
|
int err;
|
|
|
|
/* We may have adjusted the register to this map value, so we
|
|
* need to try adding each of min_value and max_value to off
|
|
* to make sure our theoretical access will be safe.
|
|
*/
|
|
if (env->log.level)
|
|
print_verifier_state(env, state);
|
|
|
|
/* The minimum value is only important with signed
|
|
* comparisons where we can't assume the floor of a
|
|
* value is 0. If we are using signed variables for our
|
|
* index'es we need to make sure that whatever we use
|
|
* will have a set floor within our range.
|
|
*/
|
|
if (reg->smin_value < 0 &&
|
|
(reg->smin_value == S64_MIN ||
|
|
(off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) ||
|
|
reg->smin_value + off < 0)) {
|
|
verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
err = __check_map_access(env, regno, reg->smin_value + off, size,
|
|
zero_size_allowed);
|
|
if (err) {
|
|
verbose(env, "R%d min value is outside of the array range\n",
|
|
regno);
|
|
return err;
|
|
}
|
|
|
|
/* If we haven't set a max value then we need to bail since we can't be
|
|
* sure we won't do bad things.
|
|
* If reg->umax_value + off could overflow, treat that as unbounded too.
|
|
*/
|
|
if (reg->umax_value >= BPF_MAX_VAR_OFF) {
|
|
verbose(env, "R%d unbounded memory access, make sure to bounds check any array access into a map\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
err = __check_map_access(env, regno, reg->umax_value + off, size,
|
|
zero_size_allowed);
|
|
if (err)
|
|
verbose(env, "R%d max value is outside of the array range\n",
|
|
regno);
|
|
return err;
|
|
}
|
|
|
|
#define MAX_PACKET_OFF 0xffff
|
|
|
|
static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
|
|
const struct bpf_call_arg_meta *meta,
|
|
enum bpf_access_type t)
|
|
{
|
|
switch (env->prog->type) {
|
|
case BPF_PROG_TYPE_LWT_IN:
|
|
case BPF_PROG_TYPE_LWT_OUT:
|
|
case BPF_PROG_TYPE_LWT_SEG6LOCAL:
|
|
case BPF_PROG_TYPE_SK_REUSEPORT:
|
|
/* dst_input() and dst_output() can't write for now */
|
|
if (t == BPF_WRITE)
|
|
return false;
|
|
/* fallthrough */
|
|
case BPF_PROG_TYPE_SCHED_CLS:
|
|
case BPF_PROG_TYPE_SCHED_ACT:
|
|
case BPF_PROG_TYPE_XDP:
|
|
case BPF_PROG_TYPE_LWT_XMIT:
|
|
case BPF_PROG_TYPE_SK_SKB:
|
|
case BPF_PROG_TYPE_SK_MSG:
|
|
if (meta)
|
|
return meta->pkt_access;
|
|
|
|
env->seen_direct_write = true;
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
static int __check_packet_access(struct bpf_verifier_env *env, u32 regno,
|
|
int off, int size, bool zero_size_allowed)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env);
|
|
struct bpf_reg_state *reg = ®s[regno];
|
|
|
|
if (off < 0 || size < 0 || (size == 0 && !zero_size_allowed) ||
|
|
(u64)off + size > reg->range) {
|
|
verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
|
|
off, size, regno, reg->id, reg->off, reg->range);
|
|
return -EACCES;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
|
|
int size, bool zero_size_allowed)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env);
|
|
struct bpf_reg_state *reg = ®s[regno];
|
|
int err;
|
|
|
|
/* We may have added a variable offset to the packet pointer; but any
|
|
* reg->range we have comes after that. We are only checking the fixed
|
|
* offset.
|
|
*/
|
|
|
|
/* We don't allow negative numbers, because we aren't tracking enough
|
|
* detail to prove they're safe.
|
|
*/
|
|
if (reg->smin_value < 0) {
|
|
verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
err = __check_packet_access(env, regno, off, size, zero_size_allowed);
|
|
if (err) {
|
|
verbose(env, "R%d offset is outside of the packet\n", regno);
|
|
return err;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
/* check access to 'struct bpf_context' fields. Supports fixed offsets only */
|
|
static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
|
|
enum bpf_access_type t, enum bpf_reg_type *reg_type)
|
|
{
|
|
struct bpf_insn_access_aux info = {
|
|
.reg_type = *reg_type,
|
|
};
|
|
|
|
if (env->ops->is_valid_access &&
|
|
env->ops->is_valid_access(off, size, t, env->prog, &info)) {
|
|
/* A non zero info.ctx_field_size indicates that this field is a
|
|
* candidate for later verifier transformation to load the whole
|
|
* field and then apply a mask when accessed with a narrower
|
|
* access than actual ctx access size. A zero info.ctx_field_size
|
|
* will only allow for whole field access and rejects any other
|
|
* type of narrower access.
|
|
*/
|
|
*reg_type = info.reg_type;
|
|
|
|
env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
|
|
/* remember the offset of last byte accessed in ctx */
|
|
if (env->prog->aux->max_ctx_offset < off + size)
|
|
env->prog->aux->max_ctx_offset = off + size;
|
|
return 0;
|
|
}
|
|
|
|
verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
static bool __is_pointer_value(bool allow_ptr_leaks,
|
|
const struct bpf_reg_state *reg)
|
|
{
|
|
if (allow_ptr_leaks)
|
|
return false;
|
|
|
|
return reg->type != SCALAR_VALUE;
|
|
}
|
|
|
|
static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
|
|
{
|
|
return __is_pointer_value(env->allow_ptr_leaks, cur_regs(env) + regno);
|
|
}
|
|
|
|
static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
|
|
{
|
|
const struct bpf_reg_state *reg = cur_regs(env) + regno;
|
|
|
|
return reg->type == PTR_TO_CTX;
|
|
}
|
|
|
|
static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
|
|
{
|
|
const struct bpf_reg_state *reg = cur_regs(env) + regno;
|
|
|
|
return type_is_pkt_pointer(reg->type);
|
|
}
|
|
|
|
static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
|
|
const struct bpf_reg_state *reg,
|
|
int off, int size, bool strict)
|
|
{
|
|
struct tnum reg_off;
|
|
int ip_align;
|
|
|
|
/* Byte size accesses are always allowed. */
|
|
if (!strict || size == 1)
|
|
return 0;
|
|
|
|
/* For platforms that do not have a Kconfig enabling
|
|
* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
|
|
* NET_IP_ALIGN is universally set to '2'. And on platforms
|
|
* that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
|
|
* to this code only in strict mode where we want to emulate
|
|
* the NET_IP_ALIGN==2 checking. Therefore use an
|
|
* unconditional IP align value of '2'.
|
|
*/
|
|
ip_align = 2;
|
|
|
|
reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
|
|
if (!tnum_is_aligned(reg_off, size)) {
|
|
char tn_buf[48];
|
|
|
|
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
|
|
verbose(env,
|
|
"misaligned packet access off %d+%s+%d+%d size %d\n",
|
|
ip_align, tn_buf, reg->off, off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
|
|
const struct bpf_reg_state *reg,
|
|
const char *pointer_desc,
|
|
int off, int size, bool strict)
|
|
{
|
|
struct tnum reg_off;
|
|
|
|
/* Byte size accesses are always allowed. */
|
|
if (!strict || size == 1)
|
|
return 0;
|
|
|
|
reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
|
|
if (!tnum_is_aligned(reg_off, size)) {
|
|
char tn_buf[48];
|
|
|
|
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
|
|
verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
|
|
pointer_desc, tn_buf, reg->off, off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int check_ptr_alignment(struct bpf_verifier_env *env,
|
|
const struct bpf_reg_state *reg, int off,
|
|
int size, bool strict_alignment_once)
|
|
{
|
|
bool strict = env->strict_alignment || strict_alignment_once;
|
|
const char *pointer_desc = "";
|
|
|
|
switch (reg->type) {
|
|
case PTR_TO_PACKET:
|
|
case PTR_TO_PACKET_META:
|
|
/* Special case, because of NET_IP_ALIGN. Given metadata sits
|
|
* right in front, treat it the very same way.
|
|
*/
|
|
return check_pkt_ptr_alignment(env, reg, off, size, strict);
|
|
case PTR_TO_MAP_VALUE:
|
|
pointer_desc = "value ";
|
|
break;
|
|
case PTR_TO_CTX:
|
|
pointer_desc = "context ";
|
|
break;
|
|
case PTR_TO_STACK:
|
|
pointer_desc = "stack ";
|
|
/* The stack spill tracking logic in check_stack_write()
|
|
* and check_stack_read() relies on stack accesses being
|
|
* aligned.
|
|
*/
|
|
strict = true;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
|
|
strict);
|
|
}
|
|
|
|
static int update_stack_depth(struct bpf_verifier_env *env,
|
|
const struct bpf_func_state *func,
|
|
int off)
|
|
{
|
|
u16 stack = env->subprog_info[func->subprogno].stack_depth;
|
|
|
|
if (stack >= -off)
|
|
return 0;
|
|
|
|
/* update known max for given subprogram */
|
|
env->subprog_info[func->subprogno].stack_depth = -off;
|
|
return 0;
|
|
}
|
|
|
|
/* starting from main bpf function walk all instructions of the function
|
|
* and recursively walk all callees that given function can call.
|
|
* Ignore jump and exit insns.
|
|
* Since recursion is prevented by check_cfg() this algorithm
|
|
* only needs a local stack of MAX_CALL_FRAMES to remember callsites
|
|
*/
|
|
static int check_max_stack_depth(struct bpf_verifier_env *env)
|
|
{
|
|
int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
|
|
struct bpf_subprog_info *subprog = env->subprog_info;
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int ret_insn[MAX_CALL_FRAMES];
|
|
int ret_prog[MAX_CALL_FRAMES];
|
|
|
|
process_func:
|
|
/* round up to 32-bytes, since this is granularity
|
|
* of interpreter stack size
|
|
*/
|
|
depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
|
|
if (depth > MAX_BPF_STACK) {
|
|
verbose(env, "combined stack size of %d calls is %d. Too large\n",
|
|
frame + 1, depth);
|
|
return -EACCES;
|
|
}
|
|
continue_func:
|
|
subprog_end = subprog[idx + 1].start;
|
|
for (; i < subprog_end; i++) {
|
|
if (insn[i].code != (BPF_JMP | BPF_CALL))
|
|
continue;
|
|
if (insn[i].src_reg != BPF_PSEUDO_CALL)
|
|
continue;
|
|
/* remember insn and function to return to */
|
|
ret_insn[frame] = i + 1;
|
|
ret_prog[frame] = idx;
|
|
|
|
/* find the callee */
|
|
i = i + insn[i].imm + 1;
|
|
idx = find_subprog(env, i);
|
|
if (idx < 0) {
|
|
WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
|
|
i);
|
|
return -EFAULT;
|
|
}
|
|
frame++;
|
|
if (frame >= MAX_CALL_FRAMES) {
|
|
WARN_ONCE(1, "verifier bug. Call stack is too deep\n");
|
|
return -EFAULT;
|
|
}
|
|
goto process_func;
|
|
}
|
|
/* end of for() loop means the last insn of the 'subprog'
|
|
* was reached. Doesn't matter whether it was JA or EXIT
|
|
*/
|
|
if (frame == 0)
|
|
return 0;
|
|
depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
|
|
frame--;
|
|
i = ret_insn[frame];
|
|
idx = ret_prog[frame];
|
|
goto continue_func;
|
|
}
|
|
|
|
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
|
|
static int get_callee_stack_depth(struct bpf_verifier_env *env,
|
|
const struct bpf_insn *insn, int idx)
|
|
{
|
|
int start = idx + insn->imm + 1, subprog;
|
|
|
|
subprog = find_subprog(env, start);
|
|
if (subprog < 0) {
|
|
WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
|
|
start);
|
|
return -EFAULT;
|
|
}
|
|
return env->subprog_info[subprog].stack_depth;
|
|
}
|
|
#endif
|
|
|
|
static int check_ctx_reg(struct bpf_verifier_env *env,
|
|
const struct bpf_reg_state *reg, int regno)
|
|
{
|
|
/* Access to ctx or passing it to a helper is only allowed in
|
|
* its original, unmodified form.
|
|
*/
|
|
|
|
if (reg->off) {
|
|
verbose(env, "dereference of modified ctx ptr R%d off=%d disallowed\n",
|
|
regno, reg->off);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
|
|
char tn_buf[48];
|
|
|
|
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
|
|
verbose(env, "variable ctx access var_off=%s disallowed\n", tn_buf);
|
|
return -EACCES;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* truncate register to smaller size (in bytes)
|
|
* must be called with size < BPF_REG_SIZE
|
|
*/
|
|
static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
|
|
{
|
|
u64 mask;
|
|
|
|
/* clear high bits in bit representation */
|
|
reg->var_off = tnum_cast(reg->var_off, size);
|
|
|
|
/* fix arithmetic bounds */
|
|
mask = ((u64)1 << (size * 8)) - 1;
|
|
if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
|
|
reg->umin_value &= mask;
|
|
reg->umax_value &= mask;
|
|
} else {
|
|
reg->umin_value = 0;
|
|
reg->umax_value = mask;
|
|
}
|
|
reg->smin_value = reg->umin_value;
|
|
reg->smax_value = reg->umax_value;
|
|
}
|
|
|
|
/* check whether memory at (regno + off) is accessible for t = (read | write)
|
|
* if t==write, value_regno is a register which value is stored into memory
|
|
* if t==read, value_regno is a register which will receive the value from memory
|
|
* if t==write && value_regno==-1, some unknown value is stored into memory
|
|
* if t==read && value_regno==-1, don't care what we read from memory
|
|
*/
|
|
static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
|
|
int off, int bpf_size, enum bpf_access_type t,
|
|
int value_regno, bool strict_alignment_once)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env);
|
|
struct bpf_reg_state *reg = regs + regno;
|
|
struct bpf_func_state *state;
|
|
int size, err = 0;
|
|
|
|
size = bpf_size_to_bytes(bpf_size);
|
|
if (size < 0)
|
|
return size;
|
|
|
|
/* alignment checks will add in reg->off themselves */
|
|
err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
|
|
if (err)
|
|
return err;
|
|
|
|
/* for access checks, reg->off is just part of off */
|
|
off += reg->off;
|
|
|
|
if (reg->type == PTR_TO_MAP_VALUE) {
|
|
if (t == BPF_WRITE && value_regno >= 0 &&
|
|
is_pointer_value(env, value_regno)) {
|
|
verbose(env, "R%d leaks addr into map\n", value_regno);
|
|
return -EACCES;
|
|
}
|
|
|
|
err = check_map_access(env, regno, off, size, false);
|
|
if (!err && t == BPF_READ && value_regno >= 0)
|
|
mark_reg_unknown(env, regs, value_regno);
|
|
|
|
} else if (reg->type == PTR_TO_CTX) {
|
|
enum bpf_reg_type reg_type = SCALAR_VALUE;
|
|
|
|
if (t == BPF_WRITE && value_regno >= 0 &&
|
|
is_pointer_value(env, value_regno)) {
|
|
verbose(env, "R%d leaks addr into ctx\n", value_regno);
|
|
return -EACCES;
|
|
}
|
|
|
|
err = check_ctx_reg(env, reg, regno);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
err = check_ctx_access(env, insn_idx, off, size, t, ®_type);
|
|
if (!err && t == BPF_READ && value_regno >= 0) {
|
|
/* ctx access returns either a scalar, or a
|
|
* PTR_TO_PACKET[_META,_END]. In the latter
|
|
* case, we know the offset is zero.
|
|
*/
|
|
if (reg_type == SCALAR_VALUE)
|
|
mark_reg_unknown(env, regs, value_regno);
|
|
else
|
|
mark_reg_known_zero(env, regs,
|
|
value_regno);
|
|
regs[value_regno].type = reg_type;
|
|
}
|
|
|
|
} else if (reg->type == PTR_TO_STACK) {
|
|
off += reg->var_off.value;
|
|
err = check_stack_access(env, reg, off, size);
|
|
if (err)
|
|
return err;
|
|
|
|
state = func(env, reg);
|
|
err = update_stack_depth(env, state, off);
|
|
if (err)
|
|
return err;
|
|
|
|
if (t == BPF_WRITE)
|
|
err = check_stack_write(env, state, off, size,
|
|
value_regno, insn_idx);
|
|
else
|
|
err = check_stack_read(env, state, off, size,
|
|
value_regno);
|
|
} else if (reg_is_pkt_pointer(reg)) {
|
|
if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
|
|
verbose(env, "cannot write into packet\n");
|
|
return -EACCES;
|
|
}
|
|
if (t == BPF_WRITE && value_regno >= 0 &&
|
|
is_pointer_value(env, value_regno)) {
|
|
verbose(env, "R%d leaks addr into packet\n",
|
|
value_regno);
|
|
return -EACCES;
|
|
}
|
|
err = check_packet_access(env, regno, off, size, false);
|
|
if (!err && t == BPF_READ && value_regno >= 0)
|
|
mark_reg_unknown(env, regs, value_regno);
|
|
} else {
|
|
verbose(env, "R%d invalid mem access '%s'\n", regno,
|
|
reg_type_str[reg->type]);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
|
|
regs[value_regno].type == SCALAR_VALUE) {
|
|
/* b/h/w load zero-extends, mark upper bits as known 0 */
|
|
coerce_reg_to_size(®s[value_regno], size);
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
|
|
{
|
|
int err;
|
|
|
|
if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
|
|
insn->imm != 0) {
|
|
verbose(env, "BPF_XADD uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(env, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_pointer_value(env, insn->src_reg)) {
|
|
verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (is_ctx_reg(env, insn->dst_reg) ||
|
|
is_pkt_reg(env, insn->dst_reg)) {
|
|
verbose(env, "BPF_XADD stores into R%d %s is not allowed\n",
|
|
insn->dst_reg, is_ctx_reg(env, insn->dst_reg) ?
|
|
"context" : "packet");
|
|
return -EACCES;
|
|
}
|
|
|
|
/* check whether atomic_add can read the memory */
|
|
err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_READ, -1, true);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check whether atomic_add can write into the same memory */
|
|
return check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_WRITE, -1, true);
|
|
}
|
|
|
|
/* when register 'regno' is passed into function that will read 'access_size'
|
|
* bytes from that pointer, make sure that it's within stack boundary
|
|
* and all elements of stack are initialized.
|
|
* Unlike most pointer bounds-checking functions, this one doesn't take an
|
|
* 'off' argument, so it has to add in reg->off itself.
|
|
*/
|
|
static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
|
|
int access_size, bool zero_size_allowed,
|
|
struct bpf_call_arg_meta *meta)
|
|
{
|
|
struct bpf_reg_state *reg = cur_regs(env) + regno;
|
|
struct bpf_func_state *state = func(env, reg);
|
|
int off, i, slot, spi;
|
|
|
|
if (reg->type != PTR_TO_STACK) {
|
|
/* Allow zero-byte read from NULL, regardless of pointer type */
|
|
if (zero_size_allowed && access_size == 0 &&
|
|
register_is_null(reg))
|
|
return 0;
|
|
|
|
verbose(env, "R%d type=%s expected=%s\n", regno,
|
|
reg_type_str[reg->type],
|
|
reg_type_str[PTR_TO_STACK]);
|
|
return -EACCES;
|
|
}
|
|
|
|
/* Only allow fixed-offset stack reads */
|
|
if (!tnum_is_const(reg->var_off)) {
|
|
char tn_buf[48];
|
|
|
|
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
|
|
verbose(env, "invalid variable stack read R%d var_off=%s\n",
|
|
regno, tn_buf);
|
|
return -EACCES;
|
|
}
|
|
off = reg->off + reg->var_off.value;
|
|
if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
|
|
access_size < 0 || (access_size == 0 && !zero_size_allowed)) {
|
|
verbose(env, "invalid stack type R%d off=%d access_size=%d\n",
|
|
regno, off, access_size);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (meta && meta->raw_mode) {
|
|
meta->access_size = access_size;
|
|
meta->regno = regno;
|
|
return 0;
|
|
}
|
|
|
|
for (i = 0; i < access_size; i++) {
|
|
u8 *stype;
|
|
|
|
slot = -(off + i) - 1;
|
|
spi = slot / BPF_REG_SIZE;
|
|
if (state->allocated_stack <= slot)
|
|
goto err;
|
|
stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
|
|
if (*stype == STACK_MISC)
|
|
goto mark;
|
|
if (*stype == STACK_ZERO) {
|
|
/* helper can write anything into the stack */
|
|
*stype = STACK_MISC;
|
|
goto mark;
|
|
}
|
|
err:
|
|
verbose(env, "invalid indirect read from stack off %d+%d size %d\n",
|
|
off, i, access_size);
|
|
return -EACCES;
|
|
mark:
|
|
/* reading any byte out of 8-byte 'spill_slot' will cause
|
|
* the whole slot to be marked as 'read'
|
|
*/
|
|
mark_stack_slot_read(env, env->cur_state, env->cur_state->parent,
|
|
spi, state->frameno);
|
|
}
|
|
return update_stack_depth(env, state, off);
|
|
}
|
|
|
|
static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
|
|
int access_size, bool zero_size_allowed,
|
|
struct bpf_call_arg_meta *meta)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
|
|
|
|
switch (reg->type) {
|
|
case PTR_TO_PACKET:
|
|
case PTR_TO_PACKET_META:
|
|
return check_packet_access(env, regno, reg->off, access_size,
|
|
zero_size_allowed);
|
|
case PTR_TO_MAP_VALUE:
|
|
return check_map_access(env, regno, reg->off, access_size,
|
|
zero_size_allowed);
|
|
default: /* scalar_value|ptr_to_stack or invalid ptr */
|
|
return check_stack_boundary(env, regno, access_size,
|
|
zero_size_allowed, meta);
|
|
}
|
|
}
|
|
|
|
static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
|
|
{
|
|
return type == ARG_PTR_TO_MEM ||
|
|
type == ARG_PTR_TO_MEM_OR_NULL ||
|
|
type == ARG_PTR_TO_UNINIT_MEM;
|
|
}
|
|
|
|
static bool arg_type_is_mem_size(enum bpf_arg_type type)
|
|
{
|
|
return type == ARG_CONST_SIZE ||
|
|
type == ARG_CONST_SIZE_OR_ZERO;
|
|
}
|
|
|
|
static int check_func_arg(struct bpf_verifier_env *env, u32 regno,
|
|
enum bpf_arg_type arg_type,
|
|
struct bpf_call_arg_meta *meta)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
|
|
enum bpf_reg_type expected_type, type = reg->type;
|
|
int err = 0;
|
|
|
|
if (arg_type == ARG_DONTCARE)
|
|
return 0;
|
|
|
|
err = check_reg_arg(env, regno, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (arg_type == ARG_ANYTHING) {
|
|
if (is_pointer_value(env, regno)) {
|
|
verbose(env, "R%d leaks addr into helper function\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
if (type_is_pkt_pointer(type) &&
|
|
!may_access_direct_pkt_data(env, meta, BPF_READ)) {
|
|
verbose(env, "helper access to the packet is not allowed\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
if (arg_type == ARG_PTR_TO_MAP_KEY ||
|
|
arg_type == ARG_PTR_TO_MAP_VALUE) {
|
|
expected_type = PTR_TO_STACK;
|
|
if (!type_is_pkt_pointer(type) && type != PTR_TO_MAP_VALUE &&
|
|
type != expected_type)
|
|
goto err_type;
|
|
} else if (arg_type == ARG_CONST_SIZE ||
|
|
arg_type == ARG_CONST_SIZE_OR_ZERO) {
|
|
expected_type = SCALAR_VALUE;
|
|
if (type != expected_type)
|
|
goto err_type;
|
|
} else if (arg_type == ARG_CONST_MAP_PTR) {
|
|
expected_type = CONST_PTR_TO_MAP;
|
|
if (type != expected_type)
|
|
goto err_type;
|
|
} else if (arg_type == ARG_PTR_TO_CTX) {
|
|
expected_type = PTR_TO_CTX;
|
|
if (type != expected_type)
|
|
goto err_type;
|
|
err = check_ctx_reg(env, reg, regno);
|
|
if (err < 0)
|
|
return err;
|
|
} else if (arg_type_is_mem_ptr(arg_type)) {
|
|
expected_type = PTR_TO_STACK;
|
|
/* One exception here. In case function allows for NULL to be
|
|
* passed in as argument, it's a SCALAR_VALUE type. Final test
|
|
* happens during stack boundary checking.
|
|
*/
|
|
if (register_is_null(reg) &&
|
|
arg_type == ARG_PTR_TO_MEM_OR_NULL)
|
|
/* final test in check_stack_boundary() */;
|
|
else if (!type_is_pkt_pointer(type) &&
|
|
type != PTR_TO_MAP_VALUE &&
|
|
type != expected_type)
|
|
goto err_type;
|
|
meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM;
|
|
} else {
|
|
verbose(env, "unsupported arg_type %d\n", arg_type);
|
|
return -EFAULT;
|
|
}
|
|
|
|
if (arg_type == ARG_CONST_MAP_PTR) {
|
|
/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
|
|
meta->map_ptr = reg->map_ptr;
|
|
} else if (arg_type == ARG_PTR_TO_MAP_KEY) {
|
|
/* bpf_map_xxx(..., map_ptr, ..., key) call:
|
|
* check that [key, key + map->key_size) are within
|
|
* stack limits and initialized
|
|
*/
|
|
if (!meta->map_ptr) {
|
|
/* in function declaration map_ptr must come before
|
|
* map_key, so that it's verified and known before
|
|
* we have to check map_key here. Otherwise it means
|
|
* that kernel subsystem misconfigured verifier
|
|
*/
|
|
verbose(env, "invalid map_ptr to access map->key\n");
|
|
return -EACCES;
|
|
}
|
|
err = check_helper_mem_access(env, regno,
|
|
meta->map_ptr->key_size, false,
|
|
NULL);
|
|
} else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
|
|
/* bpf_map_xxx(..., map_ptr, ..., value) call:
|
|
* check [value, value + map->value_size) validity
|
|
*/
|
|
if (!meta->map_ptr) {
|
|
/* kernel subsystem misconfigured verifier */
|
|
verbose(env, "invalid map_ptr to access map->value\n");
|
|
return -EACCES;
|
|
}
|
|
err = check_helper_mem_access(env, regno,
|
|
meta->map_ptr->value_size, false,
|
|
NULL);
|
|
} else if (arg_type_is_mem_size(arg_type)) {
|
|
bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
|
|
|
|
/* remember the mem_size which may be used later
|
|
* to refine return values.
|
|
*/
|
|
meta->msize_max_value = reg->umax_value;
|
|
|
|
/* The register is SCALAR_VALUE; the access check
|
|
* happens using its boundaries.
|
|
*/
|
|
if (!tnum_is_const(reg->var_off))
|
|
/* For unprivileged variable accesses, disable raw
|
|
* mode so that the program is required to
|
|
* initialize all the memory that the helper could
|
|
* just partially fill up.
|
|
*/
|
|
meta = NULL;
|
|
|
|
if (reg->smin_value < 0) {
|
|
verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (reg->umin_value == 0) {
|
|
err = check_helper_mem_access(env, regno - 1, 0,
|
|
zero_size_allowed,
|
|
meta);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
|
|
verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
|
|
regno);
|
|
return -EACCES;
|
|
}
|
|
err = check_helper_mem_access(env, regno - 1,
|
|
reg->umax_value,
|
|
zero_size_allowed, meta);
|
|
}
|
|
|
|
return err;
|
|
err_type:
|
|
verbose(env, "R%d type=%s expected=%s\n", regno,
|
|
reg_type_str[type], reg_type_str[expected_type]);
|
|
return -EACCES;
|
|
}
|
|
|
|
static int check_map_func_compatibility(struct bpf_verifier_env *env,
|
|
struct bpf_map *map, int func_id)
|
|
{
|
|
if (!map)
|
|
return 0;
|
|
|
|
/* We need a two way check, first is from map perspective ... */
|
|
switch (map->map_type) {
|
|
case BPF_MAP_TYPE_PROG_ARRAY:
|
|
if (func_id != BPF_FUNC_tail_call)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
|
|
if (func_id != BPF_FUNC_perf_event_read &&
|
|
func_id != BPF_FUNC_perf_event_output &&
|
|
func_id != BPF_FUNC_perf_event_read_value)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_STACK_TRACE:
|
|
if (func_id != BPF_FUNC_get_stackid)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_CGROUP_ARRAY:
|
|
if (func_id != BPF_FUNC_skb_under_cgroup &&
|
|
func_id != BPF_FUNC_current_task_under_cgroup)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_CGROUP_STORAGE:
|
|
if (func_id != BPF_FUNC_get_local_storage)
|
|
goto error;
|
|
break;
|
|
/* devmap returns a pointer to a live net_device ifindex that we cannot
|
|
* allow to be modified from bpf side. So do not allow lookup elements
|
|
* for now.
|
|
*/
|
|
case BPF_MAP_TYPE_DEVMAP:
|
|
if (func_id != BPF_FUNC_redirect_map)
|
|
goto error;
|
|
break;
|
|
/* Restrict bpf side of cpumap and xskmap, open when use-cases
|
|
* appear.
|
|
*/
|
|
case BPF_MAP_TYPE_CPUMAP:
|
|
case BPF_MAP_TYPE_XSKMAP:
|
|
if (func_id != BPF_FUNC_redirect_map)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
|
|
case BPF_MAP_TYPE_HASH_OF_MAPS:
|
|
if (func_id != BPF_FUNC_map_lookup_elem)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_SOCKMAP:
|
|
if (func_id != BPF_FUNC_sk_redirect_map &&
|
|
func_id != BPF_FUNC_sock_map_update &&
|
|
func_id != BPF_FUNC_map_delete_elem &&
|
|
func_id != BPF_FUNC_msg_redirect_map)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_SOCKHASH:
|
|
if (func_id != BPF_FUNC_sk_redirect_hash &&
|
|
func_id != BPF_FUNC_sock_hash_update &&
|
|
func_id != BPF_FUNC_map_delete_elem &&
|
|
func_id != BPF_FUNC_msg_redirect_hash)
|
|
goto error;
|
|
break;
|
|
case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
|
|
if (func_id != BPF_FUNC_sk_select_reuseport)
|
|
goto error;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
/* ... and second from the function itself. */
|
|
switch (func_id) {
|
|
case BPF_FUNC_tail_call:
|
|
if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
|
|
goto error;
|
|
if (env->subprog_cnt > 1) {
|
|
verbose(env, "tail_calls are not allowed in programs with bpf-to-bpf calls\n");
|
|
return -EINVAL;
|
|
}
|
|
break;
|
|
case BPF_FUNC_perf_event_read:
|
|
case BPF_FUNC_perf_event_output:
|
|
case BPF_FUNC_perf_event_read_value:
|
|
if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_get_stackid:
|
|
if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_current_task_under_cgroup:
|
|
case BPF_FUNC_skb_under_cgroup:
|
|
if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_redirect_map:
|
|
if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
|
|
map->map_type != BPF_MAP_TYPE_CPUMAP &&
|
|
map->map_type != BPF_MAP_TYPE_XSKMAP)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_sk_redirect_map:
|
|
case BPF_FUNC_msg_redirect_map:
|
|
case BPF_FUNC_sock_map_update:
|
|
if (map->map_type != BPF_MAP_TYPE_SOCKMAP)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_sk_redirect_hash:
|
|
case BPF_FUNC_msg_redirect_hash:
|
|
case BPF_FUNC_sock_hash_update:
|
|
if (map->map_type != BPF_MAP_TYPE_SOCKHASH)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_get_local_storage:
|
|
if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE)
|
|
goto error;
|
|
break;
|
|
case BPF_FUNC_sk_select_reuseport:
|
|
if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY)
|
|
goto error;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
error:
|
|
verbose(env, "cannot pass map_type %d into func %s#%d\n",
|
|
map->map_type, func_id_name(func_id), func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
|
|
{
|
|
int count = 0;
|
|
|
|
if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
|
|
count++;
|
|
|
|
/* We only support one arg being in raw mode at the moment,
|
|
* which is sufficient for the helper functions we have
|
|
* right now.
|
|
*/
|
|
return count <= 1;
|
|
}
|
|
|
|
static bool check_args_pair_invalid(enum bpf_arg_type arg_curr,
|
|
enum bpf_arg_type arg_next)
|
|
{
|
|
return (arg_type_is_mem_ptr(arg_curr) &&
|
|
!arg_type_is_mem_size(arg_next)) ||
|
|
(!arg_type_is_mem_ptr(arg_curr) &&
|
|
arg_type_is_mem_size(arg_next));
|
|
}
|
|
|
|
static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
|
|
{
|
|
/* bpf_xxx(..., buf, len) call will access 'len'
|
|
* bytes from memory 'buf'. Both arg types need
|
|
* to be paired, so make sure there's no buggy
|
|
* helper function specification.
|
|
*/
|
|
if (arg_type_is_mem_size(fn->arg1_type) ||
|
|
arg_type_is_mem_ptr(fn->arg5_type) ||
|
|
check_args_pair_invalid(fn->arg1_type, fn->arg2_type) ||
|
|
check_args_pair_invalid(fn->arg2_type, fn->arg3_type) ||
|
|
check_args_pair_invalid(fn->arg3_type, fn->arg4_type) ||
|
|
check_args_pair_invalid(fn->arg4_type, fn->arg5_type))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static int check_func_proto(const struct bpf_func_proto *fn)
|
|
{
|
|
return check_raw_mode_ok(fn) &&
|
|
check_arg_pair_ok(fn) ? 0 : -EINVAL;
|
|
}
|
|
|
|
/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
|
|
* are now invalid, so turn them into unknown SCALAR_VALUE.
|
|
*/
|
|
static void __clear_all_pkt_pointers(struct bpf_verifier_env *env,
|
|
struct bpf_func_state *state)
|
|
{
|
|
struct bpf_reg_state *regs = state->regs, *reg;
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++)
|
|
if (reg_is_pkt_pointer_any(®s[i]))
|
|
mark_reg_unknown(env, regs, i);
|
|
|
|
for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
|
|
if (state->stack[i].slot_type[0] != STACK_SPILL)
|
|
continue;
|
|
reg = &state->stack[i].spilled_ptr;
|
|
if (reg_is_pkt_pointer_any(reg))
|
|
__mark_reg_unknown(reg);
|
|
}
|
|
}
|
|
|
|
static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_verifier_state *vstate = env->cur_state;
|
|
int i;
|
|
|
|
for (i = 0; i <= vstate->curframe; i++)
|
|
__clear_all_pkt_pointers(env, vstate->frame[i]);
|
|
}
|
|
|
|
static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
|
|
int *insn_idx)
|
|
{
|
|
struct bpf_verifier_state *state = env->cur_state;
|
|
struct bpf_func_state *caller, *callee;
|
|
int i, subprog, target_insn;
|
|
|
|
if (state->curframe + 1 >= MAX_CALL_FRAMES) {
|
|
verbose(env, "the call stack of %d frames is too deep\n",
|
|
state->curframe + 2);
|
|
return -E2BIG;
|
|
}
|
|
|
|
target_insn = *insn_idx + insn->imm;
|
|
subprog = find_subprog(env, target_insn + 1);
|
|
if (subprog < 0) {
|
|
verbose(env, "verifier bug. No program starts at insn %d\n",
|
|
target_insn + 1);
|
|
return -EFAULT;
|
|
}
|
|
|
|
caller = state->frame[state->curframe];
|
|
if (state->frame[state->curframe + 1]) {
|
|
verbose(env, "verifier bug. Frame %d already allocated\n",
|
|
state->curframe + 1);
|
|
return -EFAULT;
|
|
}
|
|
|
|
callee = kzalloc(sizeof(*callee), GFP_KERNEL);
|
|
if (!callee)
|
|
return -ENOMEM;
|
|
state->frame[state->curframe + 1] = callee;
|
|
|
|
/* callee cannot access r0, r6 - r9 for reading and has to write
|
|
* into its own stack before reading from it.
|
|
* callee can read/write into caller's stack
|
|
*/
|
|
init_func_state(env, callee,
|
|
/* remember the callsite, it will be used by bpf_exit */
|
|
*insn_idx /* callsite */,
|
|
state->curframe + 1 /* frameno within this callchain */,
|
|
subprog /* subprog number within this prog */);
|
|
|
|
/* copy r1 - r5 args that callee can access */
|
|
for (i = BPF_REG_1; i <= BPF_REG_5; i++)
|
|
callee->regs[i] = caller->regs[i];
|
|
|
|
/* after the call regsiters r0 - r5 were scratched */
|
|
for (i = 0; i < CALLER_SAVED_REGS; i++) {
|
|
mark_reg_not_init(env, caller->regs, caller_saved[i]);
|
|
check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
|
|
}
|
|
|
|
/* only increment it after check_reg_arg() finished */
|
|
state->curframe++;
|
|
|
|
/* and go analyze first insn of the callee */
|
|
*insn_idx = target_insn;
|
|
|
|
if (env->log.level) {
|
|
verbose(env, "caller:\n");
|
|
print_verifier_state(env, caller);
|
|
verbose(env, "callee:\n");
|
|
print_verifier_state(env, callee);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
|
|
{
|
|
struct bpf_verifier_state *state = env->cur_state;
|
|
struct bpf_func_state *caller, *callee;
|
|
struct bpf_reg_state *r0;
|
|
|
|
callee = state->frame[state->curframe];
|
|
r0 = &callee->regs[BPF_REG_0];
|
|
if (r0->type == PTR_TO_STACK) {
|
|
/* technically it's ok to return caller's stack pointer
|
|
* (or caller's caller's pointer) back to the caller,
|
|
* since these pointers are valid. Only current stack
|
|
* pointer will be invalid as soon as function exits,
|
|
* but let's be conservative
|
|
*/
|
|
verbose(env, "cannot return stack pointer to the caller\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
state->curframe--;
|
|
caller = state->frame[state->curframe];
|
|
/* return to the caller whatever r0 had in the callee */
|
|
caller->regs[BPF_REG_0] = *r0;
|
|
|
|
*insn_idx = callee->callsite + 1;
|
|
if (env->log.level) {
|
|
verbose(env, "returning from callee:\n");
|
|
print_verifier_state(env, callee);
|
|
verbose(env, "to caller at %d:\n", *insn_idx);
|
|
print_verifier_state(env, caller);
|
|
}
|
|
/* clear everything in the callee */
|
|
free_func_state(callee);
|
|
state->frame[state->curframe + 1] = NULL;
|
|
return 0;
|
|
}
|
|
|
|
static int do_refine_retval_range(struct bpf_verifier_env *env,
|
|
struct bpf_reg_state *regs, int ret_type,
|
|
int func_id, struct bpf_call_arg_meta *meta)
|
|
{
|
|
struct bpf_reg_state *ret_reg = ®s[BPF_REG_0];
|
|
struct bpf_reg_state tmp_reg = *ret_reg;
|
|
bool ret;
|
|
|
|
if (ret_type != RET_INTEGER ||
|
|
(func_id != BPF_FUNC_get_stack &&
|
|
func_id != BPF_FUNC_probe_read_str))
|
|
return 0;
|
|
|
|
/* Error case where ret is in interval [S32MIN, -1]. */
|
|
ret_reg->smin_value = S32_MIN;
|
|
ret_reg->smax_value = -1;
|
|
|
|
__reg_deduce_bounds(ret_reg);
|
|
__reg_bound_offset(ret_reg);
|
|
__update_reg_bounds(ret_reg);
|
|
|
|
ret = push_stack(env, env->insn_idx + 1, env->insn_idx, false);
|
|
if (!ret)
|
|
return -EFAULT;
|
|
|
|
*ret_reg = tmp_reg;
|
|
|
|
/* Success case where ret is in range [0, msize_max_value]. */
|
|
ret_reg->smin_value = 0;
|
|
ret_reg->smax_value = meta->msize_max_value;
|
|
ret_reg->umin_value = ret_reg->smin_value;
|
|
ret_reg->umax_value = ret_reg->smax_value;
|
|
|
|
__reg_deduce_bounds(ret_reg);
|
|
__reg_bound_offset(ret_reg);
|
|
__update_reg_bounds(ret_reg);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
|
|
int func_id, int insn_idx)
|
|
{
|
|
struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
|
|
|
|
if (func_id != BPF_FUNC_tail_call &&
|
|
func_id != BPF_FUNC_map_lookup_elem &&
|
|
func_id != BPF_FUNC_map_update_elem &&
|
|
func_id != BPF_FUNC_map_delete_elem)
|
|
return 0;
|
|
|
|
if (meta->map_ptr == NULL) {
|
|
verbose(env, "kernel subsystem misconfigured verifier\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!BPF_MAP_PTR(aux->map_state))
|
|
bpf_map_ptr_store(aux, meta->map_ptr,
|
|
meta->map_ptr->unpriv_array);
|
|
else if (BPF_MAP_PTR(aux->map_state) != meta->map_ptr)
|
|
bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON,
|
|
meta->map_ptr->unpriv_array);
|
|
return 0;
|
|
}
|
|
|
|
static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
|
|
{
|
|
const struct bpf_func_proto *fn = NULL;
|
|
struct bpf_reg_state *regs;
|
|
struct bpf_call_arg_meta meta;
|
|
bool changes_data;
|
|
int i, err;
|
|
|
|
/* find function prototype */
|
|
if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
|
|
verbose(env, "invalid func %s#%d\n", func_id_name(func_id),
|
|
func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (env->ops->get_func_proto)
|
|
fn = env->ops->get_func_proto(func_id, env->prog);
|
|
if (!fn) {
|
|
verbose(env, "unknown func %s#%d\n", func_id_name(func_id),
|
|
func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* eBPF programs must be GPL compatible to use GPL-ed functions */
|
|
if (!env->prog->gpl_compatible && fn->gpl_only) {
|
|
verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* With LD_ABS/IND some JITs save/restore skb from r1. */
|
|
changes_data = bpf_helper_changes_pkt_data(fn->func);
|
|
if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
|
|
verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
|
|
func_id_name(func_id), func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
memset(&meta, 0, sizeof(meta));
|
|
meta.pkt_access = fn->pkt_access;
|
|
|
|
err = check_func_proto(fn);
|
|
if (err) {
|
|
verbose(env, "kernel subsystem misconfigured func %s#%d\n",
|
|
func_id_name(func_id), func_id);
|
|
return err;
|
|
}
|
|
|
|
/* check args */
|
|
err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &meta);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &meta);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &meta);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &meta);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &meta);
|
|
if (err)
|
|
return err;
|
|
|
|
err = record_func_map(env, &meta, func_id, insn_idx);
|
|
if (err)
|
|
return err;
|
|
|
|
/* Mark slots with STACK_MISC in case of raw mode, stack offset
|
|
* is inferred from register state.
|
|
*/
|
|
for (i = 0; i < meta.access_size; i++) {
|
|
err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B,
|
|
BPF_WRITE, -1, false);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
regs = cur_regs(env);
|
|
|
|
/* check that flags argument in get_local_storage(map, flags) is 0,
|
|
* this is required because get_local_storage() can't return an error.
|
|
*/
|
|
if (func_id == BPF_FUNC_get_local_storage &&
|
|
!register_is_null(®s[BPF_REG_2])) {
|
|
verbose(env, "get_local_storage() doesn't support non-zero flags\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* reset caller saved regs */
|
|
for (i = 0; i < CALLER_SAVED_REGS; i++) {
|
|
mark_reg_not_init(env, regs, caller_saved[i]);
|
|
check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
|
|
}
|
|
|
|
/* update return register (already marked as written above) */
|
|
if (fn->ret_type == RET_INTEGER) {
|
|
/* sets type to SCALAR_VALUE */
|
|
mark_reg_unknown(env, regs, BPF_REG_0);
|
|
} else if (fn->ret_type == RET_VOID) {
|
|
regs[BPF_REG_0].type = NOT_INIT;
|
|
} else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL ||
|
|
fn->ret_type == RET_PTR_TO_MAP_VALUE) {
|
|
if (fn->ret_type == RET_PTR_TO_MAP_VALUE)
|
|
regs[BPF_REG_0].type = PTR_TO_MAP_VALUE;
|
|
else
|
|
regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
|
|
/* There is no offset yet applied, variable or fixed */
|
|
mark_reg_known_zero(env, regs, BPF_REG_0);
|
|
/* remember map_ptr, so that check_map_access()
|
|
* can check 'value_size' boundary of memory access
|
|
* to map element returned from bpf_map_lookup_elem()
|
|
*/
|
|
if (meta.map_ptr == NULL) {
|
|
verbose(env,
|
|
"kernel subsystem misconfigured verifier\n");
|
|
return -EINVAL;
|
|
}
|
|
regs[BPF_REG_0].map_ptr = meta.map_ptr;
|
|
regs[BPF_REG_0].id = ++env->id_gen;
|
|
} else {
|
|
verbose(env, "unknown return type %d of func %s#%d\n",
|
|
fn->ret_type, func_id_name(func_id), func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
err = do_refine_retval_range(env, regs, fn->ret_type, func_id, &meta);
|
|
if (err)
|
|
return err;
|
|
|
|
err = check_map_func_compatibility(env, meta.map_ptr, func_id);
|
|
if (err)
|
|
return err;
|
|
|
|
if (func_id == BPF_FUNC_get_stack && !env->prog->has_callchain_buf) {
|
|
const char *err_str;
|
|
|
|
#ifdef CONFIG_PERF_EVENTS
|
|
err = get_callchain_buffers(sysctl_perf_event_max_stack);
|
|
err_str = "cannot get callchain buffer for func %s#%d\n";
|
|
#else
|
|
err = -ENOTSUPP;
|
|
err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
|
|
#endif
|
|
if (err) {
|
|
verbose(env, err_str, func_id_name(func_id), func_id);
|
|
return err;
|
|
}
|
|
|
|
env->prog->has_callchain_buf = true;
|
|
}
|
|
|
|
if (changes_data)
|
|
clear_all_pkt_pointers(env);
|
|
return 0;
|
|
}
|
|
|
|
static bool signed_add_overflows(s64 a, s64 b)
|
|
{
|
|
/* Do the add in u64, where overflow is well-defined */
|
|
s64 res = (s64)((u64)a + (u64)b);
|
|
|
|
if (b < 0)
|
|
return res > a;
|
|
return res < a;
|
|
}
|
|
|
|
static bool signed_sub_overflows(s64 a, s64 b)
|
|
{
|
|
/* Do the sub in u64, where overflow is well-defined */
|
|
s64 res = (s64)((u64)a - (u64)b);
|
|
|
|
if (b < 0)
|
|
return res < a;
|
|
return res > a;
|
|
}
|
|
|
|
static bool check_reg_sane_offset(struct bpf_verifier_env *env,
|
|
const struct bpf_reg_state *reg,
|
|
enum bpf_reg_type type)
|
|
{
|
|
bool known = tnum_is_const(reg->var_off);
|
|
s64 val = reg->var_off.value;
|
|
s64 smin = reg->smin_value;
|
|
|
|
if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
|
|
verbose(env, "math between %s pointer and %lld is not allowed\n",
|
|
reg_type_str[type], val);
|
|
return false;
|
|
}
|
|
|
|
if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
|
|
verbose(env, "%s pointer offset %d is not allowed\n",
|
|
reg_type_str[type], reg->off);
|
|
return false;
|
|
}
|
|
|
|
if (smin == S64_MIN) {
|
|
verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
|
|
reg_type_str[type]);
|
|
return false;
|
|
}
|
|
|
|
if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
|
|
verbose(env, "value %lld makes %s pointer be out of bounds\n",
|
|
smin, reg_type_str[type]);
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env)
|
|
{
|
|
return &env->insn_aux_data[env->insn_idx];
|
|
}
|
|
|
|
static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
|
|
u32 *ptr_limit, u8 opcode, bool off_is_neg)
|
|
{
|
|
bool mask_to_left = (opcode == BPF_ADD && off_is_neg) ||
|
|
(opcode == BPF_SUB && !off_is_neg);
|
|
u32 off, max;
|
|
|
|
switch (ptr_reg->type) {
|
|
case PTR_TO_STACK:
|
|
/* Offset 0 is out-of-bounds, but acceptable start for the
|
|
* left direction, see BPF_REG_FP.
|
|
*/
|
|
max = MAX_BPF_STACK + mask_to_left;
|
|
off = ptr_reg->off + ptr_reg->var_off.value;
|
|
if (mask_to_left)
|
|
*ptr_limit = MAX_BPF_STACK + off;
|
|
else
|
|
*ptr_limit = -off - 1;
|
|
return *ptr_limit >= max ? -ERANGE : 0;
|
|
case PTR_TO_MAP_VALUE:
|
|
max = ptr_reg->map_ptr->value_size;
|
|
if (mask_to_left) {
|
|
*ptr_limit = ptr_reg->umax_value + ptr_reg->off;
|
|
} else {
|
|
off = ptr_reg->smin_value + ptr_reg->off;
|
|
*ptr_limit = ptr_reg->map_ptr->value_size - off - 1;
|
|
}
|
|
return *ptr_limit >= max ? -ERANGE : 0;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env,
|
|
const struct bpf_insn *insn)
|
|
{
|
|
return env->allow_ptr_leaks || BPF_SRC(insn->code) == BPF_K;
|
|
}
|
|
|
|
static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux,
|
|
u32 alu_state, u32 alu_limit)
|
|
{
|
|
/* If we arrived here from different branches with different
|
|
* state or limits to sanitize, then this won't work.
|
|
*/
|
|
if (aux->alu_state &&
|
|
(aux->alu_state != alu_state ||
|
|
aux->alu_limit != alu_limit))
|
|
return -EACCES;
|
|
|
|
/* Corresponding fixup done in fixup_bpf_calls(). */
|
|
aux->alu_state = alu_state;
|
|
aux->alu_limit = alu_limit;
|
|
return 0;
|
|
}
|
|
|
|
static int sanitize_val_alu(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn)
|
|
{
|
|
struct bpf_insn_aux_data *aux = cur_aux(env);
|
|
|
|
if (can_skip_alu_sanitation(env, insn))
|
|
return 0;
|
|
|
|
return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
|
|
}
|
|
|
|
static int sanitize_ptr_alu(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn,
|
|
const struct bpf_reg_state *ptr_reg,
|
|
struct bpf_reg_state *dst_reg,
|
|
bool off_is_neg)
|
|
{
|
|
struct bpf_verifier_state *vstate = env->cur_state;
|
|
struct bpf_insn_aux_data *aux = cur_aux(env);
|
|
bool ptr_is_dst_reg = ptr_reg == dst_reg;
|
|
u8 opcode = BPF_OP(insn->code);
|
|
u32 alu_state, alu_limit;
|
|
struct bpf_reg_state tmp;
|
|
bool ret;
|
|
int err;
|
|
|
|
if (can_skip_alu_sanitation(env, insn))
|
|
return 0;
|
|
|
|
/* We already marked aux for masking from non-speculative
|
|
* paths, thus we got here in the first place. We only care
|
|
* to explore bad access from here.
|
|
*/
|
|
if (vstate->speculative)
|
|
goto do_sim;
|
|
|
|
alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
|
|
alu_state |= ptr_is_dst_reg ?
|
|
BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;
|
|
|
|
err = retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
err = update_alu_sanitation_state(aux, alu_state, alu_limit);
|
|
if (err < 0)
|
|
return err;
|
|
do_sim:
|
|
/* Simulate and find potential out-of-bounds access under
|
|
* speculative execution from truncation as a result of
|
|
* masking when off was not within expected range. If off
|
|
* sits in dst, then we temporarily need to move ptr there
|
|
* to simulate dst (== 0) +/-= ptr. Needed, for example,
|
|
* for cases where we use K-based arithmetic in one direction
|
|
* and truncated reg-based in the other in order to explore
|
|
* bad access.
|
|
*/
|
|
if (!ptr_is_dst_reg) {
|
|
tmp = *dst_reg;
|
|
*dst_reg = *ptr_reg;
|
|
}
|
|
ret = push_stack(env, env->insn_idx + 1, env->insn_idx, true);
|
|
if (!ptr_is_dst_reg && ret)
|
|
*dst_reg = tmp;
|
|
return !ret ? -EFAULT : 0;
|
|
}
|
|
|
|
/* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
|
|
* Caller should also handle BPF_MOV case separately.
|
|
* If we return -EACCES, caller may want to try again treating pointer as a
|
|
* scalar. So we only emit a diagnostic if !env->allow_ptr_leaks.
|
|
*/
|
|
static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn,
|
|
const struct bpf_reg_state *ptr_reg,
|
|
const struct bpf_reg_state *off_reg)
|
|
{
|
|
struct bpf_verifier_state *vstate = env->cur_state;
|
|
struct bpf_func_state *state = vstate->frame[vstate->curframe];
|
|
struct bpf_reg_state *regs = state->regs, *dst_reg;
|
|
bool known = tnum_is_const(off_reg->var_off);
|
|
s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
|
|
smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
|
|
u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
|
|
umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
|
|
u32 dst = insn->dst_reg, src = insn->src_reg;
|
|
u8 opcode = BPF_OP(insn->code);
|
|
int ret;
|
|
|
|
dst_reg = ®s[dst];
|
|
|
|
if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
|
|
smin_val > smax_val || umin_val > umax_val) {
|
|
/* Taint dst register if offset had invalid bounds derived from
|
|
* e.g. dead branches.
|
|
*/
|
|
__mark_reg_unknown(dst_reg);
|
|
return 0;
|
|
}
|
|
|
|
if (BPF_CLASS(insn->code) != BPF_ALU64) {
|
|
/* 32-bit ALU ops on pointers produce (meaningless) scalars */
|
|
verbose(env,
|
|
"R%d 32-bit pointer arithmetic prohibited\n",
|
|
dst);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (ptr_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
|
|
verbose(env, "R%d pointer arithmetic on PTR_TO_MAP_VALUE_OR_NULL prohibited, null-check it first\n",
|
|
dst);
|
|
return -EACCES;
|
|
}
|
|
if (ptr_reg->type == CONST_PTR_TO_MAP) {
|
|
verbose(env, "R%d pointer arithmetic on CONST_PTR_TO_MAP prohibited\n",
|
|
dst);
|
|
return -EACCES;
|
|
}
|
|
if (ptr_reg->type == PTR_TO_PACKET_END) {
|
|
verbose(env, "R%d pointer arithmetic on PTR_TO_PACKET_END prohibited\n",
|
|
dst);
|
|
return -EACCES;
|
|
}
|
|
if (ptr_reg->type == PTR_TO_MAP_VALUE &&
|
|
!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) {
|
|
verbose(env, "R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n",
|
|
off_reg == dst_reg ? dst : src);
|
|
return -EACCES;
|
|
}
|
|
|
|
/* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
|
|
* The id may be overwritten later if we create a new variable offset.
|
|
*/
|
|
dst_reg->type = ptr_reg->type;
|
|
dst_reg->id = ptr_reg->id;
|
|
|
|
if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) ||
|
|
!check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
|
|
return -EINVAL;
|
|
|
|
switch (opcode) {
|
|
case BPF_ADD:
|
|
ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
|
|
if (ret < 0) {
|
|
verbose(env, "R%d tried to add from different maps, paths, or prohibited types\n", dst);
|
|
return ret;
|
|
}
|
|
/* We can take a fixed offset as long as it doesn't overflow
|
|
* the s32 'off' field
|
|
*/
|
|
if (known && (ptr_reg->off + smin_val ==
|
|
(s64)(s32)(ptr_reg->off + smin_val))) {
|
|
/* pointer += K. Accumulate it into fixed offset */
|
|
dst_reg->smin_value = smin_ptr;
|
|
dst_reg->smax_value = smax_ptr;
|
|
dst_reg->umin_value = umin_ptr;
|
|
dst_reg->umax_value = umax_ptr;
|
|
dst_reg->var_off = ptr_reg->var_off;
|
|
dst_reg->off = ptr_reg->off + smin_val;
|
|
dst_reg->raw = ptr_reg->raw;
|
|
break;
|
|
}
|
|
/* A new variable offset is created. Note that off_reg->off
|
|
* == 0, since it's a scalar.
|
|
* dst_reg gets the pointer type and since some positive
|
|
* integer value was added to the pointer, give it a new 'id'
|
|
* if it's a PTR_TO_PACKET.
|
|
* this creates a new 'base' pointer, off_reg (variable) gets
|
|
* added into the variable offset, and we copy the fixed offset
|
|
* from ptr_reg.
|
|
*/
|
|
if (signed_add_overflows(smin_ptr, smin_val) ||
|
|
signed_add_overflows(smax_ptr, smax_val)) {
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
} else {
|
|
dst_reg->smin_value = smin_ptr + smin_val;
|
|
dst_reg->smax_value = smax_ptr + smax_val;
|
|
}
|
|
if (umin_ptr + umin_val < umin_ptr ||
|
|
umax_ptr + umax_val < umax_ptr) {
|
|
dst_reg->umin_value = 0;
|
|
dst_reg->umax_value = U64_MAX;
|
|
} else {
|
|
dst_reg->umin_value = umin_ptr + umin_val;
|
|
dst_reg->umax_value = umax_ptr + umax_val;
|
|
}
|
|
dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
|
|
dst_reg->off = ptr_reg->off;
|
|
dst_reg->raw = ptr_reg->raw;
|
|
if (reg_is_pkt_pointer(ptr_reg)) {
|
|
dst_reg->id = ++env->id_gen;
|
|
/* something was added to pkt_ptr, set range to zero */
|
|
dst_reg->raw = 0;
|
|
}
|
|
break;
|
|
case BPF_SUB:
|
|
ret = sanitize_ptr_alu(env, insn, ptr_reg, dst_reg, smin_val < 0);
|
|
if (ret < 0) {
|
|
verbose(env, "R%d tried to sub from different maps, paths, or prohibited types\n", dst);
|
|
return ret;
|
|
}
|
|
if (dst_reg == off_reg) {
|
|
/* scalar -= pointer. Creates an unknown scalar */
|
|
verbose(env, "R%d tried to subtract pointer from scalar\n",
|
|
dst);
|
|
return -EACCES;
|
|
}
|
|
/* We don't allow subtraction from FP, because (according to
|
|
* test_verifier.c test "invalid fp arithmetic", JITs might not
|
|
* be able to deal with it.
|
|
*/
|
|
if (ptr_reg->type == PTR_TO_STACK) {
|
|
verbose(env, "R%d subtraction from stack pointer prohibited\n",
|
|
dst);
|
|
return -EACCES;
|
|
}
|
|
if (known && (ptr_reg->off - smin_val ==
|
|
(s64)(s32)(ptr_reg->off - smin_val))) {
|
|
/* pointer -= K. Subtract it from fixed offset */
|
|
dst_reg->smin_value = smin_ptr;
|
|
dst_reg->smax_value = smax_ptr;
|
|
dst_reg->umin_value = umin_ptr;
|
|
dst_reg->umax_value = umax_ptr;
|
|
dst_reg->var_off = ptr_reg->var_off;
|
|
dst_reg->id = ptr_reg->id;
|
|
dst_reg->off = ptr_reg->off - smin_val;
|
|
dst_reg->raw = ptr_reg->raw;
|
|
break;
|
|
}
|
|
/* A new variable offset is created. If the subtrahend is known
|
|
* nonnegative, then any reg->range we had before is still good.
|
|
*/
|
|
if (signed_sub_overflows(smin_ptr, smax_val) ||
|
|
signed_sub_overflows(smax_ptr, smin_val)) {
|
|
/* Overflow possible, we know nothing */
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
} else {
|
|
dst_reg->smin_value = smin_ptr - smax_val;
|
|
dst_reg->smax_value = smax_ptr - smin_val;
|
|
}
|
|
if (umin_ptr < umax_val) {
|
|
/* Overflow possible, we know nothing */
|
|
dst_reg->umin_value = 0;
|
|
dst_reg->umax_value = U64_MAX;
|
|
} else {
|
|
/* Cannot overflow (as long as bounds are consistent) */
|
|
dst_reg->umin_value = umin_ptr - umax_val;
|
|
dst_reg->umax_value = umax_ptr - umin_val;
|
|
}
|
|
dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
|
|
dst_reg->off = ptr_reg->off;
|
|
dst_reg->raw = ptr_reg->raw;
|
|
if (reg_is_pkt_pointer(ptr_reg)) {
|
|
dst_reg->id = ++env->id_gen;
|
|
/* something was added to pkt_ptr, set range to zero */
|
|
if (smin_val < 0)
|
|
dst_reg->raw = 0;
|
|
}
|
|
break;
|
|
case BPF_AND:
|
|
case BPF_OR:
|
|
case BPF_XOR:
|
|
/* bitwise ops on pointers are troublesome, prohibit. */
|
|
verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
|
|
dst, bpf_alu_string[opcode >> 4]);
|
|
return -EACCES;
|
|
default:
|
|
/* other operators (e.g. MUL,LSH) produce non-pointer results */
|
|
verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
|
|
dst, bpf_alu_string[opcode >> 4]);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type))
|
|
return -EINVAL;
|
|
|
|
__update_reg_bounds(dst_reg);
|
|
__reg_deduce_bounds(dst_reg);
|
|
__reg_bound_offset(dst_reg);
|
|
|
|
/* For unprivileged we require that resulting offset must be in bounds
|
|
* in order to be able to sanitize access later on.
|
|
*/
|
|
if (!env->allow_ptr_leaks) {
|
|
if (dst_reg->type == PTR_TO_MAP_VALUE &&
|
|
check_map_access(env, dst, dst_reg->off, 1, false)) {
|
|
verbose(env, "R%d pointer arithmetic of map value goes out of range, "
|
|
"prohibited for !root\n", dst);
|
|
return -EACCES;
|
|
} else if (dst_reg->type == PTR_TO_STACK &&
|
|
check_stack_access(env, dst_reg, dst_reg->off +
|
|
dst_reg->var_off.value, 1)) {
|
|
verbose(env, "R%d stack pointer arithmetic goes out of range, "
|
|
"prohibited for !root\n", dst);
|
|
return -EACCES;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* WARNING: This function does calculations on 64-bit values, but the actual
|
|
* execution may occur on 32-bit values. Therefore, things like bitshifts
|
|
* need extra checks in the 32-bit case.
|
|
*/
|
|
static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn,
|
|
struct bpf_reg_state *dst_reg,
|
|
struct bpf_reg_state src_reg)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env);
|
|
u8 opcode = BPF_OP(insn->code);
|
|
bool src_known, dst_known;
|
|
s64 smin_val, smax_val;
|
|
u64 umin_val, umax_val;
|
|
u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
|
|
u32 dst = insn->dst_reg;
|
|
int ret;
|
|
|
|
if (insn_bitness == 32) {
|
|
/* Relevant for 32-bit RSH: Information can propagate towards
|
|
* LSB, so it isn't sufficient to only truncate the output to
|
|
* 32 bits.
|
|
*/
|
|
coerce_reg_to_size(dst_reg, 4);
|
|
coerce_reg_to_size(&src_reg, 4);
|
|
}
|
|
|
|
smin_val = src_reg.smin_value;
|
|
smax_val = src_reg.smax_value;
|
|
umin_val = src_reg.umin_value;
|
|
umax_val = src_reg.umax_value;
|
|
src_known = tnum_is_const(src_reg.var_off);
|
|
dst_known = tnum_is_const(dst_reg->var_off);
|
|
|
|
if ((src_known && (smin_val != smax_val || umin_val != umax_val)) ||
|
|
smin_val > smax_val || umin_val > umax_val) {
|
|
/* Taint dst register if offset had invalid bounds derived from
|
|
* e.g. dead branches.
|
|
*/
|
|
__mark_reg_unknown(dst_reg);
|
|
return 0;
|
|
}
|
|
|
|
if (!src_known &&
|
|
opcode != BPF_ADD && opcode != BPF_SUB && opcode != BPF_AND) {
|
|
__mark_reg_unknown(dst_reg);
|
|
return 0;
|
|
}
|
|
|
|
switch (opcode) {
|
|
case BPF_ADD:
|
|
ret = sanitize_val_alu(env, insn);
|
|
if (ret < 0) {
|
|
verbose(env, "R%d tried to add from different pointers or scalars\n", dst);
|
|
return ret;
|
|
}
|
|
if (signed_add_overflows(dst_reg->smin_value, smin_val) ||
|
|
signed_add_overflows(dst_reg->smax_value, smax_val)) {
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
} else {
|
|
dst_reg->smin_value += smin_val;
|
|
dst_reg->smax_value += smax_val;
|
|
}
|
|
if (dst_reg->umin_value + umin_val < umin_val ||
|
|
dst_reg->umax_value + umax_val < umax_val) {
|
|
dst_reg->umin_value = 0;
|
|
dst_reg->umax_value = U64_MAX;
|
|
} else {
|
|
dst_reg->umin_value += umin_val;
|
|
dst_reg->umax_value += umax_val;
|
|
}
|
|
dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
|
|
break;
|
|
case BPF_SUB:
|
|
ret = sanitize_val_alu(env, insn);
|
|
if (ret < 0) {
|
|
verbose(env, "R%d tried to sub from different pointers or scalars\n", dst);
|
|
return ret;
|
|
}
|
|
if (signed_sub_overflows(dst_reg->smin_value, smax_val) ||
|
|
signed_sub_overflows(dst_reg->smax_value, smin_val)) {
|
|
/* Overflow possible, we know nothing */
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
} else {
|
|
dst_reg->smin_value -= smax_val;
|
|
dst_reg->smax_value -= smin_val;
|
|
}
|
|
if (dst_reg->umin_value < umax_val) {
|
|
/* Overflow possible, we know nothing */
|
|
dst_reg->umin_value = 0;
|
|
dst_reg->umax_value = U64_MAX;
|
|
} else {
|
|
/* Cannot overflow (as long as bounds are consistent) */
|
|
dst_reg->umin_value -= umax_val;
|
|
dst_reg->umax_value -= umin_val;
|
|
}
|
|
dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
|
|
break;
|
|
case BPF_MUL:
|
|
dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
|
|
if (smin_val < 0 || dst_reg->smin_value < 0) {
|
|
/* Ain't nobody got time to multiply that sign */
|
|
__mark_reg_unbounded(dst_reg);
|
|
__update_reg_bounds(dst_reg);
|
|
break;
|
|
}
|
|
/* Both values are positive, so we can work with unsigned and
|
|
* copy the result to signed (unless it exceeds S64_MAX).
|
|
*/
|
|
if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
|
|
/* Potential overflow, we know nothing */
|
|
__mark_reg_unbounded(dst_reg);
|
|
/* (except what we can learn from the var_off) */
|
|
__update_reg_bounds(dst_reg);
|
|
break;
|
|
}
|
|
dst_reg->umin_value *= umin_val;
|
|
dst_reg->umax_value *= umax_val;
|
|
if (dst_reg->umax_value > S64_MAX) {
|
|
/* Overflow possible, we know nothing */
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
} else {
|
|
dst_reg->smin_value = dst_reg->umin_value;
|
|
dst_reg->smax_value = dst_reg->umax_value;
|
|
}
|
|
break;
|
|
case BPF_AND:
|
|
if (src_known && dst_known) {
|
|
__mark_reg_known(dst_reg, dst_reg->var_off.value &
|
|
src_reg.var_off.value);
|
|
break;
|
|
}
|
|
/* We get our minimum from the var_off, since that's inherently
|
|
* bitwise. Our maximum is the minimum of the operands' maxima.
|
|
*/
|
|
dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
|
|
dst_reg->umin_value = dst_reg->var_off.value;
|
|
dst_reg->umax_value = min(dst_reg->umax_value, umax_val);
|
|
if (dst_reg->smin_value < 0 || smin_val < 0) {
|
|
/* Lose signed bounds when ANDing negative numbers,
|
|
* ain't nobody got time for that.
|
|
*/
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
} else {
|
|
/* ANDing two positives gives a positive, so safe to
|
|
* cast result into s64.
|
|
*/
|
|
dst_reg->smin_value = dst_reg->umin_value;
|
|
dst_reg->smax_value = dst_reg->umax_value;
|
|
}
|
|
/* We may learn something more from the var_off */
|
|
__update_reg_bounds(dst_reg);
|
|
break;
|
|
case BPF_OR:
|
|
if (src_known && dst_known) {
|
|
__mark_reg_known(dst_reg, dst_reg->var_off.value |
|
|
src_reg.var_off.value);
|
|
break;
|
|
}
|
|
/* We get our maximum from the var_off, and our minimum is the
|
|
* maximum of the operands' minima
|
|
*/
|
|
dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
|
|
dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
|
|
dst_reg->umax_value = dst_reg->var_off.value |
|
|
dst_reg->var_off.mask;
|
|
if (dst_reg->smin_value < 0 || smin_val < 0) {
|
|
/* Lose signed bounds when ORing negative numbers,
|
|
* ain't nobody got time for that.
|
|
*/
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
} else {
|
|
/* ORing two positives gives a positive, so safe to
|
|
* cast result into s64.
|
|
*/
|
|
dst_reg->smin_value = dst_reg->umin_value;
|
|
dst_reg->smax_value = dst_reg->umax_value;
|
|
}
|
|
/* We may learn something more from the var_off */
|
|
__update_reg_bounds(dst_reg);
|
|
break;
|
|
case BPF_LSH:
|
|
if (umax_val >= insn_bitness) {
|
|
/* Shifts greater than 31 or 63 are undefined.
|
|
* This includes shifts by a negative number.
|
|
*/
|
|
mark_reg_unknown(env, regs, insn->dst_reg);
|
|
break;
|
|
}
|
|
/* We lose all sign bit information (except what we can pick
|
|
* up from var_off)
|
|
*/
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
/* If we might shift our top bit out, then we know nothing */
|
|
if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
|
|
dst_reg->umin_value = 0;
|
|
dst_reg->umax_value = U64_MAX;
|
|
} else {
|
|
dst_reg->umin_value <<= umin_val;
|
|
dst_reg->umax_value <<= umax_val;
|
|
}
|
|
dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
|
|
/* We may learn something more from the var_off */
|
|
__update_reg_bounds(dst_reg);
|
|
break;
|
|
case BPF_RSH:
|
|
if (umax_val >= insn_bitness) {
|
|
/* Shifts greater than 31 or 63 are undefined.
|
|
* This includes shifts by a negative number.
|
|
*/
|
|
mark_reg_unknown(env, regs, insn->dst_reg);
|
|
break;
|
|
}
|
|
/* BPF_RSH is an unsigned shift. If the value in dst_reg might
|
|
* be negative, then either:
|
|
* 1) src_reg might be zero, so the sign bit of the result is
|
|
* unknown, so we lose our signed bounds
|
|
* 2) it's known negative, thus the unsigned bounds capture the
|
|
* signed bounds
|
|
* 3) the signed bounds cross zero, so they tell us nothing
|
|
* about the result
|
|
* If the value in dst_reg is known nonnegative, then again the
|
|
* unsigned bounts capture the signed bounds.
|
|
* Thus, in all cases it suffices to blow away our signed bounds
|
|
* and rely on inferring new ones from the unsigned bounds and
|
|
* var_off of the result.
|
|
*/
|
|
dst_reg->smin_value = S64_MIN;
|
|
dst_reg->smax_value = S64_MAX;
|
|
dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
|
|
dst_reg->umin_value >>= umax_val;
|
|
dst_reg->umax_value >>= umin_val;
|
|
/* We may learn something more from the var_off */
|
|
__update_reg_bounds(dst_reg);
|
|
break;
|
|
case BPF_ARSH:
|
|
if (umax_val >= insn_bitness) {
|
|
/* Shifts greater than 31 or 63 are undefined.
|
|
* This includes shifts by a negative number.
|
|
*/
|
|
mark_reg_unknown(env, regs, insn->dst_reg);
|
|
break;
|
|
}
|
|
|
|
/* Upon reaching here, src_known is true and
|
|
* umax_val is equal to umin_val.
|
|
*/
|
|
if (insn_bitness == 32) {
|
|
dst_reg->smin_value = (u32)(((s32)dst_reg->smin_value) >> umin_val);
|
|
dst_reg->smax_value = (u32)(((s32)dst_reg->smax_value) >> umin_val);
|
|
} else {
|
|
dst_reg->smin_value >>= umin_val;
|
|
dst_reg->smax_value >>= umin_val;
|
|
}
|
|
|
|
dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val,
|
|
insn_bitness);
|
|
|
|
/* blow away the dst_reg umin_value/umax_value and rely on
|
|
* dst_reg var_off to refine the result.
|
|
*/
|
|
dst_reg->umin_value = 0;
|
|
dst_reg->umax_value = U64_MAX;
|
|
__update_reg_bounds(dst_reg);
|
|
break;
|
|
default:
|
|
mark_reg_unknown(env, regs, insn->dst_reg);
|
|
break;
|
|
}
|
|
|
|
if (BPF_CLASS(insn->code) != BPF_ALU64) {
|
|
/* 32-bit ALU ops are (32,32)->32 */
|
|
coerce_reg_to_size(dst_reg, 4);
|
|
}
|
|
|
|
__reg_deduce_bounds(dst_reg);
|
|
__reg_bound_offset(dst_reg);
|
|
return 0;
|
|
}
|
|
|
|
/* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
|
|
* and var_off.
|
|
*/
|
|
static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn)
|
|
{
|
|
struct bpf_verifier_state *vstate = env->cur_state;
|
|
struct bpf_func_state *state = vstate->frame[vstate->curframe];
|
|
struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
|
|
struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
|
|
u8 opcode = BPF_OP(insn->code);
|
|
|
|
dst_reg = ®s[insn->dst_reg];
|
|
src_reg = NULL;
|
|
if (dst_reg->type != SCALAR_VALUE)
|
|
ptr_reg = dst_reg;
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
src_reg = ®s[insn->src_reg];
|
|
if (src_reg->type != SCALAR_VALUE) {
|
|
if (dst_reg->type != SCALAR_VALUE) {
|
|
/* Combining two pointers by any ALU op yields
|
|
* an arbitrary scalar. Disallow all math except
|
|
* pointer subtraction
|
|
*/
|
|
if (opcode == BPF_SUB && env->allow_ptr_leaks) {
|
|
mark_reg_unknown(env, regs, insn->dst_reg);
|
|
return 0;
|
|
}
|
|
verbose(env, "R%d pointer %s pointer prohibited\n",
|
|
insn->dst_reg,
|
|
bpf_alu_string[opcode >> 4]);
|
|
return -EACCES;
|
|
} else {
|
|
/* scalar += pointer
|
|
* This is legal, but we have to reverse our
|
|
* src/dest handling in computing the range
|
|
*/
|
|
return adjust_ptr_min_max_vals(env, insn,
|
|
src_reg, dst_reg);
|
|
}
|
|
} else if (ptr_reg) {
|
|
/* pointer += scalar */
|
|
return adjust_ptr_min_max_vals(env, insn,
|
|
dst_reg, src_reg);
|
|
}
|
|
} else {
|
|
/* Pretend the src is a reg with a known value, since we only
|
|
* need to be able to read from this state.
|
|
*/
|
|
off_reg.type = SCALAR_VALUE;
|
|
__mark_reg_known(&off_reg, insn->imm);
|
|
src_reg = &off_reg;
|
|
if (ptr_reg) /* pointer += K */
|
|
return adjust_ptr_min_max_vals(env, insn,
|
|
ptr_reg, src_reg);
|
|
}
|
|
|
|
/* Got here implies adding two SCALAR_VALUEs */
|
|
if (WARN_ON_ONCE(ptr_reg)) {
|
|
print_verifier_state(env, state);
|
|
verbose(env, "verifier internal error: unexpected ptr_reg\n");
|
|
return -EINVAL;
|
|
}
|
|
if (WARN_ON(!src_reg)) {
|
|
print_verifier_state(env, state);
|
|
verbose(env, "verifier internal error: no src_reg\n");
|
|
return -EINVAL;
|
|
}
|
|
return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
|
|
}
|
|
|
|
/* check validity of 32-bit and 64-bit arithmetic operations */
|
|
static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env);
|
|
u8 opcode = BPF_OP(insn->code);
|
|
int err;
|
|
|
|
if (opcode == BPF_END || opcode == BPF_NEG) {
|
|
if (opcode == BPF_NEG) {
|
|
if (BPF_SRC(insn->code) != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->off != 0 || insn->imm != 0) {
|
|
verbose(env, "BPF_NEG uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
|
|
(insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
|
|
BPF_CLASS(insn->code) == BPF_ALU64) {
|
|
verbose(env, "BPF_END uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_pointer_value(env, insn->dst_reg)) {
|
|
verbose(env, "R%d pointer arithmetic prohibited\n",
|
|
insn->dst_reg);
|
|
return -EACCES;
|
|
}
|
|
|
|
/* check dest operand */
|
|
err = check_reg_arg(env, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (opcode == BPF_MOV) {
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0 || insn->off != 0) {
|
|
verbose(env, "BPF_MOV uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(env, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
|
|
verbose(env, "BPF_MOV uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check dest operand, mark as required later */
|
|
err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
|
|
if (err)
|
|
return err;
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
struct bpf_reg_state *src_reg = regs + insn->src_reg;
|
|
struct bpf_reg_state *dst_reg = regs + insn->dst_reg;
|
|
|
|
if (BPF_CLASS(insn->code) == BPF_ALU64) {
|
|
/* case: R1 = R2
|
|
* copy register state to dest reg
|
|
*/
|
|
*dst_reg = *src_reg;
|
|
dst_reg->live |= REG_LIVE_WRITTEN;
|
|
} else {
|
|
/* R1 = (u32) R2 */
|
|
if (is_pointer_value(env, insn->src_reg)) {
|
|
verbose(env,
|
|
"R%d partial copy of pointer\n",
|
|
insn->src_reg);
|
|
return -EACCES;
|
|
} else if (src_reg->type == SCALAR_VALUE) {
|
|
*dst_reg = *src_reg;
|
|
dst_reg->live |= REG_LIVE_WRITTEN;
|
|
} else {
|
|
mark_reg_unknown(env, regs,
|
|
insn->dst_reg);
|
|
}
|
|
coerce_reg_to_size(dst_reg, 4);
|
|
}
|
|
} else {
|
|
/* case: R = imm
|
|
* remember the value we stored into this reg
|
|
*/
|
|
/* clear any state __mark_reg_known doesn't set */
|
|
mark_reg_unknown(env, regs, insn->dst_reg);
|
|
regs[insn->dst_reg].type = SCALAR_VALUE;
|
|
if (BPF_CLASS(insn->code) == BPF_ALU64) {
|
|
__mark_reg_known(regs + insn->dst_reg,
|
|
insn->imm);
|
|
} else {
|
|
__mark_reg_known(regs + insn->dst_reg,
|
|
(u32)insn->imm);
|
|
}
|
|
}
|
|
|
|
} else if (opcode > BPF_END) {
|
|
verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
|
|
return -EINVAL;
|
|
|
|
} else { /* all other ALU ops: and, sub, xor, add, ... */
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0 || insn->off != 0) {
|
|
verbose(env, "BPF_ALU uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
/* check src1 operand */
|
|
err = check_reg_arg(env, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
|
|
verbose(env, "BPF_ALU uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
|
|
BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
|
|
verbose(env, "div by zero\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (opcode == BPF_ARSH && BPF_CLASS(insn->code) != BPF_ALU64) {
|
|
verbose(env, "BPF_ARSH not supported for 32 bit ALU\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if ((opcode == BPF_LSH || opcode == BPF_RSH ||
|
|
opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
|
|
int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
|
|
|
|
if (insn->imm < 0 || insn->imm >= size) {
|
|
verbose(env, "invalid shift %d\n", insn->imm);
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check dest operand */
|
|
err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
|
|
if (err)
|
|
return err;
|
|
|
|
return adjust_reg_min_max_vals(env, insn);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
|
|
struct bpf_reg_state *dst_reg,
|
|
enum bpf_reg_type type,
|
|
bool range_right_open)
|
|
{
|
|
struct bpf_func_state *state = vstate->frame[vstate->curframe];
|
|
struct bpf_reg_state *regs = state->regs, *reg;
|
|
u16 new_range;
|
|
int i, j;
|
|
|
|
if (dst_reg->off < 0 ||
|
|
(dst_reg->off == 0 && range_right_open))
|
|
/* This doesn't give us any range */
|
|
return;
|
|
|
|
if (dst_reg->umax_value > MAX_PACKET_OFF ||
|
|
dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF)
|
|
/* Risk of overflow. For instance, ptr + (1<<63) may be less
|
|
* than pkt_end, but that's because it's also less than pkt.
|
|
*/
|
|
return;
|
|
|
|
new_range = dst_reg->off;
|
|
if (range_right_open)
|
|
new_range--;
|
|
|
|
/* Examples for register markings:
|
|
*
|
|
* pkt_data in dst register:
|
|
*
|
|
* r2 = r3;
|
|
* r2 += 8;
|
|
* if (r2 > pkt_end) goto <handle exception>
|
|
* <access okay>
|
|
*
|
|
* r2 = r3;
|
|
* r2 += 8;
|
|
* if (r2 < pkt_end) goto <access okay>
|
|
* <handle exception>
|
|
*
|
|
* Where:
|
|
* r2 == dst_reg, pkt_end == src_reg
|
|
* r2=pkt(id=n,off=8,r=0)
|
|
* r3=pkt(id=n,off=0,r=0)
|
|
*
|
|
* pkt_data in src register:
|
|
*
|
|
* r2 = r3;
|
|
* r2 += 8;
|
|
* if (pkt_end >= r2) goto <access okay>
|
|
* <handle exception>
|
|
*
|
|
* r2 = r3;
|
|
* r2 += 8;
|
|
* if (pkt_end <= r2) goto <handle exception>
|
|
* <access okay>
|
|
*
|
|
* Where:
|
|
* pkt_end == dst_reg, r2 == src_reg
|
|
* r2=pkt(id=n,off=8,r=0)
|
|
* r3=pkt(id=n,off=0,r=0)
|
|
*
|
|
* Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
|
|
* or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
|
|
* and [r3, r3 + 8-1) respectively is safe to access depending on
|
|
* the check.
|
|
*/
|
|
|
|
/* If our ids match, then we must have the same max_value. And we
|
|
* don't care about the other reg's fixed offset, since if it's too big
|
|
* the range won't allow anything.
|
|
* dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
|
|
*/
|
|
for (i = 0; i < MAX_BPF_REG; i++)
|
|
if (regs[i].type == type && regs[i].id == dst_reg->id)
|
|
/* keep the maximum range already checked */
|
|
regs[i].range = max(regs[i].range, new_range);
|
|
|
|
for (j = 0; j <= vstate->curframe; j++) {
|
|
state = vstate->frame[j];
|
|
for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
|
|
if (state->stack[i].slot_type[0] != STACK_SPILL)
|
|
continue;
|
|
reg = &state->stack[i].spilled_ptr;
|
|
if (reg->type == type && reg->id == dst_reg->id)
|
|
reg->range = max(reg->range, new_range);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* compute branch direction of the expression "if (reg opcode val) goto target;"
|
|
* and return:
|
|
* 1 - branch will be taken and "goto target" will be executed
|
|
* 0 - branch will not be taken and fall-through to next insn
|
|
* -1 - unknown. Example: "if (reg < 5)" is unknown when register value range [0,10]
|
|
*/
|
|
static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode)
|
|
{
|
|
if (__is_pointer_value(false, reg))
|
|
return -1;
|
|
|
|
switch (opcode) {
|
|
case BPF_JEQ:
|
|
if (tnum_is_const(reg->var_off))
|
|
return !!tnum_equals_const(reg->var_off, val);
|
|
break;
|
|
case BPF_JNE:
|
|
if (tnum_is_const(reg->var_off))
|
|
return !tnum_equals_const(reg->var_off, val);
|
|
break;
|
|
case BPF_JGT:
|
|
if (reg->umin_value > val)
|
|
return 1;
|
|
else if (reg->umax_value <= val)
|
|
return 0;
|
|
break;
|
|
case BPF_JSGT:
|
|
if (reg->smin_value > (s64)val)
|
|
return 1;
|
|
else if (reg->smax_value < (s64)val)
|
|
return 0;
|
|
break;
|
|
case BPF_JLT:
|
|
if (reg->umax_value < val)
|
|
return 1;
|
|
else if (reg->umin_value >= val)
|
|
return 0;
|
|
break;
|
|
case BPF_JSLT:
|
|
if (reg->smax_value < (s64)val)
|
|
return 1;
|
|
else if (reg->smin_value >= (s64)val)
|
|
return 0;
|
|
break;
|
|
case BPF_JGE:
|
|
if (reg->umin_value >= val)
|
|
return 1;
|
|
else if (reg->umax_value < val)
|
|
return 0;
|
|
break;
|
|
case BPF_JSGE:
|
|
if (reg->smin_value >= (s64)val)
|
|
return 1;
|
|
else if (reg->smax_value < (s64)val)
|
|
return 0;
|
|
break;
|
|
case BPF_JLE:
|
|
if (reg->umax_value <= val)
|
|
return 1;
|
|
else if (reg->umin_value > val)
|
|
return 0;
|
|
break;
|
|
case BPF_JSLE:
|
|
if (reg->smax_value <= (s64)val)
|
|
return 1;
|
|
else if (reg->smin_value > (s64)val)
|
|
return 0;
|
|
break;
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
/* Adjusts the register min/max values in the case that the dst_reg is the
|
|
* variable register that we are working on, and src_reg is a constant or we're
|
|
* simply doing a BPF_K check.
|
|
* In JEQ/JNE cases we also adjust the var_off values.
|
|
*/
|
|
static void reg_set_min_max(struct bpf_reg_state *true_reg,
|
|
struct bpf_reg_state *false_reg, u64 val,
|
|
u8 opcode)
|
|
{
|
|
/* If the dst_reg is a pointer, we can't learn anything about its
|
|
* variable offset from the compare (unless src_reg were a pointer into
|
|
* the same object, but we don't bother with that.
|
|
* Since false_reg and true_reg have the same type by construction, we
|
|
* only need to check one of them for pointerness.
|
|
*/
|
|
if (__is_pointer_value(false, false_reg))
|
|
return;
|
|
|
|
switch (opcode) {
|
|
case BPF_JEQ:
|
|
/* If this is false then we know nothing Jon Snow, but if it is
|
|
* true then we know for sure.
|
|
*/
|
|
__mark_reg_known(true_reg, val);
|
|
break;
|
|
case BPF_JNE:
|
|
/* If this is true we know nothing Jon Snow, but if it is false
|
|
* we know the value for sure;
|
|
*/
|
|
__mark_reg_known(false_reg, val);
|
|
break;
|
|
case BPF_JGT:
|
|
false_reg->umax_value = min(false_reg->umax_value, val);
|
|
true_reg->umin_value = max(true_reg->umin_value, val + 1);
|
|
break;
|
|
case BPF_JSGT:
|
|
false_reg->smax_value = min_t(s64, false_reg->smax_value, val);
|
|
true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1);
|
|
break;
|
|
case BPF_JLT:
|
|
false_reg->umin_value = max(false_reg->umin_value, val);
|
|
true_reg->umax_value = min(true_reg->umax_value, val - 1);
|
|
break;
|
|
case BPF_JSLT:
|
|
false_reg->smin_value = max_t(s64, false_reg->smin_value, val);
|
|
true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1);
|
|
break;
|
|
case BPF_JGE:
|
|
false_reg->umax_value = min(false_reg->umax_value, val - 1);
|
|
true_reg->umin_value = max(true_reg->umin_value, val);
|
|
break;
|
|
case BPF_JSGE:
|
|
false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1);
|
|
true_reg->smin_value = max_t(s64, true_reg->smin_value, val);
|
|
break;
|
|
case BPF_JLE:
|
|
false_reg->umin_value = max(false_reg->umin_value, val + 1);
|
|
true_reg->umax_value = min(true_reg->umax_value, val);
|
|
break;
|
|
case BPF_JSLE:
|
|
false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1);
|
|
true_reg->smax_value = min_t(s64, true_reg->smax_value, val);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
__reg_deduce_bounds(false_reg);
|
|
__reg_deduce_bounds(true_reg);
|
|
/* We might have learned some bits from the bounds. */
|
|
__reg_bound_offset(false_reg);
|
|
__reg_bound_offset(true_reg);
|
|
/* Intersecting with the old var_off might have improved our bounds
|
|
* slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
|
|
* then new var_off is (0; 0x7f...fc) which improves our umax.
|
|
*/
|
|
__update_reg_bounds(false_reg);
|
|
__update_reg_bounds(true_reg);
|
|
}
|
|
|
|
/* Same as above, but for the case that dst_reg holds a constant and src_reg is
|
|
* the variable reg.
|
|
*/
|
|
static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
|
|
struct bpf_reg_state *false_reg, u64 val,
|
|
u8 opcode)
|
|
{
|
|
if (__is_pointer_value(false, false_reg))
|
|
return;
|
|
|
|
switch (opcode) {
|
|
case BPF_JEQ:
|
|
/* If this is false then we know nothing Jon Snow, but if it is
|
|
* true then we know for sure.
|
|
*/
|
|
__mark_reg_known(true_reg, val);
|
|
break;
|
|
case BPF_JNE:
|
|
/* If this is true we know nothing Jon Snow, but if it is false
|
|
* we know the value for sure;
|
|
*/
|
|
__mark_reg_known(false_reg, val);
|
|
break;
|
|
case BPF_JGT:
|
|
true_reg->umax_value = min(true_reg->umax_value, val - 1);
|
|
false_reg->umin_value = max(false_reg->umin_value, val);
|
|
break;
|
|
case BPF_JSGT:
|
|
true_reg->smax_value = min_t(s64, true_reg->smax_value, val - 1);
|
|
false_reg->smin_value = max_t(s64, false_reg->smin_value, val);
|
|
break;
|
|
case BPF_JLT:
|
|
true_reg->umin_value = max(true_reg->umin_value, val + 1);
|
|
false_reg->umax_value = min(false_reg->umax_value, val);
|
|
break;
|
|
case BPF_JSLT:
|
|
true_reg->smin_value = max_t(s64, true_reg->smin_value, val + 1);
|
|
false_reg->smax_value = min_t(s64, false_reg->smax_value, val);
|
|
break;
|
|
case BPF_JGE:
|
|
true_reg->umax_value = min(true_reg->umax_value, val);
|
|
false_reg->umin_value = max(false_reg->umin_value, val + 1);
|
|
break;
|
|
case BPF_JSGE:
|
|
true_reg->smax_value = min_t(s64, true_reg->smax_value, val);
|
|
false_reg->smin_value = max_t(s64, false_reg->smin_value, val + 1);
|
|
break;
|
|
case BPF_JLE:
|
|
true_reg->umin_value = max(true_reg->umin_value, val);
|
|
false_reg->umax_value = min(false_reg->umax_value, val - 1);
|
|
break;
|
|
case BPF_JSLE:
|
|
true_reg->smin_value = max_t(s64, true_reg->smin_value, val);
|
|
false_reg->smax_value = min_t(s64, false_reg->smax_value, val - 1);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
__reg_deduce_bounds(false_reg);
|
|
__reg_deduce_bounds(true_reg);
|
|
/* We might have learned some bits from the bounds. */
|
|
__reg_bound_offset(false_reg);
|
|
__reg_bound_offset(true_reg);
|
|
/* Intersecting with the old var_off might have improved our bounds
|
|
* slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
|
|
* then new var_off is (0; 0x7f...fc) which improves our umax.
|
|
*/
|
|
__update_reg_bounds(false_reg);
|
|
__update_reg_bounds(true_reg);
|
|
}
|
|
|
|
/* Regs are known to be equal, so intersect their min/max/var_off */
|
|
static void __reg_combine_min_max(struct bpf_reg_state *src_reg,
|
|
struct bpf_reg_state *dst_reg)
|
|
{
|
|
src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value,
|
|
dst_reg->umin_value);
|
|
src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value,
|
|
dst_reg->umax_value);
|
|
src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value,
|
|
dst_reg->smin_value);
|
|
src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value,
|
|
dst_reg->smax_value);
|
|
src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off,
|
|
dst_reg->var_off);
|
|
/* We might have learned new bounds from the var_off. */
|
|
__update_reg_bounds(src_reg);
|
|
__update_reg_bounds(dst_reg);
|
|
/* We might have learned something about the sign bit. */
|
|
__reg_deduce_bounds(src_reg);
|
|
__reg_deduce_bounds(dst_reg);
|
|
/* We might have learned some bits from the bounds. */
|
|
__reg_bound_offset(src_reg);
|
|
__reg_bound_offset(dst_reg);
|
|
/* Intersecting with the old var_off might have improved our bounds
|
|
* slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
|
|
* then new var_off is (0; 0x7f...fc) which improves our umax.
|
|
*/
|
|
__update_reg_bounds(src_reg);
|
|
__update_reg_bounds(dst_reg);
|
|
}
|
|
|
|
static void reg_combine_min_max(struct bpf_reg_state *true_src,
|
|
struct bpf_reg_state *true_dst,
|
|
struct bpf_reg_state *false_src,
|
|
struct bpf_reg_state *false_dst,
|
|
u8 opcode)
|
|
{
|
|
switch (opcode) {
|
|
case BPF_JEQ:
|
|
__reg_combine_min_max(true_src, true_dst);
|
|
break;
|
|
case BPF_JNE:
|
|
__reg_combine_min_max(false_src, false_dst);
|
|
break;
|
|
}
|
|
}
|
|
|
|
static void mark_map_reg(struct bpf_reg_state *regs, u32 regno, u32 id,
|
|
bool is_null)
|
|
{
|
|
struct bpf_reg_state *reg = ®s[regno];
|
|
|
|
if (reg->type == PTR_TO_MAP_VALUE_OR_NULL && reg->id == id) {
|
|
/* Old offset (both fixed and variable parts) should
|
|
* have been known-zero, because we don't allow pointer
|
|
* arithmetic on pointers that might be NULL.
|
|
*/
|
|
if (WARN_ON_ONCE(reg->smin_value || reg->smax_value ||
|
|
!tnum_equals_const(reg->var_off, 0) ||
|
|
reg->off)) {
|
|
__mark_reg_known_zero(reg);
|
|
reg->off = 0;
|
|
}
|
|
if (is_null) {
|
|
reg->type = SCALAR_VALUE;
|
|
} else if (reg->map_ptr->inner_map_meta) {
|
|
reg->type = CONST_PTR_TO_MAP;
|
|
reg->map_ptr = reg->map_ptr->inner_map_meta;
|
|
} else {
|
|
reg->type = PTR_TO_MAP_VALUE;
|
|
}
|
|
/* We don't need id from this point onwards anymore, thus we
|
|
* should better reset it, so that state pruning has chances
|
|
* to take effect.
|
|
*/
|
|
reg->id = 0;
|
|
}
|
|
}
|
|
|
|
/* The logic is similar to find_good_pkt_pointers(), both could eventually
|
|
* be folded together at some point.
|
|
*/
|
|
static void mark_map_regs(struct bpf_verifier_state *vstate, u32 regno,
|
|
bool is_null)
|
|
{
|
|
struct bpf_func_state *state = vstate->frame[vstate->curframe];
|
|
struct bpf_reg_state *regs = state->regs;
|
|
u32 id = regs[regno].id;
|
|
int i, j;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++)
|
|
mark_map_reg(regs, i, id, is_null);
|
|
|
|
for (j = 0; j <= vstate->curframe; j++) {
|
|
state = vstate->frame[j];
|
|
for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
|
|
if (state->stack[i].slot_type[0] != STACK_SPILL)
|
|
continue;
|
|
mark_map_reg(&state->stack[i].spilled_ptr, 0, id, is_null);
|
|
}
|
|
}
|
|
}
|
|
|
|
static bool try_match_pkt_pointers(const struct bpf_insn *insn,
|
|
struct bpf_reg_state *dst_reg,
|
|
struct bpf_reg_state *src_reg,
|
|
struct bpf_verifier_state *this_branch,
|
|
struct bpf_verifier_state *other_branch)
|
|
{
|
|
if (BPF_SRC(insn->code) != BPF_X)
|
|
return false;
|
|
|
|
switch (BPF_OP(insn->code)) {
|
|
case BPF_JGT:
|
|
if ((dst_reg->type == PTR_TO_PACKET &&
|
|
src_reg->type == PTR_TO_PACKET_END) ||
|
|
(dst_reg->type == PTR_TO_PACKET_META &&
|
|
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
|
|
/* pkt_data' > pkt_end, pkt_meta' > pkt_data */
|
|
find_good_pkt_pointers(this_branch, dst_reg,
|
|
dst_reg->type, false);
|
|
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
|
|
src_reg->type == PTR_TO_PACKET) ||
|
|
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
|
|
src_reg->type == PTR_TO_PACKET_META)) {
|
|
/* pkt_end > pkt_data', pkt_data > pkt_meta' */
|
|
find_good_pkt_pointers(other_branch, src_reg,
|
|
src_reg->type, true);
|
|
} else {
|
|
return false;
|
|
}
|
|
break;
|
|
case BPF_JLT:
|
|
if ((dst_reg->type == PTR_TO_PACKET &&
|
|
src_reg->type == PTR_TO_PACKET_END) ||
|
|
(dst_reg->type == PTR_TO_PACKET_META &&
|
|
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
|
|
/* pkt_data' < pkt_end, pkt_meta' < pkt_data */
|
|
find_good_pkt_pointers(other_branch, dst_reg,
|
|
dst_reg->type, true);
|
|
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
|
|
src_reg->type == PTR_TO_PACKET) ||
|
|
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
|
|
src_reg->type == PTR_TO_PACKET_META)) {
|
|
/* pkt_end < pkt_data', pkt_data > pkt_meta' */
|
|
find_good_pkt_pointers(this_branch, src_reg,
|
|
src_reg->type, false);
|
|
} else {
|
|
return false;
|
|
}
|
|
break;
|
|
case BPF_JGE:
|
|
if ((dst_reg->type == PTR_TO_PACKET &&
|
|
src_reg->type == PTR_TO_PACKET_END) ||
|
|
(dst_reg->type == PTR_TO_PACKET_META &&
|
|
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
|
|
/* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
|
|
find_good_pkt_pointers(this_branch, dst_reg,
|
|
dst_reg->type, true);
|
|
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
|
|
src_reg->type == PTR_TO_PACKET) ||
|
|
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
|
|
src_reg->type == PTR_TO_PACKET_META)) {
|
|
/* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
|
|
find_good_pkt_pointers(other_branch, src_reg,
|
|
src_reg->type, false);
|
|
} else {
|
|
return false;
|
|
}
|
|
break;
|
|
case BPF_JLE:
|
|
if ((dst_reg->type == PTR_TO_PACKET &&
|
|
src_reg->type == PTR_TO_PACKET_END) ||
|
|
(dst_reg->type == PTR_TO_PACKET_META &&
|
|
reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
|
|
/* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
|
|
find_good_pkt_pointers(other_branch, dst_reg,
|
|
dst_reg->type, false);
|
|
} else if ((dst_reg->type == PTR_TO_PACKET_END &&
|
|
src_reg->type == PTR_TO_PACKET) ||
|
|
(reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
|
|
src_reg->type == PTR_TO_PACKET_META)) {
|
|
/* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
|
|
find_good_pkt_pointers(this_branch, src_reg,
|
|
src_reg->type, true);
|
|
} else {
|
|
return false;
|
|
}
|
|
break;
|
|
default:
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static int check_cond_jmp_op(struct bpf_verifier_env *env,
|
|
struct bpf_insn *insn, int *insn_idx)
|
|
{
|
|
struct bpf_verifier_state *this_branch = env->cur_state;
|
|
struct bpf_verifier_state *other_branch;
|
|
struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
|
|
struct bpf_reg_state *dst_reg, *other_branch_regs;
|
|
u8 opcode = BPF_OP(insn->code);
|
|
int err;
|
|
|
|
if (opcode > BPF_JSLE) {
|
|
verbose(env, "invalid BPF_JMP opcode %x\n", opcode);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0) {
|
|
verbose(env, "BPF_JMP uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(env, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_pointer_value(env, insn->src_reg)) {
|
|
verbose(env, "R%d pointer comparison prohibited\n",
|
|
insn->src_reg);
|
|
return -EACCES;
|
|
}
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0) {
|
|
verbose(env, "BPF_JMP uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
dst_reg = ®s[insn->dst_reg];
|
|
|
|
if (BPF_SRC(insn->code) == BPF_K) {
|
|
int pred = is_branch_taken(dst_reg, insn->imm, opcode);
|
|
|
|
if (pred == 1) {
|
|
/* only follow the goto, ignore fall-through */
|
|
*insn_idx += insn->off;
|
|
return 0;
|
|
} else if (pred == 0) {
|
|
/* only follow fall-through branch, since
|
|
* that's where the program will go
|
|
*/
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx,
|
|
false);
|
|
if (!other_branch)
|
|
return -EFAULT;
|
|
other_branch_regs = other_branch->frame[other_branch->curframe]->regs;
|
|
|
|
/* detect if we are comparing against a constant value so we can adjust
|
|
* our min/max values for our dst register.
|
|
* this is only legit if both are scalars (or pointers to the same
|
|
* object, I suppose, but we don't support that right now), because
|
|
* otherwise the different base pointers mean the offsets aren't
|
|
* comparable.
|
|
*/
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (dst_reg->type == SCALAR_VALUE &&
|
|
regs[insn->src_reg].type == SCALAR_VALUE) {
|
|
if (tnum_is_const(regs[insn->src_reg].var_off))
|
|
reg_set_min_max(&other_branch_regs[insn->dst_reg],
|
|
dst_reg, regs[insn->src_reg].var_off.value,
|
|
opcode);
|
|
else if (tnum_is_const(dst_reg->var_off))
|
|
reg_set_min_max_inv(&other_branch_regs[insn->src_reg],
|
|
®s[insn->src_reg],
|
|
dst_reg->var_off.value, opcode);
|
|
else if (opcode == BPF_JEQ || opcode == BPF_JNE)
|
|
/* Comparing for equality, we can combine knowledge */
|
|
reg_combine_min_max(&other_branch_regs[insn->src_reg],
|
|
&other_branch_regs[insn->dst_reg],
|
|
®s[insn->src_reg],
|
|
®s[insn->dst_reg], opcode);
|
|
}
|
|
} else if (dst_reg->type == SCALAR_VALUE) {
|
|
reg_set_min_max(&other_branch_regs[insn->dst_reg],
|
|
dst_reg, insn->imm, opcode);
|
|
}
|
|
|
|
/* detect if R == 0 where R is returned from bpf_map_lookup_elem() */
|
|
if (BPF_SRC(insn->code) == BPF_K &&
|
|
insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
|
|
dst_reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
|
|
/* Mark all identical map registers in each branch as either
|
|
* safe or unknown depending R == 0 or R != 0 conditional.
|
|
*/
|
|
mark_map_regs(this_branch, insn->dst_reg, opcode == BPF_JNE);
|
|
mark_map_regs(other_branch, insn->dst_reg, opcode == BPF_JEQ);
|
|
} else if (!try_match_pkt_pointers(insn, dst_reg, ®s[insn->src_reg],
|
|
this_branch, other_branch) &&
|
|
is_pointer_value(env, insn->dst_reg)) {
|
|
verbose(env, "R%d pointer comparison prohibited\n",
|
|
insn->dst_reg);
|
|
return -EACCES;
|
|
}
|
|
if (env->log.level)
|
|
print_verifier_state(env, this_branch->frame[this_branch->curframe]);
|
|
return 0;
|
|
}
|
|
|
|
/* return the map pointer stored inside BPF_LD_IMM64 instruction */
|
|
static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
|
|
{
|
|
u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
|
|
|
|
return (struct bpf_map *) (unsigned long) imm64;
|
|
}
|
|
|
|
/* verify BPF_LD_IMM64 instruction */
|
|
static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env);
|
|
int err;
|
|
|
|
if (BPF_SIZE(insn->code) != BPF_DW) {
|
|
verbose(env, "invalid BPF_LD_IMM insn\n");
|
|
return -EINVAL;
|
|
}
|
|
if (insn->off != 0) {
|
|
verbose(env, "BPF_LD_IMM64 uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
err = check_reg_arg(env, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (insn->src_reg == 0) {
|
|
u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
|
|
|
|
regs[insn->dst_reg].type = SCALAR_VALUE;
|
|
__mark_reg_known(®s[insn->dst_reg], imm);
|
|
return 0;
|
|
}
|
|
|
|
/* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
|
|
BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
|
|
|
|
regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
|
|
regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
|
|
return 0;
|
|
}
|
|
|
|
static bool may_access_skb(enum bpf_prog_type type)
|
|
{
|
|
switch (type) {
|
|
case BPF_PROG_TYPE_SOCKET_FILTER:
|
|
case BPF_PROG_TYPE_SCHED_CLS:
|
|
case BPF_PROG_TYPE_SCHED_ACT:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* verify safety of LD_ABS|LD_IND instructions:
|
|
* - they can only appear in the programs where ctx == skb
|
|
* - since they are wrappers of function calls, they scratch R1-R5 registers,
|
|
* preserve R6-R9, and store return value into R0
|
|
*
|
|
* Implicit input:
|
|
* ctx == skb == R6 == CTX
|
|
*
|
|
* Explicit input:
|
|
* SRC == any register
|
|
* IMM == 32-bit immediate
|
|
*
|
|
* Output:
|
|
* R0 - 8/16/32-bit skb data converted to cpu endianness
|
|
*/
|
|
static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct bpf_reg_state *regs = cur_regs(env);
|
|
static const int ctx_reg = BPF_REG_6;
|
|
u8 mode = BPF_MODE(insn->code);
|
|
int i, err;
|
|
|
|
if (!may_access_skb(env->prog->type)) {
|
|
verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!env->ops->gen_ld_abs) {
|
|
verbose(env, "bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (env->subprog_cnt > 1) {
|
|
/* when program has LD_ABS insn JITs and interpreter assume
|
|
* that r1 == ctx == skb which is not the case for callees
|
|
* that can have arbitrary arguments. It's problematic
|
|
* for main prog as well since JITs would need to analyze
|
|
* all functions in order to make proper register save/restore
|
|
* decisions in the main prog. Hence disallow LD_ABS with calls
|
|
*/
|
|
verbose(env, "BPF_LD_[ABS|IND] instructions cannot be mixed with bpf-to-bpf calls\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
|
|
BPF_SIZE(insn->code) == BPF_DW ||
|
|
(mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
|
|
verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check whether implicit source operand (register R6) is readable */
|
|
err = check_reg_arg(env, ctx_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (regs[ctx_reg].type != PTR_TO_CTX) {
|
|
verbose(env,
|
|
"at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (mode == BPF_IND) {
|
|
/* check explicit source operand */
|
|
err = check_reg_arg(env, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
err = check_ctx_reg(env, ®s[ctx_reg], ctx_reg);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
/* reset caller saved regs to unreadable */
|
|
for (i = 0; i < CALLER_SAVED_REGS; i++) {
|
|
mark_reg_not_init(env, regs, caller_saved[i]);
|
|
check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
|
|
}
|
|
|
|
/* mark destination R0 register as readable, since it contains
|
|
* the value fetched from the packet.
|
|
* Already marked as written above.
|
|
*/
|
|
mark_reg_unknown(env, regs, BPF_REG_0);
|
|
return 0;
|
|
}
|
|
|
|
static int check_return_code(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_reg_state *reg;
|
|
struct tnum range = tnum_range(0, 1);
|
|
|
|
switch (env->prog->type) {
|
|
case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
|
|
if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
|
|
env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG)
|
|
range = tnum_range(1, 1);
|
|
case BPF_PROG_TYPE_CGROUP_SKB:
|
|
case BPF_PROG_TYPE_CGROUP_SOCK:
|
|
case BPF_PROG_TYPE_SOCK_OPS:
|
|
case BPF_PROG_TYPE_CGROUP_DEVICE:
|
|
break;
|
|
default:
|
|
return 0;
|
|
}
|
|
|
|
reg = cur_regs(env) + BPF_REG_0;
|
|
if (reg->type != SCALAR_VALUE) {
|
|
verbose(env, "At program exit the register R0 is not a known value (%s)\n",
|
|
reg_type_str[reg->type]);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!tnum_in(range, reg->var_off)) {
|
|
char tn_buf[48];
|
|
|
|
verbose(env, "At program exit the register R0 ");
|
|
if (!tnum_is_unknown(reg->var_off)) {
|
|
tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
|
|
verbose(env, "has value %s", tn_buf);
|
|
} else {
|
|
verbose(env, "has unknown scalar value");
|
|
}
|
|
tnum_strn(tn_buf, sizeof(tn_buf), range);
|
|
verbose(env, " should have been in %s\n", tn_buf);
|
|
return -EINVAL;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* non-recursive DFS pseudo code
|
|
* 1 procedure DFS-iterative(G,v):
|
|
* 2 label v as discovered
|
|
* 3 let S be a stack
|
|
* 4 S.push(v)
|
|
* 5 while S is not empty
|
|
* 6 t <- S.pop()
|
|
* 7 if t is what we're looking for:
|
|
* 8 return t
|
|
* 9 for all edges e in G.adjacentEdges(t) do
|
|
* 10 if edge e is already labelled
|
|
* 11 continue with the next edge
|
|
* 12 w <- G.adjacentVertex(t,e)
|
|
* 13 if vertex w is not discovered and not explored
|
|
* 14 label e as tree-edge
|
|
* 15 label w as discovered
|
|
* 16 S.push(w)
|
|
* 17 continue at 5
|
|
* 18 else if vertex w is discovered
|
|
* 19 label e as back-edge
|
|
* 20 else
|
|
* 21 // vertex w is explored
|
|
* 22 label e as forward- or cross-edge
|
|
* 23 label t as explored
|
|
* 24 S.pop()
|
|
*
|
|
* convention:
|
|
* 0x10 - discovered
|
|
* 0x11 - discovered and fall-through edge labelled
|
|
* 0x12 - discovered and fall-through and branch edges labelled
|
|
* 0x20 - explored
|
|
*/
|
|
|
|
enum {
|
|
DISCOVERED = 0x10,
|
|
EXPLORED = 0x20,
|
|
FALLTHROUGH = 1,
|
|
BRANCH = 2,
|
|
};
|
|
|
|
#define STATE_LIST_MARK ((struct bpf_verifier_state_list *) -1L)
|
|
|
|
static int *insn_stack; /* stack of insns to process */
|
|
static int cur_stack; /* current stack index */
|
|
static int *insn_state;
|
|
|
|
/* t, w, e - match pseudo-code above:
|
|
* t - index of current instruction
|
|
* w - next instruction
|
|
* e - edge
|
|
*/
|
|
static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
|
|
{
|
|
if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
|
|
return 0;
|
|
|
|
if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
|
|
return 0;
|
|
|
|
if (w < 0 || w >= env->prog->len) {
|
|
verbose(env, "jump out of range from insn %d to %d\n", t, w);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (e == BRANCH)
|
|
/* mark branch target for state pruning */
|
|
env->explored_states[w] = STATE_LIST_MARK;
|
|
|
|
if (insn_state[w] == 0) {
|
|
/* tree-edge */
|
|
insn_state[t] = DISCOVERED | e;
|
|
insn_state[w] = DISCOVERED;
|
|
if (cur_stack >= env->prog->len)
|
|
return -E2BIG;
|
|
insn_stack[cur_stack++] = w;
|
|
return 1;
|
|
} else if ((insn_state[w] & 0xF0) == DISCOVERED) {
|
|
verbose(env, "back-edge from insn %d to %d\n", t, w);
|
|
return -EINVAL;
|
|
} else if (insn_state[w] == EXPLORED) {
|
|
/* forward- or cross-edge */
|
|
insn_state[t] = DISCOVERED | e;
|
|
} else {
|
|
verbose(env, "insn state internal bug\n");
|
|
return -EFAULT;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* non-recursive depth-first-search to detect loops in BPF program
|
|
* loop == back-edge in directed graph
|
|
*/
|
|
static int check_cfg(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_insn *insns = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int ret = 0;
|
|
int i, t;
|
|
|
|
ret = check_subprogs(env);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
|
|
if (!insn_state)
|
|
return -ENOMEM;
|
|
|
|
insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
|
|
if (!insn_stack) {
|
|
kfree(insn_state);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
|
|
insn_stack[0] = 0; /* 0 is the first instruction */
|
|
cur_stack = 1;
|
|
|
|
peek_stack:
|
|
if (cur_stack == 0)
|
|
goto check_state;
|
|
t = insn_stack[cur_stack - 1];
|
|
|
|
if (BPF_CLASS(insns[t].code) == BPF_JMP) {
|
|
u8 opcode = BPF_OP(insns[t].code);
|
|
|
|
if (opcode == BPF_EXIT) {
|
|
goto mark_explored;
|
|
} else if (opcode == BPF_CALL) {
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
if (t + 1 < insn_cnt)
|
|
env->explored_states[t + 1] = STATE_LIST_MARK;
|
|
if (insns[t].src_reg == BPF_PSEUDO_CALL) {
|
|
env->explored_states[t] = STATE_LIST_MARK;
|
|
ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
}
|
|
} else if (opcode == BPF_JA) {
|
|
if (BPF_SRC(insns[t].code) != BPF_K) {
|
|
ret = -EINVAL;
|
|
goto err_free;
|
|
}
|
|
/* unconditional jump with single edge */
|
|
ret = push_insn(t, t + insns[t].off + 1,
|
|
FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
/* tell verifier to check for equivalent states
|
|
* after every call and jump
|
|
*/
|
|
if (t + 1 < insn_cnt)
|
|
env->explored_states[t + 1] = STATE_LIST_MARK;
|
|
} else {
|
|
/* conditional jump with two edges */
|
|
env->explored_states[t] = STATE_LIST_MARK;
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
|
|
ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
}
|
|
} else {
|
|
/* all other non-branch instructions with single
|
|
* fall-through edge
|
|
*/
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
}
|
|
|
|
mark_explored:
|
|
insn_state[t] = EXPLORED;
|
|
if (cur_stack-- <= 0) {
|
|
verbose(env, "pop stack internal bug\n");
|
|
ret = -EFAULT;
|
|
goto err_free;
|
|
}
|
|
goto peek_stack;
|
|
|
|
check_state:
|
|
for (i = 0; i < insn_cnt; i++) {
|
|
if (insn_state[i] != EXPLORED) {
|
|
verbose(env, "unreachable insn %d\n", i);
|
|
ret = -EINVAL;
|
|
goto err_free;
|
|
}
|
|
}
|
|
ret = 0; /* cfg looks good */
|
|
|
|
err_free:
|
|
kfree(insn_state);
|
|
kfree(insn_stack);
|
|
return ret;
|
|
}
|
|
|
|
/* check %cur's range satisfies %old's */
|
|
static bool range_within(struct bpf_reg_state *old,
|
|
struct bpf_reg_state *cur)
|
|
{
|
|
return old->umin_value <= cur->umin_value &&
|
|
old->umax_value >= cur->umax_value &&
|
|
old->smin_value <= cur->smin_value &&
|
|
old->smax_value >= cur->smax_value;
|
|
}
|
|
|
|
/* Maximum number of register states that can exist at once */
|
|
#define ID_MAP_SIZE (MAX_BPF_REG + MAX_BPF_STACK / BPF_REG_SIZE)
|
|
struct idpair {
|
|
u32 old;
|
|
u32 cur;
|
|
};
|
|
|
|
/* If in the old state two registers had the same id, then they need to have
|
|
* the same id in the new state as well. But that id could be different from
|
|
* the old state, so we need to track the mapping from old to new ids.
|
|
* Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
|
|
* regs with old id 5 must also have new id 9 for the new state to be safe. But
|
|
* regs with a different old id could still have new id 9, we don't care about
|
|
* that.
|
|
* So we look through our idmap to see if this old id has been seen before. If
|
|
* so, we require the new id to match; otherwise, we add the id pair to the map.
|
|
*/
|
|
static bool check_ids(u32 old_id, u32 cur_id, struct idpair *idmap)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < ID_MAP_SIZE; i++) {
|
|
if (!idmap[i].old) {
|
|
/* Reached an empty slot; haven't seen this id before */
|
|
idmap[i].old = old_id;
|
|
idmap[i].cur = cur_id;
|
|
return true;
|
|
}
|
|
if (idmap[i].old == old_id)
|
|
return idmap[i].cur == cur_id;
|
|
}
|
|
/* We ran out of idmap slots, which should be impossible */
|
|
WARN_ON_ONCE(1);
|
|
return false;
|
|
}
|
|
|
|
/* Returns true if (rold safe implies rcur safe) */
|
|
static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
|
|
struct idpair *idmap)
|
|
{
|
|
bool equal;
|
|
|
|
if (!(rold->live & REG_LIVE_READ))
|
|
/* explored state didn't use this */
|
|
return true;
|
|
|
|
equal = memcmp(rold, rcur, offsetof(struct bpf_reg_state, frameno)) == 0;
|
|
|
|
if (rold->type == PTR_TO_STACK)
|
|
/* two stack pointers are equal only if they're pointing to
|
|
* the same stack frame, since fp-8 in foo != fp-8 in bar
|
|
*/
|
|
return equal && rold->frameno == rcur->frameno;
|
|
|
|
if (equal)
|
|
return true;
|
|
|
|
if (rold->type == NOT_INIT)
|
|
/* explored state can't have used this */
|
|
return true;
|
|
if (rcur->type == NOT_INIT)
|
|
return false;
|
|
switch (rold->type) {
|
|
case SCALAR_VALUE:
|
|
if (rcur->type == SCALAR_VALUE) {
|
|
/* new val must satisfy old val knowledge */
|
|
return range_within(rold, rcur) &&
|
|
tnum_in(rold->var_off, rcur->var_off);
|
|
} else {
|
|
/* We're trying to use a pointer in place of a scalar.
|
|
* Even if the scalar was unbounded, this could lead to
|
|
* pointer leaks because scalars are allowed to leak
|
|
* while pointers are not. We could make this safe in
|
|
* special cases if root is calling us, but it's
|
|
* probably not worth the hassle.
|
|
*/
|
|
return false;
|
|
}
|
|
case PTR_TO_MAP_VALUE:
|
|
/* If the new min/max/var_off satisfy the old ones and
|
|
* everything else matches, we are OK.
|
|
* We don't care about the 'id' value, because nothing
|
|
* uses it for PTR_TO_MAP_VALUE (only for ..._OR_NULL)
|
|
*/
|
|
return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
|
|
range_within(rold, rcur) &&
|
|
tnum_in(rold->var_off, rcur->var_off);
|
|
case PTR_TO_MAP_VALUE_OR_NULL:
|
|
/* a PTR_TO_MAP_VALUE could be safe to use as a
|
|
* PTR_TO_MAP_VALUE_OR_NULL into the same map.
|
|
* However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
|
|
* checked, doing so could have affected others with the same
|
|
* id, and we can't check for that because we lost the id when
|
|
* we converted to a PTR_TO_MAP_VALUE.
|
|
*/
|
|
if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL)
|
|
return false;
|
|
if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)))
|
|
return false;
|
|
/* Check our ids match any regs they're supposed to */
|
|
return check_ids(rold->id, rcur->id, idmap);
|
|
case PTR_TO_PACKET_META:
|
|
case PTR_TO_PACKET:
|
|
if (rcur->type != rold->type)
|
|
return false;
|
|
/* We must have at least as much range as the old ptr
|
|
* did, so that any accesses which were safe before are
|
|
* still safe. This is true even if old range < old off,
|
|
* since someone could have accessed through (ptr - k), or
|
|
* even done ptr -= k in a register, to get a safe access.
|
|
*/
|
|
if (rold->range > rcur->range)
|
|
return false;
|
|
/* If the offsets don't match, we can't trust our alignment;
|
|
* nor can we be sure that we won't fall out of range.
|
|
*/
|
|
if (rold->off != rcur->off)
|
|
return false;
|
|
/* id relations must be preserved */
|
|
if (rold->id && !check_ids(rold->id, rcur->id, idmap))
|
|
return false;
|
|
/* new val must satisfy old val knowledge */
|
|
return range_within(rold, rcur) &&
|
|
tnum_in(rold->var_off, rcur->var_off);
|
|
case PTR_TO_CTX:
|
|
case CONST_PTR_TO_MAP:
|
|
case PTR_TO_PACKET_END:
|
|
/* Only valid matches are exact, which memcmp() above
|
|
* would have accepted
|
|
*/
|
|
default:
|
|
/* Don't know what's going on, just say it's not safe */
|
|
return false;
|
|
}
|
|
|
|
/* Shouldn't get here; if we do, say it's not safe */
|
|
WARN_ON_ONCE(1);
|
|
return false;
|
|
}
|
|
|
|
static bool stacksafe(struct bpf_func_state *old,
|
|
struct bpf_func_state *cur,
|
|
struct idpair *idmap)
|
|
{
|
|
int i, spi;
|
|
|
|
/* if explored stack has more populated slots than current stack
|
|
* such stacks are not equivalent
|
|
*/
|
|
if (old->allocated_stack > cur->allocated_stack)
|
|
return false;
|
|
|
|
/* walk slots of the explored stack and ignore any additional
|
|
* slots in the current stack, since explored(safe) state
|
|
* didn't use them
|
|
*/
|
|
for (i = 0; i < old->allocated_stack; i++) {
|
|
spi = i / BPF_REG_SIZE;
|
|
|
|
if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ))
|
|
/* explored state didn't use this */
|
|
continue;
|
|
|
|
if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID)
|
|
continue;
|
|
/* if old state was safe with misc data in the stack
|
|
* it will be safe with zero-initialized stack.
|
|
* The opposite is not true
|
|
*/
|
|
if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC &&
|
|
cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO)
|
|
continue;
|
|
if (old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
|
|
cur->stack[spi].slot_type[i % BPF_REG_SIZE])
|
|
/* Ex: old explored (safe) state has STACK_SPILL in
|
|
* this stack slot, but current has has STACK_MISC ->
|
|
* this verifier states are not equivalent,
|
|
* return false to continue verification of this path
|
|
*/
|
|
return false;
|
|
if (i % BPF_REG_SIZE)
|
|
continue;
|
|
if (old->stack[spi].slot_type[0] != STACK_SPILL)
|
|
continue;
|
|
if (!regsafe(&old->stack[spi].spilled_ptr,
|
|
&cur->stack[spi].spilled_ptr,
|
|
idmap))
|
|
/* when explored and current stack slot are both storing
|
|
* spilled registers, check that stored pointers types
|
|
* are the same as well.
|
|
* Ex: explored safe path could have stored
|
|
* (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
|
|
* but current path has stored:
|
|
* (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
|
|
* such verifier states are not equivalent.
|
|
* return false to continue verification of this path
|
|
*/
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/* compare two verifier states
|
|
*
|
|
* all states stored in state_list are known to be valid, since
|
|
* verifier reached 'bpf_exit' instruction through them
|
|
*
|
|
* this function is called when verifier exploring different branches of
|
|
* execution popped from the state stack. If it sees an old state that has
|
|
* more strict register state and more strict stack state then this execution
|
|
* branch doesn't need to be explored further, since verifier already
|
|
* concluded that more strict state leads to valid finish.
|
|
*
|
|
* Therefore two states are equivalent if register state is more conservative
|
|
* and explored stack state is more conservative than the current one.
|
|
* Example:
|
|
* explored current
|
|
* (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
|
|
* (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
|
|
*
|
|
* In other words if current stack state (one being explored) has more
|
|
* valid slots than old one that already passed validation, it means
|
|
* the verifier can stop exploring and conclude that current state is valid too
|
|
*
|
|
* Similarly with registers. If explored state has register type as invalid
|
|
* whereas register type in current state is meaningful, it means that
|
|
* the current state will reach 'bpf_exit' instruction safely
|
|
*/
|
|
static bool func_states_equal(struct bpf_func_state *old,
|
|
struct bpf_func_state *cur)
|
|
{
|
|
struct idpair *idmap;
|
|
bool ret = false;
|
|
int i;
|
|
|
|
idmap = kcalloc(ID_MAP_SIZE, sizeof(struct idpair), GFP_KERNEL);
|
|
/* If we failed to allocate the idmap, just say it's not safe */
|
|
if (!idmap)
|
|
return false;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++) {
|
|
if (!regsafe(&old->regs[i], &cur->regs[i], idmap))
|
|
goto out_free;
|
|
}
|
|
|
|
if (!stacksafe(old, cur, idmap))
|
|
goto out_free;
|
|
ret = true;
|
|
out_free:
|
|
kfree(idmap);
|
|
return ret;
|
|
}
|
|
|
|
static bool states_equal(struct bpf_verifier_env *env,
|
|
struct bpf_verifier_state *old,
|
|
struct bpf_verifier_state *cur)
|
|
{
|
|
int i;
|
|
|
|
if (old->curframe != cur->curframe)
|
|
return false;
|
|
|
|
/* Verification state from speculative execution simulation
|
|
* must never prune a non-speculative execution one.
|
|
*/
|
|
if (old->speculative && !cur->speculative)
|
|
return false;
|
|
|
|
/* for states to be equal callsites have to be the same
|
|
* and all frame states need to be equivalent
|
|
*/
|
|
for (i = 0; i <= old->curframe; i++) {
|
|
if (old->frame[i]->callsite != cur->frame[i]->callsite)
|
|
return false;
|
|
if (!func_states_equal(old->frame[i], cur->frame[i]))
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/* A write screens off any subsequent reads; but write marks come from the
|
|
* straight-line code between a state and its parent. When we arrive at an
|
|
* equivalent state (jump target or such) we didn't arrive by the straight-line
|
|
* code, so read marks in the state must propagate to the parent regardless
|
|
* of the state's write marks. That's what 'parent == state->parent' comparison
|
|
* in mark_reg_read() and mark_stack_slot_read() is for.
|
|
*/
|
|
static int propagate_liveness(struct bpf_verifier_env *env,
|
|
const struct bpf_verifier_state *vstate,
|
|
struct bpf_verifier_state *vparent)
|
|
{
|
|
int i, frame, err = 0;
|
|
struct bpf_func_state *state, *parent;
|
|
|
|
if (vparent->curframe != vstate->curframe) {
|
|
WARN(1, "propagate_live: parent frame %d current frame %d\n",
|
|
vparent->curframe, vstate->curframe);
|
|
return -EFAULT;
|
|
}
|
|
/* Propagate read liveness of registers... */
|
|
BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
|
|
/* We don't need to worry about FP liveness because it's read-only */
|
|
for (i = 0; i < BPF_REG_FP; i++) {
|
|
if (vparent->frame[vparent->curframe]->regs[i].live & REG_LIVE_READ)
|
|
continue;
|
|
if (vstate->frame[vstate->curframe]->regs[i].live & REG_LIVE_READ) {
|
|
err = mark_reg_read(env, vstate, vparent, i);
|
|
if (err)
|
|
return err;
|
|
}
|
|
}
|
|
|
|
/* ... and stack slots */
|
|
for (frame = 0; frame <= vstate->curframe; frame++) {
|
|
state = vstate->frame[frame];
|
|
parent = vparent->frame[frame];
|
|
for (i = 0; i < state->allocated_stack / BPF_REG_SIZE &&
|
|
i < parent->allocated_stack / BPF_REG_SIZE; i++) {
|
|
if (parent->stack[i].spilled_ptr.live & REG_LIVE_READ)
|
|
continue;
|
|
if (state->stack[i].spilled_ptr.live & REG_LIVE_READ)
|
|
mark_stack_slot_read(env, vstate, vparent, i, frame);
|
|
}
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
|
|
{
|
|
struct bpf_verifier_state_list *new_sl;
|
|
struct bpf_verifier_state_list *sl;
|
|
struct bpf_verifier_state *cur = env->cur_state;
|
|
int i, j, err, states_cnt = 0;
|
|
|
|
sl = env->explored_states[insn_idx];
|
|
if (!sl)
|
|
/* this 'insn_idx' instruction wasn't marked, so we will not
|
|
* be doing state search here
|
|
*/
|
|
return 0;
|
|
|
|
while (sl != STATE_LIST_MARK) {
|
|
if (states_equal(env, &sl->state, cur)) {
|
|
/* reached equivalent register/stack state,
|
|
* prune the search.
|
|
* Registers read by the continuation are read by us.
|
|
* If we have any write marks in env->cur_state, they
|
|
* will prevent corresponding reads in the continuation
|
|
* from reaching our parent (an explored_state). Our
|
|
* own state will get the read marks recorded, but
|
|
* they'll be immediately forgotten as we're pruning
|
|
* this state and will pop a new one.
|
|
*/
|
|
err = propagate_liveness(env, &sl->state, cur);
|
|
if (err)
|
|
return err;
|
|
return 1;
|
|
}
|
|
sl = sl->next;
|
|
states_cnt++;
|
|
}
|
|
|
|
if (!env->allow_ptr_leaks && states_cnt > BPF_COMPLEXITY_LIMIT_STATES)
|
|
return 0;
|
|
|
|
/* there were no equivalent states, remember current one.
|
|
* technically the current state is not proven to be safe yet,
|
|
* but it will either reach outer most bpf_exit (which means it's safe)
|
|
* or it will be rejected. Since there are no loops, we won't be
|
|
* seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx)
|
|
* again on the way to bpf_exit
|
|
*/
|
|
new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL);
|
|
if (!new_sl)
|
|
return -ENOMEM;
|
|
|
|
/* add new state to the head of linked list */
|
|
err = copy_verifier_state(&new_sl->state, cur);
|
|
if (err) {
|
|
free_verifier_state(&new_sl->state, false);
|
|
kfree(new_sl);
|
|
return err;
|
|
}
|
|
new_sl->next = env->explored_states[insn_idx];
|
|
env->explored_states[insn_idx] = new_sl;
|
|
/* connect new state to parentage chain */
|
|
cur->parent = &new_sl->state;
|
|
/* clear write marks in current state: the writes we did are not writes
|
|
* our child did, so they don't screen off its reads from us.
|
|
* (There are no read marks in current state, because reads always mark
|
|
* their parent and current state never has children yet. Only
|
|
* explored_states can get read marks.)
|
|
*/
|
|
for (i = 0; i < BPF_REG_FP; i++)
|
|
cur->frame[cur->curframe]->regs[i].live = REG_LIVE_NONE;
|
|
|
|
/* all stack frames are accessible from callee, clear them all */
|
|
for (j = 0; j <= cur->curframe; j++) {
|
|
struct bpf_func_state *frame = cur->frame[j];
|
|
|
|
for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++)
|
|
frame->stack[i].spilled_ptr.live = REG_LIVE_NONE;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int do_check(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_verifier_state *state;
|
|
struct bpf_insn *insns = env->prog->insnsi;
|
|
struct bpf_reg_state *regs;
|
|
int insn_cnt = env->prog->len, i;
|
|
int insn_processed = 0;
|
|
bool do_print_state = false;
|
|
|
|
state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
|
|
if (!state)
|
|
return -ENOMEM;
|
|
state->curframe = 0;
|
|
state->speculative = false;
|
|
state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL);
|
|
if (!state->frame[0]) {
|
|
kfree(state);
|
|
return -ENOMEM;
|
|
}
|
|
env->cur_state = state;
|
|
init_func_state(env, state->frame[0],
|
|
BPF_MAIN_FUNC /* callsite */,
|
|
0 /* frameno */,
|
|
0 /* subprogno, zero == main subprog */);
|
|
|
|
for (;;) {
|
|
struct bpf_insn *insn;
|
|
u8 class;
|
|
int err;
|
|
|
|
if (env->insn_idx >= insn_cnt) {
|
|
verbose(env, "invalid insn idx %d insn_cnt %d\n",
|
|
env->insn_idx, insn_cnt);
|
|
return -EFAULT;
|
|
}
|
|
|
|
insn = &insns[env->insn_idx];
|
|
class = BPF_CLASS(insn->code);
|
|
|
|
if (++insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
|
|
verbose(env,
|
|
"BPF program is too large. Processed %d insn\n",
|
|
insn_processed);
|
|
return -E2BIG;
|
|
}
|
|
|
|
err = is_state_visited(env, env->insn_idx);
|
|
if (err < 0)
|
|
return err;
|
|
if (err == 1) {
|
|
/* found equivalent state, can prune the search */
|
|
if (env->log.level) {
|
|
if (do_print_state)
|
|
verbose(env, "\nfrom %d to %d%s: safe\n",
|
|
env->prev_insn_idx, env->insn_idx,
|
|
env->cur_state->speculative ?
|
|
" (speculative execution)" : "");
|
|
else
|
|
verbose(env, "%d: safe\n", env->insn_idx);
|
|
}
|
|
goto process_bpf_exit;
|
|
}
|
|
|
|
if (signal_pending(current))
|
|
return -EAGAIN;
|
|
|
|
if (need_resched())
|
|
cond_resched();
|
|
|
|
if (env->log.level > 1 || (env->log.level && do_print_state)) {
|
|
if (env->log.level > 1)
|
|
verbose(env, "%d:", env->insn_idx);
|
|
else
|
|
verbose(env, "\nfrom %d to %d%s:",
|
|
env->prev_insn_idx, env->insn_idx,
|
|
env->cur_state->speculative ?
|
|
" (speculative execution)" : "");
|
|
print_verifier_state(env, state->frame[state->curframe]);
|
|
do_print_state = false;
|
|
}
|
|
|
|
if (env->log.level) {
|
|
const struct bpf_insn_cbs cbs = {
|
|
.cb_print = verbose,
|
|
.private_data = env,
|
|
};
|
|
|
|
verbose(env, "%d: ", env->insn_idx);
|
|
print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
|
|
}
|
|
|
|
if (bpf_prog_is_dev_bound(env->prog->aux)) {
|
|
err = bpf_prog_offload_verify_insn(env, env->insn_idx,
|
|
env->prev_insn_idx);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
regs = cur_regs(env);
|
|
env->insn_aux_data[env->insn_idx].seen = true;
|
|
|
|
if (class == BPF_ALU || class == BPF_ALU64) {
|
|
err = check_alu_op(env, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (class == BPF_LDX) {
|
|
enum bpf_reg_type *prev_src_type, src_reg_type;
|
|
|
|
/* check for reserved fields is already done */
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(env, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
|
|
if (err)
|
|
return err;
|
|
|
|
src_reg_type = regs[insn->src_reg].type;
|
|
|
|
/* check that memory (src_reg + off) is readable,
|
|
* the state of dst_reg will be updated by this func
|
|
*/
|
|
err = check_mem_access(env, env->insn_idx, insn->src_reg,
|
|
insn->off, BPF_SIZE(insn->code),
|
|
BPF_READ, insn->dst_reg, false);
|
|
if (err)
|
|
return err;
|
|
|
|
prev_src_type = &env->insn_aux_data[env->insn_idx].ptr_type;
|
|
|
|
if (*prev_src_type == NOT_INIT) {
|
|
/* saw a valid insn
|
|
* dst_reg = *(u32 *)(src_reg + off)
|
|
* save type to validate intersecting paths
|
|
*/
|
|
*prev_src_type = src_reg_type;
|
|
|
|
} else if (src_reg_type != *prev_src_type &&
|
|
(src_reg_type == PTR_TO_CTX ||
|
|
*prev_src_type == PTR_TO_CTX)) {
|
|
/* ABuser program is trying to use the same insn
|
|
* dst_reg = *(u32*) (src_reg + off)
|
|
* with different pointer types:
|
|
* src_reg == ctx in one branch and
|
|
* src_reg == stack|map in some other branch.
|
|
* Reject it.
|
|
*/
|
|
verbose(env, "same insn cannot be used with different pointers\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
} else if (class == BPF_STX) {
|
|
enum bpf_reg_type *prev_dst_type, dst_reg_type;
|
|
|
|
if (BPF_MODE(insn->code) == BPF_XADD) {
|
|
err = check_xadd(env, env->insn_idx, insn);
|
|
if (err)
|
|
return err;
|
|
env->insn_idx++;
|
|
continue;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(env, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
/* check src2 operand */
|
|
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
dst_reg_type = regs[insn->dst_reg].type;
|
|
|
|
/* check that memory (dst_reg + off) is writeable */
|
|
err = check_mem_access(env, env->insn_idx, insn->dst_reg,
|
|
insn->off, BPF_SIZE(insn->code),
|
|
BPF_WRITE, insn->src_reg, false);
|
|
if (err)
|
|
return err;
|
|
|
|
prev_dst_type = &env->insn_aux_data[env->insn_idx].ptr_type;
|
|
|
|
if (*prev_dst_type == NOT_INIT) {
|
|
*prev_dst_type = dst_reg_type;
|
|
} else if (dst_reg_type != *prev_dst_type &&
|
|
(dst_reg_type == PTR_TO_CTX ||
|
|
*prev_dst_type == PTR_TO_CTX)) {
|
|
verbose(env, "same insn cannot be used with different pointers\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
} else if (class == BPF_ST) {
|
|
if (BPF_MODE(insn->code) != BPF_MEM ||
|
|
insn->src_reg != BPF_REG_0) {
|
|
verbose(env, "BPF_ST uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
/* check src operand */
|
|
err = check_reg_arg(env, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_ctx_reg(env, insn->dst_reg)) {
|
|
verbose(env, "BPF_ST stores into R%d context is not allowed\n",
|
|
insn->dst_reg);
|
|
return -EACCES;
|
|
}
|
|
|
|
/* check that memory (dst_reg + off) is writeable */
|
|
err = check_mem_access(env, env->insn_idx, insn->dst_reg,
|
|
insn->off, BPF_SIZE(insn->code),
|
|
BPF_WRITE, -1, false);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (class == BPF_JMP) {
|
|
u8 opcode = BPF_OP(insn->code);
|
|
|
|
if (opcode == BPF_CALL) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->off != 0 ||
|
|
(insn->src_reg != BPF_REG_0 &&
|
|
insn->src_reg != BPF_PSEUDO_CALL) ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose(env, "BPF_CALL uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn->src_reg == BPF_PSEUDO_CALL)
|
|
err = check_func_call(env, insn, &env->insn_idx);
|
|
else
|
|
err = check_helper_call(env, insn->imm, env->insn_idx);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (opcode == BPF_JA) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->imm != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose(env, "BPF_JA uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
env->insn_idx += insn->off + 1;
|
|
continue;
|
|
|
|
} else if (opcode == BPF_EXIT) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->imm != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose(env, "BPF_EXIT uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (state->curframe) {
|
|
/* exit from nested function */
|
|
env->prev_insn_idx = env->insn_idx;
|
|
err = prepare_func_exit(env, &env->insn_idx);
|
|
if (err)
|
|
return err;
|
|
do_print_state = true;
|
|
continue;
|
|
}
|
|
|
|
/* eBPF calling convetion is such that R0 is used
|
|
* to return the value from eBPF program.
|
|
* Make sure that it's readable at this time
|
|
* of bpf_exit, which means that program wrote
|
|
* something into it earlier
|
|
*/
|
|
err = check_reg_arg(env, BPF_REG_0, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (is_pointer_value(env, BPF_REG_0)) {
|
|
verbose(env, "R0 leaks addr as return value\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
err = check_return_code(env);
|
|
if (err)
|
|
return err;
|
|
process_bpf_exit:
|
|
err = pop_stack(env, &env->prev_insn_idx,
|
|
&env->insn_idx);
|
|
if (err < 0) {
|
|
if (err != -ENOENT)
|
|
return err;
|
|
break;
|
|
} else {
|
|
do_print_state = true;
|
|
continue;
|
|
}
|
|
} else {
|
|
err = check_cond_jmp_op(env, insn, &env->insn_idx);
|
|
if (err)
|
|
return err;
|
|
}
|
|
} else if (class == BPF_LD) {
|
|
u8 mode = BPF_MODE(insn->code);
|
|
|
|
if (mode == BPF_ABS || mode == BPF_IND) {
|
|
err = check_ld_abs(env, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (mode == BPF_IMM) {
|
|
err = check_ld_imm(env, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
env->insn_idx++;
|
|
env->insn_aux_data[env->insn_idx].seen = true;
|
|
} else {
|
|
verbose(env, "invalid BPF_LD mode\n");
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
verbose(env, "unknown insn class %d\n", class);
|
|
return -EINVAL;
|
|
}
|
|
|
|
env->insn_idx++;
|
|
}
|
|
|
|
verbose(env, "processed %d insns (limit %d), stack depth ",
|
|
insn_processed, BPF_COMPLEXITY_LIMIT_INSNS);
|
|
for (i = 0; i < env->subprog_cnt; i++) {
|
|
u32 depth = env->subprog_info[i].stack_depth;
|
|
|
|
verbose(env, "%d", depth);
|
|
if (i + 1 < env->subprog_cnt)
|
|
verbose(env, "+");
|
|
}
|
|
verbose(env, "\n");
|
|
env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
|
|
return 0;
|
|
}
|
|
|
|
static int check_map_prealloc(struct bpf_map *map)
|
|
{
|
|
return (map->map_type != BPF_MAP_TYPE_HASH &&
|
|
map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
|
|
map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) ||
|
|
!(map->map_flags & BPF_F_NO_PREALLOC);
|
|
}
|
|
|
|
static int check_map_prog_compatibility(struct bpf_verifier_env *env,
|
|
struct bpf_map *map,
|
|
struct bpf_prog *prog)
|
|
|
|
{
|
|
/* Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use
|
|
* preallocated hash maps, since doing memory allocation
|
|
* in overflow_handler can crash depending on where nmi got
|
|
* triggered.
|
|
*/
|
|
if (prog->type == BPF_PROG_TYPE_PERF_EVENT) {
|
|
if (!check_map_prealloc(map)) {
|
|
verbose(env, "perf_event programs can only use preallocated hash map\n");
|
|
return -EINVAL;
|
|
}
|
|
if (map->inner_map_meta &&
|
|
!check_map_prealloc(map->inner_map_meta)) {
|
|
verbose(env, "perf_event programs can only use preallocated inner hash map\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(map)) &&
|
|
!bpf_offload_prog_map_match(prog, map)) {
|
|
verbose(env, "offload device mismatch between prog and map\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* look for pseudo eBPF instructions that access map FDs and
|
|
* replace them with actual map pointers
|
|
*/
|
|
static int replace_map_fd_with_map_ptr(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int i, j, err;
|
|
|
|
err = bpf_prog_calc_tag(env->prog);
|
|
if (err)
|
|
return err;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (BPF_CLASS(insn->code) == BPF_LDX &&
|
|
(BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
|
|
verbose(env, "BPF_LDX uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (BPF_CLASS(insn->code) == BPF_STX &&
|
|
((BPF_MODE(insn->code) != BPF_MEM &&
|
|
BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
|
|
verbose(env, "BPF_STX uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
|
|
struct bpf_map *map;
|
|
struct fd f;
|
|
|
|
if (i == insn_cnt - 1 || insn[1].code != 0 ||
|
|
insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
|
|
insn[1].off != 0) {
|
|
verbose(env, "invalid bpf_ld_imm64 insn\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn->src_reg == 0)
|
|
/* valid generic load 64-bit imm */
|
|
goto next_insn;
|
|
|
|
if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
|
|
verbose(env,
|
|
"unrecognized bpf_ld_imm64 insn\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
f = fdget(insn->imm);
|
|
map = __bpf_map_get(f);
|
|
if (IS_ERR(map)) {
|
|
verbose(env, "fd %d is not pointing to valid bpf_map\n",
|
|
insn->imm);
|
|
return PTR_ERR(map);
|
|
}
|
|
|
|
err = check_map_prog_compatibility(env, map, env->prog);
|
|
if (err) {
|
|
fdput(f);
|
|
return err;
|
|
}
|
|
|
|
/* store map pointer inside BPF_LD_IMM64 instruction */
|
|
insn[0].imm = (u32) (unsigned long) map;
|
|
insn[1].imm = ((u64) (unsigned long) map) >> 32;
|
|
|
|
/* check whether we recorded this map already */
|
|
for (j = 0; j < env->used_map_cnt; j++)
|
|
if (env->used_maps[j] == map) {
|
|
fdput(f);
|
|
goto next_insn;
|
|
}
|
|
|
|
if (env->used_map_cnt >= MAX_USED_MAPS) {
|
|
fdput(f);
|
|
return -E2BIG;
|
|
}
|
|
|
|
/* hold the map. If the program is rejected by verifier,
|
|
* the map will be released by release_maps() or it
|
|
* will be used by the valid program until it's unloaded
|
|
* and all maps are released in free_used_maps()
|
|
*/
|
|
map = bpf_map_inc(map, false);
|
|
if (IS_ERR(map)) {
|
|
fdput(f);
|
|
return PTR_ERR(map);
|
|
}
|
|
env->used_maps[env->used_map_cnt++] = map;
|
|
|
|
if (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE &&
|
|
bpf_cgroup_storage_assign(env->prog, map)) {
|
|
verbose(env,
|
|
"only one cgroup storage is allowed\n");
|
|
fdput(f);
|
|
return -EBUSY;
|
|
}
|
|
|
|
fdput(f);
|
|
next_insn:
|
|
insn++;
|
|
i++;
|
|
continue;
|
|
}
|
|
|
|
/* Basic sanity check before we invest more work here. */
|
|
if (!bpf_opcode_in_insntable(insn->code)) {
|
|
verbose(env, "unknown opcode %02x\n", insn->code);
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* now all pseudo BPF_LD_IMM64 instructions load valid
|
|
* 'struct bpf_map *' into a register instead of user map_fd.
|
|
* These pointers will be used later by verifier to validate map access.
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
/* drop refcnt of maps used by the rejected program */
|
|
static void release_maps(struct bpf_verifier_env *env)
|
|
{
|
|
int i;
|
|
|
|
if (env->prog->aux->cgroup_storage)
|
|
bpf_cgroup_storage_release(env->prog,
|
|
env->prog->aux->cgroup_storage);
|
|
|
|
for (i = 0; i < env->used_map_cnt; i++)
|
|
bpf_map_put(env->used_maps[i]);
|
|
}
|
|
|
|
/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
|
|
static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int i;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++)
|
|
if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
|
|
insn->src_reg = 0;
|
|
}
|
|
|
|
/* single env->prog->insni[off] instruction was replaced with the range
|
|
* insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
|
|
* [0, off) and [off, end) to new locations, so the patched range stays zero
|
|
*/
|
|
static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
|
|
u32 off, u32 cnt)
|
|
{
|
|
struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
|
|
int i;
|
|
|
|
if (cnt == 1)
|
|
return 0;
|
|
new_data = vzalloc(array_size(prog_len,
|
|
sizeof(struct bpf_insn_aux_data)));
|
|
if (!new_data)
|
|
return -ENOMEM;
|
|
memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
|
|
memcpy(new_data + off + cnt - 1, old_data + off,
|
|
sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
|
|
for (i = off; i < off + cnt - 1; i++)
|
|
new_data[i].seen = true;
|
|
env->insn_aux_data = new_data;
|
|
vfree(old_data);
|
|
return 0;
|
|
}
|
|
|
|
static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len)
|
|
{
|
|
int i;
|
|
|
|
if (len == 1)
|
|
return;
|
|
/* NOTE: fake 'exit' subprog should be updated as well. */
|
|
for (i = 0; i <= env->subprog_cnt; i++) {
|
|
if (env->subprog_info[i].start <= off)
|
|
continue;
|
|
env->subprog_info[i].start += len - 1;
|
|
}
|
|
}
|
|
|
|
static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
|
|
const struct bpf_insn *patch, u32 len)
|
|
{
|
|
struct bpf_prog *new_prog;
|
|
|
|
new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
|
|
if (!new_prog)
|
|
return NULL;
|
|
if (adjust_insn_aux_data(env, new_prog->len, off, len))
|
|
return NULL;
|
|
adjust_subprog_starts(env, off, len);
|
|
return new_prog;
|
|
}
|
|
|
|
/* The verifier does more data flow analysis than llvm and will not
|
|
* explore branches that are dead at run time. Malicious programs can
|
|
* have dead code too. Therefore replace all dead at-run-time code
|
|
* with 'ja -1'.
|
|
*
|
|
* Just nops are not optimal, e.g. if they would sit at the end of the
|
|
* program and through another bug we would manage to jump there, then
|
|
* we'd execute beyond program memory otherwise. Returning exception
|
|
* code also wouldn't work since we can have subprogs where the dead
|
|
* code could be located.
|
|
*/
|
|
static void sanitize_dead_code(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
|
|
struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1);
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
const int insn_cnt = env->prog->len;
|
|
int i;
|
|
|
|
for (i = 0; i < insn_cnt; i++) {
|
|
if (aux_data[i].seen)
|
|
continue;
|
|
memcpy(insn + i, &trap, sizeof(trap));
|
|
}
|
|
}
|
|
|
|
/* convert load instructions that access fields of 'struct __sk_buff'
|
|
* into sequence of instructions that access fields of 'struct sk_buff'
|
|
*/
|
|
static int convert_ctx_accesses(struct bpf_verifier_env *env)
|
|
{
|
|
const struct bpf_verifier_ops *ops = env->ops;
|
|
int i, cnt, size, ctx_field_size, delta = 0;
|
|
const int insn_cnt = env->prog->len;
|
|
struct bpf_insn insn_buf[16], *insn;
|
|
u32 target_size, size_default, off;
|
|
struct bpf_prog *new_prog;
|
|
enum bpf_access_type type;
|
|
bool is_narrower_load;
|
|
|
|
if (ops->gen_prologue) {
|
|
cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
|
|
env->prog);
|
|
if (cnt >= ARRAY_SIZE(insn_buf)) {
|
|
verbose(env, "bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
} else if (cnt) {
|
|
new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
env->prog = new_prog;
|
|
delta += cnt - 1;
|
|
}
|
|
}
|
|
|
|
if (!ops->convert_ctx_access || bpf_prog_is_dev_bound(env->prog->aux))
|
|
return 0;
|
|
|
|
insn = env->prog->insnsi + delta;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
|
|
insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
|
|
insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
|
|
insn->code == (BPF_LDX | BPF_MEM | BPF_DW))
|
|
type = BPF_READ;
|
|
else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
|
|
insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
|
|
insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
|
|
insn->code == (BPF_STX | BPF_MEM | BPF_DW))
|
|
type = BPF_WRITE;
|
|
else
|
|
continue;
|
|
|
|
if (type == BPF_WRITE &&
|
|
env->insn_aux_data[i + delta].sanitize_stack_off) {
|
|
struct bpf_insn patch[] = {
|
|
/* Sanitize suspicious stack slot with zero.
|
|
* There are no memory dependencies for this store,
|
|
* since it's only using frame pointer and immediate
|
|
* constant of zero
|
|
*/
|
|
BPF_ST_MEM(BPF_DW, BPF_REG_FP,
|
|
env->insn_aux_data[i + delta].sanitize_stack_off,
|
|
0),
|
|
/* the original STX instruction will immediately
|
|
* overwrite the same stack slot with appropriate value
|
|
*/
|
|
*insn,
|
|
};
|
|
|
|
cnt = ARRAY_SIZE(patch);
|
|
new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
env->prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
continue;
|
|
}
|
|
|
|
if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX)
|
|
continue;
|
|
|
|
ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
|
|
size = BPF_LDST_BYTES(insn);
|
|
|
|
/* If the read access is a narrower load of the field,
|
|
* convert to a 4/8-byte load, to minimum program type specific
|
|
* convert_ctx_access changes. If conversion is successful,
|
|
* we will apply proper mask to the result.
|
|
*/
|
|
is_narrower_load = size < ctx_field_size;
|
|
size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
|
|
off = insn->off;
|
|
if (is_narrower_load) {
|
|
u8 size_code;
|
|
|
|
if (type == BPF_WRITE) {
|
|
verbose(env, "bpf verifier narrow ctx access misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
size_code = BPF_H;
|
|
if (ctx_field_size == 4)
|
|
size_code = BPF_W;
|
|
else if (ctx_field_size == 8)
|
|
size_code = BPF_DW;
|
|
|
|
insn->off = off & ~(size_default - 1);
|
|
insn->code = BPF_LDX | BPF_MEM | size_code;
|
|
}
|
|
|
|
target_size = 0;
|
|
cnt = ops->convert_ctx_access(type, insn, insn_buf, env->prog,
|
|
&target_size);
|
|
if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
|
|
(ctx_field_size && !target_size)) {
|
|
verbose(env, "bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (is_narrower_load && size < target_size) {
|
|
u8 shift = (off & (size_default - 1)) * 8;
|
|
|
|
if (ctx_field_size <= 4) {
|
|
if (shift)
|
|
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH,
|
|
insn->dst_reg,
|
|
shift);
|
|
insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
|
|
(1 << size * 8) - 1);
|
|
} else {
|
|
if (shift)
|
|
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
|
|
insn->dst_reg,
|
|
shift);
|
|
insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
|
|
(1ULL << size * 8) - 1);
|
|
}
|
|
}
|
|
|
|
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
|
|
/* keep walking new program and skip insns we just inserted */
|
|
env->prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int jit_subprogs(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_prog *prog = env->prog, **func, *tmp;
|
|
int i, j, subprog_start, subprog_end = 0, len, subprog;
|
|
struct bpf_insn *insn;
|
|
void *old_bpf_func;
|
|
int err = -ENOMEM;
|
|
|
|
if (env->subprog_cnt <= 1)
|
|
return 0;
|
|
|
|
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
|
|
if (insn->code != (BPF_JMP | BPF_CALL) ||
|
|
insn->src_reg != BPF_PSEUDO_CALL)
|
|
continue;
|
|
/* Upon error here we cannot fall back to interpreter but
|
|
* need a hard reject of the program. Thus -EFAULT is
|
|
* propagated in any case.
|
|
*/
|
|
subprog = find_subprog(env, i + insn->imm + 1);
|
|
if (subprog < 0) {
|
|
WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
|
|
i + insn->imm + 1);
|
|
return -EFAULT;
|
|
}
|
|
/* temporarily remember subprog id inside insn instead of
|
|
* aux_data, since next loop will split up all insns into funcs
|
|
*/
|
|
insn->off = subprog;
|
|
/* remember original imm in case JIT fails and fallback
|
|
* to interpreter will be needed
|
|
*/
|
|
env->insn_aux_data[i].call_imm = insn->imm;
|
|
/* point imm to __bpf_call_base+1 from JITs point of view */
|
|
insn->imm = 1;
|
|
}
|
|
|
|
func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
|
|
if (!func)
|
|
goto out_undo_insn;
|
|
|
|
for (i = 0; i < env->subprog_cnt; i++) {
|
|
subprog_start = subprog_end;
|
|
subprog_end = env->subprog_info[i + 1].start;
|
|
|
|
len = subprog_end - subprog_start;
|
|
func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER);
|
|
if (!func[i])
|
|
goto out_free;
|
|
memcpy(func[i]->insnsi, &prog->insnsi[subprog_start],
|
|
len * sizeof(struct bpf_insn));
|
|
func[i]->type = prog->type;
|
|
func[i]->len = len;
|
|
if (bpf_prog_calc_tag(func[i]))
|
|
goto out_free;
|
|
func[i]->is_func = 1;
|
|
/* Use bpf_prog_F_tag to indicate functions in stack traces.
|
|
* Long term would need debug info to populate names
|
|
*/
|
|
func[i]->aux->name[0] = 'F';
|
|
func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
|
|
func[i]->jit_requested = 1;
|
|
func[i] = bpf_int_jit_compile(func[i]);
|
|
if (!func[i]->jited) {
|
|
err = -ENOTSUPP;
|
|
goto out_free;
|
|
}
|
|
cond_resched();
|
|
}
|
|
/* at this point all bpf functions were successfully JITed
|
|
* now populate all bpf_calls with correct addresses and
|
|
* run last pass of JIT
|
|
*/
|
|
for (i = 0; i < env->subprog_cnt; i++) {
|
|
insn = func[i]->insnsi;
|
|
for (j = 0; j < func[i]->len; j++, insn++) {
|
|
if (insn->code != (BPF_JMP | BPF_CALL) ||
|
|
insn->src_reg != BPF_PSEUDO_CALL)
|
|
continue;
|
|
subprog = insn->off;
|
|
insn->imm = (u64 (*)(u64, u64, u64, u64, u64))
|
|
func[subprog]->bpf_func -
|
|
__bpf_call_base;
|
|
}
|
|
|
|
/* we use the aux data to keep a list of the start addresses
|
|
* of the JITed images for each function in the program
|
|
*
|
|
* for some architectures, such as powerpc64, the imm field
|
|
* might not be large enough to hold the offset of the start
|
|
* address of the callee's JITed image from __bpf_call_base
|
|
*
|
|
* in such cases, we can lookup the start address of a callee
|
|
* by using its subprog id, available from the off field of
|
|
* the call instruction, as an index for this list
|
|
*/
|
|
func[i]->aux->func = func;
|
|
func[i]->aux->func_cnt = env->subprog_cnt;
|
|
}
|
|
for (i = 0; i < env->subprog_cnt; i++) {
|
|
old_bpf_func = func[i]->bpf_func;
|
|
tmp = bpf_int_jit_compile(func[i]);
|
|
if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
|
|
verbose(env, "JIT doesn't support bpf-to-bpf calls\n");
|
|
err = -ENOTSUPP;
|
|
goto out_free;
|
|
}
|
|
cond_resched();
|
|
}
|
|
|
|
/* finally lock prog and jit images for all functions and
|
|
* populate kallsysm
|
|
*/
|
|
for (i = 0; i < env->subprog_cnt; i++) {
|
|
bpf_prog_lock_ro(func[i]);
|
|
bpf_prog_kallsyms_add(func[i]);
|
|
}
|
|
|
|
/* Last step: make now unused interpreter insns from main
|
|
* prog consistent for later dump requests, so they can
|
|
* later look the same as if they were interpreted only.
|
|
*/
|
|
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
|
|
if (insn->code != (BPF_JMP | BPF_CALL) ||
|
|
insn->src_reg != BPF_PSEUDO_CALL)
|
|
continue;
|
|
insn->off = env->insn_aux_data[i].call_imm;
|
|
subprog = find_subprog(env, i + insn->off + 1);
|
|
insn->imm = subprog;
|
|
}
|
|
|
|
prog->jited = 1;
|
|
prog->bpf_func = func[0]->bpf_func;
|
|
prog->aux->func = func;
|
|
prog->aux->func_cnt = env->subprog_cnt;
|
|
return 0;
|
|
out_free:
|
|
for (i = 0; i < env->subprog_cnt; i++)
|
|
if (func[i])
|
|
bpf_jit_free(func[i]);
|
|
kfree(func);
|
|
out_undo_insn:
|
|
/* cleanup main prog to be interpreted */
|
|
prog->jit_requested = 0;
|
|
for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
|
|
if (insn->code != (BPF_JMP | BPF_CALL) ||
|
|
insn->src_reg != BPF_PSEUDO_CALL)
|
|
continue;
|
|
insn->off = 0;
|
|
insn->imm = env->insn_aux_data[i].call_imm;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int fixup_call_args(struct bpf_verifier_env *env)
|
|
{
|
|
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
|
|
struct bpf_prog *prog = env->prog;
|
|
struct bpf_insn *insn = prog->insnsi;
|
|
int i, depth;
|
|
#endif
|
|
int err;
|
|
|
|
err = 0;
|
|
if (env->prog->jit_requested) {
|
|
err = jit_subprogs(env);
|
|
if (err == 0)
|
|
return 0;
|
|
if (err == -EFAULT)
|
|
return err;
|
|
}
|
|
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
|
|
for (i = 0; i < prog->len; i++, insn++) {
|
|
if (insn->code != (BPF_JMP | BPF_CALL) ||
|
|
insn->src_reg != BPF_PSEUDO_CALL)
|
|
continue;
|
|
depth = get_callee_stack_depth(env, insn, i);
|
|
if (depth < 0)
|
|
return depth;
|
|
bpf_patch_call_args(insn, depth);
|
|
}
|
|
err = 0;
|
|
#endif
|
|
return err;
|
|
}
|
|
|
|
/* fixup insn->imm field of bpf_call instructions
|
|
* and inline eligible helpers as explicit sequence of BPF instructions
|
|
*
|
|
* this function is called after eBPF program passed verification
|
|
*/
|
|
static int fixup_bpf_calls(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_prog *prog = env->prog;
|
|
struct bpf_insn *insn = prog->insnsi;
|
|
const struct bpf_func_proto *fn;
|
|
const int insn_cnt = prog->len;
|
|
const struct bpf_map_ops *ops;
|
|
struct bpf_insn_aux_data *aux;
|
|
struct bpf_insn insn_buf[16];
|
|
struct bpf_prog *new_prog;
|
|
struct bpf_map *map_ptr;
|
|
int i, cnt, delta = 0;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) ||
|
|
insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
|
|
insn->code == (BPF_ALU | BPF_MOD | BPF_X) ||
|
|
insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
|
|
bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
|
|
struct bpf_insn mask_and_div[] = {
|
|
BPF_MOV32_REG(insn->src_reg, insn->src_reg),
|
|
/* Rx div 0 -> 0 */
|
|
BPF_JMP_IMM(BPF_JNE, insn->src_reg, 0, 2),
|
|
BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg),
|
|
BPF_JMP_IMM(BPF_JA, 0, 0, 1),
|
|
*insn,
|
|
};
|
|
struct bpf_insn mask_and_mod[] = {
|
|
BPF_MOV32_REG(insn->src_reg, insn->src_reg),
|
|
/* Rx mod 0 -> Rx */
|
|
BPF_JMP_IMM(BPF_JEQ, insn->src_reg, 0, 1),
|
|
*insn,
|
|
};
|
|
struct bpf_insn *patchlet;
|
|
|
|
if (insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
|
|
insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
|
|
patchlet = mask_and_div + (is64 ? 1 : 0);
|
|
cnt = ARRAY_SIZE(mask_and_div) - (is64 ? 1 : 0);
|
|
} else {
|
|
patchlet = mask_and_mod + (is64 ? 1 : 0);
|
|
cnt = ARRAY_SIZE(mask_and_mod) - (is64 ? 1 : 0);
|
|
}
|
|
|
|
new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
env->prog = prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
continue;
|
|
}
|
|
|
|
if (BPF_CLASS(insn->code) == BPF_LD &&
|
|
(BPF_MODE(insn->code) == BPF_ABS ||
|
|
BPF_MODE(insn->code) == BPF_IND)) {
|
|
cnt = env->ops->gen_ld_abs(insn, insn_buf);
|
|
if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
|
|
verbose(env, "bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
env->prog = prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
continue;
|
|
}
|
|
|
|
if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) ||
|
|
insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) {
|
|
const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X;
|
|
const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X;
|
|
struct bpf_insn insn_buf[16];
|
|
struct bpf_insn *patch = &insn_buf[0];
|
|
bool issrc, isneg;
|
|
u32 off_reg;
|
|
|
|
aux = &env->insn_aux_data[i + delta];
|
|
if (!aux->alu_state ||
|
|
aux->alu_state == BPF_ALU_NON_POINTER)
|
|
continue;
|
|
|
|
isneg = aux->alu_state & BPF_ALU_NEG_VALUE;
|
|
issrc = (aux->alu_state & BPF_ALU_SANITIZE) ==
|
|
BPF_ALU_SANITIZE_SRC;
|
|
|
|
off_reg = issrc ? insn->src_reg : insn->dst_reg;
|
|
if (isneg)
|
|
*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
|
|
*patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
|
|
*patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg);
|
|
*patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg);
|
|
*patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0);
|
|
*patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63);
|
|
*patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg);
|
|
if (!issrc)
|
|
*patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg);
|
|
insn->src_reg = BPF_REG_AX;
|
|
if (isneg)
|
|
insn->code = insn->code == code_add ?
|
|
code_sub : code_add;
|
|
*patch++ = *insn;
|
|
if (issrc && isneg)
|
|
*patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
|
|
cnt = patch - insn_buf;
|
|
|
|
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
env->prog = prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
continue;
|
|
}
|
|
|
|
if (insn->code != (BPF_JMP | BPF_CALL))
|
|
continue;
|
|
if (insn->src_reg == BPF_PSEUDO_CALL)
|
|
continue;
|
|
|
|
if (insn->imm == BPF_FUNC_get_route_realm)
|
|
prog->dst_needed = 1;
|
|
if (insn->imm == BPF_FUNC_get_prandom_u32)
|
|
bpf_user_rnd_init_once();
|
|
if (insn->imm == BPF_FUNC_override_return)
|
|
prog->kprobe_override = 1;
|
|
if (insn->imm == BPF_FUNC_tail_call) {
|
|
/* If we tail call into other programs, we
|
|
* cannot make any assumptions since they can
|
|
* be replaced dynamically during runtime in
|
|
* the program array.
|
|
*/
|
|
prog->cb_access = 1;
|
|
env->prog->aux->stack_depth = MAX_BPF_STACK;
|
|
|
|
/* mark bpf_tail_call as different opcode to avoid
|
|
* conditional branch in the interpeter for every normal
|
|
* call and to prevent accidental JITing by JIT compiler
|
|
* that doesn't support bpf_tail_call yet
|
|
*/
|
|
insn->imm = 0;
|
|
insn->code = BPF_JMP | BPF_TAIL_CALL;
|
|
|
|
aux = &env->insn_aux_data[i + delta];
|
|
if (!bpf_map_ptr_unpriv(aux))
|
|
continue;
|
|
|
|
/* instead of changing every JIT dealing with tail_call
|
|
* emit two extra insns:
|
|
* if (index >= max_entries) goto out;
|
|
* index &= array->index_mask;
|
|
* to avoid out-of-bounds cpu speculation
|
|
*/
|
|
if (bpf_map_ptr_poisoned(aux)) {
|
|
verbose(env, "tail_call abusing map_ptr\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
map_ptr = BPF_MAP_PTR(aux->map_state);
|
|
insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
|
|
map_ptr->max_entries, 2);
|
|
insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
|
|
container_of(map_ptr,
|
|
struct bpf_array,
|
|
map)->index_mask);
|
|
insn_buf[2] = *insn;
|
|
cnt = 3;
|
|
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
env->prog = prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
continue;
|
|
}
|
|
|
|
/* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
|
|
* and other inlining handlers are currently limited to 64 bit
|
|
* only.
|
|
*/
|
|
if (prog->jit_requested && BITS_PER_LONG == 64 &&
|
|
(insn->imm == BPF_FUNC_map_lookup_elem ||
|
|
insn->imm == BPF_FUNC_map_update_elem ||
|
|
insn->imm == BPF_FUNC_map_delete_elem)) {
|
|
aux = &env->insn_aux_data[i + delta];
|
|
if (bpf_map_ptr_poisoned(aux))
|
|
goto patch_call_imm;
|
|
|
|
map_ptr = BPF_MAP_PTR(aux->map_state);
|
|
ops = map_ptr->ops;
|
|
if (insn->imm == BPF_FUNC_map_lookup_elem &&
|
|
ops->map_gen_lookup) {
|
|
cnt = ops->map_gen_lookup(map_ptr, insn_buf);
|
|
if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
|
|
verbose(env, "bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
new_prog = bpf_patch_insn_data(env, i + delta,
|
|
insn_buf, cnt);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
delta += cnt - 1;
|
|
env->prog = prog = new_prog;
|
|
insn = new_prog->insnsi + i + delta;
|
|
continue;
|
|
}
|
|
|
|
BUILD_BUG_ON(!__same_type(ops->map_lookup_elem,
|
|
(void *(*)(struct bpf_map *map, void *key))NULL));
|
|
BUILD_BUG_ON(!__same_type(ops->map_delete_elem,
|
|
(int (*)(struct bpf_map *map, void *key))NULL));
|
|
BUILD_BUG_ON(!__same_type(ops->map_update_elem,
|
|
(int (*)(struct bpf_map *map, void *key, void *value,
|
|
u64 flags))NULL));
|
|
switch (insn->imm) {
|
|
case BPF_FUNC_map_lookup_elem:
|
|
insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) -
|
|
__bpf_call_base;
|
|
continue;
|
|
case BPF_FUNC_map_update_elem:
|
|
insn->imm = BPF_CAST_CALL(ops->map_update_elem) -
|
|
__bpf_call_base;
|
|
continue;
|
|
case BPF_FUNC_map_delete_elem:
|
|
insn->imm = BPF_CAST_CALL(ops->map_delete_elem) -
|
|
__bpf_call_base;
|
|
continue;
|
|
}
|
|
|
|
goto patch_call_imm;
|
|
}
|
|
|
|
patch_call_imm:
|
|
fn = env->ops->get_func_proto(insn->imm, env->prog);
|
|
/* all functions that have prototype and verifier allowed
|
|
* programs to call them, must be real in-kernel functions
|
|
*/
|
|
if (!fn->func) {
|
|
verbose(env,
|
|
"kernel subsystem misconfigured func %s#%d\n",
|
|
func_id_name(insn->imm), insn->imm);
|
|
return -EFAULT;
|
|
}
|
|
insn->imm = fn->func - __bpf_call_base;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void free_states(struct bpf_verifier_env *env)
|
|
{
|
|
struct bpf_verifier_state_list *sl, *sln;
|
|
int i;
|
|
|
|
if (!env->explored_states)
|
|
return;
|
|
|
|
for (i = 0; i < env->prog->len; i++) {
|
|
sl = env->explored_states[i];
|
|
|
|
if (sl)
|
|
while (sl != STATE_LIST_MARK) {
|
|
sln = sl->next;
|
|
free_verifier_state(&sl->state, false);
|
|
kfree(sl);
|
|
sl = sln;
|
|
}
|
|
}
|
|
|
|
kfree(env->explored_states);
|
|
}
|
|
|
|
int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
|
|
{
|
|
struct bpf_verifier_env *env;
|
|
struct bpf_verifier_log *log;
|
|
int ret = -EINVAL;
|
|
|
|
/* no program is valid */
|
|
if (ARRAY_SIZE(bpf_verifier_ops) == 0)
|
|
return -EINVAL;
|
|
|
|
/* 'struct bpf_verifier_env' can be global, but since it's not small,
|
|
* allocate/free it every time bpf_check() is called
|
|
*/
|
|
env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
|
|
if (!env)
|
|
return -ENOMEM;
|
|
log = &env->log;
|
|
|
|
env->insn_aux_data =
|
|
vzalloc(array_size(sizeof(struct bpf_insn_aux_data),
|
|
(*prog)->len));
|
|
ret = -ENOMEM;
|
|
if (!env->insn_aux_data)
|
|
goto err_free_env;
|
|
env->prog = *prog;
|
|
env->ops = bpf_verifier_ops[env->prog->type];
|
|
|
|
/* grab the mutex to protect few globals used by verifier */
|
|
mutex_lock(&bpf_verifier_lock);
|
|
|
|
if (attr->log_level || attr->log_buf || attr->log_size) {
|
|
/* user requested verbose verifier output
|
|
* and supplied buffer to store the verification trace
|
|
*/
|
|
log->level = attr->log_level;
|
|
log->ubuf = (char __user *) (unsigned long) attr->log_buf;
|
|
log->len_total = attr->log_size;
|
|
|
|
ret = -EINVAL;
|
|
/* log attributes have to be sane */
|
|
if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 ||
|
|
!log->level || !log->ubuf)
|
|
goto err_unlock;
|
|
}
|
|
|
|
env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
|
|
if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
|
|
env->strict_alignment = true;
|
|
|
|
ret = replace_map_fd_with_map_ptr(env);
|
|
if (ret < 0)
|
|
goto skip_full_check;
|
|
|
|
if (bpf_prog_is_dev_bound(env->prog->aux)) {
|
|
ret = bpf_prog_offload_verifier_prep(env);
|
|
if (ret)
|
|
goto skip_full_check;
|
|
}
|
|
|
|
env->explored_states = kcalloc(env->prog->len,
|
|
sizeof(struct bpf_verifier_state_list *),
|
|
GFP_USER);
|
|
ret = -ENOMEM;
|
|
if (!env->explored_states)
|
|
goto skip_full_check;
|
|
|
|
env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
|
|
|
|
ret = check_cfg(env);
|
|
if (ret < 0)
|
|
goto skip_full_check;
|
|
|
|
ret = do_check(env);
|
|
if (env->cur_state) {
|
|
free_verifier_state(env->cur_state, true);
|
|
env->cur_state = NULL;
|
|
}
|
|
|
|
skip_full_check:
|
|
while (!pop_stack(env, NULL, NULL));
|
|
free_states(env);
|
|
|
|
if (ret == 0)
|
|
sanitize_dead_code(env);
|
|
|
|
if (ret == 0)
|
|
ret = check_max_stack_depth(env);
|
|
|
|
if (ret == 0)
|
|
/* program is valid, convert *(u32*)(ctx + off) accesses */
|
|
ret = convert_ctx_accesses(env);
|
|
|
|
if (ret == 0)
|
|
ret = fixup_bpf_calls(env);
|
|
|
|
if (ret == 0)
|
|
ret = fixup_call_args(env);
|
|
|
|
if (log->level && bpf_verifier_log_full(log))
|
|
ret = -ENOSPC;
|
|
if (log->level && !log->ubuf) {
|
|
ret = -EFAULT;
|
|
goto err_release_maps;
|
|
}
|
|
|
|
if (ret == 0 && env->used_map_cnt) {
|
|
/* if program passed verifier, update used_maps in bpf_prog_info */
|
|
env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
|
|
sizeof(env->used_maps[0]),
|
|
GFP_KERNEL);
|
|
|
|
if (!env->prog->aux->used_maps) {
|
|
ret = -ENOMEM;
|
|
goto err_release_maps;
|
|
}
|
|
|
|
memcpy(env->prog->aux->used_maps, env->used_maps,
|
|
sizeof(env->used_maps[0]) * env->used_map_cnt);
|
|
env->prog->aux->used_map_cnt = env->used_map_cnt;
|
|
|
|
/* program is valid. Convert pseudo bpf_ld_imm64 into generic
|
|
* bpf_ld_imm64 instructions
|
|
*/
|
|
convert_pseudo_ld_imm64(env);
|
|
}
|
|
|
|
err_release_maps:
|
|
if (!env->prog->aux->used_maps)
|
|
/* if we didn't copy map pointers into bpf_prog_info, release
|
|
* them now. Otherwise free_used_maps() will release them.
|
|
*/
|
|
release_maps(env);
|
|
*prog = env->prog;
|
|
err_unlock:
|
|
mutex_unlock(&bpf_verifier_lock);
|
|
vfree(env->insn_aux_data);
|
|
err_free_env:
|
|
kfree(env);
|
|
return ret;
|
|
}
|