137 lines
2.9 KiB
C
137 lines
2.9 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* iopl.c - Test case for a Linux on Xen 64-bit bug
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* Copyright (c) 2015 Andrew Lutomirski
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*/
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#define _GNU_SOURCE
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#include <err.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <signal.h>
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#include <setjmp.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <stdbool.h>
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#include <sched.h>
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#include <sys/io.h>
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static int nerrs = 0;
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static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
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int flags)
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{
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struct sigaction sa;
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memset(&sa, 0, sizeof(sa));
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sa.sa_sigaction = handler;
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sa.sa_flags = SA_SIGINFO | flags;
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sigemptyset(&sa.sa_mask);
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if (sigaction(sig, &sa, 0))
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err(1, "sigaction");
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}
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static jmp_buf jmpbuf;
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static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
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{
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siglongjmp(jmpbuf, 1);
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}
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int main(void)
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{
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cpu_set_t cpuset;
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CPU_ZERO(&cpuset);
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CPU_SET(0, &cpuset);
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if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
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err(1, "sched_setaffinity to CPU 0");
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/* Probe for iopl support. Note that iopl(0) works even as nonroot. */
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if (iopl(3) != 0) {
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printf("[OK]\tiopl(3) failed (%d) -- try running as root\n",
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errno);
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return 0;
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}
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/* Restore our original state prior to starting the test. */
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if (iopl(0) != 0)
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err(1, "iopl(0)");
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pid_t child = fork();
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if (child == -1)
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err(1, "fork");
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if (child == 0) {
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printf("\tchild: set IOPL to 3\n");
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if (iopl(3) != 0)
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err(1, "iopl");
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printf("[RUN]\tchild: write to 0x80\n");
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asm volatile ("outb %%al, $0x80" : : "a" (0));
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return 0;
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} else {
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int status;
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if (waitpid(child, &status, 0) != child ||
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!WIFEXITED(status)) {
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printf("[FAIL]\tChild died\n");
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nerrs++;
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} else if (WEXITSTATUS(status) != 0) {
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printf("[FAIL]\tChild failed\n");
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nerrs++;
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} else {
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printf("[OK]\tChild succeeded\n");
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}
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}
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printf("[RUN]\tparent: write to 0x80 (should fail)\n");
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sethandler(SIGSEGV, sigsegv, 0);
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if (sigsetjmp(jmpbuf, 1) != 0) {
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printf("[OK]\twrite was denied\n");
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} else {
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asm volatile ("outb %%al, $0x80" : : "a" (0));
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printf("[FAIL]\twrite was allowed\n");
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nerrs++;
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}
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/* Test the capability checks. */
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printf("\tiopl(3)\n");
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if (iopl(3) != 0)
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err(1, "iopl(3)");
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printf("\tDrop privileges\n");
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if (setresuid(1, 1, 1) != 0) {
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printf("[WARN]\tDropping privileges failed\n");
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goto done;
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}
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printf("[RUN]\tiopl(3) unprivileged but with IOPL==3\n");
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if (iopl(3) != 0) {
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printf("[FAIL]\tiopl(3) should work if iopl is already 3 even if unprivileged\n");
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nerrs++;
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}
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printf("[RUN]\tiopl(0) unprivileged\n");
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if (iopl(0) != 0) {
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printf("[FAIL]\tiopl(0) should work if iopl is already 3 even if unprivileged\n");
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nerrs++;
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}
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printf("[RUN]\tiopl(3) unprivileged\n");
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if (iopl(3) == 0) {
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printf("[FAIL]\tiopl(3) should fail if when unprivileged if iopl==0\n");
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nerrs++;
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} else {
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printf("[OK]\tFailed as expected\n");
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}
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done:
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return nerrs ? 1 : 0;
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}
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