295 lines
7.1 KiB
C
295 lines
7.1 KiB
C
/*
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* Network interface table.
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*
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* Network interfaces (devices) do not have a security field, so we
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* maintain a table associating each interface with a SID.
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*
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* Author: James Morris <jmorris@redhat.com>
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*
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* Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
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* Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
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* Paul Moore <paul@paul-moore.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2,
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* as published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/stddef.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/notifier.h>
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#include <linux/netdevice.h>
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#include <linux/rcupdate.h>
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#include <net/net_namespace.h>
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#include "security.h"
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#include "objsec.h"
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#include "netif.h"
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#define SEL_NETIF_HASH_SIZE 64
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#define SEL_NETIF_HASH_MAX 1024
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struct sel_netif {
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struct list_head list;
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struct netif_security_struct nsec;
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struct rcu_head rcu_head;
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};
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static u32 sel_netif_total;
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static LIST_HEAD(sel_netif_list);
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static DEFINE_SPINLOCK(sel_netif_lock);
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static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
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/**
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* sel_netif_hashfn - Hashing function for the interface table
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* @ns: the network namespace
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* @ifindex: the network interface
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*
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* Description:
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* This is the hashing function for the network interface table, it returns the
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* bucket number for the given interface.
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*
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*/
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static inline u32 sel_netif_hashfn(const struct net *ns, int ifindex)
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{
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return (((uintptr_t)ns + ifindex) & (SEL_NETIF_HASH_SIZE - 1));
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}
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/**
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* sel_netif_find - Search for an interface record
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* @ns: the network namespace
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* @ifindex: the network interface
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*
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* Description:
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* Search the network interface table and return the record matching @ifindex.
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* If an entry can not be found in the table return NULL.
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*
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*/
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static inline struct sel_netif *sel_netif_find(const struct net *ns,
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int ifindex)
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{
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int idx = sel_netif_hashfn(ns, ifindex);
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struct sel_netif *netif;
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list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
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if (net_eq(netif->nsec.ns, ns) &&
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netif->nsec.ifindex == ifindex)
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return netif;
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return NULL;
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}
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/**
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* sel_netif_insert - Insert a new interface into the table
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* @netif: the new interface record
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*
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* Description:
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* Add a new interface record to the network interface hash table. Returns
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* zero on success, negative values on failure.
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*
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*/
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static int sel_netif_insert(struct sel_netif *netif)
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{
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int idx;
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if (sel_netif_total >= SEL_NETIF_HASH_MAX)
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return -ENOSPC;
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idx = sel_netif_hashfn(netif->nsec.ns, netif->nsec.ifindex);
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list_add_rcu(&netif->list, &sel_netif_hash[idx]);
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sel_netif_total++;
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return 0;
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}
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/**
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* sel_netif_destroy - Remove an interface record from the table
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* @netif: the existing interface record
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*
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* Description:
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* Remove an existing interface record from the network interface table.
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*
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*/
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static void sel_netif_destroy(struct sel_netif *netif)
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{
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list_del_rcu(&netif->list);
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sel_netif_total--;
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kfree_rcu(netif, rcu_head);
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}
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/**
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* sel_netif_sid_slow - Lookup the SID of a network interface using the policy
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* @ns: the network namespace
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* @ifindex: the network interface
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* @sid: interface SID
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*
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* Description:
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* This function determines the SID of a network interface by quering the
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* security policy. The result is added to the network interface table to
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* speedup future queries. Returns zero on success, negative values on
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* failure.
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*
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*/
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static int sel_netif_sid_slow(struct net *ns, int ifindex, u32 *sid)
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{
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int ret;
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struct sel_netif *netif;
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struct sel_netif *new = NULL;
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struct net_device *dev;
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/* NOTE: we always use init's network namespace since we don't
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* currently support containers */
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dev = dev_get_by_index(ns, ifindex);
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if (unlikely(dev == NULL)) {
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pr_warn("SELinux: failure in %s(), invalid network interface (%d)\n",
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__func__, ifindex);
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return -ENOENT;
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}
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spin_lock_bh(&sel_netif_lock);
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netif = sel_netif_find(ns, ifindex);
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if (netif != NULL) {
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*sid = netif->nsec.sid;
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ret = 0;
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goto out;
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}
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new = kzalloc(sizeof(*new), GFP_ATOMIC);
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if (new == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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ret = security_netif_sid(&selinux_state, dev->name, &new->nsec.sid);
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if (ret != 0)
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goto out;
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new->nsec.ns = ns;
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new->nsec.ifindex = ifindex;
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ret = sel_netif_insert(new);
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if (ret != 0)
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goto out;
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*sid = new->nsec.sid;
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out:
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spin_unlock_bh(&sel_netif_lock);
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dev_put(dev);
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if (unlikely(ret)) {
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pr_warn("SELinux: failure in %s(), unable to determine network interface label (%d)\n",
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__func__, ifindex);
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kfree(new);
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}
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return ret;
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}
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/**
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* sel_netif_sid - Lookup the SID of a network interface
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* @ns: the network namespace
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* @ifindex: the network interface
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* @sid: interface SID
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*
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* Description:
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* This function determines the SID of a network interface using the fastest
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* method possible. First the interface table is queried, but if an entry
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* can't be found then the policy is queried and the result is added to the
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* table to speedup future queries. Returns zero on success, negative values
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* on failure.
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*
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*/
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int sel_netif_sid(struct net *ns, int ifindex, u32 *sid)
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{
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struct sel_netif *netif;
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rcu_read_lock();
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netif = sel_netif_find(ns, ifindex);
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if (likely(netif != NULL)) {
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*sid = netif->nsec.sid;
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rcu_read_unlock();
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return 0;
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}
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rcu_read_unlock();
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return sel_netif_sid_slow(ns, ifindex, sid);
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}
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/**
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* sel_netif_kill - Remove an entry from the network interface table
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* @ns: the network namespace
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* @ifindex: the network interface
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*
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* Description:
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* This function removes the entry matching @ifindex from the network interface
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* table if it exists.
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*
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*/
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static void sel_netif_kill(const struct net *ns, int ifindex)
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{
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struct sel_netif *netif;
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rcu_read_lock();
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spin_lock_bh(&sel_netif_lock);
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netif = sel_netif_find(ns, ifindex);
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if (netif)
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sel_netif_destroy(netif);
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spin_unlock_bh(&sel_netif_lock);
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rcu_read_unlock();
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}
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/**
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* sel_netif_flush - Flush the entire network interface table
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*
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* Description:
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* Remove all entries from the network interface table.
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*
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*/
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void sel_netif_flush(void)
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{
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int idx;
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struct sel_netif *netif;
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spin_lock_bh(&sel_netif_lock);
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for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
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list_for_each_entry(netif, &sel_netif_hash[idx], list)
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sel_netif_destroy(netif);
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spin_unlock_bh(&sel_netif_lock);
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}
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static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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if (event == NETDEV_DOWN)
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sel_netif_kill(dev_net(dev), dev->ifindex);
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return NOTIFY_DONE;
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}
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static struct notifier_block sel_netif_netdev_notifier = {
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.notifier_call = sel_netif_netdev_notifier_handler,
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};
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static __init int sel_netif_init(void)
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{
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int i;
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// [ SEC_SELINUX_PORTING_COMMON
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#ifdef CONFIG_ALWAYS_ENFORCE
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selinux_enabled = 1;
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#endif
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// ] SEC_SELINUX_PORTING_COMMON
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if (!selinux_enabled)
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return 0;
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for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
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INIT_LIST_HEAD(&sel_netif_hash[i]);
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register_netdevice_notifier(&sel_netif_netdev_notifier);
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return 0;
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}
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__initcall(sel_netif_init);
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