// SPDX-License-Identifier: GPL-2.0-only /* * Network interface table. * * Network interfaces (devices) do not have a security field, so we * maintain a table associating each interface with a SID. * * Author: James Morris <jmorris@redhat.com> * * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com> * Copyright (C) 2007 Hewlett-Packard Development Company, L.P. * Paul Moore <paul@paul-moore.com> */ #include <linux/init.h> #include <linux/types.h> #include <linux/slab.h> #include <linux/stddef.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/notifier.h> #include <linux/netdevice.h> #include <linux/rcupdate.h> #include <net/net_namespace.h> #include "security.h" #include "objsec.h" #include "netif.h" #define SEL_NETIF_HASH_SIZE 64 #define SEL_NETIF_HASH_MAX 1024 struct sel_netif { struct list_head list; struct netif_security_struct nsec; struct rcu_head rcu_head; }; static u32 sel_netif_total; static DEFINE_SPINLOCK(sel_netif_lock); static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE]; /** * sel_netif_hashfn - Hashing function for the interface table * @ns: the network namespace * @ifindex: the network interface * * Description: * This is the hashing function for the network interface table, it returns the * bucket number for the given interface. * */ static inline u32 sel_netif_hashfn(const struct net *ns, int ifindex) { return (((uintptr_t)ns + ifindex) & (SEL_NETIF_HASH_SIZE - 1)); } /** * sel_netif_find - Search for an interface record * @ns: the network namespace * @ifindex: the network interface * * Description: * Search the network interface table and return the record matching @ifindex. * If an entry can not be found in the table return NULL. * */ static inline struct sel_netif *sel_netif_find(const struct net *ns, int ifindex) { int idx = sel_netif_hashfn(ns, ifindex); struct sel_netif *netif; list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list) if (net_eq(netif->nsec.ns, ns) && netif->nsec.ifindex == ifindex) return netif; return NULL; } /** * sel_netif_insert - Insert a new interface into the table * @netif: the new interface record * * Description: * Add a new interface record to the network interface hash table. Returns * zero on success, negative values on failure. * */ static int sel_netif_insert(struct sel_netif *netif) { int idx; if (sel_netif_total >= SEL_NETIF_HASH_MAX) return -ENOSPC; idx = sel_netif_hashfn(netif->nsec.ns, netif->nsec.ifindex); list_add_rcu(&netif->list, &sel_netif_hash[idx]); sel_netif_total++; return 0; } /** * sel_netif_destroy - Remove an interface record from the table * @netif: the existing interface record * * Description: * Remove an existing interface record from the network interface table. * */ static void sel_netif_destroy(struct sel_netif *netif) { list_del_rcu(&netif->list); sel_netif_total--; kfree_rcu(netif, rcu_head); } /** * sel_netif_sid_slow - Lookup the SID of a network interface using the policy * @ns: the network namespace * @ifindex: the network interface * @sid: interface SID * * Description: * This function determines the SID of a network interface by querying the * security policy. The result is added to the network interface table to * speedup future queries. Returns zero on success, negative values on * failure. * */ static int sel_netif_sid_slow(struct net *ns, int ifindex, u32 *sid) { int ret = 0; struct sel_netif *netif; struct sel_netif *new; struct net_device *dev; /* NOTE: we always use init's network namespace since we don't * currently support containers */ dev = dev_get_by_index(ns, ifindex); if (unlikely(dev == NULL)) { pr_warn("SELinux: failure in %s(), invalid network interface (%d)\n", __func__, ifindex); return -ENOENT; } spin_lock_bh(&sel_netif_lock); netif = sel_netif_find(ns, ifindex); if (netif != NULL) { *sid = netif->nsec.sid; goto out; } ret = security_netif_sid(&selinux_state, dev->name, sid); if (ret != 0) goto out; new = kzalloc(sizeof(*new), GFP_ATOMIC); if (new) { new->nsec.ns = ns; new->nsec.ifindex = ifindex; new->nsec.sid = *sid; if (sel_netif_insert(new)) kfree(new); } out: spin_unlock_bh(&sel_netif_lock); dev_put(dev); if (unlikely(ret)) pr_warn("SELinux: failure in %s(), unable to determine network interface label (%d)\n", __func__, ifindex); return ret; } /** * sel_netif_sid - Lookup the SID of a network interface * @ns: the network namespace * @ifindex: the network interface * @sid: interface SID * * Description: * This function determines the SID of a network interface using the fastest * method possible. First the interface table is queried, but if an entry * can't be found then the policy is queried and the result is added to the * table to speedup future queries. Returns zero on success, negative values * on failure. * */ int sel_netif_sid(struct net *ns, int ifindex, u32 *sid) { struct sel_netif *netif; rcu_read_lock(); netif = sel_netif_find(ns, ifindex); if (likely(netif != NULL)) { *sid = netif->nsec.sid; rcu_read_unlock(); return 0; } rcu_read_unlock(); return sel_netif_sid_slow(ns, ifindex, sid); } /** * sel_netif_kill - Remove an entry from the network interface table * @ns: the network namespace * @ifindex: the network interface * * Description: * This function removes the entry matching @ifindex from the network interface * table if it exists. * */ static void sel_netif_kill(const struct net *ns, int ifindex) { struct sel_netif *netif; rcu_read_lock(); spin_lock_bh(&sel_netif_lock); netif = sel_netif_find(ns, ifindex); if (netif) sel_netif_destroy(netif); spin_unlock_bh(&sel_netif_lock); rcu_read_unlock(); } /** * sel_netif_flush - Flush the entire network interface table * * Description: * Remove all entries from the network interface table. * */ void sel_netif_flush(void) { int idx; struct sel_netif *netif; spin_lock_bh(&sel_netif_lock); for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++) list_for_each_entry(netif, &sel_netif_hash[idx], list) sel_netif_destroy(netif); spin_unlock_bh(&sel_netif_lock); } static int sel_netif_netdev_notifier_handler(struct notifier_block *this, unsigned long event, void *ptr) { struct net_device *dev = netdev_notifier_info_to_dev(ptr); if (event == NETDEV_DOWN) sel_netif_kill(dev_net(dev), dev->ifindex); return NOTIFY_DONE; } static struct notifier_block sel_netif_netdev_notifier = { .notifier_call = sel_netif_netdev_notifier_handler, }; static __init int sel_netif_init(void) { int i; if (!selinux_enabled_boot) return 0; for (i = 0; i < SEL_NETIF_HASH_SIZE; i++) INIT_LIST_HEAD(&sel_netif_hash[i]); register_netdevice_notifier(&sel_netif_netdev_notifier); return 0; } __initcall(sel_netif_init);