/* * 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.moore@hp.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2, * as published by the Free Software Foundation. */ #include <linux/init.h> #include <linux/types.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 LIST_HEAD(sel_netif_list); 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 * @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(int ifindex) { return (ifindex & (SEL_NETIF_HASH_SIZE - 1)); } /** * sel_netif_find - Search for an interface record * @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(int ifindex) { int idx = sel_netif_hashfn(ifindex); struct sel_netif *netif; list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list) /* all of the devices should normally fit in the hash, so we * optimize for that case */ if (likely(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.ifindex); list_add_rcu(&netif->list, &sel_netif_hash[idx]); sel_netif_total++; return 0; } /** * sel_netif_free - Frees an interface entry * @p: the entry's RCU field * * Description: * This function is designed to be used as a callback to the call_rcu() * function so that memory allocated to a hash table interface entry can be * released safely. * */ static void sel_netif_free(struct rcu_head *p) { struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head); kfree(netif); } /** * 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--; call_rcu(&netif->rcu_head, sel_netif_free); } /** * sel_netif_sid_slow - Lookup the SID of a network interface using the policy * @ifindex: the network interface * @sid: interface SID * * Description: * This function determines the SID of a network interface by quering 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(int ifindex, u32 *sid) { int ret; struct sel_netif *netif; struct sel_netif *new = NULL; struct net_device *dev; /* NOTE: we always use init's network namespace since we don't * currently support containers */ dev = dev_get_by_index(&init_net, ifindex); if (unlikely(dev == NULL)) { printk(KERN_WARNING "SELinux: failure in sel_netif_sid_slow()," " invalid network interface (%d)\n", ifindex); return -ENOENT; } spin_lock_bh(&sel_netif_lock); netif = sel_netif_find(ifindex); if (netif != NULL) { *sid = netif->nsec.sid; ret = 0; goto out; } new = kzalloc(sizeof(*new), GFP_ATOMIC); if (new == NULL) { ret = -ENOMEM; goto out; } ret = security_netif_sid(dev->name, &new->nsec.sid); if (ret != 0) goto out; new->nsec.ifindex = ifindex; ret = sel_netif_insert(new); if (ret != 0) goto out; *sid = new->nsec.sid; out: spin_unlock_bh(&sel_netif_lock); dev_put(dev); if (unlikely(ret)) { printk(KERN_WARNING "SELinux: failure in sel_netif_sid_slow()," " unable to determine network interface label (%d)\n", ifindex); kfree(new); } return ret; } /** * sel_netif_sid - Lookup the SID of a network interface * @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(int ifindex, u32 *sid) { struct sel_netif *netif; rcu_read_lock(); netif = sel_netif_find(ifindex); if (likely(netif != NULL)) { *sid = netif->nsec.sid; rcu_read_unlock(); return 0; } rcu_read_unlock(); return sel_netif_sid_slow(ifindex, sid); } /** * sel_netif_kill - Remove an entry from the network interface table * @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(int ifindex) { struct sel_netif *netif; rcu_read_lock(); spin_lock_bh(&sel_netif_lock); netif = sel_netif_find(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. * */ static 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_avc_callback(u32 event, u32 ssid, u32 tsid, u16 class, u32 perms, u32 *retained) { if (event == AVC_CALLBACK_RESET) { sel_netif_flush(); synchronize_net(); } return 0; } static int sel_netif_netdev_notifier_handler(struct notifier_block *this, unsigned long event, void *ptr) { struct net_device *dev = ptr; if (dev_net(dev) != &init_net) return NOTIFY_DONE; if (event == NETDEV_DOWN) sel_netif_kill(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, err; if (!selinux_enabled) 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); err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET, SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0); if (err) panic("avc_add_callback() failed, error %d\n", err); return err; } __initcall(sel_netif_init);