1 /* 2 * Network interface table. 3 * 4 * Network interfaces (devices) do not have a security field, so we 5 * maintain a table associating each interface with a SID. 6 * 7 * Author: James Morris <jmorris@redhat.com> 8 * 9 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com> 10 * Copyright (C) 2007 Hewlett-Packard Development Company, L.P. 11 * Paul Moore <paul.moore@hp.com> 12 * 13 * This program is free software; you can redistribute it and/or modify 14 * it under the terms of the GNU General Public License version 2, 15 * as published by the Free Software Foundation. 16 */ 17 #include <linux/init.h> 18 #include <linux/types.h> 19 #include <linux/slab.h> 20 #include <linux/stddef.h> 21 #include <linux/kernel.h> 22 #include <linux/list.h> 23 #include <linux/notifier.h> 24 #include <linux/netdevice.h> 25 #include <linux/rcupdate.h> 26 #include <net/net_namespace.h> 27 28 #include "security.h" 29 #include "objsec.h" 30 #include "netif.h" 31 32 #define SEL_NETIF_HASH_SIZE 64 33 #define SEL_NETIF_HASH_MAX 1024 34 35 struct sel_netif { 36 struct list_head list; 37 struct netif_security_struct nsec; 38 struct rcu_head rcu_head; 39 }; 40 41 static u32 sel_netif_total; 42 static LIST_HEAD(sel_netif_list); 43 static DEFINE_SPINLOCK(sel_netif_lock); 44 static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE]; 45 46 /** 47 * sel_netif_hashfn - Hashing function for the interface table 48 * @ifindex: the network interface 49 * 50 * Description: 51 * This is the hashing function for the network interface table, it returns the 52 * bucket number for the given interface. 53 * 54 */ 55 static inline u32 sel_netif_hashfn(int ifindex) 56 { 57 return (ifindex & (SEL_NETIF_HASH_SIZE - 1)); 58 } 59 60 /** 61 * sel_netif_find - Search for an interface record 62 * @ifindex: the network interface 63 * 64 * Description: 65 * Search the network interface table and return the record matching @ifindex. 66 * If an entry can not be found in the table return NULL. 67 * 68 */ 69 static inline struct sel_netif *sel_netif_find(int ifindex) 70 { 71 int idx = sel_netif_hashfn(ifindex); 72 struct sel_netif *netif; 73 74 list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list) 75 /* all of the devices should normally fit in the hash, so we 76 * optimize for that case */ 77 if (likely(netif->nsec.ifindex == ifindex)) 78 return netif; 79 80 return NULL; 81 } 82 83 /** 84 * sel_netif_insert - Insert a new interface into the table 85 * @netif: the new interface record 86 * 87 * Description: 88 * Add a new interface record to the network interface hash table. Returns 89 * zero on success, negative values on failure. 90 * 91 */ 92 static int sel_netif_insert(struct sel_netif *netif) 93 { 94 int idx; 95 96 if (sel_netif_total >= SEL_NETIF_HASH_MAX) 97 return -ENOSPC; 98 99 idx = sel_netif_hashfn(netif->nsec.ifindex); 100 list_add_rcu(&netif->list, &sel_netif_hash[idx]); 101 sel_netif_total++; 102 103 return 0; 104 } 105 106 /** 107 * sel_netif_destroy - Remove an interface record from the table 108 * @netif: the existing interface record 109 * 110 * Description: 111 * Remove an existing interface record from the network interface table. 112 * 113 */ 114 static void sel_netif_destroy(struct sel_netif *netif) 115 { 116 list_del_rcu(&netif->list); 117 sel_netif_total--; 118 kfree_rcu(netif, rcu_head); 119 } 120 121 /** 122 * sel_netif_sid_slow - Lookup the SID of a network interface using the policy 123 * @ifindex: the network interface 124 * @sid: interface SID 125 * 126 * Description: 127 * This function determines the SID of a network interface by quering the 128 * security policy. The result is added to the network interface table to 129 * speedup future queries. Returns zero on success, negative values on 130 * failure. 131 * 132 */ 133 static int sel_netif_sid_slow(int ifindex, u32 *sid) 134 { 135 int ret; 136 struct sel_netif *netif; 137 struct sel_netif *new = NULL; 138 struct net_device *dev; 139 140 /* NOTE: we always use init's network namespace since we don't 141 * currently support containers */ 142 143 dev = dev_get_by_index(&init_net, ifindex); 144 if (unlikely(dev == NULL)) { 145 printk(KERN_WARNING 146 "SELinux: failure in sel_netif_sid_slow()," 147 " invalid network interface (%d)\n", ifindex); 148 return -ENOENT; 149 } 150 151 spin_lock_bh(&sel_netif_lock); 152 netif = sel_netif_find(ifindex); 153 if (netif != NULL) { 154 *sid = netif->nsec.sid; 155 ret = 0; 156 goto out; 157 } 158 new = kzalloc(sizeof(*new), GFP_ATOMIC); 159 if (new == NULL) { 160 ret = -ENOMEM; 161 goto out; 162 } 163 ret = security_netif_sid(dev->name, &new->nsec.sid); 164 if (ret != 0) 165 goto out; 166 new->nsec.ifindex = ifindex; 167 ret = sel_netif_insert(new); 168 if (ret != 0) 169 goto out; 170 *sid = new->nsec.sid; 171 172 out: 173 spin_unlock_bh(&sel_netif_lock); 174 dev_put(dev); 175 if (unlikely(ret)) { 176 printk(KERN_WARNING 177 "SELinux: failure in sel_netif_sid_slow()," 178 " unable to determine network interface label (%d)\n", 179 ifindex); 180 kfree(new); 181 } 182 return ret; 183 } 184 185 /** 186 * sel_netif_sid - Lookup the SID of a network interface 187 * @ifindex: the network interface 188 * @sid: interface SID 189 * 190 * Description: 191 * This function determines the SID of a network interface using the fastest 192 * method possible. First the interface table is queried, but if an entry 193 * can't be found then the policy is queried and the result is added to the 194 * table to speedup future queries. Returns zero on success, negative values 195 * on failure. 196 * 197 */ 198 int sel_netif_sid(int ifindex, u32 *sid) 199 { 200 struct sel_netif *netif; 201 202 rcu_read_lock(); 203 netif = sel_netif_find(ifindex); 204 if (likely(netif != NULL)) { 205 *sid = netif->nsec.sid; 206 rcu_read_unlock(); 207 return 0; 208 } 209 rcu_read_unlock(); 210 211 return sel_netif_sid_slow(ifindex, sid); 212 } 213 214 /** 215 * sel_netif_kill - Remove an entry from the network interface table 216 * @ifindex: the network interface 217 * 218 * Description: 219 * This function removes the entry matching @ifindex from the network interface 220 * table if it exists. 221 * 222 */ 223 static void sel_netif_kill(int ifindex) 224 { 225 struct sel_netif *netif; 226 227 rcu_read_lock(); 228 spin_lock_bh(&sel_netif_lock); 229 netif = sel_netif_find(ifindex); 230 if (netif) 231 sel_netif_destroy(netif); 232 spin_unlock_bh(&sel_netif_lock); 233 rcu_read_unlock(); 234 } 235 236 /** 237 * sel_netif_flush - Flush the entire network interface table 238 * 239 * Description: 240 * Remove all entries from the network interface table. 241 * 242 */ 243 static void sel_netif_flush(void) 244 { 245 int idx; 246 struct sel_netif *netif; 247 248 spin_lock_bh(&sel_netif_lock); 249 for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++) 250 list_for_each_entry(netif, &sel_netif_hash[idx], list) 251 sel_netif_destroy(netif); 252 spin_unlock_bh(&sel_netif_lock); 253 } 254 255 static int sel_netif_avc_callback(u32 event, u32 ssid, u32 tsid, 256 u16 class, u32 perms, u32 *retained) 257 { 258 if (event == AVC_CALLBACK_RESET) { 259 sel_netif_flush(); 260 synchronize_net(); 261 } 262 return 0; 263 } 264 265 static int sel_netif_netdev_notifier_handler(struct notifier_block *this, 266 unsigned long event, void *ptr) 267 { 268 struct net_device *dev = ptr; 269 270 if (dev_net(dev) != &init_net) 271 return NOTIFY_DONE; 272 273 if (event == NETDEV_DOWN) 274 sel_netif_kill(dev->ifindex); 275 276 return NOTIFY_DONE; 277 } 278 279 static struct notifier_block sel_netif_netdev_notifier = { 280 .notifier_call = sel_netif_netdev_notifier_handler, 281 }; 282 283 static __init int sel_netif_init(void) 284 { 285 int i, err; 286 287 if (!selinux_enabled) 288 return 0; 289 290 for (i = 0; i < SEL_NETIF_HASH_SIZE; i++) 291 INIT_LIST_HEAD(&sel_netif_hash[i]); 292 293 register_netdevice_notifier(&sel_netif_netdev_notifier); 294 295 err = avc_add_callback(sel_netif_avc_callback, AVC_CALLBACK_RESET, 296 SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0); 297 if (err) 298 panic("avc_add_callback() failed, error %d\n", err); 299 300 return err; 301 } 302 303 __initcall(sel_netif_init); 304 305