1 /* 2 * Forwarding database 3 * Linux ethernet bridge 4 * 5 * Authors: 6 * Lennert Buytenhek <buytenh@gnu.org> 7 * 8 * $Id: br_fdb.c,v 1.6 2002/01/17 00:57:07 davem Exp $ 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 */ 15 16 #include <linux/kernel.h> 17 #include <linux/init.h> 18 #include <linux/spinlock.h> 19 #include <linux/times.h> 20 #include <linux/netdevice.h> 21 #include <linux/etherdevice.h> 22 #include <linux/jhash.h> 23 #include <linux/random.h> 24 #include <asm/atomic.h> 25 #include <asm/unaligned.h> 26 #include "br_private.h" 27 28 static struct kmem_cache *br_fdb_cache __read_mostly; 29 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source, 30 const unsigned char *addr); 31 32 static u32 fdb_salt __read_mostly; 33 34 int __init br_fdb_init(void) 35 { 36 br_fdb_cache = kmem_cache_create("bridge_fdb_cache", 37 sizeof(struct net_bridge_fdb_entry), 38 0, 39 SLAB_HWCACHE_ALIGN, NULL, NULL); 40 if (!br_fdb_cache) 41 return -ENOMEM; 42 43 get_random_bytes(&fdb_salt, sizeof(fdb_salt)); 44 return 0; 45 } 46 47 void __exit br_fdb_fini(void) 48 { 49 kmem_cache_destroy(br_fdb_cache); 50 } 51 52 53 /* if topology_changing then use forward_delay (default 15 sec) 54 * otherwise keep longer (default 5 minutes) 55 */ 56 static inline unsigned long hold_time(const struct net_bridge *br) 57 { 58 return br->topology_change ? br->forward_delay : br->ageing_time; 59 } 60 61 static inline int has_expired(const struct net_bridge *br, 62 const struct net_bridge_fdb_entry *fdb) 63 { 64 return !fdb->is_static 65 && time_before_eq(fdb->ageing_timer + hold_time(br), jiffies); 66 } 67 68 static inline int br_mac_hash(const unsigned char *mac) 69 { 70 /* use 1 byte of OUI cnd 3 bytes of NIC */ 71 u32 key = get_unaligned((u32 *)(mac + 2)); 72 return jhash_1word(key, fdb_salt) & (BR_HASH_SIZE - 1); 73 } 74 75 static inline void fdb_delete(struct net_bridge_fdb_entry *f) 76 { 77 hlist_del_rcu(&f->hlist); 78 br_fdb_put(f); 79 } 80 81 void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr) 82 { 83 struct net_bridge *br = p->br; 84 int i; 85 86 spin_lock_bh(&br->hash_lock); 87 88 /* Search all chains since old address/hash is unknown */ 89 for (i = 0; i < BR_HASH_SIZE; i++) { 90 struct hlist_node *h; 91 hlist_for_each(h, &br->hash[i]) { 92 struct net_bridge_fdb_entry *f; 93 94 f = hlist_entry(h, struct net_bridge_fdb_entry, hlist); 95 if (f->dst == p && f->is_local) { 96 /* maybe another port has same hw addr? */ 97 struct net_bridge_port *op; 98 list_for_each_entry(op, &br->port_list, list) { 99 if (op != p && 100 !compare_ether_addr(op->dev->dev_addr, 101 f->addr.addr)) { 102 f->dst = op; 103 goto insert; 104 } 105 } 106 107 /* delete old one */ 108 fdb_delete(f); 109 goto insert; 110 } 111 } 112 } 113 insert: 114 /* insert new address, may fail if invalid address or dup. */ 115 fdb_insert(br, p, newaddr); 116 117 spin_unlock_bh(&br->hash_lock); 118 } 119 120 void br_fdb_cleanup(unsigned long _data) 121 { 122 struct net_bridge *br = (struct net_bridge *)_data; 123 unsigned long delay = hold_time(br); 124 int i; 125 126 spin_lock_bh(&br->hash_lock); 127 for (i = 0; i < BR_HASH_SIZE; i++) { 128 struct net_bridge_fdb_entry *f; 129 struct hlist_node *h, *n; 130 131 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) { 132 if (!f->is_static && 133 time_before_eq(f->ageing_timer + delay, jiffies)) 134 fdb_delete(f); 135 } 136 } 137 spin_unlock_bh(&br->hash_lock); 138 139 mod_timer(&br->gc_timer, jiffies + HZ/10); 140 } 141 142 /* Completely flush all dynamic entries in forwarding database.*/ 143 void br_fdb_flush(struct net_bridge *br) 144 { 145 int i; 146 147 spin_lock_bh(&br->hash_lock); 148 for (i = 0; i < BR_HASH_SIZE; i++) { 149 struct net_bridge_fdb_entry *f; 150 struct hlist_node *h, *n; 151 hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) { 152 if (!f->is_static) 153 fdb_delete(f); 154 } 155 } 156 spin_unlock_bh(&br->hash_lock); 157 } 158 159 /* Flush all entries refering to a specific port. 160 * if do_all is set also flush static entries 161 */ 162 void br_fdb_delete_by_port(struct net_bridge *br, 163 const struct net_bridge_port *p, 164 int do_all) 165 { 166 int i; 167 168 spin_lock_bh(&br->hash_lock); 169 for (i = 0; i < BR_HASH_SIZE; i++) { 170 struct hlist_node *h, *g; 171 172 hlist_for_each_safe(h, g, &br->hash[i]) { 173 struct net_bridge_fdb_entry *f 174 = hlist_entry(h, struct net_bridge_fdb_entry, hlist); 175 if (f->dst != p) 176 continue; 177 178 if (f->is_static && !do_all) 179 continue; 180 /* 181 * if multiple ports all have the same device address 182 * then when one port is deleted, assign 183 * the local entry to other port 184 */ 185 if (f->is_local) { 186 struct net_bridge_port *op; 187 list_for_each_entry(op, &br->port_list, list) { 188 if (op != p && 189 !compare_ether_addr(op->dev->dev_addr, 190 f->addr.addr)) { 191 f->dst = op; 192 goto skip_delete; 193 } 194 } 195 } 196 197 fdb_delete(f); 198 skip_delete: ; 199 } 200 } 201 spin_unlock_bh(&br->hash_lock); 202 } 203 204 /* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */ 205 struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br, 206 const unsigned char *addr) 207 { 208 struct hlist_node *h; 209 struct net_bridge_fdb_entry *fdb; 210 211 hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) { 212 if (!compare_ether_addr(fdb->addr.addr, addr)) { 213 if (unlikely(has_expired(br, fdb))) 214 break; 215 return fdb; 216 } 217 } 218 219 return NULL; 220 } 221 222 /* Interface used by ATM hook that keeps a ref count */ 223 struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br, 224 unsigned char *addr) 225 { 226 struct net_bridge_fdb_entry *fdb; 227 228 rcu_read_lock(); 229 fdb = __br_fdb_get(br, addr); 230 if (fdb && !atomic_inc_not_zero(&fdb->use_count)) 231 fdb = NULL; 232 rcu_read_unlock(); 233 return fdb; 234 } 235 236 static void fdb_rcu_free(struct rcu_head *head) 237 { 238 struct net_bridge_fdb_entry *ent 239 = container_of(head, struct net_bridge_fdb_entry, rcu); 240 kmem_cache_free(br_fdb_cache, ent); 241 } 242 243 /* Set entry up for deletion with RCU */ 244 void br_fdb_put(struct net_bridge_fdb_entry *ent) 245 { 246 if (atomic_dec_and_test(&ent->use_count)) 247 call_rcu(&ent->rcu, fdb_rcu_free); 248 } 249 250 /* 251 * Fill buffer with forwarding table records in 252 * the API format. 253 */ 254 int br_fdb_fillbuf(struct net_bridge *br, void *buf, 255 unsigned long maxnum, unsigned long skip) 256 { 257 struct __fdb_entry *fe = buf; 258 int i, num = 0; 259 struct hlist_node *h; 260 struct net_bridge_fdb_entry *f; 261 262 memset(buf, 0, maxnum*sizeof(struct __fdb_entry)); 263 264 rcu_read_lock(); 265 for (i = 0; i < BR_HASH_SIZE; i++) { 266 hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) { 267 if (num >= maxnum) 268 goto out; 269 270 if (has_expired(br, f)) 271 continue; 272 273 if (skip) { 274 --skip; 275 continue; 276 } 277 278 /* convert from internal format to API */ 279 memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN); 280 fe->port_no = f->dst->port_no; 281 fe->is_local = f->is_local; 282 if (!f->is_static) 283 fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer); 284 ++fe; 285 ++num; 286 } 287 } 288 289 out: 290 rcu_read_unlock(); 291 292 return num; 293 } 294 295 static inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head, 296 const unsigned char *addr) 297 { 298 struct hlist_node *h; 299 struct net_bridge_fdb_entry *fdb; 300 301 hlist_for_each_entry_rcu(fdb, h, head, hlist) { 302 if (!compare_ether_addr(fdb->addr.addr, addr)) 303 return fdb; 304 } 305 return NULL; 306 } 307 308 static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head, 309 struct net_bridge_port *source, 310 const unsigned char *addr, 311 int is_local) 312 { 313 struct net_bridge_fdb_entry *fdb; 314 315 fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC); 316 if (fdb) { 317 memcpy(fdb->addr.addr, addr, ETH_ALEN); 318 atomic_set(&fdb->use_count, 1); 319 hlist_add_head_rcu(&fdb->hlist, head); 320 321 fdb->dst = source; 322 fdb->is_local = is_local; 323 fdb->is_static = is_local; 324 fdb->ageing_timer = jiffies; 325 } 326 return fdb; 327 } 328 329 static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source, 330 const unsigned char *addr) 331 { 332 struct hlist_head *head = &br->hash[br_mac_hash(addr)]; 333 struct net_bridge_fdb_entry *fdb; 334 335 if (!is_valid_ether_addr(addr)) 336 return -EINVAL; 337 338 fdb = fdb_find(head, addr); 339 if (fdb) { 340 /* it is okay to have multiple ports with same 341 * address, just use the first one. 342 */ 343 if (fdb->is_local) 344 return 0; 345 346 printk(KERN_WARNING "%s adding interface with same address " 347 "as a received packet\n", 348 source->dev->name); 349 fdb_delete(fdb); 350 } 351 352 if (!fdb_create(head, source, addr, 1)) 353 return -ENOMEM; 354 355 return 0; 356 } 357 358 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source, 359 const unsigned char *addr) 360 { 361 int ret; 362 363 spin_lock_bh(&br->hash_lock); 364 ret = fdb_insert(br, source, addr); 365 spin_unlock_bh(&br->hash_lock); 366 return ret; 367 } 368 369 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, 370 const unsigned char *addr) 371 { 372 struct hlist_head *head = &br->hash[br_mac_hash(addr)]; 373 struct net_bridge_fdb_entry *fdb; 374 375 /* some users want to always flood. */ 376 if (hold_time(br) == 0) 377 return; 378 379 fdb = fdb_find(head, addr); 380 if (likely(fdb)) { 381 /* attempt to update an entry for a local interface */ 382 if (unlikely(fdb->is_local)) { 383 if (net_ratelimit()) 384 printk(KERN_WARNING "%s: received packet with " 385 " own address as source address\n", 386 source->dev->name); 387 } else { 388 /* fastpath: update of existing entry */ 389 fdb->dst = source; 390 fdb->ageing_timer = jiffies; 391 } 392 } else { 393 spin_lock(&br->hash_lock); 394 if (!fdb_find(head, addr)) 395 fdb_create(head, source, addr, 0); 396 /* else we lose race and someone else inserts 397 * it first, don't bother updating 398 */ 399 spin_unlock(&br->hash_lock); 400 } 401 } 402