1 /* 2 * Spanning tree protocol; generic parts 3 * Linux ethernet bridge 4 * 5 * Authors: 6 * Lennert Buytenhek <buytenh@gnu.org> 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 11 * 2 of the License, or (at your option) any later version. 12 */ 13 #include <linux/kernel.h> 14 #include <linux/rculist.h> 15 16 #include "br_private.h" 17 #include "br_private_stp.h" 18 19 /* since time values in bpdu are in jiffies and then scaled (1/256) 20 * before sending, make sure that is at least one STP tick. 21 */ 22 #define MESSAGE_AGE_INCR ((HZ / 256) + 1) 23 24 static const char *const br_port_state_names[] = { 25 [BR_STATE_DISABLED] = "disabled", 26 [BR_STATE_LISTENING] = "listening", 27 [BR_STATE_LEARNING] = "learning", 28 [BR_STATE_FORWARDING] = "forwarding", 29 [BR_STATE_BLOCKING] = "blocking", 30 }; 31 32 void br_log_state(const struct net_bridge_port *p) 33 { 34 br_info(p->br, "port %u(%s) entered %s state\n", 35 (unsigned int) p->port_no, p->dev->name, 36 br_port_state_names[p->state]); 37 } 38 39 /* called under bridge lock */ 40 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no) 41 { 42 struct net_bridge_port *p; 43 44 list_for_each_entry_rcu(p, &br->port_list, list) { 45 if (p->port_no == port_no) 46 return p; 47 } 48 49 return NULL; 50 } 51 52 /* called under bridge lock */ 53 static int br_should_become_root_port(const struct net_bridge_port *p, 54 u16 root_port) 55 { 56 struct net_bridge *br; 57 struct net_bridge_port *rp; 58 int t; 59 60 br = p->br; 61 if (p->state == BR_STATE_DISABLED || 62 br_is_designated_port(p)) 63 return 0; 64 65 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0) 66 return 0; 67 68 if (!root_port) 69 return 1; 70 71 rp = br_get_port(br, root_port); 72 73 t = memcmp(&p->designated_root, &rp->designated_root, 8); 74 if (t < 0) 75 return 1; 76 else if (t > 0) 77 return 0; 78 79 if (p->designated_cost + p->path_cost < 80 rp->designated_cost + rp->path_cost) 81 return 1; 82 else if (p->designated_cost + p->path_cost > 83 rp->designated_cost + rp->path_cost) 84 return 0; 85 86 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8); 87 if (t < 0) 88 return 1; 89 else if (t > 0) 90 return 0; 91 92 if (p->designated_port < rp->designated_port) 93 return 1; 94 else if (p->designated_port > rp->designated_port) 95 return 0; 96 97 if (p->port_id < rp->port_id) 98 return 1; 99 100 return 0; 101 } 102 103 /* called under bridge lock */ 104 static void br_root_selection(struct net_bridge *br) 105 { 106 struct net_bridge_port *p; 107 u16 root_port = 0; 108 109 list_for_each_entry(p, &br->port_list, list) { 110 if (br_should_become_root_port(p, root_port)) 111 root_port = p->port_no; 112 } 113 114 br->root_port = root_port; 115 116 if (!root_port) { 117 br->designated_root = br->bridge_id; 118 br->root_path_cost = 0; 119 } else { 120 p = br_get_port(br, root_port); 121 br->designated_root = p->designated_root; 122 br->root_path_cost = p->designated_cost + p->path_cost; 123 } 124 } 125 126 /* called under bridge lock */ 127 void br_become_root_bridge(struct net_bridge *br) 128 { 129 br->max_age = br->bridge_max_age; 130 br->hello_time = br->bridge_hello_time; 131 br->forward_delay = br->bridge_forward_delay; 132 br_topology_change_detection(br); 133 del_timer(&br->tcn_timer); 134 135 if (br->dev->flags & IFF_UP) { 136 br_config_bpdu_generation(br); 137 mod_timer(&br->hello_timer, jiffies + br->hello_time); 138 } 139 } 140 141 /* called under bridge lock */ 142 void br_transmit_config(struct net_bridge_port *p) 143 { 144 struct br_config_bpdu bpdu; 145 struct net_bridge *br; 146 147 if (timer_pending(&p->hold_timer)) { 148 p->config_pending = 1; 149 return; 150 } 151 152 br = p->br; 153 154 bpdu.topology_change = br->topology_change; 155 bpdu.topology_change_ack = p->topology_change_ack; 156 bpdu.root = br->designated_root; 157 bpdu.root_path_cost = br->root_path_cost; 158 bpdu.bridge_id = br->bridge_id; 159 bpdu.port_id = p->port_id; 160 if (br_is_root_bridge(br)) 161 bpdu.message_age = 0; 162 else { 163 struct net_bridge_port *root 164 = br_get_port(br, br->root_port); 165 bpdu.message_age = (jiffies - root->designated_age) 166 + MESSAGE_AGE_INCR; 167 } 168 bpdu.max_age = br->max_age; 169 bpdu.hello_time = br->hello_time; 170 bpdu.forward_delay = br->forward_delay; 171 172 if (bpdu.message_age < br->max_age) { 173 br_send_config_bpdu(p, &bpdu); 174 p->topology_change_ack = 0; 175 p->config_pending = 0; 176 mod_timer(&p->hold_timer, 177 round_jiffies(jiffies + BR_HOLD_TIME)); 178 } 179 } 180 181 /* called under bridge lock */ 182 static void br_record_config_information(struct net_bridge_port *p, 183 const struct br_config_bpdu *bpdu) 184 { 185 p->designated_root = bpdu->root; 186 p->designated_cost = bpdu->root_path_cost; 187 p->designated_bridge = bpdu->bridge_id; 188 p->designated_port = bpdu->port_id; 189 p->designated_age = jiffies - bpdu->message_age; 190 191 mod_timer(&p->message_age_timer, jiffies 192 + (p->br->max_age - bpdu->message_age)); 193 } 194 195 /* called under bridge lock */ 196 static void br_record_config_timeout_values(struct net_bridge *br, 197 const struct br_config_bpdu *bpdu) 198 { 199 br->max_age = bpdu->max_age; 200 br->hello_time = bpdu->hello_time; 201 br->forward_delay = bpdu->forward_delay; 202 br->topology_change = bpdu->topology_change; 203 } 204 205 /* called under bridge lock */ 206 void br_transmit_tcn(struct net_bridge *br) 207 { 208 br_send_tcn_bpdu(br_get_port(br, br->root_port)); 209 } 210 211 /* called under bridge lock */ 212 static int br_should_become_designated_port(const struct net_bridge_port *p) 213 { 214 struct net_bridge *br; 215 int t; 216 217 br = p->br; 218 if (br_is_designated_port(p)) 219 return 1; 220 221 if (memcmp(&p->designated_root, &br->designated_root, 8)) 222 return 1; 223 224 if (br->root_path_cost < p->designated_cost) 225 return 1; 226 else if (br->root_path_cost > p->designated_cost) 227 return 0; 228 229 t = memcmp(&br->bridge_id, &p->designated_bridge, 8); 230 if (t < 0) 231 return 1; 232 else if (t > 0) 233 return 0; 234 235 if (p->port_id < p->designated_port) 236 return 1; 237 238 return 0; 239 } 240 241 /* called under bridge lock */ 242 static void br_designated_port_selection(struct net_bridge *br) 243 { 244 struct net_bridge_port *p; 245 246 list_for_each_entry(p, &br->port_list, list) { 247 if (p->state != BR_STATE_DISABLED && 248 br_should_become_designated_port(p)) 249 br_become_designated_port(p); 250 251 } 252 } 253 254 /* called under bridge lock */ 255 static int br_supersedes_port_info(const struct net_bridge_port *p, 256 const struct br_config_bpdu *bpdu) 257 { 258 int t; 259 260 t = memcmp(&bpdu->root, &p->designated_root, 8); 261 if (t < 0) 262 return 1; 263 else if (t > 0) 264 return 0; 265 266 if (bpdu->root_path_cost < p->designated_cost) 267 return 1; 268 else if (bpdu->root_path_cost > p->designated_cost) 269 return 0; 270 271 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8); 272 if (t < 0) 273 return 1; 274 else if (t > 0) 275 return 0; 276 277 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8)) 278 return 1; 279 280 if (bpdu->port_id <= p->designated_port) 281 return 1; 282 283 return 0; 284 } 285 286 /* called under bridge lock */ 287 static void br_topology_change_acknowledged(struct net_bridge *br) 288 { 289 br->topology_change_detected = 0; 290 del_timer(&br->tcn_timer); 291 } 292 293 /* called under bridge lock */ 294 void br_topology_change_detection(struct net_bridge *br) 295 { 296 int isroot = br_is_root_bridge(br); 297 298 if (br->stp_enabled != BR_KERNEL_STP) 299 return; 300 301 br_info(br, "topology change detected, %s\n", 302 isroot ? "propagating" : "sending tcn bpdu"); 303 304 if (isroot) { 305 br->topology_change = 1; 306 mod_timer(&br->topology_change_timer, jiffies 307 + br->bridge_forward_delay + br->bridge_max_age); 308 } else if (!br->topology_change_detected) { 309 br_transmit_tcn(br); 310 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time); 311 } 312 313 br->topology_change_detected = 1; 314 } 315 316 /* called under bridge lock */ 317 void br_config_bpdu_generation(struct net_bridge *br) 318 { 319 struct net_bridge_port *p; 320 321 list_for_each_entry(p, &br->port_list, list) { 322 if (p->state != BR_STATE_DISABLED && 323 br_is_designated_port(p)) 324 br_transmit_config(p); 325 } 326 } 327 328 /* called under bridge lock */ 329 static void br_reply(struct net_bridge_port *p) 330 { 331 br_transmit_config(p); 332 } 333 334 /* called under bridge lock */ 335 void br_configuration_update(struct net_bridge *br) 336 { 337 br_root_selection(br); 338 br_designated_port_selection(br); 339 } 340 341 /* called under bridge lock */ 342 void br_become_designated_port(struct net_bridge_port *p) 343 { 344 struct net_bridge *br; 345 346 br = p->br; 347 p->designated_root = br->designated_root; 348 p->designated_cost = br->root_path_cost; 349 p->designated_bridge = br->bridge_id; 350 p->designated_port = p->port_id; 351 } 352 353 354 /* called under bridge lock */ 355 static void br_make_blocking(struct net_bridge_port *p) 356 { 357 if (p->state != BR_STATE_DISABLED && 358 p->state != BR_STATE_BLOCKING) { 359 if (p->state == BR_STATE_FORWARDING || 360 p->state == BR_STATE_LEARNING) 361 br_topology_change_detection(p->br); 362 363 p->state = BR_STATE_BLOCKING; 364 br_log_state(p); 365 br_ifinfo_notify(RTM_NEWLINK, p); 366 367 del_timer(&p->forward_delay_timer); 368 } 369 } 370 371 /* called under bridge lock */ 372 static void br_make_forwarding(struct net_bridge_port *p) 373 { 374 struct net_bridge *br = p->br; 375 376 if (p->state != BR_STATE_BLOCKING) 377 return; 378 379 if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) { 380 p->state = BR_STATE_FORWARDING; 381 br_topology_change_detection(br); 382 del_timer(&p->forward_delay_timer); 383 } else if (br->stp_enabled == BR_KERNEL_STP) 384 p->state = BR_STATE_LISTENING; 385 else 386 p->state = BR_STATE_LEARNING; 387 388 br_multicast_enable_port(p); 389 br_log_state(p); 390 br_ifinfo_notify(RTM_NEWLINK, p); 391 392 if (br->forward_delay != 0) 393 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); 394 } 395 396 /* called under bridge lock */ 397 void br_port_state_selection(struct net_bridge *br) 398 { 399 struct net_bridge_port *p; 400 unsigned int liveports = 0; 401 402 list_for_each_entry(p, &br->port_list, list) { 403 if (p->state == BR_STATE_DISABLED) 404 continue; 405 406 /* Don't change port states if userspace is handling STP */ 407 if (br->stp_enabled != BR_USER_STP) { 408 if (p->port_no == br->root_port) { 409 p->config_pending = 0; 410 p->topology_change_ack = 0; 411 br_make_forwarding(p); 412 } else if (br_is_designated_port(p)) { 413 del_timer(&p->message_age_timer); 414 br_make_forwarding(p); 415 } else { 416 p->config_pending = 0; 417 p->topology_change_ack = 0; 418 br_make_blocking(p); 419 } 420 } 421 422 if (p->state == BR_STATE_FORWARDING) 423 ++liveports; 424 } 425 426 if (liveports == 0) 427 netif_carrier_off(br->dev); 428 else 429 netif_carrier_on(br->dev); 430 } 431 432 /* called under bridge lock */ 433 static void br_topology_change_acknowledge(struct net_bridge_port *p) 434 { 435 p->topology_change_ack = 1; 436 br_transmit_config(p); 437 } 438 439 /* called under bridge lock */ 440 void br_received_config_bpdu(struct net_bridge_port *p, 441 const struct br_config_bpdu *bpdu) 442 { 443 struct net_bridge *br; 444 int was_root; 445 446 br = p->br; 447 was_root = br_is_root_bridge(br); 448 449 if (br_supersedes_port_info(p, bpdu)) { 450 br_record_config_information(p, bpdu); 451 br_configuration_update(br); 452 br_port_state_selection(br); 453 454 if (!br_is_root_bridge(br) && was_root) { 455 del_timer(&br->hello_timer); 456 if (br->topology_change_detected) { 457 del_timer(&br->topology_change_timer); 458 br_transmit_tcn(br); 459 460 mod_timer(&br->tcn_timer, 461 jiffies + br->bridge_hello_time); 462 } 463 } 464 465 if (p->port_no == br->root_port) { 466 br_record_config_timeout_values(br, bpdu); 467 br_config_bpdu_generation(br); 468 if (bpdu->topology_change_ack) 469 br_topology_change_acknowledged(br); 470 } 471 } else if (br_is_designated_port(p)) { 472 br_reply(p); 473 } 474 } 475 476 /* called under bridge lock */ 477 void br_received_tcn_bpdu(struct net_bridge_port *p) 478 { 479 if (br_is_designated_port(p)) { 480 br_info(p->br, "port %u(%s) received tcn bpdu\n", 481 (unsigned int) p->port_no, p->dev->name); 482 483 br_topology_change_detection(p->br); 484 br_topology_change_acknowledge(p); 485 } 486 } 487 488 /* Change bridge STP parameter */ 489 int br_set_hello_time(struct net_bridge *br, unsigned long val) 490 { 491 unsigned long t = clock_t_to_jiffies(val); 492 493 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME) 494 return -ERANGE; 495 496 spin_lock_bh(&br->lock); 497 br->bridge_hello_time = t; 498 if (br_is_root_bridge(br)) 499 br->hello_time = br->bridge_hello_time; 500 spin_unlock_bh(&br->lock); 501 return 0; 502 } 503 504 int br_set_max_age(struct net_bridge *br, unsigned long val) 505 { 506 unsigned long t = clock_t_to_jiffies(val); 507 508 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE) 509 return -ERANGE; 510 511 spin_lock_bh(&br->lock); 512 br->bridge_max_age = t; 513 if (br_is_root_bridge(br)) 514 br->max_age = br->bridge_max_age; 515 spin_unlock_bh(&br->lock); 516 return 0; 517 518 } 519 520 int br_set_forward_delay(struct net_bridge *br, unsigned long val) 521 { 522 unsigned long t = clock_t_to_jiffies(val); 523 524 if (br->stp_enabled != BR_NO_STP && 525 (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY)) 526 return -ERANGE; 527 528 spin_lock_bh(&br->lock); 529 br->bridge_forward_delay = t; 530 if (br_is_root_bridge(br)) 531 br->forward_delay = br->bridge_forward_delay; 532 spin_unlock_bh(&br->lock); 533 return 0; 534 } 535