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 #include <net/switchdev.h> 16 17 #include "br_private.h" 18 #include "br_private_stp.h" 19 20 /* since time values in bpdu are in jiffies and then scaled (1/256) 21 * before sending, make sure that is at least one STP tick. 22 */ 23 #define MESSAGE_AGE_INCR ((HZ / 256) + 1) 24 25 static const char *const br_port_state_names[] = { 26 [BR_STATE_DISABLED] = "disabled", 27 [BR_STATE_LISTENING] = "listening", 28 [BR_STATE_LEARNING] = "learning", 29 [BR_STATE_FORWARDING] = "forwarding", 30 [BR_STATE_BLOCKING] = "blocking", 31 }; 32 33 void br_set_state(struct net_bridge_port *p, unsigned int state) 34 { 35 struct switchdev_attr attr = { 36 .orig_dev = p->dev, 37 .id = SWITCHDEV_ATTR_ID_PORT_STP_STATE, 38 .flags = SWITCHDEV_F_DEFER, 39 .u.stp_state = state, 40 }; 41 int err; 42 43 p->state = state; 44 err = switchdev_port_attr_set(p->dev, &attr); 45 if (err && err != -EOPNOTSUPP) 46 br_warn(p->br, "error setting offload STP state on port %u(%s)\n", 47 (unsigned int) p->port_no, p->dev->name); 48 else 49 br_info(p->br, "port %u(%s) entered %s state\n", 50 (unsigned int) p->port_no, p->dev->name, 51 br_port_state_names[p->state]); 52 } 53 54 /* called under bridge lock */ 55 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no) 56 { 57 struct net_bridge_port *p; 58 59 list_for_each_entry_rcu(p, &br->port_list, list) { 60 if (p->port_no == port_no) 61 return p; 62 } 63 64 return NULL; 65 } 66 67 /* called under bridge lock */ 68 static int br_should_become_root_port(const struct net_bridge_port *p, 69 u16 root_port) 70 { 71 struct net_bridge *br; 72 struct net_bridge_port *rp; 73 int t; 74 75 br = p->br; 76 if (p->state == BR_STATE_DISABLED || 77 br_is_designated_port(p)) 78 return 0; 79 80 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0) 81 return 0; 82 83 if (!root_port) 84 return 1; 85 86 rp = br_get_port(br, root_port); 87 88 t = memcmp(&p->designated_root, &rp->designated_root, 8); 89 if (t < 0) 90 return 1; 91 else if (t > 0) 92 return 0; 93 94 if (p->designated_cost + p->path_cost < 95 rp->designated_cost + rp->path_cost) 96 return 1; 97 else if (p->designated_cost + p->path_cost > 98 rp->designated_cost + rp->path_cost) 99 return 0; 100 101 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8); 102 if (t < 0) 103 return 1; 104 else if (t > 0) 105 return 0; 106 107 if (p->designated_port < rp->designated_port) 108 return 1; 109 else if (p->designated_port > rp->designated_port) 110 return 0; 111 112 if (p->port_id < rp->port_id) 113 return 1; 114 115 return 0; 116 } 117 118 static void br_root_port_block(const struct net_bridge *br, 119 struct net_bridge_port *p) 120 { 121 122 br_notice(br, "port %u(%s) tried to become root port (blocked)", 123 (unsigned int) p->port_no, p->dev->name); 124 125 br_set_state(p, BR_STATE_LISTENING); 126 br_ifinfo_notify(RTM_NEWLINK, p); 127 128 if (br->forward_delay > 0) 129 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); 130 } 131 132 /* called under bridge lock */ 133 static void br_root_selection(struct net_bridge *br) 134 { 135 struct net_bridge_port *p; 136 u16 root_port = 0; 137 138 list_for_each_entry(p, &br->port_list, list) { 139 if (!br_should_become_root_port(p, root_port)) 140 continue; 141 142 if (p->flags & BR_ROOT_BLOCK) 143 br_root_port_block(br, p); 144 else 145 root_port = p->port_no; 146 } 147 148 br->root_port = root_port; 149 150 if (!root_port) { 151 br->designated_root = br->bridge_id; 152 br->root_path_cost = 0; 153 } else { 154 p = br_get_port(br, root_port); 155 br->designated_root = p->designated_root; 156 br->root_path_cost = p->designated_cost + p->path_cost; 157 } 158 } 159 160 /* called under bridge lock */ 161 void br_become_root_bridge(struct net_bridge *br) 162 { 163 br->max_age = br->bridge_max_age; 164 br->hello_time = br->bridge_hello_time; 165 br->forward_delay = br->bridge_forward_delay; 166 br_topology_change_detection(br); 167 del_timer(&br->tcn_timer); 168 169 if (br->dev->flags & IFF_UP) { 170 br_config_bpdu_generation(br); 171 mod_timer(&br->hello_timer, jiffies + br->hello_time); 172 } 173 } 174 175 /* called under bridge lock */ 176 void br_transmit_config(struct net_bridge_port *p) 177 { 178 struct br_config_bpdu bpdu; 179 struct net_bridge *br; 180 181 if (timer_pending(&p->hold_timer)) { 182 p->config_pending = 1; 183 return; 184 } 185 186 br = p->br; 187 188 bpdu.topology_change = br->topology_change; 189 bpdu.topology_change_ack = p->topology_change_ack; 190 bpdu.root = br->designated_root; 191 bpdu.root_path_cost = br->root_path_cost; 192 bpdu.bridge_id = br->bridge_id; 193 bpdu.port_id = p->port_id; 194 if (br_is_root_bridge(br)) 195 bpdu.message_age = 0; 196 else { 197 struct net_bridge_port *root 198 = br_get_port(br, br->root_port); 199 bpdu.message_age = (jiffies - root->designated_age) 200 + MESSAGE_AGE_INCR; 201 } 202 bpdu.max_age = br->max_age; 203 bpdu.hello_time = br->hello_time; 204 bpdu.forward_delay = br->forward_delay; 205 206 if (bpdu.message_age < br->max_age) { 207 br_send_config_bpdu(p, &bpdu); 208 p->topology_change_ack = 0; 209 p->config_pending = 0; 210 if (p->br->stp_enabled == BR_KERNEL_STP) 211 mod_timer(&p->hold_timer, 212 round_jiffies(jiffies + BR_HOLD_TIME)); 213 } 214 } 215 216 /* called under bridge lock */ 217 static void br_record_config_information(struct net_bridge_port *p, 218 const struct br_config_bpdu *bpdu) 219 { 220 p->designated_root = bpdu->root; 221 p->designated_cost = bpdu->root_path_cost; 222 p->designated_bridge = bpdu->bridge_id; 223 p->designated_port = bpdu->port_id; 224 p->designated_age = jiffies - bpdu->message_age; 225 226 mod_timer(&p->message_age_timer, jiffies 227 + (bpdu->max_age - bpdu->message_age)); 228 } 229 230 /* called under bridge lock */ 231 static void br_record_config_timeout_values(struct net_bridge *br, 232 const struct br_config_bpdu *bpdu) 233 { 234 br->max_age = bpdu->max_age; 235 br->hello_time = bpdu->hello_time; 236 br->forward_delay = bpdu->forward_delay; 237 __br_set_topology_change(br, bpdu->topology_change); 238 } 239 240 /* called under bridge lock */ 241 void br_transmit_tcn(struct net_bridge *br) 242 { 243 struct net_bridge_port *p; 244 245 p = br_get_port(br, br->root_port); 246 if (p) 247 br_send_tcn_bpdu(p); 248 else 249 br_notice(br, "root port %u not found for topology notice\n", 250 br->root_port); 251 } 252 253 /* called under bridge lock */ 254 static int br_should_become_designated_port(const struct net_bridge_port *p) 255 { 256 struct net_bridge *br; 257 int t; 258 259 br = p->br; 260 if (br_is_designated_port(p)) 261 return 1; 262 263 if (memcmp(&p->designated_root, &br->designated_root, 8)) 264 return 1; 265 266 if (br->root_path_cost < p->designated_cost) 267 return 1; 268 else if (br->root_path_cost > p->designated_cost) 269 return 0; 270 271 t = memcmp(&br->bridge_id, &p->designated_bridge, 8); 272 if (t < 0) 273 return 1; 274 else if (t > 0) 275 return 0; 276 277 if (p->port_id < p->designated_port) 278 return 1; 279 280 return 0; 281 } 282 283 /* called under bridge lock */ 284 static void br_designated_port_selection(struct net_bridge *br) 285 { 286 struct net_bridge_port *p; 287 288 list_for_each_entry(p, &br->port_list, list) { 289 if (p->state != BR_STATE_DISABLED && 290 br_should_become_designated_port(p)) 291 br_become_designated_port(p); 292 293 } 294 } 295 296 /* called under bridge lock */ 297 static int br_supersedes_port_info(const struct net_bridge_port *p, 298 const struct br_config_bpdu *bpdu) 299 { 300 int t; 301 302 t = memcmp(&bpdu->root, &p->designated_root, 8); 303 if (t < 0) 304 return 1; 305 else if (t > 0) 306 return 0; 307 308 if (bpdu->root_path_cost < p->designated_cost) 309 return 1; 310 else if (bpdu->root_path_cost > p->designated_cost) 311 return 0; 312 313 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8); 314 if (t < 0) 315 return 1; 316 else if (t > 0) 317 return 0; 318 319 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8)) 320 return 1; 321 322 if (bpdu->port_id <= p->designated_port) 323 return 1; 324 325 return 0; 326 } 327 328 /* called under bridge lock */ 329 static void br_topology_change_acknowledged(struct net_bridge *br) 330 { 331 br->topology_change_detected = 0; 332 del_timer(&br->tcn_timer); 333 } 334 335 /* called under bridge lock */ 336 void br_topology_change_detection(struct net_bridge *br) 337 { 338 int isroot = br_is_root_bridge(br); 339 340 if (br->stp_enabled != BR_KERNEL_STP) 341 return; 342 343 br_info(br, "topology change detected, %s\n", 344 isroot ? "propagating" : "sending tcn bpdu"); 345 346 if (isroot) { 347 __br_set_topology_change(br, 1); 348 mod_timer(&br->topology_change_timer, jiffies 349 + br->bridge_forward_delay + br->bridge_max_age); 350 } else if (!br->topology_change_detected) { 351 br_transmit_tcn(br); 352 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time); 353 } 354 355 br->topology_change_detected = 1; 356 } 357 358 /* called under bridge lock */ 359 void br_config_bpdu_generation(struct net_bridge *br) 360 { 361 struct net_bridge_port *p; 362 363 list_for_each_entry(p, &br->port_list, list) { 364 if (p->state != BR_STATE_DISABLED && 365 br_is_designated_port(p)) 366 br_transmit_config(p); 367 } 368 } 369 370 /* called under bridge lock */ 371 static void br_reply(struct net_bridge_port *p) 372 { 373 br_transmit_config(p); 374 } 375 376 /* called under bridge lock */ 377 void br_configuration_update(struct net_bridge *br) 378 { 379 br_root_selection(br); 380 br_designated_port_selection(br); 381 } 382 383 /* called under bridge lock */ 384 void br_become_designated_port(struct net_bridge_port *p) 385 { 386 struct net_bridge *br; 387 388 br = p->br; 389 p->designated_root = br->designated_root; 390 p->designated_cost = br->root_path_cost; 391 p->designated_bridge = br->bridge_id; 392 p->designated_port = p->port_id; 393 } 394 395 396 /* called under bridge lock */ 397 static void br_make_blocking(struct net_bridge_port *p) 398 { 399 if (p->state != BR_STATE_DISABLED && 400 p->state != BR_STATE_BLOCKING) { 401 if (p->state == BR_STATE_FORWARDING || 402 p->state == BR_STATE_LEARNING) 403 br_topology_change_detection(p->br); 404 405 br_set_state(p, BR_STATE_BLOCKING); 406 br_ifinfo_notify(RTM_NEWLINK, p); 407 408 del_timer(&p->forward_delay_timer); 409 } 410 } 411 412 /* called under bridge lock */ 413 static void br_make_forwarding(struct net_bridge_port *p) 414 { 415 struct net_bridge *br = p->br; 416 417 if (p->state != BR_STATE_BLOCKING) 418 return; 419 420 if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) { 421 br_set_state(p, BR_STATE_FORWARDING); 422 br_topology_change_detection(br); 423 del_timer(&p->forward_delay_timer); 424 } else if (br->stp_enabled == BR_KERNEL_STP) 425 br_set_state(p, BR_STATE_LISTENING); 426 else 427 br_set_state(p, BR_STATE_LEARNING); 428 429 br_ifinfo_notify(RTM_NEWLINK, p); 430 431 if (br->forward_delay != 0) 432 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); 433 } 434 435 /* called under bridge lock */ 436 void br_port_state_selection(struct net_bridge *br) 437 { 438 struct net_bridge_port *p; 439 unsigned int liveports = 0; 440 441 list_for_each_entry(p, &br->port_list, list) { 442 if (p->state == BR_STATE_DISABLED) 443 continue; 444 445 /* Don't change port states if userspace is handling STP */ 446 if (br->stp_enabled != BR_USER_STP) { 447 if (p->port_no == br->root_port) { 448 p->config_pending = 0; 449 p->topology_change_ack = 0; 450 br_make_forwarding(p); 451 } else if (br_is_designated_port(p)) { 452 del_timer(&p->message_age_timer); 453 br_make_forwarding(p); 454 } else { 455 p->config_pending = 0; 456 p->topology_change_ack = 0; 457 br_make_blocking(p); 458 } 459 } 460 461 if (p->state != BR_STATE_BLOCKING) 462 br_multicast_enable_port(p); 463 /* Multicast is not disabled for the port when it goes in 464 * blocking state because the timers will expire and stop by 465 * themselves without sending more queries. 466 */ 467 if (p->state == BR_STATE_FORWARDING) 468 ++liveports; 469 } 470 471 if (liveports == 0) 472 netif_carrier_off(br->dev); 473 else 474 netif_carrier_on(br->dev); 475 } 476 477 /* called under bridge lock */ 478 static void br_topology_change_acknowledge(struct net_bridge_port *p) 479 { 480 p->topology_change_ack = 1; 481 br_transmit_config(p); 482 } 483 484 /* called under bridge lock */ 485 void br_received_config_bpdu(struct net_bridge_port *p, 486 const struct br_config_bpdu *bpdu) 487 { 488 struct net_bridge *br; 489 int was_root; 490 491 br = p->br; 492 was_root = br_is_root_bridge(br); 493 494 if (br_supersedes_port_info(p, bpdu)) { 495 br_record_config_information(p, bpdu); 496 br_configuration_update(br); 497 br_port_state_selection(br); 498 499 if (!br_is_root_bridge(br) && was_root) { 500 del_timer(&br->hello_timer); 501 if (br->topology_change_detected) { 502 del_timer(&br->topology_change_timer); 503 br_transmit_tcn(br); 504 505 mod_timer(&br->tcn_timer, 506 jiffies + br->bridge_hello_time); 507 } 508 } 509 510 if (p->port_no == br->root_port) { 511 br_record_config_timeout_values(br, bpdu); 512 br_config_bpdu_generation(br); 513 if (bpdu->topology_change_ack) 514 br_topology_change_acknowledged(br); 515 } 516 } else if (br_is_designated_port(p)) { 517 br_reply(p); 518 } 519 } 520 521 /* called under bridge lock */ 522 void br_received_tcn_bpdu(struct net_bridge_port *p) 523 { 524 if (br_is_designated_port(p)) { 525 br_info(p->br, "port %u(%s) received tcn bpdu\n", 526 (unsigned int) p->port_no, p->dev->name); 527 528 br_topology_change_detection(p->br); 529 br_topology_change_acknowledge(p); 530 } 531 } 532 533 /* Change bridge STP parameter */ 534 int br_set_hello_time(struct net_bridge *br, unsigned long val) 535 { 536 unsigned long t = clock_t_to_jiffies(val); 537 538 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME) 539 return -ERANGE; 540 541 spin_lock_bh(&br->lock); 542 br->bridge_hello_time = t; 543 if (br_is_root_bridge(br)) 544 br->hello_time = br->bridge_hello_time; 545 spin_unlock_bh(&br->lock); 546 return 0; 547 } 548 549 int br_set_max_age(struct net_bridge *br, unsigned long val) 550 { 551 unsigned long t = clock_t_to_jiffies(val); 552 553 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE) 554 return -ERANGE; 555 556 spin_lock_bh(&br->lock); 557 br->bridge_max_age = t; 558 if (br_is_root_bridge(br)) 559 br->max_age = br->bridge_max_age; 560 spin_unlock_bh(&br->lock); 561 return 0; 562 563 } 564 565 /* called under bridge lock */ 566 int __set_ageing_time(struct net_device *dev, unsigned long t) 567 { 568 struct switchdev_attr attr = { 569 .orig_dev = dev, 570 .id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME, 571 .flags = SWITCHDEV_F_SKIP_EOPNOTSUPP | SWITCHDEV_F_DEFER, 572 .u.ageing_time = jiffies_to_clock_t(t), 573 }; 574 int err; 575 576 err = switchdev_port_attr_set(dev, &attr); 577 if (err && err != -EOPNOTSUPP) 578 return err; 579 580 return 0; 581 } 582 583 /* Set time interval that dynamic forwarding entries live 584 * For pure software bridge, allow values outside the 802.1 585 * standard specification for special cases: 586 * 0 - entry never ages (all permanant) 587 * 1 - entry disappears (no persistance) 588 * 589 * Offloaded switch entries maybe more restrictive 590 */ 591 int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time) 592 { 593 unsigned long t = clock_t_to_jiffies(ageing_time); 594 int err; 595 596 err = __set_ageing_time(br->dev, t); 597 if (err) 598 return err; 599 600 spin_lock_bh(&br->lock); 601 br->bridge_ageing_time = t; 602 br->ageing_time = t; 603 spin_unlock_bh(&br->lock); 604 605 mod_delayed_work(system_long_wq, &br->gc_work, 0); 606 607 return 0; 608 } 609 610 /* called under bridge lock */ 611 void __br_set_topology_change(struct net_bridge *br, unsigned char val) 612 { 613 unsigned long t; 614 int err; 615 616 if (br->stp_enabled == BR_KERNEL_STP && br->topology_change != val) { 617 /* On topology change, set the bridge ageing time to twice the 618 * forward delay. Otherwise, restore its default ageing time. 619 */ 620 621 if (val) { 622 t = 2 * br->forward_delay; 623 br_debug(br, "decreasing ageing time to %lu\n", t); 624 } else { 625 t = br->bridge_ageing_time; 626 br_debug(br, "restoring ageing time to %lu\n", t); 627 } 628 629 err = __set_ageing_time(br->dev, t); 630 if (err) 631 br_warn(br, "error offloading ageing time\n"); 632 else 633 br->ageing_time = t; 634 } 635 636 br->topology_change = val; 637 } 638 639 void __br_set_forward_delay(struct net_bridge *br, unsigned long t) 640 { 641 br->bridge_forward_delay = t; 642 if (br_is_root_bridge(br)) 643 br->forward_delay = br->bridge_forward_delay; 644 } 645 646 int br_set_forward_delay(struct net_bridge *br, unsigned long val) 647 { 648 unsigned long t = clock_t_to_jiffies(val); 649 int err = -ERANGE; 650 651 spin_lock_bh(&br->lock); 652 if (br->stp_enabled != BR_NO_STP && 653 (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY)) 654 goto unlock; 655 656 __br_set_forward_delay(br, t); 657 err = 0; 658 659 unlock: 660 spin_unlock_bh(&br->lock); 661 return err; 662 } 663