1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Spanning tree protocol; generic parts 4 * Linux ethernet bridge 5 * 6 * Authors: 7 * Lennert Buytenhek <buytenh@gnu.org> 8 */ 9 #include <linux/kernel.h> 10 #include <linux/rculist.h> 11 #include <net/switchdev.h> 12 13 #include "br_private.h" 14 #include "br_private_stp.h" 15 16 /* since time values in bpdu are in jiffies and then scaled (1/256) 17 * before sending, make sure that is at least one STP tick. 18 */ 19 #define MESSAGE_AGE_INCR ((HZ / 256) + 1) 20 21 static const char *const br_port_state_names[] = { 22 [BR_STATE_DISABLED] = "disabled", 23 [BR_STATE_LISTENING] = "listening", 24 [BR_STATE_LEARNING] = "learning", 25 [BR_STATE_FORWARDING] = "forwarding", 26 [BR_STATE_BLOCKING] = "blocking", 27 }; 28 29 void br_set_state(struct net_bridge_port *p, unsigned int state) 30 { 31 struct switchdev_attr attr = { 32 .orig_dev = p->dev, 33 .id = SWITCHDEV_ATTR_ID_PORT_STP_STATE, 34 .flags = SWITCHDEV_F_DEFER, 35 .u.stp_state = state, 36 }; 37 int err; 38 39 /* Don't change the state of the ports if they are driven by a different 40 * protocol. 41 */ 42 if (p->flags & BR_MRP_AWARE) 43 return; 44 45 p->state = state; 46 if (br_opt_get(p->br, BROPT_MST_ENABLED)) { 47 err = br_mst_set_state(p, 0, state, NULL); 48 if (err) 49 br_warn(p->br, "error setting MST state on port %u(%s)\n", 50 p->port_no, netdev_name(p->dev)); 51 } 52 err = switchdev_port_attr_set(p->dev, &attr, NULL); 53 if (err && err != -EOPNOTSUPP) 54 br_warn(p->br, "error setting offload STP state on port %u(%s)\n", 55 (unsigned int) p->port_no, p->dev->name); 56 else 57 br_info(p->br, "port %u(%s) entered %s state\n", 58 (unsigned int) p->port_no, p->dev->name, 59 br_port_state_names[p->state]); 60 61 if (p->br->stp_enabled == BR_KERNEL_STP) { 62 switch (p->state) { 63 case BR_STATE_BLOCKING: 64 p->stp_xstats.transition_blk++; 65 break; 66 case BR_STATE_FORWARDING: 67 p->stp_xstats.transition_fwd++; 68 break; 69 } 70 } 71 } 72 73 u8 br_port_get_stp_state(const struct net_device *dev) 74 { 75 struct net_bridge_port *p; 76 77 ASSERT_RTNL(); 78 79 p = br_port_get_rtnl(dev); 80 if (!p) 81 return BR_STATE_DISABLED; 82 83 return p->state; 84 } 85 EXPORT_SYMBOL_GPL(br_port_get_stp_state); 86 87 /* called under bridge lock */ 88 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no) 89 { 90 struct net_bridge_port *p; 91 92 list_for_each_entry_rcu(p, &br->port_list, list, 93 lockdep_is_held(&br->lock)) { 94 if (p->port_no == port_no) 95 return p; 96 } 97 98 return NULL; 99 } 100 101 /* called under bridge lock */ 102 static int br_should_become_root_port(const struct net_bridge_port *p, 103 u16 root_port) 104 { 105 struct net_bridge *br; 106 struct net_bridge_port *rp; 107 int t; 108 109 br = p->br; 110 if (p->state == BR_STATE_DISABLED || 111 br_is_designated_port(p)) 112 return 0; 113 114 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0) 115 return 0; 116 117 if (!root_port) 118 return 1; 119 120 rp = br_get_port(br, root_port); 121 122 t = memcmp(&p->designated_root, &rp->designated_root, 8); 123 if (t < 0) 124 return 1; 125 else if (t > 0) 126 return 0; 127 128 if (p->designated_cost + p->path_cost < 129 rp->designated_cost + rp->path_cost) 130 return 1; 131 else if (p->designated_cost + p->path_cost > 132 rp->designated_cost + rp->path_cost) 133 return 0; 134 135 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8); 136 if (t < 0) 137 return 1; 138 else if (t > 0) 139 return 0; 140 141 if (p->designated_port < rp->designated_port) 142 return 1; 143 else if (p->designated_port > rp->designated_port) 144 return 0; 145 146 if (p->port_id < rp->port_id) 147 return 1; 148 149 return 0; 150 } 151 152 static void br_root_port_block(const struct net_bridge *br, 153 struct net_bridge_port *p) 154 { 155 156 br_notice(br, "port %u(%s) tried to become root port (blocked)", 157 (unsigned int) p->port_no, p->dev->name); 158 159 br_set_state(p, BR_STATE_LISTENING); 160 br_ifinfo_notify(RTM_NEWLINK, NULL, p); 161 162 if (br->forward_delay > 0) 163 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); 164 } 165 166 /* called under bridge lock */ 167 static void br_root_selection(struct net_bridge *br) 168 { 169 struct net_bridge_port *p; 170 u16 root_port = 0; 171 172 list_for_each_entry(p, &br->port_list, list) { 173 if (!br_should_become_root_port(p, root_port)) 174 continue; 175 176 if (p->flags & BR_ROOT_BLOCK) 177 br_root_port_block(br, p); 178 else 179 root_port = p->port_no; 180 } 181 182 br->root_port = root_port; 183 184 if (!root_port) { 185 br->designated_root = br->bridge_id; 186 br->root_path_cost = 0; 187 } else { 188 p = br_get_port(br, root_port); 189 br->designated_root = p->designated_root; 190 br->root_path_cost = p->designated_cost + p->path_cost; 191 } 192 } 193 194 /* called under bridge lock */ 195 void br_become_root_bridge(struct net_bridge *br) 196 { 197 br->max_age = br->bridge_max_age; 198 br->hello_time = br->bridge_hello_time; 199 br->forward_delay = br->bridge_forward_delay; 200 br_topology_change_detection(br); 201 del_timer(&br->tcn_timer); 202 203 if (br->dev->flags & IFF_UP) { 204 br_config_bpdu_generation(br); 205 mod_timer(&br->hello_timer, jiffies + br->hello_time); 206 } 207 } 208 209 /* called under bridge lock */ 210 void br_transmit_config(struct net_bridge_port *p) 211 { 212 struct br_config_bpdu bpdu; 213 struct net_bridge *br; 214 215 if (timer_pending(&p->hold_timer)) { 216 p->config_pending = 1; 217 return; 218 } 219 220 br = p->br; 221 222 bpdu.topology_change = br->topology_change; 223 bpdu.topology_change_ack = p->topology_change_ack; 224 bpdu.root = br->designated_root; 225 bpdu.root_path_cost = br->root_path_cost; 226 bpdu.bridge_id = br->bridge_id; 227 bpdu.port_id = p->port_id; 228 if (br_is_root_bridge(br)) 229 bpdu.message_age = 0; 230 else { 231 struct net_bridge_port *root 232 = br_get_port(br, br->root_port); 233 bpdu.message_age = (jiffies - root->designated_age) 234 + MESSAGE_AGE_INCR; 235 } 236 bpdu.max_age = br->max_age; 237 bpdu.hello_time = br->hello_time; 238 bpdu.forward_delay = br->forward_delay; 239 240 if (bpdu.message_age < br->max_age) { 241 br_send_config_bpdu(p, &bpdu); 242 p->topology_change_ack = 0; 243 p->config_pending = 0; 244 if (p->br->stp_enabled == BR_KERNEL_STP) 245 mod_timer(&p->hold_timer, 246 round_jiffies(jiffies + BR_HOLD_TIME)); 247 } 248 } 249 250 /* called under bridge lock */ 251 static void br_record_config_information(struct net_bridge_port *p, 252 const struct br_config_bpdu *bpdu) 253 { 254 p->designated_root = bpdu->root; 255 p->designated_cost = bpdu->root_path_cost; 256 p->designated_bridge = bpdu->bridge_id; 257 p->designated_port = bpdu->port_id; 258 p->designated_age = jiffies - bpdu->message_age; 259 260 mod_timer(&p->message_age_timer, jiffies 261 + (bpdu->max_age - bpdu->message_age)); 262 } 263 264 /* called under bridge lock */ 265 static void br_record_config_timeout_values(struct net_bridge *br, 266 const struct br_config_bpdu *bpdu) 267 { 268 br->max_age = bpdu->max_age; 269 br->hello_time = bpdu->hello_time; 270 br->forward_delay = bpdu->forward_delay; 271 __br_set_topology_change(br, bpdu->topology_change); 272 } 273 274 /* called under bridge lock */ 275 void br_transmit_tcn(struct net_bridge *br) 276 { 277 struct net_bridge_port *p; 278 279 p = br_get_port(br, br->root_port); 280 if (p) 281 br_send_tcn_bpdu(p); 282 else 283 br_notice(br, "root port %u not found for topology notice\n", 284 br->root_port); 285 } 286 287 /* called under bridge lock */ 288 static int br_should_become_designated_port(const struct net_bridge_port *p) 289 { 290 struct net_bridge *br; 291 int t; 292 293 br = p->br; 294 if (br_is_designated_port(p)) 295 return 1; 296 297 if (memcmp(&p->designated_root, &br->designated_root, 8)) 298 return 1; 299 300 if (br->root_path_cost < p->designated_cost) 301 return 1; 302 else if (br->root_path_cost > p->designated_cost) 303 return 0; 304 305 t = memcmp(&br->bridge_id, &p->designated_bridge, 8); 306 if (t < 0) 307 return 1; 308 else if (t > 0) 309 return 0; 310 311 if (p->port_id < p->designated_port) 312 return 1; 313 314 return 0; 315 } 316 317 /* called under bridge lock */ 318 static void br_designated_port_selection(struct net_bridge *br) 319 { 320 struct net_bridge_port *p; 321 322 list_for_each_entry(p, &br->port_list, list) { 323 if (p->state != BR_STATE_DISABLED && 324 br_should_become_designated_port(p)) 325 br_become_designated_port(p); 326 327 } 328 } 329 330 /* called under bridge lock */ 331 static int br_supersedes_port_info(const struct net_bridge_port *p, 332 const struct br_config_bpdu *bpdu) 333 { 334 int t; 335 336 t = memcmp(&bpdu->root, &p->designated_root, 8); 337 if (t < 0) 338 return 1; 339 else if (t > 0) 340 return 0; 341 342 if (bpdu->root_path_cost < p->designated_cost) 343 return 1; 344 else if (bpdu->root_path_cost > p->designated_cost) 345 return 0; 346 347 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8); 348 if (t < 0) 349 return 1; 350 else if (t > 0) 351 return 0; 352 353 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8)) 354 return 1; 355 356 if (bpdu->port_id <= p->designated_port) 357 return 1; 358 359 return 0; 360 } 361 362 /* called under bridge lock */ 363 static void br_topology_change_acknowledged(struct net_bridge *br) 364 { 365 br->topology_change_detected = 0; 366 del_timer(&br->tcn_timer); 367 } 368 369 /* called under bridge lock */ 370 void br_topology_change_detection(struct net_bridge *br) 371 { 372 int isroot = br_is_root_bridge(br); 373 374 if (br->stp_enabled != BR_KERNEL_STP) 375 return; 376 377 br_info(br, "topology change detected, %s\n", 378 isroot ? "propagating" : "sending tcn bpdu"); 379 380 if (isroot) { 381 __br_set_topology_change(br, 1); 382 mod_timer(&br->topology_change_timer, jiffies 383 + br->bridge_forward_delay + br->bridge_max_age); 384 } else if (!br->topology_change_detected) { 385 br_transmit_tcn(br); 386 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time); 387 } 388 389 br->topology_change_detected = 1; 390 } 391 392 /* called under bridge lock */ 393 void br_config_bpdu_generation(struct net_bridge *br) 394 { 395 struct net_bridge_port *p; 396 397 list_for_each_entry(p, &br->port_list, list) { 398 if (p->state != BR_STATE_DISABLED && 399 br_is_designated_port(p)) 400 br_transmit_config(p); 401 } 402 } 403 404 /* called under bridge lock */ 405 static void br_reply(struct net_bridge_port *p) 406 { 407 br_transmit_config(p); 408 } 409 410 /* called under bridge lock */ 411 void br_configuration_update(struct net_bridge *br) 412 { 413 br_root_selection(br); 414 br_designated_port_selection(br); 415 } 416 417 /* called under bridge lock */ 418 void br_become_designated_port(struct net_bridge_port *p) 419 { 420 struct net_bridge *br; 421 422 br = p->br; 423 p->designated_root = br->designated_root; 424 p->designated_cost = br->root_path_cost; 425 p->designated_bridge = br->bridge_id; 426 p->designated_port = p->port_id; 427 } 428 429 430 /* called under bridge lock */ 431 static void br_make_blocking(struct net_bridge_port *p) 432 { 433 if (p->state != BR_STATE_DISABLED && 434 p->state != BR_STATE_BLOCKING) { 435 if (p->state == BR_STATE_FORWARDING || 436 p->state == BR_STATE_LEARNING) 437 br_topology_change_detection(p->br); 438 439 br_set_state(p, BR_STATE_BLOCKING); 440 br_ifinfo_notify(RTM_NEWLINK, NULL, p); 441 442 del_timer(&p->forward_delay_timer); 443 } 444 } 445 446 /* called under bridge lock */ 447 static void br_make_forwarding(struct net_bridge_port *p) 448 { 449 struct net_bridge *br = p->br; 450 451 if (p->state != BR_STATE_BLOCKING) 452 return; 453 454 if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) { 455 br_set_state(p, BR_STATE_FORWARDING); 456 br_topology_change_detection(br); 457 del_timer(&p->forward_delay_timer); 458 } else if (br->stp_enabled == BR_KERNEL_STP) 459 br_set_state(p, BR_STATE_LISTENING); 460 else 461 br_set_state(p, BR_STATE_LEARNING); 462 463 br_ifinfo_notify(RTM_NEWLINK, NULL, p); 464 465 if (br->forward_delay != 0) 466 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); 467 } 468 469 /* called under bridge lock */ 470 void br_port_state_selection(struct net_bridge *br) 471 { 472 struct net_bridge_port *p; 473 unsigned int liveports = 0; 474 475 list_for_each_entry(p, &br->port_list, list) { 476 if (p->state == BR_STATE_DISABLED) 477 continue; 478 479 /* Don't change port states if userspace is handling STP */ 480 if (br->stp_enabled != BR_USER_STP) { 481 if (p->port_no == br->root_port) { 482 p->config_pending = 0; 483 p->topology_change_ack = 0; 484 br_make_forwarding(p); 485 } else if (br_is_designated_port(p)) { 486 del_timer(&p->message_age_timer); 487 br_make_forwarding(p); 488 } else { 489 p->config_pending = 0; 490 p->topology_change_ack = 0; 491 br_make_blocking(p); 492 } 493 } 494 495 if (p->state != BR_STATE_BLOCKING) 496 br_multicast_enable_port(p); 497 /* Multicast is not disabled for the port when it goes in 498 * blocking state because the timers will expire and stop by 499 * themselves without sending more queries. 500 */ 501 if (p->state == BR_STATE_FORWARDING) 502 ++liveports; 503 } 504 505 if (liveports == 0) 506 netif_carrier_off(br->dev); 507 else 508 netif_carrier_on(br->dev); 509 } 510 511 /* called under bridge lock */ 512 static void br_topology_change_acknowledge(struct net_bridge_port *p) 513 { 514 p->topology_change_ack = 1; 515 br_transmit_config(p); 516 } 517 518 /* called under bridge lock */ 519 void br_received_config_bpdu(struct net_bridge_port *p, 520 const struct br_config_bpdu *bpdu) 521 { 522 struct net_bridge *br; 523 int was_root; 524 525 p->stp_xstats.rx_bpdu++; 526 527 br = p->br; 528 was_root = br_is_root_bridge(br); 529 530 if (br_supersedes_port_info(p, bpdu)) { 531 br_record_config_information(p, bpdu); 532 br_configuration_update(br); 533 br_port_state_selection(br); 534 535 if (!br_is_root_bridge(br) && was_root) { 536 del_timer(&br->hello_timer); 537 if (br->topology_change_detected) { 538 del_timer(&br->topology_change_timer); 539 br_transmit_tcn(br); 540 541 mod_timer(&br->tcn_timer, 542 jiffies + br->bridge_hello_time); 543 } 544 } 545 546 if (p->port_no == br->root_port) { 547 br_record_config_timeout_values(br, bpdu); 548 br_config_bpdu_generation(br); 549 if (bpdu->topology_change_ack) 550 br_topology_change_acknowledged(br); 551 } 552 } else if (br_is_designated_port(p)) { 553 br_reply(p); 554 } 555 } 556 557 /* called under bridge lock */ 558 void br_received_tcn_bpdu(struct net_bridge_port *p) 559 { 560 p->stp_xstats.rx_tcn++; 561 562 if (br_is_designated_port(p)) { 563 br_info(p->br, "port %u(%s) received tcn bpdu\n", 564 (unsigned int) p->port_no, p->dev->name); 565 566 br_topology_change_detection(p->br); 567 br_topology_change_acknowledge(p); 568 } 569 } 570 571 /* Change bridge STP parameter */ 572 int br_set_hello_time(struct net_bridge *br, unsigned long val) 573 { 574 unsigned long t = clock_t_to_jiffies(val); 575 576 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME) 577 return -ERANGE; 578 579 spin_lock_bh(&br->lock); 580 br->bridge_hello_time = t; 581 if (br_is_root_bridge(br)) 582 br->hello_time = br->bridge_hello_time; 583 spin_unlock_bh(&br->lock); 584 return 0; 585 } 586 587 int br_set_max_age(struct net_bridge *br, unsigned long val) 588 { 589 unsigned long t = clock_t_to_jiffies(val); 590 591 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE) 592 return -ERANGE; 593 594 spin_lock_bh(&br->lock); 595 br->bridge_max_age = t; 596 if (br_is_root_bridge(br)) 597 br->max_age = br->bridge_max_age; 598 spin_unlock_bh(&br->lock); 599 return 0; 600 601 } 602 603 /* called under bridge lock */ 604 int __set_ageing_time(struct net_device *dev, unsigned long t) 605 { 606 struct switchdev_attr attr = { 607 .orig_dev = dev, 608 .id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME, 609 .flags = SWITCHDEV_F_SKIP_EOPNOTSUPP | SWITCHDEV_F_DEFER, 610 .u.ageing_time = jiffies_to_clock_t(t), 611 }; 612 int err; 613 614 err = switchdev_port_attr_set(dev, &attr, NULL); 615 if (err && err != -EOPNOTSUPP) 616 return err; 617 618 return 0; 619 } 620 621 /* Set time interval that dynamic forwarding entries live 622 * For pure software bridge, allow values outside the 802.1 623 * standard specification for special cases: 624 * 0 - entry never ages (all permanent) 625 * 1 - entry disappears (no persistence) 626 * 627 * Offloaded switch entries maybe more restrictive 628 */ 629 int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time) 630 { 631 unsigned long t = clock_t_to_jiffies(ageing_time); 632 int err; 633 634 err = __set_ageing_time(br->dev, t); 635 if (err) 636 return err; 637 638 spin_lock_bh(&br->lock); 639 br->bridge_ageing_time = t; 640 br->ageing_time = t; 641 spin_unlock_bh(&br->lock); 642 643 mod_delayed_work(system_long_wq, &br->gc_work, 0); 644 645 return 0; 646 } 647 648 clock_t br_get_ageing_time(const struct net_device *br_dev) 649 { 650 const struct net_bridge *br; 651 652 if (!netif_is_bridge_master(br_dev)) 653 return 0; 654 655 br = netdev_priv(br_dev); 656 657 return jiffies_to_clock_t(br->ageing_time); 658 } 659 EXPORT_SYMBOL_GPL(br_get_ageing_time); 660 661 /* called under bridge lock */ 662 void __br_set_topology_change(struct net_bridge *br, unsigned char val) 663 { 664 unsigned long t; 665 int err; 666 667 if (br->stp_enabled == BR_KERNEL_STP && br->topology_change != val) { 668 /* On topology change, set the bridge ageing time to twice the 669 * forward delay. Otherwise, restore its default ageing time. 670 */ 671 672 if (val) { 673 t = 2 * br->forward_delay; 674 br_debug(br, "decreasing ageing time to %lu\n", t); 675 } else { 676 t = br->bridge_ageing_time; 677 br_debug(br, "restoring ageing time to %lu\n", t); 678 } 679 680 err = __set_ageing_time(br->dev, t); 681 if (err) 682 br_warn(br, "error offloading ageing time\n"); 683 else 684 br->ageing_time = t; 685 } 686 687 br->topology_change = val; 688 } 689 690 void __br_set_forward_delay(struct net_bridge *br, unsigned long t) 691 { 692 br->bridge_forward_delay = t; 693 if (br_is_root_bridge(br)) 694 br->forward_delay = br->bridge_forward_delay; 695 } 696 697 int br_set_forward_delay(struct net_bridge *br, unsigned long val) 698 { 699 unsigned long t = clock_t_to_jiffies(val); 700 int err = -ERANGE; 701 702 spin_lock_bh(&br->lock); 703 if (br->stp_enabled != BR_NO_STP && 704 (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY)) 705 goto unlock; 706 707 __br_set_forward_delay(br, t); 708 err = 0; 709 710 unlock: 711 spin_unlock_bh(&br->lock); 712 return err; 713 } 714