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 u32 p_path_cost, rp_path_cost, p_designated_cost, rp_designated_cost; 106 struct net_bridge_port *rp; 107 struct net_bridge *br; 108 int t; 109 110 br = p->br; 111 if (p->state == BR_STATE_DISABLED || 112 br_is_designated_port(p)) 113 return 0; 114 115 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0) 116 return 0; 117 118 if (!root_port) 119 return 1; 120 121 rp = br_get_port(br, root_port); 122 123 t = memcmp(&p->designated_root, &rp->designated_root, 8); 124 if (t < 0) 125 return 1; 126 else if (t > 0) 127 return 0; 128 129 p_path_cost = READ_ONCE(p->path_cost); 130 rp_path_cost = READ_ONCE(rp->path_cost); 131 p_designated_cost = READ_ONCE(p->designated_cost); 132 rp_designated_cost = READ_ONCE(rp->designated_cost); 133 134 if (p_designated_cost + p_path_cost < 135 rp_designated_cost + rp_path_cost) 136 return 1; 137 else if (p_designated_cost + p_path_cost > 138 rp_designated_cost + rp_path_cost) 139 return 0; 140 141 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8); 142 if (t < 0) 143 return 1; 144 else if (t > 0) 145 return 0; 146 147 if (p->designated_port < rp->designated_port) 148 return 1; 149 else if (p->designated_port > rp->designated_port) 150 return 0; 151 152 if (p->port_id < rp->port_id) 153 return 1; 154 155 return 0; 156 } 157 158 static void br_root_port_block(const struct net_bridge *br, 159 struct net_bridge_port *p) 160 { 161 162 br_notice(br, "port %u(%s) tried to become root port (blocked)", 163 (unsigned int) p->port_no, p->dev->name); 164 165 br_set_state(p, BR_STATE_LISTENING); 166 br_ifinfo_notify(RTM_NEWLINK, NULL, p); 167 168 if (br->forward_delay > 0) 169 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); 170 } 171 172 /* called under bridge lock */ 173 static void br_root_selection(struct net_bridge *br) 174 { 175 struct net_bridge_port *p; 176 u16 root_port = 0; 177 178 list_for_each_entry(p, &br->port_list, list) { 179 if (!br_should_become_root_port(p, root_port)) 180 continue; 181 182 if (p->flags & BR_ROOT_BLOCK) 183 br_root_port_block(br, p); 184 else 185 root_port = p->port_no; 186 } 187 188 br->root_port = root_port; 189 190 if (!root_port) { 191 br->designated_root = br->bridge_id; 192 br->root_path_cost = 0; 193 } else { 194 p = br_get_port(br, root_port); 195 br->designated_root = p->designated_root; 196 br->root_path_cost = READ_ONCE(p->designated_cost) + 197 READ_ONCE(p->path_cost); 198 } 199 } 200 201 /* called under bridge lock */ 202 void br_become_root_bridge(struct net_bridge *br) 203 { 204 br->max_age = br->bridge_max_age; 205 br->hello_time = br->bridge_hello_time; 206 br->forward_delay = br->bridge_forward_delay; 207 br_topology_change_detection(br); 208 timer_delete(&br->tcn_timer); 209 210 if (br->dev->flags & IFF_UP) { 211 br_config_bpdu_generation(br); 212 mod_timer(&br->hello_timer, jiffies + br->hello_time); 213 } 214 } 215 216 /* called under bridge lock */ 217 void br_transmit_config(struct net_bridge_port *p) 218 { 219 struct br_config_bpdu bpdu; 220 struct net_bridge *br; 221 222 if (timer_pending(&p->hold_timer)) { 223 WRITE_ONCE(p->config_pending, 1); 224 return; 225 } 226 227 br = p->br; 228 229 bpdu.topology_change = br->topology_change; 230 bpdu.topology_change_ack = p->topology_change_ack; 231 bpdu.root = br->designated_root; 232 bpdu.root_path_cost = br->root_path_cost; 233 bpdu.bridge_id = br->bridge_id; 234 bpdu.port_id = p->port_id; 235 if (br_is_root_bridge(br)) 236 bpdu.message_age = 0; 237 else { 238 struct net_bridge_port *root 239 = br_get_port(br, br->root_port); 240 bpdu.message_age = (jiffies - root->designated_age) 241 + MESSAGE_AGE_INCR; 242 } 243 bpdu.max_age = br->max_age; 244 bpdu.hello_time = br->hello_time; 245 bpdu.forward_delay = br->forward_delay; 246 247 if (bpdu.message_age < br->max_age) { 248 br_send_config_bpdu(p, &bpdu); 249 p->topology_change_ack = 0; 250 WRITE_ONCE(p->config_pending, 0); 251 if (p->br->stp_enabled == BR_KERNEL_STP) 252 mod_timer(&p->hold_timer, 253 round_jiffies(jiffies + BR_HOLD_TIME)); 254 } 255 } 256 257 /* called under bridge lock */ 258 static void br_record_config_information(struct net_bridge_port *p, 259 const struct br_config_bpdu *bpdu) 260 { 261 p->designated_root = bpdu->root; 262 WRITE_ONCE(p->designated_cost, bpdu->root_path_cost); 263 p->designated_bridge = bpdu->bridge_id; 264 WRITE_ONCE(p->designated_port, bpdu->port_id); 265 p->designated_age = jiffies - bpdu->message_age; 266 267 mod_timer(&p->message_age_timer, jiffies 268 + (bpdu->max_age - bpdu->message_age)); 269 } 270 271 /* called under bridge lock */ 272 static void br_record_config_timeout_values(struct net_bridge *br, 273 const struct br_config_bpdu *bpdu) 274 { 275 br->max_age = bpdu->max_age; 276 br->hello_time = bpdu->hello_time; 277 br->forward_delay = bpdu->forward_delay; 278 __br_set_topology_change(br, bpdu->topology_change); 279 } 280 281 /* called under bridge lock */ 282 void br_transmit_tcn(struct net_bridge *br) 283 { 284 struct net_bridge_port *p; 285 286 p = br_get_port(br, br->root_port); 287 if (p) 288 br_send_tcn_bpdu(p); 289 else 290 br_notice(br, "root port %u not found for topology notice\n", 291 br->root_port); 292 } 293 294 /* called under bridge lock */ 295 static int br_should_become_designated_port(const struct net_bridge_port *p) 296 { 297 struct net_bridge *br; 298 u32 p_designated_cost; 299 int t; 300 301 br = p->br; 302 if (br_is_designated_port(p)) 303 return 1; 304 305 if (memcmp(&p->designated_root, &br->designated_root, 8)) 306 return 1; 307 308 p_designated_cost = READ_ONCE(p->designated_cost); 309 if (br->root_path_cost < p_designated_cost) 310 return 1; 311 else if (br->root_path_cost > p_designated_cost) 312 return 0; 313 314 t = memcmp(&br->bridge_id, &p->designated_bridge, 8); 315 if (t < 0) 316 return 1; 317 else if (t > 0) 318 return 0; 319 320 if (p->port_id < p->designated_port) 321 return 1; 322 323 return 0; 324 } 325 326 /* called under bridge lock */ 327 static void br_designated_port_selection(struct net_bridge *br) 328 { 329 struct net_bridge_port *p; 330 331 list_for_each_entry(p, &br->port_list, list) { 332 if (p->state != BR_STATE_DISABLED && 333 br_should_become_designated_port(p)) 334 br_become_designated_port(p); 335 336 } 337 } 338 339 /* called under bridge lock */ 340 static int br_supersedes_port_info(const struct net_bridge_port *p, 341 const struct br_config_bpdu *bpdu) 342 { 343 u32 p_designated_cost; 344 int t; 345 346 t = memcmp(&bpdu->root, &p->designated_root, 8); 347 if (t < 0) 348 return 1; 349 else if (t > 0) 350 return 0; 351 352 p_designated_cost = READ_ONCE(p->designated_cost); 353 if (bpdu->root_path_cost < p_designated_cost) 354 return 1; 355 else if (bpdu->root_path_cost > p_designated_cost) 356 return 0; 357 358 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8); 359 if (t < 0) 360 return 1; 361 else if (t > 0) 362 return 0; 363 364 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8)) 365 return 1; 366 367 if (bpdu->port_id <= p->designated_port) 368 return 1; 369 370 return 0; 371 } 372 373 /* called under bridge lock */ 374 static void br_topology_change_acknowledged(struct net_bridge *br) 375 { 376 br->topology_change_detected = 0; 377 timer_delete(&br->tcn_timer); 378 } 379 380 /* called under bridge lock */ 381 void br_topology_change_detection(struct net_bridge *br) 382 { 383 int isroot = br_is_root_bridge(br); 384 385 if (br->stp_enabled != BR_KERNEL_STP) 386 return; 387 388 br_info(br, "topology change detected, %s\n", 389 isroot ? "propagating" : "sending tcn bpdu"); 390 391 if (isroot) { 392 __br_set_topology_change(br, 1); 393 mod_timer(&br->topology_change_timer, jiffies 394 + br->bridge_forward_delay + br->bridge_max_age); 395 } else if (!br->topology_change_detected) { 396 br_transmit_tcn(br); 397 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time); 398 } 399 400 br->topology_change_detected = 1; 401 } 402 403 /* called under bridge lock */ 404 void br_config_bpdu_generation(struct net_bridge *br) 405 { 406 struct net_bridge_port *p; 407 408 list_for_each_entry(p, &br->port_list, list) { 409 if (p->state != BR_STATE_DISABLED && 410 br_is_designated_port(p)) 411 br_transmit_config(p); 412 } 413 } 414 415 /* called under bridge lock */ 416 static void br_reply(struct net_bridge_port *p) 417 { 418 br_transmit_config(p); 419 } 420 421 /* called under bridge lock */ 422 void br_configuration_update(struct net_bridge *br) 423 { 424 br_root_selection(br); 425 br_designated_port_selection(br); 426 } 427 428 /* called under bridge lock */ 429 void br_become_designated_port(struct net_bridge_port *p) 430 { 431 struct net_bridge *br; 432 433 br = p->br; 434 p->designated_root = br->designated_root; 435 WRITE_ONCE(p->designated_cost, br->root_path_cost); 436 p->designated_bridge = br->bridge_id; 437 WRITE_ONCE(p->designated_port, p->port_id); 438 } 439 440 441 /* called under bridge lock */ 442 static void br_make_blocking(struct net_bridge_port *p) 443 { 444 if (p->state != BR_STATE_DISABLED && 445 p->state != BR_STATE_BLOCKING) { 446 if (p->state == BR_STATE_FORWARDING || 447 p->state == BR_STATE_LEARNING) 448 br_topology_change_detection(p->br); 449 450 br_set_state(p, BR_STATE_BLOCKING); 451 br_ifinfo_notify(RTM_NEWLINK, NULL, p); 452 453 timer_delete(&p->forward_delay_timer); 454 } 455 } 456 457 /* called under bridge lock */ 458 static void br_make_forwarding(struct net_bridge_port *p) 459 { 460 struct net_bridge *br = p->br; 461 462 if (p->state != BR_STATE_BLOCKING) 463 return; 464 465 if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) { 466 br_set_state(p, BR_STATE_FORWARDING); 467 br_topology_change_detection(br); 468 timer_delete(&p->forward_delay_timer); 469 } else if (br->stp_enabled == BR_KERNEL_STP) 470 br_set_state(p, BR_STATE_LISTENING); 471 else 472 br_set_state(p, BR_STATE_LEARNING); 473 474 br_ifinfo_notify(RTM_NEWLINK, NULL, p); 475 476 if (br->forward_delay != 0) 477 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); 478 } 479 480 /* called under bridge lock */ 481 void br_port_state_selection(struct net_bridge *br) 482 { 483 struct net_bridge_port *p; 484 unsigned int liveports = 0; 485 486 list_for_each_entry(p, &br->port_list, list) { 487 if (p->state == BR_STATE_DISABLED) 488 continue; 489 490 /* Don't change port states if userspace is handling STP */ 491 if (br->stp_enabled != BR_USER_STP) { 492 if (p->port_no == br->root_port) { 493 WRITE_ONCE(p->config_pending, 0); 494 p->topology_change_ack = 0; 495 br_make_forwarding(p); 496 } else if (br_is_designated_port(p)) { 497 timer_delete(&p->message_age_timer); 498 br_make_forwarding(p); 499 } else { 500 WRITE_ONCE(p->config_pending, 0); 501 p->topology_change_ack = 0; 502 br_make_blocking(p); 503 } 504 } 505 506 if (p->state != BR_STATE_BLOCKING) 507 br_multicast_enable_port(p); 508 /* Multicast is not disabled for the port when it goes in 509 * blocking state because the timers will expire and stop by 510 * themselves without sending more queries. 511 */ 512 if (p->state == BR_STATE_FORWARDING) 513 ++liveports; 514 } 515 516 if (liveports == 0) 517 netif_carrier_off(br->dev); 518 else 519 netif_carrier_on(br->dev); 520 } 521 522 /* called under bridge lock */ 523 static void br_topology_change_acknowledge(struct net_bridge_port *p) 524 { 525 p->topology_change_ack = 1; 526 br_transmit_config(p); 527 } 528 529 /* called under bridge lock */ 530 void br_received_config_bpdu(struct net_bridge_port *p, 531 const struct br_config_bpdu *bpdu) 532 { 533 struct net_bridge *br; 534 int was_root; 535 536 p->stp_xstats.rx_bpdu++; 537 538 br = p->br; 539 was_root = br_is_root_bridge(br); 540 541 if (br_supersedes_port_info(p, bpdu)) { 542 br_record_config_information(p, bpdu); 543 br_configuration_update(br); 544 br_port_state_selection(br); 545 546 if (!br_is_root_bridge(br) && was_root) { 547 timer_delete(&br->hello_timer); 548 if (br->topology_change_detected) { 549 timer_delete(&br->topology_change_timer); 550 br_transmit_tcn(br); 551 552 mod_timer(&br->tcn_timer, 553 jiffies + br->bridge_hello_time); 554 } 555 } 556 557 if (p->port_no == br->root_port) { 558 br_record_config_timeout_values(br, bpdu); 559 br_config_bpdu_generation(br); 560 if (bpdu->topology_change_ack) 561 br_topology_change_acknowledged(br); 562 } 563 } else if (br_is_designated_port(p)) { 564 br_reply(p); 565 } 566 } 567 568 /* called under bridge lock */ 569 void br_received_tcn_bpdu(struct net_bridge_port *p) 570 { 571 p->stp_xstats.rx_tcn++; 572 573 if (br_is_designated_port(p)) { 574 br_info(p->br, "port %u(%s) received tcn bpdu\n", 575 (unsigned int) p->port_no, p->dev->name); 576 577 br_topology_change_detection(p->br); 578 br_topology_change_acknowledge(p); 579 } 580 } 581 582 /* Change bridge STP parameter */ 583 int br_set_hello_time(struct net_bridge *br, unsigned long val) 584 { 585 unsigned long t = clock_t_to_jiffies(val); 586 587 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME) 588 return -ERANGE; 589 590 spin_lock_bh(&br->lock); 591 br->bridge_hello_time = t; 592 if (br_is_root_bridge(br)) 593 br->hello_time = br->bridge_hello_time; 594 spin_unlock_bh(&br->lock); 595 return 0; 596 } 597 598 int br_set_max_age(struct net_bridge *br, unsigned long val) 599 { 600 unsigned long t = clock_t_to_jiffies(val); 601 602 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE) 603 return -ERANGE; 604 605 spin_lock_bh(&br->lock); 606 br->bridge_max_age = t; 607 if (br_is_root_bridge(br)) 608 br->max_age = br->bridge_max_age; 609 spin_unlock_bh(&br->lock); 610 return 0; 611 612 } 613 614 /* called under bridge lock */ 615 int __set_ageing_time(struct net_device *dev, unsigned long t) 616 { 617 struct switchdev_attr attr = { 618 .orig_dev = dev, 619 .id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME, 620 .flags = SWITCHDEV_F_SKIP_EOPNOTSUPP | SWITCHDEV_F_DEFER, 621 .u.ageing_time = jiffies_to_clock_t(t), 622 }; 623 int err; 624 625 err = switchdev_port_attr_set(dev, &attr, NULL); 626 if (err && err != -EOPNOTSUPP) 627 return err; 628 629 return 0; 630 } 631 632 /* Set time interval that dynamic forwarding entries live 633 * For pure software bridge, allow values outside the 802.1 634 * standard specification for special cases: 635 * 0 - entry never ages (all permanent) 636 * 1 - entry disappears (no persistence) 637 * 638 * Offloaded switch entries maybe more restrictive 639 */ 640 int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time) 641 { 642 unsigned long t = clock_t_to_jiffies(ageing_time); 643 int err; 644 645 err = __set_ageing_time(br->dev, t); 646 if (err) 647 return err; 648 649 spin_lock_bh(&br->lock); 650 br->bridge_ageing_time = t; 651 br->ageing_time = t; 652 spin_unlock_bh(&br->lock); 653 654 mod_delayed_work(system_long_wq, &br->gc_work, 0); 655 656 return 0; 657 } 658 659 clock_t br_get_ageing_time(const struct net_device *br_dev) 660 { 661 const struct net_bridge *br; 662 663 if (!netif_is_bridge_master(br_dev)) 664 return 0; 665 666 br = netdev_priv(br_dev); 667 668 return jiffies_to_clock_t(br->ageing_time); 669 } 670 EXPORT_SYMBOL_GPL(br_get_ageing_time); 671 672 /* called under bridge lock */ 673 void __br_set_topology_change(struct net_bridge *br, unsigned char val) 674 { 675 unsigned long t; 676 int err; 677 678 if (br->stp_enabled == BR_KERNEL_STP && br->topology_change != val) { 679 /* On topology change, set the bridge ageing time to twice the 680 * forward delay. Otherwise, restore its default ageing time. 681 */ 682 683 if (val) { 684 t = 2 * br->forward_delay; 685 br_debug(br, "decreasing ageing time to %lu\n", t); 686 } else { 687 t = br->bridge_ageing_time; 688 br_debug(br, "restoring ageing time to %lu\n", t); 689 } 690 691 err = __set_ageing_time(br->dev, t); 692 if (err) 693 br_warn(br, "error offloading ageing time\n"); 694 else 695 br->ageing_time = t; 696 } 697 698 br->topology_change = val; 699 } 700 701 void __br_set_forward_delay(struct net_bridge *br, unsigned long t) 702 { 703 br->bridge_forward_delay = t; 704 if (br_is_root_bridge(br)) 705 br->forward_delay = br->bridge_forward_delay; 706 } 707 708 int br_set_forward_delay(struct net_bridge *br, unsigned long val) 709 { 710 unsigned long t = clock_t_to_jiffies(val); 711 int err = -ERANGE; 712 713 spin_lock_bh(&br->lock); 714 if (br->stp_enabled != BR_NO_STP && 715 (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY)) 716 goto unlock; 717 718 __br_set_forward_delay(br, t); 719 err = 0; 720 721 unlock: 722 spin_unlock_bh(&br->lock); 723 return err; 724 } 725