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 (test_bit(BR_MRP_AWARE_BIT, &p->flags)) 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 (test_bit(BR_ROOT_BLOCK_BIT, &p->flags)) 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 !(br->dev->flags & IFF_UP)) 387 return; 388 389 br_info(br, "topology change detected, %s\n", 390 isroot ? "propagating" : "sending tcn bpdu"); 391 392 if (isroot) { 393 __br_set_topology_change(br, 1); 394 mod_timer(&br->topology_change_timer, jiffies 395 + br->bridge_forward_delay + br->bridge_max_age); 396 } else if (!br->topology_change_detected) { 397 br_transmit_tcn(br); 398 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time); 399 } 400 401 br->topology_change_detected = 1; 402 } 403 404 /* called under bridge lock */ 405 void br_config_bpdu_generation(struct net_bridge *br) 406 { 407 struct net_bridge_port *p; 408 409 list_for_each_entry(p, &br->port_list, list) { 410 if (p->state != BR_STATE_DISABLED && 411 br_is_designated_port(p)) 412 br_transmit_config(p); 413 } 414 } 415 416 /* called under bridge lock */ 417 static void br_reply(struct net_bridge_port *p) 418 { 419 br_transmit_config(p); 420 } 421 422 /* called under bridge lock */ 423 void br_configuration_update(struct net_bridge *br) 424 { 425 br_root_selection(br); 426 br_designated_port_selection(br); 427 } 428 429 /* called under bridge lock */ 430 void br_become_designated_port(struct net_bridge_port *p) 431 { 432 struct net_bridge *br; 433 434 br = p->br; 435 p->designated_root = br->designated_root; 436 WRITE_ONCE(p->designated_cost, br->root_path_cost); 437 p->designated_bridge = br->bridge_id; 438 WRITE_ONCE(p->designated_port, p->port_id); 439 } 440 441 442 /* called under bridge lock */ 443 static void br_make_blocking(struct net_bridge_port *p) 444 { 445 if (p->state != BR_STATE_DISABLED && 446 p->state != BR_STATE_BLOCKING) { 447 if (p->state == BR_STATE_FORWARDING || 448 p->state == BR_STATE_LEARNING) 449 br_topology_change_detection(p->br); 450 451 br_set_state(p, BR_STATE_BLOCKING); 452 br_ifinfo_notify(RTM_NEWLINK, NULL, p); 453 454 timer_delete(&p->forward_delay_timer); 455 } 456 } 457 458 /* called under bridge lock */ 459 static void br_make_forwarding(struct net_bridge_port *p) 460 { 461 struct net_bridge *br = p->br; 462 463 if (p->state != BR_STATE_BLOCKING) 464 return; 465 466 if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) { 467 br_set_state(p, BR_STATE_FORWARDING); 468 br_topology_change_detection(br); 469 timer_delete(&p->forward_delay_timer); 470 } else if (br->stp_enabled == BR_KERNEL_STP) 471 br_set_state(p, BR_STATE_LISTENING); 472 else 473 br_set_state(p, BR_STATE_LEARNING); 474 475 br_ifinfo_notify(RTM_NEWLINK, NULL, p); 476 477 if (br->forward_delay != 0) 478 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); 479 } 480 481 /* called under bridge lock */ 482 void br_port_state_selection(struct net_bridge *br) 483 { 484 struct net_bridge_port *p; 485 unsigned int liveports = 0; 486 487 list_for_each_entry(p, &br->port_list, list) { 488 if (p->state == BR_STATE_DISABLED) 489 continue; 490 491 /* Don't change port states if userspace is handling STP */ 492 if (br->stp_enabled != BR_USER_STP) { 493 if (p->port_no == br->root_port) { 494 WRITE_ONCE(p->config_pending, 0); 495 p->topology_change_ack = 0; 496 br_make_forwarding(p); 497 } else if (br_is_designated_port(p)) { 498 timer_delete(&p->message_age_timer); 499 br_make_forwarding(p); 500 } else { 501 WRITE_ONCE(p->config_pending, 0); 502 p->topology_change_ack = 0; 503 br_make_blocking(p); 504 } 505 } 506 507 if (p->state != BR_STATE_BLOCKING) 508 br_multicast_enable_port(p); 509 /* Multicast is not disabled for the port when it goes in 510 * blocking state because the timers will expire and stop by 511 * themselves without sending more queries. 512 */ 513 if (p->state == BR_STATE_FORWARDING) 514 ++liveports; 515 } 516 517 if (liveports == 0) 518 netif_carrier_off(br->dev); 519 else 520 netif_carrier_on(br->dev); 521 } 522 523 /* called under bridge lock */ 524 static void br_topology_change_acknowledge(struct net_bridge_port *p) 525 { 526 p->topology_change_ack = 1; 527 br_transmit_config(p); 528 } 529 530 /* called under bridge lock */ 531 void br_received_config_bpdu(struct net_bridge_port *p, 532 const struct br_config_bpdu *bpdu) 533 { 534 struct net_bridge *br; 535 int was_root; 536 537 p->stp_xstats.rx_bpdu++; 538 539 br = p->br; 540 was_root = br_is_root_bridge(br); 541 542 if (br_supersedes_port_info(p, bpdu)) { 543 br_record_config_information(p, bpdu); 544 br_configuration_update(br); 545 br_port_state_selection(br); 546 547 if (!br_is_root_bridge(br) && was_root) { 548 timer_delete(&br->hello_timer); 549 if (br->topology_change_detected) { 550 timer_delete(&br->topology_change_timer); 551 br_transmit_tcn(br); 552 553 mod_timer(&br->tcn_timer, 554 jiffies + br->bridge_hello_time); 555 } 556 } 557 558 if (p->port_no == br->root_port) { 559 br_record_config_timeout_values(br, bpdu); 560 br_config_bpdu_generation(br); 561 if (bpdu->topology_change_ack) 562 br_topology_change_acknowledged(br); 563 } 564 } else if (br_is_designated_port(p)) { 565 br_reply(p); 566 } 567 } 568 569 /* called under bridge lock */ 570 void br_received_tcn_bpdu(struct net_bridge_port *p) 571 { 572 p->stp_xstats.rx_tcn++; 573 574 if (br_is_designated_port(p)) { 575 br_info(p->br, "port %u(%s) received tcn bpdu\n", 576 (unsigned int) p->port_no, p->dev->name); 577 578 br_topology_change_detection(p->br); 579 br_topology_change_acknowledge(p); 580 } 581 } 582 583 /* Change bridge STP parameter */ 584 int br_set_hello_time(struct net_bridge *br, unsigned long val) 585 { 586 unsigned long t = clock_t_to_jiffies(val); 587 588 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME) 589 return -ERANGE; 590 591 spin_lock_bh(&br->lock); 592 br->bridge_hello_time = t; 593 if (br_is_root_bridge(br)) 594 br->hello_time = br->bridge_hello_time; 595 spin_unlock_bh(&br->lock); 596 return 0; 597 } 598 599 int br_set_max_age(struct net_bridge *br, unsigned long val) 600 { 601 unsigned long t = clock_t_to_jiffies(val); 602 603 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE) 604 return -ERANGE; 605 606 spin_lock_bh(&br->lock); 607 br->bridge_max_age = t; 608 if (br_is_root_bridge(br)) 609 br->max_age = br->bridge_max_age; 610 spin_unlock_bh(&br->lock); 611 return 0; 612 613 } 614 615 /* called under bridge lock */ 616 int __set_ageing_time(struct net_device *dev, unsigned long t) 617 { 618 struct switchdev_attr attr = { 619 .orig_dev = dev, 620 .id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME, 621 .flags = SWITCHDEV_F_SKIP_EOPNOTSUPP | SWITCHDEV_F_DEFER, 622 .u.ageing_time = jiffies_to_clock_t(t), 623 }; 624 int err; 625 626 err = switchdev_port_attr_set(dev, &attr, NULL); 627 if (err && err != -EOPNOTSUPP) 628 return err; 629 630 return 0; 631 } 632 633 /* Set time interval that dynamic forwarding entries live 634 * For pure software bridge, allow values outside the 802.1 635 * standard specification for special cases: 636 * 0 - entry never ages (all permanent) 637 * 1 - entry disappears (no persistence) 638 * 639 * Offloaded switch entries maybe more restrictive 640 */ 641 int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time) 642 { 643 unsigned long t = clock_t_to_jiffies(ageing_time); 644 int err; 645 646 err = __set_ageing_time(br->dev, t); 647 if (err) 648 return err; 649 650 spin_lock_bh(&br->lock); 651 br->bridge_ageing_time = t; 652 br->ageing_time = t; 653 spin_unlock_bh(&br->lock); 654 655 mod_delayed_work(system_long_wq, &br->gc_work, 0); 656 657 return 0; 658 } 659 660 clock_t br_get_ageing_time(const struct net_device *br_dev) 661 { 662 const struct net_bridge *br; 663 664 if (!netif_is_bridge_master(br_dev)) 665 return 0; 666 667 br = netdev_priv(br_dev); 668 669 return jiffies_to_clock_t(br->ageing_time); 670 } 671 EXPORT_SYMBOL_GPL(br_get_ageing_time); 672 673 /* called under bridge lock */ 674 void __br_set_topology_change(struct net_bridge *br, unsigned char val) 675 { 676 unsigned long t; 677 int err; 678 679 if (br->stp_enabled == BR_KERNEL_STP && br->topology_change != val) { 680 /* On topology change, set the bridge ageing time to twice the 681 * forward delay. Otherwise, restore its default ageing time. 682 */ 683 684 if (val) { 685 t = 2 * br->forward_delay; 686 br_debug(br, "decreasing ageing time to %lu\n", t); 687 } else { 688 t = br->bridge_ageing_time; 689 br_debug(br, "restoring ageing time to %lu\n", t); 690 } 691 692 err = __set_ageing_time(br->dev, t); 693 if (err) 694 br_warn(br, "error offloading ageing time\n"); 695 else 696 br->ageing_time = t; 697 } 698 699 br->topology_change = val; 700 } 701 702 void __br_set_forward_delay(struct net_bridge *br, unsigned long t) 703 { 704 br->bridge_forward_delay = t; 705 if (br_is_root_bridge(br)) 706 br->forward_delay = br->bridge_forward_delay; 707 } 708 709 int br_set_forward_delay(struct net_bridge *br, unsigned long val) 710 { 711 unsigned long t = clock_t_to_jiffies(val); 712 int err = -ERANGE; 713 714 spin_lock_bh(&br->lock); 715 if (br->stp_enabled != BR_NO_STP && 716 (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY)) 717 goto unlock; 718 719 __br_set_forward_delay(br, t); 720 err = 0; 721 722 unlock: 723 spin_unlock_bh(&br->lock); 724 return err; 725 } 726