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