net/bridge/br_stp.c

   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 }