kernel/net/bridge/br_stp.c

   1 /*
   2  *      Spanning tree protocol; generic parts
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License
  10  *      as published by the Free Software Foundation; either version
  11  *      2 of the License, or (at your option) any later version.
  12  */
  13 #include <linux/kernel.h>
  14 #include <linux/rculist.h>
  15 #include <net/switchdev.h>
  16
  17 #include "br_private.h"
  18 #include "br_private_stp.h"
  19
  20 /* since time values in bpdu are in jiffies and then scaled (1/256)
  21  * before sending, make sure that is at least one STP tick.
  22  */
  23 #define MESSAGE_AGE_INCR        ((HZ / 256) + 1)
  24
  25 static const char *const br_port_state_names[] = {
  26         [BR_STATE_DISABLED] = "disabled",
  27         [BR_STATE_LISTENING] = "listening",
  28         [BR_STATE_LEARNING] = "learning",
  29         [BR_STATE_FORWARDING] = "forwarding",
  30         [BR_STATE_BLOCKING] = "blocking",
  31 };
  32
  33 void br_log_state(const struct net_bridge_port *p)
  34 {
  35         br_info(p->br, "port %u(%s) entered %s state\n",
  36                 (unsigned int) p->port_no, p->dev->name,
  37                 br_port_state_names[p->state]);
  38 }
  39
  40 void br_set_state(struct net_bridge_port *p, unsigned int state)
  41 {
  42         struct switchdev_attr attr = {
  43                 .id = SWITCHDEV_ATTR_ID_PORT_STP_STATE,
  44                 .flags = SWITCHDEV_F_DEFER,
  45                 .u.stp_state = state,
  46         };
  47         int err;
  48
  49         p->state = state;
  50         err = switchdev_port_attr_set(p->dev, &attr);
  51         if (err && err != -EOPNOTSUPP)
  52                 br_warn(p->br, "error setting offload STP state on port %u(%s)\n",
  53                                 (unsigned int) p->port_no, p->dev->name);
  54 }
  55
  56 /* called under bridge lock */
  57 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
  58 {
  59         struct net_bridge_port *p;
  60
  61         list_for_each_entry_rcu(p, &br->port_list, list) {
  62                 if (p->port_no == port_no)
  63                         return p;
  64         }
  65
  66         return NULL;
  67 }
  68
  69 /* called under bridge lock */
  70 static int br_should_become_root_port(const struct net_bridge_port *p,
  71                                       u16 root_port)
  72 {
  73         struct net_bridge *br;
  74         struct net_bridge_port *rp;
  75         int t;
  76
  77         br = p->br;
  78         if (p->state == BR_STATE_DISABLED ||
  79             br_is_designated_port(p))
  80                 return 0;
  81
  82         if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
  83                 return 0;
  84
  85         if (!root_port)
  86                 return 1;
  87
  88         rp = br_get_port(br, root_port);
  89
  90         t = memcmp(&p->designated_root, &rp->designated_root, 8);
  91         if (t < 0)
  92                 return 1;
  93         else if (t > 0)
  94                 return 0;
  95
  96         if (p->designated_cost + p->path_cost <
  97             rp->designated_cost + rp->path_cost)
  98                 return 1;
  99         else if (p->designated_cost + p->path_cost >
 100                  rp->designated_cost + rp->path_cost)
 101                 return 0;
 102
 103         t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
 104         if (t < 0)
 105                 return 1;
 106         else if (t > 0)
 107                 return 0;
 108
 109         if (p->designated_port < rp->designated_port)
 110                 return 1;
 111         else if (p->designated_port > rp->designated_port)
 112                 return 0;
 113
 114         if (p->port_id < rp->port_id)
 115                 return 1;
 116
 117         return 0;
 118 }
 119
 120 static void br_root_port_block(const struct net_bridge *br,
 121                                struct net_bridge_port *p)
 122 {
 123
 124         br_notice(br, "port %u(%s) tried to become root port (blocked)",
 125                   (unsigned int) p->port_no, p->dev->name);
 126
 127         br_set_state(p, BR_STATE_LISTENING);
 128         br_log_state(p);
 129         br_ifinfo_notify(RTM_NEWLINK, p);
 130
 131         if (br->forward_delay > 0)
 132                 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
 133 }
 134
 135 /* called under bridge lock */
 136 static void br_root_selection(struct net_bridge *br)
 137 {
 138         struct net_bridge_port *p;
 139         u16 root_port = 0;
 140
 141         list_for_each_entry(p, &br->port_list, list) {
 142                 if (!br_should_become_root_port(p, root_port))
 143                         continue;
 144
 145                 if (p->flags & BR_ROOT_BLOCK)
 146                         br_root_port_block(br, p);
 147                 else
 148                         root_port = p->port_no;
 149         }
 150
 151         br->root_port = root_port;
 152
 153         if (!root_port) {
 154                 br->designated_root = br->bridge_id;
 155                 br->root_path_cost = 0;
 156         } else {
 157                 p = br_get_port(br, root_port);
 158                 br->designated_root = p->designated_root;
 159                 br->root_path_cost = p->designated_cost + p->path_cost;
 160         }
 161 }
 162
 163 /* called under bridge lock */
 164 void br_become_root_bridge(struct net_bridge *br)
 165 {
 166         br->max_age = br->bridge_max_age;
 167         br->hello_time = br->bridge_hello_time;
 168         br->forward_delay = br->bridge_forward_delay;
 169         br_topology_change_detection(br);
 170         del_timer(&br->tcn_timer);
 171
 172         if (br->dev->flags & IFF_UP) {
 173                 br_config_bpdu_generation(br);
 174                 mod_timer(&br->hello_timer, jiffies + br->hello_time);
 175         }
 176 }
 177
 178 /* called under bridge lock */
 179 void br_transmit_config(struct net_bridge_port *p)
 180 {
 181         struct br_config_bpdu bpdu;
 182         struct net_bridge *br;
 183
 184         if (timer_pending(&p->hold_timer)) {
 185                 p->config_pending = 1;
 186                 return;
 187         }
 188
 189         br = p->br;
 190
 191         bpdu.topology_change = br->topology_change;
 192         bpdu.topology_change_ack = p->topology_change_ack;
 193         bpdu.root = br->designated_root;
 194         bpdu.root_path_cost = br->root_path_cost;
 195         bpdu.bridge_id = br->bridge_id;
 196         bpdu.port_id = p->port_id;
 197         if (br_is_root_bridge(br))
 198                 bpdu.message_age = 0;
 199         else {
 200                 struct net_bridge_port *root
 201                         = br_get_port(br, br->root_port);
 202                 bpdu.message_age = (jiffies - root->designated_age)
 203                         + MESSAGE_AGE_INCR;
 204         }
 205         bpdu.max_age = br->max_age;
 206         bpdu.hello_time = br->hello_time;
 207         bpdu.forward_delay = br->forward_delay;
 208
 209         if (bpdu.message_age < br->max_age) {
 210                 br_send_config_bpdu(p, &bpdu);
 211                 p->topology_change_ack = 0;
 212                 p->config_pending = 0;
 213                 if (p->br->stp_enabled == BR_KERNEL_STP)
 214                         mod_timer(&p->hold_timer,
 215                                   round_jiffies(jiffies + BR_HOLD_TIME));
 216         }
 217 }
 218
 219 /* called under bridge lock */
 220 static void br_record_config_information(struct net_bridge_port *p,
 221                                          const struct br_config_bpdu *bpdu)
 222 {
 223         p->designated_root = bpdu->root;
 224         p->designated_cost = bpdu->root_path_cost;
 225         p->designated_bridge = bpdu->bridge_id;
 226         p->designated_port = bpdu->port_id;
 227         p->designated_age = jiffies - bpdu->message_age;
 228
 229         mod_timer(&p->message_age_timer, jiffies
 230                   + (bpdu->max_age - bpdu->message_age));
 231 }
 232
 233 /* called under bridge lock */
 234 static void br_record_config_timeout_values(struct net_bridge *br,
 235                                             const struct br_config_bpdu *bpdu)
 236 {
 237         br->max_age = bpdu->max_age;
 238         br->hello_time = bpdu->hello_time;
 239         br->forward_delay = bpdu->forward_delay;
 240         br->topology_change = bpdu->topology_change;
 241 }
 242
 243 /* called under bridge lock */
 244 void br_transmit_tcn(struct net_bridge *br)
 245 {
 246         struct net_bridge_port *p;
 247
 248         p = br_get_port(br, br->root_port);
 249         if (p)
 250                 br_send_tcn_bpdu(p);
 251         else
 252                 br_notice(br, "root port %u not found for topology notice\n",
 253                           br->root_port);
 254 }
 255
 256 /* called under bridge lock */
 257 static int br_should_become_designated_port(const struct net_bridge_port *p)
 258 {
 259         struct net_bridge *br;
 260         int t;
 261
 262         br = p->br;
 263         if (br_is_designated_port(p))
 264                 return 1;
 265
 266         if (memcmp(&p->designated_root, &br->designated_root, 8))
 267                 return 1;
 268
 269         if (br->root_path_cost < p->designated_cost)
 270                 return 1;
 271         else if (br->root_path_cost > p->designated_cost)
 272                 return 0;
 273
 274         t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
 275         if (t < 0)
 276                 return 1;
 277         else if (t > 0)
 278                 return 0;
 279
 280         if (p->port_id < p->designated_port)
 281                 return 1;
 282
 283         return 0;
 284 }
 285
 286 /* called under bridge lock */
 287 static void br_designated_port_selection(struct net_bridge *br)
 288 {
 289         struct net_bridge_port *p;
 290
 291         list_for_each_entry(p, &br->port_list, list) {
 292                 if (p->state != BR_STATE_DISABLED &&
 293                     br_should_become_designated_port(p))
 294                         br_become_designated_port(p);
 295
 296         }
 297 }
 298
 299 /* called under bridge lock */
 300 static int br_supersedes_port_info(const struct net_bridge_port *p,
 301                                    const struct br_config_bpdu *bpdu)
 302 {
 303         int t;
 304
 305         t = memcmp(&bpdu->root, &p->designated_root, 8);
 306         if (t < 0)
 307                 return 1;
 308         else if (t > 0)
 309                 return 0;
 310
 311         if (bpdu->root_path_cost < p->designated_cost)
 312                 return 1;
 313         else if (bpdu->root_path_cost > p->designated_cost)
 314                 return 0;
 315
 316         t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
 317         if (t < 0)
 318                 return 1;
 319         else if (t > 0)
 320                 return 0;
 321
 322         if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
 323                 return 1;
 324
 325         if (bpdu->port_id <= p->designated_port)
 326                 return 1;
 327
 328         return 0;
 329 }
 330
 331 /* called under bridge lock */
 332 static void br_topology_change_acknowledged(struct net_bridge *br)
 333 {
 334         br->topology_change_detected = 0;
 335         del_timer(&br->tcn_timer);
 336 }
 337
 338 /* called under bridge lock */
 339 void br_topology_change_detection(struct net_bridge *br)
 340 {
 341         int isroot = br_is_root_bridge(br);
 342
 343         if (br->stp_enabled != BR_KERNEL_STP)
 344                 return;
 345
 346         br_info(br, "topology change detected, %s\n",
 347                 isroot ? "propagating" : "sending tcn bpdu");
 348
 349         if (isroot) {
 350                 br->topology_change = 1;
 351                 mod_timer(&br->topology_change_timer, jiffies
 352                           + br->bridge_forward_delay + br->bridge_max_age);
 353         } else if (!br->topology_change_detected) {
 354                 br_transmit_tcn(br);
 355                 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
 356         }
 357
 358         br->topology_change_detected = 1;
 359 }
 360
 361 /* called under bridge lock */
 362 void br_config_bpdu_generation(struct net_bridge *br)
 363 {
 364         struct net_bridge_port *p;
 365
 366         list_for_each_entry(p, &br->port_list, list) {
 367                 if (p->state != BR_STATE_DISABLED &&
 368                     br_is_designated_port(p))
 369                         br_transmit_config(p);
 370         }
 371 }
 372
 373 /* called under bridge lock */
 374 static void br_reply(struct net_bridge_port *p)
 375 {
 376         br_transmit_config(p);
 377 }
 378
 379 /* called under bridge lock */
 380 void br_configuration_update(struct net_bridge *br)
 381 {
 382         br_root_selection(br);
 383         br_designated_port_selection(br);
 384 }
 385
 386 /* called under bridge lock */
 387 void br_become_designated_port(struct net_bridge_port *p)
 388 {
 389         struct net_bridge *br;
 390
 391         br = p->br;
 392         p->designated_root = br->designated_root;
 393         p->designated_cost = br->root_path_cost;
 394         p->designated_bridge = br->bridge_id;
 395         p->designated_port = p->port_id;
 396 }
 397
 398
 399 /* called under bridge lock */
 400 static void br_make_blocking(struct net_bridge_port *p)
 401 {
 402         if (p->state != BR_STATE_DISABLED &&
 403             p->state != BR_STATE_BLOCKING) {
 404                 if (p->state == BR_STATE_FORWARDING ||
 405                     p->state == BR_STATE_LEARNING)
 406                         br_topology_change_detection(p->br);
 407
 408                 br_set_state(p, BR_STATE_BLOCKING);
 409                 br_log_state(p);
 410                 br_ifinfo_notify(RTM_NEWLINK, p);
 411
 412                 del_timer(&p->forward_delay_timer);
 413         }
 414 }
 415
 416 /* called under bridge lock */
 417 static void br_make_forwarding(struct net_bridge_port *p)
 418 {
 419         struct net_bridge *br = p->br;
 420
 421         if (p->state != BR_STATE_BLOCKING)
 422                 return;
 423
 424         if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) {
 425                 br_set_state(p, BR_STATE_FORWARDING);
 426                 br_topology_change_detection(br);
 427                 del_timer(&p->forward_delay_timer);
 428         } else if (br->stp_enabled == BR_KERNEL_STP)
 429                 br_set_state(p, BR_STATE_LISTENING);
 430         else
 431                 br_set_state(p, BR_STATE_LEARNING);
 432
 433         br_log_state(p);
 434         br_ifinfo_notify(RTM_NEWLINK, p);
 435
 436         if (br->forward_delay != 0)
 437                 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
 438 }
 439
 440 /* called under bridge lock */
 441 void br_port_state_selection(struct net_bridge *br)
 442 {
 443         struct net_bridge_port *p;
 444         unsigned int liveports = 0;
 445
 446         list_for_each_entry(p, &br->port_list, list) {
 447                 if (p->state == BR_STATE_DISABLED)
 448                         continue;
 449
 450                 /* Don't change port states if userspace is handling STP */
 451                 if (br->stp_enabled != BR_USER_STP) {
 452                         if (p->port_no == br->root_port) {
 453                                 p->config_pending = 0;
 454                                 p->topology_change_ack = 0;
 455                                 br_make_forwarding(p);
 456                         } else if (br_is_designated_port(p)) {
 457                                 del_timer(&p->message_age_timer);
 458                                 br_make_forwarding(p);
 459                         } else {
 460                                 p->config_pending = 0;
 461                                 p->topology_change_ack = 0;
 462                                 br_make_blocking(p);
 463                         }
 464                 }
 465
 466                 if (p->state != BR_STATE_BLOCKING)
 467                         br_multicast_enable_port(p);
 468                 /* Multicast is not disabled for the port when it goes in
 469                  * blocking state because the timers will expire and stop by
 470                  * themselves without sending more queries.
 471                  */
 472                 if (p->state == BR_STATE_FORWARDING)
 473                         ++liveports;
 474         }
 475
 476         if (liveports == 0)
 477                 netif_carrier_off(br->dev);
 478         else
 479                 netif_carrier_on(br->dev);
 480 }
 481
 482 /* called under bridge lock */
 483 static void br_topology_change_acknowledge(struct net_bridge_port *p)
 484 {
 485         p->topology_change_ack = 1;
 486         br_transmit_config(p);
 487 }
 488
 489 /* called under bridge lock */
 490 void br_received_config_bpdu(struct net_bridge_port *p,
 491                              const struct br_config_bpdu *bpdu)
 492 {
 493         struct net_bridge *br;
 494         int was_root;
 495
 496         br = p->br;
 497         was_root = br_is_root_bridge(br);
 498
 499         if (br_supersedes_port_info(p, bpdu)) {
 500                 br_record_config_information(p, bpdu);
 501                 br_configuration_update(br);
 502                 br_port_state_selection(br);
 503
 504                 if (!br_is_root_bridge(br) && was_root) {
 505                         del_timer(&br->hello_timer);
 506                         if (br->topology_change_detected) {
 507                                 del_timer(&br->topology_change_timer);
 508                                 br_transmit_tcn(br);
 509
 510                                 mod_timer(&br->tcn_timer,
 511                                           jiffies + br->bridge_hello_time);
 512                         }
 513                 }
 514
 515                 if (p->port_no == br->root_port) {
 516                         br_record_config_timeout_values(br, bpdu);
 517                         br_config_bpdu_generation(br);
 518                         if (bpdu->topology_change_ack)
 519                                 br_topology_change_acknowledged(br);
 520                 }
 521         } else if (br_is_designated_port(p)) {
 522                 br_reply(p);
 523         }
 524 }
 525
 526 /* called under bridge lock */
 527 void br_received_tcn_bpdu(struct net_bridge_port *p)
 528 {
 529         if (br_is_designated_port(p)) {
 530                 br_info(p->br, "port %u(%s) received tcn bpdu\n",
 531                         (unsigned int) p->port_no, p->dev->name);
 532
 533                 br_topology_change_detection(p->br);
 534                 br_topology_change_acknowledge(p);
 535         }
 536 }
 537
 538 /* Change bridge STP parameter */
 539 int br_set_hello_time(struct net_bridge *br, unsigned long val)
 540 {
 541         unsigned long t = clock_t_to_jiffies(val);
 542
 543         if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
 544                 return -ERANGE;
 545
 546         spin_lock_bh(&br->lock);
 547         br->bridge_hello_time = t;
 548         if (br_is_root_bridge(br))
 549                 br->hello_time = br->bridge_hello_time;
 550         spin_unlock_bh(&br->lock);
 551         return 0;
 552 }
 553
 554 int br_set_max_age(struct net_bridge *br, unsigned long val)
 555 {
 556         unsigned long t = clock_t_to_jiffies(val);
 557
 558         if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
 559                 return -ERANGE;
 560
 561         spin_lock_bh(&br->lock);
 562         br->bridge_max_age = t;
 563         if (br_is_root_bridge(br))
 564                 br->max_age = br->bridge_max_age;
 565         spin_unlock_bh(&br->lock);
 566         return 0;
 567
 568 }
 569
 570 /* Set time interval that dynamic forwarding entries live
 571  * For pure software bridge, allow values outside the 802.1
 572  * standard specification for special cases:
 573  *  0 - entry never ages (all permanant)
 574  *  1 - entry disappears (no persistance)
 575  *
 576  * Offloaded switch entries maybe more restrictive
 577  */
 578 int br_set_ageing_time(struct net_bridge *br, u32 ageing_time)
 579 {
 580         struct switchdev_attr attr = {
 581                 .id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME,
 582                 .flags = SWITCHDEV_F_SKIP_EOPNOTSUPP,
 583                 .u.ageing_time = ageing_time,
 584         };
 585         unsigned long t = clock_t_to_jiffies(ageing_time);
 586         int err;
 587
 588         err = switchdev_port_attr_set(br->dev, &attr);
 589         if (err && err != -EOPNOTSUPP)
 590                 return err;
 591
 592         br->ageing_time = t;
 593         mod_timer(&br->gc_timer, jiffies);
 594
 595         return 0;
 596 }
 597
 598 void __br_set_forward_delay(struct net_bridge *br, unsigned long t)
 599 {
 600         br->bridge_forward_delay = t;
 601         if (br_is_root_bridge(br))
 602                 br->forward_delay = br->bridge_forward_delay;
 603 }
 604
 605 int br_set_forward_delay(struct net_bridge *br, unsigned long val)
 606 {
 607         unsigned long t = clock_t_to_jiffies(val);
 608         int err = -ERANGE;
 609
 610         spin_lock_bh(&br->lock);
 611         if (br->stp_enabled != BR_NO_STP &&
 612             (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
 613                 goto unlock;
 614
 615         __br_set_forward_delay(br, t);
 616         err = 0;
 617
 618 unlock:
 619         spin_unlock_bh(&br->lock);
 620         return err;
 621 }