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