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                 mod_timer(&p->hold_timer,
 213                           round_jiffies(jiffies + BR_HOLD_TIME));
 214         }
 215 }
 216
 217 /* called under bridge lock */
 218 static void br_record_config_information(struct net_bridge_port *p,
 219                                          const struct br_config_bpdu *bpdu)
 220 {
 221         p->designated_root = bpdu->root;
 222         p->designated_cost = bpdu->root_path_cost;
 223         p->designated_bridge = bpdu->bridge_id;
 224         p->designated_port = bpdu->port_id;
 225         p->designated_age = jiffies - bpdu->message_age;
 226
 227         mod_timer(&p->message_age_timer, jiffies
 228                   + (bpdu->max_age - bpdu->message_age));
 229 }
 230
 231 /* called under bridge lock */
 232 static void br_record_config_timeout_values(struct net_bridge *br,
 233                                             const struct br_config_bpdu *bpdu)
 234 {
 235         br->max_age = bpdu->max_age;
 236         br->hello_time = bpdu->hello_time;
 237         br->forward_delay = bpdu->forward_delay;
 238         br->topology_change = bpdu->topology_change;
 239 }
 240
 241 /* called under bridge lock */
 242 void br_transmit_tcn(struct net_bridge *br)
 243 {
 244         struct net_bridge_port *p;
 245
 246         p = br_get_port(br, br->root_port);
 247         if (p)
 248                 br_send_tcn_bpdu(p);
 249         else
 250                 br_notice(br, "root port %u not found for topology notice\n",
 251                           br->root_port);
 252 }
 253
 254 /* called under bridge lock */
 255 static int br_should_become_designated_port(const struct net_bridge_port *p)
 256 {
 257         struct net_bridge *br;
 258         int t;
 259
 260         br = p->br;
 261         if (br_is_designated_port(p))
 262                 return 1;
 263
 264         if (memcmp(&p->designated_root, &br->designated_root, 8))
 265                 return 1;
 266
 267         if (br->root_path_cost < p->designated_cost)
 268                 return 1;
 269         else if (br->root_path_cost > p->designated_cost)
 270                 return 0;
 271
 272         t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
 273         if (t < 0)
 274                 return 1;
 275         else if (t > 0)
 276                 return 0;
 277
 278         if (p->port_id < p->designated_port)
 279                 return 1;
 280
 281         return 0;
 282 }
 283
 284 /* called under bridge lock */
 285 static void br_designated_port_selection(struct net_bridge *br)
 286 {
 287         struct net_bridge_port *p;
 288
 289         list_for_each_entry(p, &br->port_list, list) {
 290                 if (p->state != BR_STATE_DISABLED &&
 291                     br_should_become_designated_port(p))
 292                         br_become_designated_port(p);
 293
 294         }
 295 }
 296
 297 /* called under bridge lock */
 298 static int br_supersedes_port_info(const struct net_bridge_port *p,
 299                                    const struct br_config_bpdu *bpdu)
 300 {
 301         int t;
 302
 303         t = memcmp(&bpdu->root, &p->designated_root, 8);
 304         if (t < 0)
 305                 return 1;
 306         else if (t > 0)
 307                 return 0;
 308
 309         if (bpdu->root_path_cost < p->designated_cost)
 310                 return 1;
 311         else if (bpdu->root_path_cost > p->designated_cost)
 312                 return 0;
 313
 314         t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
 315         if (t < 0)
 316                 return 1;
 317         else if (t > 0)
 318                 return 0;
 319
 320         if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
 321                 return 1;
 322
 323         if (bpdu->port_id <= p->designated_port)
 324                 return 1;
 325
 326         return 0;
 327 }
 328
 329 /* called under bridge lock */
 330 static void br_topology_change_acknowledged(struct net_bridge *br)
 331 {
 332         br->topology_change_detected = 0;
 333         del_timer(&br->tcn_timer);
 334 }
 335
 336 /* called under bridge lock */
 337 void br_topology_change_detection(struct net_bridge *br)
 338 {
 339         int isroot = br_is_root_bridge(br);
 340
 341         if (br->stp_enabled != BR_KERNEL_STP)
 342                 return;
 343
 344         br_info(br, "topology change detected, %s\n",
 345                 isroot ? "propagating" : "sending tcn bpdu");
 346
 347         if (isroot) {
 348                 br->topology_change = 1;
 349                 mod_timer(&br->topology_change_timer, jiffies
 350                           + br->bridge_forward_delay + br->bridge_max_age);
 351         } else if (!br->topology_change_detected) {
 352                 br_transmit_tcn(br);
 353                 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
 354         }
 355
 356         br->topology_change_detected = 1;
 357 }
 358
 359 /* called under bridge lock */
 360 void br_config_bpdu_generation(struct net_bridge *br)
 361 {
 362         struct net_bridge_port *p;
 363
 364         list_for_each_entry(p, &br->port_list, list) {
 365                 if (p->state != BR_STATE_DISABLED &&
 366                     br_is_designated_port(p))
 367                         br_transmit_config(p);
 368         }
 369 }
 370
 371 /* called under bridge lock */
 372 static void br_reply(struct net_bridge_port *p)
 373 {
 374         br_transmit_config(p);
 375 }
 376
 377 /* called under bridge lock */
 378 void br_configuration_update(struct net_bridge *br)
 379 {
 380         br_root_selection(br);
 381         br_designated_port_selection(br);
 382 }
 383
 384 /* called under bridge lock */
 385 void br_become_designated_port(struct net_bridge_port *p)
 386 {
 387         struct net_bridge *br;
 388
 389         br = p->br;
 390         p->designated_root = br->designated_root;
 391         p->designated_cost = br->root_path_cost;
 392         p->designated_bridge = br->bridge_id;
 393         p->designated_port = p->port_id;
 394 }
 395
 396
 397 /* called under bridge lock */
 398 static void br_make_blocking(struct net_bridge_port *p)
 399 {
 400         if (p->state != BR_STATE_DISABLED &&
 401             p->state != BR_STATE_BLOCKING) {
 402                 if (p->state == BR_STATE_FORWARDING ||
 403                     p->state == BR_STATE_LEARNING)
 404                         br_topology_change_detection(p->br);
 405
 406                 br_set_state(p, BR_STATE_BLOCKING);
 407                 br_log_state(p);
 408                 br_ifinfo_notify(RTM_NEWLINK, p);
 409
 410                 del_timer(&p->forward_delay_timer);
 411         }
 412 }
 413
 414 /* called under bridge lock */
 415 static void br_make_forwarding(struct net_bridge_port *p)
 416 {
 417         struct net_bridge *br = p->br;
 418
 419         if (p->state != BR_STATE_BLOCKING)
 420                 return;
 421
 422         if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) {
 423                 br_set_state(p, BR_STATE_FORWARDING);
 424                 br_topology_change_detection(br);
 425                 del_timer(&p->forward_delay_timer);
 426         } else if (br->stp_enabled == BR_KERNEL_STP)
 427                 br_set_state(p, BR_STATE_LISTENING);
 428         else
 429                 br_set_state(p, BR_STATE_LEARNING);
 430
 431         br_log_state(p);
 432         br_ifinfo_notify(RTM_NEWLINK, p);
 433
 434         if (br->forward_delay != 0)
 435                 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
 436 }
 437
 438 /* called under bridge lock */
 439 void br_port_state_selection(struct net_bridge *br)
 440 {
 441         struct net_bridge_port *p;
 442         unsigned int liveports = 0;
 443
 444         list_for_each_entry(p, &br->port_list, list) {
 445                 if (p->state == BR_STATE_DISABLED)
 446                         continue;
 447
 448                 /* Don't change port states if userspace is handling STP */
 449                 if (br->stp_enabled != BR_USER_STP) {
 450                         if (p->port_no == br->root_port) {
 451                                 p->config_pending = 0;
 452                                 p->topology_change_ack = 0;
 453                                 br_make_forwarding(p);
 454                         } else if (br_is_designated_port(p)) {
 455                                 del_timer(&p->message_age_timer);
 456                                 br_make_forwarding(p);
 457                         } else {
 458                                 p->config_pending = 0;
 459                                 p->topology_change_ack = 0;
 460                                 br_make_blocking(p);
 461                         }
 462                 }
 463
 464                 if (p->state != BR_STATE_BLOCKING)
 465                         br_multicast_enable_port(p);
 466                 /* Multicast is not disabled for the port when it goes in
 467                  * blocking state because the timers will expire and stop by
 468                  * themselves without sending more queries.
 469                  */
 470                 if (p->state == BR_STATE_FORWARDING)
 471                         ++liveports;
 472         }
 473
 474         if (liveports == 0)
 475                 netif_carrier_off(br->dev);
 476         else
 477                 netif_carrier_on(br->dev);
 478 }
 479
 480 /* called under bridge lock */
 481 static void br_topology_change_acknowledge(struct net_bridge_port *p)
 482 {
 483         p->topology_change_ack = 1;
 484         br_transmit_config(p);
 485 }
 486
 487 /* called under bridge lock */
 488 void br_received_config_bpdu(struct net_bridge_port *p,
 489                              const struct br_config_bpdu *bpdu)
 490 {
 491         struct net_bridge *br;
 492         int was_root;
 493
 494         br = p->br;
 495         was_root = br_is_root_bridge(br);
 496
 497         if (br_supersedes_port_info(p, bpdu)) {
 498                 br_record_config_information(p, bpdu);
 499                 br_configuration_update(br);
 500                 br_port_state_selection(br);
 501
 502                 if (!br_is_root_bridge(br) && was_root) {
 503                         del_timer(&br->hello_timer);
 504                         if (br->topology_change_detected) {
 505                                 del_timer(&br->topology_change_timer);
 506                                 br_transmit_tcn(br);
 507
 508                                 mod_timer(&br->tcn_timer,
 509                                           jiffies + br->bridge_hello_time);
 510                         }
 511                 }
 512
 513                 if (p->port_no == br->root_port) {
 514                         br_record_config_timeout_values(br, bpdu);
 515                         br_config_bpdu_generation(br);
 516                         if (bpdu->topology_change_ack)
 517                                 br_topology_change_acknowledged(br);
 518                 }
 519         } else if (br_is_designated_port(p)) {
 520                 br_reply(p);
 521         }
 522 }
 523
 524 /* called under bridge lock */
 525 void br_received_tcn_bpdu(struct net_bridge_port *p)
 526 {
 527         if (br_is_designated_port(p)) {
 528                 br_info(p->br, "port %u(%s) received tcn bpdu\n",
 529                         (unsigned int) p->port_no, p->dev->name);
 530
 531                 br_topology_change_detection(p->br);
 532                 br_topology_change_acknowledge(p);
 533         }
 534 }
 535
 536 /* Change bridge STP parameter */
 537 int br_set_hello_time(struct net_bridge *br, unsigned long val)
 538 {
 539         unsigned long t = clock_t_to_jiffies(val);
 540
 541         if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
 542                 return -ERANGE;
 543
 544         spin_lock_bh(&br->lock);
 545         br->bridge_hello_time = t;
 546         if (br_is_root_bridge(br))
 547                 br->hello_time = br->bridge_hello_time;
 548         spin_unlock_bh(&br->lock);
 549         return 0;
 550 }
 551
 552 int br_set_max_age(struct net_bridge *br, unsigned long val)
 553 {
 554         unsigned long t = clock_t_to_jiffies(val);
 555
 556         if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
 557                 return -ERANGE;
 558
 559         spin_lock_bh(&br->lock);
 560         br->bridge_max_age = t;
 561         if (br_is_root_bridge(br))
 562                 br->max_age = br->bridge_max_age;
 563         spin_unlock_bh(&br->lock);
 564         return 0;
 565
 566 }
 567
 568 void __br_set_forward_delay(struct net_bridge *br, unsigned long t)
 569 {
 570         br->bridge_forward_delay = t;
 571         if (br_is_root_bridge(br))
 572                 br->forward_delay = br->bridge_forward_delay;
 573 }
 574
 575 int br_set_forward_delay(struct net_bridge *br, unsigned long val)
 576 {
 577         unsigned long t = clock_t_to_jiffies(val);
 578         int err = -ERANGE;
 579
 580         spin_lock_bh(&br->lock);
 581         if (br->stp_enabled != BR_NO_STP &&
 582             (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
 583                 goto unlock;
 584
 585         __br_set_forward_delay(br, t);
 586         err = 0;
 587
 588 unlock:
 589         spin_unlock_bh(&br->lock);
 590         return err;
 591 }