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