1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Spanning tree protocol; generic parts
4 * Linux ethernet bridge
7 * Lennert Buytenhek <buytenh@gnu.org>
9 #include <linux/kernel.h>
10 #include <linux/rculist.h>
11 #include <net/switchdev.h>
13 #include "br_private.h"
14 #include "br_private_stp.h"
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.
19 #define MESSAGE_AGE_INCR ((HZ / 256) + 1)
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",
29 void br_set_state(struct net_bridge_port *p, unsigned int state)
31 struct switchdev_attr attr = {
33 .id = SWITCHDEV_ATTR_ID_PORT_STP_STATE,
34 .flags = SWITCHDEV_F_DEFER,
40 err = switchdev_port_attr_set(p->dev, &attr);
41 if (err && err != -EOPNOTSUPP)
42 br_warn(p->br, "error setting offload STP state on port %u(%s)\n",
43 (unsigned int) p->port_no, p->dev->name);
45 br_info(p->br, "port %u(%s) entered %s state\n",
46 (unsigned int) p->port_no, p->dev->name,
47 br_port_state_names[p->state]);
50 /* called under bridge lock */
51 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
53 struct net_bridge_port *p;
55 list_for_each_entry_rcu(p, &br->port_list, list) {
56 if (p->port_no == port_no)
63 /* called under bridge lock */
64 static int br_should_become_root_port(const struct net_bridge_port *p,
67 struct net_bridge *br;
68 struct net_bridge_port *rp;
72 if (p->state == BR_STATE_DISABLED ||
73 br_is_designated_port(p))
76 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
82 rp = br_get_port(br, root_port);
84 t = memcmp(&p->designated_root, &rp->designated_root, 8);
90 if (p->designated_cost + p->path_cost <
91 rp->designated_cost + rp->path_cost)
93 else if (p->designated_cost + p->path_cost >
94 rp->designated_cost + rp->path_cost)
97 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
103 if (p->designated_port < rp->designated_port)
105 else if (p->designated_port > rp->designated_port)
108 if (p->port_id < rp->port_id)
114 static void br_root_port_block(const struct net_bridge *br,
115 struct net_bridge_port *p)
118 br_notice(br, "port %u(%s) tried to become root port (blocked)",
119 (unsigned int) p->port_no, p->dev->name);
121 br_set_state(p, BR_STATE_LISTENING);
122 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
124 if (br->forward_delay > 0)
125 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
128 /* called under bridge lock */
129 static void br_root_selection(struct net_bridge *br)
131 struct net_bridge_port *p;
134 list_for_each_entry(p, &br->port_list, list) {
135 if (!br_should_become_root_port(p, root_port))
138 if (p->flags & BR_ROOT_BLOCK)
139 br_root_port_block(br, p);
141 root_port = p->port_no;
144 br->root_port = root_port;
147 br->designated_root = br->bridge_id;
148 br->root_path_cost = 0;
150 p = br_get_port(br, root_port);
151 br->designated_root = p->designated_root;
152 br->root_path_cost = p->designated_cost + p->path_cost;
156 /* called under bridge lock */
157 void br_become_root_bridge(struct net_bridge *br)
159 br->max_age = br->bridge_max_age;
160 br->hello_time = br->bridge_hello_time;
161 br->forward_delay = br->bridge_forward_delay;
162 br_topology_change_detection(br);
163 del_timer(&br->tcn_timer);
165 if (br->dev->flags & IFF_UP) {
166 br_config_bpdu_generation(br);
167 mod_timer(&br->hello_timer, jiffies + br->hello_time);
171 /* called under bridge lock */
172 void br_transmit_config(struct net_bridge_port *p)
174 struct br_config_bpdu bpdu;
175 struct net_bridge *br;
177 if (timer_pending(&p->hold_timer)) {
178 p->config_pending = 1;
184 bpdu.topology_change = br->topology_change;
185 bpdu.topology_change_ack = p->topology_change_ack;
186 bpdu.root = br->designated_root;
187 bpdu.root_path_cost = br->root_path_cost;
188 bpdu.bridge_id = br->bridge_id;
189 bpdu.port_id = p->port_id;
190 if (br_is_root_bridge(br))
191 bpdu.message_age = 0;
193 struct net_bridge_port *root
194 = br_get_port(br, br->root_port);
195 bpdu.message_age = (jiffies - root->designated_age)
198 bpdu.max_age = br->max_age;
199 bpdu.hello_time = br->hello_time;
200 bpdu.forward_delay = br->forward_delay;
202 if (bpdu.message_age < br->max_age) {
203 br_send_config_bpdu(p, &bpdu);
204 p->topology_change_ack = 0;
205 p->config_pending = 0;
206 if (p->br->stp_enabled == BR_KERNEL_STP)
207 mod_timer(&p->hold_timer,
208 round_jiffies(jiffies + BR_HOLD_TIME));
212 /* called under bridge lock */
213 static void br_record_config_information(struct net_bridge_port *p,
214 const struct br_config_bpdu *bpdu)
216 p->designated_root = bpdu->root;
217 p->designated_cost = bpdu->root_path_cost;
218 p->designated_bridge = bpdu->bridge_id;
219 p->designated_port = bpdu->port_id;
220 p->designated_age = jiffies - bpdu->message_age;
222 mod_timer(&p->message_age_timer, jiffies
223 + (bpdu->max_age - bpdu->message_age));
226 /* called under bridge lock */
227 static void br_record_config_timeout_values(struct net_bridge *br,
228 const struct br_config_bpdu *bpdu)
230 br->max_age = bpdu->max_age;
231 br->hello_time = bpdu->hello_time;
232 br->forward_delay = bpdu->forward_delay;
233 __br_set_topology_change(br, bpdu->topology_change);
236 /* called under bridge lock */
237 void br_transmit_tcn(struct net_bridge *br)
239 struct net_bridge_port *p;
241 p = br_get_port(br, br->root_port);
245 br_notice(br, "root port %u not found for topology notice\n",
249 /* called under bridge lock */
250 static int br_should_become_designated_port(const struct net_bridge_port *p)
252 struct net_bridge *br;
256 if (br_is_designated_port(p))
259 if (memcmp(&p->designated_root, &br->designated_root, 8))
262 if (br->root_path_cost < p->designated_cost)
264 else if (br->root_path_cost > p->designated_cost)
267 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
273 if (p->port_id < p->designated_port)
279 /* called under bridge lock */
280 static void br_designated_port_selection(struct net_bridge *br)
282 struct net_bridge_port *p;
284 list_for_each_entry(p, &br->port_list, list) {
285 if (p->state != BR_STATE_DISABLED &&
286 br_should_become_designated_port(p))
287 br_become_designated_port(p);
292 /* called under bridge lock */
293 static int br_supersedes_port_info(const struct net_bridge_port *p,
294 const struct br_config_bpdu *bpdu)
298 t = memcmp(&bpdu->root, &p->designated_root, 8);
304 if (bpdu->root_path_cost < p->designated_cost)
306 else if (bpdu->root_path_cost > p->designated_cost)
309 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
315 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
318 if (bpdu->port_id <= p->designated_port)
324 /* called under bridge lock */
325 static void br_topology_change_acknowledged(struct net_bridge *br)
327 br->topology_change_detected = 0;
328 del_timer(&br->tcn_timer);
331 /* called under bridge lock */
332 void br_topology_change_detection(struct net_bridge *br)
334 int isroot = br_is_root_bridge(br);
336 if (br->stp_enabled != BR_KERNEL_STP)
339 br_info(br, "topology change detected, %s\n",
340 isroot ? "propagating" : "sending tcn bpdu");
343 __br_set_topology_change(br, 1);
344 mod_timer(&br->topology_change_timer, jiffies
345 + br->bridge_forward_delay + br->bridge_max_age);
346 } else if (!br->topology_change_detected) {
348 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
351 br->topology_change_detected = 1;
354 /* called under bridge lock */
355 void br_config_bpdu_generation(struct net_bridge *br)
357 struct net_bridge_port *p;
359 list_for_each_entry(p, &br->port_list, list) {
360 if (p->state != BR_STATE_DISABLED &&
361 br_is_designated_port(p))
362 br_transmit_config(p);
366 /* called under bridge lock */
367 static void br_reply(struct net_bridge_port *p)
369 br_transmit_config(p);
372 /* called under bridge lock */
373 void br_configuration_update(struct net_bridge *br)
375 br_root_selection(br);
376 br_designated_port_selection(br);
379 /* called under bridge lock */
380 void br_become_designated_port(struct net_bridge_port *p)
382 struct net_bridge *br;
385 p->designated_root = br->designated_root;
386 p->designated_cost = br->root_path_cost;
387 p->designated_bridge = br->bridge_id;
388 p->designated_port = p->port_id;
392 /* called under bridge lock */
393 static void br_make_blocking(struct net_bridge_port *p)
395 if (p->state != BR_STATE_DISABLED &&
396 p->state != BR_STATE_BLOCKING) {
397 if (p->state == BR_STATE_FORWARDING ||
398 p->state == BR_STATE_LEARNING)
399 br_topology_change_detection(p->br);
401 br_set_state(p, BR_STATE_BLOCKING);
402 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
404 del_timer(&p->forward_delay_timer);
408 /* called under bridge lock */
409 static void br_make_forwarding(struct net_bridge_port *p)
411 struct net_bridge *br = p->br;
413 if (p->state != BR_STATE_BLOCKING)
416 if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) {
417 br_set_state(p, BR_STATE_FORWARDING);
418 br_topology_change_detection(br);
419 del_timer(&p->forward_delay_timer);
420 } else if (br->stp_enabled == BR_KERNEL_STP)
421 br_set_state(p, BR_STATE_LISTENING);
423 br_set_state(p, BR_STATE_LEARNING);
425 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
427 if (br->forward_delay != 0)
428 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
431 /* called under bridge lock */
432 void br_port_state_selection(struct net_bridge *br)
434 struct net_bridge_port *p;
435 unsigned int liveports = 0;
437 list_for_each_entry(p, &br->port_list, list) {
438 if (p->state == BR_STATE_DISABLED)
441 /* Don't change port states if userspace is handling STP */
442 if (br->stp_enabled != BR_USER_STP) {
443 if (p->port_no == br->root_port) {
444 p->config_pending = 0;
445 p->topology_change_ack = 0;
446 br_make_forwarding(p);
447 } else if (br_is_designated_port(p)) {
448 del_timer(&p->message_age_timer);
449 br_make_forwarding(p);
451 p->config_pending = 0;
452 p->topology_change_ack = 0;
457 if (p->state != BR_STATE_BLOCKING)
458 br_multicast_enable_port(p);
459 /* Multicast is not disabled for the port when it goes in
460 * blocking state because the timers will expire and stop by
461 * themselves without sending more queries.
463 if (p->state == BR_STATE_FORWARDING)
468 netif_carrier_off(br->dev);
470 netif_carrier_on(br->dev);
473 /* called under bridge lock */
474 static void br_topology_change_acknowledge(struct net_bridge_port *p)
476 p->topology_change_ack = 1;
477 br_transmit_config(p);
480 /* called under bridge lock */
481 void br_received_config_bpdu(struct net_bridge_port *p,
482 const struct br_config_bpdu *bpdu)
484 struct net_bridge *br;
488 was_root = br_is_root_bridge(br);
490 if (br_supersedes_port_info(p, bpdu)) {
491 br_record_config_information(p, bpdu);
492 br_configuration_update(br);
493 br_port_state_selection(br);
495 if (!br_is_root_bridge(br) && was_root) {
496 del_timer(&br->hello_timer);
497 if (br->topology_change_detected) {
498 del_timer(&br->topology_change_timer);
501 mod_timer(&br->tcn_timer,
502 jiffies + br->bridge_hello_time);
506 if (p->port_no == br->root_port) {
507 br_record_config_timeout_values(br, bpdu);
508 br_config_bpdu_generation(br);
509 if (bpdu->topology_change_ack)
510 br_topology_change_acknowledged(br);
512 } else if (br_is_designated_port(p)) {
517 /* called under bridge lock */
518 void br_received_tcn_bpdu(struct net_bridge_port *p)
520 if (br_is_designated_port(p)) {
521 br_info(p->br, "port %u(%s) received tcn bpdu\n",
522 (unsigned int) p->port_no, p->dev->name);
524 br_topology_change_detection(p->br);
525 br_topology_change_acknowledge(p);
529 /* Change bridge STP parameter */
530 int br_set_hello_time(struct net_bridge *br, unsigned long val)
532 unsigned long t = clock_t_to_jiffies(val);
534 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
537 spin_lock_bh(&br->lock);
538 br->bridge_hello_time = t;
539 if (br_is_root_bridge(br))
540 br->hello_time = br->bridge_hello_time;
541 spin_unlock_bh(&br->lock);
545 int br_set_max_age(struct net_bridge *br, unsigned long val)
547 unsigned long t = clock_t_to_jiffies(val);
549 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
552 spin_lock_bh(&br->lock);
553 br->bridge_max_age = t;
554 if (br_is_root_bridge(br))
555 br->max_age = br->bridge_max_age;
556 spin_unlock_bh(&br->lock);
561 /* called under bridge lock */
562 int __set_ageing_time(struct net_device *dev, unsigned long t)
564 struct switchdev_attr attr = {
566 .id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME,
567 .flags = SWITCHDEV_F_SKIP_EOPNOTSUPP | SWITCHDEV_F_DEFER,
568 .u.ageing_time = jiffies_to_clock_t(t),
572 err = switchdev_port_attr_set(dev, &attr);
573 if (err && err != -EOPNOTSUPP)
579 /* Set time interval that dynamic forwarding entries live
580 * For pure software bridge, allow values outside the 802.1
581 * standard specification for special cases:
582 * 0 - entry never ages (all permanant)
583 * 1 - entry disappears (no persistance)
585 * Offloaded switch entries maybe more restrictive
587 int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time)
589 unsigned long t = clock_t_to_jiffies(ageing_time);
592 err = __set_ageing_time(br->dev, t);
596 spin_lock_bh(&br->lock);
597 br->bridge_ageing_time = t;
599 spin_unlock_bh(&br->lock);
601 mod_delayed_work(system_long_wq, &br->gc_work, 0);
606 /* called under bridge lock */
607 void __br_set_topology_change(struct net_bridge *br, unsigned char val)
612 if (br->stp_enabled == BR_KERNEL_STP && br->topology_change != val) {
613 /* On topology change, set the bridge ageing time to twice the
614 * forward delay. Otherwise, restore its default ageing time.
618 t = 2 * br->forward_delay;
619 br_debug(br, "decreasing ageing time to %lu\n", t);
621 t = br->bridge_ageing_time;
622 br_debug(br, "restoring ageing time to %lu\n", t);
625 err = __set_ageing_time(br->dev, t);
627 br_warn(br, "error offloading ageing time\n");
632 br->topology_change = val;
635 void __br_set_forward_delay(struct net_bridge *br, unsigned long t)
637 br->bridge_forward_delay = t;
638 if (br_is_root_bridge(br))
639 br->forward_delay = br->bridge_forward_delay;
642 int br_set_forward_delay(struct net_bridge *br, unsigned long val)
644 unsigned long t = clock_t_to_jiffies(val);
647 spin_lock_bh(&br->lock);
648 if (br->stp_enabled != BR_NO_STP &&
649 (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
652 __br_set_forward_delay(br, t);
656 spin_unlock_bh(&br->lock);