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,
39 /* Don't change the state of the ports if they are driven by a different
42 if (p->flags & BR_MRP_AWARE)
46 err = switchdev_port_attr_set(p->dev, &attr);
47 if (err && err != -EOPNOTSUPP)
48 br_warn(p->br, "error setting offload STP state on port %u(%s)\n",
49 (unsigned int) p->port_no, p->dev->name);
51 br_info(p->br, "port %u(%s) entered %s state\n",
52 (unsigned int) p->port_no, p->dev->name,
53 br_port_state_names[p->state]);
55 if (p->br->stp_enabled == BR_KERNEL_STP) {
57 case BR_STATE_BLOCKING:
58 p->stp_xstats.transition_blk++;
60 case BR_STATE_FORWARDING:
61 p->stp_xstats.transition_fwd++;
67 /* called under bridge lock */
68 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
70 struct net_bridge_port *p;
72 list_for_each_entry_rcu(p, &br->port_list, list,
73 lockdep_is_held(&br->lock)) {
74 if (p->port_no == port_no)
81 /* called under bridge lock */
82 static int br_should_become_root_port(const struct net_bridge_port *p,
85 struct net_bridge *br;
86 struct net_bridge_port *rp;
90 if (p->state == BR_STATE_DISABLED ||
91 br_is_designated_port(p))
94 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
100 rp = br_get_port(br, root_port);
102 t = memcmp(&p->designated_root, &rp->designated_root, 8);
108 if (p->designated_cost + p->path_cost <
109 rp->designated_cost + rp->path_cost)
111 else if (p->designated_cost + p->path_cost >
112 rp->designated_cost + rp->path_cost)
115 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
121 if (p->designated_port < rp->designated_port)
123 else if (p->designated_port > rp->designated_port)
126 if (p->port_id < rp->port_id)
132 static void br_root_port_block(const struct net_bridge *br,
133 struct net_bridge_port *p)
136 br_notice(br, "port %u(%s) tried to become root port (blocked)",
137 (unsigned int) p->port_no, p->dev->name);
139 br_set_state(p, BR_STATE_LISTENING);
140 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
142 if (br->forward_delay > 0)
143 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
146 /* called under bridge lock */
147 static void br_root_selection(struct net_bridge *br)
149 struct net_bridge_port *p;
152 list_for_each_entry(p, &br->port_list, list) {
153 if (!br_should_become_root_port(p, root_port))
156 if (p->flags & BR_ROOT_BLOCK)
157 br_root_port_block(br, p);
159 root_port = p->port_no;
162 br->root_port = root_port;
165 br->designated_root = br->bridge_id;
166 br->root_path_cost = 0;
168 p = br_get_port(br, root_port);
169 br->designated_root = p->designated_root;
170 br->root_path_cost = p->designated_cost + p->path_cost;
174 /* called under bridge lock */
175 void br_become_root_bridge(struct net_bridge *br)
177 br->max_age = br->bridge_max_age;
178 br->hello_time = br->bridge_hello_time;
179 br->forward_delay = br->bridge_forward_delay;
180 br_topology_change_detection(br);
181 del_timer(&br->tcn_timer);
183 if (br->dev->flags & IFF_UP) {
184 br_config_bpdu_generation(br);
185 mod_timer(&br->hello_timer, jiffies + br->hello_time);
189 /* called under bridge lock */
190 void br_transmit_config(struct net_bridge_port *p)
192 struct br_config_bpdu bpdu;
193 struct net_bridge *br;
195 if (timer_pending(&p->hold_timer)) {
196 p->config_pending = 1;
202 bpdu.topology_change = br->topology_change;
203 bpdu.topology_change_ack = p->topology_change_ack;
204 bpdu.root = br->designated_root;
205 bpdu.root_path_cost = br->root_path_cost;
206 bpdu.bridge_id = br->bridge_id;
207 bpdu.port_id = p->port_id;
208 if (br_is_root_bridge(br))
209 bpdu.message_age = 0;
211 struct net_bridge_port *root
212 = br_get_port(br, br->root_port);
213 bpdu.message_age = (jiffies - root->designated_age)
216 bpdu.max_age = br->max_age;
217 bpdu.hello_time = br->hello_time;
218 bpdu.forward_delay = br->forward_delay;
220 if (bpdu.message_age < br->max_age) {
221 br_send_config_bpdu(p, &bpdu);
222 p->topology_change_ack = 0;
223 p->config_pending = 0;
224 if (p->br->stp_enabled == BR_KERNEL_STP)
225 mod_timer(&p->hold_timer,
226 round_jiffies(jiffies + BR_HOLD_TIME));
230 /* called under bridge lock */
231 static void br_record_config_information(struct net_bridge_port *p,
232 const struct br_config_bpdu *bpdu)
234 p->designated_root = bpdu->root;
235 p->designated_cost = bpdu->root_path_cost;
236 p->designated_bridge = bpdu->bridge_id;
237 p->designated_port = bpdu->port_id;
238 p->designated_age = jiffies - bpdu->message_age;
240 mod_timer(&p->message_age_timer, jiffies
241 + (bpdu->max_age - bpdu->message_age));
244 /* called under bridge lock */
245 static void br_record_config_timeout_values(struct net_bridge *br,
246 const struct br_config_bpdu *bpdu)
248 br->max_age = bpdu->max_age;
249 br->hello_time = bpdu->hello_time;
250 br->forward_delay = bpdu->forward_delay;
251 __br_set_topology_change(br, bpdu->topology_change);
254 /* called under bridge lock */
255 void br_transmit_tcn(struct net_bridge *br)
257 struct net_bridge_port *p;
259 p = br_get_port(br, br->root_port);
263 br_notice(br, "root port %u not found for topology notice\n",
267 /* called under bridge lock */
268 static int br_should_become_designated_port(const struct net_bridge_port *p)
270 struct net_bridge *br;
274 if (br_is_designated_port(p))
277 if (memcmp(&p->designated_root, &br->designated_root, 8))
280 if (br->root_path_cost < p->designated_cost)
282 else if (br->root_path_cost > p->designated_cost)
285 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
291 if (p->port_id < p->designated_port)
297 /* called under bridge lock */
298 static void br_designated_port_selection(struct net_bridge *br)
300 struct net_bridge_port *p;
302 list_for_each_entry(p, &br->port_list, list) {
303 if (p->state != BR_STATE_DISABLED &&
304 br_should_become_designated_port(p))
305 br_become_designated_port(p);
310 /* called under bridge lock */
311 static int br_supersedes_port_info(const struct net_bridge_port *p,
312 const struct br_config_bpdu *bpdu)
316 t = memcmp(&bpdu->root, &p->designated_root, 8);
322 if (bpdu->root_path_cost < p->designated_cost)
324 else if (bpdu->root_path_cost > p->designated_cost)
327 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
333 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
336 if (bpdu->port_id <= p->designated_port)
342 /* called under bridge lock */
343 static void br_topology_change_acknowledged(struct net_bridge *br)
345 br->topology_change_detected = 0;
346 del_timer(&br->tcn_timer);
349 /* called under bridge lock */
350 void br_topology_change_detection(struct net_bridge *br)
352 int isroot = br_is_root_bridge(br);
354 if (br->stp_enabled != BR_KERNEL_STP)
357 br_info(br, "topology change detected, %s\n",
358 isroot ? "propagating" : "sending tcn bpdu");
361 __br_set_topology_change(br, 1);
362 mod_timer(&br->topology_change_timer, jiffies
363 + br->bridge_forward_delay + br->bridge_max_age);
364 } else if (!br->topology_change_detected) {
366 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
369 br->topology_change_detected = 1;
372 /* called under bridge lock */
373 void br_config_bpdu_generation(struct net_bridge *br)
375 struct net_bridge_port *p;
377 list_for_each_entry(p, &br->port_list, list) {
378 if (p->state != BR_STATE_DISABLED &&
379 br_is_designated_port(p))
380 br_transmit_config(p);
384 /* called under bridge lock */
385 static void br_reply(struct net_bridge_port *p)
387 br_transmit_config(p);
390 /* called under bridge lock */
391 void br_configuration_update(struct net_bridge *br)
393 br_root_selection(br);
394 br_designated_port_selection(br);
397 /* called under bridge lock */
398 void br_become_designated_port(struct net_bridge_port *p)
400 struct net_bridge *br;
403 p->designated_root = br->designated_root;
404 p->designated_cost = br->root_path_cost;
405 p->designated_bridge = br->bridge_id;
406 p->designated_port = p->port_id;
410 /* called under bridge lock */
411 static void br_make_blocking(struct net_bridge_port *p)
413 if (p->state != BR_STATE_DISABLED &&
414 p->state != BR_STATE_BLOCKING) {
415 if (p->state == BR_STATE_FORWARDING ||
416 p->state == BR_STATE_LEARNING)
417 br_topology_change_detection(p->br);
419 br_set_state(p, BR_STATE_BLOCKING);
420 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
422 del_timer(&p->forward_delay_timer);
426 /* called under bridge lock */
427 static void br_make_forwarding(struct net_bridge_port *p)
429 struct net_bridge *br = p->br;
431 if (p->state != BR_STATE_BLOCKING)
434 if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) {
435 br_set_state(p, BR_STATE_FORWARDING);
436 br_topology_change_detection(br);
437 del_timer(&p->forward_delay_timer);
438 } else if (br->stp_enabled == BR_KERNEL_STP)
439 br_set_state(p, BR_STATE_LISTENING);
441 br_set_state(p, BR_STATE_LEARNING);
443 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
445 if (br->forward_delay != 0)
446 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
449 /* called under bridge lock */
450 void br_port_state_selection(struct net_bridge *br)
452 struct net_bridge_port *p;
453 unsigned int liveports = 0;
455 list_for_each_entry(p, &br->port_list, list) {
456 if (p->state == BR_STATE_DISABLED)
459 /* Don't change port states if userspace is handling STP */
460 if (br->stp_enabled != BR_USER_STP) {
461 if (p->port_no == br->root_port) {
462 p->config_pending = 0;
463 p->topology_change_ack = 0;
464 br_make_forwarding(p);
465 } else if (br_is_designated_port(p)) {
466 del_timer(&p->message_age_timer);
467 br_make_forwarding(p);
469 p->config_pending = 0;
470 p->topology_change_ack = 0;
475 if (p->state != BR_STATE_BLOCKING)
476 br_multicast_enable_port(p);
477 /* Multicast is not disabled for the port when it goes in
478 * blocking state because the timers will expire and stop by
479 * themselves without sending more queries.
481 if (p->state == BR_STATE_FORWARDING)
486 netif_carrier_off(br->dev);
488 netif_carrier_on(br->dev);
491 /* called under bridge lock */
492 static void br_topology_change_acknowledge(struct net_bridge_port *p)
494 p->topology_change_ack = 1;
495 br_transmit_config(p);
498 /* called under bridge lock */
499 void br_received_config_bpdu(struct net_bridge_port *p,
500 const struct br_config_bpdu *bpdu)
502 struct net_bridge *br;
505 p->stp_xstats.rx_bpdu++;
508 was_root = br_is_root_bridge(br);
510 if (br_supersedes_port_info(p, bpdu)) {
511 br_record_config_information(p, bpdu);
512 br_configuration_update(br);
513 br_port_state_selection(br);
515 if (!br_is_root_bridge(br) && was_root) {
516 del_timer(&br->hello_timer);
517 if (br->topology_change_detected) {
518 del_timer(&br->topology_change_timer);
521 mod_timer(&br->tcn_timer,
522 jiffies + br->bridge_hello_time);
526 if (p->port_no == br->root_port) {
527 br_record_config_timeout_values(br, bpdu);
528 br_config_bpdu_generation(br);
529 if (bpdu->topology_change_ack)
530 br_topology_change_acknowledged(br);
532 } else if (br_is_designated_port(p)) {
537 /* called under bridge lock */
538 void br_received_tcn_bpdu(struct net_bridge_port *p)
540 p->stp_xstats.rx_tcn++;
542 if (br_is_designated_port(p)) {
543 br_info(p->br, "port %u(%s) received tcn bpdu\n",
544 (unsigned int) p->port_no, p->dev->name);
546 br_topology_change_detection(p->br);
547 br_topology_change_acknowledge(p);
551 /* Change bridge STP parameter */
552 int br_set_hello_time(struct net_bridge *br, unsigned long val)
554 unsigned long t = clock_t_to_jiffies(val);
556 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
559 spin_lock_bh(&br->lock);
560 br->bridge_hello_time = t;
561 if (br_is_root_bridge(br))
562 br->hello_time = br->bridge_hello_time;
563 spin_unlock_bh(&br->lock);
567 int br_set_max_age(struct net_bridge *br, unsigned long val)
569 unsigned long t = clock_t_to_jiffies(val);
571 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
574 spin_lock_bh(&br->lock);
575 br->bridge_max_age = t;
576 if (br_is_root_bridge(br))
577 br->max_age = br->bridge_max_age;
578 spin_unlock_bh(&br->lock);
583 /* called under bridge lock */
584 int __set_ageing_time(struct net_device *dev, unsigned long t)
586 struct switchdev_attr attr = {
588 .id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME,
589 .flags = SWITCHDEV_F_SKIP_EOPNOTSUPP | SWITCHDEV_F_DEFER,
590 .u.ageing_time = jiffies_to_clock_t(t),
594 err = switchdev_port_attr_set(dev, &attr);
595 if (err && err != -EOPNOTSUPP)
601 /* Set time interval that dynamic forwarding entries live
602 * For pure software bridge, allow values outside the 802.1
603 * standard specification for special cases:
604 * 0 - entry never ages (all permanant)
605 * 1 - entry disappears (no persistance)
607 * Offloaded switch entries maybe more restrictive
609 int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time)
611 unsigned long t = clock_t_to_jiffies(ageing_time);
614 err = __set_ageing_time(br->dev, t);
618 spin_lock_bh(&br->lock);
619 br->bridge_ageing_time = t;
621 spin_unlock_bh(&br->lock);
623 mod_delayed_work(system_long_wq, &br->gc_work, 0);
628 /* called under bridge lock */
629 void __br_set_topology_change(struct net_bridge *br, unsigned char val)
634 if (br->stp_enabled == BR_KERNEL_STP && br->topology_change != val) {
635 /* On topology change, set the bridge ageing time to twice the
636 * forward delay. Otherwise, restore its default ageing time.
640 t = 2 * br->forward_delay;
641 br_debug(br, "decreasing ageing time to %lu\n", t);
643 t = br->bridge_ageing_time;
644 br_debug(br, "restoring ageing time to %lu\n", t);
647 err = __set_ageing_time(br->dev, t);
649 br_warn(br, "error offloading ageing time\n");
654 br->topology_change = val;
657 void __br_set_forward_delay(struct net_bridge *br, unsigned long t)
659 br->bridge_forward_delay = t;
660 if (br_is_root_bridge(br))
661 br->forward_delay = br->bridge_forward_delay;
664 int br_set_forward_delay(struct net_bridge *br, unsigned long val)
666 unsigned long t = clock_t_to_jiffies(val);
669 spin_lock_bh(&br->lock);
670 if (br->stp_enabled != BR_NO_STP &&
671 (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
674 __br_set_forward_delay(br, t);
678 spin_unlock_bh(&br->lock);