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]);
49 if (p->br->stp_enabled == BR_KERNEL_STP) {
51 case BR_STATE_BLOCKING:
52 p->stp_xstats.transition_blk++;
54 case BR_STATE_FORWARDING:
55 p->stp_xstats.transition_fwd++;
61 /* called under bridge lock */
62 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
64 struct net_bridge_port *p;
66 list_for_each_entry_rcu(p, &br->port_list, list) {
67 if (p->port_no == port_no)
74 /* called under bridge lock */
75 static int br_should_become_root_port(const struct net_bridge_port *p,
78 struct net_bridge *br;
79 struct net_bridge_port *rp;
83 if (p->state == BR_STATE_DISABLED ||
84 br_is_designated_port(p))
87 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
93 rp = br_get_port(br, root_port);
95 t = memcmp(&p->designated_root, &rp->designated_root, 8);
101 if (p->designated_cost + p->path_cost <
102 rp->designated_cost + rp->path_cost)
104 else if (p->designated_cost + p->path_cost >
105 rp->designated_cost + rp->path_cost)
108 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
114 if (p->designated_port < rp->designated_port)
116 else if (p->designated_port > rp->designated_port)
119 if (p->port_id < rp->port_id)
125 static void br_root_port_block(const struct net_bridge *br,
126 struct net_bridge_port *p)
129 br_notice(br, "port %u(%s) tried to become root port (blocked)",
130 (unsigned int) p->port_no, p->dev->name);
132 br_set_state(p, BR_STATE_LISTENING);
133 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
135 if (br->forward_delay > 0)
136 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
139 /* called under bridge lock */
140 static void br_root_selection(struct net_bridge *br)
142 struct net_bridge_port *p;
145 list_for_each_entry(p, &br->port_list, list) {
146 if (!br_should_become_root_port(p, root_port))
149 if (p->flags & BR_ROOT_BLOCK)
150 br_root_port_block(br, p);
152 root_port = p->port_no;
155 br->root_port = root_port;
158 br->designated_root = br->bridge_id;
159 br->root_path_cost = 0;
161 p = br_get_port(br, root_port);
162 br->designated_root = p->designated_root;
163 br->root_path_cost = p->designated_cost + p->path_cost;
167 /* called under bridge lock */
168 void br_become_root_bridge(struct net_bridge *br)
170 br->max_age = br->bridge_max_age;
171 br->hello_time = br->bridge_hello_time;
172 br->forward_delay = br->bridge_forward_delay;
173 br_topology_change_detection(br);
174 del_timer(&br->tcn_timer);
176 if (br->dev->flags & IFF_UP) {
177 br_config_bpdu_generation(br);
178 mod_timer(&br->hello_timer, jiffies + br->hello_time);
182 /* called under bridge lock */
183 void br_transmit_config(struct net_bridge_port *p)
185 struct br_config_bpdu bpdu;
186 struct net_bridge *br;
188 if (timer_pending(&p->hold_timer)) {
189 p->config_pending = 1;
195 bpdu.topology_change = br->topology_change;
196 bpdu.topology_change_ack = p->topology_change_ack;
197 bpdu.root = br->designated_root;
198 bpdu.root_path_cost = br->root_path_cost;
199 bpdu.bridge_id = br->bridge_id;
200 bpdu.port_id = p->port_id;
201 if (br_is_root_bridge(br))
202 bpdu.message_age = 0;
204 struct net_bridge_port *root
205 = br_get_port(br, br->root_port);
206 bpdu.message_age = (jiffies - root->designated_age)
209 bpdu.max_age = br->max_age;
210 bpdu.hello_time = br->hello_time;
211 bpdu.forward_delay = br->forward_delay;
213 if (bpdu.message_age < br->max_age) {
214 br_send_config_bpdu(p, &bpdu);
215 p->topology_change_ack = 0;
216 p->config_pending = 0;
217 if (p->br->stp_enabled == BR_KERNEL_STP)
218 mod_timer(&p->hold_timer,
219 round_jiffies(jiffies + BR_HOLD_TIME));
223 /* called under bridge lock */
224 static void br_record_config_information(struct net_bridge_port *p,
225 const struct br_config_bpdu *bpdu)
227 p->designated_root = bpdu->root;
228 p->designated_cost = bpdu->root_path_cost;
229 p->designated_bridge = bpdu->bridge_id;
230 p->designated_port = bpdu->port_id;
231 p->designated_age = jiffies - bpdu->message_age;
233 mod_timer(&p->message_age_timer, jiffies
234 + (bpdu->max_age - bpdu->message_age));
237 /* called under bridge lock */
238 static void br_record_config_timeout_values(struct net_bridge *br,
239 const struct br_config_bpdu *bpdu)
241 br->max_age = bpdu->max_age;
242 br->hello_time = bpdu->hello_time;
243 br->forward_delay = bpdu->forward_delay;
244 __br_set_topology_change(br, bpdu->topology_change);
247 /* called under bridge lock */
248 void br_transmit_tcn(struct net_bridge *br)
250 struct net_bridge_port *p;
252 p = br_get_port(br, br->root_port);
256 br_notice(br, "root port %u not found for topology notice\n",
260 /* called under bridge lock */
261 static int br_should_become_designated_port(const struct net_bridge_port *p)
263 struct net_bridge *br;
267 if (br_is_designated_port(p))
270 if (memcmp(&p->designated_root, &br->designated_root, 8))
273 if (br->root_path_cost < p->designated_cost)
275 else if (br->root_path_cost > p->designated_cost)
278 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
284 if (p->port_id < p->designated_port)
290 /* called under bridge lock */
291 static void br_designated_port_selection(struct net_bridge *br)
293 struct net_bridge_port *p;
295 list_for_each_entry(p, &br->port_list, list) {
296 if (p->state != BR_STATE_DISABLED &&
297 br_should_become_designated_port(p))
298 br_become_designated_port(p);
303 /* called under bridge lock */
304 static int br_supersedes_port_info(const struct net_bridge_port *p,
305 const struct br_config_bpdu *bpdu)
309 t = memcmp(&bpdu->root, &p->designated_root, 8);
315 if (bpdu->root_path_cost < p->designated_cost)
317 else if (bpdu->root_path_cost > p->designated_cost)
320 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
326 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
329 if (bpdu->port_id <= p->designated_port)
335 /* called under bridge lock */
336 static void br_topology_change_acknowledged(struct net_bridge *br)
338 br->topology_change_detected = 0;
339 del_timer(&br->tcn_timer);
342 /* called under bridge lock */
343 void br_topology_change_detection(struct net_bridge *br)
345 int isroot = br_is_root_bridge(br);
347 if (br->stp_enabled != BR_KERNEL_STP)
350 br_info(br, "topology change detected, %s\n",
351 isroot ? "propagating" : "sending tcn bpdu");
354 __br_set_topology_change(br, 1);
355 mod_timer(&br->topology_change_timer, jiffies
356 + br->bridge_forward_delay + br->bridge_max_age);
357 } else if (!br->topology_change_detected) {
359 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
362 br->topology_change_detected = 1;
365 /* called under bridge lock */
366 void br_config_bpdu_generation(struct net_bridge *br)
368 struct net_bridge_port *p;
370 list_for_each_entry(p, &br->port_list, list) {
371 if (p->state != BR_STATE_DISABLED &&
372 br_is_designated_port(p))
373 br_transmit_config(p);
377 /* called under bridge lock */
378 static void br_reply(struct net_bridge_port *p)
380 br_transmit_config(p);
383 /* called under bridge lock */
384 void br_configuration_update(struct net_bridge *br)
386 br_root_selection(br);
387 br_designated_port_selection(br);
390 /* called under bridge lock */
391 void br_become_designated_port(struct net_bridge_port *p)
393 struct net_bridge *br;
396 p->designated_root = br->designated_root;
397 p->designated_cost = br->root_path_cost;
398 p->designated_bridge = br->bridge_id;
399 p->designated_port = p->port_id;
403 /* called under bridge lock */
404 static void br_make_blocking(struct net_bridge_port *p)
406 if (p->state != BR_STATE_DISABLED &&
407 p->state != BR_STATE_BLOCKING) {
408 if (p->state == BR_STATE_FORWARDING ||
409 p->state == BR_STATE_LEARNING)
410 br_topology_change_detection(p->br);
412 br_set_state(p, BR_STATE_BLOCKING);
413 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
415 del_timer(&p->forward_delay_timer);
419 /* called under bridge lock */
420 static void br_make_forwarding(struct net_bridge_port *p)
422 struct net_bridge *br = p->br;
424 if (p->state != BR_STATE_BLOCKING)
427 if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) {
428 br_set_state(p, BR_STATE_FORWARDING);
429 br_topology_change_detection(br);
430 del_timer(&p->forward_delay_timer);
431 } else if (br->stp_enabled == BR_KERNEL_STP)
432 br_set_state(p, BR_STATE_LISTENING);
434 br_set_state(p, BR_STATE_LEARNING);
436 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
438 if (br->forward_delay != 0)
439 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
442 /* called under bridge lock */
443 void br_port_state_selection(struct net_bridge *br)
445 struct net_bridge_port *p;
446 unsigned int liveports = 0;
448 list_for_each_entry(p, &br->port_list, list) {
449 if (p->state == BR_STATE_DISABLED)
452 /* Don't change port states if userspace is handling STP */
453 if (br->stp_enabled != BR_USER_STP) {
454 if (p->port_no == br->root_port) {
455 p->config_pending = 0;
456 p->topology_change_ack = 0;
457 br_make_forwarding(p);
458 } else if (br_is_designated_port(p)) {
459 del_timer(&p->message_age_timer);
460 br_make_forwarding(p);
462 p->config_pending = 0;
463 p->topology_change_ack = 0;
468 if (p->state != BR_STATE_BLOCKING)
469 br_multicast_enable_port(p);
470 /* Multicast is not disabled for the port when it goes in
471 * blocking state because the timers will expire and stop by
472 * themselves without sending more queries.
474 if (p->state == BR_STATE_FORWARDING)
479 netif_carrier_off(br->dev);
481 netif_carrier_on(br->dev);
484 /* called under bridge lock */
485 static void br_topology_change_acknowledge(struct net_bridge_port *p)
487 p->topology_change_ack = 1;
488 br_transmit_config(p);
491 /* called under bridge lock */
492 void br_received_config_bpdu(struct net_bridge_port *p,
493 const struct br_config_bpdu *bpdu)
495 struct net_bridge *br;
498 p->stp_xstats.rx_bpdu++;
501 was_root = br_is_root_bridge(br);
503 if (br_supersedes_port_info(p, bpdu)) {
504 br_record_config_information(p, bpdu);
505 br_configuration_update(br);
506 br_port_state_selection(br);
508 if (!br_is_root_bridge(br) && was_root) {
509 del_timer(&br->hello_timer);
510 if (br->topology_change_detected) {
511 del_timer(&br->topology_change_timer);
514 mod_timer(&br->tcn_timer,
515 jiffies + br->bridge_hello_time);
519 if (p->port_no == br->root_port) {
520 br_record_config_timeout_values(br, bpdu);
521 br_config_bpdu_generation(br);
522 if (bpdu->topology_change_ack)
523 br_topology_change_acknowledged(br);
525 } else if (br_is_designated_port(p)) {
530 /* called under bridge lock */
531 void br_received_tcn_bpdu(struct net_bridge_port *p)
533 p->stp_xstats.rx_tcn++;
535 if (br_is_designated_port(p)) {
536 br_info(p->br, "port %u(%s) received tcn bpdu\n",
537 (unsigned int) p->port_no, p->dev->name);
539 br_topology_change_detection(p->br);
540 br_topology_change_acknowledge(p);
544 /* Change bridge STP parameter */
545 int br_set_hello_time(struct net_bridge *br, unsigned long val)
547 unsigned long t = clock_t_to_jiffies(val);
549 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
552 spin_lock_bh(&br->lock);
553 br->bridge_hello_time = t;
554 if (br_is_root_bridge(br))
555 br->hello_time = br->bridge_hello_time;
556 spin_unlock_bh(&br->lock);
560 int br_set_max_age(struct net_bridge *br, unsigned long val)
562 unsigned long t = clock_t_to_jiffies(val);
564 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
567 spin_lock_bh(&br->lock);
568 br->bridge_max_age = t;
569 if (br_is_root_bridge(br))
570 br->max_age = br->bridge_max_age;
571 spin_unlock_bh(&br->lock);
576 /* called under bridge lock */
577 int __set_ageing_time(struct net_device *dev, unsigned long t)
579 struct switchdev_attr attr = {
581 .id = SWITCHDEV_ATTR_ID_BRIDGE_AGEING_TIME,
582 .flags = SWITCHDEV_F_SKIP_EOPNOTSUPP | SWITCHDEV_F_DEFER,
583 .u.ageing_time = jiffies_to_clock_t(t),
587 err = switchdev_port_attr_set(dev, &attr);
588 if (err && err != -EOPNOTSUPP)
594 /* Set time interval that dynamic forwarding entries live
595 * For pure software bridge, allow values outside the 802.1
596 * standard specification for special cases:
597 * 0 - entry never ages (all permanant)
598 * 1 - entry disappears (no persistance)
600 * Offloaded switch entries maybe more restrictive
602 int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time)
604 unsigned long t = clock_t_to_jiffies(ageing_time);
607 err = __set_ageing_time(br->dev, t);
611 spin_lock_bh(&br->lock);
612 br->bridge_ageing_time = t;
614 spin_unlock_bh(&br->lock);
616 mod_delayed_work(system_long_wq, &br->gc_work, 0);
621 /* called under bridge lock */
622 void __br_set_topology_change(struct net_bridge *br, unsigned char val)
627 if (br->stp_enabled == BR_KERNEL_STP && br->topology_change != val) {
628 /* On topology change, set the bridge ageing time to twice the
629 * forward delay. Otherwise, restore its default ageing time.
633 t = 2 * br->forward_delay;
634 br_debug(br, "decreasing ageing time to %lu\n", t);
636 t = br->bridge_ageing_time;
637 br_debug(br, "restoring ageing time to %lu\n", t);
640 err = __set_ageing_time(br->dev, t);
642 br_warn(br, "error offloading ageing time\n");
647 br->topology_change = val;
650 void __br_set_forward_delay(struct net_bridge *br, unsigned long t)
652 br->bridge_forward_delay = t;
653 if (br_is_root_bridge(br))
654 br->forward_delay = br->bridge_forward_delay;
657 int br_set_forward_delay(struct net_bridge *br, unsigned long val)
659 unsigned long t = clock_t_to_jiffies(val);
662 spin_lock_bh(&br->lock);
663 if (br->stp_enabled != BR_NO_STP &&
664 (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
667 __br_set_forward_delay(br, t);
671 spin_unlock_bh(&br->lock);