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
);