1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Spanning tree protocol; generic parts
4 * Linux ethernet bridge
5 *
6 * Authors:
7 * Lennert Buytenhek <buytenh@gnu.org>
8 */
9 #include <linux/kernel.h>
10 #include <linux/rculist.h>
11 #include <net/switchdev.h>
12
13 #include "br_private.h"
14 #include "br_private_stp.h"
15
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.
18 */
19 #define MESSAGE_AGE_INCR ((HZ / 256) + 1)
20
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",
27 };
28
br_set_state(struct net_bridge_port * p,unsigned int state)29 void br_set_state(struct net_bridge_port *p, unsigned int state)
30 {
31 struct switchdev_attr attr = {
32 .orig_dev = p->dev,
33 .id = SWITCHDEV_ATTR_ID_PORT_STP_STATE,
34 .flags = SWITCHDEV_F_DEFER,
35 .u.stp_state = state,
36 };
37 int err;
38
39 p->state = state;
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);
44 else
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]);
48 }
49
50 /* called under bridge lock */
br_get_port(struct net_bridge * br,u16 port_no)51 struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no)
52 {
53 struct net_bridge_port *p;
54
55 list_for_each_entry_rcu(p, &br->port_list, list) {
56 if (p->port_no == port_no)
57 return p;
58 }
59
60 return NULL;
61 }
62
63 /* called under bridge lock */
br_should_become_root_port(const struct net_bridge_port * p,u16 root_port)64 static int br_should_become_root_port(const struct net_bridge_port *p,
65 u16 root_port)
66 {
67 struct net_bridge *br;
68 struct net_bridge_port *rp;
69 int t;
70
71 br = p->br;
72 if (p->state == BR_STATE_DISABLED ||
73 br_is_designated_port(p))
74 return 0;
75
76 if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0)
77 return 0;
78
79 if (!root_port)
80 return 1;
81
82 rp = br_get_port(br, root_port);
83
84 t = memcmp(&p->designated_root, &rp->designated_root, 8);
85 if (t < 0)
86 return 1;
87 else if (t > 0)
88 return 0;
89
90 if (p->designated_cost + p->path_cost <
91 rp->designated_cost + rp->path_cost)
92 return 1;
93 else if (p->designated_cost + p->path_cost >
94 rp->designated_cost + rp->path_cost)
95 return 0;
96
97 t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8);
98 if (t < 0)
99 return 1;
100 else if (t > 0)
101 return 0;
102
103 if (p->designated_port < rp->designated_port)
104 return 1;
105 else if (p->designated_port > rp->designated_port)
106 return 0;
107
108 if (p->port_id < rp->port_id)
109 return 1;
110
111 return 0;
112 }
113
br_root_port_block(const struct net_bridge * br,struct net_bridge_port * p)114 static void br_root_port_block(const struct net_bridge *br,
115 struct net_bridge_port *p)
116 {
117
118 br_notice(br, "port %u(%s) tried to become root port (blocked)",
119 (unsigned int) p->port_no, p->dev->name);
120
121 br_set_state(p, BR_STATE_LISTENING);
122 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
123
124 if (br->forward_delay > 0)
125 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
126 }
127
128 /* called under bridge lock */
br_root_selection(struct net_bridge * br)129 static void br_root_selection(struct net_bridge *br)
130 {
131 struct net_bridge_port *p;
132 u16 root_port = 0;
133
134 list_for_each_entry(p, &br->port_list, list) {
135 if (!br_should_become_root_port(p, root_port))
136 continue;
137
138 if (p->flags & BR_ROOT_BLOCK)
139 br_root_port_block(br, p);
140 else
141 root_port = p->port_no;
142 }
143
144 br->root_port = root_port;
145
146 if (!root_port) {
147 br->designated_root = br->bridge_id;
148 br->root_path_cost = 0;
149 } else {
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;
153 }
154 }
155
156 /* called under bridge lock */
br_become_root_bridge(struct net_bridge * br)157 void br_become_root_bridge(struct net_bridge *br)
158 {
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);
164
165 if (br->dev->flags & IFF_UP) {
166 br_config_bpdu_generation(br);
167 mod_timer(&br->hello_timer, jiffies + br->hello_time);
168 }
169 }
170
171 /* called under bridge lock */
br_transmit_config(struct net_bridge_port * p)172 void br_transmit_config(struct net_bridge_port *p)
173 {
174 struct br_config_bpdu bpdu;
175 struct net_bridge *br;
176
177 if (timer_pending(&p->hold_timer)) {
178 p->config_pending = 1;
179 return;
180 }
181
182 br = p->br;
183
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;
192 else {
193 struct net_bridge_port *root
194 = br_get_port(br, br->root_port);
195 bpdu.message_age = (jiffies - root->designated_age)
196 + MESSAGE_AGE_INCR;
197 }
198 bpdu.max_age = br->max_age;
199 bpdu.hello_time = br->hello_time;
200 bpdu.forward_delay = br->forward_delay;
201
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));
209 }
210 }
211
212 /* called under bridge lock */
br_record_config_information(struct net_bridge_port * p,const struct br_config_bpdu * bpdu)213 static void br_record_config_information(struct net_bridge_port *p,
214 const struct br_config_bpdu *bpdu)
215 {
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;
221
222 mod_timer(&p->message_age_timer, jiffies
223 + (bpdu->max_age - bpdu->message_age));
224 }
225
226 /* called under bridge lock */
br_record_config_timeout_values(struct net_bridge * br,const struct br_config_bpdu * bpdu)227 static void br_record_config_timeout_values(struct net_bridge *br,
228 const struct br_config_bpdu *bpdu)
229 {
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);
234 }
235
236 /* called under bridge lock */
br_transmit_tcn(struct net_bridge * br)237 void br_transmit_tcn(struct net_bridge *br)
238 {
239 struct net_bridge_port *p;
240
241 p = br_get_port(br, br->root_port);
242 if (p)
243 br_send_tcn_bpdu(p);
244 else
245 br_notice(br, "root port %u not found for topology notice\n",
246 br->root_port);
247 }
248
249 /* called under bridge lock */
br_should_become_designated_port(const struct net_bridge_port * p)250 static int br_should_become_designated_port(const struct net_bridge_port *p)
251 {
252 struct net_bridge *br;
253 int t;
254
255 br = p->br;
256 if (br_is_designated_port(p))
257 return 1;
258
259 if (memcmp(&p->designated_root, &br->designated_root, 8))
260 return 1;
261
262 if (br->root_path_cost < p->designated_cost)
263 return 1;
264 else if (br->root_path_cost > p->designated_cost)
265 return 0;
266
267 t = memcmp(&br->bridge_id, &p->designated_bridge, 8);
268 if (t < 0)
269 return 1;
270 else if (t > 0)
271 return 0;
272
273 if (p->port_id < p->designated_port)
274 return 1;
275
276 return 0;
277 }
278
279 /* called under bridge lock */
br_designated_port_selection(struct net_bridge * br)280 static void br_designated_port_selection(struct net_bridge *br)
281 {
282 struct net_bridge_port *p;
283
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);
288
289 }
290 }
291
292 /* called under bridge lock */
br_supersedes_port_info(const struct net_bridge_port * p,const struct br_config_bpdu * bpdu)293 static int br_supersedes_port_info(const struct net_bridge_port *p,
294 const struct br_config_bpdu *bpdu)
295 {
296 int t;
297
298 t = memcmp(&bpdu->root, &p->designated_root, 8);
299 if (t < 0)
300 return 1;
301 else if (t > 0)
302 return 0;
303
304 if (bpdu->root_path_cost < p->designated_cost)
305 return 1;
306 else if (bpdu->root_path_cost > p->designated_cost)
307 return 0;
308
309 t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8);
310 if (t < 0)
311 return 1;
312 else if (t > 0)
313 return 0;
314
315 if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8))
316 return 1;
317
318 if (bpdu->port_id <= p->designated_port)
319 return 1;
320
321 return 0;
322 }
323
324 /* called under bridge lock */
br_topology_change_acknowledged(struct net_bridge * br)325 static void br_topology_change_acknowledged(struct net_bridge *br)
326 {
327 br->topology_change_detected = 0;
328 del_timer(&br->tcn_timer);
329 }
330
331 /* called under bridge lock */
br_topology_change_detection(struct net_bridge * br)332 void br_topology_change_detection(struct net_bridge *br)
333 {
334 int isroot = br_is_root_bridge(br);
335
336 if (br->stp_enabled != BR_KERNEL_STP)
337 return;
338
339 br_info(br, "topology change detected, %s\n",
340 isroot ? "propagating" : "sending tcn bpdu");
341
342 if (isroot) {
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) {
347 br_transmit_tcn(br);
348 mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time);
349 }
350
351 br->topology_change_detected = 1;
352 }
353
354 /* called under bridge lock */
br_config_bpdu_generation(struct net_bridge * br)355 void br_config_bpdu_generation(struct net_bridge *br)
356 {
357 struct net_bridge_port *p;
358
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);
363 }
364 }
365
366 /* called under bridge lock */
br_reply(struct net_bridge_port * p)367 static void br_reply(struct net_bridge_port *p)
368 {
369 br_transmit_config(p);
370 }
371
372 /* called under bridge lock */
br_configuration_update(struct net_bridge * br)373 void br_configuration_update(struct net_bridge *br)
374 {
375 br_root_selection(br);
376 br_designated_port_selection(br);
377 }
378
379 /* called under bridge lock */
br_become_designated_port(struct net_bridge_port * p)380 void br_become_designated_port(struct net_bridge_port *p)
381 {
382 struct net_bridge *br;
383
384 br = p->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;
389 }
390
391
392 /* called under bridge lock */
br_make_blocking(struct net_bridge_port * p)393 static void br_make_blocking(struct net_bridge_port *p)
394 {
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);
400
401 br_set_state(p, BR_STATE_BLOCKING);
402 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
403
404 del_timer(&p->forward_delay_timer);
405 }
406 }
407
408 /* called under bridge lock */
br_make_forwarding(struct net_bridge_port * p)409 static void br_make_forwarding(struct net_bridge_port *p)
410 {
411 struct net_bridge *br = p->br;
412
413 if (p->state != BR_STATE_BLOCKING)
414 return;
415
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);
422 else
423 br_set_state(p, BR_STATE_LEARNING);
424
425 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
426
427 if (br->forward_delay != 0)
428 mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay);
429 }
430
431 /* called under bridge lock */
br_port_state_selection(struct net_bridge * br)432 void br_port_state_selection(struct net_bridge *br)
433 {
434 struct net_bridge_port *p;
435 unsigned int liveports = 0;
436
437 list_for_each_entry(p, &br->port_list, list) {
438 if (p->state == BR_STATE_DISABLED)
439 continue;
440
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);
450 } else {
451 p->config_pending = 0;
452 p->topology_change_ack = 0;
453 br_make_blocking(p);
454 }
455 }
456
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.
462 */
463 if (p->state == BR_STATE_FORWARDING)
464 ++liveports;
465 }
466
467 if (liveports == 0)
468 netif_carrier_off(br->dev);
469 else
470 netif_carrier_on(br->dev);
471 }
472
473 /* called under bridge lock */
br_topology_change_acknowledge(struct net_bridge_port * p)474 static void br_topology_change_acknowledge(struct net_bridge_port *p)
475 {
476 p->topology_change_ack = 1;
477 br_transmit_config(p);
478 }
479
480 /* called under bridge lock */
br_received_config_bpdu(struct net_bridge_port * p,const struct br_config_bpdu * bpdu)481 void br_received_config_bpdu(struct net_bridge_port *p,
482 const struct br_config_bpdu *bpdu)
483 {
484 struct net_bridge *br;
485 int was_root;
486
487 br = p->br;
488 was_root = br_is_root_bridge(br);
489
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);
494
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);
499 br_transmit_tcn(br);
500
501 mod_timer(&br->tcn_timer,
502 jiffies + br->bridge_hello_time);
503 }
504 }
505
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);
511 }
512 } else if (br_is_designated_port(p)) {
513 br_reply(p);
514 }
515 }
516
517 /* called under bridge lock */
br_received_tcn_bpdu(struct net_bridge_port * p)518 void br_received_tcn_bpdu(struct net_bridge_port *p)
519 {
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);
523
524 br_topology_change_detection(p->br);
525 br_topology_change_acknowledge(p);
526 }
527 }
528
529 /* Change bridge STP parameter */
br_set_hello_time(struct net_bridge * br,unsigned long val)530 int br_set_hello_time(struct net_bridge *br, unsigned long val)
531 {
532 unsigned long t = clock_t_to_jiffies(val);
533
534 if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME)
535 return -ERANGE;
536
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);
542 return 0;
543 }
544
br_set_max_age(struct net_bridge * br,unsigned long val)545 int br_set_max_age(struct net_bridge *br, unsigned long val)
546 {
547 unsigned long t = clock_t_to_jiffies(val);
548
549 if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE)
550 return -ERANGE;
551
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);
557 return 0;
558
559 }
560
561 /* called under bridge lock */
__set_ageing_time(struct net_device * dev,unsigned long t)562 int __set_ageing_time(struct net_device *dev, unsigned long t)
563 {
564 struct switchdev_attr attr = {
565 .orig_dev = dev,
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),
569 };
570 int err;
571
572 err = switchdev_port_attr_set(dev, &attr);
573 if (err && err != -EOPNOTSUPP)
574 return err;
575
576 return 0;
577 }
578
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)
584 *
585 * Offloaded switch entries maybe more restrictive
586 */
br_set_ageing_time(struct net_bridge * br,clock_t ageing_time)587 int br_set_ageing_time(struct net_bridge *br, clock_t ageing_time)
588 {
589 unsigned long t = clock_t_to_jiffies(ageing_time);
590 int err;
591
592 err = __set_ageing_time(br->dev, t);
593 if (err)
594 return err;
595
596 spin_lock_bh(&br->lock);
597 br->bridge_ageing_time = t;
598 br->ageing_time = t;
599 spin_unlock_bh(&br->lock);
600
601 mod_delayed_work(system_long_wq, &br->gc_work, 0);
602
603 return 0;
604 }
605
606 /* called under bridge lock */
__br_set_topology_change(struct net_bridge * br,unsigned char val)607 void __br_set_topology_change(struct net_bridge *br, unsigned char val)
608 {
609 unsigned long t;
610 int err;
611
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.
615 */
616
617 if (val) {
618 t = 2 * br->forward_delay;
619 br_debug(br, "decreasing ageing time to %lu\n", t);
620 } else {
621 t = br->bridge_ageing_time;
622 br_debug(br, "restoring ageing time to %lu\n", t);
623 }
624
625 err = __set_ageing_time(br->dev, t);
626 if (err)
627 br_warn(br, "error offloading ageing time\n");
628 else
629 br->ageing_time = t;
630 }
631
632 br->topology_change = val;
633 }
634
__br_set_forward_delay(struct net_bridge * br,unsigned long t)635 void __br_set_forward_delay(struct net_bridge *br, unsigned long t)
636 {
637 br->bridge_forward_delay = t;
638 if (br_is_root_bridge(br))
639 br->forward_delay = br->bridge_forward_delay;
640 }
641
br_set_forward_delay(struct net_bridge * br,unsigned long val)642 int br_set_forward_delay(struct net_bridge *br, unsigned long val)
643 {
644 unsigned long t = clock_t_to_jiffies(val);
645 int err = -ERANGE;
646
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))
650 goto unlock;
651
652 __br_set_forward_delay(br, t);
653 err = 0;
654
655 unlock:
656 spin_unlock_bh(&br->lock);
657 return err;
658 }
659