1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Spanning tree protocol; interface code
4 * Linux ethernet bridge
5 *
6 * Authors:
7 * Lennert Buytenhek <buytenh@gnu.org>
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/kmod.h>
12 #include <linux/etherdevice.h>
13 #include <linux/rtnetlink.h>
14 #include <net/switchdev.h>
15
16 #include "br_private.h"
17 #include "br_private_stp.h"
18
19
20 /* Port id is composed of priority and port number.
21 * NB: some bits of priority are dropped to
22 * make room for more ports.
23 */
24 static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
25 {
26 return ((u16)priority << BR_PORT_BITS)
27 | (port_no & ((1<<BR_PORT_BITS)-1));
28 }
29
30 #define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)
31
32 /* called under bridge lock */
33 void br_init_port(struct net_bridge_port *p)
34 {
35 int err;
36
37 p->port_id = br_make_port_id(p->priority, p->port_no);
38 br_become_designated_port(p);
39 br_set_state(p, BR_STATE_BLOCKING);
40 p->topology_change_ack = 0;
41 p->config_pending = 0;
42
43 err = __set_ageing_time(p->dev, p->br->ageing_time);
44 if (err)
45 netdev_err(p->dev, "failed to offload ageing time\n");
46 }
47
48 /* NO locks held */
49 void br_stp_enable_bridge(struct net_bridge *br)
50 {
51 struct net_bridge_port *p;
52
53 spin_lock_bh(&br->lock);
54 if (br->stp_enabled == BR_KERNEL_STP)
55 mod_timer(&br->hello_timer, jiffies + br->hello_time);
56 mod_delayed_work(system_long_wq, &br->gc_work, HZ / 10);
57
58 br_config_bpdu_generation(br);
59
60 list_for_each_entry(p, &br->port_list, list) {
61 if (netif_running(p->dev) && netif_oper_up(p->dev))
62 br_stp_enable_port(p);
63
64 }
65 spin_unlock_bh(&br->lock);
66 }
67
68 /* NO locks held */
69 void br_stp_disable_bridge(struct net_bridge *br)
70 {
71 struct net_bridge_port *p;
72
73 spin_lock_bh(&br->lock);
74 list_for_each_entry(p, &br->port_list, list) {
75 if (p->state != BR_STATE_DISABLED)
76 br_stp_disable_port(p);
77
78 }
79
80 __br_set_topology_change(br, 0);
81 br->topology_change_detected = 0;
82 spin_unlock_bh(&br->lock);
83
84 del_timer_sync(&br->hello_timer);
85 del_timer_sync(&br->topology_change_timer);
86 del_timer_sync(&br->tcn_timer);
87 cancel_delayed_work_sync(&br->gc_work);
88 }
89
90 /* called under bridge lock */
91 void br_stp_enable_port(struct net_bridge_port *p)
92 {
93 br_init_port(p);
94 br_port_state_selection(p->br);
95 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
96 }
97
98 /* called under bridge lock */
99 void br_stp_disable_port(struct net_bridge_port *p)
100 {
101 struct net_bridge *br = p->br;
102 int wasroot;
103
104 wasroot = br_is_root_bridge(br);
105 br_become_designated_port(p);
106 br_set_state(p, BR_STATE_DISABLED);
107 p->topology_change_ack = 0;
108 p->config_pending = 0;
109
110 br_ifinfo_notify(RTM_NEWLINK, NULL, p);
111
112 del_timer(&p->message_age_timer);
113 del_timer(&p->forward_delay_timer);
114 del_timer(&p->hold_timer);
115
116 if (!rcu_access_pointer(p->backup_port))
117 br_fdb_delete_by_port(br, p, 0, 0);
118 br_multicast_disable_port(p);
119
120 br_configuration_update(br);
121
122 br_port_state_selection(br);
123
124 if (br_is_root_bridge(br) && !wasroot)
125 br_become_root_bridge(br);
126 }
127
128 static int br_stp_call_user(struct net_bridge *br, char *arg)
129 {
130 char *argv[] = { BR_STP_PROG, br->dev->name, arg, NULL };
131 char *envp[] = { NULL };
132 int rc;
133
134 /* call userspace STP and report program errors */
135 rc = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
136 if (rc > 0) {
137 if (rc & 0xff)
138 br_debug(br, BR_STP_PROG " received signal %d\n",
139 rc & 0x7f);
140 else
141 br_debug(br, BR_STP_PROG " exited with code %d\n",
142 (rc >> 8) & 0xff);
143 }
144
145 return rc;
146 }
147
148 static void br_stp_start(struct net_bridge *br)
149 {
150 int err = -ENOENT;
151
152 if (net_eq(dev_net(br->dev), &init_net))
153 err = br_stp_call_user(br, "start");
154
155 if (err && err != -ENOENT)
156 br_err(br, "failed to start userspace STP (%d)\n", err);
157
158 spin_lock_bh(&br->lock);
159
160 if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)
161 __br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);
162 else if (br->bridge_forward_delay > BR_MAX_FORWARD_DELAY)
163 __br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);
164
165 if (!err) {
166 br->stp_enabled = BR_USER_STP;
167 br_debug(br, "userspace STP started\n");
168 } else {
169 br->stp_enabled = BR_KERNEL_STP;
170 br_debug(br, "using kernel STP\n");
171
172 /* To start timers on any ports left in blocking */
173 if (br->dev->flags & IFF_UP)
174 mod_timer(&br->hello_timer, jiffies + br->hello_time);
175 br_port_state_selection(br);
176 }
177
178 spin_unlock_bh(&br->lock);
179 }
180
181 static void br_stp_stop(struct net_bridge *br)
182 {
183 int err;
184
185 if (br->stp_enabled == BR_USER_STP) {
186 err = br_stp_call_user(br, "stop");
187 if (err)
188 br_err(br, "failed to stop userspace STP (%d)\n", err);
189
190 /* To start timers on any ports left in blocking */
191 spin_lock_bh(&br->lock);
192 br_port_state_selection(br);
193 spin_unlock_bh(&br->lock);
194 }
195
196 br->stp_enabled = BR_NO_STP;
197 }
198
199 int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
200 struct netlink_ext_ack *extack)
201 {
202 ASSERT_RTNL();
203
204 if (br_mrp_enabled(br)) {
205 NL_SET_ERR_MSG_MOD(extack,
206 "STP can't be enabled if MRP is already enabled");
207 return -EINVAL;
208 }
209
210 if (val) {
211 if (br->stp_enabled == BR_NO_STP)
212 br_stp_start(br);
213 } else {
214 if (br->stp_enabled != BR_NO_STP)
215 br_stp_stop(br);
216 }
217
218 return 0;
219 }
220
221 /* called under bridge lock */
222 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
223 {
224 /* should be aligned on 2 bytes for ether_addr_equal() */
225 unsigned short oldaddr_aligned[ETH_ALEN >> 1];
226 unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
227 struct net_bridge_port *p;
228 int wasroot;
229
230 wasroot = br_is_root_bridge(br);
231
232 br_fdb_change_mac_address(br, addr);
233
234 memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
235 memcpy(br->bridge_id.addr, addr, ETH_ALEN);
236 eth_hw_addr_set(br->dev, addr);
237
238 list_for_each_entry(p, &br->port_list, list) {
239 if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
240 memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
241
242 if (ether_addr_equal(p->designated_root.addr, oldaddr))
243 memcpy(p->designated_root.addr, addr, ETH_ALEN);
244 }
245
246 br_configuration_update(br);
247 br_port_state_selection(br);
248 if (br_is_root_bridge(br) && !wasroot)
249 br_become_root_bridge(br);
250 }
251
252 /* should be aligned on 2 bytes for ether_addr_equal() */
253 static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
254
255 /* called under bridge lock */
256 bool br_stp_recalculate_bridge_id(struct net_bridge *br)
257 {
258 const unsigned char *br_mac_zero =
259 (const unsigned char *)br_mac_zero_aligned;
260 const unsigned char *addr = br_mac_zero;
261 struct net_bridge_port *p;
262
263 /* user has chosen a value so keep it */
264 if (br->dev->addr_assign_type == NET_ADDR_SET)
265 return false;
266
267 list_for_each_entry(p, &br->port_list, list) {
268 if (addr == br_mac_zero ||
269 memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
270 addr = p->dev->dev_addr;
271
272 }
273
274 if (ether_addr_equal(br->bridge_id.addr, addr))
275 return false; /* no change */
276
277 br_stp_change_bridge_id(br, addr);
278 return true;
279 }
280
281 /* Acquires and releases bridge lock */
282 void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
283 {
284 struct net_bridge_port *p;
285 int wasroot;
286
287 spin_lock_bh(&br->lock);
288 wasroot = br_is_root_bridge(br);
289
290 list_for_each_entry(p, &br->port_list, list) {
291 if (p->state != BR_STATE_DISABLED &&
292 br_is_designated_port(p)) {
293 p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
294 p->designated_bridge.prio[1] = newprio & 0xFF;
295 }
296
297 }
298
299 br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
300 br->bridge_id.prio[1] = newprio & 0xFF;
301 br_configuration_update(br);
302 br_port_state_selection(br);
303 if (br_is_root_bridge(br) && !wasroot)
304 br_become_root_bridge(br);
305 spin_unlock_bh(&br->lock);
306 }
307
308 /* called under bridge lock */
309 int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
310 {
311 port_id new_port_id;
312
313 if (newprio > BR_MAX_PORT_PRIORITY)
314 return -ERANGE;
315
316 new_port_id = br_make_port_id(newprio, p->port_no);
317 if (br_is_designated_port(p))
318 p->designated_port = new_port_id;
319
320 p->port_id = new_port_id;
321 p->priority = newprio;
322 if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
323 p->port_id < p->designated_port) {
324 br_become_designated_port(p);
325 br_port_state_selection(p->br);
326 }
327
328 return 0;
329 }
330
331 /* called under bridge lock */
332 int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
333 {
334 if (path_cost < BR_MIN_PATH_COST ||
335 path_cost > BR_MAX_PATH_COST)
336 return -ERANGE;
337
338 p->flags |= BR_ADMIN_COST;
339 p->path_cost = path_cost;
340 br_configuration_update(p->br);
341 br_port_state_selection(p->br);
342 return 0;
343 }
344
345 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
346 {
347 return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
348 id->prio[0], id->prio[1],
349 id->addr[0], id->addr[1], id->addr[2],
350 id->addr[3], id->addr[4], id->addr[5]);
351 }
352
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