1 /*
2 * Spanning tree protocol; interface code
3 * Linux ethernet bridge
4 *
5 * Authors:
6 * Lennert Buytenhek <buytenh@gnu.org>
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 */
13
14 #include <linux/kernel.h>
15 #include <linux/kmod.h>
16 #include <linux/etherdevice.h>
17 #include <linux/rtnetlink.h>
18
19 #include "br_private.h"
20 #include "br_private_stp.h"
21
22
23 /* Port id is composed of priority and port number.
24 * NB: some bits of priority are dropped to
25 * make room for more ports.
26 */
br_make_port_id(__u8 priority,__u16 port_no)27 static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
28 {
29 return ((u16)priority << BR_PORT_BITS)
30 | (port_no & ((1<<BR_PORT_BITS)-1));
31 }
32
33 #define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)
34
35 /* called under bridge lock */
br_init_port(struct net_bridge_port * p)36 void br_init_port(struct net_bridge_port *p)
37 {
38 p->port_id = br_make_port_id(p->priority, p->port_no);
39 br_become_designated_port(p);
40 br_set_state(p, BR_STATE_BLOCKING);
41 p->topology_change_ack = 0;
42 p->config_pending = 0;
43 }
44
45 /* called under bridge lock */
br_stp_enable_bridge(struct net_bridge * br)46 void br_stp_enable_bridge(struct net_bridge *br)
47 {
48 struct net_bridge_port *p;
49
50 spin_lock_bh(&br->lock);
51 mod_timer(&br->hello_timer, jiffies + br->hello_time);
52 mod_timer(&br->gc_timer, jiffies + HZ/10);
53
54 br_config_bpdu_generation(br);
55
56 list_for_each_entry(p, &br->port_list, list) {
57 if (netif_running(p->dev) && netif_oper_up(p->dev))
58 br_stp_enable_port(p);
59
60 }
61 spin_unlock_bh(&br->lock);
62 }
63
64 /* NO locks held */
br_stp_disable_bridge(struct net_bridge * br)65 void br_stp_disable_bridge(struct net_bridge *br)
66 {
67 struct net_bridge_port *p;
68
69 spin_lock_bh(&br->lock);
70 list_for_each_entry(p, &br->port_list, list) {
71 if (p->state != BR_STATE_DISABLED)
72 br_stp_disable_port(p);
73
74 }
75
76 br->topology_change = 0;
77 br->topology_change_detected = 0;
78 spin_unlock_bh(&br->lock);
79
80 del_timer_sync(&br->hello_timer);
81 del_timer_sync(&br->topology_change_timer);
82 del_timer_sync(&br->tcn_timer);
83 del_timer_sync(&br->gc_timer);
84 }
85
86 /* called under bridge lock */
br_stp_enable_port(struct net_bridge_port * p)87 void br_stp_enable_port(struct net_bridge_port *p)
88 {
89 br_init_port(p);
90 br_port_state_selection(p->br);
91 br_log_state(p);
92 br_ifinfo_notify(RTM_NEWLINK, p);
93 }
94
95 /* called under bridge lock */
br_stp_disable_port(struct net_bridge_port * p)96 void br_stp_disable_port(struct net_bridge_port *p)
97 {
98 struct net_bridge *br = p->br;
99 int wasroot;
100
101 wasroot = br_is_root_bridge(br);
102 br_become_designated_port(p);
103 br_set_state(p, BR_STATE_DISABLED);
104 p->topology_change_ack = 0;
105 p->config_pending = 0;
106
107 br_log_state(p);
108 br_ifinfo_notify(RTM_NEWLINK, p);
109
110 del_timer(&p->message_age_timer);
111 del_timer(&p->forward_delay_timer);
112 del_timer(&p->hold_timer);
113
114 br_fdb_delete_by_port(br, p, 0);
115 br_multicast_disable_port(p);
116
117 br_configuration_update(br);
118
119 br_port_state_selection(br);
120
121 if (br_is_root_bridge(br) && !wasroot)
122 br_become_root_bridge(br);
123 }
124
br_stp_start(struct net_bridge * br)125 static void br_stp_start(struct net_bridge *br)
126 {
127 int r;
128 char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL };
129 char *envp[] = { NULL };
130
131 if (net_eq(dev_net(br->dev), &init_net))
132 r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
133 else
134 r = -ENOENT;
135
136 spin_lock_bh(&br->lock);
137
138 if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)
139 __br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);
140 else if (br->bridge_forward_delay > BR_MAX_FORWARD_DELAY)
141 __br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);
142
143 if (r == 0) {
144 br->stp_enabled = BR_USER_STP;
145 br_debug(br, "userspace STP started\n");
146 } else {
147 br->stp_enabled = BR_KERNEL_STP;
148 br_debug(br, "using kernel STP\n");
149
150 /* To start timers on any ports left in blocking */
151 br_port_state_selection(br);
152 }
153
154 spin_unlock_bh(&br->lock);
155 }
156
br_stp_stop(struct net_bridge * br)157 static void br_stp_stop(struct net_bridge *br)
158 {
159 int r;
160 char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL };
161 char *envp[] = { NULL };
162
163 if (br->stp_enabled == BR_USER_STP) {
164 r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
165 br_info(br, "userspace STP stopped, return code %d\n", r);
166
167 /* To start timers on any ports left in blocking */
168 spin_lock_bh(&br->lock);
169 br_port_state_selection(br);
170 spin_unlock_bh(&br->lock);
171 }
172
173 br->stp_enabled = BR_NO_STP;
174 }
175
br_stp_set_enabled(struct net_bridge * br,unsigned long val)176 void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
177 {
178 ASSERT_RTNL();
179
180 if (val) {
181 if (br->stp_enabled == BR_NO_STP)
182 br_stp_start(br);
183 } else {
184 if (br->stp_enabled != BR_NO_STP)
185 br_stp_stop(br);
186 }
187 }
188
189 /* called under bridge lock */
br_stp_change_bridge_id(struct net_bridge * br,const unsigned char * addr)190 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
191 {
192 /* should be aligned on 2 bytes for ether_addr_equal() */
193 unsigned short oldaddr_aligned[ETH_ALEN >> 1];
194 unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
195 struct net_bridge_port *p;
196 int wasroot;
197
198 wasroot = br_is_root_bridge(br);
199
200 br_fdb_change_mac_address(br, addr);
201
202 memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
203 memcpy(br->bridge_id.addr, addr, ETH_ALEN);
204 memcpy(br->dev->dev_addr, addr, ETH_ALEN);
205
206 list_for_each_entry(p, &br->port_list, list) {
207 if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
208 memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
209
210 if (ether_addr_equal(p->designated_root.addr, oldaddr))
211 memcpy(p->designated_root.addr, addr, ETH_ALEN);
212 }
213
214 br_configuration_update(br);
215 br_port_state_selection(br);
216 if (br_is_root_bridge(br) && !wasroot)
217 br_become_root_bridge(br);
218 }
219
220 /* should be aligned on 2 bytes for ether_addr_equal() */
221 static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
222
223 /* called under bridge lock */
br_stp_recalculate_bridge_id(struct net_bridge * br)224 bool br_stp_recalculate_bridge_id(struct net_bridge *br)
225 {
226 const unsigned char *br_mac_zero =
227 (const unsigned char *)br_mac_zero_aligned;
228 const unsigned char *addr = br_mac_zero;
229 struct net_bridge_port *p;
230
231 /* user has chosen a value so keep it */
232 if (br->dev->addr_assign_type == NET_ADDR_SET)
233 return false;
234
235 list_for_each_entry(p, &br->port_list, list) {
236 if (addr == br_mac_zero ||
237 memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
238 addr = p->dev->dev_addr;
239
240 }
241
242 if (ether_addr_equal(br->bridge_id.addr, addr))
243 return false; /* no change */
244
245 br_stp_change_bridge_id(br, addr);
246 return true;
247 }
248
249 /* Acquires and releases bridge lock */
br_stp_set_bridge_priority(struct net_bridge * br,u16 newprio)250 void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
251 {
252 struct net_bridge_port *p;
253 int wasroot;
254
255 spin_lock_bh(&br->lock);
256 wasroot = br_is_root_bridge(br);
257
258 list_for_each_entry(p, &br->port_list, list) {
259 if (p->state != BR_STATE_DISABLED &&
260 br_is_designated_port(p)) {
261 p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
262 p->designated_bridge.prio[1] = newprio & 0xFF;
263 }
264
265 }
266
267 br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
268 br->bridge_id.prio[1] = newprio & 0xFF;
269 br_configuration_update(br);
270 br_port_state_selection(br);
271 if (br_is_root_bridge(br) && !wasroot)
272 br_become_root_bridge(br);
273 spin_unlock_bh(&br->lock);
274 }
275
276 /* called under bridge lock */
br_stp_set_port_priority(struct net_bridge_port * p,unsigned long newprio)277 int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
278 {
279 port_id new_port_id;
280
281 if (newprio > BR_MAX_PORT_PRIORITY)
282 return -ERANGE;
283
284 new_port_id = br_make_port_id(newprio, p->port_no);
285 if (br_is_designated_port(p))
286 p->designated_port = new_port_id;
287
288 p->port_id = new_port_id;
289 p->priority = newprio;
290 if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
291 p->port_id < p->designated_port) {
292 br_become_designated_port(p);
293 br_port_state_selection(p->br);
294 }
295
296 return 0;
297 }
298
299 /* called under bridge lock */
br_stp_set_path_cost(struct net_bridge_port * p,unsigned long path_cost)300 int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
301 {
302 if (path_cost < BR_MIN_PATH_COST ||
303 path_cost > BR_MAX_PATH_COST)
304 return -ERANGE;
305
306 p->flags |= BR_ADMIN_COST;
307 p->path_cost = path_cost;
308 br_configuration_update(p->br);
309 br_port_state_selection(p->br);
310 return 0;
311 }
312
br_show_bridge_id(char * buf,const struct bridge_id * id)313 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
314 {
315 return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
316 id->prio[0], id->prio[1],
317 id->addr[0], id->addr[1], id->addr[2],
318 id->addr[3], id->addr[4], id->addr[5]);
319 }
320