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Linux/net/bridge/br_stp_if.c

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  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 void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
200 {
201         ASSERT_RTNL();
202 
203         if (val) {
204                 if (br->stp_enabled == BR_NO_STP)
205                         br_stp_start(br);
206         } else {
207                 if (br->stp_enabled != BR_NO_STP)
208                         br_stp_stop(br);
209         }
210 }
211 
212 /* called under bridge lock */
213 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
214 {
215         /* should be aligned on 2 bytes for ether_addr_equal() */
216         unsigned short oldaddr_aligned[ETH_ALEN >> 1];
217         unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
218         struct net_bridge_port *p;
219         int wasroot;
220 
221         wasroot = br_is_root_bridge(br);
222 
223         br_fdb_change_mac_address(br, addr);
224 
225         memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
226         memcpy(br->bridge_id.addr, addr, ETH_ALEN);
227         memcpy(br->dev->dev_addr, addr, ETH_ALEN);
228 
229         list_for_each_entry(p, &br->port_list, list) {
230                 if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
231                         memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
232 
233                 if (ether_addr_equal(p->designated_root.addr, oldaddr))
234                         memcpy(p->designated_root.addr, addr, ETH_ALEN);
235         }
236 
237         br_configuration_update(br);
238         br_port_state_selection(br);
239         if (br_is_root_bridge(br) && !wasroot)
240                 br_become_root_bridge(br);
241 }
242 
243 /* should be aligned on 2 bytes for ether_addr_equal() */
244 static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
245 
246 /* called under bridge lock */
247 bool br_stp_recalculate_bridge_id(struct net_bridge *br)
248 {
249         const unsigned char *br_mac_zero =
250                         (const unsigned char *)br_mac_zero_aligned;
251         const unsigned char *addr = br_mac_zero;
252         struct net_bridge_port *p;
253 
254         /* user has chosen a value so keep it */
255         if (br->dev->addr_assign_type == NET_ADDR_SET)
256                 return false;
257 
258         list_for_each_entry(p, &br->port_list, list) {
259                 if (addr == br_mac_zero ||
260                     memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
261                         addr = p->dev->dev_addr;
262 
263         }
264 
265         if (ether_addr_equal(br->bridge_id.addr, addr))
266                 return false;   /* no change */
267 
268         br_stp_change_bridge_id(br, addr);
269         return true;
270 }
271 
272 /* Acquires and releases bridge lock */
273 void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
274 {
275         struct net_bridge_port *p;
276         int wasroot;
277 
278         spin_lock_bh(&br->lock);
279         wasroot = br_is_root_bridge(br);
280 
281         list_for_each_entry(p, &br->port_list, list) {
282                 if (p->state != BR_STATE_DISABLED &&
283                     br_is_designated_port(p)) {
284                         p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
285                         p->designated_bridge.prio[1] = newprio & 0xFF;
286                 }
287 
288         }
289 
290         br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
291         br->bridge_id.prio[1] = newprio & 0xFF;
292         br_configuration_update(br);
293         br_port_state_selection(br);
294         if (br_is_root_bridge(br) && !wasroot)
295                 br_become_root_bridge(br);
296         spin_unlock_bh(&br->lock);
297 }
298 
299 /* called under bridge lock */
300 int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
301 {
302         port_id new_port_id;
303 
304         if (newprio > BR_MAX_PORT_PRIORITY)
305                 return -ERANGE;
306 
307         new_port_id = br_make_port_id(newprio, p->port_no);
308         if (br_is_designated_port(p))
309                 p->designated_port = new_port_id;
310 
311         p->port_id = new_port_id;
312         p->priority = newprio;
313         if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
314             p->port_id < p->designated_port) {
315                 br_become_designated_port(p);
316                 br_port_state_selection(p->br);
317         }
318 
319         return 0;
320 }
321 
322 /* called under bridge lock */
323 int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
324 {
325         if (path_cost < BR_MIN_PATH_COST ||
326             path_cost > BR_MAX_PATH_COST)
327                 return -ERANGE;
328 
329         p->flags |= BR_ADMIN_COST;
330         p->path_cost = path_cost;
331         br_configuration_update(p->br);
332         br_port_state_selection(p->br);
333         return 0;
334 }
335 
336 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
337 {
338         return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
339                id->prio[0], id->prio[1],
340                id->addr[0], id->addr[1], id->addr[2],
341                id->addr[3], id->addr[4], id->addr[5]);
342 }
343 

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