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Linux/net/bridge/br_stp_if.c

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  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 #include <net/switchdev.h>
 19 
 20 #include "br_private.h"
 21 #include "br_private_stp.h"
 22 
 23 
 24 /* Port id is composed of priority and port number.
 25  * NB: some bits of priority are dropped to
 26  *     make room for more ports.
 27  */
 28 static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
 29 {
 30         return ((u16)priority << BR_PORT_BITS)
 31                 | (port_no & ((1<<BR_PORT_BITS)-1));
 32 }
 33 
 34 #define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)
 35 
 36 /* called under bridge lock */
 37 void br_init_port(struct net_bridge_port *p)
 38 {
 39         int err;
 40 
 41         p->port_id = br_make_port_id(p->priority, p->port_no);
 42         br_become_designated_port(p);
 43         br_set_state(p, BR_STATE_BLOCKING);
 44         p->topology_change_ack = 0;
 45         p->config_pending = 0;
 46 
 47         err = __set_ageing_time(p->dev, p->br->ageing_time);
 48         if (err)
 49                 netdev_err(p->dev, "failed to offload ageing time\n");
 50 }
 51 
 52 /* NO locks held */
 53 void br_stp_enable_bridge(struct net_bridge *br)
 54 {
 55         struct net_bridge_port *p;
 56 
 57         spin_lock_bh(&br->lock);
 58         if (br->stp_enabled == BR_KERNEL_STP)
 59                 mod_timer(&br->hello_timer, jiffies + br->hello_time);
 60         mod_delayed_work(system_long_wq, &br->gc_work, HZ / 10);
 61 
 62         br_config_bpdu_generation(br);
 63 
 64         list_for_each_entry(p, &br->port_list, list) {
 65                 if (netif_running(p->dev) && netif_oper_up(p->dev))
 66                         br_stp_enable_port(p);
 67 
 68         }
 69         spin_unlock_bh(&br->lock);
 70 }
 71 
 72 /* NO locks held */
 73 void br_stp_disable_bridge(struct net_bridge *br)
 74 {
 75         struct net_bridge_port *p;
 76 
 77         spin_lock_bh(&br->lock);
 78         list_for_each_entry(p, &br->port_list, list) {
 79                 if (p->state != BR_STATE_DISABLED)
 80                         br_stp_disable_port(p);
 81 
 82         }
 83 
 84         __br_set_topology_change(br, 0);
 85         br->topology_change_detected = 0;
 86         spin_unlock_bh(&br->lock);
 87 
 88         del_timer_sync(&br->hello_timer);
 89         del_timer_sync(&br->topology_change_timer);
 90         del_timer_sync(&br->tcn_timer);
 91         cancel_delayed_work_sync(&br->gc_work);
 92 }
 93 
 94 /* called under bridge lock */
 95 void br_stp_enable_port(struct net_bridge_port *p)
 96 {
 97         br_init_port(p);
 98         br_port_state_selection(p->br);
 99         br_ifinfo_notify(RTM_NEWLINK, p);
100 }
101 
102 /* called under bridge lock */
103 void br_stp_disable_port(struct net_bridge_port *p)
104 {
105         struct net_bridge *br = p->br;
106         int wasroot;
107 
108         wasroot = br_is_root_bridge(br);
109         br_become_designated_port(p);
110         br_set_state(p, BR_STATE_DISABLED);
111         p->topology_change_ack = 0;
112         p->config_pending = 0;
113 
114         br_ifinfo_notify(RTM_NEWLINK, p);
115 
116         del_timer(&p->message_age_timer);
117         del_timer(&p->forward_delay_timer);
118         del_timer(&p->hold_timer);
119 
120         br_fdb_delete_by_port(br, p, 0, 0);
121         br_multicast_disable_port(p);
122 
123         br_configuration_update(br);
124 
125         br_port_state_selection(br);
126 
127         if (br_is_root_bridge(br) && !wasroot)
128                 br_become_root_bridge(br);
129 }
130 
131 static int br_stp_call_user(struct net_bridge *br, char *arg)
132 {
133         char *argv[] = { BR_STP_PROG, br->dev->name, arg, NULL };
134         char *envp[] = { NULL };
135         int rc;
136 
137         /* call userspace STP and report program errors */
138         rc = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
139         if (rc > 0) {
140                 if (rc & 0xff)
141                         br_debug(br, BR_STP_PROG " received signal %d\n",
142                                  rc & 0x7f);
143                 else
144                         br_debug(br, BR_STP_PROG " exited with code %d\n",
145                                  (rc >> 8) & 0xff);
146         }
147 
148         return rc;
149 }
150 
151 static void br_stp_start(struct net_bridge *br)
152 {
153         struct net_bridge_port *p;
154         int err = -ENOENT;
155 
156         if (net_eq(dev_net(br->dev), &init_net))
157                 err = br_stp_call_user(br, "start");
158 
159         if (err && err != -ENOENT)
160                 br_err(br, "failed to start userspace STP (%d)\n", err);
161 
162         spin_lock_bh(&br->lock);
163 
164         if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)
165                 __br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);
166         else if (br->bridge_forward_delay > BR_MAX_FORWARD_DELAY)
167                 __br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);
168 
169         if (!err) {
170                 br->stp_enabled = BR_USER_STP;
171                 br_debug(br, "userspace STP started\n");
172 
173                 /* Stop hello and hold timers */
174                 del_timer(&br->hello_timer);
175                 list_for_each_entry(p, &br->port_list, list)
176                         del_timer(&p->hold_timer);
177         } else {
178                 br->stp_enabled = BR_KERNEL_STP;
179                 br_debug(br, "using kernel STP\n");
180 
181                 /* To start timers on any ports left in blocking */
182                 if (br->dev->flags & IFF_UP)
183                         mod_timer(&br->hello_timer, jiffies + br->hello_time);
184                 br_port_state_selection(br);
185         }
186 
187         spin_unlock_bh(&br->lock);
188 }
189 
190 static void br_stp_stop(struct net_bridge *br)
191 {
192         struct net_bridge_port *p;
193         int err;
194 
195         if (br->stp_enabled == BR_USER_STP) {
196                 err = br_stp_call_user(br, "stop");
197                 if (err)
198                         br_err(br, "failed to stop userspace STP (%d)\n", err);
199 
200                 /* To start timers on any ports left in blocking */
201                 mod_timer(&br->hello_timer, jiffies + br->hello_time);
202                 list_for_each_entry(p, &br->port_list, list)
203                         mod_timer(&p->hold_timer,
204                                   round_jiffies(jiffies + BR_HOLD_TIME));
205                 spin_lock_bh(&br->lock);
206                 br_port_state_selection(br);
207                 spin_unlock_bh(&br->lock);
208         }
209 
210         br->stp_enabled = BR_NO_STP;
211 }
212 
213 void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
214 {
215         ASSERT_RTNL();
216 
217         if (val) {
218                 if (br->stp_enabled == BR_NO_STP)
219                         br_stp_start(br);
220         } else {
221                 if (br->stp_enabled != BR_NO_STP)
222                         br_stp_stop(br);
223         }
224 }
225 
226 /* called under bridge lock */
227 void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
228 {
229         /* should be aligned on 2 bytes for ether_addr_equal() */
230         unsigned short oldaddr_aligned[ETH_ALEN >> 1];
231         unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
232         struct net_bridge_port *p;
233         int wasroot;
234 
235         wasroot = br_is_root_bridge(br);
236 
237         br_fdb_change_mac_address(br, addr);
238 
239         memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
240         memcpy(br->bridge_id.addr, addr, ETH_ALEN);
241         memcpy(br->dev->dev_addr, addr, ETH_ALEN);
242 
243         list_for_each_entry(p, &br->port_list, list) {
244                 if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
245                         memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
246 
247                 if (ether_addr_equal(p->designated_root.addr, oldaddr))
248                         memcpy(p->designated_root.addr, addr, ETH_ALEN);
249         }
250 
251         br_configuration_update(br);
252         br_port_state_selection(br);
253         if (br_is_root_bridge(br) && !wasroot)
254                 br_become_root_bridge(br);
255 }
256 
257 /* should be aligned on 2 bytes for ether_addr_equal() */
258 static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
259 
260 /* called under bridge lock */
261 bool br_stp_recalculate_bridge_id(struct net_bridge *br)
262 {
263         const unsigned char *br_mac_zero =
264                         (const unsigned char *)br_mac_zero_aligned;
265         const unsigned char *addr = br_mac_zero;
266         struct net_bridge_port *p;
267 
268         /* user has chosen a value so keep it */
269         if (br->dev->addr_assign_type == NET_ADDR_SET)
270                 return false;
271 
272         list_for_each_entry(p, &br->port_list, list) {
273                 if (addr == br_mac_zero ||
274                     memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
275                         addr = p->dev->dev_addr;
276 
277         }
278 
279         if (ether_addr_equal(br->bridge_id.addr, addr))
280                 return false;   /* no change */
281 
282         br_stp_change_bridge_id(br, addr);
283         return true;
284 }
285 
286 /* Acquires and releases bridge lock */
287 void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
288 {
289         struct net_bridge_port *p;
290         int wasroot;
291 
292         spin_lock_bh(&br->lock);
293         wasroot = br_is_root_bridge(br);
294 
295         list_for_each_entry(p, &br->port_list, list) {
296                 if (p->state != BR_STATE_DISABLED &&
297                     br_is_designated_port(p)) {
298                         p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
299                         p->designated_bridge.prio[1] = newprio & 0xFF;
300                 }
301 
302         }
303 
304         br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
305         br->bridge_id.prio[1] = newprio & 0xFF;
306         br_configuration_update(br);
307         br_port_state_selection(br);
308         if (br_is_root_bridge(br) && !wasroot)
309                 br_become_root_bridge(br);
310         spin_unlock_bh(&br->lock);
311 }
312 
313 /* called under bridge lock */
314 int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
315 {
316         port_id new_port_id;
317 
318         if (newprio > BR_MAX_PORT_PRIORITY)
319                 return -ERANGE;
320 
321         new_port_id = br_make_port_id(newprio, p->port_no);
322         if (br_is_designated_port(p))
323                 p->designated_port = new_port_id;
324 
325         p->port_id = new_port_id;
326         p->priority = newprio;
327         if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
328             p->port_id < p->designated_port) {
329                 br_become_designated_port(p);
330                 br_port_state_selection(p->br);
331         }
332 
333         return 0;
334 }
335 
336 /* called under bridge lock */
337 int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
338 {
339         if (path_cost < BR_MIN_PATH_COST ||
340             path_cost > BR_MAX_PATH_COST)
341                 return -ERANGE;
342 
343         p->flags |= BR_ADMIN_COST;
344         p->path_cost = path_cost;
345         br_configuration_update(p->br);
346         br_port_state_selection(p->br);
347         return 0;
348 }
349 
350 ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
351 {
352         return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
353                id->prio[0], id->prio[1],
354                id->addr[0], id->addr[1], id->addr[2],
355                id->addr[3], id->addr[4], id->addr[5]);
356 }
357 

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