Root/net/bridge/br_stp_if.c

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/etherdevice.h>
16#include <linux/rtnetlink.h>
17
18#include "br_private.h"
19#include "br_private_stp.h"
20
21
22/* Port id is composed of priority and port number.
23 * NB: least significant bits of priority are dropped to
24 * make room for more ports.
25 */
26static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
27{
28    return ((u16)priority << BR_PORT_BITS)
29        | (port_no & ((1<<BR_PORT_BITS)-1));
30}
31
32/* called under bridge lock */
33void br_init_port(struct net_bridge_port *p)
34{
35    p->port_id = br_make_port_id(p->priority, p->port_no);
36    br_become_designated_port(p);
37    p->state = BR_STATE_BLOCKING;
38    p->topology_change_ack = 0;
39    p->config_pending = 0;
40}
41
42/* called under bridge lock */
43void br_stp_enable_bridge(struct net_bridge *br)
44{
45    struct net_bridge_port *p;
46
47    spin_lock_bh(&br->lock);
48    mod_timer(&br->hello_timer, jiffies + br->hello_time);
49    mod_timer(&br->gc_timer, jiffies + HZ/10);
50
51    br_config_bpdu_generation(br);
52
53    list_for_each_entry(p, &br->port_list, list) {
54        if ((p->dev->flags & IFF_UP) && netif_carrier_ok(p->dev))
55            br_stp_enable_port(p);
56
57    }
58    spin_unlock_bh(&br->lock);
59}
60
61/* NO locks held */
62void br_stp_disable_bridge(struct net_bridge *br)
63{
64    struct net_bridge_port *p;
65
66    spin_lock_bh(&br->lock);
67    list_for_each_entry(p, &br->port_list, list) {
68        if (p->state != BR_STATE_DISABLED)
69            br_stp_disable_port(p);
70
71    }
72
73    br->topology_change = 0;
74    br->topology_change_detected = 0;
75    spin_unlock_bh(&br->lock);
76
77    del_timer_sync(&br->hello_timer);
78    del_timer_sync(&br->topology_change_timer);
79    del_timer_sync(&br->tcn_timer);
80    del_timer_sync(&br->gc_timer);
81}
82
83/* called under bridge lock */
84void br_stp_enable_port(struct net_bridge_port *p)
85{
86    br_init_port(p);
87    br_port_state_selection(p->br);
88    br_log_state(p);
89}
90
91/* called under bridge lock */
92void br_stp_disable_port(struct net_bridge_port *p)
93{
94    struct net_bridge *br = p->br;
95    int wasroot;
96
97    br_log_state(p);
98
99    wasroot = br_is_root_bridge(br);
100    br_become_designated_port(p);
101    p->state = BR_STATE_DISABLED;
102    p->topology_change_ack = 0;
103    p->config_pending = 0;
104
105    del_timer(&p->message_age_timer);
106    del_timer(&p->forward_delay_timer);
107    del_timer(&p->hold_timer);
108
109    br_fdb_delete_by_port(br, p, 0);
110    br_multicast_disable_port(p);
111
112    br_configuration_update(br);
113
114    br_port_state_selection(br);
115
116    if (br_is_root_bridge(br) && !wasroot)
117        br_become_root_bridge(br);
118}
119
120static void br_stp_start(struct net_bridge *br)
121{
122    int r;
123    char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL };
124    char *envp[] = { NULL };
125
126    r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
127    if (r == 0) {
128        br->stp_enabled = BR_USER_STP;
129        br_debug(br, "userspace STP started\n");
130    } else {
131        br->stp_enabled = BR_KERNEL_STP;
132        br_debug(br, "using kernel STP\n");
133
134        /* To start timers on any ports left in blocking */
135        spin_lock_bh(&br->lock);
136        br_port_state_selection(br);
137        spin_unlock_bh(&br->lock);
138    }
139}
140
141static void br_stp_stop(struct net_bridge *br)
142{
143    int r;
144    char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL };
145    char *envp[] = { NULL };
146
147    if (br->stp_enabled == BR_USER_STP) {
148        r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
149        br_info(br, "userspace STP stopped, return code %d\n", r);
150
151        /* To start timers on any ports left in blocking */
152        spin_lock_bh(&br->lock);
153        br_port_state_selection(br);
154        spin_unlock_bh(&br->lock);
155    }
156
157    br->stp_enabled = BR_NO_STP;
158}
159
160void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
161{
162    ASSERT_RTNL();
163
164    if (val) {
165        if (br->stp_enabled == BR_NO_STP)
166            br_stp_start(br);
167    } else {
168        if (br->stp_enabled != BR_NO_STP)
169            br_stp_stop(br);
170    }
171}
172
173/* called under bridge lock */
174void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
175{
176    /* should be aligned on 2 bytes for compare_ether_addr() */
177    unsigned short oldaddr_aligned[ETH_ALEN >> 1];
178    unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
179    struct net_bridge_port *p;
180    int wasroot;
181
182    wasroot = br_is_root_bridge(br);
183
184    memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
185    memcpy(br->bridge_id.addr, addr, ETH_ALEN);
186    memcpy(br->dev->dev_addr, addr, ETH_ALEN);
187
188    list_for_each_entry(p, &br->port_list, list) {
189        if (!compare_ether_addr(p->designated_bridge.addr, oldaddr))
190            memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
191
192        if (!compare_ether_addr(p->designated_root.addr, oldaddr))
193            memcpy(p->designated_root.addr, addr, ETH_ALEN);
194
195    }
196
197    br_configuration_update(br);
198    br_port_state_selection(br);
199    if (br_is_root_bridge(br) && !wasroot)
200        br_become_root_bridge(br);
201}
202
203/* should be aligned on 2 bytes for compare_ether_addr() */
204static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
205
206/* called under bridge lock */
207bool br_stp_recalculate_bridge_id(struct net_bridge *br)
208{
209    const unsigned char *br_mac_zero =
210            (const unsigned char *)br_mac_zero_aligned;
211    const unsigned char *addr = br_mac_zero;
212    struct net_bridge_port *p;
213
214    /* user has chosen a value so keep it */
215    if (br->flags & BR_SET_MAC_ADDR)
216        return false;
217
218    list_for_each_entry(p, &br->port_list, list) {
219        if (addr == br_mac_zero ||
220            memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
221            addr = p->dev->dev_addr;
222
223    }
224
225    if (compare_ether_addr(br->bridge_id.addr, addr) == 0)
226        return false; /* no change */
227
228    br_stp_change_bridge_id(br, addr);
229    return true;
230}
231
232/* called under bridge lock */
233void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
234{
235    struct net_bridge_port *p;
236    int wasroot;
237
238    wasroot = br_is_root_bridge(br);
239
240    list_for_each_entry(p, &br->port_list, list) {
241        if (p->state != BR_STATE_DISABLED &&
242            br_is_designated_port(p)) {
243            p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
244            p->designated_bridge.prio[1] = newprio & 0xFF;
245        }
246
247    }
248
249    br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
250    br->bridge_id.prio[1] = newprio & 0xFF;
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/* called under bridge lock */
258void br_stp_set_port_priority(struct net_bridge_port *p, u8 newprio)
259{
260    port_id new_port_id = br_make_port_id(newprio, p->port_no);
261
262    if (br_is_designated_port(p))
263        p->designated_port = new_port_id;
264
265    p->port_id = new_port_id;
266    p->priority = newprio;
267    if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
268        p->port_id < p->designated_port) {
269        br_become_designated_port(p);
270        br_port_state_selection(p->br);
271    }
272}
273
274/* called under bridge lock */
275void br_stp_set_path_cost(struct net_bridge_port *p, u32 path_cost)
276{
277    p->path_cost = path_cost;
278    br_configuration_update(p->br);
279    br_port_state_selection(p->br);
280}
281
282ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
283{
284    return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
285           id->prio[0], id->prio[1],
286           id->addr[0], id->addr[1], id->addr[2],
287           id->addr[3], id->addr[4], id->addr[5]);
288}
289

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