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 */
27static 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 */
36void 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 */
46void 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 */
65void 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 */
87void 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 */
96void 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
125static 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
157static 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
176void 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 */
190void 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() */
221static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
222
223/* called under bridge lock */
224bool 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 */
250void 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 */
277int 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 */
300int 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
313ssize_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