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	r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
132
133	spin_lock_bh(&br->lock);
134
135	if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)
136		__br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);
137	else if (br->bridge_forward_delay > BR_MAX_FORWARD_DELAY)
138		__br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);
139
140	if (r == 0) {
141		br->stp_enabled = BR_USER_STP;
142		br_debug(br, "userspace STP started\n");
143	} else {
144		br->stp_enabled = BR_KERNEL_STP;
145		br_debug(br, "using kernel STP\n");
146
147		/* To start timers on any ports left in blocking */
148		br_port_state_selection(br);
149	}
150
151	spin_unlock_bh(&br->lock);
152}
153
154static void br_stp_stop(struct net_bridge *br)
155{
156	int r;
157	char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL };
158	char *envp[] = { NULL };
159
160	if (br->stp_enabled == BR_USER_STP) {
161		r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
162		br_info(br, "userspace STP stopped, return code %d\n", r);
163
164		/* To start timers on any ports left in blocking */
165		spin_lock_bh(&br->lock);
166		br_port_state_selection(br);
167		spin_unlock_bh(&br->lock);
168	}
169
170	br->stp_enabled = BR_NO_STP;
171}
172
173void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
174{
175	ASSERT_RTNL();
176
177	if (val) {
178		if (br->stp_enabled == BR_NO_STP)
179			br_stp_start(br);
180	} else {
181		if (br->stp_enabled != BR_NO_STP)
182			br_stp_stop(br);
183	}
184}
185
186/* called under bridge lock */
187void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)
188{
189	/* should be aligned on 2 bytes for ether_addr_equal() */
190	unsigned short oldaddr_aligned[ETH_ALEN >> 1];
191	unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;
192	struct net_bridge_port *p;
193	int wasroot;
194
195	wasroot = br_is_root_bridge(br);
196
197	br_fdb_change_mac_address(br, addr);
198
199	memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
200	memcpy(br->bridge_id.addr, addr, ETH_ALEN);
201	memcpy(br->dev->dev_addr, addr, ETH_ALEN);
202
203	list_for_each_entry(p, &br->port_list, list) {
204		if (ether_addr_equal(p->designated_bridge.addr, oldaddr))
205			memcpy(p->designated_bridge.addr, addr, ETH_ALEN);
206
207		if (ether_addr_equal(p->designated_root.addr, oldaddr))
208			memcpy(p->designated_root.addr, addr, ETH_ALEN);
209	}
210
211	br_configuration_update(br);
212	br_port_state_selection(br);
213	if (br_is_root_bridge(br) && !wasroot)
214		br_become_root_bridge(br);
215}
216
217/* should be aligned on 2 bytes for ether_addr_equal() */
218static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];
219
220/* called under bridge lock */
221bool br_stp_recalculate_bridge_id(struct net_bridge *br)
222{
223	const unsigned char *br_mac_zero =
224			(const unsigned char *)br_mac_zero_aligned;
225	const unsigned char *addr = br_mac_zero;
226	struct net_bridge_port *p;
227
228	/* user has chosen a value so keep it */
229	if (br->dev->addr_assign_type == NET_ADDR_SET)
230		return false;
231
232	list_for_each_entry(p, &br->port_list, list) {
233		if (addr == br_mac_zero ||
234		    memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)
235			addr = p->dev->dev_addr;
236
237	}
238
239	if (ether_addr_equal(br->bridge_id.addr, addr))
240		return false;	/* no change */
241
242	br_stp_change_bridge_id(br, addr);
243	return true;
244}
245
246/* called under bridge lock */
247void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
248{
249	struct net_bridge_port *p;
250	int wasroot;
251
252	wasroot = br_is_root_bridge(br);
253
254	list_for_each_entry(p, &br->port_list, list) {
255		if (p->state != BR_STATE_DISABLED &&
256		    br_is_designated_port(p)) {
257			p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
258			p->designated_bridge.prio[1] = newprio & 0xFF;
259		}
260
261	}
262
263	br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
264	br->bridge_id.prio[1] = newprio & 0xFF;
265	br_configuration_update(br);
266	br_port_state_selection(br);
267	if (br_is_root_bridge(br) && !wasroot)
268		br_become_root_bridge(br);
269}
270
271/* called under bridge lock */
272int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)
273{
274	port_id new_port_id;
275
276	if (newprio > BR_MAX_PORT_PRIORITY)
277		return -ERANGE;
278
279	new_port_id = br_make_port_id(newprio, p->port_no);
280	if (br_is_designated_port(p))
281		p->designated_port = new_port_id;
282
283	p->port_id = new_port_id;
284	p->priority = newprio;
285	if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
286	    p->port_id < p->designated_port) {
287		br_become_designated_port(p);
288		br_port_state_selection(p->br);
289	}
290
291	return 0;
292}
293
294/* called under bridge lock */
295int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)
296{
297	if (path_cost < BR_MIN_PATH_COST ||
298	    path_cost > BR_MAX_PATH_COST)
299		return -ERANGE;
300
301	p->flags |= BR_ADMIN_COST;
302	p->path_cost = path_cost;
303	br_configuration_update(p->br);
304	br_port_state_selection(p->br);
305	return 0;
306}
307
308ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
309{
310	return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x\n",
311	       id->prio[0], id->prio[1],
312	       id->addr[0], id->addr[1], id->addr[2],
313	       id->addr[3], id->addr[4], id->addr[5]);
314}
315