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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Spanning tree protocol; BPDU handling
3 * Linux ethernet bridge
4 *
5 * Authors:
6 * Lennert Buytenhek <buytenh@gnu.org>
7 *
8 * $Id: br_stp_bpdu.c,v 1.3 2001/11/10 02:35:25 davem Exp $
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 */
15
16#include <linux/kernel.h>
17#include <linux/netfilter_bridge.h>
18
19#include "br_private.h"
20#include "br_private_stp.h"
21
22#define JIFFIES_TO_TICKS(j) (((j) << 8) / HZ)
23#define TICKS_TO_JIFFIES(j) (((j) * HZ) >> 8)
24
25static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length)
26{
27 struct net_device *dev;
28 struct sk_buff *skb;
29 int size;
30
31 if (!p->br->stp_enabled)
32 return;
33
34 size = length + 2*ETH_ALEN + 2;
35 if (size < 60)
36 size = 60;
37
38 dev = p->dev;
39
40 if ((skb = dev_alloc_skb(size)) == NULL) {
41 printk(KERN_INFO "br: memory squeeze!\n");
42 return;
43 }
44
45 skb->dev = dev;
46 skb->protocol = htons(ETH_P_802_2);
47 skb->mac.raw = skb_put(skb, size);
48 memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);
49 memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);
50 skb->mac.raw[2*ETH_ALEN] = 0;
51 skb->mac.raw[2*ETH_ALEN+1] = length;
52 skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;
53 memcpy(skb->nh.raw, data, length);
54 memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);
55
56 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
57 dev_queue_xmit);
58}
59
60static __inline__ void br_set_ticks(unsigned char *dest, int jiff)
61{
62 __u16 ticks;
63
64 ticks = JIFFIES_TO_TICKS(jiff);
65 dest[0] = (ticks >> 8) & 0xFF;
66 dest[1] = ticks & 0xFF;
67}
68
69static __inline__ int br_get_ticks(unsigned char *dest)
70{
71 return TICKS_TO_JIFFIES((dest[0] << 8) | dest[1]);
72}
73
74/* called under bridge lock */
75void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
76{
77 unsigned char buf[38];
78
79 buf[0] = 0x42;
80 buf[1] = 0x42;
81 buf[2] = 0x03;
82 buf[3] = 0;
83 buf[4] = 0;
84 buf[5] = 0;
85 buf[6] = BPDU_TYPE_CONFIG;
86 buf[7] = (bpdu->topology_change ? 0x01 : 0) |
87 (bpdu->topology_change_ack ? 0x80 : 0);
88 buf[8] = bpdu->root.prio[0];
89 buf[9] = bpdu->root.prio[1];
90 buf[10] = bpdu->root.addr[0];
91 buf[11] = bpdu->root.addr[1];
92 buf[12] = bpdu->root.addr[2];
93 buf[13] = bpdu->root.addr[3];
94 buf[14] = bpdu->root.addr[4];
95 buf[15] = bpdu->root.addr[5];
96 buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;
97 buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;
98 buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;
99 buf[19] = bpdu->root_path_cost & 0xFF;
100 buf[20] = bpdu->bridge_id.prio[0];
101 buf[21] = bpdu->bridge_id.prio[1];
102 buf[22] = bpdu->bridge_id.addr[0];
103 buf[23] = bpdu->bridge_id.addr[1];
104 buf[24] = bpdu->bridge_id.addr[2];
105 buf[25] = bpdu->bridge_id.addr[3];
106 buf[26] = bpdu->bridge_id.addr[4];
107 buf[27] = bpdu->bridge_id.addr[5];
108 buf[28] = (bpdu->port_id >> 8) & 0xFF;
109 buf[29] = bpdu->port_id & 0xFF;
110
111 br_set_ticks(buf+30, bpdu->message_age);
112 br_set_ticks(buf+32, bpdu->max_age);
113 br_set_ticks(buf+34, bpdu->hello_time);
114 br_set_ticks(buf+36, bpdu->forward_delay);
115
116 br_send_bpdu(p, buf, 38);
117}
118
119/* called under bridge lock */
120void br_send_tcn_bpdu(struct net_bridge_port *p)
121{
122 unsigned char buf[7];
123
124 buf[0] = 0x42;
125 buf[1] = 0x42;
126 buf[2] = 0x03;
127 buf[3] = 0;
128 buf[4] = 0;
129 buf[5] = 0;
130 buf[6] = BPDU_TYPE_TCN;
131 br_send_bpdu(p, buf, 7);
132}
133
134static const unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
135
136/* NO locks */
137int br_stp_handle_bpdu(struct sk_buff *skb)
138{
139 struct net_bridge_port *p = skb->dev->br_port;
140 struct net_bridge *br = p->br;
141 unsigned char *buf;
142
Stephen Hemminger85967bb2005-05-29 14:15:55 -0700143 /* insert into forwarding database after filtering to avoid spoofing */
144 br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
145
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 /* need at least the 802 and STP headers */
147 if (!pskb_may_pull(skb, sizeof(header)+1) ||
148 memcmp(skb->data, header, sizeof(header)))
149 goto err;
150
151 buf = skb_pull(skb, sizeof(header));
152
153 spin_lock_bh(&br->lock);
154 if (p->state == BR_STATE_DISABLED
155 || !(br->dev->flags & IFF_UP)
156 || !br->stp_enabled)
157 goto out;
158
159 if (buf[0] == BPDU_TYPE_CONFIG) {
160 struct br_config_bpdu bpdu;
161
162 if (!pskb_may_pull(skb, 32))
163 goto out;
164
165 buf = skb->data;
166 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
167 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
168
169 bpdu.root.prio[0] = buf[2];
170 bpdu.root.prio[1] = buf[3];
171 bpdu.root.addr[0] = buf[4];
172 bpdu.root.addr[1] = buf[5];
173 bpdu.root.addr[2] = buf[6];
174 bpdu.root.addr[3] = buf[7];
175 bpdu.root.addr[4] = buf[8];
176 bpdu.root.addr[5] = buf[9];
177 bpdu.root_path_cost =
178 (buf[10] << 24) |
179 (buf[11] << 16) |
180 (buf[12] << 8) |
181 buf[13];
182 bpdu.bridge_id.prio[0] = buf[14];
183 bpdu.bridge_id.prio[1] = buf[15];
184 bpdu.bridge_id.addr[0] = buf[16];
185 bpdu.bridge_id.addr[1] = buf[17];
186 bpdu.bridge_id.addr[2] = buf[18];
187 bpdu.bridge_id.addr[3] = buf[19];
188 bpdu.bridge_id.addr[4] = buf[20];
189 bpdu.bridge_id.addr[5] = buf[21];
190 bpdu.port_id = (buf[22] << 8) | buf[23];
191
192 bpdu.message_age = br_get_ticks(buf+24);
193 bpdu.max_age = br_get_ticks(buf+26);
194 bpdu.hello_time = br_get_ticks(buf+28);
195 bpdu.forward_delay = br_get_ticks(buf+30);
196
197 br_received_config_bpdu(p, &bpdu);
198 }
199
200 else if (buf[0] == BPDU_TYPE_TCN) {
201 br_received_tcn_bpdu(p);
202 }
203 out:
204 spin_unlock_bh(&br->lock);
205 err:
206 kfree_skb(skb);
207 return 0;
208}