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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>
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -080018#include <linux/etherdevice.h>
19#include <linux/llc.h>
Stephen Hemminger12ac84c2006-03-20 22:59:49 -080020#include <net/llc.h>
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -080021#include <net/llc_pdu.h>
Peter Chubb4dc6d9c2006-03-23 21:39:47 -080022#include <asm/unaligned.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023
24#include "br_private.h"
25#include "br_private_stp.h"
26
Stephen Hemminger18fdb2b2006-03-20 22:58:49 -080027#define STP_HZ 256
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
Stephen Hemminger12ac84c2006-03-20 22:59:49 -080029#define LLC_RESERVE sizeof(struct llc_pdu_un)
30
31static void br_send_bpdu(struct net_bridge_port *p,
32 const unsigned char *data, int length)
Linus Torvalds1da177e2005-04-16 15:20:36 -070033{
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 struct sk_buff *skb;
Linus Torvalds1da177e2005-04-16 15:20:36 -070035
36 if (!p->br->stp_enabled)
37 return;
38
Stephen Hemminger12ac84c2006-03-20 22:59:49 -080039 skb = dev_alloc_skb(length+LLC_RESERVE);
40 if (!skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
Stephen Hemminger12ac84c2006-03-20 22:59:49 -080043 skb->dev = p->dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 skb->protocol = htons(ETH_P_802_2);
Stephen Hemminger12ac84c2006-03-20 22:59:49 -080045
46 skb_reserve(skb, LLC_RESERVE);
47 memcpy(__skb_put(skb, length), data, length);
48
49 llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
50 LLC_SAP_BSPAN, LLC_PDU_CMD);
51 llc_pdu_init_as_ui_cmd(skb);
52
53 llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
55 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
56 dev_queue_xmit);
57}
58
Stephen Hemminger18fdb2b2006-03-20 22:58:49 -080059static inline void br_set_ticks(unsigned char *dest, int j)
Linus Torvalds1da177e2005-04-16 15:20:36 -070060{
Stephen Hemminger18fdb2b2006-03-20 22:58:49 -080061 unsigned long ticks = (STP_HZ * j)/ HZ;
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
Peter Chubb4dc6d9c2006-03-23 21:39:47 -080063 put_unaligned(htons(ticks), (__be16 *)dest);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064}
65
Stephen Hemminger18fdb2b2006-03-20 22:58:49 -080066static inline int br_get_ticks(const unsigned char *src)
Linus Torvalds1da177e2005-04-16 15:20:36 -070067{
Peter Chubb4dc6d9c2006-03-23 21:39:47 -080068 unsigned long ticks = ntohs(get_unaligned((__be16 *)src));
Stephen Hemminger18fdb2b2006-03-20 22:58:49 -080069
70 return (ticks * HZ + STP_HZ - 1) / STP_HZ;
Linus Torvalds1da177e2005-04-16 15:20:36 -070071}
72
73/* called under bridge lock */
74void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
75{
Stephen Hemminger12ac84c2006-03-20 22:59:49 -080076 unsigned char buf[35];
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
Stephen Hemminger12ac84c2006-03-20 22:59:49 -080078 buf[0] = 0;
79 buf[1] = 0;
80 buf[2] = 0;
81 buf[3] = BPDU_TYPE_CONFIG;
82 buf[4] = (bpdu->topology_change ? 0x01 : 0) |
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 (bpdu->topology_change_ack ? 0x80 : 0);
Stephen Hemminger12ac84c2006-03-20 22:59:49 -080084 buf[5] = bpdu->root.prio[0];
85 buf[6] = bpdu->root.prio[1];
86 buf[7] = bpdu->root.addr[0];
87 buf[8] = bpdu->root.addr[1];
88 buf[9] = bpdu->root.addr[2];
89 buf[10] = bpdu->root.addr[3];
90 buf[11] = bpdu->root.addr[4];
91 buf[12] = bpdu->root.addr[5];
92 buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
93 buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
94 buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
95 buf[16] = bpdu->root_path_cost & 0xFF;
96 buf[17] = bpdu->bridge_id.prio[0];
97 buf[18] = bpdu->bridge_id.prio[1];
98 buf[19] = bpdu->bridge_id.addr[0];
99 buf[20] = bpdu->bridge_id.addr[1];
100 buf[21] = bpdu->bridge_id.addr[2];
101 buf[22] = bpdu->bridge_id.addr[3];
102 buf[23] = bpdu->bridge_id.addr[4];
103 buf[24] = bpdu->bridge_id.addr[5];
104 buf[25] = (bpdu->port_id >> 8) & 0xFF;
105 buf[26] = bpdu->port_id & 0xFF;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
Stephen Hemminger12ac84c2006-03-20 22:59:49 -0800107 br_set_ticks(buf+27, bpdu->message_age);
108 br_set_ticks(buf+29, bpdu->max_age);
109 br_set_ticks(buf+31, bpdu->hello_time);
110 br_set_ticks(buf+33, bpdu->forward_delay);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111
Stephen Hemminger12ac84c2006-03-20 22:59:49 -0800112 br_send_bpdu(p, buf, 35);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113}
114
115/* called under bridge lock */
116void br_send_tcn_bpdu(struct net_bridge_port *p)
117{
Stephen Hemminger12ac84c2006-03-20 22:59:49 -0800118 unsigned char buf[4];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
Stephen Hemminger12ac84c2006-03-20 22:59:49 -0800120 buf[0] = 0;
121 buf[1] = 0;
122 buf[2] = 0;
123 buf[3] = BPDU_TYPE_TCN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 br_send_bpdu(p, buf, 7);
125}
126
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -0800127/*
128 * Called from llc.
129 *
130 * NO locks, but rcu_read_lock (preempt_disabled)
131 */
132int br_stp_rcv(struct sk_buff *skb, struct net_device *dev,
133 struct packet_type *pt, struct net_device *orig_dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134{
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -0800135 const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
136 const unsigned char *dest = eth_hdr(skb)->h_dest;
137 struct net_bridge_port *p = rcu_dereference(dev->br_port);
Stephen Hemmingerb3f1be42006-02-09 17:08:52 -0800138 struct net_bridge *br;
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -0800139 const unsigned char *buf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
Stephen Hemmingerb3f1be42006-02-09 17:08:52 -0800141 if (!p)
142 goto err;
143
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -0800144 if (pdu->ssap != LLC_SAP_BSPAN
145 || pdu->dsap != LLC_SAP_BSPAN
146 || pdu->ctrl_1 != LLC_PDU_TYPE_U)
147 goto err;
148
149 if (!pskb_may_pull(skb, 4))
150 goto err;
151
152 /* compare of protocol id and version */
153 buf = skb->data;
154 if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
155 goto err;
156
Stephen Hemmingerb3f1be42006-02-09 17:08:52 -0800157 br = p->br;
158 spin_lock(&br->lock);
159
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -0800160 if (p->state == BR_STATE_DISABLED
161 || !br->stp_enabled
162 || !(br->dev->flags & IFF_UP))
Stephen Hemmingerb3f1be42006-02-09 17:08:52 -0800163 goto out;
164
Stephen Hemmingerfda93d92006-03-20 22:59:21 -0800165 if (compare_ether_addr(dest, br->group_addr) != 0)
Stephen Hemmingerb3f1be42006-02-09 17:08:52 -0800166 goto out;
Stephen Hemminger85967bb2005-05-29 14:15:55 -0700167
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -0800168 buf = skb_pull(skb, 3);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 if (buf[0] == BPDU_TYPE_CONFIG) {
171 struct br_config_bpdu bpdu;
172
173 if (!pskb_may_pull(skb, 32))
Stephen Hemmingercf0f02d2006-03-20 22:59:06 -0800174 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175
176 buf = skb->data;
177 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
178 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
179
180 bpdu.root.prio[0] = buf[2];
181 bpdu.root.prio[1] = buf[3];
182 bpdu.root.addr[0] = buf[4];
183 bpdu.root.addr[1] = buf[5];
184 bpdu.root.addr[2] = buf[6];
185 bpdu.root.addr[3] = buf[7];
186 bpdu.root.addr[4] = buf[8];
187 bpdu.root.addr[5] = buf[9];
188 bpdu.root_path_cost =
189 (buf[10] << 24) |
190 (buf[11] << 16) |
191 (buf[12] << 8) |
192 buf[13];
193 bpdu.bridge_id.prio[0] = buf[14];
194 bpdu.bridge_id.prio[1] = buf[15];
195 bpdu.bridge_id.addr[0] = buf[16];
196 bpdu.bridge_id.addr[1] = buf[17];
197 bpdu.bridge_id.addr[2] = buf[18];
198 bpdu.bridge_id.addr[3] = buf[19];
199 bpdu.bridge_id.addr[4] = buf[20];
200 bpdu.bridge_id.addr[5] = buf[21];
201 bpdu.port_id = (buf[22] << 8) | buf[23];
202
203 bpdu.message_age = br_get_ticks(buf+24);
204 bpdu.max_age = br_get_ticks(buf+26);
205 bpdu.hello_time = br_get_ticks(buf+28);
206 bpdu.forward_delay = br_get_ticks(buf+30);
207
208 br_received_config_bpdu(p, &bpdu);
209 }
210
211 else if (buf[0] == BPDU_TYPE_TCN) {
212 br_received_tcn_bpdu(p);
213 }
214 out:
Stephen Hemmingerb3f1be42006-02-09 17:08:52 -0800215 spin_unlock(&br->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 err:
217 kfree_skb(skb);
218 return 0;
219}