1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
/*
* Spanning tree protocol; BPDU handling
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*
* $Id: br_stp_bpdu.c,v 1.3 2001/11/10 02:35:25 davem Exp $
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/netfilter_bridge.h>
#include "br_private.h"
#include "br_private_stp.h"
#define STP_HZ 256
static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length)
{
struct net_device *dev;
struct sk_buff *skb;
int size;
if (!p->br->stp_enabled)
return;
size = length + 2*ETH_ALEN + 2;
if (size < 60)
size = 60;
dev = p->dev;
if ((skb = dev_alloc_skb(size)) == NULL) {
printk(KERN_INFO "br: memory squeeze!\n");
return;
}
skb->dev = dev;
skb->protocol = htons(ETH_P_802_2);
skb->mac.raw = skb_put(skb, size);
memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);
memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);
skb->mac.raw[2*ETH_ALEN] = 0;
skb->mac.raw[2*ETH_ALEN+1] = length;
skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;
memcpy(skb->nh.raw, data, length);
memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);
NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
dev_queue_xmit);
}
static inline void br_set_ticks(unsigned char *dest, int j)
{
unsigned long ticks = (STP_HZ * j)/ HZ;
*((__be16 *) dest) = htons(ticks);
}
static inline int br_get_ticks(const unsigned char *src)
{
unsigned long ticks = ntohs(*(__be16 *)src);
return (ticks * HZ + STP_HZ - 1) / STP_HZ;
}
/* called under bridge lock */
void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
unsigned char buf[38];
buf[0] = 0x42;
buf[1] = 0x42;
buf[2] = 0x03;
buf[3] = 0;
buf[4] = 0;
buf[5] = 0;
buf[6] = BPDU_TYPE_CONFIG;
buf[7] = (bpdu->topology_change ? 0x01 : 0) |
(bpdu->topology_change_ack ? 0x80 : 0);
buf[8] = bpdu->root.prio[0];
buf[9] = bpdu->root.prio[1];
buf[10] = bpdu->root.addr[0];
buf[11] = bpdu->root.addr[1];
buf[12] = bpdu->root.addr[2];
buf[13] = bpdu->root.addr[3];
buf[14] = bpdu->root.addr[4];
buf[15] = bpdu->root.addr[5];
buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;
buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;
buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;
buf[19] = bpdu->root_path_cost & 0xFF;
buf[20] = bpdu->bridge_id.prio[0];
buf[21] = bpdu->bridge_id.prio[1];
buf[22] = bpdu->bridge_id.addr[0];
buf[23] = bpdu->bridge_id.addr[1];
buf[24] = bpdu->bridge_id.addr[2];
buf[25] = bpdu->bridge_id.addr[3];
buf[26] = bpdu->bridge_id.addr[4];
buf[27] = bpdu->bridge_id.addr[5];
buf[28] = (bpdu->port_id >> 8) & 0xFF;
buf[29] = bpdu->port_id & 0xFF;
br_set_ticks(buf+30, bpdu->message_age);
br_set_ticks(buf+32, bpdu->max_age);
br_set_ticks(buf+34, bpdu->hello_time);
br_set_ticks(buf+36, bpdu->forward_delay);
br_send_bpdu(p, buf, 38);
}
/* called under bridge lock */
void br_send_tcn_bpdu(struct net_bridge_port *p)
{
unsigned char buf[7];
buf[0] = 0x42;
buf[1] = 0x42;
buf[2] = 0x03;
buf[3] = 0;
buf[4] = 0;
buf[5] = 0;
buf[6] = BPDU_TYPE_TCN;
br_send_bpdu(p, buf, 7);
}
static const unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
/* NO locks, but rcu_read_lock (preempt_disabled) */
int br_stp_handle_bpdu(struct sk_buff *skb)
{
struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
struct net_bridge *br;
unsigned char *buf;
if (!p)
goto err;
br = p->br;
spin_lock(&br->lock);
if (p->state == BR_STATE_DISABLED || !(br->dev->flags & IFF_UP))
goto out;
/* insert into forwarding database after filtering to avoid spoofing */
br_fdb_update(br, p, eth_hdr(skb)->h_source);
if (!br->stp_enabled)
goto out;
/* need at least the 802 and STP headers */
if (!pskb_may_pull(skb, sizeof(header)+1) ||
memcmp(skb->data, header, sizeof(header)))
goto out;
buf = skb_pull(skb, sizeof(header));
if (buf[0] == BPDU_TYPE_CONFIG) {
struct br_config_bpdu bpdu;
if (!pskb_may_pull(skb, 32))
goto out;
buf = skb->data;
bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
bpdu.root.prio[0] = buf[2];
bpdu.root.prio[1] = buf[3];
bpdu.root.addr[0] = buf[4];
bpdu.root.addr[1] = buf[5];
bpdu.root.addr[2] = buf[6];
bpdu.root.addr[3] = buf[7];
bpdu.root.addr[4] = buf[8];
bpdu.root.addr[5] = buf[9];
bpdu.root_path_cost =
(buf[10] << 24) |
(buf[11] << 16) |
(buf[12] << 8) |
buf[13];
bpdu.bridge_id.prio[0] = buf[14];
bpdu.bridge_id.prio[1] = buf[15];
bpdu.bridge_id.addr[0] = buf[16];
bpdu.bridge_id.addr[1] = buf[17];
bpdu.bridge_id.addr[2] = buf[18];
bpdu.bridge_id.addr[3] = buf[19];
bpdu.bridge_id.addr[4] = buf[20];
bpdu.bridge_id.addr[5] = buf[21];
bpdu.port_id = (buf[22] << 8) | buf[23];
bpdu.message_age = br_get_ticks(buf+24);
bpdu.max_age = br_get_ticks(buf+26);
bpdu.hello_time = br_get_ticks(buf+28);
bpdu.forward_delay = br_get_ticks(buf+30);
br_received_config_bpdu(p, &bpdu);
}
else if (buf[0] == BPDU_TYPE_TCN) {
br_received_tcn_bpdu(p);
}
out:
spin_unlock(&br->lock);
err:
kfree_skb(skb);
return 0;
}
|
