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1 | /* |
2 | * Spanning tree protocol; BPDU handling |
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/netfilter_bridge.h> |
16 | #include <linux/etherdevice.h> |
17 | #include <linux/llc.h> |
18 | #include <linux/slab.h> |
19 | #include <linux/pkt_sched.h> |
20 | #include <net/net_namespace.h> |
21 | #include <net/llc.h> |
22 | #include <net/llc_pdu.h> |
23 | #include <net/stp.h> |
24 | #include <asm/unaligned.h> |
25 | |
26 | #include "br_private.h" |
27 | #include "br_private_stp.h" |
28 | |
29 | #define STP_HZ 256 |
30 | |
31 | #define LLC_RESERVE sizeof(struct llc_pdu_un) |
32 | |
33 | static void br_send_bpdu(struct net_bridge_port *p, |
34 | const unsigned char *data, int length) |
35 | { |
36 | struct sk_buff *skb; |
37 | |
38 | skb = dev_alloc_skb(length+LLC_RESERVE); |
39 | if (!skb) |
40 | return; |
41 | |
42 | skb->dev = p->dev; |
43 | skb->protocol = htons(ETH_P_802_2); |
44 | skb->priority = TC_PRIO_CONTROL; |
45 | |
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); |
54 | |
55 | skb_reset_mac_header(skb); |
56 | |
57 | NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, |
58 | dev_queue_xmit); |
59 | } |
60 | |
61 | static inline void br_set_ticks(unsigned char *dest, int j) |
62 | { |
63 | unsigned long ticks = (STP_HZ * j)/ HZ; |
64 | |
65 | put_unaligned_be16(ticks, dest); |
66 | } |
67 | |
68 | static inline int br_get_ticks(const unsigned char *src) |
69 | { |
70 | unsigned long ticks = get_unaligned_be16(src); |
71 | |
72 | return DIV_ROUND_UP(ticks * HZ, STP_HZ); |
73 | } |
74 | |
75 | /* called under bridge lock */ |
76 | void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu) |
77 | { |
78 | unsigned char buf[35]; |
79 | |
80 | if (p->br->stp_enabled != BR_KERNEL_STP) |
81 | return; |
82 | |
83 | buf[0] = 0; |
84 | buf[1] = 0; |
85 | buf[2] = 0; |
86 | buf[3] = BPDU_TYPE_CONFIG; |
87 | buf[4] = (bpdu->topology_change ? 0x01 : 0) | |
88 | (bpdu->topology_change_ack ? 0x80 : 0); |
89 | buf[5] = bpdu->root.prio[0]; |
90 | buf[6] = bpdu->root.prio[1]; |
91 | buf[7] = bpdu->root.addr[0]; |
92 | buf[8] = bpdu->root.addr[1]; |
93 | buf[9] = bpdu->root.addr[2]; |
94 | buf[10] = bpdu->root.addr[3]; |
95 | buf[11] = bpdu->root.addr[4]; |
96 | buf[12] = bpdu->root.addr[5]; |
97 | buf[13] = (bpdu->root_path_cost >> 24) & 0xFF; |
98 | buf[14] = (bpdu->root_path_cost >> 16) & 0xFF; |
99 | buf[15] = (bpdu->root_path_cost >> 8) & 0xFF; |
100 | buf[16] = bpdu->root_path_cost & 0xFF; |
101 | buf[17] = bpdu->bridge_id.prio[0]; |
102 | buf[18] = bpdu->bridge_id.prio[1]; |
103 | buf[19] = bpdu->bridge_id.addr[0]; |
104 | buf[20] = bpdu->bridge_id.addr[1]; |
105 | buf[21] = bpdu->bridge_id.addr[2]; |
106 | buf[22] = bpdu->bridge_id.addr[3]; |
107 | buf[23] = bpdu->bridge_id.addr[4]; |
108 | buf[24] = bpdu->bridge_id.addr[5]; |
109 | buf[25] = (bpdu->port_id >> 8) & 0xFF; |
110 | buf[26] = bpdu->port_id & 0xFF; |
111 | |
112 | br_set_ticks(buf+27, bpdu->message_age); |
113 | br_set_ticks(buf+29, bpdu->max_age); |
114 | br_set_ticks(buf+31, bpdu->hello_time); |
115 | br_set_ticks(buf+33, bpdu->forward_delay); |
116 | |
117 | br_send_bpdu(p, buf, 35); |
118 | } |
119 | |
120 | /* called under bridge lock */ |
121 | void br_send_tcn_bpdu(struct net_bridge_port *p) |
122 | { |
123 | unsigned char buf[4]; |
124 | |
125 | if (p->br->stp_enabled != BR_KERNEL_STP) |
126 | return; |
127 | |
128 | buf[0] = 0; |
129 | buf[1] = 0; |
130 | buf[2] = 0; |
131 | buf[3] = BPDU_TYPE_TCN; |
132 | br_send_bpdu(p, buf, 4); |
133 | } |
134 | |
135 | /* |
136 | * Called from llc. |
137 | * |
138 | * NO locks, but rcu_read_lock |
139 | */ |
140 | void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb, |
141 | struct net_device *dev) |
142 | { |
143 | const unsigned char *dest = eth_hdr(skb)->h_dest; |
144 | struct net_bridge_port *p; |
145 | struct net_bridge *br; |
146 | const unsigned char *buf; |
147 | |
148 | if (!pskb_may_pull(skb, 4)) |
149 | goto err; |
150 | |
151 | /* compare of protocol id and version */ |
152 | buf = skb->data; |
153 | if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0) |
154 | goto err; |
155 | |
156 | p = br_port_get_rcu(dev); |
157 | if (!p) |
158 | goto err; |
159 | |
160 | br = p->br; |
161 | spin_lock(&br->lock); |
162 | |
163 | if (br->stp_enabled != BR_KERNEL_STP) |
164 | goto out; |
165 | |
166 | if (!(br->dev->flags & IFF_UP)) |
167 | goto out; |
168 | |
169 | if (p->state == BR_STATE_DISABLED) |
170 | goto out; |
171 | |
172 | if (!ether_addr_equal(dest, br->group_addr)) |
173 | goto out; |
174 | |
175 | if (p->flags & BR_BPDU_GUARD) { |
176 | br_notice(br, "BPDU received on blocked port %u(%s)\n", |
177 | (unsigned int) p->port_no, p->dev->name); |
178 | br_stp_disable_port(p); |
179 | goto out; |
180 | } |
181 | |
182 | buf = skb_pull(skb, 3); |
183 | |
184 | if (buf[0] == BPDU_TYPE_CONFIG) { |
185 | struct br_config_bpdu bpdu; |
186 | |
187 | if (!pskb_may_pull(skb, 32)) |
188 | goto out; |
189 | |
190 | buf = skb->data; |
191 | bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0; |
192 | bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0; |
193 | |
194 | bpdu.root.prio[0] = buf[2]; |
195 | bpdu.root.prio[1] = buf[3]; |
196 | bpdu.root.addr[0] = buf[4]; |
197 | bpdu.root.addr[1] = buf[5]; |
198 | bpdu.root.addr[2] = buf[6]; |
199 | bpdu.root.addr[3] = buf[7]; |
200 | bpdu.root.addr[4] = buf[8]; |
201 | bpdu.root.addr[5] = buf[9]; |
202 | bpdu.root_path_cost = |
203 | (buf[10] << 24) | |
204 | (buf[11] << 16) | |
205 | (buf[12] << 8) | |
206 | buf[13]; |
207 | bpdu.bridge_id.prio[0] = buf[14]; |
208 | bpdu.bridge_id.prio[1] = buf[15]; |
209 | bpdu.bridge_id.addr[0] = buf[16]; |
210 | bpdu.bridge_id.addr[1] = buf[17]; |
211 | bpdu.bridge_id.addr[2] = buf[18]; |
212 | bpdu.bridge_id.addr[3] = buf[19]; |
213 | bpdu.bridge_id.addr[4] = buf[20]; |
214 | bpdu.bridge_id.addr[5] = buf[21]; |
215 | bpdu.port_id = (buf[22] << 8) | buf[23]; |
216 | |
217 | bpdu.message_age = br_get_ticks(buf+24); |
218 | bpdu.max_age = br_get_ticks(buf+26); |
219 | bpdu.hello_time = br_get_ticks(buf+28); |
220 | bpdu.forward_delay = br_get_ticks(buf+30); |
221 | |
222 | if (bpdu.message_age > bpdu.max_age) { |
223 | if (net_ratelimit()) |
224 | br_notice(p->br, |
225 | "port %u config from %pM" |
226 | " (message_age %ul > max_age %ul)\n", |
227 | p->port_no, |
228 | eth_hdr(skb)->h_source, |
229 | bpdu.message_age, bpdu.max_age); |
230 | goto out; |
231 | } |
232 | |
233 | br_received_config_bpdu(p, &bpdu); |
234 | } else if (buf[0] == BPDU_TYPE_TCN) { |
235 | br_received_tcn_bpdu(p); |
236 | } |
237 | out: |
238 | spin_unlock(&br->lock); |
239 | err: |
240 | kfree_skb(skb); |
241 | } |
242 |
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