netns: ebtable: allow unprivileged users to operate ebtables
[linux-3.10.git] / net / bridge / br_stp_bpdu.c
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 <net/net_namespace.h>
20 #include <net/llc.h>
21 #include <net/llc_pdu.h>
22 #include <net/stp.h>
23 #include <asm/unaligned.h>
24
25 #include "br_private.h"
26 #include "br_private_stp.h"
27
28 #define STP_HZ          256
29
30 #define LLC_RESERVE sizeof(struct llc_pdu_un)
31
32 static void br_send_bpdu(struct net_bridge_port *p,
33                          const unsigned char *data, int length)
34 {
35         struct sk_buff *skb;
36
37         skb = dev_alloc_skb(length+LLC_RESERVE);
38         if (!skb)
39                 return;
40
41         skb->dev = p->dev;
42         skb->protocol = htons(ETH_P_802_2);
43
44         skb_reserve(skb, LLC_RESERVE);
45         memcpy(__skb_put(skb, length), data, length);
46
47         llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
48                             LLC_SAP_BSPAN, LLC_PDU_CMD);
49         llc_pdu_init_as_ui_cmd(skb);
50
51         llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
52
53         skb_reset_mac_header(skb);
54
55         NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
56                 dev_queue_xmit);
57 }
58
59 static inline void br_set_ticks(unsigned char *dest, int j)
60 {
61         unsigned long ticks = (STP_HZ * j)/ HZ;
62
63         put_unaligned_be16(ticks, dest);
64 }
65
66 static inline int br_get_ticks(const unsigned char *src)
67 {
68         unsigned long ticks = get_unaligned_be16(src);
69
70         return DIV_ROUND_UP(ticks * HZ, STP_HZ);
71 }
72
73 /* called under bridge lock */
74 void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
75 {
76         unsigned char buf[35];
77
78         if (p->br->stp_enabled != BR_KERNEL_STP)
79                 return;
80
81         buf[0] = 0;
82         buf[1] = 0;
83         buf[2] = 0;
84         buf[3] = BPDU_TYPE_CONFIG;
85         buf[4] = (bpdu->topology_change ? 0x01 : 0) |
86                 (bpdu->topology_change_ack ? 0x80 : 0);
87         buf[5] = bpdu->root.prio[0];
88         buf[6] = bpdu->root.prio[1];
89         buf[7] = bpdu->root.addr[0];
90         buf[8] = bpdu->root.addr[1];
91         buf[9] = bpdu->root.addr[2];
92         buf[10] = bpdu->root.addr[3];
93         buf[11] = bpdu->root.addr[4];
94         buf[12] = bpdu->root.addr[5];
95         buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
96         buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
97         buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
98         buf[16] = bpdu->root_path_cost & 0xFF;
99         buf[17] = bpdu->bridge_id.prio[0];
100         buf[18] = bpdu->bridge_id.prio[1];
101         buf[19] = bpdu->bridge_id.addr[0];
102         buf[20] = bpdu->bridge_id.addr[1];
103         buf[21] = bpdu->bridge_id.addr[2];
104         buf[22] = bpdu->bridge_id.addr[3];
105         buf[23] = bpdu->bridge_id.addr[4];
106         buf[24] = bpdu->bridge_id.addr[5];
107         buf[25] = (bpdu->port_id >> 8) & 0xFF;
108         buf[26] = bpdu->port_id & 0xFF;
109
110         br_set_ticks(buf+27, bpdu->message_age);
111         br_set_ticks(buf+29, bpdu->max_age);
112         br_set_ticks(buf+31, bpdu->hello_time);
113         br_set_ticks(buf+33, bpdu->forward_delay);
114
115         br_send_bpdu(p, buf, 35);
116 }
117
118 /* called under bridge lock */
119 void br_send_tcn_bpdu(struct net_bridge_port *p)
120 {
121         unsigned char buf[4];
122
123         if (p->br->stp_enabled != BR_KERNEL_STP)
124                 return;
125
126         buf[0] = 0;
127         buf[1] = 0;
128         buf[2] = 0;
129         buf[3] = BPDU_TYPE_TCN;
130         br_send_bpdu(p, buf, 4);
131 }
132
133 /*
134  * Called from llc.
135  *
136  * NO locks, but rcu_read_lock
137  */
138 void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
139                 struct net_device *dev)
140 {
141         const unsigned char *dest = eth_hdr(skb)->h_dest;
142         struct net_bridge_port *p;
143         struct net_bridge *br;
144         const unsigned char *buf;
145
146         if (!pskb_may_pull(skb, 4))
147                 goto err;
148
149         /* compare of protocol id and version */
150         buf = skb->data;
151         if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
152                 goto err;
153
154         p = br_port_get_rcu(dev);
155         if (!p)
156                 goto err;
157
158         br = p->br;
159         spin_lock(&br->lock);
160
161         if (br->stp_enabled != BR_KERNEL_STP)
162                 goto out;
163
164         if (!(br->dev->flags & IFF_UP))
165                 goto out;
166
167         if (p->state == BR_STATE_DISABLED)
168                 goto out;
169
170         if (!ether_addr_equal(dest, br->group_addr))
171                 goto out;
172
173         if (p->flags & BR_BPDU_GUARD) {
174                 br_notice(br, "BPDU received on blocked port %u(%s)\n",
175                           (unsigned int) p->port_no, p->dev->name);
176                 br_stp_disable_port(p);
177                 goto out;
178         }
179
180         buf = skb_pull(skb, 3);
181
182         if (buf[0] == BPDU_TYPE_CONFIG) {
183                 struct br_config_bpdu bpdu;
184
185                 if (!pskb_may_pull(skb, 32))
186                         goto out;
187
188                 buf = skb->data;
189                 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
190                 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
191
192                 bpdu.root.prio[0] = buf[2];
193                 bpdu.root.prio[1] = buf[3];
194                 bpdu.root.addr[0] = buf[4];
195                 bpdu.root.addr[1] = buf[5];
196                 bpdu.root.addr[2] = buf[6];
197                 bpdu.root.addr[3] = buf[7];
198                 bpdu.root.addr[4] = buf[8];
199                 bpdu.root.addr[5] = buf[9];
200                 bpdu.root_path_cost =
201                         (buf[10] << 24) |
202                         (buf[11] << 16) |
203                         (buf[12] << 8) |
204                         buf[13];
205                 bpdu.bridge_id.prio[0] = buf[14];
206                 bpdu.bridge_id.prio[1] = buf[15];
207                 bpdu.bridge_id.addr[0] = buf[16];
208                 bpdu.bridge_id.addr[1] = buf[17];
209                 bpdu.bridge_id.addr[2] = buf[18];
210                 bpdu.bridge_id.addr[3] = buf[19];
211                 bpdu.bridge_id.addr[4] = buf[20];
212                 bpdu.bridge_id.addr[5] = buf[21];
213                 bpdu.port_id = (buf[22] << 8) | buf[23];
214
215                 bpdu.message_age = br_get_ticks(buf+24);
216                 bpdu.max_age = br_get_ticks(buf+26);
217                 bpdu.hello_time = br_get_ticks(buf+28);
218                 bpdu.forward_delay = br_get_ticks(buf+30);
219
220                 if (bpdu.message_age > bpdu.max_age) {
221                         if (net_ratelimit())
222                                 br_notice(p->br,
223                                           "port %u config from %pM"
224                                           " (message_age %ul > max_age %ul)\n",
225                                           p->port_no,
226                                           eth_hdr(skb)->h_source,
227                                           bpdu.message_age, bpdu.max_age);
228                         goto out;
229                 }
230
231                 br_received_config_bpdu(p, &bpdu);
232         } else if (buf[0] == BPDU_TYPE_TCN) {
233                 br_received_tcn_bpdu(p);
234         }
235  out:
236         spin_unlock(&br->lock);
237  err:
238         kfree_skb(skb);
239 }