Merge commit master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 of HEAD
[linux-2.6] / 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  *      $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 #include <linux/etherdevice.h>
19 #include <linux/llc.h>
20 #include <net/llc.h>
21 #include <net/llc_pdu.h>
22 #include <asm/unaligned.h>
23
24 #include "br_private.h"
25 #include "br_private_stp.h"
26
27 #define STP_HZ          256
28
29 #define LLC_RESERVE sizeof(struct llc_pdu_un)
30
31 static void br_send_bpdu(struct net_bridge_port *p,
32                          const unsigned char *data, int length)
33 {
34         struct sk_buff *skb;
35
36         if (!p->br->stp_enabled)
37                 return;
38
39         skb = dev_alloc_skb(length+LLC_RESERVE);
40         if (!skb)
41                 return;
42
43         skb->dev = p->dev;
44         skb->protocol = htons(ETH_P_802_2);
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         NF_HOOK(PF_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(htons(ticks), (__be16 *)dest);
64 }
65
66 static inline int br_get_ticks(const unsigned char *src)
67 {
68         unsigned long ticks = ntohs(get_unaligned((__be16 *)src));
69
70         return (ticks * HZ + STP_HZ - 1) / 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         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) |
83                 (bpdu->topology_change_ack ? 0x80 : 0);
84         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;
106
107         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);
111
112         br_send_bpdu(p, buf, 35);
113 }
114
115 /* called under bridge lock */
116 void br_send_tcn_bpdu(struct net_bridge_port *p)
117 {
118         unsigned char buf[4];
119
120         buf[0] = 0;
121         buf[1] = 0;
122         buf[2] = 0;
123         buf[3] = BPDU_TYPE_TCN;
124         br_send_bpdu(p, buf, 7);
125 }
126
127 /*
128  * Called from llc.
129  *
130  * NO locks, but rcu_read_lock (preempt_disabled)
131  */
132 int br_stp_rcv(struct sk_buff *skb, struct net_device *dev,
133                struct packet_type *pt, struct net_device *orig_dev)
134 {
135         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);
138         struct net_bridge *br;
139         const unsigned char *buf;
140
141         if (!p)
142                 goto err;
143
144         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
157         br = p->br;
158         spin_lock(&br->lock);
159
160         if (p->state == BR_STATE_DISABLED
161             || !br->stp_enabled
162             || !(br->dev->flags & IFF_UP))
163                 goto out;
164
165         if (compare_ether_addr(dest, br->group_addr) != 0)
166                 goto out;
167
168         buf = skb_pull(skb, 3);
169
170         if (buf[0] == BPDU_TYPE_CONFIG) {
171                 struct br_config_bpdu bpdu;
172
173                 if (!pskb_may_pull(skb, 32))
174                         goto out;
175
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:
215         spin_unlock(&br->lock);
216  err:
217         kfree_skb(skb);
218         return 0;
219 }