2 * Spanning tree protocol; BPDU handling
3 * Linux ethernet bridge
6 * Lennert Buytenhek <buytenh@gnu.org>
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.
14 #include <linux/kernel.h>
15 #include <linux/netfilter_bridge.h>
16 #include <linux/etherdevice.h>
17 #include <linux/llc.h>
18 #include <net/net_namespace.h>
20 #include <net/llc_pdu.h>
22 #include <asm/unaligned.h>
24 #include "br_private.h"
25 #include "br_private_stp.h"
29 #define LLC_RESERVE sizeof(struct llc_pdu_un)
31 static void br_send_bpdu(struct net_bridge_port
*p
,
32 const unsigned char *data
, int length
)
36 skb
= dev_alloc_skb(length
+LLC_RESERVE
);
41 skb
->protocol
= htons(ETH_P_802_2
);
43 skb_reserve(skb
, LLC_RESERVE
);
44 memcpy(__skb_put(skb
, length
), data
, length
);
46 llc_pdu_header_init(skb
, LLC_PDU_TYPE_U
, LLC_SAP_BSPAN
,
47 LLC_SAP_BSPAN
, LLC_PDU_CMD
);
48 llc_pdu_init_as_ui_cmd(skb
);
50 llc_mac_hdr_init(skb
, p
->dev
->dev_addr
, p
->br
->group_addr
);
52 NF_HOOK(PF_BRIDGE
, NF_BR_LOCAL_OUT
, skb
, NULL
, skb
->dev
,
56 static inline void br_set_ticks(unsigned char *dest
, int j
)
58 unsigned long ticks
= (STP_HZ
* j
)/ HZ
;
60 put_unaligned_be16(ticks
, dest
);
63 static inline int br_get_ticks(const unsigned char *src
)
65 unsigned long ticks
= get_unaligned_be16(src
);
67 return DIV_ROUND_UP(ticks
* HZ
, STP_HZ
);
70 /* called under bridge lock */
71 void br_send_config_bpdu(struct net_bridge_port
*p
, struct br_config_bpdu
*bpdu
)
73 unsigned char buf
[35];
75 if (p
->br
->stp_enabled
!= BR_KERNEL_STP
)
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;
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
);
112 br_send_bpdu(p
, buf
, 35);
115 /* called under bridge lock */
116 void br_send_tcn_bpdu(struct net_bridge_port
*p
)
118 unsigned char buf
[4];
120 if (p
->br
->stp_enabled
!= BR_KERNEL_STP
)
126 buf
[3] = BPDU_TYPE_TCN
;
127 br_send_bpdu(p
, buf
, 4);
133 * NO locks, but rcu_read_lock (preempt_disabled)
135 void br_stp_rcv(const struct stp_proto
*proto
, struct sk_buff
*skb
,
136 struct net_device
*dev
)
138 const unsigned char *dest
= eth_hdr(skb
)->h_dest
;
139 struct net_bridge_port
*p
= rcu_dereference(dev
->br_port
);
140 struct net_bridge
*br
;
141 const unsigned char *buf
;
146 if (!pskb_may_pull(skb
, 4))
149 /* compare of protocol id and version */
151 if (buf
[0] != 0 || buf
[1] != 0 || buf
[2] != 0)
155 spin_lock(&br
->lock
);
157 if (br
->stp_enabled
!= BR_KERNEL_STP
)
160 if (!(br
->dev
->flags
& IFF_UP
))
163 if (p
->state
== BR_STATE_DISABLED
)
166 if (compare_ether_addr(dest
, br
->group_addr
) != 0)
169 buf
= skb_pull(skb
, 3);
171 if (buf
[0] == BPDU_TYPE_CONFIG
) {
172 struct br_config_bpdu bpdu
;
174 if (!pskb_may_pull(skb
, 32))
178 bpdu
.topology_change
= (buf
[1] & 0x01) ? 1 : 0;
179 bpdu
.topology_change_ack
= (buf
[1] & 0x80) ? 1 : 0;
181 bpdu
.root
.prio
[0] = buf
[2];
182 bpdu
.root
.prio
[1] = buf
[3];
183 bpdu
.root
.addr
[0] = buf
[4];
184 bpdu
.root
.addr
[1] = buf
[5];
185 bpdu
.root
.addr
[2] = buf
[6];
186 bpdu
.root
.addr
[3] = buf
[7];
187 bpdu
.root
.addr
[4] = buf
[8];
188 bpdu
.root
.addr
[5] = buf
[9];
189 bpdu
.root_path_cost
=
194 bpdu
.bridge_id
.prio
[0] = buf
[14];
195 bpdu
.bridge_id
.prio
[1] = buf
[15];
196 bpdu
.bridge_id
.addr
[0] = buf
[16];
197 bpdu
.bridge_id
.addr
[1] = buf
[17];
198 bpdu
.bridge_id
.addr
[2] = buf
[18];
199 bpdu
.bridge_id
.addr
[3] = buf
[19];
200 bpdu
.bridge_id
.addr
[4] = buf
[20];
201 bpdu
.bridge_id
.addr
[5] = buf
[21];
202 bpdu
.port_id
= (buf
[22] << 8) | buf
[23];
204 bpdu
.message_age
= br_get_ticks(buf
+24);
205 bpdu
.max_age
= br_get_ticks(buf
+26);
206 bpdu
.hello_time
= br_get_ticks(buf
+28);
207 bpdu
.forward_delay
= br_get_ticks(buf
+30);
209 br_received_config_bpdu(p
, &bpdu
);
212 else if (buf
[0] == BPDU_TYPE_TCN
) {
213 br_received_tcn_bpdu(p
);
216 spin_unlock(&br
->lock
);
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