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 <linux/slab.h>
19 #include <linux/pkt_sched.h>
20 #include <net/net_namespace.h>
22 #include <net/llc_pdu.h>
24 #include <asm/unaligned.h>
26 #include "br_private.h"
27 #include "br_private_stp.h"
31 #define LLC_RESERVE sizeof(struct llc_pdu_un)
33 static void br_send_bpdu(struct net_bridge_port
*p
,
34 const unsigned char *data
, int length
)
38 skb
= dev_alloc_skb(length
+LLC_RESERVE
);
43 skb
->protocol
= htons(ETH_P_802_2
);
44 skb
->priority
= TC_PRIO_CONTROL
;
46 skb_reserve(skb
, LLC_RESERVE
);
47 memcpy(__skb_put(skb
, length
), data
, length
);
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
);
53 llc_mac_hdr_init(skb
, p
->dev
->dev_addr
, p
->br
->group_addr
);
55 skb_reset_mac_header(skb
);
57 NF_HOOK(NFPROTO_BRIDGE
, NF_BR_LOCAL_OUT
, skb
, NULL
, skb
->dev
,
61 static inline void br_set_ticks(unsigned char *dest
, int j
)
63 unsigned long ticks
= (STP_HZ
* j
)/ HZ
;
65 put_unaligned_be16(ticks
, dest
);
68 static inline int br_get_ticks(const unsigned char *src
)
70 unsigned long ticks
= get_unaligned_be16(src
);
72 return DIV_ROUND_UP(ticks
* HZ
, STP_HZ
);
75 /* called under bridge lock */
76 void br_send_config_bpdu(struct net_bridge_port
*p
, struct br_config_bpdu
*bpdu
)
78 unsigned char buf
[35];
80 if (p
->br
->stp_enabled
!= BR_KERNEL_STP
)
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;
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
);
117 br_send_bpdu(p
, buf
, 35);
120 /* called under bridge lock */
121 void br_send_tcn_bpdu(struct net_bridge_port
*p
)
123 unsigned char buf
[4];
125 if (p
->br
->stp_enabled
!= BR_KERNEL_STP
)
131 buf
[3] = BPDU_TYPE_TCN
;
132 br_send_bpdu(p
, buf
, 4);
138 * NO locks, but rcu_read_lock
140 void br_stp_rcv(const struct stp_proto
*proto
, struct sk_buff
*skb
,
141 struct net_device
*dev
)
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
;
148 if (!pskb_may_pull(skb
, 4))
151 /* compare of protocol id and version */
153 if (buf
[0] != 0 || buf
[1] != 0 || buf
[2] != 0)
156 p
= br_port_get_check_rcu(dev
);
161 spin_lock(&br
->lock
);
163 if (br
->stp_enabled
!= BR_KERNEL_STP
)
166 if (!(br
->dev
->flags
& IFF_UP
))
169 if (p
->state
== BR_STATE_DISABLED
)
172 if (!ether_addr_equal(dest
, br
->group_addr
))
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
);
182 buf
= skb_pull(skb
, 3);
184 if (buf
[0] == BPDU_TYPE_CONFIG
) {
185 struct br_config_bpdu bpdu
;
187 if (!pskb_may_pull(skb
, 32))
191 bpdu
.topology_change
= (buf
[1] & 0x01) ? 1 : 0;
192 bpdu
.topology_change_ack
= (buf
[1] & 0x80) ? 1 : 0;
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
=
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];
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);
222 if (bpdu
.message_age
> bpdu
.max_age
) {
225 "port %u config from %pM"
226 " (message_age %ul > max_age %ul)\n",
228 eth_hdr(skb
)->h_source
,
229 bpdu
.message_age
, bpdu
.max_age
);
233 br_received_config_bpdu(p
, &bpdu
);
234 } else if (buf
[0] == BPDU_TYPE_TCN
) {
235 br_received_tcn_bpdu(p
);
238 spin_unlock(&br
->lock
);