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 int br_send_bpdu_finish(struct sock *sk, struct sk_buff *skb)
35 return dev_queue_xmit(skb);
38 static void br_send_bpdu(struct net_bridge_port *p,
39 const unsigned char *data, int length)
43 skb = dev_alloc_skb(length+LLC_RESERVE);
48 skb->protocol = htons(ETH_P_802_2);
49 skb->priority = TC_PRIO_CONTROL;
51 skb_reserve(skb, LLC_RESERVE);
52 memcpy(__skb_put(skb, length), data, length);
54 llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
55 LLC_SAP_BSPAN, LLC_PDU_CMD);
56 llc_pdu_init_as_ui_cmd(skb);
58 llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
60 skb_reset_mac_header(skb);
62 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, NULL, skb,
67 static inline void br_set_ticks(unsigned char *dest, int j)
69 unsigned long ticks = (STP_HZ * j)/ HZ;
71 put_unaligned_be16(ticks, dest);
74 static inline int br_get_ticks(const unsigned char *src)
76 unsigned long ticks = get_unaligned_be16(src);
78 return DIV_ROUND_UP(ticks * HZ, STP_HZ);
81 /* called under bridge lock */
82 void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
84 unsigned char buf[35];
86 if (p->br->stp_enabled != BR_KERNEL_STP)
92 buf[3] = BPDU_TYPE_CONFIG;
93 buf[4] = (bpdu->topology_change ? 0x01 : 0) |
94 (bpdu->topology_change_ack ? 0x80 : 0);
95 buf[5] = bpdu->root.prio[0];
96 buf[6] = bpdu->root.prio[1];
97 buf[7] = bpdu->root.addr[0];
98 buf[8] = bpdu->root.addr[1];
99 buf[9] = bpdu->root.addr[2];
100 buf[10] = bpdu->root.addr[3];
101 buf[11] = bpdu->root.addr[4];
102 buf[12] = bpdu->root.addr[5];
103 buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
104 buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
105 buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
106 buf[16] = bpdu->root_path_cost & 0xFF;
107 buf[17] = bpdu->bridge_id.prio[0];
108 buf[18] = bpdu->bridge_id.prio[1];
109 buf[19] = bpdu->bridge_id.addr[0];
110 buf[20] = bpdu->bridge_id.addr[1];
111 buf[21] = bpdu->bridge_id.addr[2];
112 buf[22] = bpdu->bridge_id.addr[3];
113 buf[23] = bpdu->bridge_id.addr[4];
114 buf[24] = bpdu->bridge_id.addr[5];
115 buf[25] = (bpdu->port_id >> 8) & 0xFF;
116 buf[26] = bpdu->port_id & 0xFF;
118 br_set_ticks(buf+27, bpdu->message_age);
119 br_set_ticks(buf+29, bpdu->max_age);
120 br_set_ticks(buf+31, bpdu->hello_time);
121 br_set_ticks(buf+33, bpdu->forward_delay);
123 br_send_bpdu(p, buf, 35);
126 /* called under bridge lock */
127 void br_send_tcn_bpdu(struct net_bridge_port *p)
129 unsigned char buf[4];
131 if (p->br->stp_enabled != BR_KERNEL_STP)
137 buf[3] = BPDU_TYPE_TCN;
138 br_send_bpdu(p, buf, 4);
144 * NO locks, but rcu_read_lock
146 void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
147 struct net_device *dev)
149 const unsigned char *dest = eth_hdr(skb)->h_dest;
150 struct net_bridge_port *p;
151 struct net_bridge *br;
152 const unsigned char *buf;
154 if (!pskb_may_pull(skb, 4))
157 /* compare of protocol id and version */
159 if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
162 p = br_port_get_check_rcu(dev);
167 spin_lock(&br->lock);
169 if (br->stp_enabled != BR_KERNEL_STP)
172 if (!(br->dev->flags & IFF_UP))
175 if (p->state == BR_STATE_DISABLED)
178 if (!ether_addr_equal(dest, br->group_addr))
181 if (p->flags & BR_BPDU_GUARD) {
182 br_notice(br, "BPDU received on blocked port %u(%s)\n",
183 (unsigned int) p->port_no, p->dev->name);
184 br_stp_disable_port(p);
188 buf = skb_pull(skb, 3);
190 if (buf[0] == BPDU_TYPE_CONFIG) {
191 struct br_config_bpdu bpdu;
193 if (!pskb_may_pull(skb, 32))
197 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
198 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
200 bpdu.root.prio[0] = buf[2];
201 bpdu.root.prio[1] = buf[3];
202 bpdu.root.addr[0] = buf[4];
203 bpdu.root.addr[1] = buf[5];
204 bpdu.root.addr[2] = buf[6];
205 bpdu.root.addr[3] = buf[7];
206 bpdu.root.addr[4] = buf[8];
207 bpdu.root.addr[5] = buf[9];
208 bpdu.root_path_cost =
213 bpdu.bridge_id.prio[0] = buf[14];
214 bpdu.bridge_id.prio[1] = buf[15];
215 bpdu.bridge_id.addr[0] = buf[16];
216 bpdu.bridge_id.addr[1] = buf[17];
217 bpdu.bridge_id.addr[2] = buf[18];
218 bpdu.bridge_id.addr[3] = buf[19];
219 bpdu.bridge_id.addr[4] = buf[20];
220 bpdu.bridge_id.addr[5] = buf[21];
221 bpdu.port_id = (buf[22] << 8) | buf[23];
223 bpdu.message_age = br_get_ticks(buf+24);
224 bpdu.max_age = br_get_ticks(buf+26);
225 bpdu.hello_time = br_get_ticks(buf+28);
226 bpdu.forward_delay = br_get_ticks(buf+30);
228 if (bpdu.message_age > bpdu.max_age) {
231 "port %u config from %pM"
232 " (message_age %ul > max_age %ul)\n",
234 eth_hdr(skb)->h_source,
235 bpdu.message_age, bpdu.max_age);
239 br_received_config_bpdu(p, &bpdu);
240 } else if (buf[0] == BPDU_TYPE_TCN) {
241 br_received_tcn_bpdu(p);
244 spin_unlock(&br->lock);