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, NULL, skb,
62 static inline void br_set_ticks(unsigned char *dest, int j)
64 unsigned long ticks = (STP_HZ * j)/ HZ;
66 put_unaligned_be16(ticks, dest);
69 static inline int br_get_ticks(const unsigned char *src)
71 unsigned long ticks = get_unaligned_be16(src);
73 return DIV_ROUND_UP(ticks * HZ, STP_HZ);
76 /* called under bridge lock */
77 void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
79 unsigned char buf[35];
81 if (p->br->stp_enabled != BR_KERNEL_STP)
87 buf[3] = BPDU_TYPE_CONFIG;
88 buf[4] = (bpdu->topology_change ? 0x01 : 0) |
89 (bpdu->topology_change_ack ? 0x80 : 0);
90 buf[5] = bpdu->root.prio[0];
91 buf[6] = bpdu->root.prio[1];
92 buf[7] = bpdu->root.addr[0];
93 buf[8] = bpdu->root.addr[1];
94 buf[9] = bpdu->root.addr[2];
95 buf[10] = bpdu->root.addr[3];
96 buf[11] = bpdu->root.addr[4];
97 buf[12] = bpdu->root.addr[5];
98 buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
99 buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
100 buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
101 buf[16] = bpdu->root_path_cost & 0xFF;
102 buf[17] = bpdu->bridge_id.prio[0];
103 buf[18] = bpdu->bridge_id.prio[1];
104 buf[19] = bpdu->bridge_id.addr[0];
105 buf[20] = bpdu->bridge_id.addr[1];
106 buf[21] = bpdu->bridge_id.addr[2];
107 buf[22] = bpdu->bridge_id.addr[3];
108 buf[23] = bpdu->bridge_id.addr[4];
109 buf[24] = bpdu->bridge_id.addr[5];
110 buf[25] = (bpdu->port_id >> 8) & 0xFF;
111 buf[26] = bpdu->port_id & 0xFF;
113 br_set_ticks(buf+27, bpdu->message_age);
114 br_set_ticks(buf+29, bpdu->max_age);
115 br_set_ticks(buf+31, bpdu->hello_time);
116 br_set_ticks(buf+33, bpdu->forward_delay);
118 br_send_bpdu(p, buf, 35);
121 /* called under bridge lock */
122 void br_send_tcn_bpdu(struct net_bridge_port *p)
124 unsigned char buf[4];
126 if (p->br->stp_enabled != BR_KERNEL_STP)
132 buf[3] = BPDU_TYPE_TCN;
133 br_send_bpdu(p, buf, 4);
139 * NO locks, but rcu_read_lock
141 void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
142 struct net_device *dev)
144 const unsigned char *dest = eth_hdr(skb)->h_dest;
145 struct net_bridge_port *p;
146 struct net_bridge *br;
147 const unsigned char *buf;
149 if (!pskb_may_pull(skb, 4))
152 /* compare of protocol id and version */
154 if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
157 p = br_port_get_check_rcu(dev);
162 spin_lock(&br->lock);
164 if (br->stp_enabled != BR_KERNEL_STP)
167 if (!(br->dev->flags & IFF_UP))
170 if (p->state == BR_STATE_DISABLED)
173 if (!ether_addr_equal(dest, br->group_addr))
176 if (p->flags & BR_BPDU_GUARD) {
177 br_notice(br, "BPDU received on blocked port %u(%s)\n",
178 (unsigned int) p->port_no, p->dev->name);
179 br_stp_disable_port(p);
183 buf = skb_pull(skb, 3);
185 if (buf[0] == BPDU_TYPE_CONFIG) {
186 struct br_config_bpdu bpdu;
188 if (!pskb_may_pull(skb, 32))
192 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
193 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
195 bpdu.root.prio[0] = buf[2];
196 bpdu.root.prio[1] = buf[3];
197 bpdu.root.addr[0] = buf[4];
198 bpdu.root.addr[1] = buf[5];
199 bpdu.root.addr[2] = buf[6];
200 bpdu.root.addr[3] = buf[7];
201 bpdu.root.addr[4] = buf[8];
202 bpdu.root.addr[5] = buf[9];
203 bpdu.root_path_cost =
208 bpdu.bridge_id.prio[0] = buf[14];
209 bpdu.bridge_id.prio[1] = buf[15];
210 bpdu.bridge_id.addr[0] = buf[16];
211 bpdu.bridge_id.addr[1] = buf[17];
212 bpdu.bridge_id.addr[2] = buf[18];
213 bpdu.bridge_id.addr[3] = buf[19];
214 bpdu.bridge_id.addr[4] = buf[20];
215 bpdu.bridge_id.addr[5] = buf[21];
216 bpdu.port_id = (buf[22] << 8) | buf[23];
218 bpdu.message_age = br_get_ticks(buf+24);
219 bpdu.max_age = br_get_ticks(buf+26);
220 bpdu.hello_time = br_get_ticks(buf+28);
221 bpdu.forward_delay = br_get_ticks(buf+30);
223 if (bpdu.message_age > bpdu.max_age) {
226 "port %u config from %pM"
227 " (message_age %ul > max_age %ul)\n",
229 eth_hdr(skb)->h_source,
230 bpdu.message_age, bpdu.max_age);
234 br_received_config_bpdu(p, &bpdu);
235 } else if (buf[0] == BPDU_TYPE_TCN) {
236 br_received_tcn_bpdu(p);
239 spin_unlock(&br->lock);