1 /* 2 * Spanning tree protocol; BPDU handling 3 * Linux ethernet bridge 4 * 5 * Authors: 6 * Lennert Buytenhek <buytenh@gnu.org> 7 * 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. 12 */ 13 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> 21 #include <net/llc.h> 22 #include <net/llc_pdu.h> 23 #include <net/stp.h> 24 #include <asm/unaligned.h> 25 26 #include "br_private.h" 27 #include "br_private_stp.h" 28 29 #define STP_HZ 256 30 31 #define LLC_RESERVE sizeof(struct llc_pdu_un) 32 33 static int br_send_bpdu_finish(struct net *net, struct sock *sk, 34 struct sk_buff *skb) 35 { 36 return dev_queue_xmit(skb); 37 } 38 39 static void br_send_bpdu(struct net_bridge_port *p, 40 const unsigned char *data, int length) 41 { 42 struct sk_buff *skb; 43 44 skb = dev_alloc_skb(length+LLC_RESERVE); 45 if (!skb) 46 return; 47 48 skb->dev = p->dev; 49 skb->protocol = htons(ETH_P_802_2); 50 skb->priority = TC_PRIO_CONTROL; 51 52 skb_reserve(skb, LLC_RESERVE); 53 __skb_put_data(skb, data, length); 54 55 llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN, 56 LLC_SAP_BSPAN, LLC_PDU_CMD); 57 llc_pdu_init_as_ui_cmd(skb); 58 59 llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr); 60 61 skb_reset_mac_header(skb); 62 63 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, 64 dev_net(p->dev), NULL, skb, NULL, skb->dev, 65 br_send_bpdu_finish); 66 } 67 68 static inline void br_set_ticks(unsigned char *dest, int j) 69 { 70 unsigned long ticks = (STP_HZ * j)/ HZ; 71 72 put_unaligned_be16(ticks, dest); 73 } 74 75 static inline int br_get_ticks(const unsigned char *src) 76 { 77 unsigned long ticks = get_unaligned_be16(src); 78 79 return DIV_ROUND_UP(ticks * HZ, STP_HZ); 80 } 81 82 /* called under bridge lock */ 83 void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu) 84 { 85 unsigned char buf[35]; 86 87 if (p->br->stp_enabled != BR_KERNEL_STP) 88 return; 89 90 buf[0] = 0; 91 buf[1] = 0; 92 buf[2] = 0; 93 buf[3] = BPDU_TYPE_CONFIG; 94 buf[4] = (bpdu->topology_change ? 0x01 : 0) | 95 (bpdu->topology_change_ack ? 0x80 : 0); 96 buf[5] = bpdu->root.prio[0]; 97 buf[6] = bpdu->root.prio[1]; 98 buf[7] = bpdu->root.addr[0]; 99 buf[8] = bpdu->root.addr[1]; 100 buf[9] = bpdu->root.addr[2]; 101 buf[10] = bpdu->root.addr[3]; 102 buf[11] = bpdu->root.addr[4]; 103 buf[12] = bpdu->root.addr[5]; 104 buf[13] = (bpdu->root_path_cost >> 24) & 0xFF; 105 buf[14] = (bpdu->root_path_cost >> 16) & 0xFF; 106 buf[15] = (bpdu->root_path_cost >> 8) & 0xFF; 107 buf[16] = bpdu->root_path_cost & 0xFF; 108 buf[17] = bpdu->bridge_id.prio[0]; 109 buf[18] = bpdu->bridge_id.prio[1]; 110 buf[19] = bpdu->bridge_id.addr[0]; 111 buf[20] = bpdu->bridge_id.addr[1]; 112 buf[21] = bpdu->bridge_id.addr[2]; 113 buf[22] = bpdu->bridge_id.addr[3]; 114 buf[23] = bpdu->bridge_id.addr[4]; 115 buf[24] = bpdu->bridge_id.addr[5]; 116 buf[25] = (bpdu->port_id >> 8) & 0xFF; 117 buf[26] = bpdu->port_id & 0xFF; 118 119 br_set_ticks(buf+27, bpdu->message_age); 120 br_set_ticks(buf+29, bpdu->max_age); 121 br_set_ticks(buf+31, bpdu->hello_time); 122 br_set_ticks(buf+33, bpdu->forward_delay); 123 124 br_send_bpdu(p, buf, 35); 125 } 126 127 /* called under bridge lock */ 128 void br_send_tcn_bpdu(struct net_bridge_port *p) 129 { 130 unsigned char buf[4]; 131 132 if (p->br->stp_enabled != BR_KERNEL_STP) 133 return; 134 135 buf[0] = 0; 136 buf[1] = 0; 137 buf[2] = 0; 138 buf[3] = BPDU_TYPE_TCN; 139 br_send_bpdu(p, buf, 4); 140 } 141 142 /* 143 * Called from llc. 144 * 145 * NO locks, but rcu_read_lock 146 */ 147 void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb, 148 struct net_device *dev) 149 { 150 const unsigned char *dest = eth_hdr(skb)->h_dest; 151 struct net_bridge_port *p; 152 struct net_bridge *br; 153 const unsigned char *buf; 154 155 if (!pskb_may_pull(skb, 4)) 156 goto err; 157 158 /* compare of protocol id and version */ 159 buf = skb->data; 160 if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0) 161 goto err; 162 163 p = br_port_get_check_rcu(dev); 164 if (!p) 165 goto err; 166 167 br = p->br; 168 spin_lock(&br->lock); 169 170 if (br->stp_enabled != BR_KERNEL_STP) 171 goto out; 172 173 if (!(br->dev->flags & IFF_UP)) 174 goto out; 175 176 if (p->state == BR_STATE_DISABLED) 177 goto out; 178 179 if (!ether_addr_equal(dest, br->group_addr)) 180 goto out; 181 182 if (p->flags & BR_BPDU_GUARD) { 183 br_notice(br, "BPDU received on blocked port %u(%s)\n", 184 (unsigned int) p->port_no, p->dev->name); 185 br_stp_disable_port(p); 186 goto out; 187 } 188 189 buf = skb_pull(skb, 3); 190 191 if (buf[0] == BPDU_TYPE_CONFIG) { 192 struct br_config_bpdu bpdu; 193 194 if (!pskb_may_pull(skb, 32)) 195 goto out; 196 197 buf = skb->data; 198 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0; 199 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0; 200 201 bpdu.root.prio[0] = buf[2]; 202 bpdu.root.prio[1] = buf[3]; 203 bpdu.root.addr[0] = buf[4]; 204 bpdu.root.addr[1] = buf[5]; 205 bpdu.root.addr[2] = buf[6]; 206 bpdu.root.addr[3] = buf[7]; 207 bpdu.root.addr[4] = buf[8]; 208 bpdu.root.addr[5] = buf[9]; 209 bpdu.root_path_cost = 210 (buf[10] << 24) | 211 (buf[11] << 16) | 212 (buf[12] << 8) | 213 buf[13]; 214 bpdu.bridge_id.prio[0] = buf[14]; 215 bpdu.bridge_id.prio[1] = buf[15]; 216 bpdu.bridge_id.addr[0] = buf[16]; 217 bpdu.bridge_id.addr[1] = buf[17]; 218 bpdu.bridge_id.addr[2] = buf[18]; 219 bpdu.bridge_id.addr[3] = buf[19]; 220 bpdu.bridge_id.addr[4] = buf[20]; 221 bpdu.bridge_id.addr[5] = buf[21]; 222 bpdu.port_id = (buf[22] << 8) | buf[23]; 223 224 bpdu.message_age = br_get_ticks(buf+24); 225 bpdu.max_age = br_get_ticks(buf+26); 226 bpdu.hello_time = br_get_ticks(buf+28); 227 bpdu.forward_delay = br_get_ticks(buf+30); 228 229 if (bpdu.message_age > bpdu.max_age) { 230 if (net_ratelimit()) 231 br_notice(p->br, 232 "port %u config from %pM" 233 " (message_age %ul > max_age %ul)\n", 234 p->port_no, 235 eth_hdr(skb)->h_source, 236 bpdu.message_age, bpdu.max_age); 237 goto out; 238 } 239 240 br_received_config_bpdu(p, &bpdu); 241 } else if (buf[0] == BPDU_TYPE_TCN) { 242 br_received_tcn_bpdu(p); 243 } 244 out: 245 spin_unlock(&br->lock); 246 err: 247 kfree_skb(skb); 248 } 249