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 void br_send_bpdu(struct net_bridge_port *p, 34 const unsigned char *data, int length) 35 { 36 struct sk_buff *skb; 37 38 skb = dev_alloc_skb(length+LLC_RESERVE); 39 if (!skb) 40 return; 41 42 skb->dev = p->dev; 43 skb->protocol = htons(ETH_P_802_2); 44 skb->priority = TC_PRIO_CONTROL; 45 46 skb_reserve(skb, LLC_RESERVE); 47 memcpy(__skb_put(skb, length), data, length); 48 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); 52 53 llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr); 54 55 skb_reset_mac_header(skb); 56 57 NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, 58 dev_queue_xmit); 59 } 60 61 static inline void br_set_ticks(unsigned char *dest, int j) 62 { 63 unsigned long ticks = (STP_HZ * j)/ HZ; 64 65 put_unaligned_be16(ticks, dest); 66 } 67 68 static inline int br_get_ticks(const unsigned char *src) 69 { 70 unsigned long ticks = get_unaligned_be16(src); 71 72 return DIV_ROUND_UP(ticks * HZ, STP_HZ); 73 } 74 75 /* called under bridge lock */ 76 void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu) 77 { 78 unsigned char buf[35]; 79 80 if (p->br->stp_enabled != BR_KERNEL_STP) 81 return; 82 83 buf[0] = 0; 84 buf[1] = 0; 85 buf[2] = 0; 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; 111 112 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); 116 117 br_send_bpdu(p, buf, 35); 118 } 119 120 /* called under bridge lock */ 121 void br_send_tcn_bpdu(struct net_bridge_port *p) 122 { 123 unsigned char buf[4]; 124 125 if (p->br->stp_enabled != BR_KERNEL_STP) 126 return; 127 128 buf[0] = 0; 129 buf[1] = 0; 130 buf[2] = 0; 131 buf[3] = BPDU_TYPE_TCN; 132 br_send_bpdu(p, buf, 4); 133 } 134 135 /* 136 * Called from llc. 137 * 138 * NO locks, but rcu_read_lock 139 */ 140 void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb, 141 struct net_device *dev) 142 { 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; 147 148 if (!pskb_may_pull(skb, 4)) 149 goto err; 150 151 /* compare of protocol id and version */ 152 buf = skb->data; 153 if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0) 154 goto err; 155 156 p = br_port_get_check_rcu(dev); 157 if (!p) 158 goto err; 159 160 br = p->br; 161 spin_lock(&br->lock); 162 163 if (br->stp_enabled != BR_KERNEL_STP) 164 goto out; 165 166 if (!(br->dev->flags & IFF_UP)) 167 goto out; 168 169 if (p->state == BR_STATE_DISABLED) 170 goto out; 171 172 if (!ether_addr_equal(dest, br->group_addr)) 173 goto out; 174 175 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); 179 goto out; 180 } 181 182 buf = skb_pull(skb, 3); 183 184 if (buf[0] == BPDU_TYPE_CONFIG) { 185 struct br_config_bpdu bpdu; 186 187 if (!pskb_may_pull(skb, 32)) 188 goto out; 189 190 buf = skb->data; 191 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0; 192 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0; 193 194 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 = 203 (buf[10] << 24) | 204 (buf[11] << 16) | 205 (buf[12] << 8) | 206 buf[13]; 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]; 216 217 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); 221 222 if (bpdu.message_age > bpdu.max_age) { 223 if (net_ratelimit()) 224 br_notice(p->br, 225 "port %u config from %pM" 226 " (message_age %ul > max_age %ul)\n", 227 p->port_no, 228 eth_hdr(skb)->h_source, 229 bpdu.message_age, bpdu.max_age); 230 goto out; 231 } 232 233 br_received_config_bpdu(p, &bpdu); 234 } else if (buf[0] == BPDU_TYPE_TCN) { 235 br_received_tcn_bpdu(p); 236 } 237 out: 238 spin_unlock(&br->lock); 239 err: 240 kfree_skb(skb); 241 } 242