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