1 /* 2 * Spanning tree protocol; BPDU handling 3 * Linux ethernet bridge 4 * 5 * Authors: 6 * Lennert Buytenhek <buytenh@gnu.org> 7 * 8 * $Id: br_stp_bpdu.c,v 1.3 2001/11/10 02:35:25 davem Exp $ 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License 12 * as published by the Free Software Foundation; either version 13 * 2 of the License, or (at your option) any later version. 14 */ 15 16 #include <linux/kernel.h> 17 #include <linux/netfilter_bridge.h> 18 19 #include "br_private.h" 20 #include "br_private_stp.h" 21 22 #define JIFFIES_TO_TICKS(j) (((j) << 8) / HZ) 23 #define TICKS_TO_JIFFIES(j) (((j) * HZ) >> 8) 24 25 static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length) 26 { 27 struct net_device *dev; 28 struct sk_buff *skb; 29 int size; 30 31 if (!p->br->stp_enabled) 32 return; 33 34 size = length + 2*ETH_ALEN + 2; 35 if (size < 60) 36 size = 60; 37 38 dev = p->dev; 39 40 if ((skb = dev_alloc_skb(size)) == NULL) { 41 printk(KERN_INFO "br: memory squeeze!\n"); 42 return; 43 } 44 45 skb->dev = dev; 46 skb->protocol = htons(ETH_P_802_2); 47 skb->mac.raw = skb_put(skb, size); 48 memcpy(skb->mac.raw, bridge_ula, ETH_ALEN); 49 memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN); 50 skb->mac.raw[2*ETH_ALEN] = 0; 51 skb->mac.raw[2*ETH_ALEN+1] = length; 52 skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2; 53 memcpy(skb->nh.raw, data, length); 54 memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2); 55 56 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, 57 dev_queue_xmit); 58 } 59 60 static __inline__ void br_set_ticks(unsigned char *dest, int jiff) 61 { 62 __u16 ticks; 63 64 ticks = JIFFIES_TO_TICKS(jiff); 65 dest[0] = (ticks >> 8) & 0xFF; 66 dest[1] = ticks & 0xFF; 67 } 68 69 static __inline__ int br_get_ticks(unsigned char *dest) 70 { 71 return TICKS_TO_JIFFIES((dest[0] << 8) | dest[1]); 72 } 73 74 /* called under bridge lock */ 75 void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu) 76 { 77 unsigned char buf[38]; 78 79 buf[0] = 0x42; 80 buf[1] = 0x42; 81 buf[2] = 0x03; 82 buf[3] = 0; 83 buf[4] = 0; 84 buf[5] = 0; 85 buf[6] = BPDU_TYPE_CONFIG; 86 buf[7] = (bpdu->topology_change ? 0x01 : 0) | 87 (bpdu->topology_change_ack ? 0x80 : 0); 88 buf[8] = bpdu->root.prio[0]; 89 buf[9] = bpdu->root.prio[1]; 90 buf[10] = bpdu->root.addr[0]; 91 buf[11] = bpdu->root.addr[1]; 92 buf[12] = bpdu->root.addr[2]; 93 buf[13] = bpdu->root.addr[3]; 94 buf[14] = bpdu->root.addr[4]; 95 buf[15] = bpdu->root.addr[5]; 96 buf[16] = (bpdu->root_path_cost >> 24) & 0xFF; 97 buf[17] = (bpdu->root_path_cost >> 16) & 0xFF; 98 buf[18] = (bpdu->root_path_cost >> 8) & 0xFF; 99 buf[19] = bpdu->root_path_cost & 0xFF; 100 buf[20] = bpdu->bridge_id.prio[0]; 101 buf[21] = bpdu->bridge_id.prio[1]; 102 buf[22] = bpdu->bridge_id.addr[0]; 103 buf[23] = bpdu->bridge_id.addr[1]; 104 buf[24] = bpdu->bridge_id.addr[2]; 105 buf[25] = bpdu->bridge_id.addr[3]; 106 buf[26] = bpdu->bridge_id.addr[4]; 107 buf[27] = bpdu->bridge_id.addr[5]; 108 buf[28] = (bpdu->port_id >> 8) & 0xFF; 109 buf[29] = bpdu->port_id & 0xFF; 110 111 br_set_ticks(buf+30, bpdu->message_age); 112 br_set_ticks(buf+32, bpdu->max_age); 113 br_set_ticks(buf+34, bpdu->hello_time); 114 br_set_ticks(buf+36, bpdu->forward_delay); 115 116 br_send_bpdu(p, buf, 38); 117 } 118 119 /* called under bridge lock */ 120 void br_send_tcn_bpdu(struct net_bridge_port *p) 121 { 122 unsigned char buf[7]; 123 124 buf[0] = 0x42; 125 buf[1] = 0x42; 126 buf[2] = 0x03; 127 buf[3] = 0; 128 buf[4] = 0; 129 buf[5] = 0; 130 buf[6] = BPDU_TYPE_TCN; 131 br_send_bpdu(p, buf, 7); 132 } 133 134 static const unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00}; 135 136 /* NO locks */ 137 int br_stp_handle_bpdu(struct sk_buff *skb) 138 { 139 struct net_bridge_port *p = skb->dev->br_port; 140 struct net_bridge *br = p->br; 141 unsigned char *buf; 142 143 /* insert into forwarding database after filtering to avoid spoofing */ 144 br_fdb_update(p->br, p, eth_hdr(skb)->h_source); 145 146 /* need at least the 802 and STP headers */ 147 if (!pskb_may_pull(skb, sizeof(header)+1) || 148 memcmp(skb->data, header, sizeof(header))) 149 goto err; 150 151 buf = skb_pull(skb, sizeof(header)); 152 153 spin_lock_bh(&br->lock); 154 if (p->state == BR_STATE_DISABLED 155 || !(br->dev->flags & IFF_UP) 156 || !br->stp_enabled) 157 goto out; 158 159 if (buf[0] == BPDU_TYPE_CONFIG) { 160 struct br_config_bpdu bpdu; 161 162 if (!pskb_may_pull(skb, 32)) 163 goto out; 164 165 buf = skb->data; 166 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0; 167 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0; 168 169 bpdu.root.prio[0] = buf[2]; 170 bpdu.root.prio[1] = buf[3]; 171 bpdu.root.addr[0] = buf[4]; 172 bpdu.root.addr[1] = buf[5]; 173 bpdu.root.addr[2] = buf[6]; 174 bpdu.root.addr[3] = buf[7]; 175 bpdu.root.addr[4] = buf[8]; 176 bpdu.root.addr[5] = buf[9]; 177 bpdu.root_path_cost = 178 (buf[10] << 24) | 179 (buf[11] << 16) | 180 (buf[12] << 8) | 181 buf[13]; 182 bpdu.bridge_id.prio[0] = buf[14]; 183 bpdu.bridge_id.prio[1] = buf[15]; 184 bpdu.bridge_id.addr[0] = buf[16]; 185 bpdu.bridge_id.addr[1] = buf[17]; 186 bpdu.bridge_id.addr[2] = buf[18]; 187 bpdu.bridge_id.addr[3] = buf[19]; 188 bpdu.bridge_id.addr[4] = buf[20]; 189 bpdu.bridge_id.addr[5] = buf[21]; 190 bpdu.port_id = (buf[22] << 8) | buf[23]; 191 192 bpdu.message_age = br_get_ticks(buf+24); 193 bpdu.max_age = br_get_ticks(buf+26); 194 bpdu.hello_time = br_get_ticks(buf+28); 195 bpdu.forward_delay = br_get_ticks(buf+30); 196 197 br_received_config_bpdu(p, &bpdu); 198 } 199 200 else if (buf[0] == BPDU_TYPE_TCN) { 201 br_received_tcn_bpdu(p); 202 } 203 out: 204 spin_unlock_bh(&br->lock); 205 err: 206 kfree_skb(skb); 207 return 0; 208 } 209