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 #include <linux/etherdevice.h> 19 #include <linux/llc.h> 20 #include <net/llc.h> 21 #include <net/llc_pdu.h> 22 #include <asm/unaligned.h> 23 24 #include "br_private.h" 25 #include "br_private_stp.h" 26 27 #define STP_HZ 256 28 29 #define LLC_RESERVE sizeof(struct llc_pdu_un) 30 31 static void br_send_bpdu(struct net_bridge_port *p, 32 const unsigned char *data, int length) 33 { 34 struct sk_buff *skb; 35 36 skb = dev_alloc_skb(length+LLC_RESERVE); 37 if (!skb) 38 return; 39 40 skb->dev = p->dev; 41 skb->protocol = htons(ETH_P_802_2); 42 43 skb_reserve(skb, LLC_RESERVE); 44 memcpy(__skb_put(skb, length), data, length); 45 46 llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN, 47 LLC_SAP_BSPAN, LLC_PDU_CMD); 48 llc_pdu_init_as_ui_cmd(skb); 49 50 llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr); 51 52 NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev, 53 dev_queue_xmit); 54 } 55 56 static inline void br_set_ticks(unsigned char *dest, int j) 57 { 58 unsigned long ticks = (STP_HZ * j)/ HZ; 59 60 put_unaligned(htons(ticks), (__be16 *)dest); 61 } 62 63 static inline int br_get_ticks(const unsigned char *src) 64 { 65 unsigned long ticks = ntohs(get_unaligned((__be16 *)src)); 66 67 return (ticks * HZ + STP_HZ - 1) / STP_HZ; 68 } 69 70 /* called under bridge lock */ 71 void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu) 72 { 73 unsigned char buf[35]; 74 75 if (p->br->stp_enabled != BR_KERNEL_STP) 76 return; 77 78 buf[0] = 0; 79 buf[1] = 0; 80 buf[2] = 0; 81 buf[3] = BPDU_TYPE_CONFIG; 82 buf[4] = (bpdu->topology_change ? 0x01 : 0) | 83 (bpdu->topology_change_ack ? 0x80 : 0); 84 buf[5] = bpdu->root.prio[0]; 85 buf[6] = bpdu->root.prio[1]; 86 buf[7] = bpdu->root.addr[0]; 87 buf[8] = bpdu->root.addr[1]; 88 buf[9] = bpdu->root.addr[2]; 89 buf[10] = bpdu->root.addr[3]; 90 buf[11] = bpdu->root.addr[4]; 91 buf[12] = bpdu->root.addr[5]; 92 buf[13] = (bpdu->root_path_cost >> 24) & 0xFF; 93 buf[14] = (bpdu->root_path_cost >> 16) & 0xFF; 94 buf[15] = (bpdu->root_path_cost >> 8) & 0xFF; 95 buf[16] = bpdu->root_path_cost & 0xFF; 96 buf[17] = bpdu->bridge_id.prio[0]; 97 buf[18] = bpdu->bridge_id.prio[1]; 98 buf[19] = bpdu->bridge_id.addr[0]; 99 buf[20] = bpdu->bridge_id.addr[1]; 100 buf[21] = bpdu->bridge_id.addr[2]; 101 buf[22] = bpdu->bridge_id.addr[3]; 102 buf[23] = bpdu->bridge_id.addr[4]; 103 buf[24] = bpdu->bridge_id.addr[5]; 104 buf[25] = (bpdu->port_id >> 8) & 0xFF; 105 buf[26] = bpdu->port_id & 0xFF; 106 107 br_set_ticks(buf+27, bpdu->message_age); 108 br_set_ticks(buf+29, bpdu->max_age); 109 br_set_ticks(buf+31, bpdu->hello_time); 110 br_set_ticks(buf+33, bpdu->forward_delay); 111 112 br_send_bpdu(p, buf, 35); 113 } 114 115 /* called under bridge lock */ 116 void br_send_tcn_bpdu(struct net_bridge_port *p) 117 { 118 unsigned char buf[4]; 119 120 if (p->br->stp_enabled != BR_KERNEL_STP) 121 return; 122 123 buf[0] = 0; 124 buf[1] = 0; 125 buf[2] = 0; 126 buf[3] = BPDU_TYPE_TCN; 127 br_send_bpdu(p, buf, 4); 128 } 129 130 /* 131 * Called from llc. 132 * 133 * NO locks, but rcu_read_lock (preempt_disabled) 134 */ 135 int br_stp_rcv(struct sk_buff *skb, struct net_device *dev, 136 struct packet_type *pt, struct net_device *orig_dev) 137 { 138 const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb); 139 const unsigned char *dest = eth_hdr(skb)->h_dest; 140 struct net_bridge_port *p = rcu_dereference(dev->br_port); 141 struct net_bridge *br; 142 const unsigned char *buf; 143 144 if (!p) 145 goto err; 146 147 if (pdu->ssap != LLC_SAP_BSPAN 148 || pdu->dsap != LLC_SAP_BSPAN 149 || pdu->ctrl_1 != LLC_PDU_TYPE_U) 150 goto err; 151 152 if (!pskb_may_pull(skb, 4)) 153 goto err; 154 155 /* compare of protocol id and version */ 156 buf = skb->data; 157 if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0) 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 (compare_ether_addr(dest, br->group_addr) != 0) 173 goto out; 174 175 buf = skb_pull(skb, 3); 176 177 if (buf[0] == BPDU_TYPE_CONFIG) { 178 struct br_config_bpdu bpdu; 179 180 if (!pskb_may_pull(skb, 32)) 181 goto out; 182 183 buf = skb->data; 184 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0; 185 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0; 186 187 bpdu.root.prio[0] = buf[2]; 188 bpdu.root.prio[1] = buf[3]; 189 bpdu.root.addr[0] = buf[4]; 190 bpdu.root.addr[1] = buf[5]; 191 bpdu.root.addr[2] = buf[6]; 192 bpdu.root.addr[3] = buf[7]; 193 bpdu.root.addr[4] = buf[8]; 194 bpdu.root.addr[5] = buf[9]; 195 bpdu.root_path_cost = 196 (buf[10] << 24) | 197 (buf[11] << 16) | 198 (buf[12] << 8) | 199 buf[13]; 200 bpdu.bridge_id.prio[0] = buf[14]; 201 bpdu.bridge_id.prio[1] = buf[15]; 202 bpdu.bridge_id.addr[0] = buf[16]; 203 bpdu.bridge_id.addr[1] = buf[17]; 204 bpdu.bridge_id.addr[2] = buf[18]; 205 bpdu.bridge_id.addr[3] = buf[19]; 206 bpdu.bridge_id.addr[4] = buf[20]; 207 bpdu.bridge_id.addr[5] = buf[21]; 208 bpdu.port_id = (buf[22] << 8) | buf[23]; 209 210 bpdu.message_age = br_get_ticks(buf+24); 211 bpdu.max_age = br_get_ticks(buf+26); 212 bpdu.hello_time = br_get_ticks(buf+28); 213 bpdu.forward_delay = br_get_ticks(buf+30); 214 215 br_received_config_bpdu(p, &bpdu); 216 } 217 218 else if (buf[0] == BPDU_TYPE_TCN) { 219 br_received_tcn_bpdu(p); 220 } 221 out: 222 spin_unlock(&br->lock); 223 err: 224 kfree_skb(skb); 225 return 0; 226 } 227