git.oblomov.eu Git - linux-2.6/blob - net/bridge/br_stp_bpdu.c

   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 STP_HZ          256
  23
  24 static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length)
  25 {
  26         struct net_device *dev;
  27         struct sk_buff *skb;
  28         int size;
  29
  30         if (!p->br->stp_enabled)
  31                 return;
  32
  33         size = length + 2*ETH_ALEN + 2;
  34         if (size < 60)
  35                 size = 60;
  36
  37         dev = p->dev;
  38
  39         if ((skb = dev_alloc_skb(size)) == NULL) {
  40                 printk(KERN_INFO "br: memory squeeze!\n");
  41                 return;
  42         }
  43
  44         skb->dev = dev;
  45         skb->protocol = htons(ETH_P_802_2);
  46         skb->mac.raw = skb_put(skb, size);
  47         memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);
  48         memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);
  49         skb->mac.raw[2*ETH_ALEN] = 0;
  50         skb->mac.raw[2*ETH_ALEN+1] = length;
  51         skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;
  52         memcpy(skb->nh.raw, data, length);
  53         memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);
  54
  55         NF_HOOK(PF_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         *((__be16 *) dest) = htons(ticks);
  64 }
  65
  66 static inline int br_get_ticks(const unsigned char *src)
  67 {
  68         unsigned long ticks = ntohs(*(__be16 *)src);
  69
  70         return (ticks * HZ + STP_HZ - 1) / 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[38];
  77
  78         buf[0] = 0x42;
  79         buf[1] = 0x42;
  80         buf[2] = 0x03;
  81         buf[3] = 0;
  82         buf[4] = 0;
  83         buf[5] = 0;
  84         buf[6] = BPDU_TYPE_CONFIG;
  85         buf[7] = (bpdu->topology_change ? 0x01 : 0) |
  86                 (bpdu->topology_change_ack ? 0x80 : 0);
  87         buf[8] = bpdu->root.prio[0];
  88         buf[9] = bpdu->root.prio[1];
  89         buf[10] = bpdu->root.addr[0];
  90         buf[11] = bpdu->root.addr[1];
  91         buf[12] = bpdu->root.addr[2];
  92         buf[13] = bpdu->root.addr[3];
  93         buf[14] = bpdu->root.addr[4];
  94         buf[15] = bpdu->root.addr[5];
  95         buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;
  96         buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;
  97         buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;
  98         buf[19] = bpdu->root_path_cost & 0xFF;
  99         buf[20] = bpdu->bridge_id.prio[0];
 100         buf[21] = bpdu->bridge_id.prio[1];
 101         buf[22] = bpdu->bridge_id.addr[0];
 102         buf[23] = bpdu->bridge_id.addr[1];
 103         buf[24] = bpdu->bridge_id.addr[2];
 104         buf[25] = bpdu->bridge_id.addr[3];
 105         buf[26] = bpdu->bridge_id.addr[4];
 106         buf[27] = bpdu->bridge_id.addr[5];
 107         buf[28] = (bpdu->port_id >> 8) & 0xFF;
 108         buf[29] = bpdu->port_id & 0xFF;
 109
 110         br_set_ticks(buf+30, bpdu->message_age);
 111         br_set_ticks(buf+32, bpdu->max_age);
 112         br_set_ticks(buf+34, bpdu->hello_time);
 113         br_set_ticks(buf+36, bpdu->forward_delay);
 114
 115         br_send_bpdu(p, buf, 38);
 116 }
 117
 118 /* called under bridge lock */
 119 void br_send_tcn_bpdu(struct net_bridge_port *p)
 120 {
 121         unsigned char buf[7];
 122
 123         buf[0] = 0x42;
 124         buf[1] = 0x42;
 125         buf[2] = 0x03;
 126         buf[3] = 0;
 127         buf[4] = 0;
 128         buf[5] = 0;
 129         buf[6] = BPDU_TYPE_TCN;
 130         br_send_bpdu(p, buf, 7);
 131 }
 132
 133 static const unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
 134
 135 /* NO locks, but rcu_read_lock (preempt_disabled)  */
 136 int br_stp_handle_bpdu(struct sk_buff *skb)
 137 {
 138         struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
 139         struct net_bridge *br;
 140         unsigned char *buf;
 141
 142         if (!p)
 143                 goto err;
 144
 145         br = p->br;
 146         spin_lock(&br->lock);
 147
 148         if (p->state == BR_STATE_DISABLED || !(br->dev->flags & IFF_UP))
 149                 goto out;
 150
 151         /* insert into forwarding database after filtering to avoid spoofing */
 152         br_fdb_update(br, p, eth_hdr(skb)->h_source);
 153
 154         if (!br->stp_enabled)
 155                 goto out;
 156
 157         /* need at least the 802 and STP headers */
 158         if (!pskb_may_pull(skb, sizeof(header)+1) ||
 159             memcmp(skb->data, header, sizeof(header)))
 160                 goto out;
 161
 162         buf = skb_pull(skb, sizeof(header));
 163
 164         if (buf[0] == BPDU_TYPE_CONFIG) {
 165                 struct br_config_bpdu bpdu;
 166
 167                 if (!pskb_may_pull(skb, 32))
 168                     goto out;
 169
 170                 buf = skb->data;
 171                 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
 172                 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
 173
 174                 bpdu.root.prio[0] = buf[2];
 175                 bpdu.root.prio[1] = buf[3];
 176                 bpdu.root.addr[0] = buf[4];
 177                 bpdu.root.addr[1] = buf[5];
 178                 bpdu.root.addr[2] = buf[6];
 179                 bpdu.root.addr[3] = buf[7];
 180                 bpdu.root.addr[4] = buf[8];
 181                 bpdu.root.addr[5] = buf[9];
 182                 bpdu.root_path_cost =
 183                         (buf[10] << 24) |
 184                         (buf[11] << 16) |
 185                         (buf[12] << 8) |
 186                         buf[13];
 187                 bpdu.bridge_id.prio[0] = buf[14];
 188                 bpdu.bridge_id.prio[1] = buf[15];
 189                 bpdu.bridge_id.addr[0] = buf[16];
 190                 bpdu.bridge_id.addr[1] = buf[17];
 191                 bpdu.bridge_id.addr[2] = buf[18];
 192                 bpdu.bridge_id.addr[3] = buf[19];
 193                 bpdu.bridge_id.addr[4] = buf[20];
 194                 bpdu.bridge_id.addr[5] = buf[21];
 195                 bpdu.port_id = (buf[22] << 8) | buf[23];
 196
 197                 bpdu.message_age = br_get_ticks(buf+24);
 198                 bpdu.max_age = br_get_ticks(buf+26);
 199                 bpdu.hello_time = br_get_ticks(buf+28);
 200                 bpdu.forward_delay = br_get_ticks(buf+30);
 201
 202                 br_received_config_bpdu(p, &bpdu);
 203         }
 204
 205         else if (buf[0] == BPDU_TYPE_TCN) {
 206                 br_received_tcn_bpdu(p);
 207         }
 208  out:
 209         spin_unlock(&br->lock);
 210  err:
 211         kfree_skb(skb);
 212         return 0;
 213 }