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/if_ether.h>
  18 #include <linux/if_bridge.h>
  19 #include <linux/netfilter_bridge.h>
  20 #include "br_private.h"
  21 #include "br_private_stp.h"
  22
  23 #define JIFFIES_TO_TICKS(j) (((j) << 8) / HZ)
  24 #define TICKS_TO_JIFFIES(j) (((j) * HZ) >> 8)
  25
  26 static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length)
  27 {
  28         struct net_device *dev;
  29         struct sk_buff *skb;
  30         int size;
  31
  32         if (!p->br->stp_enabled)
  33                 return;
  34
  35         size = length + 2*ETH_ALEN + 2;
  36         if (size < 60)
  37                 size = 60;
  38
  39         dev = p->dev;
  40
  41         if ((skb = dev_alloc_skb(size)) == NULL) {
  42                 printk(KERN_INFO "br: memory squeeze!\n");
  43                 return;
  44         }
  45
  46         skb->dev = dev;
  47         skb->protocol = htons(ETH_P_802_2);
  48         skb->mac.raw = skb_put(skb, size);
  49         memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);
  50         memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);
  51         skb->mac.raw[2*ETH_ALEN] = 0;
  52         skb->mac.raw[2*ETH_ALEN+1] = length;
  53         skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;
  54         memcpy(skb->nh.raw, data, length);
  55         memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);
  56
  57         NF_HOOK(PF_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 jiff)
  62 {
  63         __u16 ticks;
  64
  65         ticks = JIFFIES_TO_TICKS(jiff);
  66         dest[0] = (ticks >> 8) & 0xFF;
  67         dest[1] = ticks & 0xFF;
  68 }
  69
  70 static __inline__ int br_get_ticks(unsigned char *dest)
  71 {
  72         return TICKS_TO_JIFFIES((dest[0] << 8) | dest[1]);
  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[38];
  79
  80         buf[0] = 0x42;
  81         buf[1] = 0x42;
  82         buf[2] = 0x03;
  83         buf[3] = 0;
  84         buf[4] = 0;
  85         buf[5] = 0;
  86         buf[6] = BPDU_TYPE_CONFIG;
  87         buf[7] = (bpdu->topology_change ? 0x01 : 0) |
  88                 (bpdu->topology_change_ack ? 0x80 : 0);
  89         buf[8] = bpdu->root.prio[0];
  90         buf[9] = bpdu->root.prio[1];
  91         buf[10] = bpdu->root.addr[0];
  92         buf[11] = bpdu->root.addr[1];
  93         buf[12] = bpdu->root.addr[2];
  94         buf[13] = bpdu->root.addr[3];
  95         buf[14] = bpdu->root.addr[4];
  96         buf[15] = bpdu->root.addr[5];
  97         buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;
  98         buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;
  99         buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;
 100         buf[19] = bpdu->root_path_cost & 0xFF;
 101         buf[20] = bpdu->bridge_id.prio[0];
 102         buf[21] = bpdu->bridge_id.prio[1];
 103         buf[22] = bpdu->bridge_id.addr[0];
 104         buf[23] = bpdu->bridge_id.addr[1];
 105         buf[24] = bpdu->bridge_id.addr[2];
 106         buf[25] = bpdu->bridge_id.addr[3];
 107         buf[26] = bpdu->bridge_id.addr[4];
 108         buf[27] = bpdu->bridge_id.addr[5];
 109         buf[28] = (bpdu->port_id >> 8) & 0xFF;
 110         buf[29] = bpdu->port_id & 0xFF;
 111
 112         br_set_ticks(buf+30, bpdu->message_age);
 113         br_set_ticks(buf+32, bpdu->max_age);
 114         br_set_ticks(buf+34, bpdu->hello_time);
 115         br_set_ticks(buf+36, bpdu->forward_delay);
 116
 117         br_send_bpdu(p, buf, 38);
 118 }
 119
 120 /* called under bridge lock */
 121 void br_send_tcn_bpdu(struct net_bridge_port *p)
 122 {
 123         unsigned char buf[7];
 124
 125         buf[0] = 0x42;
 126         buf[1] = 0x42;
 127         buf[2] = 0x03;
 128         buf[3] = 0;
 129         buf[4] = 0;
 130         buf[5] = 0;
 131         buf[6] = BPDU_TYPE_TCN;
 132         br_send_bpdu(p, buf, 7);
 133 }
 134
 135 static unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
 136
 137 /* called under bridge lock */
 138 int br_stp_handle_bpdu(struct sk_buff *skb)
 139 {
 140         unsigned char *buf;
 141         struct net_bridge_port *p;
 142
 143         p = skb->dev->br_port;
 144
 145         if (!p->br->stp_enabled ||
 146             !pskb_may_pull(skb, sizeof(header)+1) ||
 147             memcmp(skb->data, header, sizeof(header)))
 148                 goto err;
 149
 150         buf = skb_pull(skb, sizeof(header));
 151         if (buf[0] == BPDU_TYPE_CONFIG) {
 152                 struct br_config_bpdu bpdu;
 153
 154                 if (!pskb_may_pull(skb, 32))
 155                         goto err;
 156
 157                 buf = skb->data;
 158                 bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
 159                 bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
 160
 161                 bpdu.root.prio[0] = buf[2];
 162                 bpdu.root.prio[1] = buf[3];
 163                 bpdu.root.addr[0] = buf[4];
 164                 bpdu.root.addr[1] = buf[5];
 165                 bpdu.root.addr[2] = buf[6];
 166                 bpdu.root.addr[3] = buf[7];
 167                 bpdu.root.addr[4] = buf[8];
 168                 bpdu.root.addr[5] = buf[9];
 169                 bpdu.root_path_cost =
 170                         (buf[10] << 24) |
 171                         (buf[11] << 16) |
 172                         (buf[12] << 8) |
 173                         buf[13];
 174                 bpdu.bridge_id.prio[0] = buf[14];
 175                 bpdu.bridge_id.prio[1] = buf[15];
 176                 bpdu.bridge_id.addr[0] = buf[16];
 177                 bpdu.bridge_id.addr[1] = buf[17];
 178                 bpdu.bridge_id.addr[2] = buf[18];
 179                 bpdu.bridge_id.addr[3] = buf[19];
 180                 bpdu.bridge_id.addr[4] = buf[20];
 181                 bpdu.bridge_id.addr[5] = buf[21];
 182                 bpdu.port_id = (buf[22] << 8) | buf[23];
 183
 184                 bpdu.message_age = br_get_ticks(buf+24);
 185                 bpdu.max_age = br_get_ticks(buf+26);
 186                 bpdu.hello_time = br_get_ticks(buf+28);
 187                 bpdu.forward_delay = br_get_ticks(buf+30);
 188
 189                 br_received_config_bpdu(p, &bpdu);
 190         }
 191
 192         else if (buf[0] == BPDU_TYPE_TCN) {
 193                 br_received_tcn_bpdu(p);
 194         }
 195
 196  err:
 197         kfree_skb(skb);
 198         return 0;
 199 }