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/*
* Spanning tree protocol; BPDU handling
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*
* $Id: br_stp_bpdu.c,v 1.3 2001/11/10 02:35:25 davem Exp $
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/netfilter_bridge.h>
#include "br_private.h"
#include "br_private_stp.h"
#define JIFFIES_TO_TICKS(j) (((j) << 8) / HZ)
#define TICKS_TO_JIFFIES(j) (((j) * HZ) >> 8)
static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length)
{
struct net_device *dev;
struct sk_buff *skb;
int size;
if (!p->br->stp_enabled)
return;
size = length + 2*ETH_ALEN + 2;
if (size < 60)
size = 60;
dev = p->dev;
if ((skb = dev_alloc_skb(size)) == NULL) {
printk(KERN_INFO "br: memory squeeze!\n");
return;
}
skb->dev = dev;
skb->protocol = htons(ETH_P_802_2);
skb->mac.raw = skb_put(skb, size);
memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);
memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);
skb->mac.raw[2*ETH_ALEN] = 0;
skb->mac.raw[2*ETH_ALEN+1] = length;
skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;
memcpy(skb->nh.raw, data, length);
memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);
NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
dev_queue_xmit);
}
static __inline__ void br_set_ticks(unsigned char *dest, int jiff)
{
__u16 ticks;
ticks = JIFFIES_TO_TICKS(jiff);
dest[0] = (ticks >> 8) & 0xFF;
dest[1] = ticks & 0xFF;
}
static __inline__ int br_get_ticks(unsigned char *dest)
{
return TICKS_TO_JIFFIES((dest[0] << 8) | dest[1]);
}
/* called under bridge lock */
void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
unsigned char buf[38];
buf[0] = 0x42;
buf[1] = 0x42;
buf[2] = 0x03;
buf[3] = 0;
buf[4] = 0;
buf[5] = 0;
buf[6] = BPDU_TYPE_CONFIG;
buf[7] = (bpdu->topology_change ? 0x01 : 0) |
(bpdu->topology_change_ack ? 0x80 : 0);
buf[8] = bpdu->root.prio[0];
buf[9] = bpdu->root.prio[1];
buf[10] = bpdu->root.addr[0];
buf[11] = bpdu->root.addr[1];
buf[12] = bpdu->root.addr[2];
buf[13] = bpdu->root.addr[3];
buf[14] = bpdu->root.addr[4];
buf[15] = bpdu->root.addr[5];
buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;
buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;
buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;
buf[19] = bpdu->root_path_cost & 0xFF;
buf[20] = bpdu->bridge_id.prio[0];
buf[21] = bpdu->bridge_id.prio[1];
buf[22] = bpdu->bridge_id.addr[0];
buf[23] = bpdu->bridge_id.addr[1];
buf[24] = bpdu->bridge_id.addr[2];
buf[25] = bpdu->bridge_id.addr[3];
buf[26] = bpdu->bridge_id.addr[4];
buf[27] = bpdu->bridge_id.addr[5];
buf[28] = (bpdu->port_id >> 8) & 0xFF;
buf[29] = bpdu->port_id & 0xFF;
br_set_ticks(buf+30, bpdu->message_age);
br_set_ticks(buf+32, bpdu->max_age);
br_set_ticks(buf+34, bpdu->hello_time);
br_set_ticks(buf+36, bpdu->forward_delay);
br_send_bpdu(p, buf, 38);
}
/* called under bridge lock */
void br_send_tcn_bpdu(struct net_bridge_port *p)
{
unsigned char buf[7];
buf[0] = 0x42;
buf[1] = 0x42;
buf[2] = 0x03;
buf[3] = 0;
buf[4] = 0;
buf[5] = 0;
buf[6] = BPDU_TYPE_TCN;
br_send_bpdu(p, buf, 7);
}
static const unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
/* NO locks, but rcu_read_lock (preempt_disabled) */
int br_stp_handle_bpdu(struct sk_buff *skb)
{
struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
struct net_bridge *br;
unsigned char *buf;
if (!p)
goto err;
br = p->br;
spin_lock(&br->lock);
if (p->state == BR_STATE_DISABLED || !(br->dev->flags & IFF_UP))
goto out;
/* insert into forwarding database after filtering to avoid spoofing */
br_fdb_update(br, p, eth_hdr(skb)->h_source);
if (!br->stp_enabled)
goto out;
/* need at least the 802 and STP headers */
if (!pskb_may_pull(skb, sizeof(header)+1) ||
memcmp(skb->data, header, sizeof(header)))
goto out;
buf = skb_pull(skb, sizeof(header));
if (buf[0] == BPDU_TYPE_CONFIG) {
struct br_config_bpdu bpdu;
if (!pskb_may_pull(skb, 32))
goto out;
buf = skb->data;
bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
bpdu.root.prio[0] = buf[2];
bpdu.root.prio[1] = buf[3];
bpdu.root.addr[0] = buf[4];
bpdu.root.addr[1] = buf[5];
bpdu.root.addr[2] = buf[6];
bpdu.root.addr[3] = buf[7];
bpdu.root.addr[4] = buf[8];
bpdu.root.addr[5] = buf[9];
bpdu.root_path_cost =
(buf[10] << 24) |
(buf[11] << 16) |
(buf[12] << 8) |
buf[13];
bpdu.bridge_id.prio[0] = buf[14];
bpdu.bridge_id.prio[1] = buf[15];
bpdu.bridge_id.addr[0] = buf[16];
bpdu.bridge_id.addr[1] = buf[17];
bpdu.bridge_id.addr[2] = buf[18];
bpdu.bridge_id.addr[3] = buf[19];
bpdu.bridge_id.addr[4] = buf[20];
bpdu.bridge_id.addr[5] = buf[21];
bpdu.port_id = (buf[22] << 8) | buf[23];
bpdu.message_age = br_get_ticks(buf+24);
bpdu.max_age = br_get_ticks(buf+26);
bpdu.hello_time = br_get_ticks(buf+28);
bpdu.forward_delay = br_get_ticks(buf+30);
br_received_config_bpdu(p, &bpdu);
}
else if (buf[0] == BPDU_TYPE_TCN) {
br_received_tcn_bpdu(p);
}
out:
spin_unlock(&br->lock);
err:
kfree_skb(skb);
return 0;
}
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