1
0
mirror of https://github.com/torvalds/linux.git synced 2024-12-03 17:41:22 +00:00
linux/net/bridge/br_stp_bpdu.c
Stephen Hemminger 547b4e7181 bridge: set priority of STP packets
Spanning Tree Protocol packets should have always been marked as
control packets, this causes them to get queued in the high prirority
FIFO. As Radia Perlman mentioned in her LCA talk, STP dies if bridge
gets overloaded and can't communicate. This is a long-standing bug back
to the first versions of Linux bridge.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-02-11 14:16:52 -05:00

242 lines
5.7 KiB
C

/*
* Spanning tree protocol; BPDU handling
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*
* 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 <linux/etherdevice.h>
#include <linux/llc.h>
#include <linux/slab.h>
#include <linux/pkt_sched.h>
#include <net/net_namespace.h>
#include <net/llc.h>
#include <net/llc_pdu.h>
#include <net/stp.h>
#include <asm/unaligned.h>
#include "br_private.h"
#include "br_private_stp.h"
#define STP_HZ 256
#define LLC_RESERVE sizeof(struct llc_pdu_un)
static void br_send_bpdu(struct net_bridge_port *p,
const unsigned char *data, int length)
{
struct sk_buff *skb;
skb = dev_alloc_skb(length+LLC_RESERVE);
if (!skb)
return;
skb->dev = p->dev;
skb->protocol = htons(ETH_P_802_2);
skb->priority = TC_PRIO_CONTROL;
skb_reserve(skb, LLC_RESERVE);
memcpy(__skb_put(skb, length), data, length);
llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
LLC_SAP_BSPAN, LLC_PDU_CMD);
llc_pdu_init_as_ui_cmd(skb);
llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
skb_reset_mac_header(skb);
NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
dev_queue_xmit);
}
static inline void br_set_ticks(unsigned char *dest, int j)
{
unsigned long ticks = (STP_HZ * j)/ HZ;
put_unaligned_be16(ticks, dest);
}
static inline int br_get_ticks(const unsigned char *src)
{
unsigned long ticks = get_unaligned_be16(src);
return DIV_ROUND_UP(ticks * HZ, STP_HZ);
}
/* called under bridge lock */
void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
unsigned char buf[35];
if (p->br->stp_enabled != BR_KERNEL_STP)
return;
buf[0] = 0;
buf[1] = 0;
buf[2] = 0;
buf[3] = BPDU_TYPE_CONFIG;
buf[4] = (bpdu->topology_change ? 0x01 : 0) |
(bpdu->topology_change_ack ? 0x80 : 0);
buf[5] = bpdu->root.prio[0];
buf[6] = bpdu->root.prio[1];
buf[7] = bpdu->root.addr[0];
buf[8] = bpdu->root.addr[1];
buf[9] = bpdu->root.addr[2];
buf[10] = bpdu->root.addr[3];
buf[11] = bpdu->root.addr[4];
buf[12] = bpdu->root.addr[5];
buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
buf[16] = bpdu->root_path_cost & 0xFF;
buf[17] = bpdu->bridge_id.prio[0];
buf[18] = bpdu->bridge_id.prio[1];
buf[19] = bpdu->bridge_id.addr[0];
buf[20] = bpdu->bridge_id.addr[1];
buf[21] = bpdu->bridge_id.addr[2];
buf[22] = bpdu->bridge_id.addr[3];
buf[23] = bpdu->bridge_id.addr[4];
buf[24] = bpdu->bridge_id.addr[5];
buf[25] = (bpdu->port_id >> 8) & 0xFF;
buf[26] = bpdu->port_id & 0xFF;
br_set_ticks(buf+27, bpdu->message_age);
br_set_ticks(buf+29, bpdu->max_age);
br_set_ticks(buf+31, bpdu->hello_time);
br_set_ticks(buf+33, bpdu->forward_delay);
br_send_bpdu(p, buf, 35);
}
/* called under bridge lock */
void br_send_tcn_bpdu(struct net_bridge_port *p)
{
unsigned char buf[4];
if (p->br->stp_enabled != BR_KERNEL_STP)
return;
buf[0] = 0;
buf[1] = 0;
buf[2] = 0;
buf[3] = BPDU_TYPE_TCN;
br_send_bpdu(p, buf, 4);
}
/*
* Called from llc.
*
* NO locks, but rcu_read_lock
*/
void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
struct net_device *dev)
{
const unsigned char *dest = eth_hdr(skb)->h_dest;
struct net_bridge_port *p;
struct net_bridge *br;
const unsigned char *buf;
if (!pskb_may_pull(skb, 4))
goto err;
/* compare of protocol id and version */
buf = skb->data;
if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
goto err;
p = br_port_get_rcu(dev);
if (!p)
goto err;
br = p->br;
spin_lock(&br->lock);
if (br->stp_enabled != BR_KERNEL_STP)
goto out;
if (!(br->dev->flags & IFF_UP))
goto out;
if (p->state == BR_STATE_DISABLED)
goto out;
if (!ether_addr_equal(dest, br->group_addr))
goto out;
if (p->flags & BR_BPDU_GUARD) {
br_notice(br, "BPDU received on blocked port %u(%s)\n",
(unsigned int) p->port_no, p->dev->name);
br_stp_disable_port(p);
goto out;
}
buf = skb_pull(skb, 3);
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);
if (bpdu.message_age > bpdu.max_age) {
if (net_ratelimit())
br_notice(p->br,
"port %u config from %pM"
" (message_age %ul > max_age %ul)\n",
p->port_no,
eth_hdr(skb)->h_source,
bpdu.message_age, bpdu.max_age);
goto out;
}
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);
}