fda93d92d7
Bridge's communicate with each other using Spanning Tree Protocol over a standard multicast address. There are times when testing or layering bridges over existing topologies or tunnels, when it is useful to use alternative multicast addresses for STP packets. The 802.1d standard has some unused addresses, that can be used for this. This patch is restrictive in that it only allows one of the possible addresses in the standard. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
160 lines
3.7 KiB
C
160 lines
3.7 KiB
C
/*
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* Handle incoming frames
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* Linux ethernet bridge
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*
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* Authors:
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* Lennert Buytenhek <buytenh@gnu.org>
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*
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* $Id: br_input.c,v 1.10 2001/12/24 04:50:20 davem Exp $
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/netfilter_bridge.h>
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#include "br_private.h"
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/* Bridge group multicast address 802.1d (pg 51). */
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const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
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static void br_pass_frame_up(struct net_bridge *br, struct sk_buff *skb)
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{
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struct net_device *indev;
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br->statistics.rx_packets++;
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br->statistics.rx_bytes += skb->len;
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indev = skb->dev;
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skb->dev = br->dev;
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NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
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netif_receive_skb);
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}
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/* note: already called with rcu_read_lock (preempt_disabled) */
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int br_handle_frame_finish(struct sk_buff *skb)
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{
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const unsigned char *dest = eth_hdr(skb)->h_dest;
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struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
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struct net_bridge *br;
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struct net_bridge_fdb_entry *dst;
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int passedup = 0;
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if (!p || p->state == BR_STATE_DISABLED)
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goto drop;
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/* insert into forwarding database after filtering to avoid spoofing */
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br = p->br;
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br_fdb_update(br, p, eth_hdr(skb)->h_source);
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if (p->state == BR_STATE_LEARNING)
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goto drop;
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if (br->dev->flags & IFF_PROMISC) {
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struct sk_buff *skb2;
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skb2 = skb_clone(skb, GFP_ATOMIC);
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if (skb2 != NULL) {
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passedup = 1;
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br_pass_frame_up(br, skb2);
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}
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}
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if (is_multicast_ether_addr(dest)) {
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br_flood_forward(br, skb, !passedup);
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if (!passedup)
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br_pass_frame_up(br, skb);
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goto out;
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}
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dst = __br_fdb_get(br, dest);
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if (dst != NULL && dst->is_local) {
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if (!passedup)
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br_pass_frame_up(br, skb);
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else
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kfree_skb(skb);
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goto out;
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}
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if (dst != NULL) {
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br_forward(dst->dst, skb);
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goto out;
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}
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br_flood_forward(br, skb, 0);
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out:
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return 0;
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drop:
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kfree_skb(skb);
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goto out;
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}
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/* note: already called with rcu_read_lock (preempt_disabled) */
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static int br_handle_local_finish(struct sk_buff *skb)
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{
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struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
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if (p && p->state != BR_STATE_DISABLED)
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br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
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return 0; /* process further */
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}
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/* Does address match the link local multicast address.
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* 01:80:c2:00:00:0X
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*/
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static inline int is_link_local(const const unsigned char *dest)
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{
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return memcmp(dest, br_group_address, 5) == 0 && (dest[5] & 0xf0) == 0;
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}
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/*
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* Called via br_handle_frame_hook.
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* Return 0 if *pskb should be processed furthur
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* 1 if *pskb is handled
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* note: already called with rcu_read_lock (preempt_disabled)
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*/
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int br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb)
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{
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struct sk_buff *skb = *pskb;
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const unsigned char *dest = eth_hdr(skb)->h_dest;
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if (p->state == BR_STATE_DISABLED)
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goto err;
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if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
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goto err;
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if (unlikely(is_link_local(dest))) {
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skb->pkt_type = PACKET_HOST;
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return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
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NULL, br_handle_local_finish) != 0;
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}
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if (p->state == BR_STATE_FORWARDING || p->state == BR_STATE_LEARNING) {
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if (br_should_route_hook) {
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if (br_should_route_hook(pskb))
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return 0;
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skb = *pskb;
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dest = eth_hdr(skb)->h_dest;
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}
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if (!compare_ether_addr(p->br->dev->dev_addr, dest))
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skb->pkt_type = PACKET_HOST;
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NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
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br_handle_frame_finish);
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return 1;
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}
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err:
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kfree_skb(skb);
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return 1;
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}
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