85967bb46d
Avoid poisoning of the bridge forwarding table by frames that have been dropped by filtering. This prevents spoofed source addresses on hostile side of bridge from causing packet leakage, a small but possible security risk. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
146 lines
3.2 KiB
C
146 lines
3.2 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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const unsigned char bridge_ula[6] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
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static int br_pass_frame_up_finish(struct sk_buff *skb)
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{
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#ifdef CONFIG_NETFILTER_DEBUG
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skb->nf_debug = 0;
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#endif
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netif_rx(skb);
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return 0;
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}
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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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br_pass_frame_up_finish);
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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 = skb->dev->br_port;
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struct net_bridge *br = p->br;
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struct net_bridge_fdb_entry *dst;
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int passedup = 0;
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/* insert into forwarding database after filtering to avoid spoofing */
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br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
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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 (dest[0] & 1) {
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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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}
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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 (p->state == BR_STATE_LEARNING)
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br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
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if (p->br->stp_enabled &&
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!memcmp(dest, bridge_ula, 5) &&
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!(dest[5] & 0xF0)) {
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if (!dest[5]) {
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NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
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NULL, br_stp_handle_bpdu);
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return 1;
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}
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}
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else if (p->state == BR_STATE_FORWARDING) {
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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 (!memcmp(p->br->dev->dev_addr, dest, ETH_ALEN))
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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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