[NETFILTER]: bridge netfilter: deal with martians correctly (f216f082) · Commits · 戴 / test

net/bridge/br_netfilter.c

+28 −8

Original line number	Diff line number	Diff line
		@@ -34,6 +34,7 @@
		#include <linux/netfilter_ipv6.h>
		#include <linux/netfilter_arp.h>
		#include <linux/in_route.h>
		#include <linux/inetdevice.h>

		#include <net/ip.h>
		#include <net/ipv6.h>
		@@ -221,10 +222,14 @@ static void __br_dnat_complain(void)
		*
		* Otherwise, the packet is considered to be routed and we just
		* change the destination MAC address so that the packet will
		* later be passed up to the IP stack to be routed.
		* later be passed up to the IP stack to be routed. For a redirected
		* packet, ip_route_input() will give back the localhost as output device,
		* which differs from the bridge device.
		*
		* Let us now consider the case that ip_route_input() fails:
		*
		* This can be because the destination address is martian, in which case
		* the packet will be dropped.
		* After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
		* will fail, while __ip_route_output_key() will return success. The source
		* address for __ip_route_output_key() is set to zero, so __ip_route_output_key
		@@ -237,7 +242,8 @@ static void __br_dnat_complain(void)
		*
		* --Lennert, 20020411
		* --Bart, 20020416 (updated)
		* --Bart, 20021007 (updated) */
		* --Bart, 20021007 (updated)
		* --Bart, 20062711 (updated) */
		static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
		{
		if (skb->pkt_type == PACKET_OTHERHOST) {
		@@ -264,15 +270,15 @@ static int br_nf_pre_routing_finish(struct sk_buff *skb)
		struct net_device *dev = skb->dev;
		struct iphdr *iph = skb->nh.iph;
		struct nf_bridge_info *nf_bridge = skb->nf_bridge;
		int err;

		if (nf_bridge->mask & BRNF_PKT_TYPE) {
		skb->pkt_type = PACKET_OTHERHOST;
		nf_bridge->mask ^= BRNF_PKT_TYPE;
		}
		nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;

		if (dnat_took_place(skb)) {
		if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev)) {
		if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
		struct rtable *rt;
		struct flowi fl = {
		.nl_u = {
		@@ -283,19 +289,33 @@ static int br_nf_pre_routing_finish(struct sk_buff *skb)
		},
		.proto = 0,
		};
		struct in_device *in_dev = in_dev_get(dev);

		/* If err equals -EHOSTUNREACH the error is due to a
		* martian destination or due to the fact that
		* forwarding is disabled. For most martian packets,
		* ip_route_output_key() will fail. It won't fail for 2 types of
		* martian destinations: loopback destinations and destination
		* 0.0.0.0. In both cases the packet will be dropped because the
		* destination is the loopback device and not the bridge. */
		if (err != -EHOSTUNREACH \|\| !in_dev \|\| IN_DEV_FORWARD(in_dev))
		goto free_skb;

		if (!ip_route_output_key(&rt, &fl)) {
		/* - Bridged-and-DNAT'ed traffic doesn't
		* require ip_forwarding.
		* - Deal with redirected traffic. */
		if (((struct dst_entry *)rt)->dev == dev \|\|
		rt->rt_type == RTN_LOCAL) {
		* require ip_forwarding. */
		if (((struct dst_entry *)rt)->dev == dev) {
		skb->dst = (struct dst_entry *)rt;
		goto bridged_dnat;
		}
		/* we are sure that forwarding is disabled, so printing
		* this message is no problem. Note that the packet could
		* still have a martian destination address, in which case
		* the packet could be dropped even if forwarding were enabled */
		__br_dnat_complain();
		dst_release((struct dst_entry *)rt);
		}
		free_skb:
		kfree_skb(skb);
		return 0;
		} else {

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