Disable rp_filter for IPsec packets (990078af) · Commits · 戴 / test

The reverse path filter interferes with IPsec subnet-to-subnet tunnels, especially when the link to the IPsec peer is on an interface other than the one hosting the default route. With dynamic routing, where the peer might be reachable through eth0 today and eth1 tomorrow, it's difficult to keep rp_filter enabled unless fake routes to the remote subnets are configured on the interface currently used to reach the peer. IPsec provides a much stronger anti-spoofing policy than rp_filter, so this patch disables the rp_filter for packets with a security path. Signed-off-by:

Michael Smith <msmith@cbnco.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/net/xfrm.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -957,6 +957,15 @@ struct sec_path {
		struct xfrm_state *xvec[XFRM_MAX_DEPTH];
		};

		static inline int secpath_exists(struct sk_buff *skb)
		{
		#ifdef CONFIG_XFRM
		return skb->sp != NULL;
		#else
		return 0;
		#endif
		}

		static inline struct sec_path *
		secpath_get(struct sec_path *sp)
		{

net/ipv4/fib_frontend.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -44,6 +44,7 @@
		#include <net/arp.h>
		#include <net/ip_fib.h>
		#include <net/rtnetlink.h>
		#include <net/xfrm.h>

		#ifndef CONFIG_IP_MULTIPLE_TABLES

		@@ -211,7 +212,10 @@ int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, u8 tos,
		in_dev = __in_dev_get_rcu(dev);
		if (in_dev) {
		no_addr = in_dev->ifa_list == NULL;
		rpf = IN_DEV_RPFILTER(in_dev);

		/* Ignore rp_filter for packets protected by IPsec. */
		rpf = secpath_exists(skb) ? 0 : IN_DEV_RPFILTER(in_dev);

		accept_local = IN_DEV_ACCEPT_LOCAL(in_dev);
		fl4.flowi4_mark = IN_DEV_SRC_VMARK(in_dev) ? skb->mark : 0;
		}

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