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Disable rp_filter for IPsec packets

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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>
This commit is contained in:
Michael Smith 2011-04-07 04:51:51 +00:00 committed by David S. Miller
parent 5c04c819a2
commit 990078afbf
2 changed files with 14 additions and 1 deletions
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9
include/net/xfrm.h
View file

@ -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)
{

6
net/ipv4/fib_frontend.c
View file

@ -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;
}