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Commit 42cf93cd authored by Patrick McHardy's avatar Patrick McHardy Committed by David S. Miller
Browse files

[NETFILTER]: Fix bridge netfilter related in xfrm_lookup 



The bridge-netfilter code attaches a fake dst_entry with dst->ops == NULL
to purely bridged packets. When these packets are SNATed and a policy
lookup is done, xfrm_lookup crashes because it tries to dereference
dst->ops.

Change xfrm_lookup not to dereference dst->ops before checking for the
DST_NOXFRM flag and set this flag in the fake dst_entry.

Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a80614d1

net/bridge/br_netfilter.c

+1 −0
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ static struct rtable __fake_rtable = { 
			.dev			= &__fake_net_device,

			.path			= &__fake_rtable.u.dst,

			.metrics		= {[RTAX_MTU - 1] = 1500},

			.flags			= DST_NOXFRM,

		}

	},

	.rt_flags	= 0,

net/xfrm/xfrm_policy.c

+4 −3
Original line number Diff line number Diff line
@@ -782,7 +782,7 @@ int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 
	int nx = 0;

	int err;

	u32 genid;

	u16 family = dst_orig->ops->family;

	u16 family;

	u8 dir = policy_to_flow_dir(XFRM_POLICY_OUT);

	u32 sk_sid = security_sk_sid(sk, fl, dir);

restart:
@@ -796,13 +796,14 @@ int xfrm_lookup(struct dst_entry **dst_p, struct flowi *fl, 
		if ((dst_orig->flags & DST_NOXFRM) || !xfrm_policy_list[XFRM_POLICY_OUT])

			return 0;



		policy = flow_cache_lookup(fl, sk_sid, family, dir,

					   xfrm_policy_lookup);

		policy = flow_cache_lookup(fl, sk_sid, dst_orig->ops->family,

					   dir, xfrm_policy_lookup);

	}



	if (!policy)

		return 0;



	family = dst_orig->ops->family;

	policy->curlft.use_time = (unsigned long)xtime.tv_sec;



	switch (policy->action) {