[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: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index 6bb0c7eb1ef0300d827d755be0d4eab7f73d600a..e060aad8624d46e9600fd22bee5f27b71920fd4e 100644 (file)
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -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,

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 5e6b05ac126088386dc21a0f15c7543ff2d266b7..8206025d8e46297c786e58fc19fd1725c0bd5ff5 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -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 @@ restart:
                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) {