xfrm: Move child route linkage into xfrm_dst.

XFRM bundle child chains look like this:

	xdst1 --> xdst2 --> xdst3 --> path_dst

All of xdstN are xfrm_dst objects and xdst->u.dst.xfrm is non-NULL.
The final child pointer in the chain, here called 'path_dst', is some
other kind of route such as an ipv4 or ipv6 one.

The xfrm output path pops routes, one at a time, via the child
pointer, until we hit one which has a dst->xfrm pointer which
is NULL.

We can easily preserve the above mechanisms with child sitting
only in the xfrm_dst structure.  All children in the chain
before we break out of the xfrm_output() loop have dst->xfrm
non-NULL and are therefore xfrm_dst objects.

Since we break out of the loop when we find dst->xfrm NULL, we
will not try to dereference 'dst' as if it were an xfrm_dst.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/netfilter/xt_policy.c b/net/netfilter/xt_policy.c
index 2b4ab189bba7..5639fb03bdd9 100644
--- a/net/netfilter/xt_policy.c
+++ b/net/netfilter/xt_policy.c
@@ -93,7 +93,8 @@ match_policy_out(const struct sk_buff *skb, const struct xt_policy_info *info,
 	if (dst->xfrm == NULL)
 		return -1;
 
-	for (i = 0; dst && dst->xfrm; dst = dst->child, i++) {
+	for (i = 0; dst && dst->xfrm;
+	     dst = ((struct xfrm_dst *)dst)->child, i++) {
 		pos = strict ? i : 0;
 		if (pos >= info->len)
 			return 0;