netfilter: SYNPROXY target: restrict to INPUT/FORWARD

Fix a crash in synproxy_send_tcp() when using the SYNPROXY target in the
PREROUTING chain caused by missing routing information.

Reported-by: Nicki P. <xastx@gmx.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c
index f13bd91d9a56..a313c3fbeb46 100644
--- a/net/ipv4/netfilter/ipt_SYNPROXY.c
+++ b/net/ipv4/netfilter/ipt_SYNPROXY.c
@@ -423,6 +423,7 @@ static void synproxy_tg4_destroy(const struct xt_tgdtor_param *par)
 static struct xt_target synproxy_tg4_reg __read_mostly = {
         .name           = "SYNPROXY",
         .family         = NFPROTO_IPV4,
+        .hooks          = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD),
         .target         = synproxy_tg4,
         .targetsize     = sizeof(struct xt_synproxy_info),
         .checkentry     = synproxy_tg4_check,