tcp: Handle TCP SYN+ACK/ACK/RST transparency

The TCP stack sends out SYN+ACK/ACK/RST reply packets in response to
incoming packets. The non-local source address check on output bites
us again, as replies for transparently redirected traffic won't have a
chance to leave the node.

This patch selectively sets the FLOWI_FLAG_ANYSRC flag when doing the
route lookup for those replies. Transparent replies are enabled if the
listening socket has the transparent socket flag set.

Signed-off-by: KOVACS Krisztian <hidden@sch.bme.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 10 insertions, 1 deletions

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 139b78b4dfeb..dced3f64f975 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -72,7 +72,8 @@ struct inet_request_sock {
                                 sack_ok    : 1,
                                 wscale_ok  : 1,
                                 ecn_ok     : 1,
-                                acked      : 1;
+                                acked      : 1,
+                                no_srccheck: 1;
         struct ip_options       *opt;
 };
 
@@ -204,4 +205,9 @@ static inline struct request_sock *inet_reqsk_alloc(struct request_sock_ops *ops
         return req;
 }
 
+static inline __u8 inet_sk_flowi_flags(const struct sock *sk)
+{
+        return inet_sk(sk)->transparent ? FLOWI_FLAG_ANYSRC : 0;
+}
+
 #endif  /* _INET_SOCK_H */
diff --git a/include/net/ip.h b/include/net/ip.h
index 250e6ef025a4..90b27f634b76 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -140,12 +140,15 @@ static inline void ip_tr_mc_map(__be32 addr, char *buf)
 
 struct ip_reply_arg {
         struct kvec iov[1];   
+        int         flags;
         __wsum      csum;
         int         csumoffset; /* u16 offset of csum in iov[0].iov_base */
                                 /* -1 if not needed */ 
         int         bound_dev_if;
 }; 
 
+#define IP_REPLY_ARG_NOSRCCHECK 1
+
 void ip_send_reply(struct sock *sk, struct sk_buff *skb, struct ip_reply_arg *arg,
                    unsigned int len);