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>
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 139b78b..dced3f6 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -72,7 +72,8 @@
sack_ok : 1,
wscale_ok : 1,
ecn_ok : 1,
- acked : 1;
+ acked : 1,
+ no_srccheck: 1;
struct ip_options *opt;
};
@@ -204,4 +205,9 @@
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 250e6ef..90b27f6 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -140,12 +140,15 @@
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);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d13688e..8b24bd8 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -591,6 +591,7 @@
ip_hdr(skb)->saddr, /* XXX */
sizeof(struct tcphdr), IPPROTO_TCP, 0);
arg.csumoffset = offsetof(struct tcphdr, check) / 2;
+ arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
net = dev_net(skb->dst->dev);
ip_send_reply(net->ipv4.tcp_sock, skb,
@@ -606,7 +607,8 @@
static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
u32 win, u32 ts, int oif,
- struct tcp_md5sig_key *key)
+ struct tcp_md5sig_key *key,
+ int reply_flags)
{
struct tcphdr *th = tcp_hdr(skb);
struct {
@@ -659,6 +661,7 @@
ip_hdr(skb)->daddr, &rep.th);
}
#endif
+ arg.flags = reply_flags;
arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
ip_hdr(skb)->saddr, /* XXX */
arg.iov[0].iov_len, IPPROTO_TCP, 0);
@@ -681,7 +684,8 @@
tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
tcptw->tw_ts_recent,
tw->tw_bound_dev_if,
- tcp_twsk_md5_key(tcptw)
+ tcp_twsk_md5_key(tcptw),
+ tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0
);
inet_twsk_put(tw);
@@ -694,7 +698,8 @@
tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
req->ts_recent,
0,
- tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr));
+ tcp_v4_md5_do_lookup(sk, ip_hdr(skb)->daddr),
+ inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0);
}
/*
@@ -1244,6 +1249,7 @@
ireq = inet_rsk(req);
ireq->loc_addr = daddr;
ireq->rmt_addr = saddr;
+ ireq->no_srccheck = inet_sk(sk)->transparent;
ireq->opt = tcp_v4_save_options(sk, skb);
if (!want_cookie)
TCP_ECN_create_request(req, tcp_hdr(skb));
