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Date: Wed, 01 Oct 2008 07:42:50 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: hidden@....bme.hu
Cc: kaber@...sh.net, netdev@...r.kernel.org,
netfilter-devel@...r.kernel.org
Subject: Re: [net-next PATCH 06/16] Handle TCP SYN+ACK/ACK/RST transparency
From: KOVACS Krisztian <hidden@....bme.hu>
Date: Wed, 01 Oct 2008 16:24:31 +0200
> 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@....bme.hu>
I had to make some modifications to make this build.
I took two include/net/ip.h modifications from patch 7:
1) Adding flags to ip_reply_arg struct
2) definition of IP_REPLY_ARG_NOSRCCHECK
and the result is included below and added to net-next-2.6
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@....bme.hu>
Signed-off-by: David S. Miller <davem@...emloft.net>
---
include/net/inet_sock.h | 8 +++++++-
include/net/ip.h | 3 +++
net/ipv4/tcp_ipv4.c | 12 +++++++++---
3 files changed, 19 insertions(+), 4 deletions(-)
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 @@ 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 250e6ef..90b27f6 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);
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 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
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_reset(struct sock *sk, struct sk_buff *skb)
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 @@ static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
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 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
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 @@ static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
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 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
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));
--
1.5.6.5
--
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