Current TCP code relies on the local port of the listening socket
being the same as the destination address of the incoming
connection. Port redirection used by many transparent proxying
techniques obviously breaks this, so we have to store the original
destination port address.
This patch extends struct inet_request_sock and stores the incoming
destination port value there. It also modifies the handshake code to
use that value as the source port when sending reply packets.
Signed-off-by: KOVACS Krisztian <hidden@xxxxxxxxxx>
---
include/net/inet_sock.h | 2 +-
include/net/tcp.h | 1 +
net/ipv4/inet_connection_sock.c | 2 ++
net/ipv4/syncookies.c | 1 +
net/ipv4/tcp_output.c | 2 +-
5 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 517efe7..d7e2a52 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -61,8 +61,8 @@ struct inet_request_sock {
struct request_sock req;
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
u16 inet6_rsk_offset;
- /* 2 bytes hole, try to pack */
#endif
+ __be16 loc_port;
__be32 loc_addr;
__be32 rmt_addr;
__be16 rmt_port;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 54053de..6271023 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -980,6 +980,7 @@ static inline void tcp_openreq_init(struct request_sock *req,
ireq->acked = 0;
ireq->ecn_ok = 0;
ireq->rmt_port = tcp_hdr(skb)->source;
+ ireq->loc_port = tcp_hdr(skb)->dest;
}
extern void tcp_enter_memory_pressure(void);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 5c93359..43c37bf 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -501,6 +501,8 @@ struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
newicsk->icsk_bind_hash = NULL;
inet_sk(newsk)->dport = inet_rsk(req)->rmt_port;
+ inet_sk(newsk)->num = ntohs(inet_rsk(req)->loc_port);
+ inet_sk(newsk)->sport = inet_rsk(req)->loc_port;
newsk->sk_write_space = sk_stream_write_space;
newicsk->icsk_retransmits = 0;
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index a0f6fdb..6e84243 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -223,6 +223,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
treq->rcv_isn = ntohl(th->seq) - 1;
treq->snt_isn = cookie;
req->mss = mss;
+ ireq->loc_port = th->dest;
ireq->rmt_port = th->source;
ireq->loc_addr = ip_hdr(skb)->daddr;
ireq->rmt_addr = ip_hdr(skb)->saddr;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 666d8a5..06f26af 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2153,7 +2153,7 @@ struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
th->syn = 1;
th->ack = 1;
TCP_ECN_make_synack(req, th);
- th->source = inet_sk(sk)->sport;
+ th->source = ireq->loc_port;
th->dest = ireq->rmt_port;
TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn;
TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1;
-
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