tcp: send packets with a socket timestamp

A socket timestamp is a sum of the global tcp_time_stamp and
a per-socket offset.

A socket offset is added in places where externally visible
tcp timestamp option is parsed/initialized.

Connections in the SYN_RECV state are not supported, global
tcp_time_stamp is used for them, because repair mode doesn't support
this state. In a future it can be implemented by the similar way
as for TIME_WAIT sockets.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 9 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index bbb28ae..9b64600 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -713,7 +713,8 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 #endif
 
 static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
-				 u32 ts, struct tcp_md5sig_key *key, int rst, u8 tclass)
+				 u32 tsval, u32 tsecr,
+				 struct tcp_md5sig_key *key, int rst, u8 tclass)
 {
 	const struct tcphdr *th = tcp_hdr(skb);
 	struct tcphdr *t1;
@@ -725,7 +726,7 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
 	struct dst_entry *dst;
 	__be32 *topt;
 
-	if (ts)
+	if (tsecr)
 		tot_len += TCPOLEN_TSTAMP_ALIGNED;
 #ifdef CONFIG_TCP_MD5SIG
 	if (key)
@@ -755,11 +756,11 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
 
 	topt = (__be32 *)(t1 + 1);
 
-	if (ts) {
+	if (tsecr) {
 		*topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
 				(TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
-		*topt++ = htonl(tcp_time_stamp);
-		*topt++ = htonl(ts);
+		*topt++ = htonl(tsval);
+		*topt++ = htonl(tsecr);
 	}
 
 #ifdef CONFIG_TCP_MD5SIG
@@ -860,7 +861,7 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
 		ack_seq = ntohl(th->seq) + th->syn + th->fin + skb->len -
 			  (th->doff << 2);
 
-	tcp_v6_send_response(skb, seq, ack_seq, 0, 0, key, 1, 0);
+	tcp_v6_send_response(skb, seq, ack_seq, 0, 0, 0, key, 1, 0);
 
 #ifdef CONFIG_TCP_MD5SIG
 release_sk1:
@@ -871,10 +872,11 @@ release_sk1:
 #endif
 }
 
-static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 win, u32 ts,
+static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
+			    u32 win, u32 tsval, u32 tsecr,
 			    struct tcp_md5sig_key *key, u8 tclass)
 {
-	tcp_v6_send_response(skb, seq, ack, win, ts, key, 0, tclass);
+	tcp_v6_send_response(skb, seq, ack, win, tsval, tsecr, key, 0, tclass);
 }
 
 static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
@@ -884,6 +886,7 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
 
 	tcp_v6_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
 			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
+			tcp_time_stamp + tcptw->tw_ts_offset,
 			tcptw->tw_ts_recent, tcp_twsk_md5_key(tcptw),
 			tw->tw_tclass);
 
@@ -893,7 +896,8 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
 static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 				  struct request_sock *req)
 {
-	tcp_v6_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd, req->ts_recent,
+	tcp_v6_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1,
+			req->rcv_wnd, tcp_time_stamp, req->ts_recent,
 			tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr), 0);
 }