ipv6: tcp: fix flowlabel value in ACK messages send from TIME_WAIT

This patch is following the commit b903d324bee262 (ipv6: tcp: fix TCLASS
value in ACK messages sent from TIME_WAIT).

For the same reason than tclass, we have to store the flow label in the
inet_timewait_sock to provide consistency of flow label on the last ACK.

Signed-off-by: Florent Fourcot <florent.fourcot@enst-bretagne.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_timewait_sock.h

@@ -133,9 +133,9 @@ struct inet_timewait_sock {
 	/* And these are ours. */
 	unsigned int		tw_ipv6only     : 1,
 				tw_transparent  : 1,
-				tw_pad		: 6,	/* 6 bits hole */
-				tw_tos		: 8,
-				tw_pad2		: 16;	/* 16 bits hole */
+				tw_flowlabel	: 20,
+				tw_pad		: 2,	/* 2 bits hole */
+				tw_tos		: 8;
 	kmemcheck_bitfield_end(flags);
 	u32			tw_ttd;
 	struct inet_bind_bucket	*tw_tb;

net/ipv4/tcp_minisocks.c

@@ -297,6 +297,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
 			tw->tw_v6_daddr = sk->sk_v6_daddr;
 			tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 			tw->tw_tclass = np->tclass;
+			tw->tw_flowlabel = np->flow_label >> 12;
 			tw->tw_ipv6only = np->ipv6only;
 		}
 #endif

net/ipv6/tcp_ipv6.c

@@ -724,7 +724,8 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 
 static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
 				 u32 tsval, u32 tsecr,
-				 struct tcp_md5sig_key *key, int rst, u8 tclass)
+				 struct tcp_md5sig_key *key, int rst, u8 tclass,
+				 u32 label)
 {
 	const struct tcphdr *th = tcp_hdr(skb);
 	struct tcphdr *t1;
@@ -786,6 +787,7 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
 	memset(&fl6, 0, sizeof(fl6));
 	fl6.daddr = ipv6_hdr(skb)->saddr;
 	fl6.saddr = ipv6_hdr(skb)->daddr;
+	fl6.flowlabel = label;
 
 	buff->ip_summed = CHECKSUM_PARTIAL;
 	buff->csum = 0;
@@ -871,7 +873,7 @@ 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, 0, key, 1, 0);
+	tcp_v6_send_response(skb, seq, ack_seq, 0, 0, 0, key, 1, 0, 0);
 
 #ifdef CONFIG_TCP_MD5SIG
 release_sk1:
@@ -884,9 +886,11 @@ release_sk1:
 
 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)
+			    struct tcp_md5sig_key *key, u8 tclass,
+			    u32 label)
 {
-	tcp_v6_send_response(skb, seq, ack, win, tsval, tsecr, key, 0, tclass);
+	tcp_v6_send_response(skb, seq, ack, win, tsval, tsecr, key, 0, tclass,
+			     label);
 }
 
 static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
@@ -898,7 +902,7 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
 			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);
+			tw->tw_tclass, (tw->tw_flowlabel << 12));
 
 	inet_twsk_put(tw);
 }
@@ -908,7 +912,8 @@ static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 {
 	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);
+			tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr),
+			0, 0);
 }