Merge tag 'v4.19-rc5' of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into fbdev-for-next

Sync with upstream (which now contains fbdev-v4.19 changes) to
prepare a base for fbdev-v4.20 changes.

1 files changed, 26 insertions, 6 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index bea17f1e8302..44c09eddbb78 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -155,12 +155,26 @@ int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
 	   and use initial timestamp retrieved from peer table.
 	 */
 	if (tcptw->tw_ts_recent_stamp &&
-	    (!twp || (reuse && get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
-		tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
-		if (tp->write_seq == 0)
-			tp->write_seq = 1;
-		tp->rx_opt.ts_recent	   = tcptw->tw_ts_recent;
-		tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
+	    (!twp || (reuse && time_after32(ktime_get_seconds(),
+					    tcptw->tw_ts_recent_stamp)))) {
+		/* In case of repair and re-using TIME-WAIT sockets we still
+		 * want to be sure that it is safe as above but honor the
+		 * sequence numbers and time stamps set as part of the repair
+		 * process.
+		 *
+		 * Without this check re-using a TIME-WAIT socket with TCP
+		 * repair would accumulate a -1 on the repair assigned
+		 * sequence number. The first time it is reused the sequence
+		 * is -1, the second time -2, etc. This fixes that issue
+		 * without appearing to create any others.
+		 */
+		if (likely(!tp->repair)) {
+			tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2;
+			if (tp->write_seq == 0)
+				tp->write_seq = 1;
+			tp->rx_opt.ts_recent	   = tcptw->tw_ts_recent;
+			tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
+		}
 		sock_hold(sktw);
 		return 1;
 	}
@@ -2503,6 +2517,12 @@ static int __net_init tcp_sk_init(struct net *net)
 		if (res)
 			goto fail;
 		sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
+
+		/* Please enforce IP_DF and IPID==0 for RST and
+		 * ACK sent in SYN-RECV and TIME-WAIT state.
+		 */
+		inet_sk(sk)->pmtudisc = IP_PMTUDISC_DO;
+
 		*per_cpu_ptr(net->ipv4.tcp_sk, cpu) = sk;
 	}