git: 40f41ece765d - main - tcp: improve handling of SYN segments in SYN-SENT state

[Michael Tuexen]

The branch main has been updated by tuexen:

URL: https://cgit.FreeBSD.org/src/commit/?id=40f41ece765dc0b0907ca90796a1af4f4f89b2a0

commit 40f41ece765dc0b0907ca90796a1af4f4f89b2a0
Author:     Michael Tuexen <tuexen at FreeBSD.org>
AuthorDate: 2021-03-22 14:58:49 +0000
Commit:     Michael Tuexen <tuexen at FreeBSD.org>
CommitDate: 2021-03-22 14:58:49 +0000

    tcp: improve handling of SYN segments in SYN-SENT state
    
    Ensure that the stack does not generate a DSACK block for user
    data received on a SYN segment in SYN-SENT state.
    
    Reviewed by:            rscheff
    MFC after:              3 days
    Differential Revision:  https://reviews.freebsd.org/D29376
    Sponsored by:           Netflix, Inc.
---
 sys/netinet/tcp_input.c       | 4 +++-
 sys/netinet/tcp_stacks/bbr.c  | 4 +++-
 sys/netinet/tcp_stacks/rack.c | 4 +++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c
index 7dfe1dbd4e4f..bdc0e872c36e 100644
--- a/sys/netinet/tcp_input.c
+++ b/sys/netinet/tcp_input.c
@@ -3179,7 +3179,9 @@ dodata:							/* XXX */
 			thflags = tcp_reass(tp, th, &temp, &tlen, m);
 			tp->t_flags |= TF_ACKNOW;
 		}
-		if ((tp->t_flags & TF_SACK_PERMIT) && (save_tlen > 0)) {
+		if ((tp->t_flags & TF_SACK_PERMIT) &&
+		    (save_tlen > 0) &&
+		    TCPS_HAVEESTABLISHED(tp->t_state)) {
 			if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) {
 				/*
 				 * DSACK actually handled in the fastpath
diff --git a/sys/netinet/tcp_stacks/bbr.c b/sys/netinet/tcp_stacks/bbr.c
index f9535935a9db..673dee911c87 100644
--- a/sys/netinet/tcp_stacks/bbr.c
+++ b/sys/netinet/tcp_stacks/bbr.c
@@ -8371,7 +8371,9 @@ bbr_process_data(struct mbuf *m, struct tcphdr *th, struct socket *so,
 			thflags = tcp_reass(tp, th, &temp, &tlen, m);
 			tp->t_flags |= TF_ACKNOW;
 		}
-		if ((tp->t_flags & TF_SACK_PERMIT) && (save_tlen > 0)) {
+		if ((tp->t_flags & TF_SACK_PERMIT) &&
+		    (save_tlen > 0) &&
+		    TCPS_HAVEESTABLISHED(tp->t_state)) {
 			if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) {
 				/*
 				 * DSACK actually handled in the fastpath
diff --git a/sys/netinet/tcp_stacks/rack.c b/sys/netinet/tcp_stacks/rack.c
index 5bea540c6ab6..beae1bf9cba7 100644
--- a/sys/netinet/tcp_stacks/rack.c
+++ b/sys/netinet/tcp_stacks/rack.c
@@ -8683,7 +8683,9 @@ rack_process_data(struct mbuf *m, struct tcphdr *th, struct socket *so,
 			thflags = tcp_reass(tp, th, &temp, &tlen, m);
 			tp->t_flags |= TF_ACKNOW;
 		}
-                if ((tp->t_flags & TF_SACK_PERMIT) && (save_tlen > 0)) {
+		if ((tp->t_flags & TF_SACK_PERMIT) &&
+		    (save_tlen > 0) &&
+		    TCPS_HAVEESTABLISHED(tp->t_state)) {
                         if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) {
                                 /*
                                  * DSACK actually handled in the fastpath