svn commit: r347081 - in stable/12/sys/netinet: . tcp_stacks

[Michael Tuexen]

Author: tuexen
Date: Sat May  4 09:07:53 2019
New Revision: 347081
URL: https://svnweb.freebsd.org/changeset/base/347081

Log:
  MFC r343525:
  Fix the detection of ECN-setup SYN-ACK packets.
  
  RFC 3168 defines an ECN-setup SYN-ACK packet as on with the ECE flags
  set and the CWR flags not set. The code was only checking if ECE flag
  is set. This patch adds the check to verify that the CWR flags is not
  set.
  
  Submitted by:		Richard Scheffenegger
  Reviewed by:		tuexen@
  Differential Revision:	https://reviews.freebsd.org/D18996

Modified:
  stable/12/sys/netinet/tcp_input.c
  stable/12/sys/netinet/tcp_stacks/rack.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/netinet/tcp_input.c
==============================================================================
--- stable/12/sys/netinet/tcp_input.c	Sat May  4 09:01:56 2019	(r347080)
+++ stable/12/sys/netinet/tcp_input.c	Sat May  4 09:07:53 2019	(r347081)
@@ -2027,7 +2027,8 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, stru
 			else
 				tp->t_flags |= TF_ACKNOW;
 
-			if ((thflags & TH_ECE) && V_tcp_do_ecn) {
+			if (((thflags & (TH_CWR | TH_ECE)) == TH_ECE) &&
+			    V_tcp_do_ecn) {
 				tp->t_flags |= TF_ECN_PERMIT;
 				TCPSTAT_INC(tcps_ecn_shs);
 			}

Modified: stable/12/sys/netinet/tcp_stacks/rack.c
==============================================================================
--- stable/12/sys/netinet/tcp_stacks/rack.c	Sat May  4 09:01:56 2019	(r347080)
+++ stable/12/sys/netinet/tcp_stacks/rack.c	Sat May  4 09:07:53 2019	(r347081)
@@ -5245,7 +5245,8 @@ rack_do_syn_sent(struct mbuf *m, struct tcphdr *th, st
 			tp->t_flags |= TF_ACKNOW;
 		}
 
-		if ((thflags & TH_ECE) && V_tcp_do_ecn) {
+		if (((thflags & (TH_CWR | TH_ECE)) == TH_ECE) &&
+		    V_tcp_do_ecn) {
 			tp->t_flags |= TF_ECN_PERMIT;
 			TCPSTAT_INC(tcps_ecn_shs);
 		}