Date: Wed, 14 Jul 2021 07:44:21 GMT From: Michael Tuexen <tuexen@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: b9dc12859790 - stable/12 - tcp: tolerate missing timestamps Message-ID: <202107140744.16E7iLd0018223@gitrepo.freebsd.org>
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The branch stable/12 has been updated by tuexen: URL: https://cgit.FreeBSD.org/src/commit/?id=b9dc1285979058cb2751675d926a773513e83fc8 commit b9dc1285979058cb2751675d926a773513e83fc8 Author: Michael Tuexen <tuexen@FreeBSD.org> AuthorDate: 2021-06-11 18:14:34 +0000 Commit: Michael Tuexen <tuexen@FreeBSD.org> CommitDate: 2021-07-14 07:43:16 +0000 tcp: tolerate missing timestamps Some TCP stacks negotiate TS support, but do not send TS at all or not for keep-alive segments. Since this includes modern widely deployed stacks, tolerate the violation of RFC 7323 per default. Reviewed by: rgrimes, rrs, rscheff Differential Revision: https://reviews.freebsd.org/D30740 Sponsored by: Netflix, Inc. (cherry picked from commit 870af3f4dc57a6bbfc03f6a49ca0d5b7ff1b975a) --- share/man/man4/tcp.4 | 6 ++++-- sys/netinet/tcp_subr.c | 9 ++++++++- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/share/man/man4/tcp.4 b/share/man/man4/tcp.4 index e1e87afd7fd6..ad7e3f117d68 100644 --- a/share/man/man4/tcp.4 +++ b/share/man/man4/tcp.4 @@ -34,7 +34,7 @@ .\" From: @(#)tcp.4 8.1 (Berkeley) 6/5/93 .\" $FreeBSD$ .\" -.Dd January 14, 2021 +.Dd June 27, 2021 .Dt TCP 4 .Os .Sh NAME @@ -343,7 +343,9 @@ segments belonging to connections for which support of .Tn TCP timestamps has been negotiated. -(default is 0, i.e., the missing of timestamps is not tolerated). +As of June 2021, several TCP stacks are known to violate RFC 7323, including +modern widely deployed ones. +Therefore the default is 1, i.e., the missing of timestamps is tolerated. .It Dv TCPCTL_MSSDFLT .Pq Va mssdflt The default value used for the maximum segment size diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c index 5394a63c1a12..c82a5bf21a15 100644 --- a/sys/netinet/tcp_subr.c +++ b/sys/netinet/tcp_subr.c @@ -195,7 +195,14 @@ SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_do_rfc1323), 0, "Enable rfc1323 (high performance TCP) extensions"); -VNET_DEFINE(int, tcp_tolerate_missing_ts) = 0; +/* + * As of June 2021, several TCP stacks violate RFC 7323 from September 2014. + * Some stacks negotiate TS, but never send them after connection setup. Some + * stacks negotiate TS, but don't send them when sending keep-alive segments. + * These include modern widely deployed TCP stacks. + * Therefore tolerating violations for now... + */ +VNET_DEFINE(int, tcp_tolerate_missing_ts) = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, tolerate_missing_ts, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_tolerate_missing_ts), 0, "Tolerate missing TCP timestamps");
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