The branch stable/13 has been updated by rew: URL: https://cgit.FreeBSD.org/src/commit/?id=7205809809e70db0abf2cecaf7f5e056650315bb
commit 7205809809e70db0abf2cecaf7f5e056650315bb Author: Robert Wing <[email protected]> AuthorDate: 2022-01-09 01:07:50 +0000 Commit: Robert Wing <[email protected]> CommitDate: 2022-02-10 19:31:33 +0000 syncache: accept packet with no SA when TCP_MD5SIG is set When TCP_MD5SIG is set on a socket, all packets are dropped that don't contain an MD5 signature. Relax this behavior to accept a non-signed packet when a security association doesn't exist with the peer. This is useful when a listen socket set with TCP_MD5SIG wants to handle connections protected with and without MD5 signatures. Reviewed by: bz (previous version) Sponsored by: nepustil.net Sponsored by: Klara Inc. Differential Revision: https://reviews.freebsd.org/D33227 (cherry picked from commit eb18708ec8c7e1de6a05aba41971659549991b10) --- share/man/man4/tcp.4 | 6 +++++- sys/netinet/tcp_syncache.c | 30 ++++++++++++++++++------------ sys/netipsec/xform_tcp.c | 5 +++++ 3 files changed, 28 insertions(+), 13 deletions(-) diff --git a/share/man/man4/tcp.4 b/share/man/man4/tcp.4 index e49df5319efb..3fe2753bf408 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 June 27, 2021 +.Dd January 8, 2022 .Dt TCP 4 .Os .Sh NAME @@ -339,6 +339,10 @@ This entry can only be specified on a per-host basis at this time. .Pp If an SADB entry cannot be found for the destination, the system does not send any outgoing segments and drops any inbound segments. +However, during connection negotiation, a non-signed segment will be accepted if +an SADB entry does not exist between hosts. +When a non-signed segment is accepted, the established connection is not +protected with MD5 digests. .It Dv TCP_STATS Manage collection of connection level statistics using the .Xr stats 3 diff --git a/sys/netinet/tcp_syncache.c b/sys/netinet/tcp_syncache.c index a1102574b325..e7fb8da52216 100644 --- a/sys/netinet/tcp_syncache.c +++ b/sys/netinet/tcp_syncache.c @@ -1513,19 +1513,25 @@ syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th, #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) /* - * If listening socket requested TCP digests, check that received - * SYN has signature and it is correct. If signature doesn't match - * or TCP_SIGNATURE support isn't enabled, drop the packet. + * When the socket is TCP-MD5 enabled check that, + * - a signed packet is valid + * - a non-signed packet does not have a security association + * + * If a signed packet fails validation or a non-signed packet has a + * security association, the packet will be dropped. */ if (ltflags & TF_SIGNATURE) { - if ((to->to_flags & TOF_SIGNATURE) == 0) { - TCPSTAT_INC(tcps_sig_err_nosigopt); - goto done; + if (to->to_flags & TOF_SIGNATURE) { + if (!TCPMD5_ENABLED() || + TCPMD5_INPUT(m, th, to->to_signature) != 0) + goto done; + } else { + if (TCPMD5_ENABLED() && + TCPMD5_INPUT(m, NULL, NULL) != ENOENT) + goto done; } - if (!TCPMD5_ENABLED() || - TCPMD5_INPUT(m, th, to->to_signature) != 0) - goto done; - } + } else if (to->to_flags & TOF_SIGNATURE) + goto done; #endif /* TCP_SIGNATURE */ /* * See if we already have an entry for this connection. @@ -1723,11 +1729,11 @@ skip_alloc: } #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) /* - * If listening socket requested TCP digests, flag this in the + * If incoming packet has an MD5 signature, flag this in the * syncache so that syncache_respond() will do the right thing * with the SYN+ACK. */ - if (ltflags & TF_SIGNATURE) + if (to->to_flags & TOF_SIGNATURE) sc->sc_flags |= SCF_SIGNATURE; #endif /* TCP_SIGNATURE */ if (to->to_flags & TOF_SACKPERM) diff --git a/sys/netipsec/xform_tcp.c b/sys/netipsec/xform_tcp.c index b53544cd00fb..ce2552f0a205 100644 --- a/sys/netipsec/xform_tcp.c +++ b/sys/netipsec/xform_tcp.c @@ -269,6 +269,11 @@ tcp_ipsec_input(struct mbuf *m, struct tcphdr *th, u_char *buf) KMOD_TCPSTAT_INC(tcps_sig_err_buildsig); return (ENOENT); } + if (buf == NULL) { + key_freesav(&sav); + KMOD_TCPSTAT_INC(tcps_sig_err_nosigopt); + return (EACCES); + } /* * tcp_input() operates with TCP header fields in host * byte order. We expect them in network byte order.
