Announce: OpenSSH 9.2 released

Fri Feb 3 00:15:12 AEDT 2023

OpenSSH 9.2 has just been released. It will be available from the
mirrors listed at https://www.openssh.com/ shortly.

OpenSSH is a 100% complete SSH protocol 2.0 implementation and
includes sftp client and server support.

Once again, we would like to thank the OpenSSH community for their
continued support of the project, especially those who contributed
code or patches, reported bugs, tested snapshots or donated to the
project. More information on donations may be found at:
https://www.openssh.com/donations.html

Changes since OpenSSH 9.1
=========================

This release fixes a number of security bugs.

Security
========

This release contains fixes for two security problems and a memory
safety problem. The memory safety problem is not believed to be
exploitable, but we report most network-reachable memory faults as
security bugs.

 * sshd(8): fix a pre-authentication double-free memory fault
   introduced in OpenSSH 9.1. This is not believed to be exploitable,
   and it occurs in the unprivileged pre-auth process that is
   subject to chroot(2) and is further sandboxed on most major
   platforms.

 * ssh(8): in OpenSSH releases after 8.7, the PermitRemoteOpen option
   would ignore its first argument unless it was one of the special
   keywords "any" or "none", causing the permission list to fail open
   if only one permission was specified. bz3515

 * ssh(1): if the CanonicalizeHostname and CanonicalizePermittedCNAMEs
   options were enabled, and the system/libc resolver did not check
   that names in DNS responses were valid, then use of these options
   could allow an attacker with control of DNS to include invalid
   characters (possibly including wildcards) in names added to
   known_hosts files when they were updated. These names would still
   have to match the CanonicalizePermittedCNAMEs allow-list, so
   practical exploitation appears unlikely.

Potentially-incompatible changes
--------------------------------

 * ssh(1): add a new EnableEscapeCommandline ssh_config(5) option that
   controls whether the client-side ~C escape sequence that provides a
   command-line is available. Among other things, the ~C command-line
   could be used to add additional port-forwards at runtime.

   This option defaults to "no", disabling the ~C command-line that
   was previously enabled by default. Turning off the command-line
   allows platforms that support sandboxing of the ssh(1) client
   (currently only OpenBSD) to use a stricter default sandbox policy.

New features
------------

 * sshd(8): add support for channel inactivity timeouts via a new
   sshd_config(5) ChannelTimeout directive. This allows channels that
   have not seen traffic in a configurable interval to be
   automatically closed. Different timeouts may be applied to session,
   X11, agent and TCP forwarding channels.

 * sshd(8): add a sshd_config UnusedConnectionTimeout option to
   terminate client connections that have no open channels for a
   length of time. This complements the ChannelTimeout option above.

 * sshd(8): add a -V (version) option to sshd like the ssh client has.

 * ssh(1): add a "Host" line to the output of ssh -G showing the
   original hostname argument. bz3343

 * scp(1), sftp(1): add a -X option to both scp(1) and sftp(1) to
   allow control over some SFTP protocol parameters: the copy buffer
   length and the number of in-flight requests, both of which are used
   during upload/download. Previously these could be controlled in
   sftp(1) only. This makes them available in both SFTP protocol
   clients using the same option character sequence.

 * ssh-keyscan(1): allow scanning of complete CIDR address ranges,
   e.g.  "ssh-keyscan 192.168.0.0/24". If a CIDR range is passed, then
   it will be expanded to all possible addresses in the range
   including the all-0s and all-1s addresses. bz#976

 * ssh(1): support dynamic remote port forwarding in escape
   command-line's -R processing. bz#3499

Bugfixes
--------

 * ssh(1): when restoring non-blocking mode to stdio fds, restore
   exactly the flags that ssh started with and don't just clobber them
   with zero, as this could also remove the append flag from the set.
   bz3523

 * ssh(1): avoid printf("%s", NULL) if using UserKnownHostsFile=none
   and a hostkey in one of the system known hosts file changes.

 * scp(1): switch scp from using pipes to a socket-pair for
   communication with its ssh sub-processes, matching how sftp(1)
   operates.

 * sshd(8): clear signal mask early in main(); sshd may have been
   started with one or more signals masked (sigprocmask(2) is not
   cleared on fork/exec) and this could interfere with various things,
   e.g. the login grace timer. Execution environments that fail to
   clear the signal mask before running sshd are clearly broken, but
   apparently they do exist.

 * ssh(1): warn if no host keys for hostbased auth can be loaded.

 * sshd(8): Add server debugging for hostbased auth that is queued and
   sent to the client after successful authentication, but also logged
   to assist in diagnosis of HostbasedAuthentication problems. bz3507

 * ssh(1): document use of the IdentityFile option as being usable to
   list public keys as well as private keys. GHPR352

 * sshd(8): check for and disallow MaxStartups values less than or
   equal to zero during config parsing, rather than failing later at
   runtime.  bz3489

 * ssh-keygen(1): fix parsing of hex cert expiry times specified on
   the command-line when acting as a CA.

 * scp(1): when scp(1) is using the SFTP protocol for transport (the
   default), better match scp/rcp's handling of globs that don't match
   the globbed characters but do match literally (e.g. trying to
   transfer a file named "foo.[1]"). Previously scp(1) in SFTP mode
   would not match these pathnames but legacy scp/rcp mode would.
   bz3488

 * ssh-agent(1): document the "-O no-restrict-websafe" command-line
   option.

 * ssh(1): honour user's umask(2) if it is more restrictive then the
   ssh default (022).

Portability
-----------

 * sshd(8): allow writev(2) in the Linux seccomp sandbox. This seems
   to be used by recent glibcs at least in some configurations during
   error conditions. bz3512.

 * sshd(8): simply handling of SSH_CONNECTION PAM env var, removing
   global variable and checking the return value from pam_putenv.
   bz3508

 * sshd(8): disable SANDBOX_SECCOMP_FILTER_DEBUG that was mistakenly
   enabled during the OpenSSH 9.1 release cycle.

 * misc: update autotools and regenerate the config files using the
   latest autotools

 * all: use -fzero-call-used-regs=used on clang 15 instead of
   -fzero-call-used-reg=all, as some versions of clang 15 have
   miscompile code when it was enabled. bz3475

 * sshd(8): defer PRNG seeding until after the initial closefrom(2)
   call. PRNG seeding will initialize OpenSSL, and some engine
   providers (e.g. Intel's QAT) will open descriptors for their own
   use that closefrom(2) could clobber. bz3483

 * misc: in the poll(2)/ppoll(2) compatibility code, avoid assuming
   the layout of fd_set.

 * sftp-server(8), ssh-agent(1): fix ptrace(2) disabling on older
   FreeBSD kernels. Some versions do not support using id 0 to refer
   to the current PID for procctl, so try again with getpid()
   explicitly before failing.

 * configure.ac: fix -Wstrict-prototypes in configure test code.
   Clang 16 now warns on this and legacy prototypes will be removed
   in C23. GHPR355

 * configure.ac: fix setres*id checks to work with clang-16. glibc
   has the prototypes for setresuid behind _GNU_SOURCE, and clang 16
   will error out on implicit function definitions. bz3497

Checksums:
==========

- SHA1 (openssh-9.2.tar.gz) = e4b806b7c81b87d6c90afe97b3d016ba6cf3ba1c
- SHA256 (openssh-9.2.tar.gz) = yYe9uaaWSeetXGXOxuaaEiIsLnvITmGW+l5dgMZb9QU=

- SHA1 (openssh-9.2p1.tar.gz) = 3b172b8e971773a7018bbf3231f6589ae539ca4b
- SHA256 (openssh-9.2p1.tar.gz) = P2bb8WVftF9Q4cVtpiqwEhjCKIB7ITONY068351xz0Y=

Please note that the SHA256 signatures are base64 encoded and not
hexadecimal (which is the default for most checksum tools). The PGP
key used to sign the releases is available from the mirror sites:
https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc

Reporting Bugs:
===============

- Please read https://www.openssh.com/report.html
  Security bugs should be reported directly to openssh at openssh.com