ssh: update to OpenSSH 9.1p1

Release notes are available at https://www.openssh.com/txt/release-9.1

9.1 contains fixes for three minor memory safety problems; these have
lready been merged to the copy of OpenSSH 9.0 that is in the FreeBSD base
system.

Some highlights copied from the release notes:

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

* ssh(1), sshd(8): SetEnv directives in ssh_config and sshd_config
are now first-match-wins to match other directives. Previously
if an environment variable was multiply specified the last set
value would have been used. bz3438

* ssh-keygen(8): ssh-keygen -A (generate all default host key types)
will no longer generate DSA keys, as these are insecure and have
not been used by default for some years.

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

* ssh(1), sshd(8): add a RequiredRSASize directive to set a minimum
RSA key length. Keys below this length will be ignored for user
authentication and for host authentication in sshd(8).

* sftp-server(8): add a "users-groups-by-id@openssh.com" extension
request that allows the client to obtain user/group names that
correspond to a set of uids/gids.

* sftp(1): use "users-groups-by-id@openssh.com" sftp-server
extension (when available) to fill in user/group names for
directory listings.

* sftp-server(8): support the "home-directory" extension request
defined in draft-ietf-secsh-filexfer-extensions-00. This overlaps
a bit with the existing "expand-path@openssh.com", but some other
clients support it.

* ssh-keygen(1), sshd(8): allow certificate validity intervals,
sshsig verification times and authorized_keys expiry-time options
to accept dates in the UTC time zone in addition to the default
of interpreting them in the system time zone. YYYYMMDD and
YYMMDDHHMM[SS] dates/times will be interpreted as UTC if suffixed
with a 'Z' character.

Also allow certificate validity intervals to be specified in raw
seconds-since-epoch as hex value, e.g. -V 0x1234:0x4567890. This
is intended for use by regress tests and other tools that call
ssh-keygen as part of a CA workflow. bz3468

* sftp(1): allow arguments to the sftp -D option, e.g. sftp -D
"/usr/libexec/sftp-server -el debug3"

* ssh-keygen(1): allow the existing -U (use agent) flag to work
with "-Y sign" operations, where it will be interpreted to require
that the private keys is hosted in an agent; bz3429

MFC after: 2 weeks
Relnotes: Yes
Sponsored by: The FreeBSD Foundation

ssh: update to OpenSSH v8.9p1

Release notes are available at https://www.openssh.com/txt/release-8.9

Some highlights:

* ssh(1), sshd(8), ssh-add(1), ssh-agent(1): add a system for
restricting forwarding and use of keys added to ssh-agent(1)

* ssh(1), sshd(8): add the sntrup761x25519-sha512@openssh.com hybrid
ECDH/x25519 + Streamlined NTRU Prime post-quantum KEX to the
default KEXAlgorithms list (after the ECDH methods but before the
prime-group DH ones). The next release of OpenSSH is likely to
make this key exchange the default method.

* sshd(8), portable OpenSSH only: this release removes in-built
support for MD5-hashed passwords. If you require these on your
system then we recommend linking against libxcrypt or similar.

Future deprecation notice
=========================

A near-future release of OpenSSH will switch scp(1) from using the
legacy scp/rcp protocol to using SFTP by default.

Legacy scp/rcp performs wildcard expansion of remote filenames (e.g.
"scp host:* .") through the remote shell. This has the side effect of
requiring double quoting of shell meta-characters in file names
included on scp(1) command-lines, otherwise they could be interpreted
as shell commands on the remote side.

MFC after: 1 month
Relnotes: Yes
Sponsored by: The FreeBSD Foundation

ssh: regen sk_config.h after 73104d583850

ssh: use standalone config file for security key support

An upcoming OpenSSH update has multiple config.h settings that change
depending on whether builtin security key support is enabled. Prepare
for this by moving ENABLE_SK_INTERNAL to a new sk_config.h header
(similar to the approach used for optional krb5 support) and optionally
including that, instead of defining the macro directly from CFLAGS.

Reviewed by: kevans
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34407

ssh: update to OpenSSH v8.9p1

Release notes are available at https://www.openssh.com/txt/release-8.9

Some highlights:

* ssh(1), sshd(8), ssh-add(1), ssh-agent(1): add a system for
restricting forwarding and use of keys added to ssh-agent(1)

* ssh(1), sshd(8): add the sntrup761x25519-sha512@openssh.com hybrid
ECDH/x25519 + Streamlined NTRU Prime post-quantum KEX to the
default KEXAlgorithms list (after the ECDH methods but before the
prime-group DH ones). The next release of OpenSSH is likely to
make this key exchange the default method.

* sshd(8), portable OpenSSH only: this release removes in-built
support for MD5-hashed passwords. If you require these on your
system then we recommend linking against libxcrypt or similar.

Future deprecation notice
=========================

A near-future release of OpenSSH will switch scp(1) from using the
legacy scp/rcp protocol to using SFTP by default.

Legacy scp/rcp performs wildcard expansion of remote filenames (e.g.
"scp host:* .") through the remote shell. This has the side effect of
requiring double quoting of shell meta-characters in file names
included on scp(1) command-lines, otherwise they could be interpreted
as shell commands on the remote side.

MFC after: 1 month
Relnotes: Yes
Sponsored by: The FreeBSD Foundation

ssh: regen sk_config.h after 73104d583850

ssh: use standalone config file for security key support

An upcoming OpenSSH update has multiple config.h settings that change
depending on whether builtin security key support is enabled. Prepare
for this by moving ENABLE_SK_INTERNAL to a new sk_config.h header
(similar to the approach used for optional krb5 support) and optionally
including that, instead of defining the macro directly from CFLAGS.

Reviewed by: kevans
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34407

ssh: regen sk_config.h after 73104d583850

ssh: use standalone config file for security key support

An upcoming OpenSSH update has multiple config.h settings that change
depending on whether builtin security key support is enabled. Prepare
for this by moving ENABLE_SK_INTERNAL to a new sk_config.h header
(similar to the approach used for optional krb5 support) and optionally
including that, instead of defining the macro directly from CFLAGS.

Reviewed by: kevans
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34407