openssh: Update to 9.8p1

Highlights from the release notes are reproduced below. Some security
and bug fixes were previously merged into FreeBSD and have been elided.
See the upstream release notes for full details
(https://www.openssh.com/releasenotes.html).

Future deprecation notice

OpenSSH plans to remove support for the DSA signature algorithm in
early 2025.

Potentially-incompatible changes

• sshd(8): the server will now block client addresses that repeatedly fail authentication, repeatedly connect without ever completing authentication or that crash the server. See the discussion of PerSourcePenalties below for more information. Operators of servers that accept connections from many users, or servers that accept connections from addresses behind NAT or proxies may need to consider these settings.
• sshd(8): the server has been split into a listener binary, sshd(8), and a per-session binary "sshd-session". This allows for a much smaller listener binary, as it no longer needs to support the SSH protocol. As part of this work, support for disabling privilege separation (which previously required code changes to disable) and disabling re-execution of sshd(8) has been removed. Further separation of sshd-session into additional, minimal binaries is planned for the future.
• sshd(8): several log messages have changed. In particular, some log messages will be tagged with as originating from a process named "sshd-session" rather than "sshd".
• ssh-keyscan(1): this tool previously emitted comment lines containing the hostname and SSH protocol banner to standard error. This release now emits them to standard output, but adds a new "-q" flag to silence them altogether.
• sshd(8): (portable OpenSSH only) sshd will no longer use argv[0] as the PAM service name. A new "PAMServiceName" sshd_config(5) directive allows selecting the service name at runtime. This defaults to "sshd". bz2101

New features

• sshd(8): sshd(8) will now penalise client addresses that, for various reasons, do not successfully complete authentication. This feature is controlled by a new sshd_config(5) PerSourcePenalties option and is on by default.
• ssh(8): allow the HostkeyAlgorithms directive to disable the implicit fallback from certificate host key to plain host keys.

Portability

• sshd(8): expose SSH_AUTH_INFO_0 always to PAM auth modules unconditionally. The previous behaviour was to expose it only when particular authentication methods were in use.
• ssh(1), ssh-agent(8): allow the presence of the WAYLAND_DISPLAY environment variable to enable SSH_ASKPASS, similarly to the X11 DISPLAY environment variable. GHPR479

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D48914