xref: /freebsd/crypto/openssh/FREEBSD-upgrade (revision d5e2d0f140cef6d09c4ddeb594cee027642366a7)

	    FreeBSD maintainer's guide to OpenSSH-portable
	    ==============================================

    These instructions assume you have a clone of the FreeBSD git repo
    main branch in src/freebsd/main, and will store vendor trees under
    src/freebsd/vendor/.  In addition, this assumes there is a "freebsd"
    origin pointing to git(repo).freebsd.org/src.git.

01) Make sure your mail spool has plenty of free space.  It'll fill up
    pretty fast once you're done with this checklist.

02) Download the latest OpenSSH-portable tarball and signature from
    OpenBSD (https://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/).

03) Verify the signature:

    $ gpg --verify openssh-X.YpZ.tar.gz.asc

04) Unpack the tarball in a suitable directory:

    $ tar xf openssh-X.YpZ.tar.gz

05) Copy to a vendor branch:

    $ cd src/freebsd/main
    $ git worktree add ../vendor/openssh freebsd/vendor/openssh
    $ cd ../vendor/openssh
    $ rsync --archive --delete --exclude=.git /path/to/openssh-X.YpZ/ ./

06) Take care of added / deleted files:

    $ git add -A

07) Commit:

    $ git commit -m "Vendor import of OpenSSH X.YpZ"

08) Tag:

    $ git tag -a -m "Tag OpenSSH X.YpZ" vendor/openssh/X.YpZ

    At this point the vendor branch can be pushed to the FreeBSD repo via:

    $ git push freebsd vendor/openssh
    $ git push freebsd vendor/openssh/X.YpZ

    Note the second "git push" command is used to push the tag, which is
    not pushed by default.

    It is also possible to push the branch and tag together, but use
    --dry-run first to ensure that no undesired tags will be pushed:

    $ git push --dry-run --follow-tags freebsd vendor/openssh
    $ git push --follow-tags freebsd vendor/openssh

    The update and tag could instead be pushed later, along with the merge
    to main, but pushing now allows others to collaborate.

09) Merge from the vendor branch:

    $ git subtree merge -P crypto/openssh vendor/openssh

    A number of files have been deleted from FreeBSD's copy of ssh,
    including rendered man pages (which have a .0 extension).  When
    git prompts for these deleted files during the merge, choose 'd'
    (leaving them deleted).

10) Resolve conflicts.  Remember to bump the version addendum in
    version.h, and update the default value in sshd_config and
    sshd_config.5.

11) Diff against the vendor branch:

    $ git diff --diff-filter=M vendor/openssh/X.YpZ HEAD:crypto/openssh

    Review the diff for any unexpected changes.

12) Run the configure script:

    $ cd crypto/openssh
    $ sh freebsd-configure.sh

13) Review changes to config.h very carefully.

    Note that libwrap should not be defined in config.h; as of
    r311585 (233932cc2a60) it is conditional on MK_TCP_WRAPPERS.

14) If source files have been added or removed, update the appropriate
    makefiles to reflect changes in the vendor's Makefile.in.

15) Update ssh_namespace.h:

    $ cd crypto/openssh
    $ sh freebsd-namespace.sh

16) Build and install world, reboot, test.  Pay particular attention
    to pam_ssh(8), which gropes inside libssh and will break if
    something significant changes or if ssh_namespace.h is out of
    whack.

17) Check for references to obsolete configuration options
    (e.g., ChallengeResponseAuthentication in sshd_config) which
    may exist in release/ scripts.

18) Commit, and hunker down for the inevitable storm of complaints.



	  An overview of FreeBSD changes to OpenSSH-portable
	  ==================================================

1) Modified server-side defaults

   We've modified some configuration defaults in sshd:

      - UsePAM defaults to "yes".
      - PermitRootLogin defaults to "no".
      - PasswordAuthentication defaults to "no".
      - VersionAddendum defaults to "FreeBSD-YYYYMMDD".
      - UseDNS defaults to "yes".

2) Modified client-side defaults

   We defaulted CheckHostIP to "no" in 2000 (a95c1225217b).  Upstream has
   now made the same change, and we no longer have any modified client-side
   defaults.

3) Canonic host names

   We've added code to ssh.c to canonicize the target host name after
   reading options but before trying to connect.  This eliminates the
   usual problem with duplicate known_hosts entries.

   We added this support in 2002 (r99054 / bf2e2524a2ce).  In 2014
   upstream introduced CanonicalDomains and related options to serve a
   similar purpose but they require environment-specific configuration.

4) setusercontext() environment

   Our setusercontext(3) can set environment variables, which we must
   take care to transfer to the child's environment.

5) TCP wrappers

   Support for TCP wrappers was removed in upstream 6.7p1.  We've
   added it back by porting the 6.6p1 code forward.

   TCP wrappers support in sshd will be disabled in HEAD and will
   be removed from FreeBSD in the future.

6) Agent client reference counting

   We've added code to ssh-agent.c to implement client reference
   counting; the agent will automatically exit when the last client
   disconnects.

7) Class-based login restrictions (27ceebbc2402)

   We've added code to auth.c to enforce the host.allow, host.deny,
   times.allow and times.deny login class capabilities, based on an
   upstream submission from
   https://github.com/openssh/openssh-portable/pull/262.

8) Blocklist integration

   We include blocklist (https://github.com/zoulasc/blocklist) in FreeBSD,
   and ssh is patched to report login failures to it.

9) Paths

   A number of paths are changed to match FreeBSD's configuration (e.g.,
   using /usr/local/ instead of /uxr/X11R6/).

10) Memory leaks

   Coverity reported a memory leak for which we proposed a fix in
   https://reviews.freebsd.org/D37253 and sent to the upstream mailing list at
   https://lists.mindrot.org/pipermail/openssh-unix-dev/2022-November/040497.html

   Upstream subsequently fixed only one of the related leaks, so we reverted
   the partial fix and applied our change.

11) Retired patches

   We no longer have HPN patches (adaptive buffer size for increased
   throughput on high-BxD links) or client-side VersionAddendum, but we
   recognize and ignore the configuration options to avoid breaking
   existing configurations.

12) PrintLastLog bugfix

   Upstream's autoconf sets DISABLE_LASTLOG if the system does not have
   lastlog.ll_line, but uses it to disable the PrintLastLog configuration
   option altogether.  There is a hacky SKIP_DISABLE_LASTLOG_DEFINE=yes to
   skip setting DISABLE_LASTLOG which we've applied for FreeBSD, but the
   autoconf machinery really ought to be reworked.  Reported upstream at
   https://lists.mindrot.org/pipermail/openssh-unix-dev/2022-May/040242.html


This port was brought to you by (in no particular order) DARPA, NAI
Labs, ThinkSec, Nescafé, the Aberlour Glenlivet Distillery Co.,
Suzanne Vega, and a Sanford's #69 Deluxe Marker.

					-- des@FreeBSD.org