OpenSSH 9.0 released

We consider the removal of the need for double-quoting shell characters in file names to be a benefit and do not intend to introduce bug-compatibility for legacy scp/rcp in scp(1) when using the SFTP protocol.

OpenSSH 9.0 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 8.9
=========================

This release is focused on bug fixing.

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

This release switches scp(1) from using the legacy scp/rcp protocol
to using the SFTP protocol 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.

This creates one area of potential incompatibility: scp(1) when using
the SFTP protocol no longer requires this finicky and brittle quoting,
and attempts to use it may cause transfers to fail. We consider the
removal of the need for double-quoting shell characters in file names
to be a benefit and do not intend to introduce bug-compatibility for
legacy scp/rcp in scp(1) when using the SFTP protocol.

Another area of potential incompatibility relates to the use of remote
paths relative to other user's home directories, for example -
"scp host:~user/file /tmp". The SFTP protocol has no native way to
expand a ~user path. However, sftp-server(8) in OpenSSH 8.7 and later
support a protocol extension "[email protected]" to support
this.

In case of incompatibility, the scp(1) client may be instructed to use
the legacy scp/rcp using the -O flag.

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

 * ssh(1), sshd(8): use the hybrid Streamlined NTRU Prime + x25519 key
   exchange method by default ("[email protected]").
   The NTRU algorithm is believed to resist attacks enabled by future
   quantum computers and is paired with the X25519 ECDH key exchange
   (the previous default) as a backstop against any weaknesses in
   NTRU Prime that may be discovered in the future. The combination
   ensures that the hybrid exchange offers at least as good security
   as the status quo.

   We are making this change now (i.e. ahead of cryptographically-
   relevant quantum computers) to prevent "capture now, decrypt
   later" attacks where an adversary who can record and store SSH
   session ciphertext would be able to decrypt it once a sufficiently
   advanced quantum computer is available.

 * sftp-server(8): support the "copy-data" extension to allow server-
   side copying of files/data, following the design in
   draft-ietf-secsh-filexfer-extensions-00. bz2948

 * sftp(1): add a "cp" command to allow the sftp client to perform
   server-side file copies.

Bugfixes
--------

 * ssh(1), sshd(8): upstream: fix poll(2) spin when a channel's output
   fd closes without data in the channel buffer. bz3405 and bz3411

 * sshd(8): pack pollfd array in server listen/accept loop. Could
   cause the server to hang/spin when MaxStartups > RLIMIT_NOFILE

 * ssh-keygen(1): avoid NULL deref via the find-principals and
   check-novalidate operations. bz3409 and GHPR#307 respectively.

 * scp(1): fix a memory leak in argument processing. bz3404

 * sshd(8): don't try to resolve ListenAddress directives in the sshd
   re-exec path. They are unused after re-exec and parsing errors
   (possible for example if the host's network configuration changed)
   could prevent connections from being accepted.
    
 * sshd(8): when refusing a public key authentication request from a
   client for using an unapproved or unsupported signature algorithm
   include the algorithm name in the log message to make debugging
   easier.
    
Portability
-----------

 * sshd(8): refactor platform-specific locked account check, fixing
   an incorrect free() on platforms with both libiaf and shadow
   passwords (probably only Unixware) GHPR#284,

 * ssh(1), sshd(8): Fix possible integer underflow in scan_scaled(3)
   parsing of K/M/G/etc quantities. bz#3401.

 * sshd(8): provide killpg implementation (mostly for Tandem NonStop)
   GHPR#301.

 * Check for missing ftruncate prototype. GHPR#301

 * sshd(8): default to not using sandbox when cross compiling. On most
   systems poll(2) does not work when the number of FDs is reduced
   with setrlimit, so assume it doesn't when cross compiling and we
   can't run the test.  bz#3398.

 * sshd(8): allow ppoll_time64 in seccomp sandbox. Should fix sandbox
   violations on some (at least i386 and armhf) 32bit Linux platforms.
   bz#3396.

 * Improve detection of -fzero-call-used-regs=all support in
   configure script.


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


 - SHA1 (openssh-9.0.tar.gz) = 05302aa4781e1a69db4261474ed940bd685afc24
 - SHA256 (openssh-9.0.tar.gz) = 9I/FrLf5Gij/4NIPts9A8yWVi0ienyyMqjqn8s0hyLk=

 - SHA1 (openssh-9.0p1.tar.gz) = 06dd658874dcd22d66311cf5999bd56c614de509
 - SHA256 (openssh-9.0p1.tar.gz) = A5dDAhYenszjIVPPoQAS8eZcjzdQ9XOnOrG+/Vlyooo=

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

Please note that the OpenPGP key used to sign releases has been
rotated for this release. The new key has been signed by the previous
key to provide continuity.

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

- Please read https://www.openssh.com/report.html
  Security bugs should be reported directly to [email protected]