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Current tag: OPENSSH


Revision 1.1.1.15 / (download) - annotate - [select for diffs] (vendor branch), Wed Oct 25 20:14:32 2023 UTC (5 months, 3 weeks ago) by christos
Branch: OPENSSH
CVS Tags: v96-20231218, v95-20231004
Changes since 1.1.1.14: +36 -40 lines
Diff to previous 1.1.1.14 (colored)

Import OpenSSH 9.5 (Last was OpenSSH 9.3)

OpenSSH 9.5/9.5p1 (2023-10-04)
OpenSSH 9.5 was released on 2023-10-04. It is available from the
mirrors listed at https://www.openssh.com/.
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 9.4
=========================

This release fixes a number of bugs and adds some small features.

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

 * ssh-keygen(1): generate Ed25519 keys by default. Ed25519 public keys
   are very convenient due to their small size. Ed25519 keys are
   specified in RFC 8709 and OpenSSH has supported them since version 6.5
   (January 2014).

 * sshd(8): the Subsystem directive now accurately preserves quoting of
   subsystem commands and arguments. This may change behaviour for exotic
   configurations, but the most common subsystem configuration
   (sftp-server) is unlikely to be affected.

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

 * ssh(1): add keystroke timing obfuscation to the client. This attempts
   to hide inter-keystroke timings by sending interactive traffic at
   fixed intervals (default: every 20ms) when there is only a small
   amount of data being sent. It also sends fake "chaff" keystrokes for
   a random interval after the last real keystroke. These are
   controlled by a new ssh_config ObscureKeystrokeTiming keyword.

 * ssh(1), sshd(8): Introduce a transport-level ping facility. This adds
   a pair of SSH transport protocol messages SSH2_MSG_PING/PONG to
   implement a ping capability. These messages use numbers in the "local
   extensions" number space and are advertised using a "ping@openssh.com"
   ext-info message with a string version number of "0".

 * sshd(8): allow override of Subsystem directives in sshd Match blocks.

Bugfixes
--------

 * scp(1): fix scp in SFTP mode recursive upload and download of
   directories that contain symlinks to other directories. In scp mode,
   the links would be followed, but in SFTP mode they were not. bz3611

 * ssh-keygen(1): handle cr+lf (instead of just cr) line endings in
   sshsig signature files.

 * ssh(1): interactive mode for ControlPersist sessions if they
   originally requested a tty.

 * sshd(8): make PerSourceMaxStartups first-match-wins

 * sshd(8): limit artificial login delay to a reasonable maximum (5s)
   and don't delay at all for the "none" authentication mechanism.cw
    bz3602

 * sshd(8): Log errors in kex_exchange_identification() with level
   verbose instead of error to reduce preauth log spam. All of those
   get logged with a more generic error message by sshpkt_fatal().

 * sshd(8): correct math for ClientAliveInterval that caused the probes
    to be sent less frequently than configured.

 * ssh(1): fix regression in OpenSSH 9.4 (mux.c r1.99) that caused
   multiplexed sessions to ignore SIGINT under some circumstances.

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

 * Avoid clang zero-call-used-regs=all bug on Apple compilers, which
   for some reason have version numbers that do not match the upstream
   clang version numbers. bz#3584

 * Fix configure test for zlib 1.3 and later/development versions. bz3604

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

 - SHA1 (openssh-9.5.tar.gz) = 8a0bd3a91fac338d97d91817af58df731f6509a3
 - SHA256 (openssh-9.5.tar.gz) = sVMxeM3d6g65qBMktJIofxmK4Ipg9dblKif0VnhPeO0=

 - SHA1 (openssh-9.5p1.tar.gz) = 35c16dcc6e7d0a9465faa241476ef24f76b196cc
 - SHA256 (openssh-9.5p1.tar.gz) = 8Cbnt5un+1QPdRgq+W3IqPHbOV+SK7yfbKYDZyaGCGs=

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@openssh.com
OpenSSH 9.4/9.4p1 (2023-08-10)
OpenSSH 9.4 was released on 2023-08-10. It is available from the
mirrors listed at https://www.openssh.com/.
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 9.3p2
===========================

This release fixes a number of bugs and adds some small features.

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

 * This release removes support for older versions of libcrypto.
   OpenSSH now requires LibreSSL >= 3.1.0 or OpenSSL >= 1.1.1.
   Note that these versions are already deprecated by their upstream
   vendors.

 * ssh-agent(1): PKCS#11 modules must now be specified by their full
   paths. Previously dlopen(3) could search for them in system
   library directories.

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

 * ssh(1): allow forwarding Unix Domain sockets via ssh -W.

 * ssh(1): add support for configuration tags to ssh(1).
   This adds a ssh_config(5) "Tag" directive and corresponding
   "Match tag" predicate that may be used to select blocks of
   configuration similar to the pf.conf(5) keywords of the same
   name.

 * ssh(1): add a "match localnetwork" predicate. This allows matching
   on the addresses of available network interfaces and may be used to
   vary the effective client configuration based on network location.

 * ssh(1), sshd(8), ssh-keygen(1): infrastructure support for KRL
   extensions.  This defines wire formats for optional KRL extensions
   and implements parsing of the new submessages. No actual extensions
   are supported at this point.

 * sshd(8): AuthorizedPrincipalsCommand and AuthorizedKeysCommand now
   accept two additional %-expansion sequences: %D which expands to
   the routing domain of the connected session and %C which expands
   to the addresses and port numbers for the source and destination
   of the connection.

 * ssh-keygen(1): increase the default work factor (rounds) for the
   bcrypt KDF used to derive symmetric encryption keys for passphrase
   protected key files by 50%.

Bugfixes
--------

 * ssh-agent(1): improve isolation between loaded PKCS#11 modules
   by running separate ssh-pkcs11-helpers for each loaded provider.

 * ssh(1): make -f (fork after authentication) work correctly with
   multiplexed connections, including ControlPersist. bz3589 bz3589

 * ssh(1): make ConnectTimeout apply to multiplexing sockets and not
   just to network connections.

 * ssh-agent(1), ssh(1): improve defences against invalid PKCS#11
   modules being loaded by checking that the requested module
   contains the required symbol before loading it.

 * sshd(8): fix AuthorizedPrincipalsCommand when AuthorizedKeysCommand
   appears before it in sshd_config. Since OpenSSH 8.7 the
   AuthorizedPrincipalsCommand directive was incorrectly ignored in
   this situation. bz3574

 * sshd(8), ssh(1), ssh-keygen(1): remove vestigal support for KRL
   signatures When the KRL format was originally defined, it included
   support for signing of KRL objects. However, the code to sign KRLs
   and verify KRL signatues was never completed in OpenSSH. This
   release removes the partially-implemented code to verify KRLs.
   All OpenSSH tools now ignore KRL_SECTION_SIGNATURE sections in
   KRL files.

 * All: fix a number of memory leaks and unreachable/harmless integer
   overflows.

 * ssh-agent(1), ssh(1): don't truncate strings logged from PKCS#11
   modules; GHPR406

 * sshd(8), ssh(1): better validate CASignatureAlgorithms in
   ssh_config and sshd_config. Previously this directive would accept
   certificate algorithm names, but these were unusable in practice as
   OpenSSH does not support CA chains. bz3577

 * ssh(1): make `ssh -Q CASignatureAlgorithms` only list signature
   algorithms that are valid for CA signing. Previous behaviour was
   to list all signing algorithms, including certificate algorithms.

 * ssh-keyscan(1): gracefully handle systems where rlimits or the
   maximum number of open files is larger than INT_MAX; bz3581

 * ssh-keygen(1): fix "no comment" not showing on when running
   `ssh-keygen -l` on multiple keys where one has a comment and other
   following keys do not. bz3580

 * scp(1), sftp(1): adjust ftruncate() logic to handle servers that
   reorder requests. Previously, if the server reordered requests then
   the resultant file would be erroneously truncated.

 * ssh(1): don't incorrectly disable hostname canonicalization when
   CanonicalizeHostname=yes and ProxyJump was expicitly set to
   "none". bz3567

 * scp(1): when copying local->remote, check that the source file
   exists before opening an SFTP connection to the server. Based on
   GHPR#370

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

 * All: a number of build fixes for various platforms and
   configuration combinations.

 * sshd(8): provide a replacement for the SELinux matchpathcon()
   function, which is deprecated.

 * All: relax libcrypto version checks for OpenSSL >=3. Beyond
   OpenSSL 3.0, the ABI compatibility guarantees are wider (only
   the library major must match instead of major and minor in
   earlier versions).  bz#3548.

 * Tests: fix build problems for the sk-dummy.so FIDO provider module
   used in some tests.

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

 - SHA1 (openssh-9.4.tar.gz) = d88126d8d7b8e5bf4656587ac4a16055560641cc
 - SHA256 (openssh-9.4.tar.gz) = 7eqFjx2hAunw+1Jy7f1JQXq//3AMr9B3dKtASDtq8go=

 - SHA1 (openssh-9.4p1.tar.gz) = 5dea1f3c88f9cfe53a711a3c893ee8b7d3ffecff
 - SHA256 (openssh-9.4p1.tar.gz) = Ngj9kIjbIWPOs+YAyFq3nQ3j0iHlkZLqGSPiMmOGaoU=

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@openssh.com

Revision 1.1.1.14 / (download) - annotate - [select for diffs] (vendor branch), Wed Oct 5 22:35:33 2022 UTC (18 months, 1 week ago) by christos
Branch: OPENSSH
CVS Tags: v93p2-20230719, v93-20230719, v91-20221004
Changes since 1.1.1.13: +18 -8 lines
Diff to previous 1.1.1.13 (colored)

Import OpenSSH-9.1 (previously we were on OpenSSH-9.0)

This release is focused on bug fixing.

Security
========

This release contains fixes for three minor memory safety problems.
None are believed to be exploitable, but we report most memory safety
problems as potential security vulnerabilities out of caution.

 * ssh-keyscan(1): fix a one-byte overflow in SSH- banner processing.
   Reported by Qualys

 * ssh-keygen(1): double free() in error path of file hashing step in
   signing/verify code; GHPR333

 * ssh-keysign(8): double-free in error path introduced in openssh-8.9

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

 * The portable OpenSSH project now signs commits and release tags
   using git's recent SSH signature support. The list of developer
   signing keys is included in the repository as .git_allowed_signers
   and is cross-signed using the PGP key that is still used to sign
   release artifacts:
   https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/RELEASE_KEY.asc

 * 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).

   ssh(1) will terminate a connection if the server offers an RSA key
   that falls below this limit, as the SSH protocol does not include
   the ability to retry a failed key exchange.

 * 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

Bugfixes
--------

 * ssh-keygen(1): implement the "verify-required" certificate option.
   This was already documented when support for user-verified FIDO
   keys was added, but the ssh-keygen(1) code was missing.

 * ssh-agent(1): hook up the restrict_websafe command-line flag;
   previously the flag was accepted but never actually used.

 * sftp(1): improve filename tab completions: never try to complete
   names to non-existent commands, and better match the completion
   type (local or remote filename) against the argument position
   being completed.

 * ssh-keygen(1), ssh(1), ssh-agent(1): several fixes to FIDO key
   handling, especially relating to keys that request
   user-verification. These should reduce the number of unnecessary
   PIN prompts for keys that support intrinsic user verification.
   GHPR302, GHPR329

 * ssh-keygen(1): when enrolling a FIDO resident key, check if a
   credential with matching application and user ID strings already
   exists and, if so, prompt the user for confirmation before
   overwriting the credential. GHPR329

 * sshd(8): improve logging of errors when opening authorized_keys
   files. bz2042

 * ssh(1): avoid multiplexing operations that could cause SIGPIPE from
   causing the client to exit early. bz3454

 * ssh_config(5), sshd_config(5): clarify that the RekeyLimit
   directive applies to both transmitted and received data. GHPR328

 * ssh-keygen(1): avoid double fclose() in error path.

 * sshd(8): log an error if pipe() fails while accepting a
   connection. bz3447

 * ssh(1), ssh-keygen(1): fix possible NULL deref when built without
   FIDO support. bz3443

 * ssh-keyscan(1): add missing *-sk types to ssh-keyscan manpage.
   GHPR294.

 * sshd(8): ensure that authentication passwords are cleared from
   memory in error paths. GHPR286

 * ssh(1), ssh-agent(1): avoid possibility of notifier code executing
   kill(-1). GHPR286

 * ssh_config(5): note that the ProxyJump directive also accepts the
   same tokens as ProxyCommand. GHPR305.

 * scp(1): do not not ftruncate(3) files early when in sftp mode. The
   previous behaviour of unconditionally truncating the destination
   file would cause "scp ~/foo localhost:foo" and the reverse
   "scp localhost:foo ~/foo" to delete all the contents of their
   destination. bz3431

 * ssh-keygen(1): improve error message when 'ssh-keygen -Y sign' is
   unable to load a private key; bz3429

 * sftp(1), scp(1): when performing operations that glob(3) a remote
   path, ensure that the implicit working directory used to construct
   that path escapes glob(3) characters. This prevents glob characters
   from being processed in places they shouldn't, e.g. "cd /tmp/a*/",
   "get *.txt" should have the get operation treat the path "/tmp/a*"
   literally and not attempt to expand it.

 * ssh(1), sshd(8): be stricter in which characters will be accepted
   in specifying a mask length; allow only 0-9. GHPR278

 * ssh-keygen(1): avoid printing hash algorithm twice when dumping a
   KRL

 * ssh(1), sshd(8): continue running local I/O for open channels
   during SSH transport rekeying. This should make ~-escapes work in
   the client (e.g. to exit) if the connection happened to have
   stalled during a rekey event.

 * ssh(1), sshd(8): avoid potential poll() spin during rekeying

 * Further hardening for sshbuf internals: disallow "reparenting" a
   hierarchical sshbuf and zero the entire buffer if reallocation
   fails. GHPR287

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

 * ssh(1), ssh-keygen(1), sshd(8): automatically enable the built-in
   FIDO security key support if libfido2 is found and usable, unless
   --without-security-key-builtin was requested.

 * ssh(1), ssh-keygen(1), sshd(8): many fixes to make the WinHello
   FIDO device usable on Cygwin. The windows://hello FIDO device will
   be automatically used by default on this platform unless requested
   otherwise, or when probing resident FIDO credentials (an operation
   not currently supported by WinHello).

 * Portable OpenSSH: remove workarounds for obsolete and unsupported
   versions of OpenSSL libcrypto. In particular, this release removes
   fallback support for OpenSSL that lacks AES-CTR or AES-GCM.

   Those AES cipher modes were added to OpenSSL prior to the minimum
   version currently supported by OpenSSH, so this is not expected to
   impact any currently supported configurations.

 * sshd(8): fix SANDBOX_SECCOMP_FILTER_DEBUG on current Linux/glibc

 * All: resync and clean up internal CSPRNG code.

 * scp(1), sftp(1), sftp-server(8): avoid linking these programs with
   unnecessary libraries. They are no longer linked against libz and
   libcrypto. This may be of benefit to space constrained systems
   using any of those components in isolation.

 * sshd(8): add AUDIT_ARCH_PPC to supported seccomp sandbox
   architectures.

 * configure: remove special casing of crypt(). configure will no
   longer search for crypt() in libcrypto, as it was removed from
   there years ago. configure will now only search libc and libcrypt.

 * configure: refuse to use OpenSSL 3.0.4 due to potential RCE in its
   RSA implementation (CVE-2022-2274) on x86_64.

 * All: request 1.1x API compatibility for OpenSSL >=3.x; GHPR322

 * ssh(1), ssh-keygen(1), sshd(8): fix a number of missing includes
   required by the XMSS code on some platforms.

 * sshd(8): cache timezone data in capsicum sandbox.

Revision 1.1.1.13 / (download) - annotate - [select for diffs] (vendor branch), Fri Apr 15 13:58:18 2022 UTC (2 years ago) by christos
Branch: OPENSSH
CVS Tags: v90-20220408
Changes since 1.1.1.12: +4 -1 lines
Diff to previous 1.1.1.12 (colored)

Import OpenSSH-9.0

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 "expand-path@openssh.com" 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 ("sntrup761x25519-sha512@openssh.com").
   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 GHPR307 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) GHPR284,

 * 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)
   GHPR301.

 * Check for missing ftruncate prototype. GHPR301

 * 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.

Revision 1.1.1.12 / (download) - annotate - [select for diffs] (vendor branch), Wed Feb 23 19:04:26 2022 UTC (2 years, 1 month ago) by christos
Branch: OPENSSH
CVS Tags: v89-20220223
Changes since 1.1.1.11: +2 -2 lines
Diff to previous 1.1.1.11 (colored)

Import OpenSSH 8.9.

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.

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 "expand-path@openssh.com" to support
this.

Security Near Miss
==================

 * sshd(8): fix an integer overflow in the user authentication path
   that, in conjunction with other logic errors, could have yielded
   unauthenticated access under difficult to exploit conditions.

   This situation is not exploitable because of independent checks in
   the privilege separation monitor. Privilege separation has been
   enabled by default in since openssh-3.2.2 (released in 2002) and
   has been mandatory since openssh-7.5 (released in 2017). Moreover,
   portable OpenSSH has used toolchain features available in most
   modern compilers to abort on signed integer overflow since
   openssh-6.5 (released in 2014).

   Thanks to Malcolm Stagg for finding and reporting this bug.

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

 * 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.

 * This release modifies the FIDO security key middleware interface
   and increments SSH_SK_VERSION_MAJOR.

Changes since OpenSSH 8.8
=========================

This release includes a number of new features.

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

 * 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)
   A detailed description of the feature is available at
   https://www.openssh.com/agent-restrict.html and the protocol
   extensions are documented in the PROTOCOL and PROTOCOL.agent
   files in the source release.

 * 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.

 * ssh-keygen(1): when downloading resident keys from a FIDO token,
   pass back the user ID that was used when the key was created and
   append it to the filename the key is written to (if it is not the
   default). Avoids keys being clobbered if the user created multiple
   resident keys with the same application string but different user
   IDs.

 * ssh-keygen(1), ssh(1), ssh-agent(1): better handling for FIDO keys
   on tokens that provide user verification (UV) on the device itself,
   including biometric keys, avoiding unnecessary PIN prompts.

 * ssh-keygen(1): add "ssh-keygen -Y match-principals" operation to
   perform matching of principals names against an allowed signers
   file. To be used towards a TOFU model for SSH signatures in git.

 * ssh-add(1), ssh-agent(1): allow pin-required FIDO keys to be added
   to ssh-agent(1). $SSH_ASKPASS will be used to request the PIN at
   authentication time.

 * ssh-keygen(1): allow selection of hash at sshsig signing time
   (either sha512 (default) or sha256).

 * ssh(1), sshd(8): read network data directly to the packet input
   buffer instead indirectly via a small stack buffer. Provides a
   modest performance improvement.

 * ssh(1), sshd(8): read data directly to the channel input buffer,
   providing a similar modest performance improvement.

 * ssh(1): extend the PubkeyAuthentication configuration directive to
   accept yes|no|unbound|host-bound to allow control over one of the
   protocol extensions used to implement agent-restricted keys.

Bugfixes
--------

 * sshd(8): document that CASignatureAlgorithms, ExposeAuthInfo and
   PubkeyAuthOptions can be used in a Match block. PR#277.

 * sshd(8): fix possible string truncation when constructing paths to
   .rhosts/.shosts files with very long user home directory names.

 * ssh-keysign(1): unbreak for KEX algorithms that use SHA384/512
   exchange hashes

 * ssh(1): don't put the TTY into raw mode when SessionType=none,
   avoids ^C being unable to kill such a session. bz3360

 * scp(1): fix some corner-case bugs in SFTP-mode handling of
   ~-prefixed paths.

 * ssh(1): unbreak hostbased auth using RSA keys. Allow ssh(1) to
   select RSA keys when only RSA/SHA2 signature algorithms are
   configured (this is the default case). Previously RSA keys were
   not being considered in the default case.

 * ssh-keysign(1): make ssh-keysign use the requested signature
   algorithm and not the default for the key type. Part of unbreaking
   hostbased auth for RSA/SHA2 keys.

 * ssh(1): stricter UpdateHostkey signature verification logic on
   the client- side. Require RSA/SHA2 signatures for RSA hostkeys
   except when RSA/SHA1 was explicitly negotiated during initial
   KEX; bz3375

 * ssh(1), sshd(8): fix signature algorithm selection logic for
   UpdateHostkeys on the server side. The previous code tried to
   prefer RSA/SHA2 for hostkey proofs of RSA keys, but missed some
   cases. This will use RSA/SHA2 signatures for RSA keys if the
   client proposed these algorithms in initial KEX. bz3375

 * All: convert all uses of select(2)/pselect(2) to poll(2)/ppoll(2).
   This includes the mainloops in ssh(1), ssh-agent(1), ssh-agent(1)
   and sftp-server(8), as well as the sshd(8) listen loop and all
   other FD read/writability checks. On platforms with missing or
   broken poll(2)/ppoll(2) syscalls a select(2)-based compat shim is
   available.

 * ssh-keygen(1): the "-Y find-principals" command was verifying key
   validity when using ca certs but not with simple key lifetimes
   within the allowed signers file.

 * ssh-keygen(1): make sshsig verify-time argument parsing optional

 * sshd(8): fix truncation in rhosts/shosts path construction.

 * ssh(1), ssh-agent(1): avoid xmalloc(0) for PKCS#11 keyid for ECDSA
   keys (we already did this for RSA keys). Avoids fatal errors for
   PKCS#11 libraries that return empty keyid, e.g. Microchip ATECC608B
   "cryptoauthlib"; bz#3364

 * ssh(1), ssh-agent(1): improve the testing of credentials against
   inserted FIDO: ask the token whether a particular key belongs to
   it in cases where the token supports on-token user-verification
   (e.g. biometrics) rather than just assuming that it will accept it.

   Will reduce spurious "Confirm user presence" notifications for key
   handles that relate to FIDO keys that are not currently inserted in at
   least some cases. bz3366

 * ssh(1), sshd(8): correct value for IPTOS_DSCP_LE. It needs to
   allow for the preceding two ECN bits. bz#3373

 * ssh-keygen(1): add missing -O option to usage() for the "-Y sign"
   option.

 * ssh-keygen(1): fix a NULL deref when using the find-principals
   function, when matching an allowed_signers line that contains a
   namespace restriction, but no restriction specified on the
   command-line

 * ssh-agent(1): fix memleak in process_extension(); oss-fuzz
   issue #42719

 * ssh(1): suppress "Connection to xxx closed" messages when LogLevel
   is set to "error" or above. bz3378

 * ssh(1), sshd(8): use correct zlib flags when inflate(3)-ing
   compressed packet data. bz3372

 * scp(1): when recursively transferring files in SFTP mode, create the
   destination directory if it doesn't already exist to match scp(1) in
   legacy RCP mode behaviour.

 * scp(1): many improvements in error message consistency between scp(1)
   in SFTP mode vs legacy RCP mode.

 * sshd(8): fix potential race in SIGTERM handling PR#289

 * ssh(1), ssh(8): since DSA keys are deprecated, move them to the
   end of the default list of public keys so that they will be tried
   last. PR#295

 * ssh-keygen(1): allow 'ssh-keygen -Y find-principals' to match
   wildcard principals in allowed_signers files

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

 * ssh(1), sshd(8): don't trust closefrom(2) on Linux. glibc's
   implementation does not work in a chroot when the kernel does not
   have close_range(2). It tries to read from /proc/self/fd and when
   that fails dies with an assertion of sorts. Instead, call
   close_range(2) directly from our compat code and fall back if
   that fails.  bz#3349,

 * OS X poll(2) is broken; use compat replacement. For character-
   special devices like /dev/null, Darwin's poll(2) returns POLLNVAL
   when polled with POLLIN. Apparently this is Apple bug 3710161 -
   not public but a websearch will find other OSS projects
   rediscovering it periodically since it was first identified in
   2005.

 * Correct handling of exceptfds/POLLPRI in our select(2)-based
   poll(2)/ppoll(2) compat implementation.

 * Cygwin: correct checking of mbstowcs() return value.

 * Add a basic SECURITY.md that refers people to the openssh.com
   website.

 * Enable additional compiler warnings and toolchain hardening flags,
   including -Wbitwise-instead-of-logical, -Wmisleading-indentation,
   -fzero-call-used-regs and -ftrivial-auto-var-init.

 * HP/UX. Use compat getline(3) on HP-UX 10.x, where the libc version
   is not reliable.

Revision 1.1.1.11 / (download) - annotate - [select for diffs] (vendor branch), Thu Sep 2 11:22:30 2021 UTC (2 years, 7 months ago) by christos
Branch: OPENSSH
CVS Tags: v88-20210926, v87-20210820
Changes since 1.1.1.10: +33 -4 lines
Diff to previous 1.1.1.10 (colored)

Import OpenSSH-8.7:

Imminent deprecation notice
===========================

OpenSSH will disable the ssh-rsa signature scheme by default in the
next release.

In the SSH protocol, the "ssh-rsa" signature scheme uses the SHA-1
hash algorithm in conjunction with the RSA public key algorithm.
It is now possible[1] to perform chosen-prefix attacks against the
SHA-1 algorithm for less than USD$50K.

Note that the deactivation of "ssh-rsa" signatures does not necessarily
require cessation of use for RSA keys. In the SSH protocol, keys may be
capable of signing using multiple algorithms. In particular, "ssh-rsa"
keys are capable of signing using "rsa-sha2-256" (RSA/SHA256),
"rsa-sha2-512" (RSA/SHA512) and "ssh-rsa" (RSA/SHA1). Only the last of
these is being turned off by default.

This algorithm is unfortunately still used widely despite the
existence of better alternatives, being the only remaining public key
signature algorithm specified by the original SSH RFCs that is still
enabled by default.

The better alternatives include:

 * The RFC8332 RSA SHA-2 signature algorithms rsa-sha2-256/512. These
   algorithms have the advantage of using the same key type as
   "ssh-rsa" but use the safe SHA-2 hash algorithms. These have been
   supported since OpenSSH 7.2 and are already used by default if the
   client and server support them.

 * The RFC8709 ssh-ed25519 signature algorithm. It has been supported
   in OpenSSH since release 6.5.

 * The RFC5656 ECDSA algorithms: ecdsa-sha2-nistp256/384/521. These
   have been supported by OpenSSH since release 5.7.

To check whether a server is using the weak ssh-rsa public key
algorithm, for host authentication, try to connect to it after
removing the ssh-rsa algorithm from ssh(1)'s allowed list:

    ssh -oHostKeyAlgorithms=-ssh-rsa user@host

If the host key verification fails and no other supported host key
types are available, the server software on that host should be
upgraded.

OpenSSH recently enabled the UpdateHostKeys option by default to
assist the client by automatically migrating to better algorithms.

[1] "SHA-1 is a Shambles: First Chosen-Prefix Collision on SHA-1 and
    Application to the PGP Web of Trust" Leurent, G and Peyrin, T
    (2020) https://eprint.iacr.org/2020/014.pdf

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

This release includes a number of changes that may affect existing
configurations:

 * scp(1): this release changes the behaviour of remote to remote
   copies (e.g. "scp host-a:/path host-b:") to transfer through the
   local host by default. This was previously available via the -3
   flag. This mode avoids the need to expose credentials on the
   origin hop, avoids triplicate interpretation of filenames by the
   shell (by the local system, the copy origin and the destination)
   and, in conjunction with the SFTP support for scp(1) mentioned
   below, allows use of all authentication methods to the remote
   hosts (previously, only non-interactive methods could be used).
   A -R flag has been added to select the old behaviour.

 * ssh(1)/sshd(8): both the client and server are now using a
   stricter configuration file parser. The new parser uses more
   shell-like rules for quotes, space and escape characters. It is
   also more strict in rejecting configurations that include options
   lacking arguments. Previously some options (e.g. DenyUsers) could
   appear on a line with no subsequent arguments. This release will
   reject such configurations. The new parser will also reject
   configurations with unterminated quotes and multiple '='
   characters after the option name.

 * ssh(1): when using SSHFP DNS records for host key verification,
   ssh(1) will verify all matching records instead of just those
   with the specific signature type requested. This may cause host
   key verification problems if stale SSHFP records of a different
   or legacy signature type exist alongside other records for a
   particular host. bz#3322

 * ssh-keygen(1): when generating a FIDO key and specifying an
   explicit attestation challenge (using -Ochallenge), the challenge
   will now be hashed by the builtin security key middleware. This
   removes the (undocumented) requirement that challenges be exactly
   32 bytes in length and matches the expectations of libfido2.

 * sshd(8): environment="..." directives in authorized_keys files are
   now first-match-wins and limited to 1024 discrete environment
   variable names.

Changes since OpenSSH 8.6
=========================

This release contains a mix of new features and bug-fixes.

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

 - scp(1): experimental support for transfers using the SFTP protocol
   as a replacement for the venerable SCP/RCP protocol that it has
   traditionally used. SFTP offers more predictable filename handling
   and does not require expansion of glob(3) patterns via the shell
   on the remote side.

   SFTP support may be enabled via a temporary scp -s flag. It is
   intended for SFTP to become the default transfer mode in the
   near future, at which time the -s flag will be removed. The -O
   flag exists to force use of the original SCP/RCP protocol for
   cases where SFTP may be unavailable or incompatible.

 - sftp-server(8): add a protocol extension to support expansion of
   ~/ and ~user/ prefixed paths. This was added to support these
   paths when used by scp(1) while in SFTP mode.

 - ssh(1): add a ForkAfterAuthentication ssh_config(5) counterpart to
   the ssh(1) -f flag. GHPR#231

 - ssh(1): add a StdinNull directive to ssh_config(5) that allows the
   config file to do the same thing as -n does on the ssh(1) command-
   line. GHPR#231

 - ssh(1): add a SessionType directive to ssh_config, allowing the
    configuration file to offer equivalent control to the -N (no
    session) and -s (subsystem) command-line flags. GHPR#231

 - ssh-keygen(1): allowed signers files used by ssh-keygen(1)
   signatures now support listing key validity intervals alongside
   they key, and ssh-keygen(1) can optionally check during signature
   verification whether a specified time falls inside this interval.
   This feature is intended for use by git to support signing and
   verifying objects using ssh keys.

 - ssh-keygen(8): support printing of the full public key in a sshsig
   signature via a -Oprint-pubkey flag.

Bugfixes
--------

 * ssh(1)/sshd(8): start time-based re-keying exactly on schedule in
   the client and server mainloops. Previously the re-key timeout
   could expire but re-keying would not start until a packet was sent
   or received, causing a spin in select() if the connection was
   quiescent.

 * ssh-keygen(1): avoid Y2038 problem in printing certificate
   validity lifetimes. Dates past 2^31-1 seconds since epoch were
   displayed incorrectly on some platforms. bz#3329

 * scp(1): allow spaces to appear in usernames for local to remote
   and scp -3 remote to remote copies. bz#1164

 * ssh(1)/sshd(8): remove references to ChallengeResponseAuthentication
   in favour of KbdInteractiveAuthentication. The former is what was in
   SSHv1, the latter is what is in SSHv2 (RFC4256) and they were
   treated as somewhat but not entirely equivalent. We retain the old
   name as a deprecated alias so configuration files continue to work
   as well as a reference in the man page for people looking for it.
   bz#3303

 * ssh(1)/ssh-add(1)/ssh-keygen(1): fix decoding of X.509 subject name
   when extracting a key from a PKCS#11 certificate. bz#3327

 * ssh(1): restore blocking status on stdio fds before close. ssh(1)
   needs file descriptors in non-blocking mode to operate but it was
   not restoring the original state on exit. This could cause
   problems with fds shared with other programs via the shell,
   bz#3280 and GHPR#246

 * ssh(1)/sshd(8): switch both client and server mainloops from
   select(3) to pselect(3). Avoids race conditions where a signal
   may arrive immediately before select(3) and not be processed until
   an event fires. bz#2158

 * ssh(1): sessions started with ControlPersist were incorrectly
   executing a shell when the -N (no shell) option was specified.
   bz#3290

 * ssh(1): check if IPQoS or TunnelDevice are already set before
   overriding. Prevents values in config files from overriding values
   supplied on the command line. bz#3319

 * ssh(1): fix debug message when finding a private key to match a
   certificate being attempted for user authentication. Previously it
   would print the certificate's path, whereas it was supposed to be
   showing the private key's path. GHPR#247

 * sshd(8): match host certificates against host public keys, not
   private keys. Allows use of certificates with private keys held in
   a ssh-agent.  bz#3524

 * ssh(1): add a workaround for a bug in OpenSSH 7.4 sshd(8), which
   allows RSA/SHA2 signatures for public key authentication but fails
   to advertise this correctly via SSH2_MSG_EXT_INFO. This causes
   clients of these server to incorrectly match
   PubkeyAcceptedAlgorithmse and potentially refuse to offer valid
   keys. bz#3213

 * sftp(1)/scp(1): degrade gracefully if a sftp-server offers the
   limits@openssh.com extension but fails when the client tries to
   invoke it. bz#3318

 * ssh(1): allow ssh_config SetEnv to override $TERM, which is
   otherwise handled specially by the protocol. Useful in ~/.ssh/config
   to set TERM to something generic (e.g. "xterm" instead of
   "xterm-256color") for destinations that lack terminfo entries.

 * sftp-server(8): the limits@openssh.com extension was incorrectly
   marked as an operation that writes to the filesystem, which made it
   unavailable in sftp-server read-only mode. bz#3318

 * ssh(1): fix SEGV in UpdateHostkeys debug() message, triggered when
   the update removed more host keys than remain present.

 * many manual page fixes.

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

 * ssh(1): move closefrom() to before first malloc. When built against
   tcmalloc, the closefrom() would stomp on file descriptors created
   for tcmalloc's internal use. bz#3321

 * sshd(8): handle GIDs > 2^31 in getgrouplist. When compiled in 32bit
   mode, the getgrouplist implementation may fail for GIDs greater than
   LONG_MAX.

 * ssh(1): xstrdup environment variable used by ForwardAgent. bz#3328

 * sshd(8): don't sigdie() in signal handler in privsep child process;
   this can end up causing sandbox violations per bz3286

Revision 1.1.1.10 / (download) - annotate - [select for diffs] (vendor branch), Mon Apr 19 14:38:29 2021 UTC (2 years, 11 months ago) by christos
Branch: OPENSSH
CVS Tags: v86-20210419
Changes since 1.1.1.9: +12 -1 lines
Diff to previous 1.1.1.9 (colored)

Import OpenSSH-8.6:

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

It is now possible[1] to perform chosen-prefix attacks against the
SHA-1 algorithm for less than USD$50K.

In the SSH protocol, the "ssh-rsa" signature scheme uses the SHA-1
hash algorithm in conjunction with the RSA public key algorithm.
OpenSSH will disable this signature scheme by default in the near
future.

Note that the deactivation of "ssh-rsa" signatures does not necessarily
require cessation of use for RSA keys. In the SSH protocol, keys may be
capable of signing using multiple algorithms. In particular, "ssh-rsa"
keys are capable of signing using "rsa-sha2-256" (RSA/SHA256),
"rsa-sha2-512" (RSA/SHA512) and "ssh-rsa" (RSA/SHA1). Only the last of
these is being turned off by default.

This algorithm is unfortunately still used widely despite the
existence of better alternatives, being the only remaining public key
signature algorithm specified by the original SSH RFCs that is still
enabled by default.

The better alternatives include:

 * The RFC8332 RSA SHA-2 signature algorithms rsa-sha2-256/512. These
   algorithms have the advantage of using the same key type as
   "ssh-rsa" but use the safe SHA-2 hash algorithms. These have been
   supported since OpenSSH 7.2 and are already used by default if the
   client and server support them.

 * The RFC8709 ssh-ed25519 signature algorithm. It has been supported
   in OpenSSH since release 6.5.

 * The RFC5656 ECDSA algorithms: ecdsa-sha2-nistp256/384/521. These
   have been supported by OpenSSH since release 5.7.

To check whether a server is using the weak ssh-rsa public key
algorithm, for host authentication, try to connect to it after
removing the ssh-rsa algorithm from ssh(1)'s allowed list:

    ssh -oHostKeyAlgorithms=-ssh-rsa user@host

If the host key verification fails and no other supported host key
types are available, the server software on that host should be
upgraded.

OpenSSH recently enabled the UpdateHostKeys option by default to assist
the client by automatically migrating to better algorithms.

[1] "SHA-1 is a Shambles: First Chosen-Prefix Collision on SHA-1 and
    Application to the PGP Web of Trust" Leurent, G and Peyrin, T
    (2020) https://eprint.iacr.org/2020/014.pdf

Security
========

 * sshd(8): OpenSSH 8.5 introduced the LogVerbose keyword. When this
   option was enabled with a set of patterns that activated logging
   in code that runs in the low-privilege sandboxed sshd process, the
   log messages were constructed in such a way that printf(3) format
   strings could effectively be specified the low-privilege code.

   An attacker who had sucessfully exploited the low-privilege
   process could use this to escape OpenSSH's sandboxing and attack
   the high-privilege process. Exploitation of this weakness is
   highly unlikely in practice as the LogVerbose option is not
   enabled by default and is typically only used for debugging. No
   vulnerabilities in the low-privilege process are currently known
   to exist.

   Thanks to Ilja Van Sprundel for reporting this bug.

Changes since OpenSSH 8.5
=========================

This release contains mostly bug fixes.

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

 * sftp-server(8): add a new limits@openssh.com protocol extension
   that allows a client to discover various server limits, including
   maximum packet size and maximum read/write length.

 * sftp(1): use the new limits@openssh.com extension (when available)
   to select better transfer lengths in the client.

 * sshd(8): Add ModuliFile keyword to sshd_config to specify the
   location of the "moduli" file containing the groups for DH-GEX.

 * unit tests: Add a TEST_SSH_ELAPSED_TIMES environment variable to
   enable printing of the elapsed time in seconds of each test.

Bugfixes
--------

 * ssh_config(5), sshd_config(5): sync CASignatureAlgorithms lists in
   manual pages with the current default. GHPR#174

 * ssh(1): ensure that pkcs11_del_provider() is called before exit.
   GHPR#234

 * ssh(1), sshd(8): fix problems in string->argv conversion. Multiple
   backslashes were not being dequoted correctly and quoted space in
   the middle of a string was being incorrectly split. GHPR#223

 * ssh(1): return non-zero exit status when killed by signal; bz#3281

 * sftp-server(8): increase maximum SSH2_FXP_READ to match the maximum
   packet size. Also handle zero-length reads that are not explicitly
   banned by the spec.

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

 * sshd(8): don't mistakenly exit on transient read errors on the
   network socket (e.g. EINTR, EAGAIN); bz3297

 * Create a dedicated contrib/gnome-ssk-askpass3.c source instead of
   building it from the same file as used for GNOME2. Use the GNOME3
   gdk_seat_grab() to manage keyboard/mouse/server grabs for better
   compatibility with Wayland.

 * Fix portability build errors bz3293 bz3292 bz3291 bz3278

 * sshd(8): soft-disallow the fstatat64 syscall in the Linux
   seccomp-bpf sandbox. bz3276

 * unit tests: enable autoopt and misc unit tests that were
   previously skipped

Revision 1.1.1.9 / (download) - annotate - [select for diffs] (vendor branch), Fri Mar 5 17:45:26 2021 UTC (3 years, 1 month ago) by christos
Branch: OPENSSH
CVS Tags: v85_20210303
Changes since 1.1.1.8: +14 -1 lines
Diff to previous 1.1.1.8 (colored)

OpenSSH 8.5/8.5p1 (2021-03-03)

OpenSSH 8.5 was released on 2021-03-03. It is available from the
mirrors listed at https://www.openssh.com/.
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

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

It is now possible[1] to perform chosen-prefix attacks against the
SHA-1 algorithm for less than USD$50K.

In the SSH protocol, the "ssh-rsa" signature scheme uses the SHA-1
hash algorithm in conjunction with the RSA public key algorithm.
OpenSSH will disable this signature scheme by default in the near
future.

Note that the deactivation of "ssh-rsa" signatures does not necessarily
require cessation of use for RSA keys. In the SSH protocol, keys may be
capable of signing using multiple algorithms. In particular, "ssh-rsa"
keys are capable of signing using "rsa-sha2-256" (RSA/SHA256),
"rsa-sha2-512" (RSA/SHA512) and "ssh-rsa" (RSA/SHA1). Only the last of
these is being turned off by default.

This algorithm is unfortunately still used widely despite the
existence of better alternatives, being the only remaining public key
signature algorithm specified by the original SSH RFCs that is still
enabled by default.

The better alternatives include:

 * The RFC8332 RSA SHA-2 signature algorithms rsa-sha2-256/512. These
   algorithms have the advantage of using the same key type as
   "ssh-rsa" but use the safe SHA-2 hash algorithms. These have been
   supported since OpenSSH 7.2 and are already used by default if the
   client and server support them.

 * The RFC8709 ssh-ed25519 signature algorithm. It has been supported
   in OpenSSH since release 6.5.

 * The RFC5656 ECDSA algorithms: ecdsa-sha2-nistp256/384/521. These
   have been supported by OpenSSH since release 5.7.

To check whether a server is using the weak ssh-rsa public key
algorithm, for host authentication, try to connect to it after
removing the ssh-rsa algorithm from ssh(1)'s allowed list:

    ssh -oHostKeyAlgorithms=-ssh-rsa user@host

If the host key verification fails and no other supported host key
types are available, the server software on that host should be
upgraded.

This release enables the UpdateHostKeys option by default to assist
the client by automatically migrating to better algorithms.

[1] "SHA-1 is a Shambles: First Chosen-Prefix Collision on SHA-1 and
    Application to the PGP Web of Trust" Leurent, G and Peyrin, T
    (2020) https://eprint.iacr.org/2020/014.pdf

Security
========

 * ssh-agent(1): fixed a double-free memory corruption that was
   introduced in OpenSSH 8.2 . We treat all such memory faults as
   potentially exploitable. This bug could be reached by an attacker
   with access to the agent socket.

   On modern operating systems where the OS can provide information
   about the user identity connected to a socket, OpenSSH ssh-agent
   and sshd limit agent socket access only to the originating user
   and root. Additional mitigation may be afforded by the system's
   malloc(3)/free(3) implementation, if it detects double-free
   conditions.

   The most likely scenario for exploitation is a user forwarding an
   agent either to an account shared with a malicious user or to a
   host with an attacker holding root access.

 * Portable sshd(8): Prevent excessively long username going to PAM.
   This is a mitigation for a buffer overflow in Solaris' PAM username
   handling (CVE-2020-14871), and is only enabled for Sun-derived PAM
   implementations.  This is not a problem in sshd itself, it only
   prevents sshd from being used as a vector to attack Solaris' PAM.
   It does not prevent the bug in PAM from being exploited via some
   other PAM application. GHPR212


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

This release includes a number of changes that may affect existing
configurations:

 * ssh(1), sshd(8): this release changes the first-preference signature
   algorithm from ECDSA to ED25519.

 * ssh(1), sshd(8): set the TOS/DSCP specified in the configuration
   for interactive use prior to TCP connect. The connection phase of
   the SSH session is time-sensitive and often explicitly interactive.
   The ultimate interactive/bulk TOS/DSCP will be set after
   authentication completes.

 * ssh(1), sshd(8): remove the pre-standardization cipher
   rijndael-cbc@lysator.liu.se. It is an alias for aes256-cbc before
   it was standardized in RFC4253 (2006), has been deprecated and
   disabled by default since OpenSSH 7.2 (2016) and was only briefly
   documented in ssh.1 in 2001.

 * ssh(1), sshd(8): update/replace the experimental post-quantum
   hybrid key exchange method based on Streamlined NTRU Prime coupled
   with X25519.

   The previous sntrup4591761x25519-sha512@tinyssh.org method is
   replaced with sntrup761x25519-sha512@openssh.com. Per its
   designers, the sntrup4591761 algorithm was superseded almost two
   years ago by sntrup761.

   (note this both the updated method and the one that it replaced are
   disabled by default)

 * ssh(1): disable CheckHostIP by default. It provides insignificant
   benefits while making key rotation significantly more difficult,
   especially for hosts behind IP-based load-balancers.

Changes since OpenSSH 8.4
=========================

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

 * ssh(1): this release enables UpdateHostkeys by default subject to
   some conservative preconditions:
    - The key was matched in the UserKnownHostsFile (and not in the
      GlobalKnownHostsFile).
    - The same key does not exist under another name.
    - A certificate host key is not in use.
    - known_hosts contains no matching wildcard hostname pattern.
    - VerifyHostKeyDNS is not enabled.
    - The default UserKnownHostsFile is in use.

   We expect some of these conditions will be modified or relaxed in
   future.

 * ssh(1), sshd(8): add a new LogVerbose configuration directive for
   that allows forcing maximum debug logging by file/function/line
   pattern-lists.

 * ssh(1): when prompting the user to accept a new hostkey, display
   any other host names/addresses already associated with the key.

 * ssh(1): allow UserKnownHostsFile=none to indicate that no
   known_hosts file should be used to identify host keys.

 * ssh(1): add a ssh_config KnownHostsCommand option that allows the
   client to obtain known_hosts data from a command in addition to
   the usual files.

 * ssh(1): add a ssh_config PermitRemoteOpen option that allows the
   client to restrict the destination when RemoteForward is used
   with SOCKS.

 * ssh(1): for FIDO keys, if a signature operation fails with a
   "incorrect PIN" reason and no PIN was initially requested from the
   user, then request a PIN and retry the operation. This supports
   some biometric devices that fall back to requiring PIN when reading
   of the biometric failed, and devices that require PINs for all
   hosted credentials.

 * sshd(8): implement client address-based rate-limiting via new
   sshd_config(5) PerSourceMaxStartups and PerSourceNetBlockSize
   directives that provide more fine-grained control on a per-origin
   address basis than the global MaxStartups limit.

Bugfixes
--------

 * ssh(1): Prefix keyboard interactive prompts with "(user@host)" to
   make it easier to determine which connection they are associated
   with in cases like scp -3, ProxyJump, etc. bz#3224

 * sshd(8): fix sshd_config SetEnv directives located inside Match
   blocks. GHPR201

 * ssh(1): when requesting a FIDO token touch on stderr, inform the
   user once the touch has been recorded.

 * ssh(1): prevent integer overflow when ridiculously large
   ConnectTimeout values are specified, capping the effective value
   (for most platforms) at 24 days. bz#3229

 * ssh(1): consider the ECDSA key subtype when ordering host key
   algorithms in the client.

 * ssh(1), sshd(8): rename the PubkeyAcceptedKeyTypes keyword to
   PubkeyAcceptedAlgorithms. The previous name incorrectly suggested
   that it control allowed key algorithms, when this option actually
   specifies the signature algorithms that are accepted. The previous
   name remains available as an alias. bz#3253

 * ssh(1), sshd(8): similarly, rename HostbasedKeyTypes (ssh) and
   HostbasedAcceptedKeyTypes (sshd) to HostbasedAcceptedAlgorithms.

 * sftp-server(8): add missing lsetstat@openssh.com documentation
   and advertisement in the server's SSH2_FXP_VERSION hello packet.

 * ssh(1), sshd(8): more strictly enforce KEX state-machine by
   banning packet types once they are received. Fixes memleak caused
   by duplicate SSH2_MSG_KEX_DH_GEX_REQUEST (oss-fuzz #30078).

 * sftp(1): allow the full range of UIDs/GIDs for chown/chgrp on 32bit
   platforms instead of being limited by LONG_MAX. bz#3206

 * Minor man page fixes (capitalization, commas, etc.) bz#3223

 * sftp(1): when doing an sftp recursive upload or download of a
   read-only directory, ensure that the directory is created with
   write and execute permissions in the interim so that the transfer
   can actually complete, then set the directory permission as the
   final step. bz#3222

 * ssh-keygen(1): document the -Z, check the validity of its argument
   earlier and provide a better error message if it's not correct.
   bz#2879

 * ssh(1): ignore comments at the end of config lines in ssh_config,
   similar to what we already do for sshd_config. bz#2320

 * sshd_config(5): mention that DisableForwarding is valid in a
   sshd_config Match block. bz3239

 * sftp(1): fix incorrect sorting of "ls -ltr" under some
   circumstances. bz3248.

 * ssh(1), sshd(8): fix potential integer truncation of (unlikely)
   timeout values. bz#3250

 * ssh(1): make hostbased authentication send the signature algorithm
   in its SSH2_MSG_USERAUTH_REQUEST packets instead of the key type.
   This make HostbasedAcceptedAlgorithms do what it is supposed to -
   filter on signature algorithm and not key type.

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

 * sshd(8): add a number of platform-specific syscalls to the Linux
   seccomp-bpf sandbox. bz#3232 bz#3260

 * sshd(8): remove debug message from sigchld handler that could cause
   deadlock on some platforms. bz#3259

 * Sync contrib/ssh-copy-id with upstream.

 * unittests: add a hostname function for systems that don't have it.
   Some systems don't have a hostname command (it's not required by
   POSIX). The do have uname -n (which is), but not all of those have
   it report the FQDN.

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

 - SHA1 (openssh-8.5.tar.gz) = 04cae43c389fb411227c01219e4eb46e3113f34e
 - SHA256 (openssh-8.5.tar.gz) = 5qB2CgzNG4io4DmChTjHgCWqRWvEOvCKJskLdJCz+SU=

 - SHA1 (openssh-8.5p1.tar.gz) = 72eadcbe313b07b1dd3b693e41d3cd56d354e24e
 - SHA256 (openssh-8.5p1.tar.gz) = 9S8/QdQpqpkY44zyAK8iXM3Y5m8FLaVyhwyJc3ZG7CU=

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 openssh@openssh.com

Revision 1.1.1.8 / (download) - annotate - [select for diffs] (vendor branch), Sat Apr 20 17:13:53 2019 UTC (4 years, 11 months ago) by christos
Branch: OPENSSH
CVS Tags: v84-20200927, v83-20200527, v82-20200214, v81-20191009, v80-20190417
Changes since 1.1.1.7: +4 -1 lines
Diff to previous 1.1.1.7 (colored)

Import 8.0:

Security
========

This release contains mitigation for a weakness in the scp(1) tool
and protocol (CVE-2019-6111): when copying files from a remote system
to a local directory, scp(1) did not verify that the filenames that
the server sent matched those requested by the client. This could
allow a hostile server to create or clobber unexpected local files
with attacker-controlled content.

This release adds client-side checking that the filenames sent from
the server match the command-line request,

The scp protocol is outdated, inflexible and not readily fixed. We
recommend the use of more modern protocols like sftp and rsync for
file transfer instead.

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

This release includes a number of changes that may affect existing
configurations:

 * scp(1): Relating to the above changes to scp(1); the scp protocol
   relies on the remote shell for wildcard expansion, so there is no
   infallible way for the client's wildcard matching to perfectly
   reflect the server's. If there is a difference between client and
   server wildcard expansion, the client may refuse files from the
   server. For this reason, we have provided a new "-T" flag to scp
   that disables these client-side checks at the risk of
   reintroducing the attack described above.

 * sshd(8): Remove support for obsolete "host/port" syntax. Slash-
   separated host/port was added in 2001 as an alternative to
   host:port syntax for the benefit of IPv6 users. These days there
   are establised standards for this like [::1]:22 and the slash
   syntax is easily mistaken for CIDR notation, which OpenSSH
   supports for some things. Remove the slash notation from
   ListenAddress and PermitOpen; bz#2335

Changes since OpenSSH 7.9
=========================

This release is focused on new features and internal refactoring.

New Features
------------

 * ssh(1), ssh-agent(1), ssh-add(1): Add support for ECDSA keys in
   PKCS#11 tokens.

 * ssh(1), sshd(8): Add experimental quantum-computing resistant
   key exchange method, based on a combination of Streamlined NTRU
   Prime 4591^761 and X25519.

 * ssh-keygen(1): Increase the default RSA key size to 3072 bits,
   following NIST Special Publication 800-57's guidance for a
   128-bit equivalent symmetric security level.

 * ssh(1): Allow "PKCS11Provider=none" to override later instances of
   the PKCS11Provider directive in ssh_config; bz#2974

 * sshd(8): Add a log message for situations where a connection is
   dropped for attempting to run a command but a sshd_config
   ForceCommand=internal-sftp restriction is in effect; bz#2960

 * ssh(1): When prompting whether to record a new host key, accept
   the key fingerprint as a synonym for "yes". This allows the user
   to paste a fingerprint obtained out of band at the prompt and
   have the client do the comparison for you.

 * ssh-keygen(1): When signing multiple certificates on a single
   command-line invocation, allow automatically incrementing the
   certificate serial number.

 * scp(1), sftp(1): Accept -J option as an alias to ProxyJump on
   the scp and sftp command-lines.

 * ssh-agent(1), ssh-pkcs11-helper(8), ssh-add(1): Accept "-v"
   command-line flags to increase the verbosity of output; pass
   verbose flags though to subprocesses, such as ssh-pkcs11-helper
   started from ssh-agent.

 * ssh-add(1): Add a "-T" option to allowing testing whether keys in
   an agent are usable by performing a signature and a verification.

 * sftp-server(8): Add a "lsetstat@openssh.com" protocol extension
   that replicates the functionality of the existing SSH2_FXP_SETSTAT
   operation but does not follow symlinks. bz#2067

 * sftp(1): Add "-h" flag to chown/chgrp/chmod commands to request
   they do not follow symlinks.

 * sshd(8): Expose $SSH_CONNECTION in the PAM environment. This makes
   the connection 4-tuple available to PAM modules that wish to use
   it in decision-making. bz#2741

 * sshd(8): Add a ssh_config "Match final" predicate Matches in same
   pass as "Match canonical" but doesn't require hostname
   canonicalisation be enabled. bz#2906

 * sftp(1): Support a prefix of '@' to suppress echo of sftp batch
   commands; bz#2926

 * ssh-keygen(1): When printing certificate contents using
   "ssh-keygen -Lf /path/certificate", include the algorithm that
   the CA used to sign the cert.

Bugfixes
--------

 * sshd(8): Fix authentication failures when sshd_config contains
   "AuthenticationMethods any" inside a Match block that overrides
   a more restrictive default.

 * sshd(8): Avoid sending duplicate keepalives when ClientAliveCount
   is enabled.

 * sshd(8): Fix two race conditions related to SIGHUP daemon restart.
   Remnant file descriptors in recently-forked child processes could
   block the parent sshd's attempt to listen(2) to the configured
   addresses. Also, the restarting parent sshd could exit before any
   child processes that were awaiting their re-execution state had
   completed reading it, leaving them in a fallback path.

 * ssh(1): Fix stdout potentially being redirected to /dev/null when
   ProxyCommand=- was in use.

 * sshd(8): Avoid sending SIGPIPE to child processes if they attempt
   to write to stderr after their parent processes have exited;
   bz#2071

 * ssh(1): Fix bad interaction between the ssh_config ConnectTimeout
   and ConnectionAttempts directives - connection attempts after the
   first were ignoring the requested timeout; bz#2918

 * ssh-keyscan(1): Return a non-zero exit status if no keys were
   found; bz#2903

 * scp(1): Sanitize scp filenames to allow UTF-8 characters without
   terminal control sequences;  bz#2434

 * sshd(8): Fix confusion between ClientAliveInterval and time-based
   RekeyLimit that could cause connections to be incorrectly closed.
   bz#2757

 * ssh(1), ssh-add(1): Correct some bugs in PKCS#11 token PIN
   handling at initial token login. The attempt to read the PIN
   could be skipped in some cases, particularly on devices with
   integrated PIN readers. This would lead to an inability to
   retrieve keys from these tokens. bz#2652

 * ssh(1), ssh-add(1): Support keys on PKCS#11 tokens that set the
   CKA_ALWAYS_AUTHENTICATE flag by requring a fresh login after the
   C_SignInit operation. bz#2638

 * ssh(1): Improve documentation for ProxyJump/-J, clarifying that
   local configuration does not apply to jump hosts.

 * ssh-keygen(1): Clarify manual - ssh-keygen -e only writes
   public keys, not private.

 * ssh(1), sshd(8): be more strict in processing protocol banners,
   allowing \r characters only immediately before \n.

 * Various: fix a number of memory leaks, including bz#2942 and
   bz#2938

 * scp(1), sftp(1): fix calculation of initial bandwidth limits.
   Account for bytes written before the timer starts and adjust the
   schedule on which recalculations are performed. Avoids an initial
   burst of traffic and yields more accurate bandwidth limits;
   bz#2927

 * sshd(8): Only consider the ext-info-c extension during the initial
   key eschange. It shouldn't be sent in subsequent ones, but if it
   is present we should ignore it. This prevents sshd from sending a
   SSH_MSG_EXT_INFO for REKEX for buggy these clients. bz#2929

 * ssh-keygen(1): Clarify manual that ssh-keygen -F (find host in
   authorized_keys) and -R (remove host from authorized_keys) options
   may accept either a bare hostname or a [hostname]:port combo.
   bz#2935

 * ssh(1): Don't attempt to connect to empty SSH_AUTH_SOCK; bz#2936

 * sshd(8): Silence error messages when sshd fails to load some of
   the default host keys. Failure to load an explicitly-configured
   hostkey is still an error, and failure to load any host key is
   still fatal. pr/103

 * ssh(1): Redirect stderr of ProxyCommands to /dev/null when ssh is
   started with ControlPersist; prevents random ProxyCommand output
   from interfering with session output.

 * ssh(1): The ssh client was keeping a redundant ssh-agent socket
   (leftover from authentication) around for the life of the
   connection; bz#2912

 * sshd(8): Fix bug in HostbasedAcceptedKeyTypes and
   PubkeyAcceptedKeyTypes options. If only RSA-SHA2 siganture types
   were specified, then authentication would always fail for RSA keys
   as the monitor checks only the base key (not the signature
   algorithm) type against *AcceptedKeyTypes. bz#2746

 * ssh(1): Request correct signature types from ssh-agent when
   certificate keys and RSA-SHA2 signatures are in use.

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

 * sshd(8): On Cygwin, run as SYSTEM where possible, using S4U for
   token creation if it supports MsV1_0 S4U Logon.

 * sshd(8): On Cygwin, use custom user/group matching code that
   respects the OS' behaviour of case-insensitive matching.

 * sshd(8): Don't set $MAIL if UsePAM=yes as PAM typically specifies
   the user environment if it's enabled; bz#2937

 * sshd(8) Cygwin: Change service name to cygsshd to avoid collision
   with Microsoft's OpenSSH port.

 * Allow building against OpenSSL -dev (3.x)

 * Fix a number of build problems against version configurations and
   versions of OpenSSL. Including bz#2931 and bz#2921

 * Improve warnings in cygwin service setup. bz#2922

 * Remove hardcoded service name in cygwin setup. bz#2922

Revision 1.1.1.7 / (download) - annotate - [select for diffs] (vendor branch), Fri Jul 3 00:54:45 2015 UTC (8 years, 9 months ago) by christos
Branch: OPENSSH
CVS Tags: v78-20180824, v77-20180405, v76-20171003, v75-20170418, v74-20161219, v73-20160802, v72-20160310, v71-20150821, v70-20150812, v69-20150630
Changes since 1.1.1.6: +3 -3 lines
Diff to previous 1.1.1.6 (colored)

Changes since OpenSSH 6.8
=========================

This is primarily a bugfix release.

Security
--------

 * ssh(1): when forwarding X11 connections with ForwardX11Trusted=no,
   connections made after ForwardX11Timeout expired could be permitted
   and no longer subject to XSECURITY restrictions because of an
   ineffective timeout check in ssh(1) coupled with "fail open"
   behaviour in the X11 server when clients attempted connections with
   expired credentials. This problem was reported by Jann Horn.

 * ssh-agent(1): fix weakness of agent locking (ssh-add -x) to
   password guessing by implementing an increasing failure delay,
   storing a salted hash of the password rather than the password
   itself and using a timing-safe comparison function for verifying
   unlock attempts. This problem was reported by Ryan Castellucci.

New Features
------------

 * ssh(1), sshd(8): promote chacha20-poly1305@openssh.com to be the
   default cipher

 * sshd(8): support admin-specified arguments to AuthorizedKeysCommand;
   bz#2081

 * sshd(8): add AuthorizedPrincipalsCommand that allows retrieving
   authorized principals information from a subprocess rather than
   a file.

 * ssh(1), ssh-add(1): support PKCS#11 devices with external PIN
   entry devices bz#2240

 * sshd(8): allow GSSAPI host credential check to be relaxed for
   multihomed hosts via GSSAPIStrictAcceptorCheck option; bz#928

 * ssh-keygen(1): support "ssh-keygen -lF hostname" to search
   known_hosts and print key hashes rather than full keys.

 * ssh-agent(1): add -D flag to leave ssh-agent in foreground without
   enabling debug mode; bz#2381

Bugfixes
--------

 * ssh(1), sshd(8): deprecate legacy SSH2_MSG_KEX_DH_GEX_REQUEST_OLD
   message and do not try to use it against some 3rd-party SSH
   implementations that use it (older PuTTY, WinSCP).

 * Many fixes for problems caused by compile-time deactivation of
   SSH1 support (including bz#2369)

 * ssh(1), sshd(8): cap DH-GEX group size at 4Kbits for Cisco
   implementations as some would fail when attempting to use group
   sizes >4K; bz#2209

 * ssh(1): fix out-of-bound read in EscapeChar configuration option
   parsing; bz#2396

 * sshd(8): fix application of PermitTunnel, LoginGraceTime,
   AuthenticationMethods and StreamLocalBindMask options in Match
   blocks

 * ssh(1), sshd(8): improve disconnection message on TCP reset;
   bz#2257

 * ssh(1): remove failed remote forwards established by muliplexing
   from the list of active forwards; bz#2363

 * sshd(8): make parsing of authorized_keys "environment=" options
   independent of PermitUserEnv being enabled; bz#2329

 * sshd(8): fix post-auth crash with permitopen=none; bz#2355

 * ssh(1), ssh-add(1), ssh-keygen(1): allow new-format private keys
   to be encrypted with AEAD ciphers; bz#2366

 * ssh(1): allow ListenAddress, Port and AddressFamily configuration
   options to appear in any order; bz#86

 * sshd(8): check for and reject missing arguments for VersionAddendum
   and ForceCommand; bz#2281

 * ssh(1), sshd(8): don't treat unknown certificate extensions as
   fatal; bz#2387

 * ssh-keygen(1): make stdout and stderr output consistent; bz#2325

 * ssh(1): mention missing DISPLAY environment in debug log when X11
   forwarding requested; bz#1682

 * sshd(8): correctly record login when UseLogin is set; bz#378

 * sshd(8): Add some missing options to sshd -T output and fix output
   of VersionAddendum and HostCertificate. bz#2346

 * Document and improve consistency of options that accept a "none"
   argument" TrustedUserCAKeys, RevokedKeys (bz#2382),
   AuthorizedPrincipalsFile (bz#2288)

 * ssh(1): include remote username in debug output; bz#2368

 * sshd(8): avoid compatibility problem with some versions of Tera
   Term, which would crash when they received the hostkeys notification
   message (hostkeys-00@openssh.com)

 * sshd(8): mention ssh-keygen -E as useful when comparing legacy MD5
   host key fingerprints; bz#2332

 * ssh(1): clarify pseudo-terminal request behaviour and use make
   manual language consistent; bz#1716

 * ssh(1): document that the TERM environment variable is not subject
   to SendEnv and AcceptEnv; bz#2386

Revision 1.1.1.6 / (download) - annotate - [select for diffs] (vendor branch), Fri Apr 3 23:49:25 2015 UTC (9 years ago) by christos
Branch: OPENSSH
CVS Tags: v68-20150318
Changes since 1.1.1.5: +23 -21 lines
Diff to previous 1.1.1.5 (colored)

Changes since OpenSSH 6.7
=========================

This is a major release, containing a number of new features as
well as a large internal re-factoring.

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

 * sshd(8): UseDNS now defaults to 'no'. Configurations that match
   against the client host name (via sshd_config or authorized_keys)
   may need to re-enable it or convert to matching against addresses.

New Features
------------

 * Much of OpenSSH's internal code has been re-factored to be more
   library-like. These changes are mostly not user-visible, but
   have greatly improved OpenSSH's testability and internal layout.

 * Add FingerprintHash option to ssh(1) and sshd(8), and equivalent
   command-line flags to the other tools to control algorithm used
   for key fingerprints. The default changes from MD5 to SHA256 and
   format from hex to base64.

   Fingerprints now have the hash algorithm prepended. An example of
   the new format: SHA256:mVPwvezndPv/ARoIadVY98vAC0g+P/5633yTC4d/wXE
   Please note that visual host keys will also be different.

 * ssh(1), sshd(8): Experimental host key rotation support. Add a
   protocol extension for a server to inform a client of all its
   available host keys after authentication has completed. The client
   may record the keys in known_hosts, allowing it to upgrade to better
   host key algorithms and a server to gracefully rotate its keys.

   The client side of this is controlled by a UpdateHostkeys config
   option (default off).

 * ssh(1): Add a ssh_config HostbasedKeyType option to control which
   host public key types are tried during host-based authentication.

 * ssh(1), sshd(8): fix connection-killing host key mismatch errors
   when sshd offers multiple ECDSA keys of different lengths.

 * ssh(1): when host name canonicalisation is enabled, try to
   parse host names as addresses before looking them up for
   canonicalisation. fixes bz#2074 and avoiding needless DNS
   lookups in some cases.

 * ssh-keygen(1), sshd(8): Key Revocation Lists (KRLs) no longer
   require OpenSSH to be compiled with OpenSSL support.

 * ssh(1), ssh-keysign(8): Make ed25519 keys work for host based
   authentication.

 * sshd(8): SSH protocol v.1 workaround for the Meyer, et al,
   Bleichenbacher Side Channel Attack. Fake up a bignum key before
   RSA decryption.

 * sshd(8): Remember which public keys have been used for
   authentication and refuse to accept previously-used keys.
   This allows AuthenticationMethods=publickey,publickey to require
   that users authenticate using two _different_ public keys.

 * sshd(8): add sshd_config HostbasedAcceptedKeyTypes and
   PubkeyAcceptedKeyTypes options to allow sshd to control what
   public key types will be accepted. Currently defaults to all.

 * sshd(8): Don't count partial authentication success as a failure
   against MaxAuthTries.

 * ssh(1): Add RevokedHostKeys option for the client to allow
   text-file or KRL-based revocation of host keys.

 * ssh-keygen(1), sshd(8): Permit KRLs that revoke certificates by
   serial number or key ID without scoping to a particular CA.

 * ssh(1): Add a "Match canonical" criteria that allows ssh_config
   Match blocks to trigger only in the second config pass.

 * ssh(1): Add a -G option to ssh that causes it to parse its
   configuration and dump the result to stdout, similar to "sshd -T".

 * ssh(1): Allow Match criteria to be negated. E.g. "Match !host".

 * The regression test suite has been extended to cover more OpenSSH
   features. The unit tests have been expanded and now cover key
   exchange.

Bugfixes

 * ssh-keyscan(1): ssh-keyscan has been made much more robust again
   servers that hang or violate the SSH protocol.

 * ssh(1), ssh-keygen(1): Fix regression bz#2306: Key path names were
   being lost as comment fields.

 * ssh(1): Allow ssh_config Port options set in the second config
   parse phase to be applied (they were being ignored). bz#2286

 * ssh(1): Tweak config re-parsing with host canonicalisation - make
   the second pass through the config files always run when host name
   canonicalisation is enabled (and not whenever the host name
   changes) bz#2267

 * ssh(1): Fix passing of wildcard forward bind addresses when
   connection multiplexing is in use; bz#2324;

 * ssh-keygen(1): Fix broken private key conversion from non-OpenSSH
   formats; bz#2345.

 * ssh-keygen(1): Fix KRL generation bug when multiple CAs are in
   use.

 * Various fixes to manual pages: bz#2288, bz#2316, bz#2273

Portable OpenSSH

 * Support --without-openssl at configure time

   Disables and removes dependency on OpenSSL. Many features,
   including SSH protocol 1 are not supported and the set of crypto
   options is greatly restricted. This will only work on systems
   with native arc4random or /dev/urandom.

   Considered highly experimental for now.

 * Support --without-ssh1 option at configure time

   Allows disabling support for SSH protocol 1.

 * sshd(8): Fix compilation on systems with IPv6 support in utmpx; bz#2296

 * Allow custom service name for sshd on Cygwin. Permits the use of
   multiple sshd running with different service names.

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

 - SHA1 (openssh-6.8.tar.gz) = 99903c6ca76e0a2c044711017f81127e12459d37
 - SHA256 (openssh-6.8.tar.gz) = N1uzVarFbrm2CzAwuDu3sRoszmqpK+5phAChP/QNyuw=

 - SHA1 (openssh-6.8p1.tar.gz) = cdbc51e46a902b30d263b05fdc71340920e91c92
 - SHA256 (openssh-6.8p1.tar.gz) = P/ZM5z7hJEgLW/dnuYMNfTwDu8tqvnFrePAZLDfOFg4=

Please note that the PGP key used to sign releases was recently rotated.
The new key has been signed by the old key to provide continuity. It is
available from the mirror sites as RELEASE_KEY.asc.

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

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

OpenSSH is brought to you by Markus Friedl, Niels Provos, Theo de Raadt,
Kevin Steves, Damien Miller, Darren Tucker, Jason McIntyre, Tim Rice and
Ben Lindstrom.

Revision 1.1.1.5 / (download) - annotate - [select for diffs] (vendor branch), Sun Oct 19 16:28:37 2014 UTC (9 years, 5 months ago) by christos
Branch: OPENSSH
CVS Tags: v67-20141018
Changes since 1.1.1.4: +9 -7 lines
Diff to previous 1.1.1.4 (colored)

Changes since OpenSSH 6.6
=========================

Potentially-incompatible changes

 * sshd(8): The default set of ciphers and MACs has been altered to
   remove unsafe algorithms. In particular, CBC ciphers and arcfour*
   are disabled by default.

   The full set of algorithms remains available if configured
   explicitly via the Ciphers and MACs sshd_config options.

 * sshd(8): Support for tcpwrappers/libwrap has been removed.

 * OpenSSH 6.5 and 6.6 have a bug that causes ~0.2% of connections
   using the curve25519-sha256@libssh.org KEX exchange method to fail
   when connecting with something that implements the specification
   correctly. OpenSSH 6.7 disables this KEX method when speaking to
   one of the affected versions.

New Features

 * Major internal refactoring to begin to make part of OpenSSH usable
   as a library. So far the wire parsing, key handling and KRL code
   has been refactored. Please note that we do not consider the API
   stable yet, nor do we offer the library in separable form.

 * ssh(1), sshd(8): Add support for Unix domain socket forwarding.
   A remote TCP port may be forwarded to a local Unix domain socket
   and vice versa or both ends may be a Unix domain socket.

 * ssh(1), ssh-keygen(1): Add support for SSHFP DNS records for
   ED25519 key types.

 * sftp(1): Allow resumption of interrupted uploads.

 * ssh(1): When rekeying, skip file/DNS lookups of the hostkey if it
   is the same as the one sent during initial key exchange; bz#2154

 * sshd(8): Allow explicit ::1 and 127.0.0.1 forwarding bind
   addresses when GatewayPorts=no; allows client to choose address
   family; bz#2222

 * sshd(8): Add a sshd_config PermitUserRC option to control whether
   ~/.ssh/rc is executed, mirroring the no-user-rc authorized_keys
   option; bz#2160

 * ssh(1): Add a %C escape sequence for LocalCommand and ControlPath
   that expands to a unique identifer based on a hash of the tuple of
   (local host, remote user, hostname, port). Helps avoid exceeding
   miserly pathname limits for Unix domain sockets in multiplexing
   control paths; bz#2220

 * sshd(8): Make the "Too many authentication failures" message
   include the user, source address, port and protocol in a format
   similar to the authentication success / failure messages; bz#2199

 * Added unit and fuzz tests for refactored code. These are run
   automatically in portable OpenSSH via the "make tests" target.

Bugfixes

 * sshd(8): Fix remote forwarding with the same listen port but
   different listen address.

 * ssh(1): Fix inverted test that caused PKCS#11 keys that were
   explicitly listed in ssh_config or on the commandline not to be
   preferred.

 * ssh-keygen(1): Fix bug in KRL generation: multiple consecutive
   revoked certificate serial number ranges could be serialised to an
   invalid format. Readers of a broken KRL caused by this bug will
   fail closed, so no should-have-been-revoked key will be accepted.

 * ssh(1): Reflect stdio-forward ("ssh -W host:port ...") failures in
   exit status. Previously we were always returning 0; bz#2255

 * ssh(1), ssh-keygen(1): Make Ed25519 keys' title fit properly in the
   randomart border; bz#2247

 * ssh-agent(1): Only cleanup agent socket in the main agent process
   and not in any subprocesses it may have started (e.g. forked
   askpass). Fixes agent sockets being zapped when askpass processes
   fatal(); bz#2236

 * ssh-add(1): Make stdout line-buffered; saves partial output getting
   lost when ssh-add fatal()s part-way through (e.g. when listing keys
   from an agent that supports key types that ssh-add doesn't);
   bz#2234

 * ssh-keygen(1): When hashing or removing hosts, don't choke on
   @revoked markers and don't remove @cert-authority markers; bz#2241

 * ssh(1): Don't fatal when hostname canonicalisation fails and a
   ProxyCommand is in use; continue and allow the ProxyCommand to
   connect anyway (e.g. to a host with a name outside the DNS behind
   a bastion)

 * scp(1): When copying local->remote fails during read, don't send
   uninitialised heap to the remote end.

 * sftp(1): Fix fatal "el_insertstr failed" errors when tab-completing
   filenames with  a single quote char somewhere in the string;
   bz#2238

 * ssh-keyscan(1): Scan for Ed25519 keys by default.

 * ssh(1): When using VerifyHostKeyDNS with a DNSSEC resolver, down-
   convert any certificate keys to plain keys and attempt SSHFP
   resolution.  Prevents a server from skipping SSHFP lookup and
   forcing a new-hostkey dialog by offering only certificate keys.

 * sshd(8): Avoid crash at exit via NULL pointer reference; bz#2225

 * Fix some strict-alignment errors.

Portable OpenSSH

 * Portable OpenSSH now supports building against libressl-portable.

 * Portable OpenSSH now requires openssl 0.9.8f or greater. Older
   versions are no longer supported.

 * In the OpenSSL version check, allow fix version upgrades (but not
   downgrades. Debian bug #748150.

 * sshd(8): On Cygwin, determine privilege separation user at runtime,
   since it may need to be a domain account.

 * sshd(8): Don't attempt to use vhangup on Linux. It doesn't work for
   non-root users, and for them it just messes up the tty settings.

 * Use CLOCK_BOOTTIME in preference to CLOCK_MONOTONIC when it is
   available. It considers time spent suspended, thereby ensuring
   timeouts (e.g. for expiring agent keys) fire correctly.  bz#2228

 * Add support for ed25519 to opensshd.init init script.

 * sftp-server(8): On platforms that support it, use prctl() to
   prevent sftp-server from accessing /proc/self/{mem,maps}

Changes since OpenSSH 6.5
=========================

This is primarily a bugfix release.

Security:

 * sshd(8): when using environment passing with a sshd_config(5)
   AcceptEnv pattern with a wildcard. OpenSSH prior to 6.6 could be
   tricked into accepting any enviornment variable that contains the
   characters before the wildcard character.

New / changed features:

 * ssh(1), sshd(8): this release removes the J-PAKE authentication code.
   This code was experimental, never enabled and had been unmaintained
   for some time.

 * ssh(1): when processing Match blocks, skip 'exec' clauses other clauses
   predicates failed to match.

 * ssh(1): if hostname canonicalisation is enabled and results in the
   destination hostname being changed, then re-parse ssh_config(5) files
   using the new destination hostname. This gives 'Host' and 'Match'
   directives that use the expanded hostname a chance to be applied.

Bugfixes:

 * ssh(1): avoid spurious "getsockname failed: Bad file descriptor" in
   ssh -W. bz#2200, debian#738692

 * sshd(8): allow the shutdown(2) syscall in seccomp-bpf and systrace
   sandbox modes, as it is reachable if the connection is terminated
   during the pre-auth phase.

 * ssh(1), sshd(8): fix unsigned overflow that in SSH protocol 1 bignum
   parsing. Minimum key length checks render this bug unexploitable to
   compromise SSH 1 sessions.

 * sshd_config(5): clarify behaviour of a keyword that appears in
   multiple matching Match blocks. bz#2184

 * ssh(1): avoid unnecessary hostname lookups when canonicalisation is
   disabled. bz#2205

 * sshd(8): avoid sandbox violation crashes in GSSAPI code by caching
   the supported list of GSSAPI mechanism OIDs before entering the
   sandbox. bz#2107

 * ssh(1): fix possible crashes in SOCKS4 parsing caused by assumption
   that the SOCKS username is nul-terminated.

 * ssh(1): fix regression for UsePrivilegedPort=yes when BindAddress is
   not specified.

 * ssh(1), sshd(8): fix memory leak in ECDSA signature verification.

 * ssh(1): fix matching of 'Host' directives in ssh_config(5) files
   to be case-insensitive again (regression in 6.5).

Portable OpenSSH:

 * sshd(8): don't fatal if the FreeBSD Capsicum is offered by the
   system headers and libc but is not supported by the kernel.
 * Fix build using the HP-UX compiler.

Changes since OpenSSH 6.4
=========================

This is a feature-focused release.

New features:

 * ssh(1), sshd(8): Add support for key exchange using elliptic-curve
   Diffie Hellman in Daniel Bernstein's Curve25519. This key exchange
   method is the default when both the client and server support it.

 * ssh(1), sshd(8): Add support for Ed25519 as a public key type.
   Ed25519 is a elliptic curve signature scheme that offers
   better security than ECDSA and DSA and good performance. It may be
   used for both user and host keys.

 * Add a new private key format that uses a bcrypt KDF to better
   protect keys at rest. This format is used unconditionally for
   Ed25519 keys, but may be requested when generating or saving
   existing keys of other types via the -o ssh-keygen(1) option.
   We intend to make the new format the default in the near future.
   Details of the new format are in the PROTOCOL.key file.

 * ssh(1), sshd(8): Add a new transport cipher
   "chacha20-poly1305@openssh.com" that combines Daniel Bernstein's
   ChaCha20 stream cipher and Poly1305 MAC to build an authenticated
   encryption mode. Details are in the PROTOCOL.chacha20poly1305 file.

 * ssh(1), sshd(8): Refuse RSA keys from old proprietary clients and
   servers that use the obsolete RSA+MD5 signature scheme. It will
   still be possible to connect with these clients/servers but only
   DSA keys will be accepted, and OpenSSH will refuse connection
   entirely in a future release.

 * ssh(1), sshd(8): Refuse old proprietary clients and servers that
   use a weaker key exchange hash calculation.

 * ssh(1): Increase the size of the Diffie-Hellman groups requested
   for each symmetric key size. New values from NIST Special
   Publication 800-57 with the upper limit specified by RFC4419.

 * ssh(1), ssh-agent(1): Support PKCS#11 tokens that only provide
   X.509 certs instead of raw public keys (requested as bz#1908).

 * ssh(1): Add a ssh_config(5) "Match" keyword that allows
   conditional configuration to be applied by matching on hostname,
   user and result of arbitrary commands.

 * ssh(1): Add support for client-side hostname canonicalisation
   using a set of DNS suffixes and rules in ssh_config(5). This
   allows unqualified names to be canonicalised to fully-qualified
   domain names to eliminate ambiguity when looking up keys in
   known_hosts or checking host certificate names.

 * sftp-server(8): Add the ability to whitelist and/or blacklist sftp
   protocol requests by name.

 * sftp-server(8): Add a sftp "fsync@openssh.com" to support calling
   fsync(2) on an open file handle.

 * sshd(8): Add a ssh_config(5) PermitTTY to disallow TTY allocation,
   mirroring the longstanding no-pty authorized_keys option.

 * ssh(1): Add a ssh_config ProxyUseFDPass option that supports the
   use of ProxyCommands that establish a connection and then pass a
   connected file descriptor back to ssh(1). This allows the
   ProxyCommand to exit rather than staying around to transfer data.

Bugfixes:

 * ssh(1), sshd(8): Fix potential stack exhaustion caused by nested
   certificates.

 * ssh(1): bz#1211: make BindAddress work with UsePrivilegedPort.

 * sftp(1): bz#2137: fix the progress meter for resumed transfer.

 * ssh-add(1): bz#2187: do not request smartcard PIN when removing
   keys from ssh-agent.

 * sshd(8): bz#2139: fix re-exec fallback when original sshd binary
   cannot be executed.

 * ssh-keygen(1): Make relative-specified certificate expiry times
   relative to current time and not the validity start time.

 * sshd(8): bz#2161: fix AuthorizedKeysCommand inside a Match block.

 * sftp(1): bz#2129: symlinking a file would incorrectly canonicalise
   the target path.

 * ssh-agent(1): bz#2175: fix a use-after-free in the PKCS#11 agent
   helper executable.

 * sshd(8): Improve logging of sessions to include the user name,
   remote host and port, the session type (shell, command, etc.) and
   allocated TTY (if any).

 * sshd(8): bz#1297: tell the client (via a debug message) when
   their preferred listen address has been overridden by the
   server's GatewayPorts setting.

 * sshd(8): bz#2162: include report port in bad protocol banner
   message.

 * sftp(1): bz#2163: fix memory leak in error path in do_readdir().

 * sftp(1): bz#2171: don't leak file descriptor on error.

 * sshd(8): Include the local address and port in "Connection from
   ..." message (only shown at loglevel>=verbose).

Portable OpenSSH:

 * Please note that this is the last version of Portable OpenSSH that
   will support versions of OpenSSL prior to 0.9.6. Support (i.e.
   SSH_OLD_EVP) will be removed following the 6.5p1 release.

 * Portable OpenSSH will attempt compile and link as a Position
   Independent Executable on Linux, OS X and OpenBSD on recent gcc-
   like compilers. Other platforms and older/other compilers may
   request this using the --with-pie configure flag.

 * A number of other toolchain-related hardening options are used
   automatically if available, including -ftrapv to abort on signed
   integer overflow and options to write-protect dynamic linking
   information.  The use of these options may be disabled using the
   --without-hardening configure flag.

 * If the toolchain supports it, one of the -fstack-protector-strong,
   -fstack-protector-all or -fstack-protector compilation flag are
   used to add guards to mitigate attacks based on stack overflows.
   The use of these options may be disabled using the
   --without-stackprotect configure option.

 * sshd(8): Add support for pre-authentication sandboxing using the
   Capsicum API introduced in FreeBSD 10.

 * Switch to a ChaCha20-based arc4random() PRNG for platforms that do
   not provide their own.

 * sshd(8): bz#2156: restore Linux oom_adj setting when handling
   SIGHUP to maintain behaviour over retart.

 * sshd(8): bz#2032: use local username in krb5_kuserok check rather
   than full client name which may be of form user@REALM.

 * ssh(1), sshd(8): Test for both the presence of ECC NID numbers in
   OpenSSL and that they actually work. Fedora (at least) has
   NID_secp521r1 that doesn't work.

 * bz#2173: use pkg-config --libs to include correct -L location for
   libedit.

Revision 1.1.1.4 / (download) - annotate - [select for diffs] (vendor branch), Fri Nov 8 17:58:11 2013 UTC (10 years, 5 months ago) by christos
Branch: OPENSSH
CVS Tags: v64-20131107
Changes since 1.1.1.3: +3 -3 lines
Diff to previous 1.1.1.3 (colored)

Import new openssh to address

Changes since OpenSSH 6.3
=========================

This release fixes a security bug:

 * sshd(8): fix a memory corruption problem triggered during rekeying
   when an AES-GCM cipher is selected. Full details of the vulnerability
   are available at: http://www.openssh.com/txt/gcmrekey.adv

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

 - SHA1 (openssh-6.4.tar.gz) = 4caf1a50eb3a3da821c16298c4aaa576fe24210c
 - SHA1 (openssh-6.4p1.tar.gz) = cf5fe0eb118d7e4f9296fbc5d6884965885fc55d

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

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

OpenSSH is brought to you by Markus Friedl, Niels Provos, Theo de Raadt,
Kevin Steves, Damien Miller, Darren Tucker, Jason McIntyre, Tim Rice and
Ben Lindstrom.

Revision 1.1.1.3 / (download) - annotate - [select for diffs] (vendor branch), Sun Jul 24 15:08:42 2011 UTC (12 years, 8 months ago) by christos
Branch: OPENSSH
CVS Tags: v62-20130321, v61-20120828, v60-20120421, v59-20110906, v58-20110724
Changes since 1.1.1.2: +5 -3 lines
Diff to previous 1.1.1.2 (colored)

from ftp.openbsd.org

Revision 1.1.1.2 / (download) - annotate - [select for diffs] (vendor branch), Sun Nov 21 17:05:57 2010 UTC (13 years, 4 months ago) by adam
Branch: OPENSSH
CVS Tags: v56-20101121
Changes since 1.1.1.1: +18 -3 lines
Diff to previous 1.1.1.1 (colored)

Imported openssh-5.6

Revision 1.1.1.1 / (download) - annotate - [select for diffs] (vendor branch), Sun Jun 7 22:19:20 2009 UTC (14 years, 10 months ago) by christos
Branch: OPENSSH
CVS Tags: v53-20091226, v52-20090607
Changes since 1.1: +0 -0 lines
Diff to previous 1.1 (colored)

import 5.2 from ftp.openbsd.org

This form allows you to request diff's between any two revisions of a file. You may select a symbolic revision name using the selection box or you may type in a numeric name using the type-in text box.




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