Re: [PATCH] openssh: Update to 8.6p1

[Michael Tremer <michael.tremer@ipfire.org>]

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Good morning,

Special thanks for this :)

-Michael

> On 19 Apr 2021, at 21:58, Adolf Belka <adolf.belka(a)ipfire.org> wrote:
> 
> - Update from 8.5p1 to 8.6p1
> - Update of rootfile not needed
> - Changelog
> 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(a)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(a)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(a)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. GHPR174
> * ssh(1): ensure that pkcs11_del_provider() is called before exit.
>   GHPR234
> * 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. GHPR223
> * 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
> 
> Signed-off-by: Adolf Belka <adolf.belka(a)ipfire.org>
> ---
> lfs/openssh | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lfs/openssh b/lfs/openssh
> index 2a07d9e65..3117e996c 100644
> --- a/lfs/openssh
> +++ b/lfs/openssh
> @@ -24,7 +24,7 @@
> 
> include Config
> 
> -VER        = 8.5p1
> +VER        = 8.6p1
> 
> THISAPP    = openssh-$(VER)
> DL_FILE    = $(THISAPP).tar.gz
> @@ -40,7 +40,7 @@ objects = $(DL_FILE)
> 
> $(DL_FILE) = $(DL_FROM)/$(DL_FILE)
> 
> -$(DL_FILE)_MD5 = 9eb9420cf587edc26f8998ab679ad390
> +$(DL_FILE)_MD5 = 805f7048aec6dd752584e570383a6f00
> 
> install : $(TARGET)
> 
> -- 
> 2.31.1
>