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Bug#873201: marked as done (openssh-client: command line parsing with -- between option and non-option arguments completely broken)

Your message dated Fri, 06 Oct 2017 12:06:10 +0000
with message-id <E1e0ROM-0000c3-AV@fasolo.debian.org>
and subject line Bug#873201: fixed in openssh 1:7.6p1-1
has caused the Debian Bug report #873201,
regarding openssh-client: command line parsing with -- between option and non-option arguments completely broken
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner@bugs.debian.org
immediately.)


-- 
873201: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=873201
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: openssh-client
Version: 1:7.5p1-7
Severity: grave
Tags: upstream security
Justification: user security hole

Dear Debian maintainer,

I was intending to report this upstream, but, contrary to the documentation
     * [9]openssh-unix-dev@mindrot.org This is a public list and is open to posting from non-subscribed
       users.
on https://www.openssh.com/report.html the upstream mailing list is not
open for postings, as I got a rejection message…
> Posting by non-members to openssh-unix-dev@mindrot.org is currently
> disabled, sorry.
… so please forward this upstream, as is a package maintainer’s duty.

Original message follows:

-----cutting here may damage your screen surface-----
From: Thorsten Glaser <t.glaser@tarent.de>
Message-ID: <alpine.DEB.2.20.1708251545580.2732@tglase.lan.tarent.de>
To: openssh-unix-dev@mindrot.org
Date: Fri, 25 Aug 2017 15:57:47 +0200 (CEST)
Subject: command line parsing with -- between option and non-option arguments completely broken

Hi,

in the process of me fixing CVE-2017-12836 a user noticed a
problem with OpenSSH’s command line parsing.

I’ve verified these on OpenSSH 5.3 (MirBSD) and 7.5p1 (Debian).

So, to begin with, this command _should_ spawn xeyes:

$ ssh -oProxyCommand=xeyes vuxu.org

This command _could_ spawn xeyes on glibc systems, but
probably shouldn’t on POSIX or BSD systems:

$ ssh vuxu.org -oProxyCommand=xeyes

This command properly does not spawn xeyes but tries to
resolve “-oProxyCommand=xeyes” as hostname, correctly failing:

$ ssh -- -oProxyCommand=xeyes

This command *must not* spawn xeyes, but does:

$ ssh -- vuxu.org -oProxyCommand=xeyes

This instead must execute “-oProxyCommand=xeyes” as command
on the remote side.

Interestingly enough, this command works the same and also
mustn’t but also doesn’t:

$ ssh vuxu.org -- -oProxyCommand=xeyes

Now it gets completely weird, this doesn’t spawn xeyes either:

$ ssh -- vuxu.org -- -oProxyCommand=xeyes

This “should” execute “--” as command with “-oProxyCommand=xeyes”
as its first option on the remote site, but judging from the error
| mksh: ProxyCommand=xeyes: unknown option
it instead passes “-oProxyCommand=xeyes” as option to a shell on
the remote side.

I don’t do the security theatre, but this could perhaps be considered
missing command escaping on the remote side (passing what would be a
command as an option to the remote shell) in addition to completely
fucked up option parsing on the local side.

This was first reported by nickserv-auth’d user jn__ on #musl on
Freenode IRC, and leah2 forwarded it to me as current de-facto
maintainer of GNU CVS because I considered adding “--” between
option and nōn-option arguments sufficient for fixing the afore‐
mentioned CVE, judging this effective enough with normal command
line parsing rules (as in getopt(3) on OpenBSD) and given the
.Sx SYNOPSIS
in the ssh manpage.

bye,
//mirabilos

PS: Please keep me in Cc, I’m not subscribed to the list.
-----cutting here may damage your screen surface-----

Thanks!

PS: This affects cvs in wheezy, jessie and stretch but not sid.


-- System Information:
Debian Release: buster/sid
  APT prefers unreleased
  APT policy: (500, 'unreleased'), (500, 'buildd-unstable'), (500, 'unstable')
Architecture: x32 (x86_64)
Foreign Architectures: i386, amd64

Kernel: Linux 4.11.0-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=C, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=C (charmap=UTF-8)
Shell: /bin/sh linked to /bin/lksh
Init: sysvinit (via /sbin/init)

Versions of packages openssh-client depends on:
ii  adduser           3.116
ii  dpkg              1.18.24
ii  libc6             2.24-14
ii  libedit2          3.1-20170329-1
ii  libgssapi-krb5-2  1.15.1-2
ii  libselinux1       2.6-3+b2
ii  libssl1.0.2       1.0.2l-2
ii  passwd            1:4.4-4.1
ii  zlib1g            1:1.2.8.dfsg-5

Versions of packages openssh-client recommends:
ii  xauth  1:1.0.9-1

Versions of packages openssh-client suggests:
pn  keychain                  <none>
ii  kwalletcli [ssh-askpass]  3.00-1
pn  libpam-ssh                <none>
pn  monkeysphere              <none>

-- Configuration Files:
/etc/ssh/moduli changed [not included]
/etc/ssh/ssh_config changed [not included]

-- no debconf information

--- End Message ---
--- Begin Message --- 
Source: openssh
Source-Version: 1:7.6p1-1

We believe that the bug you reported is fixed in the latest version of
openssh, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 873201@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Colin Watson <cjwatson@debian.org> (supplier of updated openssh package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Format: 1.8
Date: Fri, 06 Oct 2017 12:36:48 +0100
Source: openssh
Binary: openssh-client openssh-server openssh-sftp-server ssh ssh-krb5 ssh-askpass-gnome openssh-client-udeb openssh-server-udeb
Architecture: source
Version: 1:7.6p1-1
Distribution: unstable
Urgency: medium
Maintainer: Debian OpenSSH Maintainers <debian-ssh@lists.debian.org>
Changed-By: Colin Watson <cjwatson@debian.org>
Description:
 openssh-client - secure shell (SSH) client, for secure access to remote machines
 openssh-client-udeb - secure shell client for the Debian installer (udeb)
 openssh-server - secure shell (SSH) server, for secure access from remote machines
 openssh-server-udeb - secure shell server for the Debian installer (udeb)
 openssh-sftp-server - secure shell (SSH) sftp server module, for SFTP access from remot
 ssh        - secure shell client and server (metapackage)
 ssh-askpass-gnome - interactive X program to prompt users for a passphrase for ssh-ad
 ssh-krb5   - secure shell client and server (transitional package)
Closes: 873201 877800
Changes:
 openssh (1:7.6p1-1) unstable; urgency=medium
 .
   * New upstream release (https://www.openssh.com/txt/release-7.6):
     - SECURITY: sftp-server(8): In read-only mode, sftp-server was
       incorrectly permitting creation of zero-length files. Reported by
       Michal Zalewski.
     - ssh(1): Delete SSH protocol version 1 support, associated
       configuration options and documentation (LP: #1584321).
     - ssh(1)/sshd(8): Remove support for the hmac-ripemd160 MAC.
     - ssh(1)/sshd(8): Remove support for the arcfour, blowfish and CAST
       ciphers.
     - Refuse RSA keys <1024 bits in length and improve reporting for keys
       that do not meet this requirement.
     - ssh(1): Do not offer CBC ciphers by default.
     - ssh(1): Add RemoteCommand option to specify a command in the ssh
       config file instead of giving it on the client's command line.  This
       allows the configuration file to specify the command that will be
       executed on the remote host.
     - sshd(8): Add ExposeAuthInfo option that enables writing details of the
       authentication methods used (including public keys where applicable)
       to a file that is exposed via a $SSH_USER_AUTH environment variable in
       the subsequent session.
     - ssh(1): Add support for reverse dynamic forwarding.  In this mode, ssh
       will act as a SOCKS4/5 proxy and forward connections to destinations
       requested by the remote SOCKS client.  This mode is requested using
       extended syntax for the -R and RemoteForward options and, because it
       is implemented solely at the client, does not require the server be
       updated to be supported.
     - sshd(8): Allow LogLevel directive in sshd_config Match blocks.
     - ssh-keygen(1): Allow inclusion of arbitrary string or flag certificate
       extensions and critical options.
     - ssh-keygen(1): Allow ssh-keygen to use a key held in ssh-agent as a CA
       when signing certificates.
     - ssh(1)/sshd(8): Allow IPQoS=none in ssh/sshd to not set an explicit
       ToS/DSCP value and just use the operating system default.
     - ssh-add(1): Add -q option to make ssh-add quiet on success.
     - ssh(1): Expand the StrictHostKeyChecking option with two new settings.
       The first "accept-new" will automatically accept hitherto-unseen keys
       but will refuse connections for changed or invalid hostkeys.  This is
       a safer subset of the current behaviour of StrictHostKeyChecking=no.
       The second setting "off", is a synonym for the current behaviour of
       StrictHostKeyChecking=no: accept new host keys, and continue
       connection for hosts with incorrect hostkeys.  A future release will
       change the meaning of StrictHostKeyChecking=no to the behaviour of
       "accept-new".
     - ssh(1): Add SyslogFacility option to ssh(1) matching the equivalent
       option in sshd(8).
     - ssh(1): Use HostKeyAlias if specified instead of hostname for matching
       host certificate principal names.
     - sftp(1): Implement sorting for globbed ls.
     - ssh(1): Add a user@host prefix to client's "Permission denied"
       messages, useful in particular when using "stacked" connections (e.g.
       ssh -J) where it's not clear which host is denying.
     - ssh(1): Accept unknown EXT_INFO extension values that contain \0
       characters.  These are legal, but would previously cause fatal
       connection errors if received.
     - sftp(1): Print '?' instead of incorrect link count (that the protocol
       doesn't provide) for remote listings.
     - ssh(1): Return failure rather than fatal() for more cases during
       session multiplexing negotiations.  Causes the session to fall back to
       a non-mux connection if they occur.
     - ssh(1): Mention that the server may send debug messages to explain
       public key authentication problems under some circumstances.
     - Translate OpenSSL error codes to better report incorrect passphrase
       errors when loading private keys.
     - sshd(8): Adjust compatibility patterns for WinSCP to correctly
       identify versions that implement only the legacy DH group exchange
       scheme (closes: #877800).
     - ssh(1): Print the "Killed by signal 1" message only at LogLevel
       verbose so that it is not shown at the default level; prevents it from
       appearing during ssh -J and equivalent ProxyCommand configs.
     - ssh-keygen(1): When generating all hostkeys (ssh-keygen -A), clobber
       existing keys if they exist but are zero length.  Zero-length keys
       could previously be made if ssh-keygen failed or was interrupted part
       way through generating them.
     - ssh-keyscan(1): Avoid double-close() on file descriptors.
     - sshd(8): Avoid reliance on shared use of pointers shared between
       monitor and child sshd processes.
     - sshd_config(8): Document available AuthenticationMethods.
     - ssh(1): Avoid truncation in some login prompts.
     - ssh(1): Make "--" before the hostname terminate argument processing
       after the hostname too (closes: #873201).
     - ssh-keygen(1): Switch from aes256-cbc to aes256-ctr for encrypting
       new-style private keys.
     - ssh(1): Warn and do not attempt to use keys when the public and
       private halves do not match.
     - sftp(1): Don't print verbose error message when ssh disconnects from
       under sftp.
     - sshd(8): Fix keepalive scheduling problem: prevent activity on a
       forwarded port from preventing the keepalive from being sent.
     - sshd(8): When started without root privileges, don't require the
       privilege separation user or path to exist.
     - ssh(1)/sshd(8): Correctness fix for channels implementation: accept
       channel IDs greater than 0x7FFFFFFF.
     - sshd(8): Expose list of completed authentication methods to PAM via
       the SSH_AUTH_INFO_0 PAM environment variable.
     - ssh(1)/sshd(8): Fix several problems in the tun/tap forwarding code,
       mostly to do with host/network byte order confusion.
     - sshd(8): Avoid Linux seccomp violations on ppc64le over the socketcall
       syscall.
   * Build-depend on debhelper (>= 9.20160709~) rather than dh-systemd.
   * Change priorities of ssh and ssh-krb5 binary packages to optional, since
     "Priority: extra" is now deprecated.
   * Use HTTPS form of copyright-format URL.
   * Adjust "Running sshd from inittab" instructions in README.Debian to
     recommend using service(8) rather than calling the init script directly.
   * Policy version 4.1.0.
   * Adjust "Per-connection sshd instances with systemd" instructions in
     README.Debian to recommend using a drop-in file rather than copying and
     modifying the ssh.socket unit file.
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