Bug#513235: gnome-keyring: selects wrong key when multiple ssh identities are used

Tue Jan 27 14:43:55 UTC 2009

Package: gnome-keyring
Version: 2.22.3-2
Severity: critical
Tags: security
Justification: breaks unrelated software

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/usr/bin/gnome-keyring-daemon breaks ssh as detailed below, justifying critical
severity.  The breakage may lead to information leakage due to the unexpected
behaviour it causes for ssh.

I regularily log into a system which uses different ssh keys to select different 
configurations.  This fails if gnome-keyring-daemon is running.  It seems to use
previously learned keys even if you specify "ssh -i <keyfile>", or use the
IdentityFile keyword in ~/.ssh/config.

Example ssh session with gnome-keyring-daemon (after already authenticating 
with the remote server using another key):

bjorn at nemi:~$ ssh -v rocs2
OpenSSH_5.1p1 Debian-5, OpenSSL 0.9.8g 19 Oct 2007
debug1: Reading configuration data /home/bjorn/.ssh/config
debug1: Applying options for rocs2
debug1: Applying options for *
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to login.example.com [10.1.1.82] port 22.
debug1: Connection established.
debug1: identity file /home/bjorn/.ssh/key2 type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.5
debug1: match: OpenSSH_4.5 pat OpenSSH_4*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-5
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 zlib at openssh.com
debug1: kex: client->server aes128-cbc hmac-md5 zlib at openssh.com
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'login.example.com' is known and matches the DSA host key.
debug1: Found key in /home/bjorn/.ssh/known_hosts:15
debug1: ssh_dss_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Offering public key: 
debug1: Server accepts key: pkalg ssh-dss blen 434
debug1: Enabling compression at level 6.
debug1: Authentication succeeded (publickey).

Notice the difference after stopping gnome-keyring-daemon:

bjorn at nemi:~$ ssh -v rocs2
OpenSSH_5.1p1 Debian-5, OpenSSL 0.9.8g 19 Oct 2007
debug1: Reading configuration data /home/bjorn/.ssh/config
debug1: Applying options for rocs2
debug1: Applying options for *
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to login.example.com [10.1.1.82] port 22.
debug1: Connection established.
debug1: identity file /home/bjorn/.ssh/key2 type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.5
debug1: match: OpenSSH_4.5 pat OpenSSH_4*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-5
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 zlib at openssh.com
debug1: kex: client->server aes128-cbc hmac-md5 zlib at openssh.com
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'login.example.com' is known and matches the DSA host key.
debug1: Found key in /home/bjorn/.ssh/known_hosts:115
debug1: ssh_dss_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Trying private key: /home/bjorn/.ssh/key2
debug1: read PEM private key done: type DSA
debug1: Remote: Adding to environment: SSH_TARGET=key2
debug1: Enabling compression at level 6.
debug1: Authentication succeeded (publickey).

Notice how the second example actually uses the key "key2", which causes
the server to set a specific environment.

I don't know if it's necessary to mention this, but the fact that a clean
Debian installation will run gnome-keyring-daemon by default, and that
the manpage of gnome-keyring-daemon doesn't mention it's ssh-agent 
behaviour at all, makes it all worse.  Trying to find out which part of
the system was breaking ssh was quite an adventure, and I guess I would
have given up making ssh work again if I didn't know that ssh was working
on a lenny system using KDM instead if GDM.

Please fix before releasing lenny.  Or at least disable gnome-keyring-daemon
on default installations.

Thanks,
Bjorn

- -- System Information:
Debian Release: 5.0
  APT prefers testing
  APT policy: (700, 'testing'), (600, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.28-1-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages gnome-keyring depends on:
ii  gconf2                        2.22.0-1   GNOME configuration database syste
ii  libatk1.0-0                   1.22.0-1   The ATK accessibility toolkit
ii  libc6                         2.7-18     GNU C Library: Shared libraries
ii  libcairo2                     1.6.4-7    The Cairo 2D vector graphics libra
ii  libdbus-1-3                   1.2.1-5    simple interprocess messaging syst
ii  libgconf2-4                   2.22.0-1   GNOME configuration database syste
ii  libgcrypt11                   1.4.1-1    LGPL Crypto library - runtime libr
ii  libglib2.0-0                  2.16.6-1   The GLib library of C routines
ii  libgtk2.0-0                   2.12.11-4  The GTK+ graphical user interface 
ii  libhal-storage1               0.5.11-8   Hardware Abstraction Layer - share
ii  libhal1                       0.5.11-8   Hardware Abstraction Layer - share
ii  libpango1.0-0                 1.20.5-3   Layout and rendering of internatio
ii  libtasn1-3                    1.4-1      Manage ASN.1 structures (runtime)

Versions of packages gnome-keyring recommends:
ii  libpam-gnome-keyring          2.22.3-2   PAM module to unlock the GNOME key

gnome-keyring suggests no packages.

- -- no debconf information

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