[krbdev.mit.edu #2577] [Russ Allbery] Bug#250966: /usr/sbin/klogind: Authorization behavior not fully documented

[Sam Hartman via RT]

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Subject: Bug#250966: /usr/sbin/klogind: Authorization behavior not fully
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Reply-To: Russ Allbery <rra at stanford.edu>, 250966 at bugs.debian.org
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From: Russ Allbery <rra at stanford.edu>
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Package: krb5-rsh-server
Version: 1.3.3-1
Severity: normal
File: /usr/sbin/klogind
Tags: security

(Apologies if the security tag was inappropriate; I don't consider this
to be a major security hole or anything, but it does raise a security
issue, which was reportbug's definition.)

If klogind is used and configured with a default realm, and someone with
a user principal in that realm attempts to log on to an account that does
not have a .k5login file at all, that login appears to be authorized.
This may be somewhat surprising if one is not following the same namespace
as the Kerberos realm klogind is using, since the man page doesn't say
this and sort of implies that .k5login is always checked.

Ideally, it would be nice to have a switch to klogind that says "always
deny authorization if no .k5login file is present," but at the least I
think this should probably be documented in the klogind man page.

Note that this also isn't documented in the .k5login man page.

-- System Information:
Debian Release: testing/unstable
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable')
Architecture: i386 (i686)
Kernel: Linux 2.4.26
Locale: LANG=C, LC_CTYPE=C (ignored: LC_ALL set to C)

Versions of packages krb5-rsh-server depends on:
ii  krb5-config                 1.6          Configuration files for Kerberos V
ii  libc6                       2.3.2.ds1-12 GNU C Library: Shared libraries an
ii  libcomerr2                  1.35-6       The Common Error Description libra
ii  libkrb53                    1.3.3-1      MIT Kerberos runtime libraries
ii  netbase                     4.16         Basic TCP/IP networking system

-- no debconf information