Date: Thu, 08 Dec 2011 12:47:56 -0700 From: Kurt Seifried <kseifried@...hat.com> To: oss-security@...ts.openwall.com CC: Jeff Mitchell <mitchell@....org> Subject: Re: Disputing CVE-2011-4122 On 12/08/2011 07:11 AM, Jeff Mitchell wrote: > On 12/07/2011 11:26 AM, Kurt Seifried wrote: >>> One could assume that kcheckpass should do the validation. However, the >>> PAM documentation makes no mention of what a service name is supposed to >>> look like, and consequently it must be treated as opaque by the >>> application code. Therefore all validation must be expected to be done >>> by the library, and failure to do so must be seen as a bug in the >>> library exclusively. >> >> Can you provide a link to the documentation? > > http://pubs.opengroup.org/onlinepubs/8329799/pam_start.htm > > Thanks, > Jeff > Looking around I did find: http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/3/html/Reference_Guide/s1-pam-config-files.html ===================== 15.2.1. PAM Service Files Each PAM-aware application or service has a file within the /etc/pam.d/ directory. Each file within this directory bears the name of the service for which it controls access. It is up to the PAM-aware program to define its service name and install its own PAM configuration file in the /etc/pam.d/ directory. For example, the login program defines its service name as login and installs the /etc/pam.d/login PAM configuration file. ===================== so to some degree it is defined: the service name must fit legal file name constraints, but this means things like length, but on ext4 for example this means 256 chars max, and only NULL and "/" are disallowed, to say nothing of other file systems like xfs (any bytes except null) and Joliet (CDFS, max 64 characters, unicode supported) So perhaps going for a lowest common denominator of common filesystems you'd expect to find /etc/ on (so ext4, xfs, maybe Joliet for cd based systems?) as a filter would be appropriate? And poking the PAM people to refine the specification a little bit? Thoughts or comments anyone?  http://en.wikipedia.org/wiki/Comparison_of_file_systems -- -Kurt Seifried / Red Hat Security Response Team
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