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From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To: Slawa Olhovchenkov <slw@zxy.spb.ru>
Subject: Re: OpenSSH, PAM and kerberos
References: <20130829004844.GA70584@zxy.spb.ru> <86d2ovy64p.fsf@nine.des.no>
 <20130830100926.GU3796@zxy.spb.ru> <20130830103009.GV3796@zxy.spb.ru>
Date: Fri, 30 Aug 2013 14:51:44 +0200
In-Reply-To: <20130830103009.GV3796@zxy.spb.ru> (Slawa Olhovchenkov's message
 of "Fri, 30 Aug 2013 14:30:09 +0400")
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Slawa Olhovchenkov <slw@zxy.spb.ru> writes:
> Dag-Erling Sm=C3=B8rgrav <des@des.no> writes:
> > PAM authentication in OpenSSH was broken for non-trivial cases when
> > privilege separation was implemented.  Fixing it properly would be
> > very difficult.
> Same behaviour with 'UsePrivilegeSeparation no'.  This issuse not in
> privilege separation, this is because PAM authentication use pthread
> emulation throw fork().

Please don't tell me how the code works.  I wrote it - or rather, I
wrote a version that worked, before the OpenSSH developers implemented
privilege separation and had to break the PAM integration code to make
it fit.  Even if you #define UNSUPPORTED_POSIX_THREADS_HACK to use
threads instead of a subprocess, OpenSSH will still call pam_start()
twice and lose the data stored in the authentication phase before
running the session phase.

(this is technically an abuse of the PAM API; I should probably add a
few lines to the OpenPAM dispatcher so it logs an error every time an
application tries to open a session without first authenticating)

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no