[Bug 881] PAM: authentication thread exited unexpectedly

bugzilla-daemon at mindrot.org bugzilla-daemon at mindrot.org
Fri Jun 18 06:15:26 EST 2004


http://bugzilla.mindrot.org/show_bug.cgi?id=881

           Summary: PAM: authentication thread exited unexpectedly
           Product: Portable OpenSSH
           Version: 3.8p1
          Platform: UltraSparc
        OS/Version: Solaris
            Status: NEW
          Severity: normal
          Priority: P2
         Component: PAM support
        AssignedTo: openssh-bugs at mindrot.org
        ReportedBy: a at wynes.com
                CC: a at wynes.com


Relevant components of our environment:

	Solaris 8
	Sun Resource Manager 1.3 (SRM) with all published patches.
	OpenSSH 3.8.1p1

We're having an issue where SSH logins using PAM authentication are
failing for certain accounts (those without SRM lnodes).  The client 
receives a "Connection Closed" message and sshd logs the message "fatal: PAM:
authentication thread exited unexpectedly".

With SRM, the kernel uses lnodes (Limit nodes) associated with uids to 
track usage and allocation for RAM, CPU and logins.  

An lnode can be created manually after the userid has been created or
automatically the first time a user logs in.  This is done by a PAM
module - pam_srm.

	http://docs.sun.com/db/doc/816-7750/6mdo1u7fr?q=pam_srm&a=view

If the account logging in does not have an lnode, the module runs a script
/etc/srm/nolnode to generate one. SSH is exiting as a result of calling this 
PAM module - if I comment out that PAM module the user can log in. lnodes are
only created once, unless deleted by root.

Observations:

o If the user has an existing lnode, they can log in fine.
o This functionality worked with OpenSSH 3.7.1p1.
o If UsePassword or RSAAuthentication are used instead of PAM the users can log
in fine.
o We use PrivilegeSeparation. It happens if that is turned off/on.
o The /etc/srm/nolnode script is never running - I've made changes to verify.
o The logins succeed if pam_srm is commented out in pam.conf.  That's our
work-around but it means those logins are not controlled by SRM.

This looks like a bug with SRM but I don't understand why it wasn't an
issue with OpenSSH 3.7.1p1. If it's obviously a problem with pam_srm
can you tell me what it would be doing to cause sshd to log the "exited
unexpectedly" message.  A SEGFAULT?

Thanks.



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