error: ssh_selinux_getctxbyname: Failed to get default SELinux security context

[Daniel J Walsh]

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On 09/30/2010 07:37 AM, imsand at puzzle.ch wrote:
>>> On 28/09/10 16:10, imsand at puzzle.ch wrote:
>>>>> On 28/09/10 15:08, Daniel J Walsh wrote:
>>>>>>>>>>> What's wrong on my system?
>>>>>>>>>>> Why it's not possible to login even if selinux is in permissive
>>>>>>>>>>> mode?
>>>>>>>>>>> Any suggestions?
>>>>>>>>>>
>>>>>>>>>> I'd start by trying to figure out why sshd isn't running in
>>>>>>>>>> sshd_t
>>>>>>>>>> (it
>>>>>>>>>> seems to be running in sysadm_t).
>>>>>>>>>>
>>>>>>>>>> Paul.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Yes, sshd is running in sysadm_t:
>>>>>>>>>
>>>>>>>>> # ps axZ | grep sshd
>>>>>>>>> system_u:system_r:sysadm_t       3632 ?        Ss     0:00
>>>>>>>>> /usr/sbin/sshd
>>>>>>>>> -o PidFile=/var/run/sshd.init.pi
>>>>>>>>>
>>>>>>>>> # ls -Z /usr/sbin/sshd
>>>>>>>>> system_u:object_r:sshd_exec_t /usr/sbin/sshd
>>>>>>>>>
>>>>>>>>> Don't know why it's not sshd_t. I didn't modified something. It's
>>>>>>>>> a
>>>>>>>>> standard installation of sles11 with the default reference policy
>>>>>>>>> from
>>>>>>>>> tresys.
>>>>>>>>>
>>>>>>>>> Maybe this code snippet from policy/modules/services/ssh.te is
>>>>>>>>> responsible
>>>>>>>>> for that:
>>>>>>>>> ##<desc>
>>>>>>>>> ##<p>
>>>>>>>>> ## Allow ssh logins as sysadm_r:sysadm_t
>>>>>>>>> ##</p>
>>>>>>>>> ##</desc>
>>>>>>>>> gen_tunable(ssh_sysadm_login, true)
>>>>>>>>>
>>>>>>>>> Any ideas?
>>>>>>>>
>>>>>>>> Do you have boolean init_upstart set to on? if not try setting it
>>>>>>>> to
>>>>>>>> on.
>>>>>>>> I do not believe ssh_sysadm_login boolean works currently but i may
>>>>>>>> be
>>>>>>>> mistaken.
>>>>>>>
>>>>>>> Yeah, setting init_upstart to on did the trick! THANK A LOT!
>>>>>>> Do you know why this prevents the user from logging in through ssh
>>>>>>> even
>>>>>>> if
>>>>>>> selinux is set to permissive??
>>>>>>>
>>>>>> Probably a bug in pam_selinux or sshd if it does not use pam_selinux.
>>>>>> Something is not respecting the permissive mode flag.  Of course you
>>>>>> are
>>>>>> asking about sles on the Fedora mailing list.. :^)
>>>>>
>>>>> You'd see the same problem in Fedora if sshd wasn't running in sshd_t.
>>>>> The SSH server tries to compute the correct context for the session,
>>>>> fails, and bails out even in permissive mode. I saw this happen in the
>>>>> curl test suite, where we start an SSH server and try connecting to
>>>>> it.
>>>>>
>>>>> Paul.
>>>>>
>>>> After setting init_upstart = on sshd runs in sshd_t.
>>>> Do you know why? Can't sshd do a domain transition if init_upstart is
>>>> disabled?
>>>
>>> There's more on this here:
>>>
>>> https://bugzilla.novell.com/show_bug.cgi?id=582399
>>>
>>> Paul.
>>> --
>> Thank you for the link. I rename "/etc/initscript" like described it the
>> report. now, sshing is working in both cases (init_upstart = on | off).
>> Thats fine.
>> But the role transition still not work.
>>
>>
>> --
>> selinux mailing list
>> selinux at lists.fedoraproject.org
>> https://admin.fedoraproject.org/mailman/listinfo/selinux
>>
> 
> I found out that the role transition works when the linux user name is
> equivalent to the SELinux name (both are mat_u).
> If so, the default user context after login via ssh is:
> "context=mat_u:staff_r:staff_t"
> And the explicit role transition to sysadm_r works as desired:
> "newrole -r sysadm_r" results in  "context=mat_u:sysadm_r:sysadm_t".
> 
> So far as I see, the user mapping seems to be correct:
> semanage login -l | grep mat
> Login Name                SELinux User
> mat                       mat_u
> 
> When I rename the Linux Login name back to mat, the role transition don't
> work anymore and the SELinux context switches back to
> "user_u:user_r:user_t" which is the default context if no correspond user
> is found by SELinux.
> 
> Do I miss something?
> 
> 
> --
> selinux mailing list
> selinux at lists.fedoraproject.org
> https://admin.fedoraproject.org/mailman/listinfo/selinux
> 
> 
Are you the guy on SLES?  Or Fedora?  In the old days pam_selinux and
libselinux used to not map Linux Users to SELinux users.  So you had to
create a SELinux user for every user.  You may be using an older version
of the code.
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