[SSSD] Re: What's the best way to debug SELinux issues on SSSD?

[Fabiano Fidêncio]

On Mon, May 21, 2018 at 10:32 PM, Jakub Hrozek <jhrozek(a)redhat.com&gt; wrote:
> > On 21 May 2018, at 21:39, Fabiano Fidêncio <fidencio(a)redhat.com&gt; wrote:
> >
> > People,
> >
> > I've been trying to debug a SELinux issue related to the domain
> > resolution order.
> >
> > Basically, if there's no domain_reoslution_order set:
> > [root@client1 vagrant]# ssh -l admin localhost
> > Password:
> > Last login: Mon May 21 19:00:06 2018 from ::1
> > [admin@client1 ~]$ id -Z
> > staff_u:staff_r:staff_t:s0-s0:c0.c1023
> >
> > But, if domain_resolution_order is set:
> > [root@client1 vagrant]# ssh -l admin localhost
> > Password:
> > Last login: Mon May 21 19:30:45 2018 from ::1
> > [[e-mail](a)client1 ~]$ id -Z
> > unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
>
>  Since sssd calls into libsemanage, then I would start with looking at the output of
> “semanage login -l”. 
You gave me this tip before, I did test it but I forgot to add details
about it :-/

The output is basically the same with or without domain_resolution_order set:

[root@client1 x86_64]# cat /etc/sssd/sssd.conf | grep domain_resolution_order
domain_resolution_order = foo
[root@client1 x86_64]# systemctl restart sssd
[root@client1 x86_64]# semanage login -l

Login Name           SELinux User         MLS/MCS Range        Service

__default__          unconfined_u         s0-s0:c0.c1023       *
admin                staff_u              s0-s0:c0.c1023       *
root                 unconfined_u         s0-s0:c0.c1023       *


[root@client1 x86_64]# vim /etc/sssd/sssd.conf
[root@client1 x86_64]# cat /etc/sssd/sssd.conf | grep domain_resolution_order
#domain_resolution_order = foo
[root@client1 x86_64]# systemctl restart sssd
[root@client1 x86_64]# semanage login -l

Login Name           SELinux User         MLS/MCS Range        Service

__default__          unconfined_u         s0-s0:c0.c1023       *
admin                staff_u              s0-s0:c0.c1023       *
root                 unconfined_u         s0-s0:c0.c1023       *


>  Is the context after selinux_child runs to completion set for admin
> or admin(a)ipa.example? 
In the selinux_child.log I can only see:
[[sssd[selinux_child[18149]]]] [unpack_buffer] (0x2000): username: admin

And it happens for both cases, with or without domain_resolution_order
being used.

>  Maybe libsemanage canonicalizes the name or UID with getpnam/uid and
> therefore uses the qualified name but because the provider has no sense of the
> domain_resolution_order, it calls sss_set_seuser() with the shortname? 
That's a good question. sss_set_seuser() hasn't been called, at all.

>
> Looking at whether we call sss_set_seuser() with the correct parameters might give
some hint as well.
>
>>
>> First thing that came to my mind was to take a look at
>> selinux_child.logs, but it didn't give me any clue as the logs are
>> exactly the same for both cases:
>>
>> No domain_resolution_order set:
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]] [main]
>> (0x0400): selinux_child started.
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]] [main]
>> (0x2000): Running with effective IDs: [0][0].
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]] [main]
>> (0x2000): Running with real IDs [0][0].
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]] [main]
>> (0x0400): context initialized
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [unpack_buffer] (0x2000): seuser length: 7
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [unpack_buffer] (0x2000): seuser: staff_u
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [unpack_buffer] (0x2000): mls_range length: 14
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [unpack_buffer] (0x2000): mls_range: s0-s0:c0.c1023
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [unpack_buffer] (0x2000): username length: 5
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [unpack_buffer] (0x2000): username: admin
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]] [main]
>> (0x0400): performing selinux operations
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [seuser_needs_update] (0x2000): getseuserbyname: ret: 0 seuser:
>> staff_u mls: s0-s0:c0.c1023
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [pack_buffer] (0x0400): result [0]
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]]
>> [prepare_response] (0x4000): r->size: 4
>> (Mon May 21 19:30:44 2018) [[sssd[selinux_child[23351]]]] [main]
>> (0x0400): selinux_child completed successfully
>>
>> domain_resolution_order set:
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]] [main]
>> (0x0400): selinux_child started.
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]] [main]
>> (0x2000): Running with effective IDs: [0][0].
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]] [main]
>> (0x2000): Running with real IDs [0][0].
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]] [main]
>> (0x0400): context initialized
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [unpack_buffer] (0x2000): seuser length: 7
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [unpack_buffer] (0x2000): seuser: staff_u
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [unpack_buffer] (0x2000): mls_range length: 14
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [unpack_buffer] (0x2000): mls_range: s0-s0:c0.c1023
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [unpack_buffer] (0x2000): username length: 5
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [unpack_buffer] (0x2000): username: admin
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]] [main]
>> (0x0400): performing selinux operations
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [seuser_needs_update] (0x2000): getseuserbyname: ret: 0 seuser:
>> staff_u mls: s0-s0:c0.c1023
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [pack_buffer] (0x0400): result [0]
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]]
>> [prepare_response] (0x4000): r->size: 4
>> (Mon May 21 19:31:36 2018) [[sssd[selinux_child[23398]]]] [main]
>> (0x0400): selinux_child completed successfully
>>
>> Taking a look at the IPA provider, logs also do like the very same:
>> https://paste.fedoraproject.org/paste/FKhvxyj3clzXuE5C7tMGhw (pastebin
>> is huge!)
>>
>> Some tip on which logs I could take a look and/or part of the code I
>> could instrument in order to, at least, get some directions?
>>
>> Thanks in advance,
>> --
>> Fabiano Fidêncio
>> _______________________________________________
>> sssd-devel mailing list -- sssd-devel(a)lists.fedorahosted.org
>> To unsubscribe send an email to sssd-devel-leave(a)lists.fedorahosted.org
>> Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html
>> List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
>> List Archives:
https://lists.fedoraproject.org/archives/list/[e-mail]...
> _______________________________________________
> sssd-devel mailing list -- sssd-devel(a)lists.fedorahosted.org
> To unsubscribe send an email to sssd-devel-leave(a)lists.fedorahosted.org
> Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html
> List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
> List Archives:
https://lists.fedoraproject.org/archives/list/[e-mail]...