Re: transition from init_rc

[Douglas Brown]

The refpolicy has the following mcs constraints:


# New filesystem object labels must be dominated by the relabeling subject
# clearance, also the objects are single-level.
mlsconstrain file { create relabelto }
        (( h1 dom h2 ) and ( l2 eq h2 ));


mlsconstrain { dir file lnk_file chr_file blk_file sock_file fifo_file } { create
relabelto }
        (( h1 dom h2 ) and ( l2 eq h2 ));

There's no "or ( t1 != mcs_constrained_type)" for the relabelto of files
(unlike other constraints in the mcs policy), so I don't think there can be an
attribute to allow a domain to override the constraint. Perhaps you could look into
transitioning initrc_t to a different domain with system_high clearance, which can then do
what you need it to?

Cheers,
Doug

On 12 Nov 2015, at 9:36 AM, Tracy Reed
<[e-mail]<mailto:[e-mail]>> wrote:

dgrift suggested on IRC that I try the domain_obj_id_change_exemption attribute.

I tried that and it didn't work. For example I added the following (including
trying the extra unnecessary attributes):

# Adding lines to try and overcome the constraint violation for initrc starting nodes.
domain_obj_id_change_exemption(initrc_t)
domain_subj_id_change_exemption(initrc_t)
domain_role_change_exemption(initrc_t)
domain_system_change_exemption(initrc_t)
domain_user_exemption_target(initrc_t)

# Guess this really shouldn't be necessary, but just in case.
allow initrc_t myapp_exec_t:file execute;
allow initrc_t myapp_java_t:file { execute read execmod open getattr execute_no_trans };
allow initrc_t myapp_java_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_api_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_bin_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_conf_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_exec_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_lib_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_logs_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_nodes_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_release_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_scripts_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_util_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_var_t:file { relabelfrom relabelto getattr };
allow initrc_t myapp_webapps_t:file { relabelfrom relabelto getattr };

Policy loads, but on reboot when the init.d starts the web application:

type=AVC msg=audit(1447281933.532:76): avc:  denied  { relabelto } for  pid=1429
comm="chcon" name="select2_doctype.css" dev=dm-0 ino=614732
scontext=system_u:system_r:initrc_t:s0 tcontext=myapp_u:object_r:myapp_webapps_t:s0:c18
tclass=file
type=AVC msg=audit(1447281933.607:77): avc:  denied  { relabelto } for  pid=1429
comm="chcon" name="myapp-release" dev=dm-0 ino=508002
scontext=system_u:system_r:initrc_t:s0 tcontext=myapp_u:object_r:myapp_release_t:s0:c18
tclass=file
type=AVC msg=audit(1447281933.936:78): avc:  denied  { relabelto } for  pid=1429
comm="chcon" name="README" dev=dm-0 ino=1296427
scontext=system_u:system_r:initrc_t:s0 tcontext=myapp_u:object_r:myapp_logs_t:s0:c18
tclass=file

Still getting the constraint messages.
#!!!! This avc is a constraint violation.  You will need to add an attribute to either the
source or target type to make it work.
#Contraint rule:
allow initrc_t myapp_logs_t:file relabelto;

Ideas?

On Tue, Nov 10, 2015 at 03:48:35PM PST, Tracy Reed spake thusly:
Hello all!

Way back in May I wrote to the list and got some, but not all, of the problems
fixed in my policy. This project was on the back-burner mostly working for a
while but now I need to get it perfected.

We use MCS and have an automated process to deploy web application instances to
machines with a separate category per application instance to protect them from
each other. When the application starts the init script does a chcon to set the
category/context. initrc_t is supposedly unconstrained from what I'm reading in
the docs so why is it being prohibited from relabeling?

type=AVC msg=audit(11/09/2015 04:22:43.045:3126812) : avc: denied { relabelto }
for pid=13753 comm=chcon name=tomcat-server.xml dev=dm-0 ino=16900514
scontext=system_u:system_r:initrc_t:s0
tcontext=myapp_u:object_r:myapp_conf_t:s0:c50 tclass=file

On Tue, May 26, 2015 at 02:04:59AM PDT, Tracy Reed spake thusly:
#!!!! This avc is a constraint violation.  You will need to add an attribute to either the
source or target type to make it work.
#Contraint rule:
allow initrc_t default_t:file relabelto;

#!!!! This avc is a constraint violation.  You will need to add an attribute to either the
source or target type to make it work.
#Contraint rule:
allow initrc_t myapp_api_t:file relabelto;

The init script which starts the service relabels the files when the service
starts. I suspect this is a bad idea and I'm not sure why they are doing it. I
think they may be applying security categories here. We may have to find a
different way to approach that.

But how would I allow this if I wanted to?

Similarly:

#!!!! This avc is a constraint violation.  You will need to add an attribute to either the
source or target type to make it work.
#Contraint rule:
allow setfiles_t default_t:file relabelfrom;

#!!!! This avc is a constraint violation.  You will need to add an attribute to either the
source or target type to make it work.
#Contraint rule:
allow setfiles_t myapp_api_t:file relabelfrom;

etc...

This is all on CentOS 6.5.

--
Tracy Reed



--
selinux mailing list
[e-mail]<mailto:[e-mail]>
https://admin.fedoraproject.org/mailman/listinfo/selinux

--
selinux mailing list
[e-mail]<mailto:[e-mail]>
https://admin.fedoraproject.org/mailman/listinfo/selinux