Christopher J. PeBenito wrote:
On Mon, 2007-05-07 at 15:03 -0400, Philip Tricca wrote:
Hello List,
Question about managing roles: I'm trying to setup my user to have
access to both the unprivileged user_r role and the administrative role
sysadm_r. My system is FC6 using the latest policy from yum:
[...]
I've created new SELinux user:
semanage user -a -R sysadm_r -R user_r -P user MyUser_u
I've associated a Linux user with my SELinux user:
semanage login -a -s MyUser_u MyUser
When I login with my new user I see ...
<shell>
[MyUser@test ~]$ id -Z
MyUser_u:user_r:user_t
[MyUser@test ~]$ newrole -r sysadm_r -t sysadm_t
Authenticating MyUser.
Password:
failed to exec shell
: Permission denied
[MyUser@test ~]$
</shell>
The initial role is user_r which I like. But when MyUser attempts to
change to the new role (sysadm_r through use of newrole)... they cannot.
<avc>
type=AVC msg=audit(1178544785.335:2418): avc: denied { transition }
for pid=13798 comm="newrole" name="bash" dev=hda3 ino=162298
scontex=MyUser_u:user_r:newrole_t:s0
tcontext=MyUser_u:sysadm_r:sysadm_t:s0 tclass=process
</avc>
[...]
A similar problem seems to arise when associating Linux users with
user_r, staff_r and sysadm_r. The user will login with the default
staff_r, will be able to newrole up to the sysadm_r role, but cannot
change their role to user_r through similar means (newrole -r user_r -t
user_t).
Allowed role changes are defined in the policy, and the stock policy
does not allow a change of staff_r <-> user_r or user_r -> sysadm_r.
I'd assume it's a fairly standard practice to make an SELinux user with
the user_r and sysadm_r roles
No, user_r is for generic unprivileged users. If you want an
unprivileged user that can change to the sysadm_r, you should be using
staff_r instead of user_r. User_r and staff_r basically have the same
rules except staff_r can change to sysadm_r, where user_r can't.
Excellent! I haven't ventured deep into the policy src yet, but a quick
grep on staff_r shows everything you describe quite clearly in the
policy/modules/system/userdomain files
After putting my user in staff_r & sysadm_r and relabeling my home dir
everything works as expected.
Thanks,
- Philip
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