On 03/22/2010 03:51 PM, Andy Warner wrote:
On 3/22/2010 3:22 PM, Daniel J Walsh wrote:
On 03/22/2010 03:14 PM, Andy Warner wrote:
Using FC12, fully updated. I have two basic,
but
possibly related questions. The first is regarding a change to the
targeted policy that resulted in an install error for our Trusted RUBIX
policy when using the userdom_unpriv_user_template interface, as off the last targeted policy update. The
second are denials I now receive after changing our policy to use a
different interface.
First issue:
Our policy had been declaring a custom role (rubix_dbadm_r in this
case) using the following:
userdom_unpriv_user_template(rubix_dbadm)
corecmd_exec_shell(rubix_dbadm_t)
Originally, this worked for its intended purposes with no selinux
denials. As of installing policy update:
Name : selinux-policy-targeted
Arch : noarch
Version : 3.6.32
Release : 103.fc12
When we build our policy we received the following errors:
rubix-dev.te:175: Warning: xserver_user_client() has been deprecated,
please use xserver_user_x_domain_template instead.
Installing rubix-dev-targeted policy
libsepol.print_missing_requirements: rubix-dev's global requirements
were not met: type/attribute xdrawable_type (No such file or directory).
libsemanage.semanage_link_sandbox: Link packages failed (No such file
or directory).
semodule: Failed!
Looks like a bug in the interface, You can probably hand edit it, to
remove the requirement for xdrawable_type.
I believe there are other unmet requirements as well. Also, this will
be an issue for the users of Trusted RUBIX. I would rather not request
that they hand edit portions of the non-RUBIX policy. So, if it works
properly, I would rather just use userdom_restricted_user_template
(or
should it be userdom_base_user_template?).
I had
been receiving the depreciated warning a while (ignoring at my
own peril), the link error was new to this targeted policy version. I
also received errors while installing selinux-policy-targeted rpm
itself, stating a different requirement not being met in the then
installed rubix-dev policy. I do not recall the exact error message,
but remember it was an X related type that was missing.
Noting the X connection between the depreciated function and the link
error, I traced the reference to the depreciated 'xserver_user_client'
interface to 'userdom_unpriv_user_template'. I did
not call 'xserver_user_client' directly. I replaced the call to
'userdom_unpriv_user_template' with a call
to 'userdom_restricted_user_template' and my then
policy installed properly.
But using the 'userdom_restricted_user_template ' interface,
now
I
notice
some
selinux denials during a call to newrole, which is my
second question below. I am not sure that the change to the new
interface is the cause of the denials, I am just now noticing them.
Should the 'userdom_unpriv_user_template' interface
either be fixed or removed from the userdom *.if file?
Second issue:
The rubix_dbadm_r role is now created with:
userdom_restricted_user_template(rubix_dbadm)
corecmd_exec_shell(rubix_dbadm_t)
When I perform a newrole, I receive denials as follows (note, I am in
permissive mode so the newrole succeeds):
$ id -Z
rxdev_u:staff_r:staff_t:s0-s0:c0.c1023
$ ls -Z `tty`
crw--w----. warner tty rxdev_u:object_r:user_devpts_t:s0 /dev/pts/4
$ newrole -r rubix_dbadm_r
Password:
$
Note: I am a bit surprised that the tty type is user_devpts_t and not staff_devpts_t,
though
I
am
very
unfamiliar with this.
Mar 22 11:04:03 localhost setroubleshoot: SELinux is preventing
/usr/bin/newrole "write" access on /var/run/dbus/system_bus_socket. For
complete SELinux messages. run sealert -l
95fc56ee-8711-460c-874b-6ddb91cc9add
Mar 22 11:04:03 localhost setroubleshoot: SELinux is preventing
/usr/bin/newrole "write" access on /var/run/dbus/system_bus_socket. For
complete SELinux messages. run sealert -l
95fc56ee-8711-460c-874b-6ddb91cc9add
These look like a bug in policy. Something in the pam stack is trying
to communicate with dbus and newrole is not allowed this access. What
do the AVC messages look like.
Here are the AVC's I get which seem related to the newrole usage:
type=AVC msg=audit(1269286396.529:155): avc: denied { write } for
pid=5636 comm="newrole" name="system_bus_socket" dev=dm-0 ino=153
scontext=rxdev_u:staff_r:newrole_t:s0-s0:c0.c1023
tcontext=system_u:object_r:system_dbusd_var_run_t:s0 tclass=sock_file
type=AVC msg=audit(1269286396.529:155): avc: denied { connectto }
for pid=5636 comm="newrole" path="/var/run/dbus/system_bus_socket"
scontext=rxdev_u:staff_r:newrole_t:s0-s0:c0.c1023
tcontext=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023
tclass=unix_stream_socket
type=USER_AVC msg=audit(1269286396.540:156): user pid=1003 uid=81
auid=4294967295 ses=4294967295
subj=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 msg='avc: denied
{ send_msg } for msgtype=method_call interface=org.freedesktop.DBus
member=Hello dest=org.freedesktop.DBus spid=5636
scontext=rxdev_u:staff_r:newrole_t:s0-s0:c0.c1023
tcontext=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 tclass=dbus :
exe="/bin/dbus-daemon" sauid=81 hostname=? addr=? terminal=?'
type=USER_AVC msg=audit(1269286396.563:157): user pid=1003 uid=81
auid=4294967295 ses=4294967295
subj=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 msg='avc: denied
{ send_msg } for msgtype=method_call
interface=net.reactivated.Fprint.Manager member=GetDefaultDevice
dest=net.reactivated.Fprint spid=5636 tpid=5640
scontext=rxdev_u:staff_r:newrole_t:s0-s0:c0.c1023
tcontext=system_u:system_r:fprintd_t:s0-s0:c0.c1023 tclass=dbus :
exe="/bin/dbus-daemon" sauid=81 hostname=? addr=? terminal=?'
type=USER_AVC msg=audit(1269286396.567:158): user pid=1003 uid=81
auid=4294967295 ses=4294967295
subj=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 msg='avc: denied
{ send_msg } for msgtype=error
error_name=net.reactivated.Fprint.Error.NoSuchDevice dest=:1.131
spid=5640 tpid=5636 scontext=system_u:system_r:fprintd_t:s0-s0:c0.c1023
tcontext=rxdev_u:staff_r:newrole_t:s0-s0:c0.c1023 tclass=dbus :
exe="/bin/dbus-daemon" sauid=81 hostname=? addr=? terminal=?'
# more securetty_types
sysadm_tty_device_t
user_tty_device_t
staff_tty_device_t
user_devpts_t
devpts_t
#
Are these denials related to how I create the rubix_dbadm_r role? Is
there a proper way to create a role suitable for auser to transition
into and as a potential default logon user role?
I fully admit my choice of creating a role was through observation of
other policy code and trail and error. It would be nice to have a
definitive word on it.
Thanks,
Andy
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Do you want rubix_dbadm_t to be a full login user
or just the domain to run with when you are root?
Trusted RUBIX implements SELinux within our DBMS objects and
administrative programs. Similar to SEPostgreSQL
We want it to be a full login user, if possible. Bare minimum is to be
able to open a shell as the rubix_dbadm_t, typically transitioning from
staff_r. Actually, the role has more associated with it than just
rubix_dbadm_t. This role is configured to run administrative programs
on behalf of our DBMS. It is also configured to run DBMS sessions with
special privilege.
I am suggesting you open a bugzilla on this but hand edited to be able
to continue your work. Patches to fix the interface problem would be
helpful. If your goal is to get this to work on RHEL6 you might want
to start working with the F13 policy.
I am not
sure of the reference to root. But, root is not a factor in
this. In becoming/using our rubix_dbadm_r role (or any of our DBMS
roles, the user should not become nor need to transition through the
linux root user.
If you want to allow full use of a desktop but only allow
certain privs
as root, I would use staff_t and then transition through sudo to
rubix_dbadm_t. Setup an SELinux user that logs in as staff_t and has
the staff_r, rubix_dbadm_r and system_r (If he needs to restart
services).
It is more than just restart services. This is a fundamental role
within the Trusted RUBIX RBAC. For instance, we have DBMS Security
Administrator, Audit Administrator, Operator, and User roles. All with
various abilities to run Trusted RUBIX administrative programs and all
with differing privilege with regards to a DBMS session.
Ok sounds good. I think the userdom_restricted_user_template
is what you want for your other roles. Since this is the least
privileged user.
Thanks
for your help,
Andy
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