Martin Kosek wrote:
On 02/12/2014 09:33 PM, Josh wrote:


On Feb 12, 2014, at 3:20 PM, Rob Crittenden <rcrit...@redhat.com> wrote:

Josh wrote:

On Feb 11, 2014, at 2:52 PM, Rob Crittenden <rcrit...@redhat.com> wrote:

Josh wrote:

On Feb 11, 2014, at 2:44 PM, Rob Crittenden <rcrit...@redhat.com
<mailto:rcrit...@redhat.com>> wrote:

Josh wrote:
I have a situation where I need to support more than 1024 categories
on a system.  I modified the selinuxusermap.py file to check for the
number of categories I need but ipa still responds with the original
error message.  Do I need to restart any of the services?

Here is the command that was run and the output after applying the
patch below:

ipa config-mod
--ipaselinuxusermaporder='guest_u:s0$xguest_u:s0$user_u:s0$staff_u:s0-s15:c0.c16383$resadm_u:s0-s15:c0.c16383$ia_u:s0-s15:c0.c16383'
ipa: ERROR: invalid 'ipaselinuxusermaporder': SELinux user
'staff_u:s0-s15:c0.c16383' is not valid: Invalid MCS value, must
match c[0-1023].c[0-1023] and/or c[0-1023]-c[0-c0123]

Have you updated your SELinux policy to support a larger MCS range? If
not then this will get you past the IPA validator but it won't work
with SELinux. See semanage(8).

rob

Yes.  I’m trying to set the SELinux categories in freeipa because when
you have lots of categories all semanage commands slow down (way down).
  For other people’s knowledge, this requires recompilation of the
SELinux policy.

Ok, then your patch looks reasonable. The current code is for the default 
values and we haven't had cause to make this configurable before now. You might 
consider filing a ticket in our trac about this.

As it is for a very unique situation which most people won’t encounter I don’t 
think it’s worth making configurable.

Also note that this change will be lost on your next IPA upgrade, and you'll 
need to make this change on any IPA master you want these values to be managed. 
The data will remain unchanged, but the original python values will be restored 
if you update the packages.

I’m ok with that because the values only need to be set during initial setup.  
Any idea why the validator isn’t being modified?

I don't believe validators are currently extensible in the IPA framework. That 
might be something we need to look at as well.

regards

rob


Thanks for the help.

Sure. I'm glad we made at least obvious enough for you to be able to work 
around.

So I'm just curious about the need for this. You mentioned that semanage slows 
way down. Have you talked to the SELinux team about this? They've been quite 
responsive to our needs in the past, they may be able to fix something for you 
as well.

I’m not sure if my coworker has talked to them about it directly, no.  I’ll 
ping him to see if it’s something we want to get worked on moving forward.

On a more general note, we haven't had a lot of user feedback on the SELinux 
user map feature. Do you have any other suggestions on things we might do to 
improve it?

Nothing directly but I can describe how we’re using it and where some of the 
perceived pain points are.  Their impact is negligible though so we haven’t 
felt the need to investigate better ways to work around them.

We’ve got a network of systems running both targeted and MLS SELinux policy.  
What this means is that we must define both valid selinux context is the user 
map.  I.e. we define both staff_u:s0-s0:c0.c1023 and staff_u:s0-s15:c0.c1023 in 
the user map.  We then use host groups and multiple user maps to map 
appropriately.  Our commands might be easier to understand:

ipa config-mod 
--ipaselinuxusermaporder='guest_u:s0$xguest_u:s0$user_u:s0$staff_u:s0-s0:c0.c1023$staff_u:s0-s15:c0.c1023’
ipa hostgroup-add mls --desc="MLS SELinux Group”
ipa hostgroup-add-member mls --hosts=mlshost1,mlshost2
ipa hostgroup-add targeted --desc="Targeted SELinux Group”
ipa hostgroup-add-member targeted --hosts=appsrv1,appsrv2
ipa selinuxusermap-add staff_u  --selinuxuser=staff_u:s0-s0:c0.c1023
ipa selinuxusermap-add staff_u_MLS  --selinuxuser=staff_u:s0-s15:c0.c1023
ipa selinuxusermap-add-host staff_u --hostgroups=targeted
ipa selinuxusermap-add-host staff_u_MLS --hostgroups=mls
ipa selinuxusermap-add-user staff_u --groups=wheel
ipa selinuxusermap-add-user staff_u_MLS --groups=wheel

It might be more straightforward if we didn’t have to split the configuration 
like this but thanks to the flexibility of FreeIPA it’s very easy to do.

Thanks,
-josh

Nice. Not many of our users got back to us with experience on using the
advanced use of the SELinux feature - so feedback welcome!

Rob, I am wondering if it would make sense to extend the FreeIPA to allow
SELinux user map rules with more SELinux users, per policy? I.e. have a rule
like that:

# ipa selinuxusermap-show staff_u
   Rule name: staff_u
   SELinux User: staff_u:s0-s0:c0.c1023
   SELinux User (mls): staff_u:s0-s15:c0.c1023
   Enabled: TRUE
   User Groups: wheel
   Host Groups: selinuxhosts


This proposed rule structure is not ideal and would require updated IPA&SSSD on
all machines but it should explain the idea.

Martin


I think this would be handy if one had a lot of SELinux user categories but I don't think that is typical. Then again, I hadn't considered the case of different MLS levels either, so take it with a grain of salt.

rob

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