On 2017-04-11 15:36, Paul Moore wrote:

On Wed, Mar 29, 2017 at 6:29 AM, Richard Guy Briggs [off-list ref] wrote:

quoted

On 2017-03-09 09:34, Steve Grubb wrote:

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On Tuesday, March 7, 2017 4:10:49 PM EST Richard Guy Briggs wrote:

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one possibly audit-worth case which (if I read correctly) this will
skip is where a setuid-root binary has filecaps which *limit* its
privs.
Does that matter?

I hadn't thought of that case, but I did consider in the setuid case
comparing before and after without setuid forcing the drop of all
capabilities via "ambient".  Mind you, this bug has been around before
Luto's patch that adds the ambient capabilities set.

Can you suggest a scenario where that might happen?

Sorry, do you mean the case I brought up, or the one you mentioned?  I
don't quite understnad the one you brought up.  For mine it's pretty
simple to reproduce, just

I was talking about the case you brought up, but they could be the same
case.

I was thinking of a case where the caps actually change, but are
overridden by the blanket full permissions of setuid.

If there actually is a change in capability bits besides the implied change of
capabilities based on the change of the uid alone, then it should be logged.

Are you speaking of a change in pP' only from pI, or also pI', pE' and pA'?

Something like ( pP' xor pI ) not empty?

The previous patch I'd sent was reasonably easy to understand, but I'm
having trouble adding this new twist to the logic expression in question
due to the inverted combination of pre-existing items.  I'm having
trouble visualizing a 5 or more-dimensional Karnaugh map...

While I am at it, I notice pA is missing from the audit record.  The
record contains fields "old_pp", "old_pi", "old_pe", "new_pp", "new_pi",
"new_pe" so in keeping with the previous record normalizations, I'd like
to change the "new_*" variants to simply drop the "new_" prefix.

        https://github.com/linux-audit/audit-kernel/issues/40

Yes, there is the separate ambient capabilities record patch, but
where do we stand with this patch?  From what I gather there is still
some uncertainty here?

Yes, I put this on my back burner thinking about how best to re-approach
this, hoping others would offer some insight or advice how to attack
this, otherwise I'm going to end up with a horrendous conditional
expression, I fear.

Steve, I was hoping to get a clarification from you about which
capability bits had changed.

Serge, do you have any suggestions on how to approach the conditional
logic?

paul moore

- RGB

--
Richard Guy Briggs [off-list ref]
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635
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