[RFC][PATCH] selinux: Report result in avc messages

[Stephen Smalley]

I could make it permissive=0 or permissive=1 if that is less
confusing.  It doesn't necessarily correspond to the result of the
system call, just the avc_has_perm call, as e.g. the kernel checks
CAP_DAC_OVERRIDE and falls back to CAP_DAC_READ_SEARCH if only
read/search access was requested, and there are other cases where a
permission denial has a side effect rather than preventing the system
call (e.g. CAP_FSETID).

On Wed, Apr 30, 2014 at 6:34 AM, Daniel J Walsh <dwalsh at redhat.com> wrote:
>
> On 04/30/2014 09:29 AM, Steve Grubb wrote:
>> On Wednesday, April 30, 2014 08:59:50 AM Daniel J Walsh wrote:
>>> How about permitted rather then allowed.
>> I think permitted is already in an AVC.
> Not sure where.
>>
>>> On 04/29/2014 10:59 PM, Eric Paris wrote:
>>>> On Tue, 2014-04-29 at 16:54 -0700, Stephen Smalley wrote:
>>>>> Requested for Android in order to distinguish denials that are not in
>>>>> fact breaking anything yet due to permissive domains versus denials
>>>>> that are being enforced, but seems generally useful.  result field was
>>>>> already in the selinux audit data structure and was being passed to
>>>>> avc_audit() but wasn't being used.  Seems to cause no harm to ausearch
>>>>> or audit2allow to add it as a field.  Comments?
>>>> I think it's a great idea, but I'm worried that Steve is going to get
>>>> grumpy because an AVC record is going to have a result= field which is
>>>> similar, but not necessarily related to the res= field of a SYSCALL
>>>> record.
>> I think that I'll have to parse this field no matter what. Its probably that
>> important. In the syscall, we use success= to be the final determination.
>>
>>
>>>> Seems easily confused (although probably 9999 times out of
>>>> 10000 they will be the same)
>> Why would this ever not be correct? Are there times when we get an AVC with a
>> denial _and_ the syscall completes successfully?
>>
>> I'd suggest using res= since its in the audit dictionary and means exactly
>> what you are wanting to use it for. In it, 1 is success, 0 is failure.
>>
> I have seen AVC's where the success=yes in enforcing mode.  Basically
> the kernel takes a different code path and the syscall succeeds.  Most
> of these end up as dontaudits.
>>>> So while I wholeheartedly think we should take the idea, I wonder if
>>>> someone can dream up a name that isn't confusingly similar...
>>>>
>>>> I can't think of anything...
>> There is thesaurus.com. :-)
>>
>> consequence, outcome, effect, reaction,  conclusion, verdict, decision,
>> judgement, finding, ruling, answer, solution, recommendation, order,  ...
>>
>> -Steve
>