[PATCH] Error checking for SETXID (bug 13347)

[Florian Weimer]

On 03/24/2014 04:32 PM, Rich Felker wrote:
> On Mon, Mar 24, 2014 at 03:19:59PM +0000, Joseph S. Myers wrote:
>> On Mon, 24 Mar 2014, Florian Weimer wrote:
>>
>>> Check for syscall error in the SETXID implementation in NPTL (bug 13347).
>>>
>>> At this point, we can only abort the process because we have already switched
>>> credentials on other threads.  Returning an error would still leave the
>>> process in an inconsistent state.
>>
>> This may be the best possible in the absence of a kernel interface for
>> setting ids atomically for the whole process, but such an interface would
>> be the desired long-term fix, with aborting from the present code just a
>> fallback - is there ongoing work to agree such an interface?
>
> Are you sure you can't make it so that all setuid calls but the first
> can't fail?

We already are in this situation if application only ever uses the 
SETXID wrappers, I think.  That's why the test has to resort to directly 
invoking the syscall.

-- 
Florian Weimer / Red Hat Product Security Team