On 08/08/2013 09:35 AM, Andy Lutomirski wrote: > On Wed, Aug 7, 2013 at 6:30 PM, Chen Gang <[email protected]> wrote: >> On 08/08/2013 12:58 AM, Andy Lutomirski wrote: >>> On Wed, Aug 7, 2013 at 9:21 AM, Oleg Nesterov <[email protected]> wrote: >>>> On 08/06, Andy Lutomirski wrote: >>>>> >>>>> I assume that what the man page means is that the return value is >>>>> whatever fsgid was prior to the call. On error, fsgid isn't changed, so >>>>> the return value is still "current". >>>> >>>> Probably... Still >>>> >>>> On success, the previous value of fsuid is returned. >>>> On error, the current value of fsuid is returned. >>>> >>>> looks confusing. sys_setfsuid() always returns the old value. >>>> >>>>> (FWIW, this behavior is awful and is probably the cause of a security >>>>> bug or three, since success and failure are indistinguishable. >>>> >>>> At least this all looks strange. >>>> >>>> I dunno if we can change this old behaviour. I won't be surprized >>>> if someone already uses setfsuid(-1) as getfsuid(). >>> >> >> Oh, really it is. >> >> Hmm... as a pair function, we need add getfsuid() too, if we do not add >> it, it will make negative effect with setfsuid(). >> >> Since it is a system call, we have to keep compitable. >> >> So in my opinion, better add getfsuid2()/setfsuid2() instead of current >> setfsuid() > > How about getfsuid() and setfsuid2()? >
Hmm... I have 2 reasons, please check. 1st reason: I checked history (just like Kees Cook suggested), getfsuid() is mentioned before (you can google to find it), so need use getfsuid2() to bypass the history complex. And 2nd reason: getfsuid() seems more like the pair of setfsuid(), not for setfsuid2(). > --Andy > > Thanks. -- Chen Gang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
