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Re: [Libtirpc-devel] Fwd: Re: proposed patch to rpcbind to providefiner-grained security controls than offered by the -i option
On Sat, Dec 18, 2010 at 6:44 PM, Jeff Layton <jlayton@redhat.com> wrote:
> On Sat, 18 Dec 2010 18:01:42 -0500
> Chuck Lever <chucklever@gmail.com> wrote:
>>
>> Jeff will probably remember exactly why we did this, but I seem to
>> recall that the application that was crashing didn't like the
>> truncation solution either. ?I could be misremembering. ?We'll have to
>> check in with that bug again to ensure we don't introduce a
>> regression.
>>
>> I'll post a more-or-less official patch for this later, and see if I
>> can hook up with Jeff to find out more.
>>
>
> Actually, I originally proposed a fix similar to what Andrew is
> suggesting. Peter objected and said that returning NULL was more
> correct.
>
> The original problem was that umount.nfs was crashing (due to the
> abort() calls), so we ended up fixing it to use setgroups to drop
> supplimentary groups since it was not needed for umounts anyway. I also
> removed those abort calls from the library.
It sounds like it shouldn't cause any problems for umount.nfs to
truncate the supplemental groups list in the libtirpc library, just as
glibc does.
> I can see arguments for either way. On the one hand, people porting to
> libtirpc are likely to be fixing code anyway -- fixing this ought to be
> doable at the same time. It's really not hard to call setgroups to fix
> up the groups list before you call this function.
The application should deal with this before the call anyway, IMO.
That way it can detect the issue, intervene if needed, and warn and
quit if it can't handle the truncation.
> OTOH, adopting glibc's behavioe might ease the transition, even if it
> is a hack that might lead to unreliable application behavior.
It seems to me that it has been adequately demonstrated that group
list truncation is appropriate behavior for this interface.
--
"What is a pancake, if not a big, fluffy Eucharist?"
?-- Stephen Colbert