Re: plperl Safe restrictions

Andrew, can you or someone summarize were we left this issue and your
patch?

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Andrew Dunstan wrote:
>
>
> Tom Lane wrote:
>
> >Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> >
> >
> >>The question in my mind is "What are we protecting against?" ISTM it is
> >>the use of the pl as a vector to attack the machine and postgres. Does a
> >>segfault come into that category? After all, isn't it one of postgres's
> >>strengths that we can survive individual backends crashing?
> >>
> >>
> >
> >Yeah, but a repeatable segfault certainly is an adequate tool for a
> >denial-of-service attack, since it takes out everyone else's sessions
> >along with your own. A possibly larger objection is how sure can you be
> >that the effects will *only* be a segfault, and not say the ability to
> >execute some user-injected machine code.
> >
> >
>
> Ok, the release notes for perl 5.005 (which is now pretty ancient) say this:
>
> "Perl now contains its own highly optimized qsort() routine. The new
> qsort() is resistant to inconsistent comparison functions, so Perl's
> |sort()| will not provoke coredumps any more when given poorly written
> sort subroutines."
>
> Also, there were some apparent problems with sort routine reentrancy in
> perl < 5.6.1 - see
> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=60534.
>
> I have not found any more recent refs on Google to "sort" causing problems.
>
> Certainly in my testing it proved totally trivial to crash the backend
> with sprintf.
>
> So I suggest a reasonable position w.r.t. the danger of SEGVs would be
> to allow "sort" but disallow sprintf.
>
>
> cheers
>
> andrew
>
>
>
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