Re: Can unprivileged users corrupt the store with bad tarballs?

[Mark H Weaver <mhw@netris.org>]

ludo@gnu.org (Ludovic Courtès) writes:

> Mark H Weaver <mhw@netris.org> skribis:
>
>> I was thinking about the security implications of giving out shell
>> access to one of my systems running Guix.
>>
>> When I ask guix-daemon to build package 'foo', it will use as an input
>> the source for package 'foo', usually a tarball.  If the tarball is
>> already in the store, it won't download it again, because it is
>> effectively cached in the store.
>>
>> It is possible for another user on the same system to corrupt the cache,
>> but manually adding a bad tarball for 'foo' to the store, in such a way
>> that it would be used to build 'foo' when I ask for it?
>
> No.
>
> Tarballs are fixed-output derivations, so the hash of the tarball is
> known in advance.  Thus, when building a package, you’re sure to use the
> tarball whose hash is in the recipe.

What about things that aren't fixed-output derivations?  Are the results
of 'origin' forms with included patches or snippets "fixed-output"?

Could an unprivileged user add one of these to the store that wasn't
authentic?

     Mark