Re: Re: dpkg behavior when following symlinks

[Guillem Jover <guillem@debian.org>]

On Fri, 2019-11-22 at 17:36:21 +0000, Alejandro Del Castillo wrote:
> I was pretty mystified on what's different...then I realized that the
> issue only happens when following symlinks on tmpfs (/tmp). Adding an
> extra directory (tmp) to the dpkg-test example reproduces the failure.
>
> At the end of the email, I have a patch that modifies the tests to show
> the failure (I tried attaching the patch to the email, but that made the
> list bot swallow my message).
>
> Is this a know issue or expected behavior?

Ok, the problem would be due to /proc/sys/fs/protected_symlinks being
set to 1.

So, I guess this is expected in the sense that letting [od]pkg write
into something with the properties of /tmp is insecure anyway, and
it should not be done. :)

Otherwise this is supported and should work.

Thanks,
Guillem