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Re: Reducing the attack surface caused by Berkeley DB...




On Fri, Jan 26, 2018 at 11:39:29AM +0100, David Kalnischkies wrote:
> On Thu, Jan 25, 2018 at 11:59:06PM +0100, Lionel Debroux wrote:
> > In practice, Berkeley DB is a core component of most *nix distros.
> > Debian popcon indicates that libdb5.3 is installed on ~80% of the
> > computers which report to popcon.
> 
> I wonder how many of this ~80% is only due to having installed apt-utils
> (99.83%) for apt-extracttemplates (which is responsible for having many
> debconf questions before the installation process starts).
> 
> Anyway, the only util in apt-utils making use of libdb is apt-ftparchive
> which a) isn't used much in Debian – but by some derivatives¹ and b) can
> operate without the backing of a db, but you don't want to run a large
> archive without it.

I agree that the database cache makes a substantial difference at this
scale.  On the occasions when we've suffered corruption and had to
rebuild it, it's taken on the order of 12 hours for a single suite,
while normal runs are more like 15-20 minutes.

> Famous last words, but I doubt there is anything libdb does for
> ftparchive which couldn't be done by any other database, so switching
> shouldn't be too hard database-wise…
> 
> Finding someone performing the daunting task of actually switching code,
> documentation and existing databases over on the other hand… I at least
> don't see me enthusiastically raising my arm crying "let me, let me, …".

I don't blame you!

> ¹ The Census has a field for "Archive tool", but that isn't filled by
> everyone in the census. The biggest fish might be launchpad/Ubuntu.

It's true that Launchpad uses apt-ftparchive for the Ubuntu archive.  We
publish PPAs directly from our database rather than going via
apt-ftparchive, but we've never quite managed to get that to perform
acceptably at the scale of the Ubuntu archive.  I suppose it might be
worth another go.

-- 
Colin Watson                                       [cjwatson@xxxxxxxxxx]