On 10/13/22 15:14, Neal Gompa wrote:
On Thu, Oct 13, 2022 at 4:24 AM Panu Matilainen <pmati...@redhat.com> wrote:
On 10/13/22 10:53, Neal Gompa wrote:
On Thu, Oct 13, 2022 at 3:29 AM Panu Matilainen <pmati...@redhat.com> wrote:
On 10/13/22 07:18, Kevin Kofler via devel wrote:
For the last 20 years or so, RPM has used a home-grown OpenPGP parser
for dealing with keys and signatures. That parser is rather infamous
for its limitations and flaws, and especially in recent years has
proven a significant burden to RPM development. In order to improve
security and free developer resources for dealing with RPM's "core
business" instead, RPM upstream is in the process of deprecating the
internal parser in favor of [https://sequoia-pgp.org/ Sequoia PGP]
based solution written in Rust.
Why are you using a new library written in Rust? Can you not use one of the
existing mature C implementations of OpenPGP? gpgme maybe?
Had there been such an option, we would've switched over years ago.
Gpgme is based around calling and communicating with an external gpg
process, which is a setup you do NOT want in the rpm context where
chroots come and go etc. Also, rpm requires access to the "low-level"
digests-in-progress because it calculates multiple things on a single read.
The real problem is that all other OpenPGP implementations died out
because of GnuPG. And then GnuPG made the choice to force an
inter-process model.
At work, I deal with this on Debian systems, which do indeed use GnuPG
for this. It creates a lot of problems, especially for building images
and dealing with chroots, which is why in the context of RPM PGP
upstream, I never pushed to consider it.
The most serious problems with PackageKit memory leaks and hangs are
actually caused by GnuPG, since DNF uses it for some GPG stuff because
there's no API for using RPM's PGP capabilities. There's no fix unless
the RPM and DNF teams agree on an API and build it out so that libdnf
and librepo no longer need to use GnuPG through gpgme anymore.
This is also the underlying reason why Red Hat has resisted
implementing signed repository metadata and enforcing it by default.
Of course this is a bit of a catch-22 as well, as there's no
motivation to find a solution because neither Fedora nor RHEL offer
signed repository metadata despite repeated calls for it over the past
decade.
Now, don't get me wrong: I'm personally extremely unhappy about having
to depend on the Sequoia stack for RPM PGP. I have a strong distaste
for the Rust community ecosystem these days, and I don't love the idea
of having to have LLVM in the core bootstrap chain (hopefully gcc-rs
will be in place soon enough!). But we literally don't have any other
options. GnuPG/GPGME is out of the question for the reasons Panu and I
stated, and NeoPG died several years ago. There are no C/C++ libraries
for OpenPGP verification.
There's RNP (in C++, used by Thunderbird at least), but alas that
doesn't expose the digest-in-progress either. So at least in it's
current form, it's not an option for rpm. Also, the API appears to have
all manner of quirks and gotchas that aren't welcome in a
security-critical piece.
Huh, I'd forgotten about RNP. It seems it now has an OpenSSL backend
and at least the verification API (which is what RPM would use) seems
to be getting love lately. Insofar as quirks and gotchas, I'm not a
great judge of that at the moment, but I don't think it could be worse
than what we have with GnuPG.
The missing "digest-in-progress" thing is an issue, I guess. Have we
raised the issue with them about it?
No, because beneath the surface it didn't seem all that appetizing
afterall. See
https://sequoia-pgp.org/blog/2021/05/06/202105-thunderbird-rnp-and-the-importance-of-a-good-api/
for an example (even bearing in mind that a blog post from a competitor
may be necessarily a little opionated), but its reputation/security
record doesn't seem that great.
It's something to keep an eye on of course, it would be good to have
alternatives available.
As for bootstrap, there will always (have to) be a way to build rpm
without depending on Rust. Even if that meant no signature verification
support in such a configuration.
Eck. What about the x509 based stuff we were talking about last year?
All the crypto backends RPM supports now support that stuff out of the
box.
Embedded x509 signatures (certs) to replace GPG signatures could work
as an alternative.
x509 seems to be loathed even more than PGP, so it doesn't seem that
appetizing either.
If someone with known crypto-clue would send patches they would be
looked at, *I* have no prejudice about x509 because I also have no clue
about it. Ditto for Signify, which often gets brought up in these
discussions.
And yet, that all is largely irrelevant for the subject at hand: no
matter what, rpm will need OpenPGP support for years to come because
existing content will need to remain usable for a long, long time.
- Panu -
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