linux-kernel - Re: [PATCH v2 00/14] KEYS: Add support for PGP keys and signatures

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Message-ID: <a9502b8097841c36ca13871b22149eadd3fde355.camel@huaweicloud.com>
Date: Tue, 10 Sep 2024 16:36:21 +0200
From: Roberto Sassu <roberto.sassu@...weicloud.com>
To: Jonathan McDowell <noodles@...th.li>
Cc: dhowells@...hat.com, dwmw2@...radead.org, herbert@...dor.apana.org.au, 
 davem@...emloft.net, linux-kernel@...r.kernel.org,
 keyrings@...r.kernel.org,  linux-crypto@...r.kernel.org,
 zohar@...ux.ibm.com,  linux-integrity@...r.kernel.org, Roberto Sassu
 <roberto.sassu@...wei.com>,  adrian@...e.de, ro@...e.de
Subject: Re: [PATCH v2 00/14] KEYS: Add support for PGP keys and signatures

On Tue, 2024-08-20 at 15:12 +0100, Jonathan McDowell wrote:
> On Mon, Aug 19, 2024 at 05:15:02PM +0200, Roberto Sassu wrote:
> > On Mon, 2024-08-19 at 16:08 +0100, Jonathan McDowell wrote:
> > > On Sun, Aug 18, 2024 at 06:57:42PM +0200, Roberto Sassu wrote:
> > > > From: Roberto Sassu <roberto.sassu@...wei.com>
> > > > 
> > > > Support for PGP keys and signatures was proposed by David long time ago,
> > > > before the decision of using PKCS#7 for kernel modules signatures
> > > > verification was made. After that, there has been not enough interest to
> > > > support PGP too.
> > > 
> > > You might want to update the RFC/bis references to RFC9580, which was
> > > published last month and updates things.
> > 
> > Yes, makes sense (but probably isn't too much hassle to support more
> > things for our purposes?)
> 
> I'm mostly suggesting that the comments/docs point to the latest
> standard rather than the draft version, not changing to support the new
> v6 keys.
> 
> > > Also, I see support for v2 + v3 keys, and this doesn't seem like a good
> > > idea. There are cryptographic issues with fingerprints etc there and I
> > > can't think of a good reason you'd want the kernel to support them. The
> > > same could probably be said of DSA key support too.
> > 
> > Uhm, if I remember correctly I encountered some old PGP keys used to
> > verify RPM packages (need to check). DSA keys are not supported, since
> > the algorithm is not in the kernel.
> 
> I would question the benefit gained from using obsolete key/signature
> types for verification (I was involved in the process of Debian dropping
> them back in *2010* which was later than it should have been). Dropping
> the code for that path means a smaller attack surface/maintenance
> overhead for something that isn't giving a benefit.

Removed support for v3 PGP signatures... but that broke openSUSE
Tumbleweed.

[  295.837602] PGPL: Signature packet with unhandled version 3

Roberto