On Tue, Sep 10, 2024 at 04:51:22PM +0200, Roberto Sassu wrote: > On Tue, 2024-09-10 at 16:36 +0200, Roberto Sassu wrote: > > 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@xxxxxxxxxx> > > > > > > > > > > > > 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. Is this a signature from a v3 key, or a v3 signature? Unfortunately there are implementations which will issue a v3 signature even from a v4 key; IIRC this ambiguity has been cleared up in the updated RFC. > > [ 295.837602] PGPL: Signature packet with unhandled version 3 > > To add more context, this patch set adds the ability to the kernel to > verify the PGP signature of RPM packages against Linux distributions > PGP keys. > The purpose of this is to verify the authenticity of such RPM packages, > and to extract from them file digests, which are in turn used as > reference values for integrity check (appraisal) with IMA. I don't believe allowing a v3 *key* gives a useful verification that is worth supporting. However unfortunately I think it sounds like support for v3 signatures from v4 keys is necessary. J. -- Listen to the words, they tell you what to do...
