From: Roberto Sassu <roberto.sassu@huaweicloud.com>
To: Jonathan McDowell <noodles@earth.li>
Cc: dhowells@redhat.com, dwmw2@infradead.org,
herbert@gondor.apana.org.au, davem@davemloft.net,
linux-kernel@vger.kernel.org, keyrings@vger.kernel.org,
linux-crypto@vger.kernel.org, zohar@linux.ibm.com,
linux-integrity@vger.kernel.org,
Roberto Sassu <roberto.sassu@huawei.com>,
adrian@suse.de, ro@suse.de
Subject: Re: [PATCH v2 00/14] KEYS: Add support for PGP keys and signatures
Date: Wed, 11 Sep 2024 11:55:23 +0200 [thread overview]
Message-ID: <34c4c5b31e795144a6fdd258c99ce3da89c97c03.camel@huaweicloud.com> (raw)
In-Reply-To: <ZuBi56VwWxxX2Ce5@earth.li>
On Tue, 2024-09-10 at 16:16 +0100, Jonathan McDowell wrote:
> 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@huawei.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.
>
> 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.
Yes, it looks a v3 signature from a v4 key.
> > > [ 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.
Yes, after re-adding support for v3 signatures, openSUSE Tumbleweed is
back to normal, does IMA appraisal with RPM packages.
Thanks
Roberto
next prev parent reply other threads:[~2024-09-11 9:55 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-18 16:57 [PATCH v2 00/14] KEYS: Add support for PGP keys and signatures Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 01/14] mpi: Introduce mpi_key_length() Roberto Sassu
2024-08-19 17:55 ` Jarkko Sakkinen
2024-08-18 16:57 ` [PATCH v2 02/14] rsa: add parser of raw format Roberto Sassu
2024-08-19 17:56 ` Jarkko Sakkinen
2024-08-18 16:57 ` [PATCH v2 03/14] PGPLIB: PGP definitions (RFC 4880) Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 04/14] PGPLIB: Basic packet parser Roberto Sassu
2024-08-19 14:34 ` Jeff Johnson
2024-08-19 15:06 ` Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 05/14] PGPLIB: Signature parser Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 06/14] KEYS: PGP data parser Roberto Sassu
2024-08-19 14:36 ` Jeff Johnson
2024-08-19 14:38 ` Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 07/14] KEYS: Provide PGP key description autogeneration Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 08/14] KEYS: PGP-based public key signature verification Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 09/14] KEYS: Retry asym key search with partial ID in restrict_link_by_signature() Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 10/14] KEYS: Calculate key digest and get signature of the key Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 11/14] verification: introduce verify_pgp_signature() Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 12/14] PGP: Provide a key type for testing PGP signatures Roberto Sassu
2024-08-19 14:37 ` Jeff Johnson
2024-08-18 16:57 ` [PATCH v2 13/14] KEYS: Provide a function to load keys from a PGP keyring blob Roberto Sassu
2024-08-18 16:57 ` [PATCH v2 14/14] KEYS: Introduce load_pgp_public_keyring() Roberto Sassu
2024-08-19 15:08 ` [PATCH v2 00/14] KEYS: Add support for PGP keys and signatures Jonathan McDowell
2024-08-19 15:15 ` Roberto Sassu
2024-08-20 14:12 ` Jonathan McDowell
2024-08-20 14:14 ` Roberto Sassu
2024-09-10 14:36 ` Roberto Sassu
2024-09-10 14:51 ` Roberto Sassu
2024-09-10 15:16 ` Jonathan McDowell
2024-09-11 9:55 ` Roberto Sassu [this message]
2024-08-19 16:30 ` Roberto Sassu
2024-08-19 17:53 ` Jarkko Sakkinen
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