Received-SPF: pass (google.com: domain of linux-kernel+bounces-68990-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Message-ID: <5916fa3ac3d0ce2ade71e7ed1c9eb6923e374c1f.camel@huaweicloud.com>
Subject: Re: [RFC 6/8] KEYS: PGP data parser
From: Roberto Sassu <roberto.sassu@huaweicloud.com>
To: Matthew Wilcox <willy@infradead.org>, Petr Tesarik
	 <petrtesarik@huaweicloud.com>
Cc: Dave Hansen <dave.hansen@intel.com>, Petr =?UTF-8?Q?Tesa=C5=99=C3=ADk?=
 <petr@tesarici.cz>, Jonathan Corbet <corbet@lwn.net>, Thomas Gleixner
 <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov
 <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, "maintainer:X86
 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>, "H. Peter Anvin"
 <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, Oleg Nesterov
 <oleg@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Xin Li
 <xin3.li@intel.com>, Arnd Bergmann <arnd@arndb.de>,  Andrew Morton
 <akpm@linux-foundation.org>, Rick Edgecombe <rick.p.edgecombe@intel.com>,
 Kees Cook <keescook@chromium.org>, "Masami Hiramatsu (Google)"
 <mhiramat@kernel.org>,  Pengfei Xu <pengfei.xu@intel.com>, Josh Poimboeuf
 <jpoimboe@kernel.org>, Ze Gao <zegao2021@gmail.com>,  "Kirill A. Shutemov"
 <kirill.shutemov@linux.intel.com>, Kai Huang <kai.huang@intel.com>, David
 Woodhouse <dwmw@amazon.co.uk>,  Brian Gerst <brgerst@gmail.com>, Jason
 Gunthorpe <jgg@ziepe.ca>, Joerg Roedel <jroedel@suse.de>, "Mike Rapoport
 (IBM)" <rppt@kernel.org>, Tina Zhang <tina.zhang@intel.com>, Jacob Pan
 <jacob.jun.pan@linux.intel.com>, "open list:DOCUMENTATION"
 <linux-doc@vger.kernel.org>, open list <linux-kernel@vger.kernel.org>,
 David Howells <dhowells@redhat.com>, Petr Tesarik
 <petr.tesarik1@huawei-partners.com>
Date: Fri, 16 Feb 2024 17:53:01 +0100
In-Reply-To: <Zc-Q5pVHjngq9lpX@casper.infradead.org>
References: <fb4a40c7-af9a-406a-95ab-406595f3ffe5@intel.com>
	 <20240216152435.1575-1-petrtesarik@huaweicloud.com>
	 <20240216152435.1575-7-petrtesarik@huaweicloud.com>
	 <Zc-Q5pVHjngq9lpX@casper.infradead.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.44.4-0ubuntu2 
Precedence: bulk
MIME-Version: 1.0

On Fri, 2024-02-16 at 16:44 +0000, Matthew Wilcox wrote:
> On Fri, Feb 16, 2024 at 04:24:33PM +0100, Petr Tesarik wrote:
> > From: David Howells <dhowells@redhat.com>
> >=20
> > Implement a PGP data parser for the crypto key type to use when
> > instantiating a key.
> >=20
> > This parser attempts to parse the instantiation data as a PGP packet
> > sequence (RFC 4880) and if it parses okay, attempts to extract a public=
-key
> > algorithm key or subkey from it.
>=20
> I don't understand why we want to do this in-kernel instead of in
> userspace and then pass in the actual key.

Sigh, this is a long discussion.

PGP keys would be used as a system-wide trust anchor to verify RPM
package headers, which already contain file digests that can be used as
reference values for kernel-enforced integrity appraisal.

With the assumptions that:

- In a locked-down system the kernel has more privileges than root
- The kernel cannot offload this task to an user space process due to
  insufficient isolation

the only available option is to do it in the kernel (that is what I got
as suggestion).

Roberto