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From: Paul Moore <paul@paul-moore.com>
Date: Mon, 12 Feb 2024 12:56:50 -0500
Message-ID: <CAHC9VhTY=X7z5SRQZzFe25FGB2E3FBBkuZ_YYA1+ETyr7pv=tA@mail.gmail.com>
Subject: Re: [PATCH v9 19/25] integrity: Move integrity_kernel_module_request()
 to IMA
To: Stefan Berger <stefanb@linux.ibm.com>
Cc: Roberto Sassu <roberto.sassu@huaweicloud.com>, viro@zeniv.linux.org.uk, 
	brauner@kernel.org, chuck.lever@oracle.com, jlayton@kernel.org, neilb@suse.de, 
	kolga@netapp.com, Dai.Ngo@oracle.com, tom@talpey.com, jmorris@namei.org, 
	serge@hallyn.com, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, 
	eric.snowberg@oracle.com, dhowells@redhat.com, jarkko@kernel.org, 
	stephen.smalley.work@gmail.com, eparis@parisplace.org, casey@schaufler-ca.com, 
	shuah@kernel.org, mic@digikod.net, linux-kernel@vger.kernel.org, 
	linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, 
	linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, 
	keyrings@vger.kernel.org, selinux@vger.kernel.org, 
	linux-kselftest@vger.kernel.org, Roberto Sassu <roberto.sassu@huawei.com>
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On Mon, Feb 12, 2024 at 12:48=E2=80=AFPM Stefan Berger <stefanb@linux.ibm.c=
om> wrote:
> On 1/15/24 13:18, Roberto Sassu wrote:

..

> > +/**
> > + * ima_kernel_module_request - Prevent crypto-pkcs1pad(rsa,*) requests
> > + * @kmod_name: kernel module name
> > + *
> > + * We have situation, when public_key_verify_signature() in case of RS=
A > + * algorithm use alg_name to store internal information in order to
> > + * construct an algorithm on the fly, but crypto_larval_lookup() will =
try
> > + * to use alg_name in order to load kernel module with same name.
> > + * Since we don't have any real "crypto-pkcs1pad(rsa,*)" kernel module=
s,
> > + * we are safe to fail such module request from crypto_larval_lookup()=
.
> > + *
> > + * In this way we prevent modprobe execution during digsig verificatio=
n
> > + * and avoid possible deadlock if modprobe and/or it's dependencies
> > + * also signed with digsig.
>
> This text needs to some reformulation at some point..

There is no time like the present.  If you have a suggestion I would
love to hear it and I'm sure Roberto would too.

--=20
paul-moore.com