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Date: Wed, 07 Feb 2024 22:18:50 -0500
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From: Paul Moore <paul@paul-moore.com>
To: 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
Cc: 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>
Subject: Re: [PATCH v9 19/25] integrity: Move integrity_kernel_module_request()  to IMA
References: <20240115181809.885385-20-roberto.sassu@huaweicloud.com>
In-Reply-To: <20240115181809.885385-20-roberto.sassu@huaweicloud.com>

On Jan 15, 2024 Roberto Sassu <roberto.sassu@huaweicloud.com> wrote:
> 
> In preparation for removing the 'integrity' LSM, move
> integrity_kernel_module_request() to IMA, and rename it to
> ima_kernel_module_request().
> 
> Compile it conditionally if CONFIG_INTEGRITY_ASYMMETRIC_KEYS is enabled,
> and call it from security.c (removed afterwards with the move of IMA to the
> LSM infrastructure).
> 
> Adding this hook cannot be avoided, since IMA has no control on the flags
> passed to crypto_alloc_sig() in public_key_verify_signature(), and thus
> cannot pass CRYPTO_NOLOAD, which solved the problem for EVM hashing with
> commit e2861fa71641 ("evm: Don't deadlock if a crypto algorithm is
> unavailable").
> 
> EVM alone does not need to implement this hook, first because there is no
> mutex to deadlock, and second because even if it had it, there should be a
> recursive call. However, since verification from EVM can be initiated only
> by setting inode metadata, deadlock would occur if modprobe would do the
> same while loading a kernel module (which is unlikely).
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
>  include/linux/ima.h                    | 10 +++++++++
>  include/linux/integrity.h              | 13 ------------
>  security/integrity/digsig_asymmetric.c | 23 --------------------
>  security/integrity/ima/ima_main.c      | 29 ++++++++++++++++++++++++++
>  security/security.c                    |  2 +-
>  5 files changed, 40 insertions(+), 37 deletions(-)

Acked-by: Paul Moore <paul@paul-moore.com>

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