linux-kernel - Re: [PATCH v9 22/25] evm: Move to LSM infrastructure

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Date: Wed, 07 Feb 2024 22:18:53 -0500
From: Paul Moore <paul@...l-moore.com>
To: Roberto Sassu <roberto.sassu@...weicloud.com>, viro@...iv.linux.org.uk, brauner@...nel.org, chuck.lever@...cle.com, jlayton@...nel.org, neilb@...e.de, kolga@...app.com, Dai.Ngo@...cle.com, tom@...pey.com, jmorris@...ei.org, serge@...lyn.com, zohar@...ux.ibm.com, dmitry.kasatkin@...il.com, eric.snowberg@...cle.com, dhowells@...hat.com, jarkko@...nel.org, stephen.smalley.work@...il.com, eparis@...isplace.org, casey@...aufler-ca.com, shuah@...nel.org, mic@...ikod.net
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org, linux-security-module@...r.kernel.org, linux-integrity@...r.kernel.org, keyrings@...r.kernel.org, selinux@...r.kernel.org, linux-kselftest@...r.kernel.org, Roberto Sassu <roberto.sassu@...wei.com>
Subject: Re: [PATCH v9 22/25] evm: Move to LSM infrastructure

On Jan 15, 2024 Roberto Sassu <roberto.sassu@...weicloud.com> wrote:
> 
> As for IMA, move hardcoded EVM function calls from various places in the
> kernel to the LSM infrastructure, by introducing a new LSM named 'evm'
> (last and always enabled like 'ima'). The order in the Makefile ensures
> that 'evm' hooks are executed after 'ima' ones.

Let's add a comment to the Makefile about this so everyone knows not
to mix up the ordering, otherwise this looks good to me.

At some point I think we may want to introduce the concept of numerical
priorities to security_add_hooks() to add some additional granularity
beyond the LSM_ORDER_XXX priority, but that is something we can do
later.

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

> Make EVM functions as static (except for evm_inode_init_security(), which
> is exported), and register them as hook implementations in init_evm_lsm().
> Also move the inline functions evm_inode_remove_acl(),
> evm_inode_post_remove_acl(), and evm_inode_post_set_acl() from the public
> evm.h header to evm_main.c.
> 
> Unlike before (see commit to move IMA to the LSM infrastructure),
> evm_inode_post_setattr(), evm_inode_post_set_acl(),
> evm_inode_post_remove_acl(), and evm_inode_post_removexattr() are not
> executed for private inodes.
> 
> Finally, add the LSM_ID_EVM case in lsm_list_modules_test.c
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> Reviewed-by: Casey Schaufler <casey@...aufler-ca.com>
> ---
>  fs/attr.c                                     |   2 -
>  fs/posix_acl.c                                |   3 -
>  fs/xattr.c                                    |   2 -
>  include/linux/evm.h                           | 113 -----------------
>  include/uapi/linux/lsm.h                      |   1 +
>  security/integrity/evm/evm_main.c             | 118 +++++++++++++++---
>  security/security.c                           |  43 ++-----
>  .../selftests/lsm/lsm_list_modules_test.c     |   3 +
>  8 files changed, 116 insertions(+), 169 deletions(-)

--
paul-moore.com