linux-kernel - Re: [PATCH v8 23/24] ima: Make it independent from 'integrity' LSM

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Date: Wed, 27 Dec 2023 08:22:27 -0500
From: Mimi Zohar <zohar@...ux.ibm.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,
        paul@...l-moore.com, jmorris@...ei.org, serge@...lyn.com,
        dmitry.kasatkin@...il.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-fsdevel@...r.kernel.org, linux-kernel@...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 v8 23/24] ima: Make it independent from 'integrity' LSM

On Thu, 2023-12-14 at 18:08 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@...wei.com>
> 
> Make the 'ima' LSM independent from the 'integrity' LSM by introducing IMA
> own integrity metadata (ima_iint_cache structure, with IMA-specific fields
> from the integrity_iint_cache structure), and by managing it directly from
> the 'ima' LSM.
> 
> Move the remaining IMA-specific flags to security/integrity/ima/ima.h,
> since they are now unnecessary in the common integrity layer.
> 
> Replace integrity_iint_cache with ima_iint_cache in various places
> of the IMA code.
> 
> Then, reserve space in the security blob for the entire ima_iint_cache
> structure, so that it is available for all inodes having the security blob
> allocated (those for which security_inode_alloc() was called).  Adjust the
> IMA code accordingly, call ima_iint_inode() to retrieve the ima_iint_cache
> structure. Keep the non-NULL checks since there can be inodes without
> security blob.

Previously the 'iint' memory was only allocated for regular files in
policy and were tagged S_IMA.  This patch totally changes when and how
memory is being allocated.  Does it make sense to allocate memory at
security_inode_alloc()?  Is this change really necessary for making IMA
a full fledged LSM?

Mimi

> 
> Don't include the inode pointer as field in the ima_iint_cache structure,
> since the association with the inode is clear. Since the inode field is
> missing in ima_iint_cache, pass the extra inode parameter to
> ima_get_verity_digest().
> 
> Finally, register ima_inode_alloc_security/ima_inode_free_security() to
> initialize/deinitialize the new ima_iint_cache structure (before this task
> was done by iint_init_always() and iint_free()). Also, duplicate
> iint_lockdep_annotate() for the ima_iint_cache structure, and name it
> ima_iint_lockdep_annotate().
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>