From: Fan Wu <wufan@linux.microsoft.com>
To: Casey Schaufler <casey@schaufler-ca.com>,
Eric Biggers <ebiggers@kernel.org>
Cc: corbet@lwn.net, zohar@linux.ibm.com, jmorris@namei.org,
serge@hallyn.com, tytso@mit.edu, axboe@kernel.dk, agk@redhat.com,
snitzer@kernel.org, eparis@redhat.com, paul@paul-moore.com,
linux-doc@vger.kernel.org, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fscrypt@vger.kernel.org, linux-block@vger.kernel.org,
dm-devel@lists.linux.dev, audit@vger.kernel.org,
linux-kernel@vger.kernel.org,
Deven Bowers <deven.desai@linux.microsoft.com>
Subject: Re: [RFC PATCH v14 15/19] fsverity: consume builtin signature via LSM hook
Date: Tue, 12 Mar 2024 12:08:49 -0700 [thread overview]
Message-ID: <746a5548-0e98-4953-9e71-16b881c63aa8@linux.microsoft.com> (raw)
In-Reply-To: <568fae5e-a6d4-4832-a1a1-ac3f4f93d650@schaufler-ca.com>
On 3/12/2024 11:51 AM, Casey Schaufler wrote:
> On 3/12/2024 11:14 AM, Fan Wu wrote:
>>
>>
>> On 3/11/2024 8:07 PM, Eric Biggers wrote:
>>> On Mon, Mar 11, 2024 at 07:57:12PM -0700, Eric Biggers wrote:
>>>>
>>>> As I've said before, this commit message needs some work. It
>>>> currently doesn't
>>>> say anything about what the patch actually does.
>>>>
>>>> BTW, please make sure you're Cc'ing the fsverity mailing list
>>>> (fsverity@lists.linux.dev), not fscrypt
>>>> (linux-fscrypt@vger.kernel.org).
>>>
>>> Also, I thought this patch was using a new LSM hook, but I now see
>>> that you're
>>> actually abusing the existing security_inode_setsecurity() LSM hook.
>>> Currently
>>> that hook is called when an xattr is set. I don't see any precedent for
>>> overloading it for other purposes. This seems problematic, as it
>>> means that a
>>> request to set an xattr with the name you chose
>>> ("fsverity.builtin-sig") will be
>>> interpreted by LSMs as the fsverity builtin signature. A dedicated
>>> LSM hook may
>>> be necessary to avoid issues with overloading the existing xattr hook
>>> like this.
>>>
>>> - Eric
>>
>> Thanks for the suggestion. I found that using
>> security_inode_setsecurity() causes issues with SMACK's
>> inode_setsecurity() hook. I will crate a dedicated new hook like
>> security_inode_setsig() in the next version.
>
> What is the issue you encountered with the Smack hook?
>
The current hook call for saving file signature will fail at
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/security/smack/smack_lsm.c#n2855
.
The issue is file signature size is larger than SMK_LONGLABEL so if
SMACK is enabled the SMACK's hook will return -EINVAL, which prevents us
to use security_inode_setsecurity() to save file signature into security
blob.
We could also make security_inode_setsecurity() more generic instead of
for xattr only, any suggestions?
-Fan
next prev parent reply other threads:[~2024-03-12 19:08 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-06 23:34 [RFC PATCH v14 00/19] Integrity Policy Enforcement LSM (IPE) Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 01/19] security: add ipe lsm Fan Wu
2024-03-11 14:25 ` Roberto Sassu
2024-03-11 18:10 ` Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 02/19] ipe: add policy parser Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 03/19] ipe: add evaluation loop Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 04/19] ipe: add LSM hooks on execution and kernel read Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 05/19] initramfs|security: Add a security hook to do_populate_rootfs() Fan Wu
2024-03-11 14:53 ` Roberto Sassu
2024-03-11 18:34 ` Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 06/19] ipe: introduce 'boot_verified' as a trust provider Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 07/19] security: add new securityfs delete function Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 08/19] ipe: add userspace interface Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 09/19] uapi|audit|ipe: add ipe auditing support Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 10/19] ipe: add permissive toggle Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 11/19] block|security: add LSM blob to block_device Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 12/19] dm: add finalize hook to target_type Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 13/19] dm verity: consume root hash digest and signature data via LSM hook Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 14/19] ipe: add support for dm-verity as a trust provider Fan Wu
2024-03-07 0:01 ` Randy Dunlap
2024-03-06 23:34 ` [RFC PATCH v14 15/19] fsverity: consume builtin signature via LSM hook Fan Wu
2024-03-12 2:57 ` Eric Biggers
2024-03-12 3:07 ` Eric Biggers
2024-03-12 13:12 ` Paul Moore
2024-03-12 18:14 ` Fan Wu
2024-03-12 18:51 ` Casey Schaufler
2024-03-12 19:08 ` Fan Wu [this message]
2024-03-12 20:07 ` Paul Moore
2024-03-12 18:33 ` Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 16/19] ipe: enable support for fs-verity as a trust provider Fan Wu
2024-03-07 0:02 ` Randy Dunlap
2024-03-06 23:34 ` [RFC PATCH v14 17/19] scripts: add boot policy generation program Fan Wu
2024-03-07 0:05 ` Randy Dunlap
2024-03-06 23:34 ` [RFC PATCH v14 18/19] ipe: kunit test for parser Fan Wu
2024-03-06 23:34 ` [RFC PATCH v14 19/19] documentation: add ipe documentation Fan Wu
2024-03-09 1:14 ` [RFC PATCH v14 00/19] Integrity Policy Enforcement LSM (IPE) Paul Moore
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