From: Fan Wu <wufan@linux.microsoft.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: corbet@lwn.net, zohar@linux.ibm.com, jmorris@namei.org,
serge@hallyn.com, tytso@mit.edu, ebiggers@kernel.org,
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, fsverity@lists.linux.dev,
linux-block@vger.kernel.org, dm-devel@lists.linux.dev,
audit@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v18 12/21] dm: add finalize hook to target_type
Date: Wed, 8 May 2024 15:30:14 -0700 [thread overview]
Message-ID: <212b02a8-f5f0-4433-a726-1639dda61790@linux.microsoft.com> (raw)
In-Reply-To: <aa767961-5e3-2ceb-1a1e-ff66a8eed649@redhat.com>
On 5/8/2024 10:17 AM, Mikulas Patocka wrote:
>
>
> On Fri, 3 May 2024, Fan Wu wrote:
>
>> This patch adds a target finalize hook.
>>
>> The hook is triggered just before activating an inactive table of a
>> mapped device. If it returns an error the __bind get cancelled.
>>
>> The dm-verity target will use this hook to attach the dm-verity's
>> roothash metadata to the block_device struct of the mapped device.
>>
>> Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
>
> Hi
>
> Why not use the preresume callback?
>
> Is there some reason why do we need a new callback instead of using the
> existing one?
>
> Mikulas
Thanks for the suggestion.
Mike suggested the new finalize() callback. I think the reason for not
using the preresume() callback is that there are multiple points that
can fail before activating an inactive table of a mapped device which
can potentially lead to inconsistent state.
In our specific case, we are trying to associate dm-verity's roothash
metadata with the block_device struct of the mapped device inside the
callback.
If we use the preresume() callback for the work and an error occurs
between the callback and the table activation, this leave the
block_device struct in an inconsistent state.
This is because now the block device contains the roothash metadata of
it's inactive table due to the preresume() callback, but the activation
failed so the mapped device is still using the old table.
The new finalize() callback guarantees that the callback happens just
before the table activation, thus avoiding the inconsistency.
-Fan
next prev parent reply other threads:[~2024-05-08 22:30 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-03 22:32 [PATCH v18 00/21] Integrity Policy Enforcement LSM (IPE) Fan Wu
2024-05-03 22:32 ` [PATCH v18 01/21] security: add ipe lsm Fan Wu
2024-05-03 22:32 ` [PATCH v18 02/21] ipe: add policy parser Fan Wu
2024-05-03 22:32 ` [PATCH v18 03/21] ipe: add evaluation loop Fan Wu
2024-05-03 22:32 ` [PATCH v18 04/21] ipe: add LSM hooks on execution and kernel read Fan Wu
2024-05-03 22:32 ` [PATCH v18 05/21] initramfs|security: Add a security hook to do_populate_rootfs() Fan Wu
2024-05-03 22:32 ` [PATCH v18 06/21] ipe: introduce 'boot_verified' as a trust provider Fan Wu
2024-05-03 22:32 ` [PATCH v18 07/21] security: add new securityfs delete function Fan Wu
2024-05-03 22:32 ` [PATCH v18 08/21] ipe: add userspace interface Fan Wu
2024-05-03 22:32 ` [PATCH v18 09/21] uapi|audit|ipe: add ipe auditing support Fan Wu
2024-05-03 22:32 ` [PATCH v18 10/21] ipe: add permissive toggle Fan Wu
2024-05-03 22:32 ` [PATCH v18 11/21] block,lsm: add LSM blob and new LSM hooks for block device Fan Wu
2024-05-03 22:32 ` [PATCH v18 12/21] dm: add finalize hook to target_type Fan Wu
2024-05-08 17:17 ` Mikulas Patocka
2024-05-08 22:30 ` Fan Wu [this message]
2024-05-09 17:07 ` Mikulas Patocka
2024-05-17 19:13 ` Fan Wu
2024-05-20 12:31 ` Mikulas Patocka
2024-05-21 21:42 ` Fan Wu
2024-05-03 22:32 ` [PATCH v18 13/21] dm verity: expose root hash digest and signature data to LSMs Fan Wu
2024-05-03 22:32 ` [PATCH v18 14/21] ipe: add support for dm-verity as a trust provider Fan Wu
2024-05-03 22:32 ` [PATCH v18 15/21] security: add security_inode_setintegrity() hook Fan Wu
2024-05-03 22:32 ` [PATCH v18 16/21] fsverity: expose verified fsverity built-in signatures to LSMs Fan Wu
2024-05-14 19:55 ` Paul Moore
2024-05-03 22:32 ` [PATCH v18 17/21] ipe: enable support for fs-verity as a trust provider Fan Wu
2024-05-03 22:32 ` [PATCH v18 18/21] scripts: add boot policy generation program Fan Wu
2024-05-03 22:32 ` [PATCH v18 19/21] ipe: kunit test for parser Fan Wu
2024-05-03 22:32 ` [PATCH v18 20/21] Documentation: add ipe documentation Fan Wu
2024-05-04 8:04 ` Bagas Sanjaya
2024-05-04 20:13 ` Fan Wu
2024-05-05 0:15 ` Bagas Sanjaya
2024-05-14 19:50 ` Paul Moore
2024-05-03 22:32 ` [PATCH v18 21/21] MAINTAINERS: ipe: add ipe maintainer information Fan Wu
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