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Date:   Mon, 23 Oct 2023 23:52:29 -0400
Message-ID: <85311850a862fe6ccb946634429b890a.paul@paul-moore.com>
From:   Paul Moore <paul@paul-moore.com>
To:     Fan Wu <wufan@linux.microsoft.com>, 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
Cc:     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@redhat.com, audit@vger.kernel.org,
        roberto.sassu@huawei.com, linux-kernel@vger.kernel.org,
        Fan Wu <wufan@linux.microsoft.com>
Subject: Re: [PATCH RFC v11 11/19] dm verity: set DM_TARGET_SINGLETON feature  flag
References: <1696457386-3010-12-git-send-email-wufan@linux.microsoft.com>
In-Reply-To: <1696457386-3010-12-git-send-email-wufan@linux.microsoft.com>
Precedence: bulk

On Oct  4, 2023 Fan Wu <wufan@linux.microsoft.com> wrote:
> 
> The device-mapper has a flag to mark targets as singleton, which is a
> required flag for immutable targets. Without this flag, multiple
> dm-verity targets can be added to a mapped device, which has no
> practical use cases and will let dm_table_get_immutable_target return
> NULL. This patch adds the missing flag, restricting only one
> dm-verity target per mapped device.
> 
> Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
> ---
> v1-v10:
>   + Not present
> ---
>  drivers/md/dm-verity-target.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

This seems reasonable to me and matches with other users of
DM_TARGET_IMMUTABLE.

Alasdair, Mike, can we get an ACK on this?

> diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
> index 26adcfea0302..80673b66c194 100644
> --- a/drivers/md/dm-verity-target.c
> +++ b/drivers/md/dm-verity-target.c
> @@ -1503,7 +1503,7 @@ int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned i
>  
>  static struct target_type verity_target = {
>  	.name		= "verity",
> -	.features	= DM_TARGET_IMMUTABLE,
> +	.features	= DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
>  	.version	= {1, 9, 0},
>  	.module		= THIS_MODULE,
>  	.ctr		= verity_ctr,
> -- 
> 2.25.1

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