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From:   Fan Wu <wufan@linux.microsoft.com>
To:     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
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: [RFC PATCH v11 11/19] dm verity: set DM_TARGET_SINGLETON feature flag
Date:   Wed,  4 Oct 2023 15:09:38 -0700
Message-Id: <1696457386-3010-12-git-send-email-wufan@linux.microsoft.com>
In-Reply-To: <1696457386-3010-1-git-send-email-wufan@linux.microsoft.com>
References: <1696457386-3010-1-git-send-email-wufan@linux.microsoft.com>
Precedence: bulk

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(-)

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