linux-kernel - [PATCH] dm-verity: fix dm_is_verity_target() when dm-verity is builtin

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Message-ID: <20240703200813.64802-1-ebiggers@kernel.org>
Date: Wed,  3 Jul 2024 13:08:13 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: dm-devel@...ts.linux.dev,
	Alasdair Kergon <agk@...hat.com>,
	Mike Snitzer <snitzer@...nel.org>,
	Mikulas Patocka <mpatocka@...hat.com>
Cc: linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org,
	Matthias Kaehlcke <mka@...omium.org>,
	Kees Cook <keescook@...omium.org>
Subject: [PATCH] dm-verity: fix dm_is_verity_target() when dm-verity is builtin

From: Eric Biggers <ebiggers@...gle.com>

When CONFIG_DM_VERITY=y, dm_is_verity_target() returned true for any
builtin dm target, not just dm-verity.  Fix this by checking for
verity_target instead of THIS_MODULE (which is NULL for builtin code).

Fixes: b6c1c5745ccc ("dm: Add verity helpers for LoadPin")
Cc: stable@...r.kernel.org
Cc: Matthias Kaehlcke <mka@...omium.org>
Cc: Kees Cook <keescook@...omium.org>
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 drivers/md/dm-verity-target.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index 0a2399d958b7..cf659c8feb29 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -1519,18 +1519,10 @@ static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	verity_dtr(ti);
 
 	return r;
 }
 
-/*
- * Check whether a DM target is a verity target.
- */
-bool dm_is_verity_target(struct dm_target *ti)
-{
-	return ti->type->module == THIS_MODULE;
-}
-
 /*
  * Get the verity mode (error behavior) of a verity target.
  *
  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
  * target.
@@ -1580,10 +1572,18 @@ static struct target_type verity_target = {
 	.iterate_devices = verity_iterate_devices,
 	.io_hints	= verity_io_hints,
 };
 module_dm(verity);
 
+/*
+ * Check whether a DM target is a verity target.
+ */
+bool dm_is_verity_target(struct dm_target *ti)
+{
+	return ti->type == &verity_target;
+}
+
 MODULE_AUTHOR("Mikulas Patocka <mpatocka@...hat.com>");
 MODULE_AUTHOR("Mandeep Baines <msb@...omium.org>");
 MODULE_AUTHOR("Will Drewry <wad@...omium.org>");
 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
 MODULE_LICENSE("GPL");

base-commit: ed28fe59c042e9b5bf3b15050aa6ee67834dc852
-- 
2.45.2