* [PATCH 1/2] configfs: move CONFIGFS_MAGIC definition to magic.h
2026-08-18 19:35 [PATCH 0/2] ima: don't measure/appraise files on configfs Frederick Lawler
@ 2026-08-18 19:35 ` Frederick Lawler
2026-08-19 9:21 ` Breno Leitao
2026-08-18 19:35 ` [PATCH 2/2] ima: don't measure/appraise files on configfs Frederick Lawler
1 sibling, 1 reply; 5+ messages in thread
From: Frederick Lawler @ 2026-08-18 19:35 UTC (permalink / raw)
To: Andreas Hindborg, Breno Leitao, Mimi Zohar, Roberto Sassu,
Dmitry Kasatkin, Eric Snowberg, Paul Moore, James Morris,
Serge E. Hallyn
Cc: linux-kernel, linux-integrity, linux-security-module, kernel-team,
Frederick Lawler
IMA shouldn't measure or appraise configfs, but currently does because
it's missing from the default exclusion policies. Move CONFIGFS_MAGIC to
magic.h to expose the file system's magic to IMA, as well as other userland
applications.
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Frederick Lawler <fred@cloudflare.com>
---
fs/configfs/mount.c | 4 +---
include/uapi/linux/magic.h | 1 +
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index 4929f343118946eaa55a539db4192e9c6621a8dc..d8cac1cbf3bd573a0549f2f044714c9d669205a4 100644
--- a/fs/configfs/mount.c
+++ b/fs/configfs/mount.c
@@ -9,6 +9,7 @@
*/
#include <linux/fs.h>
+#include <linux/magic.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/fs_context.h>
@@ -19,9 +20,6 @@
#include <linux/configfs.h>
#include "configfs_internal.h"
-/* Random magic number */
-#define CONFIGFS_MAGIC 0x62656570
-
static struct vfsmount *configfs_mount = NULL;
struct kmem_cache *configfs_dir_cachep;
static int configfs_mnt_count = 0;
diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
index 4f2da935a76ccae6e1c3310b2fae5379186548b8..d5b9958ddfaae90b270b66fe7853c5a3d49ce739 100644
--- a/include/uapi/linux/magic.h
+++ b/include/uapi/linux/magic.h
@@ -8,6 +8,7 @@
#define AUTOFS_SUPER_MAGIC 0x0187
#define CEPH_SUPER_MAGIC 0x00c36400
#define CODA_SUPER_MAGIC 0x73757245
+#define CONFIGFS_MAGIC 0x62656570 /* some random number */
#define CRAMFS_MAGIC 0x28cd3d45 /* some random number */
#define CRAMFS_MAGIC_WEND 0x453dcd28 /* magic number with the wrong endianess */
#define DEBUGFS_MAGIC 0x64626720
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 2/2] ima: don't measure/appraise files on configfs
2026-08-18 19:35 [PATCH 0/2] ima: don't measure/appraise files on configfs Frederick Lawler
2026-08-18 19:35 ` [PATCH 1/2] configfs: move CONFIGFS_MAGIC definition to magic.h Frederick Lawler
@ 2026-08-18 19:35 ` Frederick Lawler
1 sibling, 0 replies; 5+ messages in thread
From: Frederick Lawler @ 2026-08-18 19:35 UTC (permalink / raw)
To: Andreas Hindborg, Breno Leitao, Mimi Zohar, Roberto Sassu,
Dmitry Kasatkin, Eric Snowberg, Paul Moore, James Morris,
Serge E. Hallyn
Cc: linux-kernel, linux-integrity, linux-security-module, kernel-team,
Frederick Lawler, syzbot+448c2e24b1ceff13ed2a
When IMA appraises/measures a file configfs, it has an opportunity to
hold onto the ima_iint_mutex while another file from a different file
system is attempting to appraise/measure. This may cause a cyclical
lock dependency.
Add configfs to the default don't measure/appraise lists, similarly to
other pseudo file systems.
Reported-by: syzbot+448c2e24b1ceff13ed2a@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/6a77c7cd.b50370da.49fe0.0031.GAE@google.com/
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Frederick Lawler <fred@cloudflare.com>
---
security/integrity/ima/ima_policy.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index f79d07bb63c6fc4ba6fe594140de8d59f57e4f0b..68d9a5e6c232ea0678e9f51f105cebecccccb43e 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -165,7 +165,10 @@ static struct ima_rule_entry dont_measure_rules[] __ro_after_init = {
{.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC,
.flags = IMA_FSMAGIC},
{.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
- {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}
+ {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC,
+ .flags = IMA_FSMAGIC},
+ {.action = DONT_MEASURE, .fsmagic = CONFIGFS_MAGIC,
+ .flags = IMA_FSMAGIC}
};
static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
@@ -211,6 +214,8 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
{.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC},
{.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
{.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC},
+ {.action = DONT_APPRAISE, .fsmagic = CONFIGFS_MAGIC,
+ .flags = IMA_FSMAGIC},
#ifdef CONFIG_IMA_WRITE_POLICY
{.action = APPRAISE, .func = POLICY_CHECK,
.flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
--
2.43.0
^ permalink raw reply related [flat|nested] 5+ messages in thread