[PATCH v1 1/2] LSM: add a release() hook for the clean exit cleanup of the LSM modules

[PATCH v1 1/2] LSM: add a release() hook for the clean exit cleanup of the LSM modules

[Mirsad Goran Todorovac]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 2193 bytes --]

The LSM modules, namely integrity, do not have a clean way to deallocate
resources allocated in the init() hook or later in their lifetime. The
resources are destroyed on kernel shutdown in an undefined order.

This will allow a .release member per LSM module and calling proper
destructors in a well-behaved order.

Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Mickaël Salaün <mic@digikod.net>
Cc: Frederick Lawler <fred@cloudflare.com>

---
 include/linux/lsm_hooks.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 6e156d2acffc..d5a6ab9b5eb2 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1724,6 +1724,7 @@ struct lsm_info {
 	unsigned long flags;	/* Optional: flags describing LSM */
 	int *enabled;		/* Optional: controlled by CONFIG_LSM */
 	int (*init)(void);	/* Required. */
+	int (*release)(void);	/* Release associated resources */
 	struct lsm_blob_sizes *blobs; /* Optional: for blob sharing. */
 };
 

--
Mirsad Goran Todorovac
Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu
 
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb, Republic of Croatia
The European Union

---
 include/linux/lsm_hooks.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 0a5ba81f7367..db3e57e7738b 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1724,6 +1724,7 @@ struct lsm_info {
 	unsigned long flags;	/* Optional: flags describing LSM */
 	int *enabled;		/* Optional: controlled by CONFIG_LSM */
 	int (*init)(void);	/* Required. */
+	int (*release)(void);	/* Release associated resources */
 	struct lsm_blob_sizes *blobs; /* Optional: for blob sharing. */
 };
 
-- 
2.30.2

[PATCH v1 2/2] integrity: Add the release() hook to the integrity LSM module

[Mirsad Goran Todorovac]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 1425 bytes --]

The kmem_cache_create() callback in the init() hook of the integrity LSM
module doesn't have a corresponding kmem_cache_destroy() function call.

The allocated cache is destroyed on kernel shutdown in an undefined manner.

This patch should define a proper destructor to deallocate resource in a
well-behaved, defined order.

Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Mickaël Salaün <mic@digikod.net>
Cc: Frederick Lawler <fred@cloudflare.com>

---
 security/integrity/iint.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index 8638976f7990..3f69eb702b2e 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -179,9 +179,16 @@ static int __init integrity_iintcache_init(void)
 			      0, SLAB_PANIC, init_once);
 	return 0;
 }
+
+static int __exit integrity_iintcache_release(void)
+{
+	kmem_cache_destroy(iint_cache);
+}
+
 DEFINE_LSM(integrity) = {
 	.name = "integrity",
 	.init = integrity_iintcache_init,
+	.release = integrity_iintcache_release,
 };
 
 
-- 
2.30.2

Re: [PATCH v1 1/2] LSM: add a release() hook for the clean exit cleanup of the LSM modules

[Andy Shevchenko]

On Sat, Mar 11, 2023 at 12:11:08AM +0100, Mirsad Goran Todorovac wrote:
> The LSM modules, namely integrity, do not have a clean way to deallocate
> resources allocated in the init() hook or later in their lifetime. The
> resources are destroyed on kernel shutdown in an undefined order.
> 
> This will allow a .release member per LSM module and calling proper
> destructors in a well-behaved order.

...

> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Mimi Zohar <zohar@linux.ibm.com>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: Thomas Weißschuh <linux@weissschuh.net>
> Cc: Casey Schaufler <casey@schaufler-ca.com>
> Cc: Christian Göttsche <cgzones@googlemail.com>
> Cc: Mickaël Salaün <mic@digikod.net>
> Cc: Frederick Lawler <fred@cloudflare.com>

As I told you, try to use my script instead, run it as

`ge2maintainer.sh -c 2 -v 2 HEAD~0 --annotate --cover-letter`

(assuming your 2 patches are on the top of the current branch
 in the Git tree of Linux kernel source code).

It will create a template for the cover letter, automatically
applies To and Cc lists based on the MAINTAINERS database and
sends them.

-- 
With Best Regards,
Andy Shevchenko