[RFC PATCH v2 02/14] lsm: Add audit_log_lsm_data() helper

Mickaël Salaün posted 14 patches 1 month ago
There is a newer version of this series
[RFC PATCH v2 02/14] lsm: Add audit_log_lsm_data() helper
Posted by Mickaël Salaün 1 month ago
Extract code from dump_common_audit_data() into the audit_log_lsm_data()
helper. This helps reuse common LSM audit data while not abusing
AUDIT_AVC records because of the common_lsm_audit() helper.

Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: James Morris <jmorris@namei.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20241022161009.982584-3-mic@digikod.net
---

Changes since v1:
* Fix commit message (spotted by Paul).
* Constify dump_common_audit_data()'s and audit_log_lsm_data()'s "a"
  argument.
* Fix build without CONFIG_NET: see previous patch.
---
 include/linux/lsm_audit.h |  8 ++++++++
 security/lsm_audit.c      | 27 ++++++++++++++++++---------
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
index c2b01380262c..b62769a7c5fa 100644
--- a/include/linux/lsm_audit.h
+++ b/include/linux/lsm_audit.h
@@ -130,6 +130,9 @@ void common_lsm_audit(struct common_audit_data *a,
 	void (*pre_audit)(struct audit_buffer *, void *),
 	void (*post_audit)(struct audit_buffer *, void *));
 
+void audit_log_lsm_data(struct audit_buffer *ab,
+			const struct common_audit_data *a);
+
 #else /* CONFIG_AUDIT */
 
 static inline void common_lsm_audit(struct common_audit_data *a,
@@ -138,6 +141,11 @@ static inline void common_lsm_audit(struct common_audit_data *a,
 {
 }
 
+static inline void audit_log_lsm_data(struct audit_buffer *ab,
+			const struct common_audit_data *a)
+{
+}
+
 #endif /* CONFIG_AUDIT */
 
 #endif
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 849e832719e2..de29ce8ff708 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -189,16 +189,13 @@ static inline void print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
 }
 
 /**
- * dump_common_audit_data - helper to dump common audit data
+ * audit_log_lsm_data - helper to log common LSM audit data
  * @ab : the audit buffer
  * @a : common audit data
- *
  */
-static void dump_common_audit_data(struct audit_buffer *ab,
-				   struct common_audit_data *a)
+void audit_log_lsm_data(struct audit_buffer *ab,
+			const struct common_audit_data *a)
 {
-	char comm[sizeof(current->comm)];
-
 	/*
 	 * To keep stack sizes in check force programmers to notice if they
 	 * start making this union too large!  See struct lsm_network_audit
@@ -206,9 +203,6 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 	 */
 	BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
 
-	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
-	audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
-
 	switch (a->type) {
 	case LSM_AUDIT_DATA_NONE:
 		return;
@@ -428,6 +422,21 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 	} /* switch (a->type) */
 }
 
+/**
+ * dump_common_audit_data - helper to dump common audit data
+ * @ab : the audit buffer
+ * @a : common audit data
+ */
+static void dump_common_audit_data(struct audit_buffer *ab,
+				   const struct common_audit_data *a)
+{
+	char comm[sizeof(current->comm)];
+
+	audit_log_format(ab, " pid=%d comm=", task_tgid_nr(current));
+	audit_log_untrustedstring(ab, memcpy(comm, current->comm, sizeof(comm)));
+	audit_log_lsm_data(ab, a);
+}
+
 /**
  * common_lsm_audit - generic LSM auditing function
  * @a:  auxiliary audit data
-- 
2.47.0

Re: [RFC PATCH v2 02/14] lsm: Add audit_log_lsm_data() helper
Posted by Paul Moore 1 month ago
On Tue, Oct 22, 2024 at 12:10 PM Mickaël Salaün <mic@digikod.net> wrote:
>
> Extract code from dump_common_audit_data() into the audit_log_lsm_data()
> helper. This helps reuse common LSM audit data while not abusing
> AUDIT_AVC records because of the common_lsm_audit() helper.
>
> Cc: Casey Schaufler <casey@schaufler-ca.com>
> Cc: James Morris <jmorris@namei.org>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: Serge E. Hallyn <serge@hallyn.com>
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
> Link: https://lore.kernel.org/r/20241022161009.982584-3-mic@digikod.net
> ---
>
> Changes since v1:
> * Fix commit message (spotted by Paul).
> * Constify dump_common_audit_data()'s and audit_log_lsm_data()'s "a"
>   argument.
> * Fix build without CONFIG_NET: see previous patch.
> ---
>  include/linux/lsm_audit.h |  8 ++++++++
>  security/lsm_audit.c      | 27 ++++++++++++++++++---------
>  2 files changed, 26 insertions(+), 9 deletions(-)

While not a fix like 1/14, reducing AUDIT_AVC reuse is a reasonable
goal.  Merged into lsm/dev, thanks!

-- 
paul-moore.com
Re: [RFC PATCH v2 02/14] lsm: Add audit_log_lsm_data() helper
Posted by Paul Moore 1 month ago
On Tue, Oct 22, 2024 at 8:07 PM Paul Moore <paul@paul-moore.com> wrote:
>
> On Tue, Oct 22, 2024 at 12:10 PM Mickaël Salaün <mic@digikod.net> wrote:
> >
> > Extract code from dump_common_audit_data() into the audit_log_lsm_data()
> > helper. This helps reuse common LSM audit data while not abusing
> > AUDIT_AVC records because of the common_lsm_audit() helper.
> >
> > Cc: Casey Schaufler <casey@schaufler-ca.com>
> > Cc: James Morris <jmorris@namei.org>
> > Cc: Paul Moore <paul@paul-moore.com>
> > Cc: Serge E. Hallyn <serge@hallyn.com>
> > Signed-off-by: Mickaël Salaün <mic@digikod.net>
> > Link: https://lore.kernel.org/r/20241022161009.982584-3-mic@digikod.net
> > ---
> >
> > Changes since v1:
> > * Fix commit message (spotted by Paul).
> > * Constify dump_common_audit_data()'s and audit_log_lsm_data()'s "a"
> >   argument.
> > * Fix build without CONFIG_NET: see previous patch.
> > ---
> >  include/linux/lsm_audit.h |  8 ++++++++
> >  security/lsm_audit.c      | 27 ++++++++++++++++++---------
> >  2 files changed, 26 insertions(+), 9 deletions(-)
>
> While not a fix like 1/14, reducing AUDIT_AVC reuse is a reasonable
> goal.  Merged into lsm/dev, thanks!

I'm also going to have to remove this patch from lsm/dev due to
problems uncovered by the kernel test robot.

-- 
paul-moore.com