[PATCH v5 01/24] lsm: Add audit_log_lsm_data() helper

Mickaël Salaün
2025-01-31T16:31:18Z

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: Serge E. Hallyn <serge@hallyn.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Depends-on: 7ccbe076d987 ("lsm: Only build lsm_audit.c if CONFIG_SECURITY and CONFIG_AUDIT are set")
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20250131163059.1139617-2-mic@digikod.net
---

Changes since v4:
- Add Depends-on tag.

Changes since v3:
- Rebase on top of the v6.13's get_task_comm() fix.
- Add Acked-by Paul.

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 e13d2f947b51..bddd694f7c4c 100644
--- a/include/linux/lsm_audit.h
+++ b/include/linux/lsm_audit.h
@@ -132,6 +132,9 @@ 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,
@@ -140,6 +143,11 @@ 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 52db886dbba8..a61c7ebdb6a7 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, get_task_comm(comm, current));
-
switch (a->type) {
case LSM_AUDIT_DATA_NONE:
return;
@@ -431,6 +425,21 @@ 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, get_task_comm(comm, current));
+ audit_log_lsm_data(ab, a);
+}
+
/**
* common_lsm_audit - generic LSM auditing function
* @a: auxiliary audit data
--
2.48.1