[PATCH v3 4/5] Audit: multiple subject lsm values for netlabel

[Casey Schaufler <casey@schaufler-ca.com>]

Refactor audit_log_task_context(), creating a new audit_log_subj_ctx().
This is used in netlabel auditing to provide multiple subject security
contexts as necessary.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 include/linux/audit.h        |  7 +++++++
 kernel/audit.c               | 28 +++++++++++++++++++++-------
 net/netlabel/netlabel_user.c |  9 +--------
 3 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index b493ca5976cf..3402e3ca43c6 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -38,6 +38,7 @@ struct audit_tree;
 struct sk_buff;
 struct kern_ipc_perm;
 struct lsm_id;
+struct lsm_prop;
 
 struct audit_krule {
 	u32			pflags;
@@ -186,6 +187,7 @@ extern void		    audit_log_path_denied(int type,
 						  const char *operation);
 extern void		    audit_log_lost(const char *message);
 
+extern int audit_log_subj_ctx(struct audit_buffer *ab, struct lsm_prop *prop);
 extern int audit_log_task_context(struct audit_buffer *ab);
 extern void audit_log_task_info(struct audit_buffer *ab);
 
@@ -248,6 +250,11 @@ static inline void audit_log_key(struct audit_buffer *ab, char *key)
 { }
 static inline void audit_log_path_denied(int type, const char *operation)
 { }
+static inline int audit_log_subj_ctx(struct audit_buffer *ab,
+				     struct lsm_prop *prop)
+{
+	return 0;
+}
 static inline int audit_log_task_context(struct audit_buffer *ab)
 {
 	return 0;
diff --git a/kernel/audit.c b/kernel/audit.c
index 7ec3919ae925..8ce453f6dc7d 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2255,20 +2255,25 @@ static void audit_buffer_aux_end(struct audit_buffer *ab)
 	ab->skb = skb_peek(&ab->skb_list);
 }
 
-int audit_log_task_context(struct audit_buffer *ab)
+/**
+ * audit_log_subj_ctx - Add LSM subject information
+ * @ab: audit_buffer
+ * @prop: LSM subject properties.
+ *
+ * Add a subj= field and, if necessary, a AUDIT_MAC_TASK_CONTEXTS record.
+ */
+int audit_log_subj_ctx(struct audit_buffer *ab, struct lsm_prop *prop)
 {
-	struct lsm_prop prop;
 	struct lsm_context ctx;
 	bool space = false;
 	int error;
 	int i;
 
-	security_current_getlsmprop_subj(&prop);
-	if (!lsmprop_is_set(&prop))
+	if (!lsmprop_is_set(prop))
 		return 0;
 
 	if (audit_secctx_cnt < 2) {
-		error = security_lsmprop_to_secctx(&prop, &ctx, LSM_ID_UNDEF);
+		error = security_lsmprop_to_secctx(prop, &ctx, LSM_ID_UNDEF);
 		if (error < 0) {
 			if (error != -EINVAL)
 				goto error_path;
@@ -2285,7 +2290,7 @@ int audit_log_task_context(struct audit_buffer *ab)
 		goto error_path;
 
 	for (i = 0; i < audit_secctx_cnt; i++) {
-		error = security_lsmprop_to_secctx(&prop, &ctx,
+		error = security_lsmprop_to_secctx(prop, &ctx,
 						   audit_lsms[i]->id);
 		if (error < 0) {
 			if (error == -EOPNOTSUPP)
@@ -2305,9 +2310,18 @@ int audit_log_task_context(struct audit_buffer *ab)
 	return 0;
 
 error_path:
-	audit_panic("error in audit_log_task_context");
+	audit_panic("error in audit_log_subj_ctx");
 	return error;
 }
+EXPORT_SYMBOL(audit_log_subj_ctx);
+
+int audit_log_task_context(struct audit_buffer *ab)
+{
+	struct lsm_prop prop;
+
+	security_current_getlsmprop_subj(&prop);
+	return audit_log_subj_ctx(ab, &prop);
+}
 EXPORT_SYMBOL(audit_log_task_context);
 
 void audit_log_d_path_exe(struct audit_buffer *ab,
diff --git a/net/netlabel/netlabel_user.c b/net/netlabel/netlabel_user.c
index 6d6545297ee3..0da652844dd6 100644
--- a/net/netlabel/netlabel_user.c
+++ b/net/netlabel/netlabel_user.c
@@ -84,7 +84,6 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 					       struct netlbl_audit *audit_info)
 {
 	struct audit_buffer *audit_buf;
-	struct lsm_context ctx;
 
 	if (audit_enabled == AUDIT_OFF)
 		return NULL;
@@ -96,13 +95,7 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 	audit_log_format(audit_buf, "netlabel: auid=%u ses=%u",
 			 from_kuid(&init_user_ns, audit_info->loginuid),
 			 audit_info->sessionid);
-
-	if (lsmprop_is_set(&audit_info->prop) &&
-	    security_lsmprop_to_secctx(&audit_info->prop, &ctx,
-				       LSM_ID_UNDEF) > 0) {
-		audit_log_format(audit_buf, " subj=%s", ctx.context);
-		security_release_secctx(&ctx);
-	}
+	audit_log_subj_ctx(audit_buf, &audit_info->prop);
 
 	return audit_buf;
 }
-- 
2.47.0