NetLabel: honor the audit_enabled flag

The audit_enabled flag is used to signal when syscall auditing is to be
performed.  While NetLabel uses a Netlink interface instead of syscalls, it is
reasonable to consider the NetLabel Netlink interface as a form of syscall so
pay attention to the audit_enabled flag when generating audit messages in
NetLabel.
Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

net/netlabel/netlabel_cipso_v4.c

@@ -407,12 +407,14 @@ static int netlbl_cipsov4_add(struct sk_buff *skb, struct genl_info *info)
 
 	audit_buf = netlbl_audit_start_common(AUDIT_MAC_CIPSOV4_ADD,
 					      &audit_info);
+	if (audit_buf != NULL) {
 		audit_log_format(audit_buf,
 				 " cipso_doi=%u cipso_type=%s res=%u",
 				 doi,
 				 type_str,
 				 ret_val == 0 ? 1 : 0);
 		audit_log_end(audit_buf);
+	}
 
 	return ret_val;
 }
@@ -680,11 +682,13 @@ static int netlbl_cipsov4_remove(struct sk_buff *skb, struct genl_info *info)
 
 	audit_buf = netlbl_audit_start_common(AUDIT_MAC_CIPSOV4_DEL,
 					      &audit_info);
+	if (audit_buf != NULL) {
 		audit_log_format(audit_buf,
 				 " cipso_doi=%u res=%u",
 				 doi,
 				 ret_val == 0 ? 1 : 0);
 		audit_log_end(audit_buf);
+	}
 
 	return ret_val;
 }

net/netlabel/netlabel_domainhash.c

@@ -202,7 +202,6 @@ int netlbl_domhsh_add(struct netlbl_dom_map *entry,
 	int ret_val;
 	u32 bkt;
 	struct audit_buffer *audit_buf;
-	char *audit_domain;
 
 	switch (entry->type) {
 	case NETLBL_NLTYPE_UNLABELED:
@@ -243,12 +242,11 @@ int netlbl_domhsh_add(struct netlbl_dom_map *entry,
 	} else
 		ret_val = -EINVAL;
 
-	if (entry->domain != NULL)
-		audit_domain = entry->domain;
-	else
-		audit_domain = "(default)";
 	audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_ADD, audit_info);
-	audit_log_format(audit_buf, " nlbl_domain=%s", audit_domain);
+	if (audit_buf != NULL) {
+		audit_log_format(audit_buf,
+				 " nlbl_domain=%s",
+				 entry->domain ? entry->domain : "(default)");
 		switch (entry->type) {
 		case NETLBL_NLTYPE_UNLABELED:
 			audit_log_format(audit_buf, " nlbl_protocol=unlbl");
@@ -261,6 +259,7 @@ int netlbl_domhsh_add(struct netlbl_dom_map *entry,
 		}
 		audit_log_format(audit_buf, " res=%u", ret_val == 0 ? 1 : 0);
 		audit_log_end(audit_buf);
+	}
 
 	rcu_read_unlock();
 
@@ -310,7 +309,6 @@ int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
 	int ret_val = -ENOENT;
 	struct netlbl_dom_map *entry;
 	struct audit_buffer *audit_buf;
-	char *audit_domain;
 
 	rcu_read_lock();
 	if (domain != NULL)
@@ -348,16 +346,14 @@ int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
 		spin_unlock(&netlbl_domhsh_def_lock);
 	}
 
-	if (entry->domain != NULL)
-		audit_domain = entry->domain;
-	else
-		audit_domain = "(default)";
 	audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_DEL, audit_info);
+	if (audit_buf != NULL) {
 		audit_log_format(audit_buf,
 				 " nlbl_domain=%s res=%u",
-			 audit_domain,
+				 entry->domain ? entry->domain : "(default)",
 				 ret_val == 0 ? 1 : 0);
 		audit_log_end(audit_buf);
+	}
 
 	if (ret_val == 0)
 		call_rcu(&entry->rcu, netlbl_domhsh_free_entry);

net/netlabel/netlabel_unlabeled.c

@@ -35,6 +35,7 @@
 #include <linux/socket.h>
 #include <linux/string.h>
 #include <linux/skbuff.h>
+#include <linux/audit.h>
 #include <net/sock.h>
 #include <net/netlink.h>
 #include <net/genetlink.h>
@@ -92,8 +93,11 @@ static void netlbl_unlabel_acceptflg_set(u8 value,
 
 	audit_buf = netlbl_audit_start_common(AUDIT_MAC_UNLBL_ALLOW,
 					      audit_info);
-	audit_log_format(audit_buf, " unlbl_accept=%u old=%u", value, old_val);
+	if (audit_buf != NULL) {
+		audit_log_format(audit_buf,
+				 " unlbl_accept=%u old=%u", value, old_val);
 		audit_log_end(audit_buf);
+	}
 }
 
 /*

net/netlabel/netlabel_user.c

@@ -46,6 +46,10 @@
 #include "netlabel_cipso_v4.h"
 #include "netlabel_user.h"
 
+/* do not do any auditing if audit_enabled == 0, see kernel/audit.c for
+ * details */
+extern int audit_enabled;
+
 /*
  * NetLabel NETLINK Setup Functions
  */
@@ -101,6 +105,9 @@ struct audit_buffer *netlbl_audit_start_common(int type,
 	char *secctx;
 	u32 secctx_len;
 
+	if (audit_enabled == 0)
+		return NULL;
+
 	audit_buf = audit_log_start(audit_ctx, GFP_ATOMIC, type);
 	if (audit_buf == NULL)
 		return NULL;