[PATCH] audit: add fields to exclude filter by reusing user filter

[Richard Guy Briggs]

RFE: add additional fields for use in audit filter exclude rules
https://github.com/linux-audit/audit-kernel/issues/5

Re-factor audit_filter_type() to use audit_filter_user_rules() to enable
exclude filter to additionally filter on PID, UID, GID, AUID,
LOGINUID_SET, SUBJ_*.

Add check in audit_filter_user() to quit early if list is empty.

Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
---
 kernel/auditfilter.c |   22 +++++++++-------------
 1 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 96c9a1b..515c752 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1358,6 +1358,9 @@ int audit_filter_user(int type)
 	ret = 1; /* Audit by default */
 
 	rcu_read_lock();
+	if (list_empty(&audit_filter_list[AUDIT_FILTER_USER]))
+		goto unlock_and_return;
+
 	list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
 		rc = audit_filter_user_rules(&e->rule, type, &state);
 		if (rc) {
@@ -1366,13 +1369,14 @@ int audit_filter_user(int type)
 			break;
 		}
 	}
+unlock_and_return:
 	rcu_read_unlock();
-
 	return ret;
 }
 
 int audit_filter_type(int type)
 {
+	enum audit_state state = AUDIT_DISABLED;
 	struct audit_entry *e;
 	int result = 0;
 
@@ -1380,19 +1384,11 @@ int audit_filter_type(int type)
 	if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
 		goto unlock_and_return;
 
-	list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
-				list) {
-		int i;
-		for (i = 0; i < e->rule.field_count; i++) {
-			struct audit_field *f = &e->rule.fields[i];
-			if (f->type == AUDIT_MSGTYPE) {
-				result = audit_comparator(type, f->op, f->val);
-				if (!result)
-					break;
-			}
+	list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE], list) {
+		if (audit_filter_user_rules(&e->rule, type, &state) == 1) {
+			result = 1;
+			break;
 		}
-		if (result)
-			goto unlock_and_return;
 	}
 unlock_and_return:
 	rcu_read_unlock();
-- 
1.7.1