1 files changed, 41 insertions, 13 deletions

diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index 42becbc1ce33..7ba8478f599e 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -67,6 +67,46 @@ static u32 smack_next_secid = 10;
 int log_policy = SMACK_AUDIT_DENIED;
 
 /**
+ * smk_access_entry - look up matching access rule
+ * @subject_label: a pointer to the subject's Smack label
+ * @object_label: a pointer to the object's Smack label
+ *
+ * This function looks up the subject/object pair in the
+ * access rule list and returns pointer to the matching rule if found,
+ * NULL otherwise.
+ *
+ * NOTE:
+ * Even though Smack labels are usually shared on smack_list
+ * labels that come in off the network can't be imported
+ * and added to the list for locking reasons.
+ *
+ * Therefore, it is necessary to check the contents of the labels,
+ * not just the pointer values. Of course, in most cases the labels
+ * will be on the list, so checking the pointers may be a worthwhile
+ * optimization.
+ */
+int smk_access_entry(char *subject_label, char *object_label)
+{
+	u32 may = MAY_NOT;
+	struct smack_rule *srp;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(srp, &smack_rule_list, list) {
+		if (srp->smk_subject == subject_label ||
+		    strcmp(srp->smk_subject, subject_label) == 0) {
+			if (srp->smk_object == object_label ||
+			    strcmp(srp->smk_object, object_label) == 0) {
+				may = srp->smk_access;
+				break;
+			}
+		}
+	}
+	rcu_read_unlock();
+
+	return may;
+}
+
+/**
  * smk_access - determine if a subject has a specific access to an object
  * @subject_label: a pointer to the subject's Smack label
  * @object_label: a pointer to the object's Smack label
@@ -90,7 +130,6 @@ int smk_access(char *subject_label, char *object_label, int request,
 	       struct smk_audit_info *a)
 {
 	u32 may = MAY_NOT;
-	struct smack_rule *srp;
 	int rc = 0;
 
 	/*
@@ -144,18 +183,7 @@ int smk_access(char *subject_label, char *object_label, int request,
 	 * access (e.g. read is included in readwrite) it's
 	 * good.
 	 */
-	rcu_read_lock();
-	list_for_each_entry_rcu(srp, &smack_rule_list, list) {
-		if (srp->smk_subject == subject_label ||
-		    strcmp(srp->smk_subject, subject_label) == 0) {
-			if (srp->smk_object == object_label ||
-			    strcmp(srp->smk_object, object_label) == 0) {
-				may = srp->smk_access;
-				break;
-			}
-		}
-	}
-	rcu_read_unlock();
+	may = smk_access_entry(subject_label, object_label);
 	/*
 	 * This is a bit map operation.
 	 */