[PATCH] match audit name data

Make more effort to detect previously collected names, so we don't log
multiple PATH records for a single filesystem object. Add
audit_inc_name_count() to reduce duplicate code.
Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

kernel/auditsc.c

@@ -78,11 +78,6 @@ extern int audit_enabled;
  * for saving names from getname(). */
 #define AUDIT_NAMES    20
 
-/* AUDIT_NAMES_RESERVED is the number of slots we reserve in the
- * audit_context from being used for nameless inodes from
- * path_lookup. */
-#define AUDIT_NAMES_RESERVED 7
-
 /* Indicates that audit should log the full pathname. */
 #define AUDIT_NAME_FULL -1
 
@@ -1343,6 +1338,28 @@ void audit_putname(const char *name)
 #endif
 }
 
+static int audit_inc_name_count(struct audit_context *context,
+				const struct inode *inode)
+{
+	if (context->name_count >= AUDIT_NAMES) {
+		if (inode)
+			printk(KERN_DEBUG "name_count maxed, losing inode data: "
+			       "dev=%02x:%02x, inode=%lu",
+			       MAJOR(inode->i_sb->s_dev),
+			       MINOR(inode->i_sb->s_dev),
+			       inode->i_ino);
+
+		else
+			printk(KERN_DEBUG "name_count maxed, losing inode data");
+		return 1;
+	}
+	context->name_count++;
+#if AUDIT_DEBUG
+	context->ino_count++;
+#endif
+	return 0;
+}
+
 /* Copy inode data into an audit_names. */
 static void audit_copy_inode(struct audit_names *name, const struct inode *inode)
 {
@@ -1380,13 +1397,10 @@ void __audit_inode(const char *name, const struct inode *inode)
 	else {
 		/* FIXME: how much do we care about inodes that have no
 		 * associated name? */
-		if (context->name_count >= AUDIT_NAMES - AUDIT_NAMES_RESERVED)
+		if (audit_inc_name_count(context, inode))
 			return;
-		idx = context->name_count++;
+		idx = context->name_count - 1;
 		context->names[idx].name = NULL;
-#if AUDIT_DEBUG
-		++context->ino_count;
-#endif
 	}
 	audit_copy_inode(&context->names[idx], inode);
 }
@@ -1410,7 +1424,7 @@ void __audit_inode_child(const char *dname, const struct inode *inode,
 {
 	int idx;
 	struct audit_context *context = current->audit_context;
-	const char *found_name = NULL;
+	const char *found_parent = NULL, *found_child = NULL;
 	int dirlen = 0;
 
 	if (!context->in_syscall)
@@ -1418,61 +1432,73 @@ void __audit_inode_child(const char *dname, const struct inode *inode,
 
 	/* determine matching parent */
 	if (!dname)
-		goto update_context;
-	for (idx = 0; idx < context->name_count; idx++)
-		if (context->names[idx].ino == parent->i_ino) {
-			const char *name = context->names[idx].name;
+		goto add_names;
 
-			if (!name)
-				continue;
+	/* parent is more likely, look for it first */
+	for (idx = 0; idx < context->name_count; idx++) {
+		struct audit_names *n = &context->names[idx];
 
-			if (audit_compare_dname_path(dname, name, &dirlen) == 0) {
-				context->names[idx].name_len = dirlen;
-				found_name = name;
-				break;
-			}
+		if (!n->name)
+			continue;
+
+		if (n->ino == parent->i_ino &&
+		    !audit_compare_dname_path(dname, n->name, &dirlen)) {
+			n->name_len = dirlen; /* update parent data in place */
+			found_parent = n->name;
+			goto add_names;
 		}
+	}
 
-update_context:
-	idx = context->name_count;
-	if (context->name_count == AUDIT_NAMES) {
-		printk(KERN_DEBUG "name_count maxed and losing %s\n",
-			found_name ?: "(null)");
-		return;
+	/* no matching parent, look for matching child */
+	for (idx = 0; idx < context->name_count; idx++) {
+		struct audit_names *n = &context->names[idx];
+
+		if (!n->name)
+			continue;
+
+		/* strcmp() is the more likely scenario */
+		if (!strcmp(dname, n->name) ||
+		     !audit_compare_dname_path(dname, n->name, &dirlen)) {
+			if (inode)
+				audit_copy_inode(n, inode);
+			else
+				n->ino = (unsigned long)-1;
+			found_child = n->name;
+			goto add_names;
+		}
 	}
-	context->name_count++;
-#if AUDIT_DEBUG
-	context->ino_count++;
-#endif
-	/* Re-use the name belonging to the slot for a matching parent directory.
-	 * All names for this context are relinquished in audit_free_names() */
-	context->names[idx].name = found_name;
-	context->names[idx].name_len = AUDIT_NAME_FULL;
-	context->names[idx].name_put = 0;	/* don't call __putname() */
-
-	if (!inode)
-		context->names[idx].ino = (unsigned long)-1;
-	else
-		audit_copy_inode(&context->names[idx], inode);
-
-	/* A parent was not found in audit_names, so copy the inode data for the
-	 * provided parent. */
-	if (!found_name) {
-		idx = context->name_count;
-		if (context->name_count == AUDIT_NAMES) {
-			printk(KERN_DEBUG
-				"name_count maxed and losing parent inode data: dev=%02x:%02x, inode=%lu",
-				MAJOR(parent->i_sb->s_dev),
-				MINOR(parent->i_sb->s_dev),
-				parent->i_ino);
+
+add_names:
+	if (!found_parent) {
+		if (audit_inc_name_count(context, parent))
 			return;
-		}
-		context->name_count++;
-#if AUDIT_DEBUG
-		context->ino_count++;
-#endif
+		idx = context->name_count - 1;
+		context->names[idx].name = NULL;
 		audit_copy_inode(&context->names[idx], parent);
 	}
+
+	if (!found_child) {
+		if (audit_inc_name_count(context, inode))
+			return;
+		idx = context->name_count - 1;
+
+		/* Re-use the name belonging to the slot for a matching parent
+		 * directory. All names for this context are relinquished in
+		 * audit_free_names() */
+		if (found_parent) {
+			context->names[idx].name = found_parent;
+			context->names[idx].name_len = AUDIT_NAME_FULL;
+			/* don't call __putname() */
+			context->names[idx].name_put = 0;
+		} else {
+			context->names[idx].name = NULL;
+		}
+
+		if (inode)
+			audit_copy_inode(&context->names[idx], inode);
+		else
+			context->names[idx].ino = (unsigned long)-1;
+	}
 }
 
 /**