audit: fix filename matching in __audit_inode() and __audit_inode_child()

In all likelihood there were some subtle, and perhaps not so subtle,
bugs with filename matching in audit_inode() and audit_inode_child()
for some time, however, recent changes to the audit filename code have
definitely broken the filename matching code. The breakage could
result in duplicate filenames in the audit log and other odd audit
record entries. This patch fixes the filename matching code and
restores some sanity to the filename audit records.

CC: [e-mail]
CC: [e-mail]
Signed-off-by: Paul Moore <[e-mail]>
Signed-off-by: Al Viro <[e-mail]>

kernel/auditsc.c

···
 	/* The struct filename _must_ have a populated ->name */
 	BUG_ON(!name->name);
 #endif
+
 	/*
 	 * If we have a pointer to an audit_names entry already, then we can
 	 * just use it directly if the type is correct.
···
 	}
 
 	list_for_each_entry_reverse(n, &context->names_list, list) {
-		if (!n->name || strcmp(n->name->name, name->name))
+		if (n->ino) {
+			/* valid inode number, use that for the comparison */
+			if (n->ino != inode->i_ino ||
+			    n->dev != inode->i_sb->s_dev)
+				continue;
+		} else if (n->name) {
+			/* inode number has not been set, check the name */
+			if (strcmp(n->name->name, name->name))
+				continue;
+		} else
+			/* no inode and no name (?!) ... this is odd ... */
 			continue;
 
 		/* match the correct record type */
···
 
 	/* look for a parent entry first */
 	list_for_each_entry(n, &context->names_list, list) {
-		if (!n->name || n->type != AUDIT_TYPE_PARENT)
+		if (!n->name ||
+		    (n->type != AUDIT_TYPE_PARENT &&
+		     n->type != AUDIT_TYPE_UNKNOWN))
 			continue;
 
-		if (n->ino == parent->i_ino &&
-		    !audit_compare_dname_path(dname, n->name->name, n->name_len)) {
+		if (n->ino == parent->i_ino && n->dev == parent->i_sb->s_dev &&
+		    !audit_compare_dname_path(dname,
+					      n->name->name, n->name_len)) {
+			if (n->type == AUDIT_TYPE_UNKNOWN)
+				n->type = AUDIT_TYPE_PARENT;
 			found_parent = n;
 			break;
 		}
···
 	/* is there a matching child entry? */
 	list_for_each_entry(n, &context->names_list, list) {
 		/* can only match entries that have a name */
-		if (!n->name || n->type != type)
-			continue;
-
-		/* if we found a parent, make sure this one is a child of it */
-		if (found_parent && (n->name != found_parent->name))
+		if (!n->name ||
+		    (n->type != type && n->type != AUDIT_TYPE_UNKNOWN))
 			continue;
 
 		if (!strcmp(dname, n->name->name) ||
···
 						found_parent ?
 						found_parent->name_len :
 						AUDIT_NAME_FULL)) {
+			if (n->type == AUDIT_TYPE_UNKNOWN)
+				n->type = type;
 			found_child = n;
 			break;
 		}
···
 			found_child->name_put = false;
 		}
 	}
+
 	if (inode)
 		audit_copy_inode(found_child, dentry, inode);
 	else