vfs: Distinguish between full xattr names and proper prefixes
Add an additional "name" field to struct xattr_handler. When the name
is set, the handler matches attributes with exactly that name. When the
prefix is set instead, the handler matches attributes with the given
prefix and with a non-empty suffix.
This patch should avoid bugs like the one fixed in commit c361016a in
the future.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index 45fa345..03c847f 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -19,7 +19,13 @@
struct inode;
struct dentry;
+/*
+ * struct xattr_handler: When @name is set, match attributes with exactly that
+ * name. When @prefix is set instead, match attributes with that prefix and
+ * with a non-empty suffix.
+ */
struct xattr_handler {
+ const char *name;
const char *prefix;
int flags; /* fs private flags */
size_t (*list)(const struct xattr_handler *, struct dentry *dentry,
@@ -54,6 +60,11 @@
ssize_t vfs_getxattr_alloc(struct dentry *dentry, const char *name,
char **xattr_value, size_t size, gfp_t flags);
+static inline const char *xattr_prefix(const struct xattr_handler *handler)
+{
+ return handler->prefix ?: handler->name;
+}
+
struct simple_xattrs {
struct list_head head;
spinlock_t lock;