[PATCH] add a vfs_permission helper
Most permission() calls have a struct nameidata * available. This helper
takes that as an argument and thus makes sure we pass it down for lookup
intents and prepares for per-mount read-only support where we need a struct
vfsmount for checking whether a file is writeable.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/namei.c b/fs/namei.c
index b3f8a19..25e4ab4 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -256,6 +256,21 @@
return security_inode_permission(inode, mask, nd);
}
+/**
+ * vfs_permission - check for access rights to a given path
+ * @nd: lookup result that describes the path
+ * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Used to check for read/write/execute permissions on a path.
+ * We use "fsuid" for this, letting us set arbitrary permissions
+ * for filesystem access without changing the "normal" uids which
+ * are used for other things.
+ */
+int vfs_permission(struct nameidata *nd, int mask)
+{
+ return permission(nd->dentry->d_inode, mask, nd);
+}
+
/*
* get_write_access() gets write permission for a file.
* put_write_access() releases this write permission.
@@ -765,9 +780,8 @@
nd->flags |= LOOKUP_CONTINUE;
err = exec_permission_lite(inode, nd);
- if (err == -EAGAIN) {
- err = permission(inode, MAY_EXEC, nd);
- }
+ if (err == -EAGAIN)
+ err = vfs_permission(nd, MAY_EXEC);
if (err)
break;
@@ -1407,7 +1421,7 @@
if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
return -EISDIR;
- error = permission(inode, acc_mode, nd);
+ error = vfs_permission(nd, acc_mode);
if (error)
return error;
@@ -2536,6 +2550,7 @@
EXPORT_SYMBOL(path_release);
EXPORT_SYMBOL(path_walk);
EXPORT_SYMBOL(permission);
+EXPORT_SYMBOL(vfs_permission);
EXPORT_SYMBOL(unlock_rename);
EXPORT_SYMBOL(vfs_create);
EXPORT_SYMBOL(vfs_follow_link);