make sure that fchdir() won't accept referral points, etc.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/open.c b/fs/open.c
index 949cef29c3bba9395efd2e461d2078d0a9a9b47c..9f4bbd7cc51acb6467c86da806eebaa068fc9f69 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -459,20 +459,17 @@ out:
 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 {
        struct fd f = fdget_raw(fd);
-       struct inode *inode;
-       int error = -EBADF;
+       int error;
 
        error = -EBADF;
        if (!f.file)
                goto out;
 
-       inode = file_inode(f.file);
-
        error = -ENOTDIR;
-       if (!S_ISDIR(inode->i_mode))
+       if (!d_can_lookup(f.file->f_path.dentry))
                goto out_putf;
 
-       error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
+       error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
        if (!error)
                set_fs_pwd(current->fs, &f.file->f_path);
 out_putf: