On Thu, Jul 27, 2023 at 09:01:06AM +0000, David Laight wrote:

From: Aleksa Sarai

quoted

Sent: 25 July 2023 17:36

....

quoted

We almost certainly want to support AT_EMPTY_PATH at the same time.
Otherwise userspace will still need to go through /proc when trying to
chmod a file handle they have.

That can't be allowed.

Just because a process has a file open and write access to
the directory that contains it doesn't mean they are allowed
to change the file permissions.

They also need directory search access from a directory
they have open through to the containing directory.

Am I missing something? How is this different from fchmod?

Rich