[PATCH v4 2/5] fs: Add fchmodat2()

[dalias at libc.org]

On Thu, Jul 27, 2023 at 09:01:06AM +0000, David Laight wrote:
> From: Aleksa Sarai
> > Sent: 25 July 2023 17:36
> ....
> > 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