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

"[email protected]" <[email protected]> Thu, 27 Jul 2023 12:31:04 -0400

Newsgroups	gmane.linux.file-systems,gmane.linux.kernel,gmane.linux.kernel.api,gmane.linux.ports.alpha,gmane.linux.kernel.cross-arch,gmane.linux.ports.ia64,gmane.linux.ports.mips,gmane.linux.ports.parisc,gmane.linux.ports.sh.devel,gmane.linux.ports.ppc64.devel,gmane.linux.ports.sparc
Message-ID	<[email protected]>

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