Re: [RFC PATCH] fs: allow opening overlayfs/erofs layers through O_ALT

On 2026-07-20 11:22 +0200, Miklos Szeredi wrote:
> On Sun, 19 Jul 2026 at 16:13, Andy Lutomirski <[email protected]> wrote:
> 
> > This gives me the willies a bit.  It's very cool, but it has some
> > potential security issues that I think we need to watch out for.  As
> > sort-of prior art, NTFS supports alternate streams and Reiser4, ahem,
> > supported files-as-directories.
> 
> I realized that we can keep the creepiness factor minimal by
> introducing this first in procfs only.   That way zero changes are
> needed in the path lookup code:
> 
> sprintf(buf, "/proc/self/fd-alt/%d/%s", base_fd, alt_path);
> alt_fd = open(buf, O_PATH);

I'm still vehemently opposed to stuffing more creepy apis into procfs.
So this gets clear opposition from me.