Re: [PATCH 24/32] vfs: syscall: Add fsopen() to prepare for superblock creation [ver #9]

On Jul 12, 2018, at 1:23 PM, David Howells [off-list ref] wrote:

Linus Torvalds [off-list ref] wrote:

quoted

Don't play games with override_creds. It's wrong.

You have to use file->f_creds - no games, no garbage.

You missed the point.

My suggestion was to use override_creds() to impose the appropriate creds at
the top, be that file->f_creds or fs_context->creds (they would be the same in
any case).

I think it should be a new syscall and use current’s creds. No override needed.

Btw, do we protect sysfs, debugfs, tracefs, procfs, etc. writes against
splice?  Some of the things in debugfs are really icky, allowing you to muck
directly with hardware.

We try. It has been a perennial source of severe bugs.

This is part of why I’d like to see splice() be an opt in. Also, it’s a major step toward getting rid of set_fs().