Re: [RFC] struct filename, io_uring and audit troubles

[Al Viro <viro@zeniv.linux.org.uk>]

On Wed, Sep 25, 2024 at 12:01:01AM -0600, Jens Axboe wrote:

> The normal policy is that anything that is read-only should remain
> stable after ->prep() has been called, so that ->issue() can use it.
> That means the application can keep it on-stack as long as it's valid
> until io_uring_submit() returns. For structs/buffers that are copied to
> after IO, those the application obviously need to keep around until they
> see a completion for that request.  So yes, for the xattr cases where the
> struct is copied to at completion time, those do not need to be stable
> after ->prep(), could be handled purely on the ->issue() side.

Hmm...  Nothing in xattr is copied in both directions, actually.

AFAICS, the only copy-in you leave to ->issue() is the data for write
and sendmsg and ->msg_control for sendmsg.  Wait, there's that ioctl-like
mess you've got, so anything that feels like doing (seems to include
at least setsockopt)...  Oh, well...