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Message-ID: <20200721104009.lg626hmls5y6ihdr@steredhat>
Date: Tue, 21 Jul 2020 12:40:09 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Jens Axboe <axboe@...nel.dk>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Kees Cook <keescook@...omium.org>, Aleksa Sarai <asarai@...e.de>,
Stefan Hajnoczi <stefanha@...hat.com>,
Christian Brauner <christian.brauner@...ntu.com>,
Sargun Dhillon <sargun@...gun.me>, Jann Horn <jannh@...gle.com>,
io-uring@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Jeff Moyer <jmoyer@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC v2 2/3] io_uring: add IOURING_REGISTER_RESTRICTIONS
opcode
On Thu, Jul 16, 2020 at 03:26:51PM -0600, Jens Axboe wrote:
> On 7/16/20 6:48 AM, Stefano Garzarella wrote:
> > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> > index efc50bd0af34..0774d5382c65 100644
> > --- a/include/uapi/linux/io_uring.h
> > +++ b/include/uapi/linux/io_uring.h
> > @@ -265,6 +265,7 @@ enum {
> > IORING_REGISTER_PROBE,
> > IORING_REGISTER_PERSONALITY,
> > IORING_UNREGISTER_PERSONALITY,
> > + IORING_REGISTER_RESTRICTIONS,
> >
> > /* this goes last */
> > IORING_REGISTER_LAST
> > @@ -293,4 +294,30 @@ struct io_uring_probe {
> > struct io_uring_probe_op ops[0];
> > };
> >
> > +struct io_uring_restriction {
> > + __u16 opcode;
> > + union {
> > + __u8 register_op; /* IORING_RESTRICTION_REGISTER_OP */
> > + __u8 sqe_op; /* IORING_RESTRICTION_SQE_OP */
> > + };
> > + __u8 resv;
> > + __u32 resv2[3];
> > +};
> > +
> > +/*
> > + * io_uring_restriction->opcode values
> > + */
> > +enum {
> > + /* Allow an io_uring_register(2) opcode */
> > + IORING_RESTRICTION_REGISTER_OP,
> > +
> > + /* Allow an sqe opcode */
> > + IORING_RESTRICTION_SQE_OP,
> > +
> > + /* Only allow fixed files */
> > + IORING_RESTRICTION_FIXED_FILES_ONLY,
> > +
> > + IORING_RESTRICTION_LAST
> > +};
> > +
>
> Not sure I totally love this API. Maybe it'd be cleaner to have separate
> ops for this, instead of muxing it like this. One for registering op
> code restrictions, and one for disallowing other parts (like fixed
> files, etc).
>
> I think that would look a lot cleaner than the above.
>
Talking with Stefan, an alternative, maybe more near to your suggestion,
would be to remove the 'struct io_uring_restriction' and add the
following register ops:
/* Allow an sqe opcode */
IORING_REGISTER_RESTRICTION_SQE_OP
/* Allow an io_uring_register(2) opcode */
IORING_REGISTER_RESTRICTION_REG_OP
/* Register IORING_RESTRICTION_* */
IORING_REGISTER_RESTRICTION_OP
enum {
/* Only allow fixed files */
IORING_RESTRICTION_FIXED_FILES_ONLY,
IORING_RESTRICTION_LAST
}
We can also enable restriction only when the rings started, to avoid to
register IORING_REGISTER_ENABLE_RINGS opcode. Once rings are started,
the restrictions cannot be changed or disabled.
If you agree, I'll send a v3 following this.
Thanks,
Stefano
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