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Tue, 21 Jul 2020 03:40:14 -0700 (PDT) Date: Tue, 21 Jul 2020 12:40:09 +0200 From: Stefano Garzarella To: Jens Axboe Cc: Alexander Viro , Kernel Hardening , Kees Cook , Aleksa Sarai , Stefan Hajnoczi , Christian Brauner , Sargun Dhillon , Jann Horn , io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jeff Moyer , linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC v2 2/3] io_uring: add IOURING_REGISTER_RESTRICTIONS opcode Message-ID: <20200721104009.lg626hmls5y6ihdr@steredhat> References: <20200716124833.93667-1-sgarzare@redhat.com> <20200716124833.93667-3-sgarzare@redhat.com> <0fbb0393-c14f-3576-26b1-8bb22d2e0615@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0fbb0393-c14f-3576-26b1-8bb22d2e0615@kernel.dk> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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