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Thu, 27 Aug 2020 07:44:21 -0700 (PDT) Subject: Re: [PATCH v5 0/3] io_uring: add restrictions to support untrusted applications and guests To: Stefano Garzarella Cc: Aleksa Sarai , Kernel Hardening , Jann Horn , io-uring@vger.kernel.org, Christian Brauner , linux-fsdevel@vger.kernel.org, Alexander Viro , Stefan Hajnoczi , linux-kernel@vger.kernel.org, Sargun Dhillon , Kees Cook , Jeff Moyer References: <20200827134044.82821-1-sgarzare@redhat.com> <2ded8df7-6dcb-ee8a-c1fd-e0c420b7b95d@kernel.dk> <20200827141002.an34n2nx6m4dfhce@steredhat.lan> <20200827144129.5yvu2icj7a5jfp3p@steredhat.lan> From: Jens Axboe Message-ID: Date: Thu, 27 Aug 2020 08:44:20 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200827144129.5yvu2icj7a5jfp3p@steredhat.lan> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 8/27/20 8:41 AM, Stefano Garzarella wrote: > On Thu, Aug 27, 2020 at 08:10:49AM -0600, Jens Axboe wrote: >> On 8/27/20 8:10 AM, Stefano Garzarella wrote: >>> On Thu, Aug 27, 2020 at 07:50:44AM -0600, Jens Axboe wrote: >>>> On 8/27/20 7:40 AM, Stefano Garzarella wrote: >>>>> v5: >>>>> - explicitly assigned enum values [Kees] >>>>> - replaced kmalloc/copy_from_user with memdup_user [kernel test robot] >>>>> - added Kees' R-b tags >>>>> >>>>> v4: https://lore.kernel.org/io-uring/20200813153254.93731-1-sgarzare@redhat.com/ >>>>> v3: https://lore.kernel.org/io-uring/20200728160101.48554-1-sgarzare@redhat.com/ >>>>> RFC v2: https://lore.kernel.org/io-uring/20200716124833.93667-1-sgarzare@redhat.com >>>>> RFC v1: https://lore.kernel.org/io-uring/20200710141945.129329-1-sgarzare@redhat.com >>>>> >>>>> Following the proposal that I send about restrictions [1], I wrote this series >>>>> to add restrictions in io_uring. >>>>> >>>>> I also wrote helpers in liburing and a test case (test/register-restrictions.c) >>>>> available in this repository: >>>>> https://github.com/stefano-garzarella/liburing (branch: io_uring_restrictions) >>>>> >>>>> Just to recap the proposal, the idea is to add some restrictions to the >>>>> operations (sqe opcode and flags, register opcode) to safely allow untrusted >>>>> applications or guests to use io_uring queues. >>>>> >>>>> The first patch changes io_uring_register(2) opcodes into an enumeration to >>>>> keep track of the last opcode available. >>>>> >>>>> The second patch adds IOURING_REGISTER_RESTRICTIONS opcode and the code to >>>>> handle restrictions. >>>>> >>>>> The third patch adds IORING_SETUP_R_DISABLED flag to start the rings disabled, >>>>> allowing the user to register restrictions, buffers, files, before to start >>>>> processing SQEs. >>>>> >>>>> Comments and suggestions are very welcome. >>>> >>>> Looks good to me, just a few very minor comments in patch 2. If you >>>> could fix those up, let's get this queued for 5.10. >>>> >>> >>> Sure, I'll fix the issues. This is great :-) >> >> Thanks! I'll pull in your liburing tests as well once we get the kernel >> side sorted. > > Yeah. Let me know if you'd prefer that I send patches on io-uring ML. > > About io-uring UAPI, do you think we should set explicitly the enum > values also for IOSQE_*_BIT and IORING_OP_*? > > I can send a separated patch for this. No, I actually think that change was a little bit silly. If you inadvertently renumber the enum in a patch, then tests would fail left and right. Hence I don't think this is a real risk. I'm fine with doing it for the addition, but doing it for the others is just going to cause stable headaches for patches. -- Jens Axboe