linux-kernel - Re: [PATCH RFC v2 1/3] io_uring: use an enumeration for io_uring

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <76879432-745d-a5ca-b171-b1391b926ea2@kernel.dk>
Date:   Thu, 16 Jul 2020 14:51:26 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Pavel Begunkov <asml.silence@...il.com>,
        Stefano Garzarella <sgarzare@...hat.com>
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 1/3] io_uring: use an enumeration for
 io_uring_register(2) opcodes

On 7/16/20 2:47 PM, Pavel Begunkov wrote:
> On 16/07/2020 23:42, Jens Axboe wrote:
>> On 7/16/20 2:16 PM, Pavel Begunkov wrote:
>>> On 16/07/2020 15:48, Stefano Garzarella wrote:
>>>> The enumeration allows us to keep track of the last
>>>> io_uring_register(2) opcode available.
>>>>
>>>> Behaviour and opcodes names don't change.
>>>>
>>>> Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
>>>> ---
>>>>  include/uapi/linux/io_uring.h | 27 ++++++++++++++++-----------
>>>>  1 file changed, 16 insertions(+), 11 deletions(-)
>>>>
>>>> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
>>>> index 7843742b8b74..efc50bd0af34 100644
>>>> --- a/include/uapi/linux/io_uring.h
>>>> +++ b/include/uapi/linux/io_uring.h
>>>> @@ -253,17 +253,22 @@ struct io_uring_params {
>>>>  /*
>>>>   * io_uring_register(2) opcodes and arguments
>>>>   */
>>>> -#define IORING_REGISTER_BUFFERS		0
>>>> -#define IORING_UNREGISTER_BUFFERS	1
>>>> -#define IORING_REGISTER_FILES		2
>>>> -#define IORING_UNREGISTER_FILES		3
>>>> -#define IORING_REGISTER_EVENTFD		4
>>>> -#define IORING_UNREGISTER_EVENTFD	5
>>>> -#define IORING_REGISTER_FILES_UPDATE	6
>>>> -#define IORING_REGISTER_EVENTFD_ASYNC	7
>>>> -#define IORING_REGISTER_PROBE		8
>>>> -#define IORING_REGISTER_PERSONALITY	9
>>>> -#define IORING_UNREGISTER_PERSONALITY	10
>>>> +enum {
>>>> +	IORING_REGISTER_BUFFERS,
>>>> +	IORING_UNREGISTER_BUFFERS,
>>>> +	IORING_REGISTER_FILES,
>>>> +	IORING_UNREGISTER_FILES,
>>>> +	IORING_REGISTER_EVENTFD,
>>>> +	IORING_UNREGISTER_EVENTFD,
>>>> +	IORING_REGISTER_FILES_UPDATE,
>>>> +	IORING_REGISTER_EVENTFD_ASYNC,
>>>> +	IORING_REGISTER_PROBE,
>>>> +	IORING_REGISTER_PERSONALITY,
>>>> +	IORING_UNREGISTER_PERSONALITY,
>>>> +
>>>> +	/* this goes last */
>>>> +	IORING_REGISTER_LAST
>>>> +};
>>>
>>> It breaks userspace API. E.g.
>>>
>>> #ifdef IORING_REGISTER_BUFFERS
>>
>> It can, yes, but we have done that in the past. In this one, for
> 
> Ok, if nobody on the userspace side cares, then better to do that
> sooner than later.
> 
> 
>> example:
>>
>> commit 9e3aa61ae3e01ce1ce6361a41ef725e1f4d1d2bf (tag: io_uring-5.5-20191212)
>> Author: Jens Axboe <axboe@...nel.dk>
>> Date:   Wed Dec 11 15:55:43 2019 -0700
>>
>>     io_uring: ensure we return -EINVAL on unknown opcod
>>
>> But it would be safer/saner to do this like we have the done the IOSQE_
>> flags.
> 
> IOSQE_ are a bitmask, but this would look peculiar
> 
> enum {
> 	__IORING_REGISTER_BUFFERS,
> 	...
> };
> define IORING_REGISTER_BUFFERS __IORING_REGISTER_BUFFERS

Yeah true of course, that won't really work for this case at all.

That said, I don't think it's a huge deal to turn it into an enum.


-- 
Jens Axboe