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From: Stefan Metzmacher <[email protected]>
To: Pavel Begunkov <[email protected]>,
	Jens Axboe <[email protected]>,
	[email protected]
Subject: Re: [PATCH 5.11] io_uring: don't take fs for recvmsg/sendmsg
Date: Wed, 18 Nov 2020 17:27:18 +0100	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>


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Am 07.11.20 um 17:07 schrieb Pavel Begunkov:
> On 07/11/2020 16:02, Pavel Begunkov wrote:
>> On 07/11/2020 13:46, Stefan Metzmacher wrote:
>>> Hi Pavel,
>>>
>>>> We don't even allow not plain data msg_control, which is disallowed in __sys_{send,revb}msg_sock().
>>>
>>> Can't we better remove these checks and allow msg_control?
>>> For me it's a limitation that I would like to be removed.
>>
>> We can grab fs only in specific situations as you mentioned, by e.g.
>> adding a switch(opcode) in io_prep_async_work(), but that's the easy
>> part. All msg_control should be dealt one by one as they do different
>> things. And it's not the fact that they ever require fs.
> 
> BTW, Jens mentioned that there is a queued patch that allows plain
> data msg_control. Are those not enough?

You mean the PROTO_CMSG_DATA_ONLY check?

It's not perfect, but better than nothing for a start.

But as far as I can see this is only in the recvmsg path, I'd need it
for sendmsg. Can this be fixed? It would also be great to have a way to
detect support for this from userspace.

It would also be great to somehow fill in .msg_iocb and handle
-EIOCBQUEUED from a socket and let a iocb->ki_complete() function to be called
in order to handle completions.

metze


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  reply	other threads:[~2020-11-18 16:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-07 13:20 [PATCH 5.11] io_uring: don't take fs for recvmsg/sendmsg Pavel Begunkov
2020-11-07 13:46 ` Stefan Metzmacher
2020-11-07 16:02   ` Pavel Begunkov
2020-11-07 16:07     ` Pavel Begunkov
2020-11-18 16:27       ` Stefan Metzmacher [this message]
2020-11-18 16:57         ` Stefan Metzmacher
2020-11-18 19:50           ` Pavel Begunkov
2020-11-19  9:17             ` Stefan Metzmacher
2020-11-15 13:07 ` Pavel Begunkov
2020-11-16 16:31 ` Jens Axboe

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