Re: io_uring and crypto

[Jens Axboe <axboe@kernel.dk>]

On 10/7/25 11:11 AM, David Howells wrote:
> Hi Jens,
> 
> I was wondering if it might be possible to adapt io_uring to make
> crypto requests as io_uring primitives rather than just having
> io_uring call sendmsg and recvmsg on an AF_ALG socket.
> 
> The reason I think this might make sense is that for the certain
> crypto ops we need to pass two buffers, one input and one output
> (encrypt, decrypt, sign) or two input (verify) and this could directly
> translate to an async crypto request.
> 
> Or possibly we should have a sendrecv socket call (RPC sort of thing)
> and have io_uring drive that.

You could certainly wire it up via io_uring in either way. I don't know
the crypto API, but ideally you need something where you the issue and
completions ide split, rather than just a boring sync syscall type
thing. For the latter, io_uring can't really help you outside of punting
to a thread. Having a reliable way to do non-blocking issue and then
poll for readiness if non-blocking failed would suffice, ideally you
want a way to issue/start the operation and get a callback when it
completes.

> The tricky bit is that it would require two buffers and io_uring seems
> geared around one.

io_uring doesn't care, it's just a transport in that sense. You can
define what the SQE looks like entirely for your opcode, and have 3
buffers per operation if you like.

-- 
Jens Axboe