Re: [PATCH v5 10/10] io_uring: add support for IORING_OP_MKNODAT

[Pavel Begunkov <asml.silence@gmail.com>]

On 6/3/21 6:18 AM, Dmitry Kadashev wrote:
> IORING_OP_MKNODAT behaves like mknodat(2) and takes the same flags and
> arguments.
> 
> Suggested-by: Christian Brauner <christian.brauner@ubuntu.com>
> Link: https://lore.kernel.org/io-uring/20210514145259.wtl4xcsp52woi6ab@wittgenstein/
> Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
> ---
>  fs/internal.h                 |  2 ++
>  fs/io_uring.c                 | 56 +++++++++++++++++++++++++++++++++++
>  fs/namei.c                    |  2 +-
>  include/uapi/linux/io_uring.h |  2 ++
>  4 files changed, 61 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/internal.h b/fs/internal.h
> index 15a7d210cc67..c6fb9974006f 100644

[...]

>  static bool io_disarm_next(struct io_kiocb *req);
> @@ -3687,6 +3697,44 @@ static int io_linkat(struct io_kiocb *req, int issue_flags)
>  	io_req_complete(req, ret);
>  	return 0;
>  }
> +static int io_mknodat_prep(struct io_kiocb *req,
> +			    const struct io_uring_sqe *sqe)
> +{
> +	struct io_mknod *mkn = &req->mknod;
> +	const char __user *fname;
> +
> +	if (unlikely(req->flags & REQ_F_FIXED_FILE))
> +		return -EBADF;

IOPOLL won't support it, and the check is missing.
Probably for other opcodes as well.

if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
	return -EINVAL;

> +
> +	mkn->dfd = READ_ONCE(sqe->fd);
> +	mkn->mode = READ_ONCE(sqe->len);
> +	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
> +	mkn->dev = READ_ONCE(sqe->mknod_dev);
> +
> +	mkn->filename = getname(fname);
> +	if (IS_ERR(mkn->filename))
> +		return PTR_ERR(mkn->filename);
> +
> +	req->flags |= REQ_F_NEED_CLEANUP;
> +	return 0;
> +}

-- 
Pavel Begunkov