Re: [RFC PATCH v3 3/3] io_uring: Add `sendto(2)` and `recvfrom(2)` support

[Praveen Kumar <kpraveen.lkml@gmail.com>]

On 30-12-2021 23:22, Ammar Faizi wrote:
> This adds sendto(2) and recvfrom(2) support for io_uring.
> 
> New opcodes:
>   IORING_OP_SENDTO
>   IORING_OP_RECVFROM
> 
> Cc: Nugra <richiisei@gmail.com>
> Tested-by: Nugra <richiisei@gmail.com>
> Link: https://github.com/axboe/liburing/issues/397
> Signed-off-by: Ammar Faizi <ammarfaizi2@gmail.com>
> ---
> 
> v3:
>   - Fix build error when CONFIG_NET is undefined should be done in
>     the first patch, not this patch.
> 
>   - Add Tested-by tag from Nugra.
> 
> v2:
>   - In `io_recvfrom()`, mark the error check of `move_addr_to_user()`
>     call as unlikely.
> 
>   - Fix build error when CONFIG_NET is undefined.
> 
>   - Added Nugra to CC list (tester).
> ---
>  fs/io_uring.c                 | 80 +++++++++++++++++++++++++++++++++--
>  include/uapi/linux/io_uring.h |  2 +
>  2 files changed, 78 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 7adcb591398f..3726958f8f58 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -575,7 +575,15 @@ struct io_sr_msg {
>  	union {
>  		struct compat_msghdr __user	*umsg_compat;
>  		struct user_msghdr __user	*umsg;
> -		void __user			*buf;
> +
> +		struct {
> +			void __user		*buf;
> +			struct sockaddr __user	*addr;
> +			union {
> +				int		sendto_addr_len;
> +				int __user	*recvfrom_addr_len;
> +			};
> +		};
>  	};
>  	int				msg_flags;
>  	int				bgid;
> @@ -1133,6 +1141,19 @@ static const struct io_op_def io_op_defs[] = {
>  		.needs_file = 1
>  	},
>  	[IORING_OP_GETXATTR] = {},
> +	[IORING_OP_SENDTO] = {
> +		.needs_file		= 1,
> +		.unbound_nonreg_file	= 1,
> +		.pollout		= 1,
> +		.audit_skip		= 1,
> +	},
> +	[IORING_OP_RECVFROM] = {
> +		.needs_file		= 1,
> +		.unbound_nonreg_file	= 1,
> +		.pollin			= 1,
> +		.buffer_select		= 1,
> +		.audit_skip		= 1,
> +	},
>  };
>  
>  /* requests with any of those set should undergo io_disarm_next() */
> @@ -5216,12 +5237,24 @@ static int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
>  		return -EINVAL;
>  
> +	/*
> +	 * For IORING_OP_SEND{,TO}, the assignment to @sr->umsg
> +	 * is equivalent to an assignment to @sr->buf.
> +	 */
>  	sr->umsg = u64_to_user_ptr(READ_ONCE(sqe->addr));
> +
>  	sr->len = READ_ONCE(sqe->len);
>  	sr->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL;
>  	if (sr->msg_flags & MSG_DONTWAIT)
>  		req->flags |= REQ_F_NOWAIT;
>  
> +	if (req->opcode == IORING_OP_SENDTO) {
> +		sr->addr = u64_to_user_ptr(READ_ONCE(sqe->addr2));
> +		sr->sendto_addr_len = READ_ONCE(sqe->addr3);
> +	} else {
> +		sr->addr = (struct sockaddr __user *) NULL;

Let's have sendto_addr_len  = 0  

> +	}
> +
>  #ifdef CONFIG_COMPAT
>  	if (req->ctx->compat)
>  		sr->msg_flags |= MSG_CMSG_COMPAT;
> @@ -5275,6 +5308,7 @@ static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
>  
>  static int io_sendto(struct io_kiocb *req, unsigned int issue_flags)
>  {
> +	struct sockaddr_storage address;
>  	struct io_sr_msg *sr = &req->sr_msg;
>  	struct msghdr msg;
>  	struct iovec iov;
> @@ -5291,10 +5325,20 @@ static int io_sendto(struct io_kiocb *req, unsigned int issue_flags)
>  	if (unlikely(ret))
>  		return ret;
>  
> -	msg.msg_name = NULL;
> +
>  	msg.msg_control = NULL;
>  	msg.msg_controllen = 0;
> -	msg.msg_namelen = 0;
> +	if (sr->addr) {
> +		ret = move_addr_to_kernel(sr->addr, sr->sendto_addr_len,
> +					  &address);
> +		if (unlikely(ret < 0))
> +			goto fail;
> +		msg.msg_name = (struct sockaddr *) &address;
> +		msg.msg_namelen = sr->sendto_addr_len;
> +	} else {
> +		msg.msg_name = NULL;
> +		msg.msg_namelen = 0;
> +	}
>  
>  	flags = req->sr_msg.msg_flags;
>  	if (issue_flags & IO_URING_F_NONBLOCK)
> @@ -5309,6 +5353,7 @@ static int io_sendto(struct io_kiocb *req, unsigned int issue_flags)
>  			return -EAGAIN;
>  		if (ret == -ERESTARTSYS)
>  			ret = -EINTR;
> +	fail:
>  		req_set_fail(req);

I think there is a problem with "fail" goto statement. Not getting full clarity on this change. With latest kernel, I see req_set_fail(req) inside if check, which I don't see here. Can you please resend the patch on latest kernel version. Thanks.

>  	}
>  	__io_req_complete(req, issue_flags, ret, 0);
> @@ -5427,13 +5472,25 @@ static int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
>  		return -EINVAL;
>  
> +	/*
> +	 * For IORING_OP_RECV{,FROM}, the assignment to @sr->umsg
> +	 * is equivalent to an assignment to @sr->buf.
> +	 */
>  	sr->umsg = u64_to_user_ptr(READ_ONCE(sqe->addr));
> +
>  	sr->len = READ_ONCE(sqe->len);
>  	sr->bgid = READ_ONCE(sqe->buf_group);
>  	sr->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL;
>  	if (sr->msg_flags & MSG_DONTWAIT)
>  		req->flags |= REQ_F_NOWAIT;
>  
> +	if (req->opcode == IORING_OP_RECVFROM) {
> +		sr->addr = u64_to_user_ptr(READ_ONCE(sqe->addr2));
> +		sr->recvfrom_addr_len = u64_to_user_ptr(READ_ONCE(sqe->addr3));
> +	} else {
> +		sr->addr = (struct sockaddr __user *) NULL;

I think recvfrom_addr_len should also be pointed to NULL, instead of garbage for this case.

> +	}
> +
>  #ifdef CONFIG_COMPAT
>  	if (req->ctx->compat)
>  		sr->msg_flags |= MSG_CMSG_COMPAT;
> @@ -5509,6 +5566,7 @@ static int io_recvfrom(struct io_kiocb *req, unsigned int issue_flags)
>  	struct iovec iov;
>  	unsigned flags;
>  	int ret, min_ret = 0;
> +	struct sockaddr_storage address;
>  	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
>  
>  	sock = sock_from_file(req->file);
> @@ -5526,7 +5584,7 @@ static int io_recvfrom(struct io_kiocb *req, unsigned int issue_flags)
>  	if (unlikely(ret))
>  		goto out_free;
>  
> -	msg.msg_name = NULL;
> +	msg.msg_name = sr->addr ? (struct sockaddr *) &address : NULL;
>  	msg.msg_control = NULL;
>  	msg.msg_controllen = 0;
>  	msg.msg_namelen = 0;

I think namelen should also be updated ?

> @@ -5540,6 +5598,16 @@ static int io_recvfrom(struct io_kiocb *req, unsigned int issue_flags)
>  		min_ret = iov_iter_count(&msg.msg_iter);
>  
>  	ret = sock_recvmsg(sock, &msg, flags);
> +
> +	if (ret >= 0 && sr->addr != NULL) {
> +		int tmp;
> +
> +		tmp = move_addr_to_user(&address, msg.msg_namelen, sr->addr,
> +					sr->recvfrom_addr_len);
> +		if (unlikely(tmp < 0))
> +			ret = tmp;
> +	}
> +
>  out_free:
>  	if (ret < min_ret) {
>  		if (ret == -EAGAIN && force_nonblock)
> @@ -6778,9 +6846,11 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>  	case IORING_OP_SYNC_FILE_RANGE:
>  		return io_sfr_prep(req, sqe);
>  	case IORING_OP_SENDMSG:
> +	case IORING_OP_SENDTO:
>  	case IORING_OP_SEND:
>  		return io_sendmsg_prep(req, sqe);
>  	case IORING_OP_RECVMSG:
> +	case IORING_OP_RECVFROM:
>  	case IORING_OP_RECV:
>  		return io_recvmsg_prep(req, sqe);
>  	case IORING_OP_CONNECT:
> @@ -7060,12 +7130,14 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
>  	case IORING_OP_SENDMSG:
>  		ret = io_sendmsg(req, issue_flags);
>  		break;
> +	case IORING_OP_SENDTO:
>  	case IORING_OP_SEND:
>  		ret = io_sendto(req, issue_flags);
>  		break;
>  	case IORING_OP_RECVMSG:
>  		ret = io_recvmsg(req, issue_flags);
>  		break;
> +	case IORING_OP_RECVFROM:
>  	case IORING_OP_RECV:
>  		ret = io_recvfrom(req, issue_flags);
>  		break;
> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
> index efc7ac9b3a6b..a360069d1e8e 100644
> --- a/include/uapi/linux/io_uring.h
> +++ b/include/uapi/linux/io_uring.h
> @@ -150,6 +150,8 @@ enum {
>  	IORING_OP_SETXATTR,
>  	IORING_OP_FGETXATTR,
>  	IORING_OP_GETXATTR,
> +	IORING_OP_SENDTO,
> +	IORING_OP_RECVFROM,
>  
>  	/* this goes last, obviously */
>  	IORING_OP_LAST,


Regards,

~Praveen.