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

From: Ammar Faizi
Date: Thu Dec 30 2021 - 12:52:54 EST

This adds sendto(2) and recvfrom(2) support for io_uring.

New opcodes:
IORING_OP_SENDTO
IORING_OP_RECVFROM

Cc: Nugra <richiisei@xxxxxxxxx>
Tested-by: Nugra <richiisei@xxxxxxxxx>
Link: https://github.com/axboe/liburing/issues/397
Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxx>
---

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;
+ }
+
#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);
}
__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;
+ }
+
#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;
@@ -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,
--
2.32.0