[PATCH 2/3] io_uring/net: Drop custom iov copy in io_msg_copy_hdr

Similar to commit f4eaf8eda89e ("io_uring/rsrc: Drop io_copy_iov in
favor of iovec API"), avoid the custom copy of a single iovec and just
rely on the iovec api.  This lets the compat and native paths share the
buffer-select length lookup

Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
---
 io_uring/net.c | 69 ++++++++++++++------------------------------------
 1 file changed, 19 insertions(+), 50 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index a74d15f7b7d2..f476399e1d63 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -236,39 +236,6 @@ static int io_net_import_vec(struct io_kiocb *req, struct io_async_msghdr *iomsg
 	return 0;
 }
 
-static int io_compat_msg_copy_hdr(struct io_kiocb *req,
-				  struct io_async_msghdr *iomsg,
-				  struct compat_msghdr *msg, int ddir,
-				  struct sockaddr __user **save_addr)
-{
-	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct compat_iovec __user *uiov;
-	int ret;
-
-	if (copy_from_user(msg, sr->umsg_compat, sizeof(*msg)))
-		return -EFAULT;
-
-	ret = __get_compat_msghdr(&iomsg->msg, msg, save_addr);
-	if (ret)
-		return ret;
-
-	uiov = compat_ptr(msg->msg_iov);
-	if (req->flags & REQ_F_BUFFER_SELECT) {
-		if (msg->msg_iovlen == 0) {
-			sr->len = 0;
-		} else if (msg->msg_iovlen > 1) {
-			return -EINVAL;
-		} else {
-			struct compat_iovec tmp_iov;
-
-			if (copy_from_user(&tmp_iov, uiov, sizeof(tmp_iov)))
-				return -EFAULT;
-			sr->len = tmp_iov.iov_len;
-		}
-	}
-	return 0;
-}
-
 static int io_copy_msghdr_from_user(struct user_msghdr *msg,
 				    struct user_msghdr __user *umsg)
 {
@@ -292,7 +259,6 @@ static int io_msg_copy_hdr(struct io_kiocb *req, struct io_async_msghdr *iomsg,
 			   struct sockaddr __user **save_addr)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	struct user_msghdr __user *umsg = sr->umsg;
 	int ret;
 
 	iomsg->msg.msg_name = &iomsg->addr;
@@ -301,7 +267,10 @@ static int io_msg_copy_hdr(struct io_kiocb *req, struct io_async_msghdr *iomsg,
 	if (io_is_compat(req->ctx)) {
 		struct compat_msghdr cmsg;
 
-		ret = io_compat_msg_copy_hdr(req, iomsg, &cmsg, ddir, save_addr);
+		if (copy_from_user(&cmsg, sr->umsg_compat, sizeof(cmsg)))
+			return -EFAULT;
+
+		ret = __get_compat_msghdr(&iomsg->msg, &cmsg, save_addr);
 		if (ret)
 			return ret;
 
@@ -310,18 +279,17 @@ static int io_msg_copy_hdr(struct io_kiocb *req, struct io_async_msghdr *iomsg,
 		msg->msg_controllen = cmsg.msg_controllen;
 		msg->msg_iov = compat_ptr(cmsg.msg_iov);
 		msg->msg_iovlen = cmsg.msg_iovlen;
-		return 0;
-	}
-
-	ret = io_copy_msghdr_from_user(msg, umsg);
-	if (unlikely(ret))
-		return ret;
+	} else {
+		ret = io_copy_msghdr_from_user(msg, sr->umsg);
+		if (unlikely(ret))
+			return ret;
 
-	msg->msg_flags = 0;
+		msg->msg_flags = 0;
 
-	ret = __copy_msghdr(&iomsg->msg, msg, save_addr);
-	if (ret)
-		return ret;
+		ret = __copy_msghdr(&iomsg->msg, msg, save_addr);
+		if (ret)
+			return ret;
+	}
 
 	if (req->flags & REQ_F_BUFFER_SELECT) {
 		if (msg->msg_iovlen == 0) {
@@ -329,12 +297,13 @@ static int io_msg_copy_hdr(struct io_kiocb *req, struct io_async_msghdr *iomsg,
 		} else if (msg->msg_iovlen > 1) {
 			return -EINVAL;
 		} else {
-			struct iovec __user *uiov = msg->msg_iov;
-			struct iovec tmp_iov;
+			struct iovec fast_iov, *iov;
 
-			if (copy_from_user(&tmp_iov, uiov, sizeof(tmp_iov)))
-				return -EFAULT;
-			sr->len = tmp_iov.iov_len;
+			iov = iovec_from_user(msg->msg_iov, 1, 1, &fast_iov,
+					      io_is_compat(req->ctx));
+			if (IS_ERR(iov))
+				return PTR_ERR(iov);
+			sr->len = iov->iov_len;
 		}
 	}
 	return 0;
-- 
2.55.0