[PATCH for-next 08/12] io_uring: recv/recvmsg retarget_rsrc support

[Dylan Yudaken <dylany@meta.com>]

Add can_retarget_rsrc handler for recv/recvmsg

Signed-off-by: Dylan Yudaken <dylany@meta.com>
---
 io_uring/net.c   | 22 +++++++++++++++++++++-
 io_uring/net.h   |  1 +
 io_uring/opdef.c |  2 ++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index f4638e79a022..0fa05ef52dd3 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -70,6 +70,11 @@ struct io_send_zc_msg {
 	struct io_kiocb		*notif;
 };
 
+struct io_recv_msg {
+	struct io_sr_msg	sr;
+	int			retarget_fd;
+};
+
 
 #define IO_APOLL_MULTI_POLLED (REQ_F_APOLL_MULTISHOT | REQ_F_POLLED)
 
@@ -547,7 +552,8 @@ int io_recvmsg_prep_async(struct io_kiocb *req)
 
 int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
-	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
+	struct io_recv_msg *rcv = io_kiocb_to_cmd(req, struct io_recv_msg);
+	struct io_sr_msg *sr = &rcv->sr;
 
 	if (unlikely(sqe->file_index || sqe->addr2))
 		return -EINVAL;
@@ -572,6 +578,11 @@ int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		req->flags |= REQ_F_APOLL_MULTISHOT;
 	}
 
+	if (req->flags & REQ_F_FIXED_FILE)
+		rcv->retarget_fd = req->cqe.fd;
+	else
+		rcv->retarget_fd = -1;
+
 #ifdef CONFIG_COMPAT
 	if (req->ctx->compat)
 		sr->msg_flags |= MSG_CMSG_COMPAT;
@@ -709,6 +720,15 @@ static int io_recvmsg_multishot(struct socket *sock, struct io_sr_msg *io,
 			kmsg->controllen + err;
 }
 
+bool io_recv_can_retarget_rsrc(struct io_kiocb *req)
+{
+	struct io_recv_msg *rcv = io_kiocb_to_cmd(req, struct io_recv_msg);
+
+	if (rcv->retarget_fd < 0)
+		return false;
+	return io_file_peek_fixed(req, rcv->retarget_fd) == req->file;
+}
+
 int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
diff --git a/io_uring/net.h b/io_uring/net.h
index 5ffa11bf5d2e..6b5719084494 100644
--- a/io_uring/net.h
+++ b/io_uring/net.h
@@ -43,6 +43,7 @@ int io_recvmsg_prep_async(struct io_kiocb *req);
 int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
 int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags);
 int io_recv(struct io_kiocb *req, unsigned int issue_flags);
+bool io_recv_can_retarget_rsrc(struct io_kiocb *req);
 
 void io_sendrecv_fail(struct io_kiocb *req);
 
diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index 83dc0f9ad3b2..1a0be5681c7b 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -178,6 +178,7 @@ const struct io_op_def io_op_defs[] = {
 		.prep_async		= io_recvmsg_prep_async,
 		.cleanup		= io_sendmsg_recvmsg_cleanup,
 		.fail			= io_sendrecv_fail,
+		.can_retarget_rsrc	= io_recv_can_retarget_rsrc,
 #else
 		.prep			= io_eopnotsupp_prep,
 #endif
@@ -340,6 +341,7 @@ const struct io_op_def io_op_defs[] = {
 		.prep			= io_recvmsg_prep,
 		.issue			= io_recv,
 		.fail			= io_sendrecv_fail,
+		.can_retarget_rsrc	= io_recv_can_retarget_rsrc,
 #else
 		.prep			= io_eopnotsupp_prep,
 #endif
-- 
2.30.2