io_uring: Introduce IORING_OP_LISTEN

IORING_OP_LISTEN provides the semantic of listen(2) via io_uring.  While
this is an essentially synchronous system call, the main point is to
enable a network path to execute fully with io_uring registered and
descriptorless files.

Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/20240614163047.31581-4-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 28 insertions, 0 deletions

diff --git a/io_uring/net.c b/io_uring/net.c
index 8cc4cfc2fef3..db4a4a03ce3a 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -56,6 +56,11 @@ struct io_bind {
 	int				addr_len;
 };
 
+struct io_listen {
+	struct file			*file;
+	int				backlog;
+};
+
 struct io_sr_msg {
 	struct file			*file;
 	union {
@@ -1751,6 +1756,29 @@ int io_bind(struct io_kiocb *req, unsigned int issue_flags)
 	return 0;
 }
 
+int io_listen_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_listen *listen = io_kiocb_to_cmd(req, struct io_listen);
+
+	if (sqe->addr || sqe->buf_index || sqe->rw_flags || sqe->splice_fd_in || sqe->addr2)
+		return -EINVAL;
+
+	listen->backlog = READ_ONCE(sqe->len);
+	return 0;
+}
+
+int io_listen(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_listen *listen = io_kiocb_to_cmd(req, struct io_listen);
+	int ret;
+
+	ret = __sys_listen_socket(sock_from_file(req->file), listen->backlog);
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_set_res(req, ret, 0);
+	return 0;
+}
+
 void io_netmsg_cache_free(const void *entry)
 {
 	struct io_async_msghdr *kmsg = (struct io_async_msghdr *) entry;