1 files changed, 291 insertions, 0 deletions
diff --git a/net/handshake/netlink.c b/net/handshake/netlink.c
new file mode 100644
index 000000000..80c730269
--- /dev/null
+++ b/net/handshake/netlink.c
@@ -0,0 +1,291 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic netlink handshake service
+ *
+ * Author: Chuck Lever <chuck.lever@oracle.com>
+ *
+ * Copyright (c) 2023, Oracle and/or its affiliates.
+ */
+
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/mm.h>
+
+#include <net/sock.h>
+#include <net/genetlink.h>
+#include <net/netns/generic.h>
+
+#include <kunit/visibility.h>
+
+#include <uapi/linux/handshake.h>
+#include "handshake.h"
+#include "genl.h"
+
+#include <trace/events/handshake.h>
+
+/**
+ * handshake_genl_notify - Notify handlers that a request is waiting
+ * @net: target network namespace
+ * @proto: handshake protocol
+ * @flags: memory allocation control flags
+ *
+ * Returns zero on success or a negative errno if notification failed.
+ */
+int handshake_genl_notify(struct net *net, const struct handshake_proto *proto,
+			  gfp_t flags)
+{
+	struct sk_buff *msg;
+	void *hdr;
+
+	/* Disable notifications during unit testing */
+	if (!test_bit(HANDSHAKE_F_PROTO_NOTIFY, &proto->hp_flags))
+		return 0;
+
+	if (!genl_has_listeners(&handshake_nl_family, net,
+				proto->hp_handler_class))
+		return -ESRCH;
+
+	msg = genlmsg_new(GENLMSG_DEFAULT_SIZE, flags);
+	if (!msg)
+		return -ENOMEM;
+
+	hdr = genlmsg_put(msg, 0, 0, &handshake_nl_family, 0,
+			  HANDSHAKE_CMD_READY);
+	if (!hdr)
+		goto out_free;
+
+	if (nla_put_u32(msg, HANDSHAKE_A_ACCEPT_HANDLER_CLASS,
+			proto->hp_handler_class) < 0) {
+		genlmsg_cancel(msg, hdr);
+		goto out_free;
+	}
+
+	genlmsg_end(msg, hdr);
+	return genlmsg_multicast_netns(&handshake_nl_family, net, msg,
+				       0, proto->hp_handler_class, flags);
+
+out_free:
+	nlmsg_free(msg);
+	return -EMSGSIZE;
+}
+
+/**
+ * handshake_genl_put - Create a generic netlink message header
+ * @msg: buffer in which to create the header
+ * @info: generic netlink message context
+ *
+ * Returns a ready-to-use header, or NULL.
+ */
+struct nlmsghdr *handshake_genl_put(struct sk_buff *msg,
+				    struct genl_info *info)
+{
+	return genlmsg_put(msg, info->snd_portid, info->snd_seq,
+			   &handshake_nl_family, 0, info->genlhdr->cmd);
+}
+EXPORT_SYMBOL(handshake_genl_put);
+
+int handshake_nl_accept_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	struct net *net = sock_net(skb->sk);
+	struct handshake_net *hn = handshake_pernet(net);
+	struct handshake_req *req = NULL;
+	struct socket *sock;
+	int class, fd, err;
+
+	err = -EOPNOTSUPP;
+	if (!hn)
+		goto out_status;
+
+	err = -EINVAL;
+	if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_ACCEPT_HANDLER_CLASS))
+		goto out_status;
+	class = nla_get_u32(info->attrs[HANDSHAKE_A_ACCEPT_HANDLER_CLASS]);
+
+	err = -EAGAIN;
+	req = handshake_req_next(hn, class);
+	if (!req)
+		goto out_status;
+
+	sock = req->hr_sk->sk_socket;
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0) {
+		err = fd;
+		goto out_complete;
+	}
+
+	err = req->hr_proto->hp_accept(req, info, fd);
+	if (err) {
+		put_unused_fd(fd);
+		goto out_complete;
+	}
+
+	fd_install(fd, get_file(sock->file));
+
+	trace_handshake_cmd_accept(net, req, req->hr_sk, fd);
+	return 0;
+
+out_complete:
+	handshake_complete(req, -EIO, NULL);
+out_status:
+	trace_handshake_cmd_accept_err(net, req, NULL, err);
+	return err;
+}
+
+int handshake_nl_done_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	struct net *net = sock_net(skb->sk);
+	struct handshake_req *req;
+	struct socket *sock;
+	int fd, status, err;
+
+	if (GENL_REQ_ATTR_CHECK(info, HANDSHAKE_A_DONE_SOCKFD))
+		return -EINVAL;
+	fd = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_SOCKFD]);
+
+	sock = sockfd_lookup(fd, &err);
+	if (!sock)
+		return err;
+
+	req = handshake_req_hash_lookup(sock->sk);
+	if (!req) {
+		err = -EBUSY;
+		trace_handshake_cmd_done_err(net, req, sock->sk, err);
+		fput(sock->file);
+		return err;
+	}
+
+	trace_handshake_cmd_done(net, req, sock->sk, fd);
+
+	status = -EIO;
+	if (info->attrs[HANDSHAKE_A_DONE_STATUS])
+		status = nla_get_u32(info->attrs[HANDSHAKE_A_DONE_STATUS]);
+
+	handshake_complete(req, status, info);
+	fput(sock->file);
+	return 0;
+}
+
+static unsigned int handshake_net_id;
+
+static int __net_init handshake_net_init(struct net *net)
+{
+	struct handshake_net *hn = net_generic(net, handshake_net_id);
+	unsigned long tmp;
+	struct sysinfo si;
+
+	/*
+	 * Arbitrary limit to prevent handshakes that do not make
+	 * progress from clogging up the system. The cap scales up
+	 * with the amount of physical memory on the system.
+	 */
+	si_meminfo(&si);
+	tmp = si.totalram / (25 * si.mem_unit);
+	hn->hn_pending_max = clamp(tmp, 3UL, 50UL);
+
+	spin_lock_init(&hn->hn_lock);
+	hn->hn_pending = 0;
+	hn->hn_flags = 0;
+	INIT_LIST_HEAD(&hn->hn_requests);
+	return 0;
+}
+
+static void __net_exit handshake_net_exit(struct net *net)
+{
+	struct handshake_net *hn = net_generic(net, handshake_net_id);
+	struct handshake_req *req;
+	LIST_HEAD(requests);
+
+	/*
+	 * Drain the net's pending list. Requests that have been
+	 * accepted and are in progress will be destroyed when
+	 * the socket is closed.
+	 */
+	spin_lock(&hn->hn_lock);
+	set_bit(HANDSHAKE_F_NET_DRAINING, &hn->hn_flags);
+	list_splice_init(&requests, &hn->hn_requests);
+	spin_unlock(&hn->hn_lock);
+
+	while (!list_empty(&requests)) {
+		req = list_first_entry(&requests, struct handshake_req, hr_list);
+		list_del(&req->hr_list);
+
+		/*
+		 * Requests on this list have not yet been
+		 * accepted, so they do not have an fd to put.
+		 */
+
+		handshake_complete(req, -ETIMEDOUT, NULL);
+	}
+}
+
+static struct pernet_operations handshake_genl_net_ops = {
+	.init		= handshake_net_init,
+	.exit		= handshake_net_exit,
+	.id		= &handshake_net_id,
+	.size		= sizeof(struct handshake_net),
+};
+
+/**
+ * handshake_pernet - Get the handshake private per-net structure
+ * @net: network namespace
+ *
+ * Returns a pointer to the net's private per-net structure for the
+ * handshake module, or NULL if handshake_init() failed.
+ */
+struct handshake_net *handshake_pernet(struct net *net)
+{
+	return handshake_net_id ?
+		net_generic(net, handshake_net_id) : NULL;
+}
+EXPORT_SYMBOL_IF_KUNIT(handshake_pernet);
+
+static int __init handshake_init(void)
+{
+	int ret;
+
+	ret = handshake_req_hash_init();
+	if (ret) {
+		pr_warn("handshake: hash initialization failed (%d)\n", ret);
+		return ret;
+	}
+
+	ret = genl_register_family(&handshake_nl_family);
+	if (ret) {
+		pr_warn("handshake: netlink registration failed (%d)\n", ret);
+		handshake_req_hash_destroy();
+		return ret;
+	}
+
+	/*
+	 * ORDER: register_pernet_subsys must be done last.
+	 *
+	 *	If initialization does not make it past pernet_subsys
+	 *	registration, then handshake_net_id will remain 0. That
+	 *	shunts the handshake consumer API to return ENOTSUPP
+	 *	to prevent it from dereferencing something that hasn't
+	 *	been allocated.
+	 */
+	ret = register_pernet_subsys(&handshake_genl_net_ops);
+	if (ret) {
+		pr_warn("handshake: pernet registration failed (%d)\n", ret);
+		genl_unregister_family(&handshake_nl_family);
+		handshake_req_hash_destroy();
+	}
+
+	return ret;
+}
+
+static void __exit handshake_exit(void)
+{
+	unregister_pernet_subsys(&handshake_genl_net_ops);
+	handshake_net_id = 0;
+
+	handshake_req_hash_destroy();
+	genl_unregister_family(&handshake_nl_family);
+}
+
+module_init(handshake_init);
+module_exit(handshake_exit);