net/handshake/netlink.c - linux - Git at Google

 // 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);

 /*
  * dup() a kernel socket for use as a user space file descriptor
  * in the current process. The kernel socket must have an
  * instatiated struct file.
  *
  * Implicit argument: "current()"
  */
 static int handshake_dup(struct socket *sock)
 {
 	struct file *file;
 	int newfd;

 	file = get_file(sock->file);
 	newfd = get_unused_fd_flags(O_CLOEXEC);
 	if (newfd < 0) {
 		fput(file);
 		return newfd;
 	}

 	fd_install(newfd, file);
 	return newfd;
 }

 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 = handshake_dup(sock);
 	if (fd < 0) {
 		err = fd;
 		goto out_complete;
 	}
 	err = req->hr_proto->hp_accept(req, info, fd);
 	if (err) {
 		fput(sock->file);
 		goto out_complete;
 	}

 	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 = NULL;
 	struct socket *sock = NULL;
 	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]);

 	err = 0;
 	sock = sockfd_lookup(fd, &err);
 	if (err) {
 		err = -EBADF;
 		goto out_status;
 	}

 	req = handshake_req_hash_lookup(sock->sk);
 	if (!req) {
 		err = -EBUSY;
 		fput(sock->file);
 		goto out_status;
 	}

 	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;

 out_status:
 	trace_handshake_cmd_done_err(net, req, sock->sk, err);
 	return err;
 }

 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);
	// 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);

	/*
	* dup() a kernel socket for use as a user space file descriptor
	* in the current process. The kernel socket must have an
	* instatiated struct file.
	*
	* Implicit argument: "current()"
	*/
	static int handshake_dup(struct socket *sock)
	{
	struct file *file;
	int newfd;

	file = get_file(sock->file);
	newfd = get_unused_fd_flags(O_CLOEXEC);
	if (newfd < 0) {
	fput(file);
	return newfd;
	}

	fd_install(newfd, file);
	return newfd;
	}

	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 = handshake_dup(sock);
	if (fd < 0) {
	err = fd;
	goto out_complete;
	}
	err = req->hr_proto->hp_accept(req, info, fd);
	if (err) {
	fput(sock->file);
	goto out_complete;
	}

	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 = NULL;
	struct socket *sock = NULL;
	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]);

	err = 0;
	sock = sockfd_lookup(fd, &err);
	if (err) {
	err = -EBADF;
	goto out_status;
	}

	req = handshake_req_hash_lookup(sock->sk);
	if (!req) {
	err = -EBUSY;
	fput(sock->file);
	goto out_status;
	}

	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;

	out_status:
	trace_handshake_cmd_done_err(net, req, sock->sk, err);
	return err;
	}

	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);