net/mctp/device.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Management Component Transport Protocol (MCTP) - device implementation.
  *
  * Copyright (c) 2021 Code Construct
  * Copyright (c) 2021 Google
  */

 #include <linux/if_arp.h>
 #include <linux/if_link.h>
 #include <linux/mctp.h>
 #include <linux/netdevice.h>
 #include <linux/rcupdate.h>
 #include <linux/rtnetlink.h>

 #include <net/addrconf.h>
 #include <net/netlink.h>
 #include <net/mctp.h>
 #include <net/mctpdevice.h>
 #include <net/sock.h>

 struct mctp_dump_cb {
 	int h;
 	int idx;
 	size_t a_idx;
 };

 /* unlocked: caller must hold rcu_read_lock.
  * Returned mctp_dev has its refcount incremented, or NULL if unset.
  */
 struct mctp_dev *__mctp_dev_get(const struct net_device *dev)
 {
 	struct mctp_dev *mdev = rcu_dereference(dev->mctp_ptr);

 	/* RCU guarantees that any mdev is still live.
 	 * Zero refcount implies a pending free, return NULL.
 	 */
 	if (mdev)
 		if (!refcount_inc_not_zero(&mdev->refs))
 			return NULL;
 	return mdev;
 }

 /* Returned mctp_dev does not have refcount incremented. The returned pointer
  * remains live while rtnl_lock is held, as that prevents mctp_unregister()
  */
 struct mctp_dev *mctp_dev_get_rtnl(const struct net_device *dev)
 {
 	return rtnl_dereference(dev->mctp_ptr);
 }

 static int mctp_addrinfo_size(void)
 {
 	return NLMSG_ALIGN(sizeof(struct ifaddrmsg))
 		+ nla_total_size(1) // IFA_LOCAL
 		+ nla_total_size(1) // IFA_ADDRESS
 		;
 }

 /* flag should be NLM_F_MULTI for dump calls */
 static int mctp_fill_addrinfo(struct sk_buff *skb,
 			      struct mctp_dev *mdev, mctp_eid_t eid,
 			      int msg_type, u32 portid, u32 seq, int flag)
 {
 	struct ifaddrmsg *hdr;
 	struct nlmsghdr *nlh;

 	nlh = nlmsg_put(skb, portid, seq,
 			msg_type, sizeof(*hdr), flag);
 	if (!nlh)
 		return -EMSGSIZE;

 	hdr = nlmsg_data(nlh);
 	hdr->ifa_family = AF_MCTP;
 	hdr->ifa_prefixlen = 0;
 	hdr->ifa_flags = 0;
 	hdr->ifa_scope = 0;
 	hdr->ifa_index = mdev->dev->ifindex;

 	if (nla_put_u8(skb, IFA_LOCAL, eid))
 		goto cancel;

 	if (nla_put_u8(skb, IFA_ADDRESS, eid))
 		goto cancel;

 	nlmsg_end(skb, nlh);

 	return 0;

 cancel:
 	nlmsg_cancel(skb, nlh);
 	return -EMSGSIZE;
 }

 static int mctp_dump_dev_addrinfo(struct mctp_dev *mdev, struct sk_buff *skb,
 				  struct netlink_callback *cb)
 {
 	struct mctp_dump_cb *mcb = (void *)cb->ctx;
 	u32 portid, seq;
 	int rc = 0;

 	portid = NETLINK_CB(cb->skb).portid;
 	seq = cb->nlh->nlmsg_seq;
 	for (; mcb->a_idx < mdev->num_addrs; mcb->a_idx++) {
 		rc = mctp_fill_addrinfo(skb, mdev, mdev->addrs[mcb->a_idx],
 					RTM_NEWADDR, portid, seq, NLM_F_MULTI);
 		if (rc < 0)
 			break;
 	}

 	return rc;
 }

 static int mctp_dump_addrinfo(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct mctp_dump_cb *mcb = (void *)cb->ctx;
 	struct net *net = sock_net(skb->sk);
 	struct hlist_head *head;
 	struct net_device *dev;
 	struct ifaddrmsg *hdr;
 	struct mctp_dev *mdev;
 	int ifindex;
 	int idx = 0, rc;

 	hdr = nlmsg_data(cb->nlh);
 	// filter by ifindex if requested
 	ifindex = hdr->ifa_index;

 	rcu_read_lock();
 	for (; mcb->h < NETDEV_HASHENTRIES; mcb->h++, mcb->idx = 0) {
 		idx = 0;
 		head = &net->dev_index_head[mcb->h];
 		hlist_for_each_entry_rcu(dev, head, index_hlist) {
 			if (idx >= mcb->idx &&
 			    (ifindex == 0 || ifindex == dev->ifindex)) {
 				mdev = __mctp_dev_get(dev);
 				if (mdev) {
 					rc = mctp_dump_dev_addrinfo(mdev,
 								    skb, cb);
 					mctp_dev_put(mdev);
 					// Error indicates full buffer, this
 					// callback will get retried.
 					if (rc < 0)
 						goto out;
 				}
 			}
 			idx++;
 			// reset for next iteration
 			mcb->a_idx = 0;
 		}
 	}
 out:
 	rcu_read_unlock();
 	mcb->idx = idx;

 	return skb->len;
 }

 static void mctp_addr_notify(struct mctp_dev *mdev, mctp_eid_t eid, int msg_type,
 			     struct sk_buff *req_skb, struct nlmsghdr *req_nlh)
 {
 	u32 portid = NETLINK_CB(req_skb).portid;
 	struct net *net = dev_net(mdev->dev);
 	struct sk_buff *skb;
 	int rc = -ENOBUFS;

 	skb = nlmsg_new(mctp_addrinfo_size(), GFP_KERNEL);
 	if (!skb)
 		goto out;

 	rc = mctp_fill_addrinfo(skb, mdev, eid, msg_type,
 				portid, req_nlh->nlmsg_seq, 0);
 	if (rc < 0) {
 		WARN_ON_ONCE(rc == -EMSGSIZE);
 		goto out;
 	}

 	rtnl_notify(skb, net, portid, RTNLGRP_MCTP_IFADDR, req_nlh, GFP_KERNEL);
 	return;
 out:
 	kfree_skb(skb);
 	rtnl_set_sk_err(net, RTNLGRP_MCTP_IFADDR, rc);
 }

 static const struct nla_policy ifa_mctp_policy[IFA_MAX + 1] = {
 	[IFA_ADDRESS]		= { .type = NLA_U8 },
 	[IFA_LOCAL]		= { .type = NLA_U8 },
 };

 static int mctp_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh,
 			    struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
 	struct nlattr *tb[IFA_MAX + 1];
 	struct net_device *dev;
 	struct mctp_addr *addr;
 	struct mctp_dev *mdev;
 	struct ifaddrmsg *ifm;
 	unsigned long flags;
 	u8 *tmp_addrs;
 	int rc;

 	rc = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_mctp_policy,
 			 extack);
 	if (rc < 0)
 		return rc;

 	ifm = nlmsg_data(nlh);

 	if (tb[IFA_LOCAL])
 		addr = nla_data(tb[IFA_LOCAL]);
 	else if (tb[IFA_ADDRESS])
 		addr = nla_data(tb[IFA_ADDRESS]);
 	else
 		return -EINVAL;

 	/* find device */
 	dev = __dev_get_by_index(net, ifm->ifa_index);
 	if (!dev)
 		return -ENODEV;

 	mdev = mctp_dev_get_rtnl(dev);
 	if (!mdev)
 		return -ENODEV;

 	if (!mctp_address_unicast(addr->s_addr))
 		return -EINVAL;

 	/* Prevent duplicates. Under RTNL so don't need to lock for reading */
 	if (memchr(mdev->addrs, addr->s_addr, mdev->num_addrs))
 		return -EEXIST;

 	tmp_addrs = kmalloc(mdev->num_addrs + 1, GFP_KERNEL);
 	if (!tmp_addrs)
 		return -ENOMEM;
 	memcpy(tmp_addrs, mdev->addrs, mdev->num_addrs);
 	tmp_addrs[mdev->num_addrs] = addr->s_addr;

 	/* Lock to write */
 	spin_lock_irqsave(&mdev->addrs_lock, flags);
 	mdev->num_addrs++;
 	swap(mdev->addrs, tmp_addrs);
 	spin_unlock_irqrestore(&mdev->addrs_lock, flags);

 	kfree(tmp_addrs);

 	mctp_addr_notify(mdev, addr->s_addr, RTM_NEWADDR, skb, nlh);
 	mctp_route_add_local(mdev, addr->s_addr);

 	return 0;
 }

 static int mctp_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
 			    struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
 	struct nlattr *tb[IFA_MAX + 1];
 	struct net_device *dev;
 	struct mctp_addr *addr;
 	struct mctp_dev *mdev;
 	struct ifaddrmsg *ifm;
 	unsigned long flags;
 	u8 *pos;
 	int rc;

 	rc = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_mctp_policy,
 			 extack);
 	if (rc < 0)
 		return rc;

 	ifm = nlmsg_data(nlh);

 	if (tb[IFA_LOCAL])
 		addr = nla_data(tb[IFA_LOCAL]);
 	else if (tb[IFA_ADDRESS])
 		addr = nla_data(tb[IFA_ADDRESS]);
 	else
 		return -EINVAL;

 	/* find device */
 	dev = __dev_get_by_index(net, ifm->ifa_index);
 	if (!dev)
 		return -ENODEV;

 	mdev = mctp_dev_get_rtnl(dev);
 	if (!mdev)
 		return -ENODEV;

 	pos = memchr(mdev->addrs, addr->s_addr, mdev->num_addrs);
 	if (!pos)
 		return -ENOENT;

 	rc = mctp_route_remove_local(mdev, addr->s_addr);
 	// we can ignore -ENOENT in the case a route was already removed
 	if (rc < 0 && rc != -ENOENT)
 		return rc;

 	spin_lock_irqsave(&mdev->addrs_lock, flags);
 	memmove(pos, pos + 1, mdev->num_addrs - 1 - (pos - mdev->addrs));
 	mdev->num_addrs--;
 	spin_unlock_irqrestore(&mdev->addrs_lock, flags);

 	mctp_addr_notify(mdev, addr->s_addr, RTM_DELADDR, skb, nlh);

 	return 0;
 }

 void mctp_dev_hold(struct mctp_dev *mdev)
 {
 	refcount_inc(&mdev->refs);
 }

 void mctp_dev_put(struct mctp_dev *mdev)
 {
 	if (mdev && refcount_dec_and_test(&mdev->refs)) {
 		kfree(mdev->addrs);
 		dev_put(mdev->dev);
 		kfree_rcu(mdev, rcu);
 	}
 }

 void mctp_dev_release_key(struct mctp_dev *dev, struct mctp_sk_key *key)
 	__must_hold(&key->lock)
 {
 	if (!dev)
 		return;
 	if (dev->ops && dev->ops->release_flow)
 		dev->ops->release_flow(dev, key);
 	key->dev = NULL;
 	mctp_dev_put(dev);
 }

 void mctp_dev_set_key(struct mctp_dev *dev, struct mctp_sk_key *key)
 	__must_hold(&key->lock)
 {
 	mctp_dev_hold(dev);
 	key->dev = dev;
 }

 static struct mctp_dev *mctp_add_dev(struct net_device *dev)
 {
 	struct mctp_dev *mdev;

 	ASSERT_RTNL();

 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
 	if (!mdev)
 		return ERR_PTR(-ENOMEM);

 	spin_lock_init(&mdev->addrs_lock);

 	mdev->net = mctp_default_net(dev_net(dev));

 	/* associate to net_device */
 	refcount_set(&mdev->refs, 1);
 	rcu_assign_pointer(dev->mctp_ptr, mdev);

 	dev_hold(dev);
 	mdev->dev = dev;

 	return mdev;
 }

 static int mctp_fill_link_af(struct sk_buff *skb,
 			     const struct net_device *dev, u32 ext_filter_mask)
 {
 	struct mctp_dev *mdev;

 	mdev = mctp_dev_get_rtnl(dev);
 	if (!mdev)
 		return -ENODATA;
 	if (nla_put_u32(skb, IFLA_MCTP_NET, mdev->net))
 		return -EMSGSIZE;
 	return 0;
 }

 static size_t mctp_get_link_af_size(const struct net_device *dev,
 				    u32 ext_filter_mask)
 {
 	struct mctp_dev *mdev;
 	unsigned int ret;

 	/* caller holds RCU */
 	mdev = __mctp_dev_get(dev);
 	if (!mdev)
 		return 0;
 	ret = nla_total_size(4); /* IFLA_MCTP_NET */
 	mctp_dev_put(mdev);
 	return ret;
 }

 static const struct nla_policy ifla_af_mctp_policy[IFLA_MCTP_MAX + 1] = {
 	[IFLA_MCTP_NET]		= { .type = NLA_U32 },
 };

 static int mctp_set_link_af(struct net_device *dev, const struct nlattr *attr,
 			    struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[IFLA_MCTP_MAX + 1];
 	struct mctp_dev *mdev;
 	int rc;

 	rc = nla_parse_nested(tb, IFLA_MCTP_MAX, attr, ifla_af_mctp_policy,
 			      NULL);
 	if (rc)
 		return rc;

 	mdev = mctp_dev_get_rtnl(dev);
 	if (!mdev)
 		return 0;

 	if (tb[IFLA_MCTP_NET])
 		WRITE_ONCE(mdev->net, nla_get_u32(tb[IFLA_MCTP_NET]));

 	return 0;
 }

 /* Matches netdev types that should have MCTP handling */
 static bool mctp_known(struct net_device *dev)
 {
 	/* only register specific types (inc. NONE for TUN devices) */
 	return dev->type == ARPHRD_MCTP ||
 		   dev->type == ARPHRD_LOOPBACK ||
 		   dev->type == ARPHRD_NONE;
 }

 static void mctp_unregister(struct net_device *dev)
 {
 	struct mctp_dev *mdev;

 	mdev = mctp_dev_get_rtnl(dev);
 	if (!mdev)
 		return;

 	RCU_INIT_POINTER(mdev->dev->mctp_ptr, NULL);

 	mctp_route_remove_dev(mdev);
 	mctp_neigh_remove_dev(mdev);

 	mctp_dev_put(mdev);
 }

 static int mctp_register(struct net_device *dev)
 {
 	struct mctp_dev *mdev;

 	/* Already registered? */
 	if (rtnl_dereference(dev->mctp_ptr))
 		return 0;

 	/* only register specific types */
 	if (!mctp_known(dev))
 		return 0;

 	mdev = mctp_add_dev(dev);
 	if (IS_ERR(mdev))
 		return PTR_ERR(mdev);

 	return 0;
 }

 static int mctp_dev_notify(struct notifier_block *this, unsigned long event,
 			   void *ptr)
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	int rc;

 	switch (event) {
 	case NETDEV_REGISTER:
 		rc = mctp_register(dev);
 		if (rc)
 			return notifier_from_errno(rc);
 		break;
 	case NETDEV_UNREGISTER:
 		mctp_unregister(dev);
 		break;
 	}

 	return NOTIFY_OK;
 }

 static int mctp_register_netdevice(struct net_device *dev,
 				   const struct mctp_netdev_ops *ops)
 {
 	struct mctp_dev *mdev;

 	mdev = mctp_add_dev(dev);
 	if (IS_ERR(mdev))
 		return PTR_ERR(mdev);

 	mdev->ops = ops;

 	return register_netdevice(dev);
 }

 int mctp_register_netdev(struct net_device *dev,
 			 const struct mctp_netdev_ops *ops)
 {
 	int rc;

 	rtnl_lock();
 	rc = mctp_register_netdevice(dev, ops);
 	rtnl_unlock();

 	return rc;
 }
 EXPORT_SYMBOL_GPL(mctp_register_netdev);

 void mctp_unregister_netdev(struct net_device *dev)
 {
 	unregister_netdev(dev);
 }
 EXPORT_SYMBOL_GPL(mctp_unregister_netdev);

 static struct rtnl_af_ops mctp_af_ops = {
 	.family = AF_MCTP,
 	.fill_link_af = mctp_fill_link_af,
 	.get_link_af_size = mctp_get_link_af_size,
 	.set_link_af = mctp_set_link_af,
 };

 static struct notifier_block mctp_dev_nb = {
 	.notifier_call = mctp_dev_notify,
 	.priority = ADDRCONF_NOTIFY_PRIORITY,
 };

 static const struct rtnl_msg_handler mctp_device_rtnl_msg_handlers[] = {
 	{THIS_MODULE, PF_MCTP, RTM_NEWADDR, mctp_rtm_newaddr, NULL, 0},
 	{THIS_MODULE, PF_MCTP, RTM_DELADDR, mctp_rtm_deladdr, NULL, 0},
 	{THIS_MODULE, PF_MCTP, RTM_GETADDR, NULL, mctp_dump_addrinfo, 0},
 };

 int __init mctp_device_init(void)
 {
 	int err;

 	register_netdevice_notifier(&mctp_dev_nb);
 	rtnl_af_register(&mctp_af_ops);

 	err = rtnl_register_many(mctp_device_rtnl_msg_handlers);
 	if (err) {
 		rtnl_af_unregister(&mctp_af_ops);
 		unregister_netdevice_notifier(&mctp_dev_nb);
 	}

 	return err;
 }

 void __exit mctp_device_exit(void)
 {
 	rtnl_unregister_many(mctp_device_rtnl_msg_handlers);
 	rtnl_af_unregister(&mctp_af_ops);
 	unregister_netdevice_notifier(&mctp_dev_nb);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Management Component Transport Protocol (MCTP) - device implementation.
	*
	* Copyright (c) 2021 Code Construct
	* Copyright (c) 2021 Google
	*/

	#include <linux/if_arp.h>
	#include <linux/if_link.h>
	#include <linux/mctp.h>
	#include <linux/netdevice.h>
	#include <linux/rcupdate.h>
	#include <linux/rtnetlink.h>

	#include <net/addrconf.h>
	#include <net/netlink.h>
	#include <net/mctp.h>
	#include <net/mctpdevice.h>
	#include <net/sock.h>

	struct mctp_dump_cb {
	int h;
	int idx;
	size_t a_idx;
	};

	/* unlocked: caller must hold rcu_read_lock.
	* Returned mctp_dev has its refcount incremented, or NULL if unset.
	*/
	struct mctp_dev __mctp_dev_get(const struct net_device dev)
	{
	struct mctp_dev *mdev = rcu_dereference(dev->mctp_ptr);

	/* RCU guarantees that any mdev is still live.
	* Zero refcount implies a pending free, return NULL.
	*/
	if (mdev)
	if (!refcount_inc_not_zero(&mdev->refs))
	return NULL;
	return mdev;
	}

	/* Returned mctp_dev does not have refcount incremented. The returned pointer
	* remains live while rtnl_lock is held, as that prevents mctp_unregister()
	*/
	struct mctp_dev mctp_dev_get_rtnl(const struct net_device dev)
	{
	return rtnl_dereference(dev->mctp_ptr);
	}

	static int mctp_addrinfo_size(void)
	{
	return NLMSG_ALIGN(sizeof(struct ifaddrmsg))
	+ nla_total_size(1) // IFA_LOCAL
	+ nla_total_size(1) // IFA_ADDRESS
	;
	}

	/* flag should be NLM_F_MULTI for dump calls */
	static int mctp_fill_addrinfo(struct sk_buff *skb,
	struct mctp_dev *mdev, mctp_eid_t eid,
	int msg_type, u32 portid, u32 seq, int flag)
	{
	struct ifaddrmsg *hdr;
	struct nlmsghdr *nlh;

	nlh = nlmsg_put(skb, portid, seq,
	msg_type, sizeof(*hdr), flag);
	if (!nlh)
	return -EMSGSIZE;

	hdr = nlmsg_data(nlh);
	hdr->ifa_family = AF_MCTP;
	hdr->ifa_prefixlen = 0;
	hdr->ifa_flags = 0;
	hdr->ifa_scope = 0;
	hdr->ifa_index = mdev->dev->ifindex;

	if (nla_put_u8(skb, IFA_LOCAL, eid))
	goto cancel;

	if (nla_put_u8(skb, IFA_ADDRESS, eid))
	goto cancel;

	nlmsg_end(skb, nlh);

	return 0;

	cancel:
	nlmsg_cancel(skb, nlh);
	return -EMSGSIZE;
	}

	static int mctp_dump_dev_addrinfo(struct mctp_dev mdev, struct sk_buff skb,
	struct netlink_callback *cb)
	{
	struct mctp_dump_cb mcb = (void )cb->ctx;
	u32 portid, seq;
	int rc = 0;

	portid = NETLINK_CB(cb->skb).portid;
	seq = cb->nlh->nlmsg_seq;
	for (; mcb->a_idx < mdev->num_addrs; mcb->a_idx++) {
	rc = mctp_fill_addrinfo(skb, mdev, mdev->addrs[mcb->a_idx],
	RTM_NEWADDR, portid, seq, NLM_F_MULTI);
	if (rc < 0)
	break;
	}

	return rc;
	}

	static int mctp_dump_addrinfo(struct sk_buff skb, struct netlink_callback cb)
	{
	struct mctp_dump_cb mcb = (void )cb->ctx;
	struct net *net = sock_net(skb->sk);
	struct hlist_head *head;
	struct net_device *dev;
	struct ifaddrmsg *hdr;
	struct mctp_dev *mdev;
	int ifindex;
	int idx = 0, rc;

	hdr = nlmsg_data(cb->nlh);
	// filter by ifindex if requested
	ifindex = hdr->ifa_index;

	rcu_read_lock();
	for (; mcb->h < NETDEV_HASHENTRIES; mcb->h++, mcb->idx = 0) {
	idx = 0;
	head = &net->dev_index_head[mcb->h];
	hlist_for_each_entry_rcu(dev, head, index_hlist) {
	if (idx >= mcb->idx &&
	(ifindex == 0 \|\| ifindex == dev->ifindex)) {
	mdev = __mctp_dev_get(dev);
	if (mdev) {
	rc = mctp_dump_dev_addrinfo(mdev,
	skb, cb);
	mctp_dev_put(mdev);
	// Error indicates full buffer, this
	// callback will get retried.
	if (rc < 0)
	goto out;
	}
	}
	idx++;
	// reset for next iteration
	mcb->a_idx = 0;
	}
	}
	out:
	rcu_read_unlock();
	mcb->idx = idx;

	return skb->len;
	}

	static void mctp_addr_notify(struct mctp_dev *mdev, mctp_eid_t eid, int msg_type,
	struct sk_buff req_skb, struct nlmsghdr req_nlh)
	{
	u32 portid = NETLINK_CB(req_skb).portid;
	struct net *net = dev_net(mdev->dev);
	struct sk_buff *skb;
	int rc = -ENOBUFS;

	skb = nlmsg_new(mctp_addrinfo_size(), GFP_KERNEL);
	if (!skb)
	goto out;

	rc = mctp_fill_addrinfo(skb, mdev, eid, msg_type,
	portid, req_nlh->nlmsg_seq, 0);
	if (rc < 0) {
	WARN_ON_ONCE(rc == -EMSGSIZE);
	goto out;
	}

	rtnl_notify(skb, net, portid, RTNLGRP_MCTP_IFADDR, req_nlh, GFP_KERNEL);
	return;
	out:
	kfree_skb(skb);
	rtnl_set_sk_err(net, RTNLGRP_MCTP_IFADDR, rc);
	}

	static const struct nla_policy ifa_mctp_policy[IFA_MAX + 1] = {
	[IFA_ADDRESS] = { .type = NLA_U8 },
	[IFA_LOCAL] = { .type = NLA_U8 },
	};

	static int mctp_rtm_newaddr(struct sk_buff skb, struct nlmsghdr nlh,
	struct netlink_ext_ack *extack)
	{
	struct net *net = sock_net(skb->sk);
	struct nlattr *tb[IFA_MAX + 1];
	struct net_device *dev;
	struct mctp_addr *addr;
	struct mctp_dev *mdev;
	struct ifaddrmsg *ifm;
	unsigned long flags;
	u8 *tmp_addrs;
	int rc;

	rc = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_mctp_policy,
	extack);
	if (rc < 0)
	return rc;

	ifm = nlmsg_data(nlh);

	if (tb[IFA_LOCAL])
	addr = nla_data(tb[IFA_LOCAL]);
	else if (tb[IFA_ADDRESS])
	addr = nla_data(tb[IFA_ADDRESS]);
	else
	return -EINVAL;

	/* find device */
	dev = __dev_get_by_index(net, ifm->ifa_index);
	if (!dev)
	return -ENODEV;

	mdev = mctp_dev_get_rtnl(dev);
	if (!mdev)
	return -ENODEV;

	if (!mctp_address_unicast(addr->s_addr))
	return -EINVAL;

	/* Prevent duplicates. Under RTNL so don't need to lock for reading */
	if (memchr(mdev->addrs, addr->s_addr, mdev->num_addrs))
	return -EEXIST;

	tmp_addrs = kmalloc(mdev->num_addrs + 1, GFP_KERNEL);
	if (!tmp_addrs)
	return -ENOMEM;
	memcpy(tmp_addrs, mdev->addrs, mdev->num_addrs);
	tmp_addrs[mdev->num_addrs] = addr->s_addr;

	/* Lock to write */
	spin_lock_irqsave(&mdev->addrs_lock, flags);
	mdev->num_addrs++;
	swap(mdev->addrs, tmp_addrs);
	spin_unlock_irqrestore(&mdev->addrs_lock, flags);

	kfree(tmp_addrs);

	mctp_addr_notify(mdev, addr->s_addr, RTM_NEWADDR, skb, nlh);
	mctp_route_add_local(mdev, addr->s_addr);

	return 0;
	}

	static int mctp_rtm_deladdr(struct sk_buff skb, struct nlmsghdr nlh,
	struct netlink_ext_ack *extack)
	{
	struct net *net = sock_net(skb->sk);
	struct nlattr *tb[IFA_MAX + 1];
	struct net_device *dev;
	struct mctp_addr *addr;
	struct mctp_dev *mdev;
	struct ifaddrmsg *ifm;
	unsigned long flags;
	u8 *pos;
	int rc;

	rc = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_mctp_policy,
	extack);
	if (rc < 0)
	return rc;

	ifm = nlmsg_data(nlh);

	if (tb[IFA_LOCAL])
	addr = nla_data(tb[IFA_LOCAL]);
	else if (tb[IFA_ADDRESS])
	addr = nla_data(tb[IFA_ADDRESS]);
	else
	return -EINVAL;

	/* find device */
	dev = __dev_get_by_index(net, ifm->ifa_index);
	if (!dev)
	return -ENODEV;

	mdev = mctp_dev_get_rtnl(dev);
	if (!mdev)
	return -ENODEV;

	pos = memchr(mdev->addrs, addr->s_addr, mdev->num_addrs);
	if (!pos)
	return -ENOENT;

	rc = mctp_route_remove_local(mdev, addr->s_addr);
	// we can ignore -ENOENT in the case a route was already removed
	if (rc < 0 && rc != -ENOENT)
	return rc;

	spin_lock_irqsave(&mdev->addrs_lock, flags);
	memmove(pos, pos + 1, mdev->num_addrs - 1 - (pos - mdev->addrs));
	mdev->num_addrs--;
	spin_unlock_irqrestore(&mdev->addrs_lock, flags);

	mctp_addr_notify(mdev, addr->s_addr, RTM_DELADDR, skb, nlh);

	return 0;
	}

	void mctp_dev_hold(struct mctp_dev *mdev)
	{
	refcount_inc(&mdev->refs);
	}

	void mctp_dev_put(struct mctp_dev *mdev)
	{
	if (mdev && refcount_dec_and_test(&mdev->refs)) {
	kfree(mdev->addrs);
	dev_put(mdev->dev);
	kfree_rcu(mdev, rcu);
	}
	}

	void mctp_dev_release_key(struct mctp_dev dev, struct mctp_sk_key key)
	__must_hold(&key->lock)
	{
	if (!dev)
	return;
	if (dev->ops && dev->ops->release_flow)
	dev->ops->release_flow(dev, key);
	key->dev = NULL;
	mctp_dev_put(dev);
	}

	void mctp_dev_set_key(struct mctp_dev dev, struct mctp_sk_key key)
	__must_hold(&key->lock)
	{
	mctp_dev_hold(dev);
	key->dev = dev;
	}

	static struct mctp_dev mctp_add_dev(struct net_device dev)
	{
	struct mctp_dev *mdev;

	ASSERT_RTNL();

	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
	if (!mdev)
	return ERR_PTR(-ENOMEM);

	spin_lock_init(&mdev->addrs_lock);

	mdev->net = mctp_default_net(dev_net(dev));

	/* associate to net_device */
	refcount_set(&mdev->refs, 1);
	rcu_assign_pointer(dev->mctp_ptr, mdev);

	dev_hold(dev);
	mdev->dev = dev;

	return mdev;
	}

	static int mctp_fill_link_af(struct sk_buff *skb,
	const struct net_device *dev, u32 ext_filter_mask)
	{
	struct mctp_dev *mdev;

	mdev = mctp_dev_get_rtnl(dev);
	if (!mdev)
	return -ENODATA;
	if (nla_put_u32(skb, IFLA_MCTP_NET, mdev->net))
	return -EMSGSIZE;
	return 0;
	}

	static size_t mctp_get_link_af_size(const struct net_device *dev,
	u32 ext_filter_mask)
	{
	struct mctp_dev *mdev;
	unsigned int ret;

	/* caller holds RCU */
	mdev = __mctp_dev_get(dev);
	if (!mdev)
	return 0;
	ret = nla_total_size(4); /* IFLA_MCTP_NET */
	mctp_dev_put(mdev);
	return ret;
	}

	static const struct nla_policy ifla_af_mctp_policy[IFLA_MCTP_MAX + 1] = {
	[IFLA_MCTP_NET] = { .type = NLA_U32 },
	};

	static int mctp_set_link_af(struct net_device dev, const struct nlattr attr,
	struct netlink_ext_ack *extack)
	{
	struct nlattr *tb[IFLA_MCTP_MAX + 1];
	struct mctp_dev *mdev;
	int rc;

	rc = nla_parse_nested(tb, IFLA_MCTP_MAX, attr, ifla_af_mctp_policy,
	NULL);
	if (rc)
	return rc;

	mdev = mctp_dev_get_rtnl(dev);
	if (!mdev)
	return 0;

	if (tb[IFLA_MCTP_NET])
	WRITE_ONCE(mdev->net, nla_get_u32(tb[IFLA_MCTP_NET]));

	return 0;
	}

	/* Matches netdev types that should have MCTP handling */
	static bool mctp_known(struct net_device *dev)
	{
	/* only register specific types (inc. NONE for TUN devices) */
	return dev->type == ARPHRD_MCTP \|\|
	dev->type == ARPHRD_LOOPBACK \|\|
	dev->type == ARPHRD_NONE;
	}

	static void mctp_unregister(struct net_device *dev)
	{
	struct mctp_dev *mdev;

	mdev = mctp_dev_get_rtnl(dev);
	if (!mdev)
	return;

	RCU_INIT_POINTER(mdev->dev->mctp_ptr, NULL);

	mctp_route_remove_dev(mdev);
	mctp_neigh_remove_dev(mdev);

	mctp_dev_put(mdev);
	}

	static int mctp_register(struct net_device *dev)
	{
	struct mctp_dev *mdev;

	/* Already registered? */
	if (rtnl_dereference(dev->mctp_ptr))
	return 0;

	/* only register specific types */
	if (!mctp_known(dev))
	return 0;

	mdev = mctp_add_dev(dev);
	if (IS_ERR(mdev))
	return PTR_ERR(mdev);

	return 0;
	}

	static int mctp_dev_notify(struct notifier_block *this, unsigned long event,
	void *ptr)
	{
	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
	int rc;

	switch (event) {
	case NETDEV_REGISTER:
	rc = mctp_register(dev);
	if (rc)
	return notifier_from_errno(rc);
	break;
	case NETDEV_UNREGISTER:
	mctp_unregister(dev);
	break;
	}

	return NOTIFY_OK;
	}

	static int mctp_register_netdevice(struct net_device *dev,
	const struct mctp_netdev_ops *ops)
	{
	struct mctp_dev *mdev;

	mdev = mctp_add_dev(dev);
	if (IS_ERR(mdev))
	return PTR_ERR(mdev);

	mdev->ops = ops;

	return register_netdevice(dev);
	}

	int mctp_register_netdev(struct net_device *dev,
	const struct mctp_netdev_ops *ops)
	{
	int rc;

	rtnl_lock();
	rc = mctp_register_netdevice(dev, ops);
	rtnl_unlock();

	return rc;
	}
	EXPORT_SYMBOL_GPL(mctp_register_netdev);

	void mctp_unregister_netdev(struct net_device *dev)
	{
	unregister_netdev(dev);
	}
	EXPORT_SYMBOL_GPL(mctp_unregister_netdev);

	static struct rtnl_af_ops mctp_af_ops = {
	.family = AF_MCTP,
	.fill_link_af = mctp_fill_link_af,
	.get_link_af_size = mctp_get_link_af_size,
	.set_link_af = mctp_set_link_af,
	};

	static struct notifier_block mctp_dev_nb = {
	.notifier_call = mctp_dev_notify,
	.priority = ADDRCONF_NOTIFY_PRIORITY,
	};

	static const struct rtnl_msg_handler mctp_device_rtnl_msg_handlers[] = {
	{THIS_MODULE, PF_MCTP, RTM_NEWADDR, mctp_rtm_newaddr, NULL, 0},
	{THIS_MODULE, PF_MCTP, RTM_DELADDR, mctp_rtm_deladdr, NULL, 0},
	{THIS_MODULE, PF_MCTP, RTM_GETADDR, NULL, mctp_dump_addrinfo, 0},
	};

	int __init mctp_device_init(void)
	{
	int err;

	register_netdevice_notifier(&mctp_dev_nb);
	rtnl_af_register(&mctp_af_ops);

	err = rtnl_register_many(mctp_device_rtnl_msg_handlers);
	if (err) {
	rtnl_af_unregister(&mctp_af_ops);
	unregister_netdevice_notifier(&mctp_dev_nb);
	}

	return err;
	}

	void __exit mctp_device_exit(void)
	{
	rtnl_unregister_many(mctp_device_rtnl_msg_handlers);
	rtnl_af_unregister(&mctp_af_ops);
	unregister_netdevice_notifier(&mctp_dev_nb);
	}