Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 1308 insertions, 0 deletions

diff --git a/drivers/net/netkit.c b/drivers/net/netkit.c
new file mode 100644
index 000000000..a3931cd82
--- /dev/null
+++ b/drivers/net/netkit.c
@@ -0,0 +1,1308 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2023 Isovalent */
+
+#include <linux/netdevice.h>
+#include <linux/ethtool.h>
+#include <linux/etherdevice.h>
+#include <linux/filter.h>
+#include <linux/netfilter_netdev.h>
+#include <linux/bpf_mprog.h>
+#include <linux/indirect_call_wrapper.h>
+
+#include <net/netdev_lock.h>
+#include <net/netdev_queues.h>
+#include <net/netdev_rx_queue.h>
+#include <net/xdp_sock_drv.h>
+#include <net/netkit.h>
+#include <net/dst.h>
+#include <net/tcx.h>
+
+#define NETKIT_DRV_NAME	"netkit"
+
+#define NETKIT_NUM_RX_QUEUES_MAX  1024
+#define NETKIT_NUM_TX_QUEUES_MAX  1
+
+#define NETKIT_NUM_RX_QUEUES_REAL 1
+#define NETKIT_NUM_TX_QUEUES_REAL 1
+
+struct netkit {
+	__cacheline_group_begin(netkit_fastpath);
+	struct net_device __rcu *peer;
+	struct bpf_mprog_entry __rcu *active;
+	enum netkit_action policy;
+	enum netkit_scrub scrub;
+	struct bpf_mprog_bundle	bundle;
+	__cacheline_group_end(netkit_fastpath);
+
+	__cacheline_group_begin(netkit_slowpath);
+	enum netkit_mode mode;
+	enum netkit_pairing pair;
+	bool primary;
+	u32 headroom;
+	__cacheline_group_end(netkit_slowpath);
+};
+
+struct netkit_link {
+	struct bpf_link link;
+	struct net_device *dev;
+};
+
+static struct rtnl_link_ops netkit_link_ops;
+
+static __always_inline int
+netkit_run(const struct bpf_mprog_entry *entry, struct sk_buff *skb,
+	   enum netkit_action ret)
+{
+	const struct bpf_mprog_fp *fp;
+	const struct bpf_prog *prog;
+
+	bpf_mprog_foreach_prog(entry, fp, prog) {
+		bpf_compute_data_pointers(skb);
+		ret = bpf_prog_run(prog, skb);
+		if (ret != NETKIT_NEXT)
+			break;
+	}
+	return ret;
+}
+
+static void netkit_xnet(struct sk_buff *skb)
+{
+	skb->priority = 0;
+	skb->mark = 0;
+}
+
+static void netkit_prep_forward(struct sk_buff *skb,
+				bool xnet, bool xnet_scrub)
+{
+	skb_scrub_packet(skb, false);
+	nf_skip_egress(skb, true);
+	skb_reset_mac_header(skb);
+	if (!xnet)
+		return;
+	skb_clear_tstamp(skb);
+	if (xnet_scrub)
+		netkit_xnet(skb);
+}
+
+static struct netkit *netkit_priv(const struct net_device *dev)
+{
+	return netdev_priv(dev);
+}
+
+static netdev_tx_t netkit_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct bpf_net_context __bpf_net_ctx, *bpf_net_ctx;
+	struct netkit *nk = netkit_priv(dev);
+	enum netkit_action ret = READ_ONCE(nk->policy);
+	netdev_tx_t ret_dev = NET_XMIT_SUCCESS;
+	const struct bpf_mprog_entry *entry;
+	struct net_device *peer;
+	int len = skb->len;
+
+	bpf_net_ctx = bpf_net_ctx_set(&__bpf_net_ctx);
+	rcu_read_lock();
+	peer = rcu_dereference(nk->peer);
+	if (unlikely(!peer || !(peer->flags & IFF_UP) ||
+		     !pskb_may_pull(skb, ETH_HLEN) ||
+		     skb_orphan_frags(skb, GFP_ATOMIC)))
+		goto drop;
+	netkit_prep_forward(skb, !net_eq(dev_net(dev), dev_net(peer)),
+			    nk->scrub);
+	eth_skb_pkt_type(skb, peer);
+	skb->dev = peer;
+	entry = rcu_dereference(nk->active);
+	if (entry)
+		ret = netkit_run(entry, skb, ret);
+	switch (ret) {
+	case NETKIT_NEXT:
+	case NETKIT_PASS:
+		eth_skb_pull_mac(skb);
+		skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
+		if (likely(__netif_rx(skb) == NET_RX_SUCCESS)) {
+			dev_sw_netstats_tx_add(dev, 1, len);
+			dev_sw_netstats_rx_add(peer, len);
+		} else {
+			goto drop_stats;
+		}
+		break;
+	case NETKIT_REDIRECT:
+		dev_sw_netstats_tx_add(dev, 1, len);
+		skb_do_redirect(skb);
+		break;
+	case NETKIT_DROP:
+	default:
+drop:
+		kfree_skb(skb);
+drop_stats:
+		dev_core_stats_tx_dropped_inc(dev);
+		ret_dev = NET_XMIT_DROP;
+		break;
+	}
+	rcu_read_unlock();
+	bpf_net_ctx_clear(bpf_net_ctx);
+	return ret_dev;
+}
+
+static int netkit_open(struct net_device *dev)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct net_device *peer = rtnl_dereference(nk->peer);
+
+	if (nk->pair == NETKIT_DEVICE_SINGLE) {
+		netif_carrier_on(dev);
+		return 0;
+	}
+	if (!peer)
+		return -ENOTCONN;
+	if (peer->flags & IFF_UP) {
+		netif_carrier_on(dev);
+		netif_carrier_on(peer);
+	}
+	return 0;
+}
+
+static int netkit_close(struct net_device *dev)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct net_device *peer = rtnl_dereference(nk->peer);
+
+	netif_carrier_off(dev);
+	if (peer)
+		netif_carrier_off(peer);
+	return 0;
+}
+
+static int netkit_get_iflink(const struct net_device *dev)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct net_device *peer;
+	int iflink = 0;
+
+	rcu_read_lock();
+	peer = rcu_dereference(nk->peer);
+	if (peer)
+		iflink = READ_ONCE(peer->ifindex);
+	rcu_read_unlock();
+	return iflink;
+}
+
+static int netkit_set_multicast(struct net_device *dev,
+				struct netdev_hw_addr_list *uc,
+				struct netdev_hw_addr_list *mc)
+{
+	/* Nothing to do, we receive whatever gets pushed to us! */
+	return 0;
+}
+
+static int netkit_set_macaddr(struct net_device *dev, void *sa)
+{
+	struct netkit *nk = netkit_priv(dev);
+
+	if (nk->mode != NETKIT_L2)
+		return -EOPNOTSUPP;
+
+	return eth_mac_addr(dev, sa);
+}
+
+static void netkit_set_headroom(struct net_device *dev, int headroom)
+{
+	struct netkit *nk = netkit_priv(dev), *nk2;
+	struct net_device *peer;
+
+	if (headroom < 0)
+		headroom = NET_SKB_PAD;
+
+	rcu_read_lock();
+	peer = rcu_dereference(nk->peer);
+	if (!peer) {
+		nk->headroom = headroom;
+		dev->needed_headroom = headroom;
+	} else {
+		nk2 = netkit_priv(peer);
+		nk->headroom = headroom;
+		headroom = max(nk->headroom, nk2->headroom);
+
+		peer->needed_headroom = headroom;
+		dev->needed_headroom = headroom;
+	}
+	rcu_read_unlock();
+}
+
+INDIRECT_CALLABLE_SCOPE struct net_device *netkit_peer_dev(struct net_device *dev)
+{
+	return rcu_dereference(netkit_priv(dev)->peer);
+}
+
+static void netkit_get_stats(struct net_device *dev,
+			     struct rtnl_link_stats64 *stats)
+{
+	dev_fetch_sw_netstats(stats, dev->tstats);
+	stats->tx_dropped = DEV_STATS_READ(dev, tx_dropped);
+}
+
+static bool netkit_xsk_supported_at_phys(const struct net_device *dev)
+{
+	if (!dev->netdev_ops->ndo_bpf ||
+	    !dev->netdev_ops->ndo_xdp_xmit ||
+	    !dev->netdev_ops->ndo_xsk_wakeup)
+		return false;
+	return true;
+}
+
+static int netkit_xsk(struct net_device *dev, struct netdev_bpf *xdp)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct netdev_bpf xdp_lower;
+	struct netdev_rx_queue *rxq;
+	struct net_device *phys;
+	bool create = false;
+	int ret = -EBUSY;
+
+	switch (xdp->command) {
+	case XDP_SETUP_XSK_POOL:
+		if (nk->pair == NETKIT_DEVICE_PAIR)
+			return -EOPNOTSUPP;
+		if (xdp->xsk.queue_id >= dev->real_num_rx_queues)
+			return -EINVAL;
+
+		rxq = __netif_get_rx_queue(dev, xdp->xsk.queue_id);
+		if (!rxq->lease)
+			return -EOPNOTSUPP;
+
+		phys = rxq->lease->dev;
+		if (!netkit_xsk_supported_at_phys(phys))
+			return -EOPNOTSUPP;
+
+		create = xdp->xsk.pool;
+		memcpy(&xdp_lower, xdp, sizeof(xdp_lower));
+		xdp_lower.xsk.queue_id = get_netdev_rx_queue_index(rxq->lease);
+		break;
+	case XDP_SETUP_PROG:
+		return -EOPNOTSUPP;
+	default:
+		return -EINVAL;
+	}
+
+	netdev_lock(phys);
+	if (create &&
+	    (phys->xdp_features & NETDEV_XDP_ACT_XSK) != NETDEV_XDP_ACT_XSK) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+	if (!create || !dev_get_min_mp_channel_count(phys))
+		ret = phys->netdev_ops->ndo_bpf(phys, &xdp_lower);
+out:
+	netdev_unlock(phys);
+	return ret;
+}
+
+static int netkit_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
+{
+	struct netdev_rx_queue *rxq, *rxq_lease;
+	struct net_device *phys;
+
+	if (queue_id >= dev->real_num_rx_queues)
+		return -EINVAL;
+
+	rxq = __netif_get_rx_queue(dev, queue_id);
+	rxq_lease = READ_ONCE(rxq->lease);
+	if (unlikely(!rxq_lease))
+		return -EOPNOTSUPP;
+
+	/* netkit_xsk already validated full xsk support, hence it's
+	 * fine to call into ndo_xsk_wakeup right away given this
+	 * was a prerequisite to get here in the first place. The
+	 * phys xsk support cannot change without tearing down the
+	 * device (which clears the lease first).
+	 */
+	phys = rxq_lease->dev;
+	return phys->netdev_ops->ndo_xsk_wakeup(phys,
+			get_netdev_rx_queue_index(rxq_lease), flags);
+}
+
+static int netkit_init(struct net_device *dev)
+{
+	netdev_lockdep_set_classes(dev);
+	return 0;
+}
+
+static void netkit_uninit(struct net_device *dev);
+
+static const struct net_device_ops netkit_netdev_ops = {
+	.ndo_init		= netkit_init,
+	.ndo_open		= netkit_open,
+	.ndo_stop		= netkit_close,
+	.ndo_start_xmit		= netkit_xmit,
+	.ndo_set_rx_mode_async	= netkit_set_multicast,
+	.ndo_set_rx_headroom	= netkit_set_headroom,
+	.ndo_set_mac_address	= netkit_set_macaddr,
+	.ndo_get_iflink		= netkit_get_iflink,
+	.ndo_get_peer_dev	= netkit_peer_dev,
+	.ndo_get_stats64	= netkit_get_stats,
+	.ndo_uninit		= netkit_uninit,
+	.ndo_bpf		= netkit_xsk,
+	.ndo_xsk_wakeup		= netkit_xsk_wakeup,
+	.ndo_features_check	= passthru_features_check,
+};
+
+static void netkit_get_drvinfo(struct net_device *dev,
+			       struct ethtool_drvinfo *info)
+{
+	strscpy(info->driver, NETKIT_DRV_NAME, sizeof(info->driver));
+}
+
+static const struct ethtool_ops netkit_ethtool_ops = {
+	.get_drvinfo		= netkit_get_drvinfo,
+};
+
+static int netkit_queue_create(struct net_device *dev,
+			       struct netlink_ext_ack *extack)
+{
+	struct netkit *nk = netkit_priv(dev);
+	u32 rxq_count_old, rxq_count_new;
+	int err;
+
+	rxq_count_old = dev->real_num_rx_queues;
+	rxq_count_new = rxq_count_old + 1;
+
+	/* In paired mode, only the non-primary (peer) device can
+	 * create leased queues since the primary is the management
+	 * side. In single device mode, leasing is always allowed.
+	 */
+	if (nk->pair == NETKIT_DEVICE_PAIR && nk->primary) {
+		NL_SET_ERR_MSG(extack,
+			       "netkit can only lease against the peer device");
+		return -EOPNOTSUPP;
+	}
+
+	err = netif_set_real_num_rx_queues(dev, rxq_count_new);
+	if (err) {
+		if (rxq_count_new > dev->num_rx_queues)
+			NL_SET_ERR_MSG(extack,
+				       "netkit maximum queue limit reached");
+		else
+			NL_SET_ERR_MSG_FMT(extack,
+					   "netkit cannot create more queues err=%d", err);
+		return err;
+	}
+
+	return rxq_count_old;
+}
+
+static const struct netdev_queue_mgmt_ops netkit_queue_mgmt_ops = {
+	.ndo_queue_create	= netkit_queue_create,
+};
+
+static struct net_device *netkit_alloc(struct nlattr *tb[],
+				       const char *ifname,
+				       unsigned char name_assign_type,
+				       unsigned int num_tx_queues,
+				       unsigned int num_rx_queues)
+{
+	const struct rtnl_link_ops *ops = &netkit_link_ops;
+	struct net_device *dev;
+
+	if (num_tx_queues > NETKIT_NUM_TX_QUEUES_MAX ||
+	    num_rx_queues > NETKIT_NUM_RX_QUEUES_MAX)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	dev = alloc_netdev_mqs(ops->priv_size, ifname,
+			       name_assign_type, ops->setup,
+			       num_tx_queues, num_rx_queues);
+	if (dev) {
+		dev->real_num_tx_queues = NETKIT_NUM_TX_QUEUES_REAL;
+		dev->real_num_rx_queues = NETKIT_NUM_RX_QUEUES_REAL;
+	}
+	return dev;
+}
+
+static void netkit_queue_unlease(struct net_device *dev)
+{
+	struct netdev_rx_queue *rxq, *rxq_lease;
+	struct net_device *dev_lease;
+	int i;
+
+	if (dev->real_num_rx_queues == 1)
+		return;
+
+	netdev_lock(dev);
+	for (i = 1; i < dev->real_num_rx_queues; i++) {
+		rxq = __netif_get_rx_queue(dev, i);
+		rxq_lease = rxq->lease;
+		dev_lease = rxq_lease->dev;
+
+		netdev_lock(dev_lease);
+		netdev_rx_queue_unlease(rxq, rxq_lease);
+		netdev_unlock(dev_lease);
+	}
+	netdev_unlock(dev);
+}
+
+static void netkit_setup(struct net_device *dev)
+{
+	static const netdev_features_t netkit_features_hw_vlan =
+		NETIF_F_HW_VLAN_CTAG_TX |
+		NETIF_F_HW_VLAN_CTAG_RX |
+		NETIF_F_HW_VLAN_STAG_TX |
+		NETIF_F_HW_VLAN_STAG_RX;
+	static const netdev_features_t netkit_features =
+		netkit_features_hw_vlan |
+		NETIF_F_SG |
+		NETIF_F_FRAGLIST |
+		NETIF_F_HW_CSUM |
+		NETIF_F_RXCSUM |
+		NETIF_F_SCTP_CRC |
+		NETIF_F_HIGHDMA |
+		NETIF_F_GSO_SOFTWARE |
+		NETIF_F_GSO_ENCAP_ALL;
+
+	ether_setup(dev);
+	dev->max_mtu = ETH_MAX_MTU;
+	dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
+
+	dev->flags |= IFF_NOARP;
+	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;
+	dev->priv_flags |= IFF_PHONY_HEADROOM;
+	dev->priv_flags |= IFF_NO_QUEUE;
+	dev->priv_flags |= IFF_DISABLE_NETPOLL;
+	dev->lltx = true;
+	dev->netmem_tx = NETMEM_TX_NO_DMA;
+
+	dev->netdev_ops     = &netkit_netdev_ops;
+	dev->ethtool_ops    = &netkit_ethtool_ops;
+	dev->queue_mgmt_ops = &netkit_queue_mgmt_ops;
+
+	dev->features |= netkit_features;
+	dev->hw_features = netkit_features;
+	dev->hw_enc_features = netkit_features;
+	dev->mpls_features = NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE;
+	dev->vlan_features = dev->features & ~netkit_features_hw_vlan;
+
+	dev->needs_free_netdev = true;
+
+	netif_set_tso_max_size(dev, GSO_MAX_SIZE);
+}
+
+static struct net *netkit_get_link_net(const struct net_device *dev)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct net_device *peer = rtnl_dereference(nk->peer);
+
+	return peer ? dev_net(peer) : dev_net(dev);
+}
+
+static int netkit_check_policy(int policy, struct nlattr *tb,
+			       struct netlink_ext_ack *extack)
+{
+	switch (policy) {
+	case NETKIT_PASS:
+	case NETKIT_DROP:
+		return 0;
+	default:
+		NL_SET_ERR_MSG_ATTR(extack, tb,
+				    "Provided default xmit policy not supported");
+		return -EINVAL;
+	}
+}
+
+static int netkit_validate(struct nlattr *tb[], struct nlattr *data[],
+			   struct netlink_ext_ack *extack)
+{
+	struct nlattr *attr = tb[IFLA_ADDRESS];
+
+	if (!attr)
+		return 0;
+	if (nla_len(attr) != ETH_ALEN)
+		return -EINVAL;
+	if (!is_valid_ether_addr(nla_data(attr)))
+		return -EADDRNOTAVAIL;
+	return 0;
+}
+
+static int netkit_new_link(struct net_device *dev,
+			   struct rtnl_newlink_params *params,
+			   struct netlink_ext_ack *extack)
+{
+	struct net *peer_net = rtnl_newlink_peer_net(params);
+	enum netkit_scrub scrub_prim = NETKIT_SCRUB_DEFAULT;
+	enum netkit_scrub scrub_peer = NETKIT_SCRUB_DEFAULT;
+	struct nlattr *peer_tb[IFLA_MAX + 1], **tbp, *attr;
+	enum netkit_pairing pair = NETKIT_DEVICE_PAIR;
+	enum netkit_action policy_prim = NETKIT_PASS;
+	enum netkit_action policy_peer = NETKIT_PASS;
+	bool seen_peer = false, seen_scrub = false;
+	struct nlattr **data = params->data;
+	enum netkit_mode mode = NETKIT_L3;
+	unsigned char ifname_assign_type;
+	struct nlattr **tb = params->tb;
+	u16 headroom = 0, tailroom = 0;
+	struct ifinfomsg *ifmp = NULL;
+	struct net_device *peer = NULL;
+	char ifname[IFNAMSIZ];
+	struct netkit *nk;
+	int err;
+
+	tbp = tb;
+	if (data) {
+		if (data[IFLA_NETKIT_MODE])
+			mode = nla_get_u32(data[IFLA_NETKIT_MODE]);
+		if (data[IFLA_NETKIT_PEER_INFO]) {
+			attr = data[IFLA_NETKIT_PEER_INFO];
+			ifmp = nla_data(attr);
+			rtnl_nla_parse_ifinfomsg(peer_tb, attr, extack);
+			tbp = peer_tb;
+		}
+		if (data[IFLA_NETKIT_SCRUB])
+			scrub_prim = nla_get_u32(data[IFLA_NETKIT_SCRUB]);
+		if (data[IFLA_NETKIT_PEER_SCRUB])
+			scrub_peer = nla_get_u32(data[IFLA_NETKIT_PEER_SCRUB]);
+		if (data[IFLA_NETKIT_POLICY]) {
+			attr = data[IFLA_NETKIT_POLICY];
+			policy_prim = nla_get_u32(attr);
+			err = netkit_check_policy(policy_prim, attr, extack);
+			if (err < 0)
+				return err;
+		}
+		if (data[IFLA_NETKIT_PEER_POLICY]) {
+			attr = data[IFLA_NETKIT_PEER_POLICY];
+			policy_peer = nla_get_u32(attr);
+			err = netkit_check_policy(policy_peer, attr, extack);
+			if (err < 0)
+				return err;
+		}
+		if (data[IFLA_NETKIT_HEADROOM])
+			headroom = nla_get_u16(data[IFLA_NETKIT_HEADROOM]);
+		if (data[IFLA_NETKIT_TAILROOM])
+			tailroom = nla_get_u16(data[IFLA_NETKIT_TAILROOM]);
+		if (data[IFLA_NETKIT_PAIRING])
+			pair = nla_get_u32(data[IFLA_NETKIT_PAIRING]);
+
+		seen_scrub = data[IFLA_NETKIT_SCRUB];
+		seen_peer = data[IFLA_NETKIT_PEER_INFO] ||
+			    data[IFLA_NETKIT_PEER_SCRUB] ||
+			    data[IFLA_NETKIT_PEER_POLICY];
+	}
+
+	if (ifmp && tbp[IFLA_IFNAME]) {
+		nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
+		ifname_assign_type = NET_NAME_USER;
+	} else {
+		strscpy(ifname, "nk%d", IFNAMSIZ);
+		ifname_assign_type = NET_NAME_ENUM;
+	}
+	if (mode != NETKIT_L2 &&
+	    (tb[IFLA_ADDRESS] || tbp[IFLA_ADDRESS]))
+		return -EOPNOTSUPP;
+	if (pair == NETKIT_DEVICE_SINGLE &&
+	    (tb != tbp || seen_peer || seen_scrub ||
+	     policy_prim != NETKIT_PASS))
+		return -EOPNOTSUPP;
+
+	if (pair == NETKIT_DEVICE_PAIR) {
+		peer = rtnl_create_link(peer_net, ifname, ifname_assign_type,
+					&netkit_link_ops, tbp, extack);
+		if (IS_ERR(peer))
+			return PTR_ERR(peer);
+
+		netif_inherit_tso_max(peer, dev);
+		if (headroom)
+			peer->needed_headroom = headroom;
+		if (tailroom)
+			peer->needed_tailroom = tailroom;
+		if (mode == NETKIT_L2 && !(ifmp && tbp[IFLA_ADDRESS]))
+			eth_hw_addr_random(peer);
+		if (ifmp && dev->ifindex)
+			peer->ifindex = ifmp->ifi_index;
+
+		nk = netkit_priv(peer);
+		nk->primary = false;
+		nk->policy = policy_peer;
+		nk->scrub = scrub_peer;
+		nk->mode = mode;
+		nk->pair = pair;
+		nk->headroom = headroom;
+		bpf_mprog_bundle_init(&nk->bundle);
+
+		err = register_netdevice(peer);
+		if (err < 0)
+			goto err_register_peer;
+		netif_carrier_off(peer);
+		if (mode == NETKIT_L2)
+			dev_change_flags(peer, peer->flags & ~IFF_NOARP, NULL);
+
+		err = rtnl_configure_link(peer, NULL, 0, NULL);
+		if (err < 0)
+			goto err_configure_peer;
+	}
+
+	if (mode == NETKIT_L2 && !tb[IFLA_ADDRESS])
+		eth_hw_addr_random(dev);
+	if (tb[IFLA_IFNAME])
+		nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
+	else
+		strscpy(dev->name, "nk%d", IFNAMSIZ);
+	if (headroom)
+		dev->needed_headroom = headroom;
+	if (tailroom)
+		dev->needed_tailroom = tailroom;
+
+	nk = netkit_priv(dev);
+	nk->primary = true;
+	nk->policy = policy_prim;
+	nk->scrub = scrub_prim;
+	nk->mode = mode;
+	nk->pair = pair;
+	nk->headroom = headroom;
+	bpf_mprog_bundle_init(&nk->bundle);
+
+	if (pair == NETKIT_DEVICE_SINGLE)
+		xdp_set_features_flag(dev, NETDEV_XDP_ACT_XSK);
+
+	err = register_netdevice(dev);
+	if (err < 0)
+		goto err_configure_peer;
+	netif_carrier_off(dev);
+	if (mode == NETKIT_L2)
+		dev_change_flags(dev, dev->flags & ~IFF_NOARP, NULL);
+
+	rcu_assign_pointer(netkit_priv(dev)->peer, peer);
+	if (peer)
+		rcu_assign_pointer(netkit_priv(peer)->peer, dev);
+	return 0;
+err_configure_peer:
+	if (peer)
+		unregister_netdevice(peer);
+	return err;
+err_register_peer:
+	free_netdev(peer);
+	return err;
+}
+
+static struct bpf_mprog_entry *netkit_entry_fetch(struct net_device *dev,
+						  bool bundle_fallback)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct bpf_mprog_entry *entry;
+
+	ASSERT_RTNL();
+	entry = rcu_dereference_rtnl(nk->active);
+	if (entry)
+		return entry;
+	if (bundle_fallback)
+		return &nk->bundle.a;
+	return NULL;
+}
+
+static void netkit_entry_update(struct net_device *dev,
+				struct bpf_mprog_entry *entry)
+{
+	struct netkit *nk = netkit_priv(dev);
+
+	ASSERT_RTNL();
+	rcu_assign_pointer(nk->active, entry);
+}
+
+static void netkit_entry_sync(void)
+{
+	synchronize_rcu();
+}
+
+static struct net_device *netkit_dev_fetch(struct net *net, u32 ifindex, u32 which)
+{
+	struct net_device *dev;
+	struct netkit *nk;
+
+	ASSERT_RTNL();
+
+	switch (which) {
+	case BPF_NETKIT_PRIMARY:
+	case BPF_NETKIT_PEER:
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	dev = __dev_get_by_index(net, ifindex);
+	if (!dev)
+		return ERR_PTR(-ENODEV);
+	if (dev->netdev_ops != &netkit_netdev_ops)
+		return ERR_PTR(-ENXIO);
+
+	nk = netkit_priv(dev);
+	if (!nk->primary)
+		return ERR_PTR(-EACCES);
+	if (nk->pair == NETKIT_DEVICE_SINGLE)
+		return ERR_PTR(-EOPNOTSUPP);
+	if (which == BPF_NETKIT_PEER) {
+		dev = rcu_dereference_rtnl(nk->peer);
+		if (!dev)
+			return ERR_PTR(-ENODEV);
+	}
+	return dev;
+}
+
+int netkit_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+	struct bpf_mprog_entry *entry, *entry_new;
+	struct bpf_prog *replace_prog = NULL;
+	struct net_device *dev;
+	int ret;
+
+	rtnl_lock();
+	dev = netkit_dev_fetch(current->nsproxy->net_ns, attr->target_ifindex,
+			       attr->attach_type);
+	if (IS_ERR(dev)) {
+		ret = PTR_ERR(dev);
+		goto out;
+	}
+	entry = netkit_entry_fetch(dev, true);
+	if (attr->attach_flags & BPF_F_REPLACE) {
+		replace_prog = bpf_prog_get_type(attr->replace_bpf_fd,
+						 prog->type);
+		if (IS_ERR(replace_prog)) {
+			ret = PTR_ERR(replace_prog);
+			replace_prog = NULL;
+			goto out;
+		}
+	}
+	ret = bpf_mprog_attach(entry, &entry_new, prog, NULL, replace_prog,
+			       attr->attach_flags, attr->relative_fd,
+			       attr->expected_revision);
+	if (!ret) {
+		if (entry != entry_new) {
+			netkit_entry_update(dev, entry_new);
+			netkit_entry_sync();
+		}
+		bpf_mprog_commit(entry);
+	}
+out:
+	if (replace_prog)
+		bpf_prog_put(replace_prog);
+	rtnl_unlock();
+	return ret;
+}
+
+int netkit_prog_detach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+	struct bpf_mprog_entry *entry, *entry_new;
+	struct net_device *dev;
+	int ret;
+
+	rtnl_lock();
+	dev = netkit_dev_fetch(current->nsproxy->net_ns, attr->target_ifindex,
+			       attr->attach_type);
+	if (IS_ERR(dev)) {
+		ret = PTR_ERR(dev);
+		goto out;
+	}
+	entry = netkit_entry_fetch(dev, false);
+	if (!entry) {
+		ret = -ENOENT;
+		goto out;
+	}
+	ret = bpf_mprog_detach(entry, &entry_new, prog, NULL, attr->attach_flags,
+			       attr->relative_fd, attr->expected_revision);
+	if (!ret) {
+		if (!bpf_mprog_total(entry_new))
+			entry_new = NULL;
+		netkit_entry_update(dev, entry_new);
+		netkit_entry_sync();
+		bpf_mprog_commit(entry);
+	}
+out:
+	rtnl_unlock();
+	return ret;
+}
+
+int netkit_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
+{
+	struct net_device *dev;
+	int ret;
+
+	rtnl_lock();
+	dev = netkit_dev_fetch(current->nsproxy->net_ns,
+			       attr->query.target_ifindex,
+			       attr->query.attach_type);
+	if (IS_ERR(dev)) {
+		ret = PTR_ERR(dev);
+		goto out;
+	}
+	ret = bpf_mprog_query(attr, uattr, netkit_entry_fetch(dev, false));
+out:
+	rtnl_unlock();
+	return ret;
+}
+
+static struct netkit_link *netkit_link(const struct bpf_link *link)
+{
+	return container_of(link, struct netkit_link, link);
+}
+
+static int netkit_link_prog_attach(struct bpf_link *link, u32 flags,
+				   u32 id_or_fd, u64 revision)
+{
+	struct netkit_link *nkl = netkit_link(link);
+	struct bpf_mprog_entry *entry, *entry_new;
+	struct net_device *dev = nkl->dev;
+	int ret;
+
+	ASSERT_RTNL();
+	entry = netkit_entry_fetch(dev, true);
+	ret = bpf_mprog_attach(entry, &entry_new, link->prog, link, NULL, flags,
+			       id_or_fd, revision);
+	if (!ret) {
+		if (entry != entry_new) {
+			netkit_entry_update(dev, entry_new);
+			netkit_entry_sync();
+		}
+		bpf_mprog_commit(entry);
+	}
+	return ret;
+}
+
+static void netkit_link_release(struct bpf_link *link)
+{
+	struct netkit_link *nkl = netkit_link(link);
+	struct bpf_mprog_entry *entry, *entry_new;
+	struct net_device *dev;
+	int ret = 0;
+
+	rtnl_lock();
+	dev = nkl->dev;
+	if (!dev)
+		goto out;
+	entry = netkit_entry_fetch(dev, false);
+	if (!entry) {
+		ret = -ENOENT;
+		goto out;
+	}
+	ret = bpf_mprog_detach(entry, &entry_new, link->prog, link, 0, 0, 0);
+	if (!ret) {
+		if (!bpf_mprog_total(entry_new))
+			entry_new = NULL;
+		netkit_entry_update(dev, entry_new);
+		netkit_entry_sync();
+		bpf_mprog_commit(entry);
+		nkl->dev = NULL;
+	}
+out:
+	WARN_ON_ONCE(ret);
+	rtnl_unlock();
+}
+
+static int netkit_link_update(struct bpf_link *link, struct bpf_prog *nprog,
+			      struct bpf_prog *oprog)
+{
+	struct netkit_link *nkl = netkit_link(link);
+	struct bpf_mprog_entry *entry, *entry_new;
+	struct net_device *dev;
+	int ret = 0;
+
+	rtnl_lock();
+	dev = nkl->dev;
+	if (!dev) {
+		ret = -ENOLINK;
+		goto out;
+	}
+	if (oprog && link->prog != oprog) {
+		ret = -EPERM;
+		goto out;
+	}
+	oprog = link->prog;
+	if (oprog == nprog) {
+		bpf_prog_put(nprog);
+		goto out;
+	}
+	entry = netkit_entry_fetch(dev, false);
+	if (!entry) {
+		ret = -ENOENT;
+		goto out;
+	}
+	ret = bpf_mprog_attach(entry, &entry_new, nprog, link, oprog,
+			       BPF_F_REPLACE | BPF_F_ID,
+			       link->prog->aux->id, 0);
+	if (!ret) {
+		WARN_ON_ONCE(entry != entry_new);
+		oprog = xchg(&link->prog, nprog);
+		bpf_prog_put(oprog);
+		bpf_mprog_commit(entry);
+	}
+out:
+	rtnl_unlock();
+	return ret;
+}
+
+static void netkit_link_dealloc(struct bpf_link *link)
+{
+	kfree(netkit_link(link));
+}
+
+static void netkit_link_fdinfo(const struct bpf_link *link, struct seq_file *seq)
+{
+	const struct netkit_link *nkl = netkit_link(link);
+	u32 ifindex = 0;
+
+	rtnl_lock();
+	if (nkl->dev)
+		ifindex = nkl->dev->ifindex;
+	rtnl_unlock();
+
+	seq_printf(seq, "ifindex:\t%u\n", ifindex);
+	seq_printf(seq, "attach_type:\t%u (%s)\n",
+		   link->attach_type,
+		   link->attach_type == BPF_NETKIT_PRIMARY ? "primary" : "peer");
+}
+
+static int netkit_link_fill_info(const struct bpf_link *link,
+				 struct bpf_link_info *info)
+{
+	const struct netkit_link *nkl = netkit_link(link);
+	u32 ifindex = 0;
+
+	rtnl_lock();
+	if (nkl->dev)
+		ifindex = nkl->dev->ifindex;
+	rtnl_unlock();
+
+	info->netkit.ifindex = ifindex;
+	info->netkit.attach_type = link->attach_type;
+	return 0;
+}
+
+static int netkit_link_detach(struct bpf_link *link)
+{
+	netkit_link_release(link);
+	return 0;
+}
+
+static const struct bpf_link_ops netkit_link_lops = {
+	.release	= netkit_link_release,
+	.detach		= netkit_link_detach,
+	.dealloc	= netkit_link_dealloc,
+	.update_prog	= netkit_link_update,
+	.show_fdinfo	= netkit_link_fdinfo,
+	.fill_link_info	= netkit_link_fill_info,
+};
+
+static int netkit_link_init(struct netkit_link *nkl,
+			    struct bpf_link_primer *link_primer,
+			    const union bpf_attr *attr,
+			    struct net_device *dev,
+			    struct bpf_prog *prog)
+{
+	bpf_link_init(&nkl->link, BPF_LINK_TYPE_NETKIT,
+		      &netkit_link_lops, prog, attr->link_create.attach_type);
+	nkl->dev = dev;
+	return bpf_link_prime(&nkl->link, link_primer);
+}
+
+int netkit_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+	struct bpf_link_primer link_primer;
+	struct netkit_link *nkl;
+	struct net_device *dev;
+	int ret;
+
+	rtnl_lock();
+	dev = netkit_dev_fetch(current->nsproxy->net_ns,
+			       attr->link_create.target_ifindex,
+			       attr->link_create.attach_type);
+	if (IS_ERR(dev)) {
+		ret = PTR_ERR(dev);
+		goto out;
+	}
+	nkl = kzalloc_obj(*nkl, GFP_KERNEL_ACCOUNT);
+	if (!nkl) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	ret = netkit_link_init(nkl, &link_primer, attr, dev, prog);
+	if (ret) {
+		kfree(nkl);
+		goto out;
+	}
+	ret = netkit_link_prog_attach(&nkl->link,
+				      attr->link_create.flags,
+				      attr->link_create.netkit.relative_fd,
+				      attr->link_create.netkit.expected_revision);
+	if (ret) {
+		nkl->dev = NULL;
+		bpf_link_cleanup(&link_primer);
+		goto out;
+	}
+	ret = bpf_link_settle(&link_primer);
+out:
+	rtnl_unlock();
+	return ret;
+}
+
+static void netkit_release_all(struct net_device *dev)
+{
+	struct bpf_mprog_entry *entry;
+	struct bpf_tuple tuple = {};
+	struct bpf_mprog_fp *fp;
+	struct bpf_mprog_cp *cp;
+
+	entry = netkit_entry_fetch(dev, false);
+	if (!entry)
+		return;
+	netkit_entry_update(dev, NULL);
+	netkit_entry_sync();
+	bpf_mprog_foreach_tuple(entry, fp, cp, tuple) {
+		if (tuple.link)
+			netkit_link(tuple.link)->dev = NULL;
+		else
+			bpf_prog_put(tuple.prog);
+	}
+}
+
+static void netkit_uninit(struct net_device *dev)
+{
+	netkit_release_all(dev);
+	netkit_queue_unlease(dev);
+}
+
+static void netkit_del_link(struct net_device *dev, struct list_head *head)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct net_device *peer = rtnl_dereference(nk->peer);
+
+	RCU_INIT_POINTER(nk->peer, NULL);
+	unregister_netdevice_queue(dev, head);
+	if (peer) {
+		nk = netkit_priv(peer);
+		RCU_INIT_POINTER(nk->peer, NULL);
+		/* Guard against the peer already being in an unregister
+		 * list (e.g. same-namespace teardown where the peer is
+		 * in the caller's dev_kill_list). list_move_tail() on an
+		 * already-queued device would otherwise corrupt that
+		 * list's iteration. This situation can occur via netkit
+		 * notifier, hence guard against this scenario.
+		 */
+		if (!unregister_netdevice_queued(peer))
+			unregister_netdevice_queue(peer, head);
+	}
+}
+
+static int netkit_change_link(struct net_device *dev, struct nlattr *tb[],
+			      struct nlattr *data[],
+			      struct netlink_ext_ack *extack)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct net_device *peer = rtnl_dereference(nk->peer);
+	enum netkit_action policy;
+	struct nlattr *attr;
+	int err, i;
+	static const struct {
+		u32 attr;
+		char *name;
+	} fixed_params[] = {
+		{ IFLA_NETKIT_MODE,       "operating mode" },
+		{ IFLA_NETKIT_SCRUB,      "scrubbing" },
+		{ IFLA_NETKIT_PEER_SCRUB, "peer scrubbing" },
+		{ IFLA_NETKIT_PEER_INFO,  "peer info" },
+		{ IFLA_NETKIT_HEADROOM,   "headroom" },
+		{ IFLA_NETKIT_TAILROOM,   "tailroom" },
+		{ IFLA_NETKIT_PAIRING,    "pairing" },
+	};
+
+	if (!nk->primary) {
+		NL_SET_ERR_MSG(extack,
+			       "netkit link settings can be changed only through the primary device");
+		return -EACCES;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(fixed_params); i++) {
+		attr = data[fixed_params[i].attr];
+		if (attr) {
+			NL_SET_ERR_MSG_ATTR_FMT(extack, attr,
+						"netkit link %s cannot be changed after device creation",
+						fixed_params[i].name);
+			return -EACCES;
+		}
+	}
+
+	if (data[IFLA_NETKIT_POLICY]) {
+		err = -EOPNOTSUPP;
+		attr = data[IFLA_NETKIT_POLICY];
+		policy = nla_get_u32(attr);
+		if (nk->pair == NETKIT_DEVICE_PAIR)
+			err = netkit_check_policy(policy, attr, extack);
+		if (err)
+			return err;
+		WRITE_ONCE(nk->policy, policy);
+	}
+
+	if (data[IFLA_NETKIT_PEER_POLICY]) {
+		err = -EOPNOTSUPP;
+		attr = data[IFLA_NETKIT_PEER_POLICY];
+		policy = nla_get_u32(attr);
+		if (peer)
+			err = netkit_check_policy(policy, attr, extack);
+		if (err)
+			return err;
+		nk = netkit_priv(peer);
+		WRITE_ONCE(nk->policy, policy);
+	}
+
+	return 0;
+}
+
+static void netkit_check_lease_unregister(struct net_device *dev)
+{
+	LIST_HEAD(list_kill);
+	u32 q_idx;
+
+	if (READ_ONCE(dev->reg_state) != NETREG_UNREGISTERING ||
+	    !dev->dev.parent)
+		return;
+
+	netdev_lock_ops(dev);
+	for (q_idx = 0; q_idx < dev->real_num_rx_queues; q_idx++) {
+		struct net_device *tmp = dev;
+		struct netdev_rx_queue *rxq;
+		u32 tmp_q_idx = q_idx;
+
+		rxq = __netif_get_rx_queue_lease(&tmp, &tmp_q_idx,
+						 NETIF_PHYS_TO_VIRT);
+		if (rxq && tmp != dev &&
+		    tmp->netdev_ops == &netkit_netdev_ops) {
+			/* A single phys device can have multiple queues leased
+			 * to one netkit device. We can only queue that netkit
+			 * device once to the list_kill. Queues of that phys
+			 * device can be leased with different individual netkit
+			 * devices, hence we batch via list_kill.
+			 */
+			if (unregister_netdevice_queued(tmp))
+				continue;
+			netkit_del_link(tmp, &list_kill);
+		}
+	}
+	netdev_unlock_ops(dev);
+	unregister_netdevice_many(&list_kill);
+}
+
+static int netkit_notifier(struct notifier_block *this,
+			   unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+	if (event == NETDEV_UNREGISTER)
+		netkit_check_lease_unregister(dev);
+	return NOTIFY_DONE;
+}
+
+static size_t netkit_get_size(const struct net_device *dev)
+{
+	return nla_total_size(sizeof(u32)) + /* IFLA_NETKIT_POLICY */
+	       nla_total_size(sizeof(u32)) + /* IFLA_NETKIT_PEER_POLICY */
+	       nla_total_size(sizeof(u32)) + /* IFLA_NETKIT_SCRUB */
+	       nla_total_size(sizeof(u32)) + /* IFLA_NETKIT_PEER_SCRUB */
+	       nla_total_size(sizeof(u32)) + /* IFLA_NETKIT_MODE */
+	       nla_total_size(sizeof(u8))  + /* IFLA_NETKIT_PRIMARY */
+	       nla_total_size(sizeof(u16)) + /* IFLA_NETKIT_HEADROOM */
+	       nla_total_size(sizeof(u16)) + /* IFLA_NETKIT_TAILROOM */
+	       nla_total_size(sizeof(u32)) + /* IFLA_NETKIT_PAIRING */
+	       0;
+}
+
+static int netkit_fill_info(struct sk_buff *skb, const struct net_device *dev)
+{
+	struct netkit *nk = netkit_priv(dev);
+	struct net_device *peer = rtnl_dereference(nk->peer);
+
+	if (nla_put_u8(skb, IFLA_NETKIT_PRIMARY, nk->primary))
+		return -EMSGSIZE;
+	if (nla_put_u32(skb, IFLA_NETKIT_POLICY, nk->policy))
+		return -EMSGSIZE;
+	if (nla_put_u32(skb, IFLA_NETKIT_MODE, nk->mode))
+		return -EMSGSIZE;
+	if (nk->pair == NETKIT_DEVICE_PAIR &&
+	    nla_put_u32(skb, IFLA_NETKIT_SCRUB, nk->scrub))
+		return -EMSGSIZE;
+	if (nla_put_u16(skb, IFLA_NETKIT_HEADROOM, dev->needed_headroom))
+		return -EMSGSIZE;
+	if (nla_put_u16(skb, IFLA_NETKIT_TAILROOM, dev->needed_tailroom))
+		return -EMSGSIZE;
+	if (nla_put_u32(skb, IFLA_NETKIT_PAIRING, nk->pair))
+		return -EMSGSIZE;
+
+	if (peer) {
+		nk = netkit_priv(peer);
+		if (nla_put_u32(skb, IFLA_NETKIT_PEER_POLICY, nk->policy))
+			return -EMSGSIZE;
+		if (nla_put_u32(skb, IFLA_NETKIT_PEER_SCRUB, nk->scrub))
+			return -EMSGSIZE;
+	}
+
+	return 0;
+}
+
+static const struct nla_policy netkit_policy[IFLA_NETKIT_MAX + 1] = {
+	[IFLA_NETKIT_PEER_INFO]		= { .len = sizeof(struct ifinfomsg) },
+	[IFLA_NETKIT_MODE]		= NLA_POLICY_MAX(NLA_U32, NETKIT_L3),
+	[IFLA_NETKIT_POLICY]		= { .type = NLA_U32 },
+	[IFLA_NETKIT_PEER_POLICY]	= { .type = NLA_U32 },
+	[IFLA_NETKIT_HEADROOM]		= { .type = NLA_U16 },
+	[IFLA_NETKIT_TAILROOM]		= { .type = NLA_U16 },
+	[IFLA_NETKIT_SCRUB]		= NLA_POLICY_MAX(NLA_U32, NETKIT_SCRUB_DEFAULT),
+	[IFLA_NETKIT_PEER_SCRUB]	= NLA_POLICY_MAX(NLA_U32, NETKIT_SCRUB_DEFAULT),
+	[IFLA_NETKIT_PAIRING]		= NLA_POLICY_MAX(NLA_U32, NETKIT_DEVICE_SINGLE),
+	[IFLA_NETKIT_PRIMARY]		= { .type = NLA_REJECT,
+					    .reject_message = "Primary attribute is read-only" },
+};
+
+static struct rtnl_link_ops netkit_link_ops = {
+	.kind		= NETKIT_DRV_NAME,
+	.priv_size	= sizeof(struct netkit),
+	.alloc		= netkit_alloc,
+	.setup		= netkit_setup,
+	.newlink	= netkit_new_link,
+	.dellink	= netkit_del_link,
+	.changelink	= netkit_change_link,
+	.get_link_net	= netkit_get_link_net,
+	.get_size	= netkit_get_size,
+	.fill_info	= netkit_fill_info,
+	.policy		= netkit_policy,
+	.validate	= netkit_validate,
+	.peer_type	= IFLA_NETKIT_PEER_INFO,
+	.maxtype	= IFLA_NETKIT_MAX,
+};
+
+static struct notifier_block netkit_netdev_notifier = {
+	.notifier_call	= netkit_notifier,
+};
+
+static __init int netkit_mod_init(void)
+{
+	int ret;
+
+	BUILD_BUG_ON((int)NETKIT_NEXT != (int)TCX_NEXT ||
+		     (int)NETKIT_PASS != (int)TCX_PASS ||
+		     (int)NETKIT_DROP != (int)TCX_DROP ||
+		     (int)NETKIT_REDIRECT != (int)TCX_REDIRECT);
+
+	ret = rtnl_link_register(&netkit_link_ops);
+	if (ret)
+		return ret;
+	ret = register_netdevice_notifier(&netkit_netdev_notifier);
+	if (ret)
+		rtnl_link_unregister(&netkit_link_ops);
+	return ret;
+}
+
+static __exit void netkit_mod_exit(void)
+{
+	unregister_netdevice_notifier(&netkit_netdev_notifier);
+	rtnl_link_unregister(&netkit_link_ops);
+}
+
+module_init(netkit_mod_init);
+module_exit(netkit_mod_exit);
+
+MODULE_DESCRIPTION("BPF-programmable network device");
+MODULE_AUTHOR("Daniel Borkmann <daniel@iogearbox.net>");
+MODULE_AUTHOR("Nikolay Aleksandrov <razor@blackwall.org>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_RTNL_LINK(NETKIT_DRV_NAME);