net/psample/psample.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * net/psample/psample.c - Netlink channel for packet sampling
  * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
  */

 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/skbuff.h>
 #include <linux/module.h>
 #include <linux/timekeeping.h>
 #include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/netlink.h>
 #include <net/genetlink.h>
 #include <net/psample.h>
 #include <linux/spinlock.h>
 #include <net/ip_tunnels.h>
 #include <net/dst_metadata.h>

 #define PSAMPLE_MAX_PACKET_SIZE 0xffff

 static LIST_HEAD(psample_groups_list);
 static DEFINE_SPINLOCK(psample_groups_lock);

 /* multicast groups */
 enum psample_nl_multicast_groups {
 	PSAMPLE_NL_MCGRP_CONFIG,
 	PSAMPLE_NL_MCGRP_SAMPLE,
 };

 static const struct genl_multicast_group psample_nl_mcgrps[] = {
 	[PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME },
 	[PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME,
 				      .flags = GENL_MCAST_CAP_NET_ADMIN, },
 };

 static struct genl_family psample_nl_family __ro_after_init;

 static int psample_group_nl_fill(struct sk_buff *msg,
 				 struct psample_group *group,
 				 enum psample_command cmd, u32 portid, u32 seq,
 				 int flags)
 {
 	void *hdr;
 	int ret;

 	hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd);
 	if (!hdr)
 		return -EMSGSIZE;

 	ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
 	if (ret < 0)
 		goto error;

 	ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount);
 	if (ret < 0)
 		goto error;

 	ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq);
 	if (ret < 0)
 		goto error;

 	genlmsg_end(msg, hdr);
 	return 0;

 error:
 	genlmsg_cancel(msg, hdr);
 	return -EMSGSIZE;
 }

 static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg,
 					   struct netlink_callback *cb)
 {
 	struct psample_group *group;
 	int start = cb->args[0];
 	int idx = 0;
 	int err;

 	spin_lock_bh(&psample_groups_lock);
 	list_for_each_entry(group, &psample_groups_list, list) {
 		if (!net_eq(group->net, sock_net(msg->sk)))
 			continue;
 		if (idx < start) {
 			idx++;
 			continue;
 		}
 		err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP,
 					    NETLINK_CB(cb->skb).portid,
 					    cb->nlh->nlmsg_seq, NLM_F_MULTI);
 		if (err)
 			break;
 		idx++;
 	}

 	spin_unlock_bh(&psample_groups_lock);
 	cb->args[0] = idx;
 	return msg->len;
 }

 static const struct genl_small_ops psample_nl_ops[] = {
 	{
 		.cmd = PSAMPLE_CMD_GET_GROUP,
 		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 		.dumpit = psample_nl_cmd_get_group_dumpit,
 		/* can be retrieved by unprivileged users */
 	}
 };

 static struct genl_family psample_nl_family __ro_after_init = {
 	.name		= PSAMPLE_GENL_NAME,
 	.version	= PSAMPLE_GENL_VERSION,
 	.maxattr	= PSAMPLE_ATTR_MAX,
 	.netnsok	= true,
 	.module		= THIS_MODULE,
 	.mcgrps		= psample_nl_mcgrps,
 	.small_ops	= psample_nl_ops,
 	.n_small_ops	= ARRAY_SIZE(psample_nl_ops),
 	.resv_start_op	= PSAMPLE_CMD_GET_GROUP + 1,
 	.n_mcgrps	= ARRAY_SIZE(psample_nl_mcgrps),
 };

 static void psample_group_notify(struct psample_group *group,
 				 enum psample_command cmd)
 {
 	struct sk_buff *msg;
 	int err;

 	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 	if (!msg)
 		return;

 	err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI);
 	if (!err)
 		genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0,
 					PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC);
 	else
 		nlmsg_free(msg);
 }

 static struct psample_group *psample_group_create(struct net *net,
 						  u32 group_num)
 {
 	struct psample_group *group;

 	group = kzalloc(sizeof(*group), GFP_ATOMIC);
 	if (!group)
 		return NULL;

 	group->net = net;
 	group->group_num = group_num;
 	list_add_tail(&group->list, &psample_groups_list);

 	psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP);
 	return group;
 }

 static void psample_group_destroy(struct psample_group *group)
 {
 	psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP);
 	list_del(&group->list);
 	kfree_rcu(group, rcu);
 }

 static struct psample_group *
 psample_group_lookup(struct net *net, u32 group_num)
 {
 	struct psample_group *group;

 	list_for_each_entry(group, &psample_groups_list, list)
 		if ((group->group_num == group_num) && (group->net == net))
 			return group;
 	return NULL;
 }

 struct psample_group *psample_group_get(struct net *net, u32 group_num)
 {
 	struct psample_group *group;

 	spin_lock_bh(&psample_groups_lock);

 	group = psample_group_lookup(net, group_num);
 	if (!group) {
 		group = psample_group_create(net, group_num);
 		if (!group)
 			goto out;
 	}
 	group->refcount++;

 out:
 	spin_unlock_bh(&psample_groups_lock);
 	return group;
 }
 EXPORT_SYMBOL_GPL(psample_group_get);

 void psample_group_take(struct psample_group *group)
 {
 	spin_lock_bh(&psample_groups_lock);
 	group->refcount++;
 	spin_unlock_bh(&psample_groups_lock);
 }
 EXPORT_SYMBOL_GPL(psample_group_take);

 void psample_group_put(struct psample_group *group)
 {
 	spin_lock_bh(&psample_groups_lock);

 	if (--group->refcount == 0)
 		psample_group_destroy(group);

 	spin_unlock_bh(&psample_groups_lock);
 }
 EXPORT_SYMBOL_GPL(psample_group_put);

 #ifdef CONFIG_INET
 static int __psample_ip_tun_to_nlattr(struct sk_buff *skb,
 			      struct ip_tunnel_info *tun_info)
 {
 	unsigned short tun_proto = ip_tunnel_info_af(tun_info);
 	const void *tun_opts = ip_tunnel_info_opts(tun_info);
 	const struct ip_tunnel_key *tun_key = &tun_info->key;
 	int tun_opts_len = tun_info->options_len;

 	if (tun_key->tun_flags & TUNNEL_KEY &&
 	    nla_put_be64(skb, PSAMPLE_TUNNEL_KEY_ATTR_ID, tun_key->tun_id,
 			 PSAMPLE_TUNNEL_KEY_ATTR_PAD))
 		return -EMSGSIZE;

 	if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE &&
 	    nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_INFO_BRIDGE))
 		return -EMSGSIZE;

 	switch (tun_proto) {
 	case AF_INET:
 		if (tun_key->u.ipv4.src &&
 		    nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_SRC,
 				    tun_key->u.ipv4.src))
 			return -EMSGSIZE;
 		if (tun_key->u.ipv4.dst &&
 		    nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_DST,
 				    tun_key->u.ipv4.dst))
 			return -EMSGSIZE;
 		break;
 	case AF_INET6:
 		if (!ipv6_addr_any(&tun_key->u.ipv6.src) &&
 		    nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_SRC,
 				     &tun_key->u.ipv6.src))
 			return -EMSGSIZE;
 		if (!ipv6_addr_any(&tun_key->u.ipv6.dst) &&
 		    nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_DST,
 				     &tun_key->u.ipv6.dst))
 			return -EMSGSIZE;
 		break;
 	}
 	if (tun_key->tos &&
 	    nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TOS, tun_key->tos))
 		return -EMSGSIZE;
 	if (nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TTL, tun_key->ttl))
 		return -EMSGSIZE;
 	if ((tun_key->tun_flags & TUNNEL_DONT_FRAGMENT) &&
 	    nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_DONT_FRAGMENT))
 		return -EMSGSIZE;
 	if ((tun_key->tun_flags & TUNNEL_CSUM) &&
 	    nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_CSUM))
 		return -EMSGSIZE;
 	if (tun_key->tp_src &&
 	    nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_SRC, tun_key->tp_src))
 		return -EMSGSIZE;
 	if (tun_key->tp_dst &&
 	    nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_DST, tun_key->tp_dst))
 		return -EMSGSIZE;
 	if ((tun_key->tun_flags & TUNNEL_OAM) &&
 	    nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_OAM))
 		return -EMSGSIZE;
 	if (tun_opts_len) {
 		if (tun_key->tun_flags & TUNNEL_GENEVE_OPT &&
 		    nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_GENEVE_OPTS,
 			    tun_opts_len, tun_opts))
 			return -EMSGSIZE;
 		else if (tun_key->tun_flags & TUNNEL_ERSPAN_OPT &&
 			 nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_ERSPAN_OPTS,
 				 tun_opts_len, tun_opts))
 			return -EMSGSIZE;
 	}

 	return 0;
 }

 static int psample_ip_tun_to_nlattr(struct sk_buff *skb,
 			    struct ip_tunnel_info *tun_info)
 {
 	struct nlattr *nla;
 	int err;

 	nla = nla_nest_start_noflag(skb, PSAMPLE_ATTR_TUNNEL);
 	if (!nla)
 		return -EMSGSIZE;

 	err = __psample_ip_tun_to_nlattr(skb, tun_info);
 	if (err) {
 		nla_nest_cancel(skb, nla);
 		return err;
 	}

 	nla_nest_end(skb, nla);

 	return 0;
 }

 static int psample_tunnel_meta_len(struct ip_tunnel_info *tun_info)
 {
 	unsigned short tun_proto = ip_tunnel_info_af(tun_info);
 	const struct ip_tunnel_key *tun_key = &tun_info->key;
 	int tun_opts_len = tun_info->options_len;
 	int sum = nla_total_size(0);	/* PSAMPLE_ATTR_TUNNEL */

 	if (tun_key->tun_flags & TUNNEL_KEY)
 		sum += nla_total_size_64bit(sizeof(u64));

 	if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE)
 		sum += nla_total_size(0);

 	switch (tun_proto) {
 	case AF_INET:
 		if (tun_key->u.ipv4.src)
 			sum += nla_total_size(sizeof(u32));
 		if (tun_key->u.ipv4.dst)
 			sum += nla_total_size(sizeof(u32));
 		break;
 	case AF_INET6:
 		if (!ipv6_addr_any(&tun_key->u.ipv6.src))
 			sum += nla_total_size(sizeof(struct in6_addr));
 		if (!ipv6_addr_any(&tun_key->u.ipv6.dst))
 			sum += nla_total_size(sizeof(struct in6_addr));
 		break;
 	}
 	if (tun_key->tos)
 		sum += nla_total_size(sizeof(u8));
 	sum += nla_total_size(sizeof(u8));	/* TTL */
 	if (tun_key->tun_flags & TUNNEL_DONT_FRAGMENT)
 		sum += nla_total_size(0);
 	if (tun_key->tun_flags & TUNNEL_CSUM)
 		sum += nla_total_size(0);
 	if (tun_key->tp_src)
 		sum += nla_total_size(sizeof(u16));
 	if (tun_key->tp_dst)
 		sum += nla_total_size(sizeof(u16));
 	if (tun_key->tun_flags & TUNNEL_OAM)
 		sum += nla_total_size(0);
 	if (tun_opts_len) {
 		if (tun_key->tun_flags & TUNNEL_GENEVE_OPT)
 			sum += nla_total_size(tun_opts_len);
 		else if (tun_key->tun_flags & TUNNEL_ERSPAN_OPT)
 			sum += nla_total_size(tun_opts_len);
 	}

 	return sum;
 }
 #endif

 void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
 			   u32 sample_rate, const struct psample_metadata *md)
 {
 	ktime_t tstamp = ktime_get_real();
 	int out_ifindex = md->out_ifindex;
 	int in_ifindex = md->in_ifindex;
 	u32 trunc_size = md->trunc_size;
 #ifdef CONFIG_INET
 	struct ip_tunnel_info *tun_info;
 #endif
 	struct sk_buff *nl_skb;
 	int data_len;
 	int meta_len;
 	void *data;
 	int ret;

 	meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) +
 		   (out_ifindex ? nla_total_size(sizeof(u16)) : 0) +
 		   (md->out_tc_valid ? nla_total_size(sizeof(u16)) : 0) +
 		   (md->out_tc_occ_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
 		   (md->latency_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
 		   nla_total_size(sizeof(u32)) +	/* sample_rate */
 		   nla_total_size(sizeof(u32)) +	/* orig_size */
 		   nla_total_size(sizeof(u32)) +	/* group_num */
 		   nla_total_size(sizeof(u32)) +	/* seq */
 		   nla_total_size_64bit(sizeof(u64)) +	/* timestamp */
 		   nla_total_size(sizeof(u16));		/* protocol */

 #ifdef CONFIG_INET
 	tun_info = skb_tunnel_info(skb);
 	if (tun_info)
 		meta_len += psample_tunnel_meta_len(tun_info);
 #endif

 	data_len = min(skb->len, trunc_size);
 	if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)
 		data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN
 			    - NLA_ALIGNTO;

 	nl_skb = genlmsg_new(meta_len + nla_total_size(data_len), GFP_ATOMIC);
 	if (unlikely(!nl_skb))
 		return;

 	data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0,
 			   PSAMPLE_CMD_SAMPLE);
 	if (unlikely(!data))
 		goto error;

 	if (in_ifindex) {
 		ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex);
 		if (unlikely(ret < 0))
 			goto error;
 	}

 	if (out_ifindex) {
 		ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex);
 		if (unlikely(ret < 0))
 			goto error;
 	}

 	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate);
 	if (unlikely(ret < 0))
 		goto error;

 	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len);
 	if (unlikely(ret < 0))
 		goto error;

 	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
 	if (unlikely(ret < 0))
 		goto error;

 	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++);
 	if (unlikely(ret < 0))
 		goto error;

 	if (md->out_tc_valid) {
 		ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OUT_TC, md->out_tc);
 		if (unlikely(ret < 0))
 			goto error;
 	}

 	if (md->out_tc_occ_valid) {
 		ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_OUT_TC_OCC,
 					md->out_tc_occ, PSAMPLE_ATTR_PAD);
 		if (unlikely(ret < 0))
 			goto error;
 	}

 	if (md->latency_valid) {
 		ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_LATENCY,
 					md->latency, PSAMPLE_ATTR_PAD);
 		if (unlikely(ret < 0))
 			goto error;
 	}

 	ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_TIMESTAMP,
 				ktime_to_ns(tstamp), PSAMPLE_ATTR_PAD);
 	if (unlikely(ret < 0))
 		goto error;

 	ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_PROTO,
 			  be16_to_cpu(skb->protocol));
 	if (unlikely(ret < 0))
 		goto error;

 	if (data_len) {
 		int nla_len = nla_total_size(data_len);
 		struct nlattr *nla;

 		nla = skb_put(nl_skb, nla_len);
 		nla->nla_type = PSAMPLE_ATTR_DATA;
 		nla->nla_len = nla_attr_size(data_len);

 		if (skb_copy_bits(skb, 0, nla_data(nla), data_len))
 			goto error;
 	}

 #ifdef CONFIG_INET
 	if (tun_info) {
 		ret = psample_ip_tun_to_nlattr(nl_skb, tun_info);
 		if (unlikely(ret < 0))
 			goto error;
 	}
 #endif

 	genlmsg_end(nl_skb, data);
 	genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,
 				PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC);

 	return;
 error:
 	pr_err_ratelimited("Could not create psample log message\n");
 	nlmsg_free(nl_skb);
 }
 EXPORT_SYMBOL_GPL(psample_sample_packet);

 static int __init psample_module_init(void)
 {
 	return genl_register_family(&psample_nl_family);
 }

 static void __exit psample_module_exit(void)
 {
 	genl_unregister_family(&psample_nl_family);
 }

 module_init(psample_module_init);
 module_exit(psample_module_exit);

 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 MODULE_DESCRIPTION("netlink channel for packet sampling");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* net/psample/psample.c - Netlink channel for packet sampling
	* Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
	*/

	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/skbuff.h>
	#include <linux/module.h>
	#include <linux/timekeeping.h>
	#include <net/net_namespace.h>
	#include <net/sock.h>
	#include <net/netlink.h>
	#include <net/genetlink.h>
	#include <net/psample.h>
	#include <linux/spinlock.h>
	#include <net/ip_tunnels.h>
	#include <net/dst_metadata.h>

	#define PSAMPLE_MAX_PACKET_SIZE 0xffff

	static LIST_HEAD(psample_groups_list);
	static DEFINE_SPINLOCK(psample_groups_lock);

	/* multicast groups */
	enum psample_nl_multicast_groups {
	PSAMPLE_NL_MCGRP_CONFIG,
	PSAMPLE_NL_MCGRP_SAMPLE,
	};

	static const struct genl_multicast_group psample_nl_mcgrps[] = {
	[PSAMPLE_NL_MCGRP_CONFIG] = { .name = PSAMPLE_NL_MCGRP_CONFIG_NAME },
	[PSAMPLE_NL_MCGRP_SAMPLE] = { .name = PSAMPLE_NL_MCGRP_SAMPLE_NAME,
	.flags = GENL_MCAST_CAP_NET_ADMIN, },
	};

	static struct genl_family psample_nl_family __ro_after_init;

	static int psample_group_nl_fill(struct sk_buff *msg,
	struct psample_group *group,
	enum psample_command cmd, u32 portid, u32 seq,
	int flags)
	{
	void *hdr;
	int ret;

	hdr = genlmsg_put(msg, portid, seq, &psample_nl_family, flags, cmd);
	if (!hdr)
	return -EMSGSIZE;

	ret = nla_put_u32(msg, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
	if (ret < 0)
	goto error;

	ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_REFCOUNT, group->refcount);
	if (ret < 0)
	goto error;

	ret = nla_put_u32(msg, PSAMPLE_ATTR_GROUP_SEQ, group->seq);
	if (ret < 0)
	goto error;

	genlmsg_end(msg, hdr);
	return 0;

	error:
	genlmsg_cancel(msg, hdr);
	return -EMSGSIZE;
	}

	static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg,
	struct netlink_callback *cb)
	{
	struct psample_group *group;
	int start = cb->args[0];
	int idx = 0;
	int err;

	spin_lock_bh(&psample_groups_lock);
	list_for_each_entry(group, &psample_groups_list, list) {
	if (!net_eq(group->net, sock_net(msg->sk)))
	continue;
	if (idx < start) {
	idx++;
	continue;
	}
	err = psample_group_nl_fill(msg, group, PSAMPLE_CMD_NEW_GROUP,
	NETLINK_CB(cb->skb).portid,
	cb->nlh->nlmsg_seq, NLM_F_MULTI);
	if (err)
	break;
	idx++;
	}

	spin_unlock_bh(&psample_groups_lock);
	cb->args[0] = idx;
	return msg->len;
	}

	static const struct genl_small_ops psample_nl_ops[] = {
	{
	.cmd = PSAMPLE_CMD_GET_GROUP,
	.validate = GENL_DONT_VALIDATE_STRICT \| GENL_DONT_VALIDATE_DUMP,
	.dumpit = psample_nl_cmd_get_group_dumpit,
	/* can be retrieved by unprivileged users */
	}
	};

	static struct genl_family psample_nl_family __ro_after_init = {
	.name = PSAMPLE_GENL_NAME,
	.version = PSAMPLE_GENL_VERSION,
	.maxattr = PSAMPLE_ATTR_MAX,
	.netnsok = true,
	.module = THIS_MODULE,
	.mcgrps = psample_nl_mcgrps,
	.small_ops = psample_nl_ops,
	.n_small_ops = ARRAY_SIZE(psample_nl_ops),
	.resv_start_op = PSAMPLE_CMD_GET_GROUP + 1,
	.n_mcgrps = ARRAY_SIZE(psample_nl_mcgrps),
	};

	static void psample_group_notify(struct psample_group *group,
	enum psample_command cmd)
	{
	struct sk_buff *msg;
	int err;

	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
	if (!msg)
	return;

	err = psample_group_nl_fill(msg, group, cmd, 0, 0, NLM_F_MULTI);
	if (!err)
	genlmsg_multicast_netns(&psample_nl_family, group->net, msg, 0,
	PSAMPLE_NL_MCGRP_CONFIG, GFP_ATOMIC);
	else
	nlmsg_free(msg);
	}

	static struct psample_group psample_group_create(struct net net,
	u32 group_num)
	{
	struct psample_group *group;

	group = kzalloc(sizeof(*group), GFP_ATOMIC);
	if (!group)
	return NULL;

	group->net = net;
	group->group_num = group_num;
	list_add_tail(&group->list, &psample_groups_list);

	psample_group_notify(group, PSAMPLE_CMD_NEW_GROUP);
	return group;
	}

	static void psample_group_destroy(struct psample_group *group)
	{
	psample_group_notify(group, PSAMPLE_CMD_DEL_GROUP);
	list_del(&group->list);
	kfree_rcu(group, rcu);
	}

	static struct psample_group *
	psample_group_lookup(struct net *net, u32 group_num)
	{
	struct psample_group *group;

	list_for_each_entry(group, &psample_groups_list, list)
	if ((group->group_num == group_num) && (group->net == net))
	return group;
	return NULL;
	}

	struct psample_group psample_group_get(struct net net, u32 group_num)
	{
	struct psample_group *group;

	spin_lock_bh(&psample_groups_lock);

	group = psample_group_lookup(net, group_num);
	if (!group) {
	group = psample_group_create(net, group_num);
	if (!group)
	goto out;
	}
	group->refcount++;

	out:
	spin_unlock_bh(&psample_groups_lock);
	return group;
	}
	EXPORT_SYMBOL_GPL(psample_group_get);

	void psample_group_take(struct psample_group *group)
	{
	spin_lock_bh(&psample_groups_lock);
	group->refcount++;
	spin_unlock_bh(&psample_groups_lock);
	}
	EXPORT_SYMBOL_GPL(psample_group_take);

	void psample_group_put(struct psample_group *group)
	{
	spin_lock_bh(&psample_groups_lock);

	if (--group->refcount == 0)
	psample_group_destroy(group);

	spin_unlock_bh(&psample_groups_lock);
	}
	EXPORT_SYMBOL_GPL(psample_group_put);

	#ifdef CONFIG_INET
	static int __psample_ip_tun_to_nlattr(struct sk_buff *skb,
	struct ip_tunnel_info *tun_info)
	{
	unsigned short tun_proto = ip_tunnel_info_af(tun_info);
	const void *tun_opts = ip_tunnel_info_opts(tun_info);
	const struct ip_tunnel_key *tun_key = &tun_info->key;
	int tun_opts_len = tun_info->options_len;

	if (tun_key->tun_flags & TUNNEL_KEY &&
	nla_put_be64(skb, PSAMPLE_TUNNEL_KEY_ATTR_ID, tun_key->tun_id,
	PSAMPLE_TUNNEL_KEY_ATTR_PAD))
	return -EMSGSIZE;

	if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE &&
	nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_INFO_BRIDGE))
	return -EMSGSIZE;

	switch (tun_proto) {
	case AF_INET:
	if (tun_key->u.ipv4.src &&
	nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_SRC,
	tun_key->u.ipv4.src))
	return -EMSGSIZE;
	if (tun_key->u.ipv4.dst &&
	nla_put_in_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV4_DST,
	tun_key->u.ipv4.dst))
	return -EMSGSIZE;
	break;
	case AF_INET6:
	if (!ipv6_addr_any(&tun_key->u.ipv6.src) &&
	nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_SRC,
	&tun_key->u.ipv6.src))
	return -EMSGSIZE;
	if (!ipv6_addr_any(&tun_key->u.ipv6.dst) &&
	nla_put_in6_addr(skb, PSAMPLE_TUNNEL_KEY_ATTR_IPV6_DST,
	&tun_key->u.ipv6.dst))
	return -EMSGSIZE;
	break;
	}
	if (tun_key->tos &&
	nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TOS, tun_key->tos))
	return -EMSGSIZE;
	if (nla_put_u8(skb, PSAMPLE_TUNNEL_KEY_ATTR_TTL, tun_key->ttl))
	return -EMSGSIZE;
	if ((tun_key->tun_flags & TUNNEL_DONT_FRAGMENT) &&
	nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_DONT_FRAGMENT))
	return -EMSGSIZE;
	if ((tun_key->tun_flags & TUNNEL_CSUM) &&
	nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_CSUM))
	return -EMSGSIZE;
	if (tun_key->tp_src &&
	nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_SRC, tun_key->tp_src))
	return -EMSGSIZE;
	if (tun_key->tp_dst &&
	nla_put_be16(skb, PSAMPLE_TUNNEL_KEY_ATTR_TP_DST, tun_key->tp_dst))
	return -EMSGSIZE;
	if ((tun_key->tun_flags & TUNNEL_OAM) &&
	nla_put_flag(skb, PSAMPLE_TUNNEL_KEY_ATTR_OAM))
	return -EMSGSIZE;
	if (tun_opts_len) {
	if (tun_key->tun_flags & TUNNEL_GENEVE_OPT &&
	nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_GENEVE_OPTS,
	tun_opts_len, tun_opts))
	return -EMSGSIZE;
	else if (tun_key->tun_flags & TUNNEL_ERSPAN_OPT &&
	nla_put(skb, PSAMPLE_TUNNEL_KEY_ATTR_ERSPAN_OPTS,
	tun_opts_len, tun_opts))
	return -EMSGSIZE;
	}

	return 0;
	}

	static int psample_ip_tun_to_nlattr(struct sk_buff *skb,
	struct ip_tunnel_info *tun_info)
	{
	struct nlattr *nla;
	int err;

	nla = nla_nest_start_noflag(skb, PSAMPLE_ATTR_TUNNEL);
	if (!nla)
	return -EMSGSIZE;

	err = __psample_ip_tun_to_nlattr(skb, tun_info);
	if (err) {
	nla_nest_cancel(skb, nla);
	return err;
	}

	nla_nest_end(skb, nla);

	return 0;
	}

	static int psample_tunnel_meta_len(struct ip_tunnel_info *tun_info)
	{
	unsigned short tun_proto = ip_tunnel_info_af(tun_info);
	const struct ip_tunnel_key *tun_key = &tun_info->key;
	int tun_opts_len = tun_info->options_len;
	int sum = nla_total_size(0); /* PSAMPLE_ATTR_TUNNEL */

	if (tun_key->tun_flags & TUNNEL_KEY)
	sum += nla_total_size_64bit(sizeof(u64));

	if (tun_info->mode & IP_TUNNEL_INFO_BRIDGE)
	sum += nla_total_size(0);

	switch (tun_proto) {
	case AF_INET:
	if (tun_key->u.ipv4.src)
	sum += nla_total_size(sizeof(u32));
	if (tun_key->u.ipv4.dst)
	sum += nla_total_size(sizeof(u32));
	break;
	case AF_INET6:
	if (!ipv6_addr_any(&tun_key->u.ipv6.src))
	sum += nla_total_size(sizeof(struct in6_addr));
	if (!ipv6_addr_any(&tun_key->u.ipv6.dst))
	sum += nla_total_size(sizeof(struct in6_addr));
	break;
	}
	if (tun_key->tos)
	sum += nla_total_size(sizeof(u8));
	sum += nla_total_size(sizeof(u8)); /* TTL */
	if (tun_key->tun_flags & TUNNEL_DONT_FRAGMENT)
	sum += nla_total_size(0);
	if (tun_key->tun_flags & TUNNEL_CSUM)
	sum += nla_total_size(0);
	if (tun_key->tp_src)
	sum += nla_total_size(sizeof(u16));
	if (tun_key->tp_dst)
	sum += nla_total_size(sizeof(u16));
	if (tun_key->tun_flags & TUNNEL_OAM)
	sum += nla_total_size(0);
	if (tun_opts_len) {
	if (tun_key->tun_flags & TUNNEL_GENEVE_OPT)
	sum += nla_total_size(tun_opts_len);
	else if (tun_key->tun_flags & TUNNEL_ERSPAN_OPT)
	sum += nla_total_size(tun_opts_len);
	}

	return sum;
	}
	#endif

	void psample_sample_packet(struct psample_group group, struct sk_buff skb,
	u32 sample_rate, const struct psample_metadata *md)
	{
	ktime_t tstamp = ktime_get_real();
	int out_ifindex = md->out_ifindex;
	int in_ifindex = md->in_ifindex;
	u32 trunc_size = md->trunc_size;
	#ifdef CONFIG_INET
	struct ip_tunnel_info *tun_info;
	#endif
	struct sk_buff *nl_skb;
	int data_len;
	int meta_len;
	void *data;
	int ret;

	meta_len = (in_ifindex ? nla_total_size(sizeof(u16)) : 0) +
	(out_ifindex ? nla_total_size(sizeof(u16)) : 0) +
	(md->out_tc_valid ? nla_total_size(sizeof(u16)) : 0) +
	(md->out_tc_occ_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
	(md->latency_valid ? nla_total_size_64bit(sizeof(u64)) : 0) +
	nla_total_size(sizeof(u32)) + /* sample_rate */
	nla_total_size(sizeof(u32)) + /* orig_size */
	nla_total_size(sizeof(u32)) + /* group_num */
	nla_total_size(sizeof(u32)) + /* seq */
	nla_total_size_64bit(sizeof(u64)) + /* timestamp */
	nla_total_size(sizeof(u16)); /* protocol */

	#ifdef CONFIG_INET
	tun_info = skb_tunnel_info(skb);
	if (tun_info)
	meta_len += psample_tunnel_meta_len(tun_info);
	#endif

	data_len = min(skb->len, trunc_size);
	if (meta_len + nla_total_size(data_len) > PSAMPLE_MAX_PACKET_SIZE)
	data_len = PSAMPLE_MAX_PACKET_SIZE - meta_len - NLA_HDRLEN
	- NLA_ALIGNTO;

	nl_skb = genlmsg_new(meta_len + nla_total_size(data_len), GFP_ATOMIC);
	if (unlikely(!nl_skb))
	return;

	data = genlmsg_put(nl_skb, 0, 0, &psample_nl_family, 0,
	PSAMPLE_CMD_SAMPLE);
	if (unlikely(!data))
	goto error;

	if (in_ifindex) {
	ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_IIFINDEX, in_ifindex);
	if (unlikely(ret < 0))
	goto error;
	}

	if (out_ifindex) {
	ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OIFINDEX, out_ifindex);
	if (unlikely(ret < 0))
	goto error;
	}

	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_RATE, sample_rate);
	if (unlikely(ret < 0))
	goto error;

	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_ORIGSIZE, skb->len);
	if (unlikely(ret < 0))
	goto error;

	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_SAMPLE_GROUP, group->group_num);
	if (unlikely(ret < 0))
	goto error;

	ret = nla_put_u32(nl_skb, PSAMPLE_ATTR_GROUP_SEQ, group->seq++);
	if (unlikely(ret < 0))
	goto error;

	if (md->out_tc_valid) {
	ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_OUT_TC, md->out_tc);
	if (unlikely(ret < 0))
	goto error;
	}

	if (md->out_tc_occ_valid) {
	ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_OUT_TC_OCC,
	md->out_tc_occ, PSAMPLE_ATTR_PAD);
	if (unlikely(ret < 0))
	goto error;
	}

	if (md->latency_valid) {
	ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_LATENCY,
	md->latency, PSAMPLE_ATTR_PAD);
	if (unlikely(ret < 0))
	goto error;
	}

	ret = nla_put_u64_64bit(nl_skb, PSAMPLE_ATTR_TIMESTAMP,
	ktime_to_ns(tstamp), PSAMPLE_ATTR_PAD);
	if (unlikely(ret < 0))
	goto error;

	ret = nla_put_u16(nl_skb, PSAMPLE_ATTR_PROTO,
	be16_to_cpu(skb->protocol));
	if (unlikely(ret < 0))
	goto error;

	if (data_len) {
	int nla_len = nla_total_size(data_len);
	struct nlattr *nla;

	nla = skb_put(nl_skb, nla_len);
	nla->nla_type = PSAMPLE_ATTR_DATA;
	nla->nla_len = nla_attr_size(data_len);

	if (skb_copy_bits(skb, 0, nla_data(nla), data_len))
	goto error;
	}

	#ifdef CONFIG_INET
	if (tun_info) {
	ret = psample_ip_tun_to_nlattr(nl_skb, tun_info);
	if (unlikely(ret < 0))
	goto error;
	}
	#endif

	genlmsg_end(nl_skb, data);
	genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,
	PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC);

	return;
	error:
	pr_err_ratelimited("Could not create psample log message\n");
	nlmsg_free(nl_skb);
	}
	EXPORT_SYMBOL_GPL(psample_sample_packet);

	static int __init psample_module_init(void)
	{
	return genl_register_family(&psample_nl_family);
	}

	static void __exit psample_module_exit(void)
	{
	genl_unregister_family(&psample_nl_family);
	}

	module_init(psample_module_init);
	module_exit(psample_module_exit);

	MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
	MODULE_DESCRIPTION("netlink channel for packet sampling");
	MODULE_LICENSE("GPL v2");