// 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 <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 },
  };
  
  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),

  	.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 = 0;
  
  	if (tun_key->tun_flags & TUNNEL_KEY)
  		sum += nla_total_size(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 trunc_size, int in_ifindex, int out_ifindex,
  			   u32 sample_rate)
  {

  #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) +
  		   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 */

  #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 (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
  ");
  	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");