net/sched/act_ct.c

// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
/* -
 * net/sched/act_ct.c  Connection Tracking action
 *
 * Authors:   Paul Blakey <paulb@mellanox.com>
 *            Yossi Kuperman <yossiku@mellanox.com>
 *            Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/pkt_cls.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/rhashtable.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <net/act_api.h>
#include <net/ip.h>
#include <net/ipv6_frag.h>
#include <uapi/linux/tc_act/tc_ct.h>
#include <net/tc_act/tc_ct.h>

#include <net/netfilter/nf_flow_table.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#include <uapi/linux/netfilter/nf_nat.h>

static struct workqueue_struct *act_ct_wq;
static struct rhashtable zones_ht;
static DEFINE_SPINLOCK(zones_lock);

struct tcf_ct_flow_table {
	struct rhash_head node; /* In zones tables */

	struct rcu_work rwork;
	struct nf_flowtable nf_ft;
	u16 zone;
	u32 ref;

	bool dying;
};

static const struct rhashtable_params zones_params = {
	.head_offset = offsetof(struct tcf_ct_flow_table, node),
	.key_offset = offsetof(struct tcf_ct_flow_table, zone),
	.key_len = sizeof_field(struct tcf_ct_flow_table, zone),
	.automatic_shrinking = true,
};

static struct nf_flowtable_type flowtable_ct = {
	.owner		= THIS_MODULE,
};

static int tcf_ct_flow_table_get(struct tcf_ct_params *params)
{
	struct tcf_ct_flow_table *ct_ft;
	int err = -ENOMEM;

	spin_lock_bh(&zones_lock);
	ct_ft = rhashtable_lookup_fast(&zones_ht, &params->zone, zones_params);
	if (ct_ft)
		goto take_ref;

	ct_ft = kzalloc(sizeof(*ct_ft), GFP_ATOMIC);
	if (!ct_ft)
		goto err_alloc;

	ct_ft->zone = params->zone;
	err = rhashtable_insert_fast(&zones_ht, &ct_ft->node, zones_params);
	if (err)
		goto err_insert;

	ct_ft->nf_ft.type = &flowtable_ct;
	err = nf_flow_table_init(&ct_ft->nf_ft);
	if (err)
		goto err_init;

	__module_get(THIS_MODULE);
take_ref:
	params->ct_ft = ct_ft;
	ct_ft->ref++;
	spin_unlock_bh(&zones_lock);

	return 0;

err_init:
	rhashtable_remove_fast(&zones_ht, &ct_ft->node, zones_params);
err_insert:
	kfree(ct_ft);
err_alloc:
	spin_unlock_bh(&zones_lock);
	return err;
}

static void tcf_ct_flow_table_cleanup_work(struct work_struct *work)
{
	struct tcf_ct_flow_table *ct_ft;

	ct_ft = container_of(to_rcu_work(work), struct tcf_ct_flow_table,
			     rwork);
	nf_flow_table_free(&ct_ft->nf_ft);
	kfree(ct_ft);

	module_put(THIS_MODULE);
}

static void tcf_ct_flow_table_put(struct tcf_ct_params *params)
{
	struct tcf_ct_flow_table *ct_ft = params->ct_ft;

	spin_lock_bh(&zones_lock);
	if (--params->ct_ft->ref == 0) {
		rhashtable_remove_fast(&zones_ht, &ct_ft->node, zones_params);
		INIT_RCU_WORK(&ct_ft->rwork, tcf_ct_flow_table_cleanup_work);
		queue_rcu_work(act_ct_wq, &ct_ft->rwork);
	}
	spin_unlock_bh(&zones_lock);
}

static void tcf_ct_flow_table_add(struct tcf_ct_flow_table *ct_ft,
				  struct nf_conn *ct,
				  bool tcp)
{
	struct flow_offload *entry;
	int err;

	if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
		return;

	entry = flow_offload_alloc(ct);
	if (!entry) {
		WARN_ON_ONCE(1);
		goto err_alloc;
	}

	if (tcp) {
		ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
		ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
	}

	err = flow_offload_add(&ct_ft->nf_ft, entry);
	if (err)
		goto err_add;

	return;

err_add:
	flow_offload_free(entry);
err_alloc:
	clear_bit(IPS_OFFLOAD_BIT, &ct->status);
}

static void tcf_ct_flow_table_process_conn(struct tcf_ct_flow_table *ct_ft,
					   struct nf_conn *ct,
					   enum ip_conntrack_info ctinfo)
{
	bool tcp = false;

	if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
		return;

	switch (nf_ct_protonum(ct)) {
	case IPPROTO_TCP:
		tcp = true;
		if (ct->proto.tcp.state != TCP_CONNTRACK_ESTABLISHED)
			return;
		break;
	case IPPROTO_UDP:
		break;
	default:
		return;
	}

	if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
	    ct->status & IPS_SEQ_ADJUST)
		return;

	tcf_ct_flow_table_add(ct_ft, ct, tcp);
}

static bool
tcf_ct_flow_table_fill_tuple_ipv4(struct sk_buff *skb,
				  struct flow_offload_tuple *tuple)
{
	struct flow_ports *ports;
	unsigned int thoff;
	struct iphdr *iph;

	if (!pskb_may_pull(skb, sizeof(*iph)))
		return false;

	iph = ip_hdr(skb);
	thoff = iph->ihl * 4;

	if (ip_is_fragment(iph) ||
	    unlikely(thoff != sizeof(struct iphdr)))
		return false;

	if (iph->protocol != IPPROTO_TCP &&
	    iph->protocol != IPPROTO_UDP)
		return false;

	if (iph->ttl <= 1)
		return false;

	if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
		return false;

	ports = (struct flow_ports *)(skb_network_header(skb) + thoff);

	tuple->src_v4.s_addr = iph->saddr;
	tuple->dst_v4.s_addr = iph->daddr;
	tuple->src_port = ports->source;
	tuple->dst_port = ports->dest;
	tuple->l3proto = AF_INET;
	tuple->l4proto = iph->protocol;

	return true;
}

static bool
tcf_ct_flow_table_fill_tuple_ipv6(struct sk_buff *skb,
				  struct flow_offload_tuple *tuple)
{
	struct flow_ports *ports;
	struct ipv6hdr *ip6h;
	unsigned int thoff;

	if (!pskb_may_pull(skb, sizeof(*ip6h)))
		return false;

	ip6h = ipv6_hdr(skb);

	if (ip6h->nexthdr != IPPROTO_TCP &&
	    ip6h->nexthdr != IPPROTO_UDP)
		return false;

	if (ip6h->hop_limit <= 1)
		return false;

	thoff = sizeof(*ip6h);
	if (!pskb_may_pull(skb, thoff + sizeof(*ports)))
		return false;

	ports = (struct flow_ports *)(skb_network_header(skb) + thoff);

	tuple->src_v6 = ip6h->saddr;
	tuple->dst_v6 = ip6h->daddr;
	tuple->src_port = ports->source;
	tuple->dst_port = ports->dest;
	tuple->l3proto = AF_INET6;
	tuple->l4proto = ip6h->nexthdr;

	return true;
}

static bool tcf_ct_flow_table_check_tcp(struct flow_offload *flow,
					struct sk_buff *skb,
					unsigned int thoff)
{
	struct tcphdr *tcph;

	if (!pskb_may_pull(skb, thoff + sizeof(*tcph)))
		return false;

	tcph = (void *)(skb_network_header(skb) + thoff);
	if (unlikely(tcph->fin || tcph->rst)) {
		flow_offload_teardown(flow);
		return false;
	}

	return true;
}

static bool tcf_ct_flow_table_lookup(struct tcf_ct_params *p,
				     struct sk_buff *skb,
				     u8 family)
{
	struct nf_flowtable *nf_ft = &p->ct_ft->nf_ft;
	struct flow_offload_tuple_rhash *tuplehash;
	struct flow_offload_tuple tuple = {};
	enum ip_conntrack_info ctinfo;
	struct flow_offload *flow;
	struct nf_conn *ct;
	unsigned int thoff;
	int ip_proto;
	u8 dir;

	/* Previously seen or loopback */
	ct = nf_ct_get(skb, &ctinfo);
	if ((ct && !nf_ct_is_template(ct)) || ctinfo == IP_CT_UNTRACKED)
		return false;

	switch (family) {
	case NFPROTO_IPV4:
		if (!tcf_ct_flow_table_fill_tuple_ipv4(skb, &tuple))
			return false;
		break;
	case NFPROTO_IPV6:
		if (!tcf_ct_flow_table_fill_tuple_ipv6(skb, &tuple))
			return false;
		break;
	default:
		return false;
	}

	tuplehash = flow_offload_lookup(nf_ft, &tuple);
	if (!tuplehash)
		return false;

	dir = tuplehash->tuple.dir;
	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
	ct = flow->ct;

	ctinfo = dir == FLOW_OFFLOAD_DIR_ORIGINAL ? IP_CT_ESTABLISHED :
						    IP_CT_ESTABLISHED_REPLY;

	thoff = ip_hdr(skb)->ihl * 4;
	ip_proto = ip_hdr(skb)->protocol;
	if (ip_proto == IPPROTO_TCP &&
	    !tcf_ct_flow_table_check_tcp(flow, skb, thoff))
		return false;

	nf_conntrack_get(&ct->ct_general);
	nf_ct_set(skb, ct, ctinfo);

	return true;
}

static int tcf_ct_flow_tables_init(void)
{
	return rhashtable_init(&zones_ht, &zones_params);
}

static void tcf_ct_flow_tables_uninit(void)
{
	rhashtable_destroy(&zones_ht);
}

static struct tc_action_ops act_ct_ops;
static unsigned int ct_net_id;

struct tc_ct_action_net {
	struct tc_action_net tn; /* Must be first */
	bool labels;
};

/* Determine whether skb->_nfct is equal to the result of conntrack lookup. */
static bool tcf_ct_skb_nfct_cached(struct net *net, struct sk_buff *skb,
				   u16 zone_id, bool force)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct;

	ct = nf_ct_get(skb, &ctinfo);
	if (!ct)
		return false;
	if (!net_eq(net, read_pnet(&ct->ct_net)))
		return false;
	if (nf_ct_zone(ct)->id != zone_id)
		return false;

	/* Force conntrack entry direction. */
	if (force && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
		if (nf_ct_is_confirmed(ct))
			nf_ct_kill(ct);

		nf_conntrack_put(&ct->ct_general);
		nf_ct_set(skb, NULL, IP_CT_UNTRACKED);

		return false;
	}

	return true;
}

/* Trim the skb to the length specified by the IP/IPv6 header,
 * removing any trailing lower-layer padding. This prepares the skb
 * for higher-layer processing that assumes skb->len excludes padding
 * (such as nf_ip_checksum). The caller needs to pull the skb to the
 * network header, and ensure ip_hdr/ipv6_hdr points to valid data.
 */
static int tcf_ct_skb_network_trim(struct sk_buff *skb, int family)
{
	unsigned int len;
	int err;

	switch (family) {
	case NFPROTO_IPV4:
		len = ntohs(ip_hdr(skb)->tot_len);
		break;
	case NFPROTO_IPV6:
		len = sizeof(struct ipv6hdr)
			+ ntohs(ipv6_hdr(skb)->payload_len);
		break;
	default:
		len = skb->len;
	}

	err = pskb_trim_rcsum(skb, len);

	return err;
}

static u8 tcf_ct_skb_nf_family(struct sk_buff *skb)
{
	u8 family = NFPROTO_UNSPEC;

	switch (skb->protocol) {
	case htons(ETH_P_IP):
		family = NFPROTO_IPV4;
		break;
	case htons(ETH_P_IPV6):
		family = NFPROTO_IPV6;
		break;
	default:
		break;
	}

	return family;
}

static int tcf_ct_ipv4_is_fragment(struct sk_buff *skb, bool *frag)
{
	unsigned int len;

	len =  skb_network_offset(skb) + sizeof(struct iphdr);
	if (unlikely(skb->len < len))
		return -EINVAL;
	if (unlikely(!pskb_may_pull(skb, len)))
		return -ENOMEM;

	*frag = ip_is_fragment(ip_hdr(skb));
	return 0;
}

static int tcf_ct_ipv6_is_fragment(struct sk_buff *skb, bool *frag)
{
	unsigned int flags = 0, len, payload_ofs = 0;
	unsigned short frag_off;
	int nexthdr;

	len =  skb_network_offset(skb) + sizeof(struct ipv6hdr);
	if (unlikely(skb->len < len))
		return -EINVAL;
	if (unlikely(!pskb_may_pull(skb, len)))
		return -ENOMEM;

	nexthdr = ipv6_find_hdr(skb, &payload_ofs, -1, &frag_off, &flags);
	if (unlikely(nexthdr < 0))
		return -EPROTO;

	*frag = flags & IP6_FH_F_FRAG;
	return 0;
}

static int tcf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
				   u8 family, u16 zone)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct;
	int err = 0;
	bool frag;

	/* Previously seen (loopback)? Ignore. */
	ct = nf_ct_get(skb, &ctinfo);
	if ((ct && !nf_ct_is_template(ct)) || ctinfo == IP_CT_UNTRACKED)
		return 0;

	if (family == NFPROTO_IPV4)
		err = tcf_ct_ipv4_is_fragment(skb, &frag);
	else
		err = tcf_ct_ipv6_is_fragment(skb, &frag);
	if (err || !frag)
		return err;

	skb_get(skb);

	if (family == NFPROTO_IPV4) {
		enum ip_defrag_users user = IP_DEFRAG_CONNTRACK_IN + zone;

		memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
		local_bh_disable();
		err = ip_defrag(net, skb, user);
		local_bh_enable();
		if (err && err != -EINPROGRESS)
			goto out_free;
	} else { /* NFPROTO_IPV6 */
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
		enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;

		memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
		err = nf_ct_frag6_gather(net, skb, user);
		if (err && err != -EINPROGRESS)
			goto out_free;
#else
		err = -EOPNOTSUPP;
		goto out_free;
#endif
	}

	skb_clear_hash(skb);
	skb->ignore_df = 1;
	return err;

out_free:
	kfree_skb(skb);
	return err;
}

static void tcf_ct_params_free(struct rcu_head *head)
{
	struct tcf_ct_params *params = container_of(head,
						    struct tcf_ct_params, rcu);

	tcf_ct_flow_table_put(params);

	if (params->tmpl)
		nf_conntrack_put(&params->tmpl->ct_general);
	kfree(params);
}

#if IS_ENABLED(CONFIG_NF_NAT)
/* Modelled after nf_nat_ipv[46]_fn().
 * range is only used for new, uninitialized NAT state.
 * Returns either NF_ACCEPT or NF_DROP.
 */
static int ct_nat_execute(struct sk_buff *skb, struct nf_conn *ct,
			  enum ip_conntrack_info ctinfo,
			  const struct nf_nat_range2 *range,
			  enum nf_nat_manip_type maniptype)
{
	int hooknum, err = NF_ACCEPT;

	/* See HOOK2MANIP(). */
	if (maniptype == NF_NAT_MANIP_SRC)
		hooknum = NF_INET_LOCAL_IN; /* Source NAT */
	else
		hooknum = NF_INET_LOCAL_OUT; /* Destination NAT */

	switch (ctinfo) {
	case IP_CT_RELATED:
	case IP_CT_RELATED_REPLY:
		if (skb->protocol == htons(ETH_P_IP) &&
		    ip_hdr(skb)->protocol == IPPROTO_ICMP) {
			if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
							   hooknum))
				err = NF_DROP;
			goto out;
		} else if (IS_ENABLED(CONFIG_IPV6) &&
			   skb->protocol == htons(ETH_P_IPV6)) {
			__be16 frag_off;
			u8 nexthdr = ipv6_hdr(skb)->nexthdr;
			int hdrlen = ipv6_skip_exthdr(skb,
						      sizeof(struct ipv6hdr),
						      &nexthdr, &frag_off);

			if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
				if (!nf_nat_icmpv6_reply_translation(skb, ct,
								     ctinfo,
								     hooknum,
								     hdrlen))
					err = NF_DROP;
				goto out;
			}
		}
		/* Non-ICMP, fall thru to initialize if needed. */
		/* fall through */
	case IP_CT_NEW:
		/* Seen it before?  This can happen for loopback, retrans,
		 * or local packets.
		 */
		if (!nf_nat_initialized(ct, maniptype)) {
			/* Initialize according to the NAT action. */
			err = (range && range->flags & NF_NAT_RANGE_MAP_IPS)
				/* Action is set up to establish a new
				 * mapping.
				 */
				? nf_nat_setup_info(ct, range, maniptype)
				: nf_nat_alloc_null_binding(ct, hooknum);
			if (err != NF_ACCEPT)
				goto out;
		}
		break;

	case IP_CT_ESTABLISHED:
	case IP_CT_ESTABLISHED_REPLY:
		break;

	default:
		err = NF_DROP;
		goto out;
	}

	err = nf_nat_packet(ct, ctinfo, hooknum, skb);
out:
	return err;
}
#endif /* CONFIG_NF_NAT */

static void tcf_ct_act_set_mark(struct nf_conn *ct, u32 mark, u32 mask)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)
	u32 new_mark;

	if (!mask)
		return;

	new_mark = mark | (ct->mark & ~(mask));
	if (ct->mark != new_mark) {
		ct->mark = new_mark;
		if (nf_ct_is_confirmed(ct))
			nf_conntrack_event_cache(IPCT_MARK, ct);
	}
#endif
}

static void tcf_ct_act_set_labels(struct nf_conn *ct,
				  u32 *labels,
				  u32 *labels_m)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS)
	size_t labels_sz = sizeof_field(struct tcf_ct_params, labels);

	if (!memchr_inv(labels_m, 0, labels_sz))
		return;

	nf_connlabels_replace(ct, labels, labels_m, 4);
#endif
}

static int tcf_ct_act_nat(struct sk_buff *skb,
			  struct nf_conn *ct,
			  enum ip_conntrack_info ctinfo,
			  int ct_action,
			  struct nf_nat_range2 *range,
			  bool commit)
{
#if IS_ENABLED(CONFIG_NF_NAT)
	int err;
	enum nf_nat_manip_type maniptype;

	if (!(ct_action & TCA_CT_ACT_NAT))
		return NF_ACCEPT;

	/* Add NAT extension if not confirmed yet. */
	if (!nf_ct_is_confirmed(ct) && !nf_ct_nat_ext_add(ct))
		return NF_DROP;   /* Can't NAT. */

	if (ctinfo != IP_CT_NEW && (ct->status & IPS_NAT_MASK) &&
	    (ctinfo != IP_CT_RELATED || commit)) {
		/* NAT an established or related connection like before. */
		if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY)
			/* This is the REPLY direction for a connection
			 * for which NAT was applied in the forward
			 * direction.  Do the reverse NAT.
			 */
			maniptype = ct->status & IPS_SRC_NAT
				? NF_NAT_MANIP_DST : NF_NAT_MANIP_SRC;
		else
			maniptype = ct->status & IPS_SRC_NAT
				? NF_NAT_MANIP_SRC : NF_NAT_MANIP_DST;
	} else if (ct_action & TCA_CT_ACT_NAT_SRC) {
		maniptype = NF_NAT_MANIP_SRC;
	} else if (ct_action & TCA_CT_ACT_NAT_DST) {
		maniptype = NF_NAT_MANIP_DST;
	} else {
		return NF_ACCEPT;
	}

	err = ct_nat_execute(skb, ct, ctinfo, range, maniptype);
	if (err == NF_ACCEPT &&
	    ct->status & IPS_SRC_NAT && ct->status & IPS_DST_NAT) {
		if (maniptype == NF_NAT_MANIP_SRC)
			maniptype = NF_NAT_MANIP_DST;
		else
			maniptype = NF_NAT_MANIP_SRC;

		err = ct_nat_execute(skb, ct, ctinfo, range, maniptype);
	}
	return err;
#else
	return NF_ACCEPT;
#endif
}

static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
		      struct tcf_result *res)
{
	struct net *net = dev_net(skb->dev);
	bool cached, commit, clear, force;
	enum ip_conntrack_info ctinfo;
	struct tcf_ct *c = to_ct(a);
	struct nf_conn *tmpl = NULL;
	struct nf_hook_state state;
	int nh_ofs, err, retval;
	struct tcf_ct_params *p;
	bool skip_add = false;
	struct nf_conn *ct;
	u8 family;

	p = rcu_dereference_bh(c->params);

	retval = READ_ONCE(c->tcf_action);
	commit = p->ct_action & TCA_CT_ACT_COMMIT;
	clear = p->ct_action & TCA_CT_ACT_CLEAR;
	force = p->ct_action & TCA_CT_ACT_FORCE;
	tmpl = p->tmpl;

	if (clear) {
		ct = nf_ct_get(skb, &ctinfo);
		if (ct) {
			nf_conntrack_put(&ct->ct_general);
			nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
		}

		goto out;
	}

	family = tcf_ct_skb_nf_family(skb);
	if (family == NFPROTO_UNSPEC)
		goto drop;

	/* The conntrack module expects to be working at L3.
	 * We also try to pull the IPv4/6 header to linear area
	 */
	nh_ofs = skb_network_offset(skb);
	skb_pull_rcsum(skb, nh_ofs);
	err = tcf_ct_handle_fragments(net, skb, family, p->zone);
	if (err == -EINPROGRESS) {
		retval = TC_ACT_STOLEN;
		goto out;
	}
	if (err)
		goto drop;

	err = tcf_ct_skb_network_trim(skb, family);
	if (err)
		goto drop;

	/* If we are recirculating packets to match on ct fields and
	 * committing with a separate ct action, then we don't need to
	 * actually run the packet through conntrack twice unless it's for a
	 * different zone.
	 */
	cached = tcf_ct_skb_nfct_cached(net, skb, p->zone, force);
	if (!cached) {
		if (!commit && tcf_ct_flow_table_lookup(p, skb, family)) {
			skip_add = true;
			goto do_nat;
		}

		/* Associate skb with specified zone. */
		if (tmpl) {
			ct = nf_ct_get(skb, &ctinfo);
			if (skb_nfct(skb))
				nf_conntrack_put(skb_nfct(skb));
			nf_conntrack_get(&tmpl->ct_general);
			nf_ct_set(skb, tmpl, IP_CT_NEW);
		}

		state.hook = NF_INET_PRE_ROUTING;
		state.net = net;
		state.pf = family;
		err = nf_conntrack_in(skb, &state);
		if (err != NF_ACCEPT)
			goto out_push;
	}

do_nat:
	ct = nf_ct_get(skb, &ctinfo);
	if (!ct)
		goto out_push;
	nf_ct_deliver_cached_events(ct);

	err = tcf_ct_act_nat(skb, ct, ctinfo, p->ct_action, &p->range, commit);
	if (err != NF_ACCEPT)
		goto drop;

	if (commit) {
		tcf_ct_act_set_mark(ct, p->mark, p->mark_mask);
		tcf_ct_act_set_labels(ct, p->labels, p->labels_mask);

		/* This will take care of sending queued events
		 * even if the connection is already confirmed.
		 */
		nf_conntrack_confirm(skb);
	} else if (!skip_add) {
		tcf_ct_flow_table_process_conn(p->ct_ft, ct, ctinfo);
	}

out_push:
	skb_push_rcsum(skb, nh_ofs);

out:
	tcf_action_update_bstats(&c->common, skb);
	return retval;

drop:
	tcf_action_inc_drop_qstats(&c->common);
	return TC_ACT_SHOT;
}

static const struct nla_policy ct_policy[TCA_CT_MAX + 1] = {
	[TCA_CT_ACTION] = { .type = NLA_U16 },
	[TCA_CT_PARMS] = { .type = NLA_EXACT_LEN, .len = sizeof(struct tc_ct) },
	[TCA_CT_ZONE] = { .type = NLA_U16 },
	[TCA_CT_MARK] = { .type = NLA_U32 },
	[TCA_CT_MARK_MASK] = { .type = NLA_U32 },
	[TCA_CT_LABELS] = { .type = NLA_BINARY,
			    .len = 128 / BITS_PER_BYTE },
	[TCA_CT_LABELS_MASK] = { .type = NLA_BINARY,
				 .len = 128 / BITS_PER_BYTE },
	[TCA_CT_NAT_IPV4_MIN] = { .type = NLA_U32 },
	[TCA_CT_NAT_IPV4_MAX] = { .type = NLA_U32 },
	[TCA_CT_NAT_IPV6_MIN] = { .type = NLA_EXACT_LEN,
				  .len = sizeof(struct in6_addr) },
	[TCA_CT_NAT_IPV6_MAX] = { .type = NLA_EXACT_LEN,
				   .len = sizeof(struct in6_addr) },
	[TCA_CT_NAT_PORT_MIN] = { .type = NLA_U16 },
	[TCA_CT_NAT_PORT_MAX] = { .type = NLA_U16 },
};

static int tcf_ct_fill_params_nat(struct tcf_ct_params *p,
				  struct tc_ct *parm,
				  struct nlattr **tb,
				  struct netlink_ext_ack *extack)
{
	struct nf_nat_range2 *range;

	if (!(p->ct_action & TCA_CT_ACT_NAT))
		return 0;

	if (!IS_ENABLED(CONFIG_NF_NAT)) {
		NL_SET_ERR_MSG_MOD(extack, "Netfilter nat isn't enabled in kernel");
		return -EOPNOTSUPP;
	}

	if (!(p->ct_action & (TCA_CT_ACT_NAT_SRC | TCA_CT_ACT_NAT_DST)))
		return 0;

	if ((p->ct_action & TCA_CT_ACT_NAT_SRC) &&
	    (p->ct_action & TCA_CT_ACT_NAT_DST)) {
		NL_SET_ERR_MSG_MOD(extack, "dnat and snat can't be enabled at the same time");
		return -EOPNOTSUPP;
	}

	range = &p->range;
	if (tb[TCA_CT_NAT_IPV4_MIN]) {
		struct nlattr *max_attr = tb[TCA_CT_NAT_IPV4_MAX];

		p->ipv4_range = true;
		range->flags |= NF_NAT_RANGE_MAP_IPS;
		range->min_addr.ip =
			nla_get_in_addr(tb[TCA_CT_NAT_IPV4_MIN]);

		range->max_addr.ip = max_attr ?
				     nla_get_in_addr(max_attr) :
				     range->min_addr.ip;
	} else if (tb[TCA_CT_NAT_IPV6_MIN]) {
		struct nlattr *max_attr = tb[TCA_CT_NAT_IPV6_MAX];

		p->ipv4_range = false;
		range->flags |= NF_NAT_RANGE_MAP_IPS;
		range->min_addr.in6 =
			nla_get_in6_addr(tb[TCA_CT_NAT_IPV6_MIN]);

		range->max_addr.in6 = max_attr ?
				      nla_get_in6_addr(max_attr) :
				      range->min_addr.in6;
	}

	if (tb[TCA_CT_NAT_PORT_MIN]) {
		range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
		range->min_proto.all = nla_get_be16(tb[TCA_CT_NAT_PORT_MIN]);

		range->max_proto.all = tb[TCA_CT_NAT_PORT_MAX] ?
				       nla_get_be16(tb[TCA_CT_NAT_PORT_MAX]) :
				       range->min_proto.all;
	}

	return 0;
}

static void tcf_ct_set_key_val(struct nlattr **tb,
			       void *val, int val_type,
			       void *mask, int mask_type,
			       int len)
{
	if (!tb[val_type])
		return;
	nla_memcpy(val, tb[val_type], len);

	if (!mask)
		return;

	if (mask_type == TCA_CT_UNSPEC || !tb[mask_type])
		memset(mask, 0xff, len);
	else
		nla_memcpy(mask, tb[mask_type], len);
}

static int tcf_ct_fill_params(struct net *net,
			      struct tcf_ct_params *p,
			      struct tc_ct *parm,
			      struct nlattr **tb,
			      struct netlink_ext_ack *extack)
{
	struct tc_ct_action_net *tn = net_generic(net, ct_net_id);
	struct nf_conntrack_zone zone;
	struct nf_conn *tmpl;
	int err;

	p->zone = NF_CT_DEFAULT_ZONE_ID;

	tcf_ct_set_key_val(tb,
			   &p->ct_action, TCA_CT_ACTION,
			   NULL, TCA_CT_UNSPEC,
			   sizeof(p->ct_action));

	if (p->ct_action & TCA_CT_ACT_CLEAR)
		return 0;

	err = tcf_ct_fill_params_nat(p, parm, tb, extack);
	if (err)
		return err;

	if (tb[TCA_CT_MARK]) {
		if (!IS_ENABLED(CONFIG_NF_CONNTRACK_MARK)) {
			NL_SET_ERR_MSG_MOD(extack, "Conntrack mark isn't enabled.");
			return -EOPNOTSUPP;
		}
		tcf_ct_set_key_val(tb,
				   &p->mark, TCA_CT_MARK,
				   &p->mark_mask, TCA_CT_MARK_MASK,
				   sizeof(p->mark));
	}

	if (tb[TCA_CT_LABELS]) {
		if (!IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS)) {
			NL_SET_ERR_MSG_MOD(extack, "Conntrack labels isn't enabled.");
			return -EOPNOTSUPP;
		}

		if (!tn->labels) {
			NL_SET_ERR_MSG_MOD(extack, "Failed to set connlabel length");
			return -EOPNOTSUPP;
		}
		tcf_ct_set_key_val(tb,
				   p->labels, TCA_CT_LABELS,
				   p->labels_mask, TCA_CT_LABELS_MASK,
				   sizeof(p->labels));
	}

	if (tb[TCA_CT_ZONE]) {
		if (!IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES)) {
			NL_SET_ERR_MSG_MOD(extack, "Conntrack zones isn't enabled.");
			return -EOPNOTSUPP;
		}

		tcf_ct_set_key_val(tb,
				   &p->zone, TCA_CT_ZONE,
				   NULL, TCA_CT_UNSPEC,
				   sizeof(p->zone));
	}

	if (p->zone == NF_CT_DEFAULT_ZONE_ID)
		return 0;

	nf_ct_zone_init(&zone, p->zone, NF_CT_DEFAULT_ZONE_DIR, 0);
	tmpl = nf_ct_tmpl_alloc(net, &zone, GFP_KERNEL);
	if (!tmpl) {
		NL_SET_ERR_MSG_MOD(extack, "Failed to allocate conntrack template");
		return -ENOMEM;
	}
	__set_bit(IPS_CONFIRMED_BIT, &tmpl->status);
	nf_conntrack_get(&tmpl->ct_general);
	p->tmpl = tmpl;

	return 0;
}

static int tcf_ct_init(struct net *net, struct nlattr *nla,
		       struct nlattr *est, struct tc_action **a,
		       int replace, int bind, bool rtnl_held,
		       struct tcf_proto *tp, u32 flags,
		       struct netlink_ext_ack *extack)
{
	struct tc_action_net *tn = net_generic(net, ct_net_id);
	struct tcf_ct_params *params = NULL;
	struct nlattr *tb[TCA_CT_MAX + 1];
	struct tcf_chain *goto_ch = NULL;
	struct tc_ct *parm;
	struct tcf_ct *c;
	int err, res = 0;
	u32 index;

	if (!nla) {
		NL_SET_ERR_MSG_MOD(extack, "Ct requires attributes to be passed");
		return -EINVAL;
	}

	err = nla_parse_nested(tb, TCA_CT_MAX, nla, ct_policy, extack);
	if (err < 0)
		return err;

	if (!tb[TCA_CT_PARMS]) {
		NL_SET_ERR_MSG_MOD(extack, "Missing required ct parameters");
		return -EINVAL;
	}
	parm = nla_data(tb[TCA_CT_PARMS]);
	index = parm->index;
	err = tcf_idr_check_alloc(tn, &index, a, bind);
	if (err < 0)
		return err;

	if (!err) {
		err = tcf_idr_create_from_flags(tn, index, est, a,
						&act_ct_ops, bind, flags);
		if (err) {
			tcf_idr_cleanup(tn, index);
			return err;
		}
		res = ACT_P_CREATED;
	} else {
		if (bind)
			return 0;

		if (!replace) {
			tcf_idr_release(*a, bind);
			return -EEXIST;
		}
	}
	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
	if (err < 0)
		goto cleanup;

	c = to_ct(*a);

	params = kzalloc(sizeof(*params), GFP_KERNEL);
	if (unlikely(!params)) {
		err = -ENOMEM;
		goto cleanup;
	}

	err = tcf_ct_fill_params(net, params, parm, tb, extack);
	if (err)
		goto cleanup;

	err = tcf_ct_flow_table_get(params);
	if (err)
		goto cleanup;

	spin_lock_bh(&c->tcf_lock);
	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
	params = rcu_replace_pointer(c->params, params,
				     lockdep_is_held(&c->tcf_lock));
	spin_unlock_bh(&c->tcf_lock);

	if (goto_ch)
		tcf_chain_put_by_act(goto_ch);
	if (params)
		kfree_rcu(params, rcu);
	if (res == ACT_P_CREATED)
		tcf_idr_insert(tn, *a);

	return res;

cleanup:
	if (goto_ch)
		tcf_chain_put_by_act(goto_ch);
	kfree(params);
	tcf_idr_release(*a, bind);
	return err;
}

static void tcf_ct_cleanup(struct tc_action *a)
{
	struct tcf_ct_params *params;
	struct tcf_ct *c = to_ct(a);

	params = rcu_dereference_protected(c->params, 1);
	if (params)
		call_rcu(&params->rcu, tcf_ct_params_free);
}

static int tcf_ct_dump_key_val(struct sk_buff *skb,
			       void *val, int val_type,
			       void *mask, int mask_type,
			       int len)
{
	int err;

	if (mask && !memchr_inv(mask, 0, len))
		return 0;

	err = nla_put(skb, val_type, len, val);
	if (err)
		return err;

	if (mask_type != TCA_CT_UNSPEC) {
		err = nla_put(skb, mask_type, len, mask);
		if (err)
			return err;
	}

	return 0;
}

static int tcf_ct_dump_nat(struct sk_buff *skb, struct tcf_ct_params *p)
{
	struct nf_nat_range2 *range = &p->range;

	if (!(p->ct_action & TCA_CT_ACT_NAT))
		return 0;

	if (!(p->ct_action & (TCA_CT_ACT_NAT_SRC | TCA_CT_ACT_NAT_DST)))
		return 0;

	if (range->flags & NF_NAT_RANGE_MAP_IPS) {
		if (p->ipv4_range) {
			if (nla_put_in_addr(skb, TCA_CT_NAT_IPV4_MIN,
					    range->min_addr.ip))
				return -1;
			if (nla_put_in_addr(skb, TCA_CT_NAT_IPV4_MAX,
					    range->max_addr.ip))
				return -1;
		} else {
			if (nla_put_in6_addr(skb, TCA_CT_NAT_IPV6_MIN,
					     &range->min_addr.in6))
				return -1;
			if (nla_put_in6_addr(skb, TCA_CT_NAT_IPV6_MAX,
					     &range->max_addr.in6))
				return -1;
		}
	}

	if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
		if (nla_put_be16(skb, TCA_CT_NAT_PORT_MIN,
				 range->min_proto.all))
			return -1;
		if (nla_put_be16(skb, TCA_CT_NAT_PORT_MAX,
				 range->max_proto.all))
			return -1;
	}

	return 0;
}

static inline int tcf_ct_dump(struct sk_buff *skb, struct tc_action *a,
			      int bind, int ref)
{
	unsigned char *b = skb_tail_pointer(skb);
	struct tcf_ct *c = to_ct(a);
	struct tcf_ct_params *p;

	struct tc_ct opt = {
		.index   = c->tcf_index,
		.refcnt  = refcount_read(&c->tcf_refcnt) - ref,
		.bindcnt = atomic_read(&c->tcf_bindcnt) - bind,
	};
	struct tcf_t t;

	spin_lock_bh(&c->tcf_lock);
	p = rcu_dereference_protected(c->params,
				      lockdep_is_held(&c->tcf_lock));
	opt.action = c->tcf_action;

	if (tcf_ct_dump_key_val(skb,
				&p->ct_action, TCA_CT_ACTION,
				NULL, TCA_CT_UNSPEC,
				sizeof(p->ct_action)))
		goto nla_put_failure;

	if (p->ct_action & TCA_CT_ACT_CLEAR)
		goto skip_dump;

	if (IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) &&
	    tcf_ct_dump_key_val(skb,
				&p->mark, TCA_CT_MARK,
				&p->mark_mask, TCA_CT_MARK_MASK,
				sizeof(p->mark)))
		goto nla_put_failure;

	if (IS_ENABLED(CONFIG_NF_CONNTRACK_LABELS) &&
	    tcf_ct_dump_key_val(skb,
				p->labels, TCA_CT_LABELS,
				p->labels_mask, TCA_CT_LABELS_MASK,
				sizeof(p->labels)))
		goto nla_put_failure;

	if (IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) &&
	    tcf_ct_dump_key_val(skb,
				&p->zone, TCA_CT_ZONE,
				NULL, TCA_CT_UNSPEC,
				sizeof(p->zone)))
		goto nla_put_failure;

	if (tcf_ct_dump_nat(skb, p))
		goto nla_put_failure;

skip_dump:
	if (nla_put(skb, TCA_CT_PARMS, sizeof(opt), &opt))
		goto nla_put_failure;

	tcf_tm_dump(&t, &c->tcf_tm);
	if (nla_put_64bit(skb, TCA_CT_TM, sizeof(t), &t, TCA_CT_PAD))
		goto nla_put_failure;
	spin_unlock_bh(&c->tcf_lock);

	return skb->len;
nla_put_failure:
	spin_unlock_bh(&c->tcf_lock);
	nlmsg_trim(skb, b);
	return -1;
}

static int tcf_ct_walker(struct net *net, struct sk_buff *skb,
			 struct netlink_callback *cb, int type,
			 const struct tc_action_ops *ops,
			 struct netlink_ext_ack *extack)
{
	struct tc_action_net *tn = net_generic(net, ct_net_id);

	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
}

static int tcf_ct_search(struct net *net, struct tc_action **a, u32 index)
{
	struct tc_action_net *tn = net_generic(net, ct_net_id);

	return tcf_idr_search(tn, a, index);
}

static void tcf_stats_update(struct tc_action *a, u64 bytes, u32 packets,
			     u64 lastuse, bool hw)
{
	struct tcf_ct *c = to_ct(a);

	tcf_action_update_stats(a, bytes, packets, false, hw);
	c->tcf_tm.lastuse = max_t(u64, c->tcf_tm.lastuse, lastuse);
}

static struct tc_action_ops act_ct_ops = {
	.kind		=	"ct",
	.id		=	TCA_ID_CT,
	.owner		=	THIS_MODULE,
	.act		=	tcf_ct_act,
	.dump		=	tcf_ct_dump,
	.init		=	tcf_ct_init,
	.cleanup	=	tcf_ct_cleanup,
	.walk		=	tcf_ct_walker,
	.lookup		=	tcf_ct_search,
	.stats_update	=	tcf_stats_update,
	.size		=	sizeof(struct tcf_ct),
};

static __net_init int ct_init_net(struct net *net)
{
	unsigned int n_bits = sizeof_field(struct tcf_ct_params, labels) * 8;
	struct tc_ct_action_net *tn = net_generic(net, ct_net_id);

	if (nf_connlabels_get(net, n_bits - 1)) {
		tn->labels = false;
		pr_err("act_ct: Failed to set connlabels length");
	} else {
		tn->labels = true;
	}

	return tc_action_net_init(net, &tn->tn, &act_ct_ops);
}

static void __net_exit ct_exit_net(struct list_head *net_list)
{
	struct net *net;

	rtnl_lock();
	list_for_each_entry(net, net_list, exit_list) {
		struct tc_ct_action_net *tn = net_generic(net, ct_net_id);

		if (tn->labels)
			nf_connlabels_put(net);
	}
	rtnl_unlock();

	tc_action_net_exit(net_list, ct_net_id);
}

static struct pernet_operations ct_net_ops = {
	.init = ct_init_net,
	.exit_batch = ct_exit_net,
	.id   = &ct_net_id,
	.size = sizeof(struct tc_ct_action_net),
};

static int __init ct_init_module(void)
{
	int err;

	act_ct_wq = alloc_ordered_workqueue("act_ct_workqueue", 0);
	if (!act_ct_wq)
		return -ENOMEM;

	err = tcf_ct_flow_tables_init();
	if (err)
		goto err_tbl_init;

	err = tcf_register_action(&act_ct_ops, &ct_net_ops);
	if (err)
		goto err_register;

	return 0;

err_tbl_init:
	destroy_workqueue(act_ct_wq);
err_register:
	tcf_ct_flow_tables_uninit();
	return err;
}

static void __exit ct_cleanup_module(void)
{
	tcf_unregister_action(&act_ct_ops, &ct_net_ops);
	tcf_ct_flow_tables_uninit();
	destroy_workqueue(act_ct_wq);
}

module_init(ct_init_module);
module_exit(ct_cleanup_module);
MODULE_AUTHOR("Paul Blakey <paulb@mellanox.com>");
MODULE_AUTHOR("Yossi Kuperman <yossiku@mellanox.com>");
MODULE_AUTHOR("Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>");
MODULE_DESCRIPTION("Connection tracking action");
MODULE_LICENSE("GPL v2");