// SPDX-License-Identifier: GPL-2.0-only
/*
 * Connection tracking protocol helper module for SCTP.
 *
 * Copyright (c) 2004 Kiran Kumar Immidi <immidi_kiran@yahoo.com>
 * Copyright (c) 2004-2012 Patrick McHardy <kaber@trash.net>
 *
 * SCTP is defined in RFC 2960. References to various sections in this code
 * are to this RFC.
 */

#include <linux/types.h>
#include <linux/timer.h>
#include <linux/netfilter.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/sctp.h>
#include <linux/string.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <net/sctp/checksum.h>

#include <net/netfilter/nf_log.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_timeout.h>

static const char *const sctp_conntrack_names[] = {
	[SCTP_CONNTRACK_NONE]			= "NONE",
	[SCTP_CONNTRACK_CLOSED]			= "CLOSED",
	[SCTP_CONNTRACK_COOKIE_WAIT]		= "COOKIE_WAIT",
	[SCTP_CONNTRACK_COOKIE_ECHOED]		= "COOKIE_ECHOED",
	[SCTP_CONNTRACK_ESTABLISHED]		= "ESTABLISHED",
	[SCTP_CONNTRACK_SHUTDOWN_SENT]		= "SHUTDOWN_SENT",
	[SCTP_CONNTRACK_SHUTDOWN_RECD]		= "SHUTDOWN_RECD",
	[SCTP_CONNTRACK_SHUTDOWN_ACK_SENT]	= "SHUTDOWN_ACK_SENT",
	[SCTP_CONNTRACK_HEARTBEAT_SENT]		= "HEARTBEAT_SENT",
};

#define SECS  * HZ
#define MINS  * 60 SECS
#define HOURS * 60 MINS
#define DAYS  * 24 HOURS

static const unsigned int sctp_timeouts[SCTP_CONNTRACK_MAX] = {
	[SCTP_CONNTRACK_CLOSED]			= 10 SECS,
	[SCTP_CONNTRACK_COOKIE_WAIT]		= 3 SECS,
	[SCTP_CONNTRACK_COOKIE_ECHOED]		= 3 SECS,
	[SCTP_CONNTRACK_ESTABLISHED]		= 210 SECS,
	[SCTP_CONNTRACK_SHUTDOWN_SENT]		= 300 SECS / 1000,
	[SCTP_CONNTRACK_SHUTDOWN_RECD]		= 300 SECS / 1000,
	[SCTP_CONNTRACK_SHUTDOWN_ACK_SENT]	= 3 SECS,
	[SCTP_CONNTRACK_HEARTBEAT_SENT]		= 30 SECS,
};

#define	SCTP_FLAG_HEARTBEAT_VTAG_FAILED	1

#define sNO SCTP_CONNTRACK_NONE
#define	sCL SCTP_CONNTRACK_CLOSED
#define	sCW SCTP_CONNTRACK_COOKIE_WAIT
#define	sCE SCTP_CONNTRACK_COOKIE_ECHOED
#define	sES SCTP_CONNTRACK_ESTABLISHED
#define	sSS SCTP_CONNTRACK_SHUTDOWN_SENT
#define	sSR SCTP_CONNTRACK_SHUTDOWN_RECD
#define	sSA SCTP_CONNTRACK_SHUTDOWN_ACK_SENT
#define	sHS SCTP_CONNTRACK_HEARTBEAT_SENT
#define	sIV SCTP_CONNTRACK_MAX

/*
	These are the descriptions of the states:

NOTE: These state names are tantalizingly similar to the states of an
SCTP endpoint. But the interpretation of the states is a little different,
considering that these are the states of the connection and not of an end
point. Please note the subtleties. -Kiran

NONE              - Nothing so far.
COOKIE WAIT       - We have seen an INIT chunk in the original direction, or also
		    an INIT_ACK chunk in the reply direction.
COOKIE ECHOED     - We have seen a COOKIE_ECHO chunk in the original direction.
ESTABLISHED       - We have seen a COOKIE_ACK in the reply direction.
SHUTDOWN_SENT     - We have seen a SHUTDOWN chunk in the original direction.
SHUTDOWN_RECD     - We have seen a SHUTDOWN chunk in the reply direction.
SHUTDOWN_ACK_SENT - We have seen a SHUTDOWN_ACK chunk in the direction opposite
		    to that of the SHUTDOWN chunk.
CLOSED            - We have seen a SHUTDOWN_COMPLETE chunk in the direction of
		    the SHUTDOWN chunk. Connection is closed.
HEARTBEAT_SENT    - We have seen a HEARTBEAT in a new flow.
*/

/* TODO
 - I have assumed that the first INIT is in the original direction.
 This messes things when an INIT comes in the reply direction in CLOSED
 state.
 - Check the error type in the reply dir before transitioning from
cookie echoed to closed.
 - Sec 5.2.4 of RFC 2960
 - Full Multi Homing support.
*/

/* SCTP conntrack state transitions */
static const u8 sctp_conntracks[2][11][SCTP_CONNTRACK_MAX] = {
	{
/*	ORIGINAL	*/
/*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS */
/* init         */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCW},
/* init_ack     */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},
/* abort        */ {sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sCL},
/* shutdown     */ {sCL, sCL, sCW, sCE, sSS, sSS, sSR, sSA, sCL},
/* shutdown_ack */ {sSA, sCL, sCW, sCE, sES, sSA, sSA, sSA, sSA},
/* error        */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},/* Can't have Stale cookie*/
/* cookie_echo  */ {sCL, sCL, sCE, sCE, sES, sSS, sSR, sSA, sCL},/* 5.2.4 - Big TODO */
/* cookie_ack   */ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sCL},/* Can't come in orig dir */
/* shutdown_comp*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sCL, sCL},
/* heartbeat    */ {sHS, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
/* heartbeat_ack*/ {sCL, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
	},
	{
/*	REPLY	*/
/*                  sNO, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS */
/* init         */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sIV},/* INIT in sCL Big TODO */
/* init_ack     */ {sIV, sCW, sCW, sCE, sES, sSS, sSR, sSA, sIV},
/* abort        */ {sIV, sCL, sCL, sCL, sCL, sCL, sCL, sCL, sIV},
/* shutdown     */ {sIV, sCL, sCW, sCE, sSR, sSS, sSR, sSA, sIV},
/* shutdown_ack */ {sIV, sCL, sCW, sCE, sES, sSA, sSA, sSA, sIV},
/* error        */ {sIV, sCL, sCW, sCL, sES, sSS, sSR, sSA, sIV},
/* cookie_echo  */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sIV},/* Can't come in reply dir */
/* cookie_ack   */ {sIV, sCL, sCW, sES, sES, sSS, sSR, sSA, sIV},
/* shutdown_comp*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sCL, sIV},
/* heartbeat    */ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sHS},
/* heartbeat_ack*/ {sIV, sCL, sCW, sCE, sES, sSS, sSR, sSA, sES},
	}
};

#ifdef CONFIG_NF_CONNTRACK_PROCFS
/* Print out the private part of the conntrack. */
static void sctp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
{
	seq_printf(s, "%s ", sctp_conntrack_names[ct->proto.sctp.state]);
}
#endif

#define for_each_sctp_chunk(skb, sch, _sch, offset, dataoff, count)	\
for ((offset) = (dataoff) + sizeof(struct sctphdr), (count) = 0;	\
	((sch) = skb_header_pointer((skb), (offset), sizeof(_sch), &(_sch))) &&	\
	(sch)->length;	\
	(offset) += (ntohs((sch)->length) + 3) & ~3, (count)++)

/* Some validity checks to make sure the chunks are fine */
static int do_basic_checks(struct nf_conn *ct,
			   const struct sk_buff *skb,
			   unsigned int dataoff,
			   unsigned long *map)
{
	u_int32_t offset, count;
	struct sctp_chunkhdr _sch, *sch;
	int flag;

	flag = 0;

	for_each_sctp_chunk (skb, sch, _sch, offset, dataoff, count) {
		pr_debug("Chunk Num: %d  Type: %d\n", count, sch->type);

		if (sch->type == SCTP_CID_INIT ||
		    sch->type == SCTP_CID_INIT_ACK ||
		    sch->type == SCTP_CID_SHUTDOWN_COMPLETE)
			flag = 1;

		/*
		 * Cookie Ack/Echo chunks not the first OR
		 * Init / Init Ack / Shutdown compl chunks not the only chunks
		 * OR zero-length.
		 */
		if (((sch->type == SCTP_CID_COOKIE_ACK ||
		      sch->type == SCTP_CID_COOKIE_ECHO ||
		      flag) &&
		     count != 0) || !sch->length) {
			pr_debug("Basic checks failed\n");
			return 1;
		}

		if (map)
			set_bit(sch->type, map);
	}

	pr_debug("Basic checks passed\n");
	return count == 0;
}

static int sctp_new_state(enum ip_conntrack_dir dir,
			  enum sctp_conntrack cur_state,
			  int chunk_type)
{
	int i;

	pr_debug("Chunk type: %d\n", chunk_type);

	switch (chunk_type) {
	case SCTP_CID_INIT:
		pr_debug("SCTP_CID_INIT\n");
		i = 0;
		break;
	case SCTP_CID_INIT_ACK:
		pr_debug("SCTP_CID_INIT_ACK\n");
		i = 1;
		break;
	case SCTP_CID_ABORT:
		pr_debug("SCTP_CID_ABORT\n");
		i = 2;
		break;
	case SCTP_CID_SHUTDOWN:
		pr_debug("SCTP_CID_SHUTDOWN\n");
		i = 3;
		break;
	case SCTP_CID_SHUTDOWN_ACK:
		pr_debug("SCTP_CID_SHUTDOWN_ACK\n");
		i = 4;
		break;
	case SCTP_CID_ERROR:
		pr_debug("SCTP_CID_ERROR\n");
		i = 5;
		break;
	case SCTP_CID_COOKIE_ECHO:
		pr_debug("SCTP_CID_COOKIE_ECHO\n");
		i = 6;
		break;
	case SCTP_CID_COOKIE_ACK:
		pr_debug("SCTP_CID_COOKIE_ACK\n");
		i = 7;
		break;
	case SCTP_CID_SHUTDOWN_COMPLETE:
		pr_debug("SCTP_CID_SHUTDOWN_COMPLETE\n");
		i = 8;
		break;
	case SCTP_CID_HEARTBEAT:
		pr_debug("SCTP_CID_HEARTBEAT");
		i = 9;
		break;
	case SCTP_CID_HEARTBEAT_ACK:
		pr_debug("SCTP_CID_HEARTBEAT_ACK");
		i = 10;
		break;
	default:
		/* Other chunks like DATA or SACK do not change the state */
		pr_debug("Unknown chunk type, Will stay in %s\n",
			 sctp_conntrack_names[cur_state]);
		return cur_state;
	}

	pr_debug("dir: %d   cur_state: %s  chunk_type: %d  new_state: %s\n",
		 dir, sctp_conntrack_names[cur_state], chunk_type,
		 sctp_conntrack_names[sctp_conntracks[dir][i][cur_state]]);

	return sctp_conntracks[dir][i][cur_state];
}

/* Don't need lock here: this conntrack not in circulation yet */
static noinline bool
sctp_new(struct nf_conn *ct, const struct sk_buff *skb,
	 const struct sctphdr *sh, unsigned int dataoff)
{
	enum sctp_conntrack new_state;
	const struct sctp_chunkhdr *sch;
	struct sctp_chunkhdr _sch;
	u32 offset, count;

	memset(&ct->proto.sctp, 0, sizeof(ct->proto.sctp));
	new_state = SCTP_CONNTRACK_MAX;
	for_each_sctp_chunk(skb, sch, _sch, offset, dataoff, count) {
		new_state = sctp_new_state(IP_CT_DIR_ORIGINAL,
					   SCTP_CONNTRACK_NONE, sch->type);

		/* Invalid: delete conntrack */
		if (new_state == SCTP_CONNTRACK_NONE ||
		    new_state == SCTP_CONNTRACK_MAX) {
			pr_debug("nf_conntrack_sctp: invalid new deleting.\n");
			return false;
		}

		/* Copy the vtag into the state info */
		if (sch->type == SCTP_CID_INIT) {
			struct sctp_inithdr _inithdr, *ih;
			/* Sec 8.5.1 (A) */
			if (sh->vtag)
				return false;

			ih = skb_header_pointer(skb, offset + sizeof(_sch),
						sizeof(_inithdr), &_inithdr);
			if (!ih)
				return false;

			pr_debug("Setting vtag %x for new conn\n",
				 ih->init_tag);

			ct->proto.sctp.vtag[IP_CT_DIR_REPLY] = ih->init_tag;
		} else if (sch->type == SCTP_CID_HEARTBEAT) {
			pr_debug("Setting vtag %x for secondary conntrack\n",
				 sh->vtag);
			ct->proto.sctp.vtag[IP_CT_DIR_ORIGINAL] = sh->vtag;
		} else {
		/* If it is a shutdown ack OOTB packet, we expect a return
		   shutdown complete, otherwise an ABORT Sec 8.4 (5) and (8) */
			pr_debug("Setting vtag %x for new conn OOTB\n",
				 sh->vtag);
			ct->proto.sctp.vtag[IP_CT_DIR_REPLY] = sh->vtag;
		}

		ct->proto.sctp.state = SCTP_CONNTRACK_NONE;
	}

	return true;
}

static bool sctp_error(struct sk_buff *skb,
		       unsigned int dataoff,
		       const struct nf_hook_state *state)
{
	const struct sctphdr *sh;
	const char *logmsg;

	if (skb->len < dataoff + sizeof(struct sctphdr)) {
		logmsg = "nf_ct_sctp: short packet ";
		goto out_invalid;
	}
	if (state->hook == NF_INET_PRE_ROUTING &&
	    state->net->ct.sysctl_checksum &&
	    skb->ip_summed == CHECKSUM_NONE) {
		if (skb_ensure_writable(skb, dataoff + sizeof(*sh))) {
			logmsg = "nf_ct_sctp: failed to read header ";
			goto out_invalid;
		}
		sh = (const struct sctphdr *)(skb->data + dataoff);
		if (sh->checksum != sctp_compute_cksum(skb, dataoff)) {
			logmsg = "nf_ct_sctp: bad CRC ";
			goto out_invalid;
		}
		skb->ip_summed = CHECKSUM_UNNECESSARY;
	}
	return false;
out_invalid:
	nf_l4proto_log_invalid(skb, state, IPPROTO_SCTP, "%s", logmsg);
	return true;
}

/* Returns verdict for packet, or -NF_ACCEPT for invalid. */
int nf_conntrack_sctp_packet(struct nf_conn *ct,
			     struct sk_buff *skb,
			     unsigned int dataoff,
			     enum ip_conntrack_info ctinfo,
			     const struct nf_hook_state *state)
{
	enum sctp_conntrack new_state, old_state;
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	const struct sctphdr *sh;
	struct sctphdr _sctph;
	const struct sctp_chunkhdr *sch;
	struct sctp_chunkhdr _sch;
	u_int32_t offset, count;
	unsigned int *timeouts;
	unsigned long map[256 / sizeof(unsigned long)] = { 0 };
	bool ignore = false;

	if (sctp_error(skb, dataoff, state))
		return -NF_ACCEPT;

	sh = skb_header_pointer(skb, dataoff, sizeof(_sctph), &_sctph);
	if (sh == NULL)
		goto out;

	if (do_basic_checks(ct, skb, dataoff, map) != 0)
		goto out;

	if (!nf_ct_is_confirmed(ct)) {
		/* If an OOTB packet has any of these chunks discard (Sec 8.4) */
		if (test_bit(SCTP_CID_ABORT, map) ||
		    test_bit(SCTP_CID_SHUTDOWN_COMPLETE, map) ||
		    test_bit(SCTP_CID_COOKIE_ACK, map))
			return -NF_ACCEPT;

		if (!sctp_new(ct, skb, sh, dataoff))
			return -NF_ACCEPT;
	}

	/* Check the verification tag (Sec 8.5) */
	if (!test_bit(SCTP_CID_INIT, map) &&
	    !test_bit(SCTP_CID_SHUTDOWN_COMPLETE, map) &&
	    !test_bit(SCTP_CID_COOKIE_ECHO, map) &&
	    !test_bit(SCTP_CID_ABORT, map) &&
	    !test_bit(SCTP_CID_SHUTDOWN_ACK, map) &&
	    !test_bit(SCTP_CID_HEARTBEAT, map) &&
	    !test_bit(SCTP_CID_HEARTBEAT_ACK, map) &&
	    sh->vtag != ct->proto.sctp.vtag[dir]) {
		pr_debug("Verification tag check failed\n");
		goto out;
	}

	old_state = new_state = SCTP_CONNTRACK_NONE;
	spin_lock_bh(&ct->lock);
	for_each_sctp_chunk (skb, sch, _sch, offset, dataoff, count) {
		/* Special cases of Verification tag check (Sec 8.5.1) */
		if (sch->type == SCTP_CID_INIT) {
			/* (A) vtag MUST be zero */
			if (sh->vtag != 0)
				goto out_unlock;
		} else if (sch->type == SCTP_CID_ABORT) {
			/* (B) vtag MUST match own vtag if T flag is unset OR
			 * MUST match peer's vtag if T flag is set
			 */
			if ((!(sch->flags & SCTP_CHUNK_FLAG_T) &&
			     sh->vtag != ct->proto.sctp.vtag[dir]) ||
			    ((sch->flags & SCTP_CHUNK_FLAG_T) &&
			     sh->vtag != ct->proto.sctp.vtag[!dir]))
				goto out_unlock;
		} else if (sch->type == SCTP_CID_SHUTDOWN_COMPLETE) {
			/* (C) vtag MUST match own vtag if T flag is unset OR
			 * MUST match peer's vtag if T flag is set
			 */
			if ((!(sch->flags & SCTP_CHUNK_FLAG_T) &&
			     sh->vtag != ct->proto.sctp.vtag[dir]) ||
			    ((sch->flags & SCTP_CHUNK_FLAG_T) &&
			     sh->vtag != ct->proto.sctp.vtag[!dir]))
				goto out_unlock;
		} else if (sch->type == SCTP_CID_COOKIE_ECHO) {
			/* (D) vtag must be same as init_vtag as found in INIT_ACK */
			if (sh->vtag != ct->proto.sctp.vtag[dir])
				goto out_unlock;
		} else if (sch->type == SCTP_CID_HEARTBEAT) {
			if (ct->proto.sctp.vtag[dir] == 0) {
				pr_debug("Setting %d vtag %x for dir %d\n", sch->type, sh->vtag, dir);
				ct->proto.sctp.vtag[dir] = sh->vtag;
			} else if (sh->vtag != ct->proto.sctp.vtag[dir]) {
				if (test_bit(SCTP_CID_DATA, map) || ignore)
					goto out_unlock;

				ct->proto.sctp.flags |= SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
				ct->proto.sctp.last_dir = dir;
				ignore = true;
				continue;
			} else if (ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) {
				ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
			}
		} else if (sch->type == SCTP_CID_HEARTBEAT_ACK) {
			if (ct->proto.sctp.vtag[dir] == 0) {
				pr_debug("Setting vtag %x for dir %d\n",
					 sh->vtag, dir);
				ct->proto.sctp.vtag[dir] = sh->vtag;
			} else if (sh->vtag != ct->proto.sctp.vtag[dir]) {
				if (test_bit(SCTP_CID_DATA, map) || ignore)
					goto out_unlock;

				if ((ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) == 0 ||
				    ct->proto.sctp.last_dir == dir)
					goto out_unlock;

				ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
				ct->proto.sctp.vtag[dir] = sh->vtag;
				ct->proto.sctp.vtag[!dir] = 0;
			} else if (ct->proto.sctp.flags & SCTP_FLAG_HEARTBEAT_VTAG_FAILED) {
				ct->proto.sctp.flags &= ~SCTP_FLAG_HEARTBEAT_VTAG_FAILED;
			}
		}

		old_state = ct->proto.sctp.state;
		new_state = sctp_new_state(dir, old_state, sch->type);

		/* Invalid */
		if (new_state == SCTP_CONNTRACK_MAX) {
			pr_debug("nf_conntrack_sctp: Invalid dir=%i ctype=%u "
				 "conntrack=%u\n",
				 dir, sch->type, old_state);
			goto out_unlock;
		}

		/* If it is an INIT or an INIT ACK note down the vtag */
		if (sch->type == SCTP_CID_INIT ||
		    sch->type == SCTP_CID_INIT_ACK) {
			struct sctp_inithdr _inithdr, *ih;

			ih = skb_header_pointer(skb, offset + sizeof(_sch),
						sizeof(_inithdr), &_inithdr);
			if (ih == NULL)
				goto out_unlock;
			pr_debug("Setting vtag %x for dir %d\n",
				 ih->init_tag, !dir);
			ct->proto.sctp.vtag[!dir] = ih->init_tag;

			/* don't renew timeout on init retransmit so
			 * port reuse by client or NAT middlebox cannot
			 * keep entry alive indefinitely (incl. nat info).
			 */
			if (new_state == SCTP_CONNTRACK_CLOSED &&
			    old_state == SCTP_CONNTRACK_CLOSED &&
			    nf_ct_is_confirmed(ct))
				ignore = true;
		}

		ct->proto.sctp.state = new_state;
		if (old_state != new_state) {
			nf_conntrack_event_cache(IPCT_PROTOINFO, ct);
			if (new_state == SCTP_CONNTRACK_ESTABLISHED &&
			    !test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
				nf_conntrack_event_cache(IPCT_ASSURED, ct);
		}
	}
	spin_unlock_bh(&ct->lock);

	/* allow but do not refresh timeout */
	if (ignore)
		return NF_ACCEPT;

	timeouts = nf_ct_timeout_lookup(ct);
	if (!timeouts)
		timeouts = nf_sctp_pernet(nf_ct_net(ct))->timeouts;

	nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);

	return NF_ACCEPT;

out_unlock:
	spin_unlock_bh(&ct->lock);
out:
	return -NF_ACCEPT;
}

static bool sctp_can_early_drop(const struct nf_conn *ct)
{
	switch (ct->proto.sctp.state) {
	case SCTP_CONNTRACK_SHUTDOWN_SENT:
	case SCTP_CONNTRACK_SHUTDOWN_RECD:
	case SCTP_CONNTRACK_SHUTDOWN_ACK_SENT:
		return true;
	default:
		break;
	}

	return false;
}

#if IS_ENABLED(CONFIG_NF_CT_NETLINK)

#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>

static int sctp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
			  struct nf_conn *ct, bool destroy)
{
	struct nlattr *nest_parms;

	spin_lock_bh(&ct->lock);
	nest_parms = nla_nest_start(skb, CTA_PROTOINFO_SCTP);
	if (!nest_parms)
		goto nla_put_failure;

	if (nla_put_u8(skb, CTA_PROTOINFO_SCTP_STATE, ct->proto.sctp.state))
		goto nla_put_failure;

	if (destroy)
		goto skip_state;

	if (nla_put_be32(skb, CTA_PROTOINFO_SCTP_VTAG_ORIGINAL,
			 ct->proto.sctp.vtag[IP_CT_DIR_ORIGINAL]) ||
	    nla_put_be32(skb, CTA_PROTOINFO_SCTP_VTAG_REPLY,
			 ct->proto.sctp.vtag[IP_CT_DIR_REPLY]))
		goto nla_put_failure;

skip_state:
	spin_unlock_bh(&ct->lock);
	nla_nest_end(skb, nest_parms);

	return 0;

nla_put_failure:
	spin_unlock_bh(&ct->lock);
	return -1;
}

static const struct nla_policy sctp_nla_policy[CTA_PROTOINFO_SCTP_MAX+1] = {
	[CTA_PROTOINFO_SCTP_STATE]	    = { .type = NLA_U8 },
	[CTA_PROTOINFO_SCTP_VTAG_ORIGINAL]  = { .type = NLA_U32 },
	[CTA_PROTOINFO_SCTP_VTAG_REPLY]     = { .type = NLA_U32 },
};

#define SCTP_NLATTR_SIZE ( \
		NLA_ALIGN(NLA_HDRLEN + 1) + \
		NLA_ALIGN(NLA_HDRLEN + 4) + \
		NLA_ALIGN(NLA_HDRLEN + 4))

static int nlattr_to_sctp(struct nlattr *cda[], struct nf_conn *ct)
{
	struct nlattr *attr = cda[CTA_PROTOINFO_SCTP];
	struct nlattr *tb[CTA_PROTOINFO_SCTP_MAX+1];
	int err;

	/* updates may not contain the internal protocol info, skip parsing */
	if (!attr)
		return 0;

	err = nla_parse_nested_deprecated(tb, CTA_PROTOINFO_SCTP_MAX, attr,
					  sctp_nla_policy, NULL);
	if (err < 0)
		return err;

	if (!tb[CTA_PROTOINFO_SCTP_STATE] ||
	    !tb[CTA_PROTOINFO_SCTP_VTAG_ORIGINAL] ||
	    !tb[CTA_PROTOINFO_SCTP_VTAG_REPLY])
		return -EINVAL;

	spin_lock_bh(&ct->lock);
	ct->proto.sctp.state = nla_get_u8(tb[CTA_PROTOINFO_SCTP_STATE]);
	ct->proto.sctp.vtag[IP_CT_DIR_ORIGINAL] =
		nla_get_be32(tb[CTA_PROTOINFO_SCTP_VTAG_ORIGINAL]);
	ct->proto.sctp.vtag[IP_CT_DIR_REPLY] =
		nla_get_be32(tb[CTA_PROTOINFO_SCTP_VTAG_REPLY]);
	spin_unlock_bh(&ct->lock);

	return 0;
}
#endif

#ifdef CONFIG_NF_CONNTRACK_TIMEOUT

#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_cttimeout.h>

static int sctp_timeout_nlattr_to_obj(struct nlattr *tb[],
				      struct net *net, void *data)
{
	unsigned int *timeouts = data;
	struct nf_sctp_net *sn = nf_sctp_pernet(net);
	int i;

	if (!timeouts)
		timeouts = sn->timeouts;

	/* set default SCTP timeouts. */
	for (i=0; i<SCTP_CONNTRACK_MAX; i++)
		timeouts[i] = sn->timeouts[i];

	/* there's a 1:1 mapping between attributes and protocol states. */
	for (i=CTA_TIMEOUT_SCTP_UNSPEC+1; i<CTA_TIMEOUT_SCTP_MAX+1; i++) {
		if (tb[i]) {
			timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ;
		}
	}

	timeouts[CTA_TIMEOUT_SCTP_UNSPEC] = timeouts[CTA_TIMEOUT_SCTP_CLOSED];
	return 0;
}

static int
sctp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
{
        const unsigned int *timeouts = data;
	int i;

	for (i=CTA_TIMEOUT_SCTP_UNSPEC+1; i<CTA_TIMEOUT_SCTP_MAX+1; i++) {
	        if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ)))
			goto nla_put_failure;
	}
        return 0;

nla_put_failure:
        return -ENOSPC;
}

static const struct nla_policy
sctp_timeout_nla_policy[CTA_TIMEOUT_SCTP_MAX+1] = {
	[CTA_TIMEOUT_SCTP_CLOSED]		= { .type = NLA_U32 },
	[CTA_TIMEOUT_SCTP_COOKIE_WAIT]		= { .type = NLA_U32 },
	[CTA_TIMEOUT_SCTP_COOKIE_ECHOED]	= { .type = NLA_U32 },
	[CTA_TIMEOUT_SCTP_ESTABLISHED]		= { .type = NLA_U32 },
	[CTA_TIMEOUT_SCTP_SHUTDOWN_SENT]	= { .type = NLA_U32 },
	[CTA_TIMEOUT_SCTP_SHUTDOWN_RECD]	= { .type = NLA_U32 },
	[CTA_TIMEOUT_SCTP_SHUTDOWN_ACK_SENT]	= { .type = NLA_U32 },
	[CTA_TIMEOUT_SCTP_HEARTBEAT_SENT]	= { .type = NLA_U32 },
	[CTA_TIMEOUT_SCTP_HEARTBEAT_ACKED]	= { .type = NLA_U32 },
};
#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */

void nf_conntrack_sctp_init_net(struct net *net)
{
	struct nf_sctp_net *sn = nf_sctp_pernet(net);
	int i;

	for (i = 0; i < SCTP_CONNTRACK_MAX; i++)
		sn->timeouts[i] = sctp_timeouts[i];

	/* timeouts[0] is unused, init it so ->timeouts[0] contains
	 * 'new' timeout, like udp or icmp.
	 */
	sn->timeouts[0] = sctp_timeouts[SCTP_CONNTRACK_CLOSED];
}

const struct nf_conntrack_l4proto nf_conntrack_l4proto_sctp = {
	.l4proto 		= IPPROTO_SCTP,
#ifdef CONFIG_NF_CONNTRACK_PROCFS
	.print_conntrack	= sctp_print_conntrack,
#endif
	.can_early_drop		= sctp_can_early_drop,
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
	.nlattr_size		= SCTP_NLATTR_SIZE,
	.to_nlattr		= sctp_to_nlattr,
	.from_nlattr		= nlattr_to_sctp,
	.tuple_to_nlattr	= nf_ct_port_tuple_to_nlattr,
	.nlattr_tuple_size	= nf_ct_port_nlattr_tuple_size,
	.nlattr_to_tuple	= nf_ct_port_nlattr_to_tuple,
	.nla_policy		= nf_ct_port_nla_policy,
#endif
#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
	.ctnl_timeout		= {
		.nlattr_to_obj	= sctp_timeout_nlattr_to_obj,
		.obj_to_nlattr	= sctp_timeout_obj_to_nlattr,
		.nlattr_max	= CTA_TIMEOUT_SCTP_MAX,
		.obj_size	= sizeof(unsigned int) * SCTP_CONNTRACK_MAX,
		.nla_policy	= sctp_timeout_nla_policy,
	},
#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
};