C++ NF_CT_ASSERT函数代码示例

static unsigned int ipt_dnat_target(struct sk_buff *skb,
				    const struct net_device *in,
				    const struct net_device *out,
				    unsigned int hooknum,
				    const struct xt_target *target,
				    const void *targinfo)
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	const struct nf_nat_multi_range_compat *mr = targinfo;

	NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING ||
		     hooknum == NF_IP_LOCAL_OUT);

	ct = nf_ct_get(skb, &ctinfo);

	/* Connection must be valid and new. */
	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));

	if (hooknum == NF_IP_LOCAL_OUT &&
	    mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
		warn_if_extra_mangle(ip_hdr(skb)->daddr,
				     mr->range[0].min_ip);

	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
}

unsigned int
nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum,
		       const struct nf_nat_range *range,
		       const struct net_device *out)
{
	struct nf_conn *ct;
	struct nf_conn_nat *nat;
	enum ip_conntrack_info ctinfo;
	struct nf_nat_range newrange;
	const struct rtable *rt;
	__be32 newsrc, nh;

	NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING);

	ct = nf_ct_get(skb, &ctinfo);
	nat = nfct_nat(ct);

	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
			    ctinfo == IP_CT_RELATED_REPLY));

	/* Source address is 0.0.0.0 - locally generated packet that is
	 * probably not supposed to be masqueraded.
	 */
	if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0)
		return NF_ACCEPT;

	rt = skb_rtable(skb);
	nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
	newsrc = inet_select_addr(out, nh, RT_SCOPE_UNIVERSE);
	if (!newsrc) {
		pr_info("%s ate my IP address\n", out->name);
		return NF_DROP;
	}

	nat->masq_index = out->ifindex;

	/* Transfer from original range. */
	memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
	memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
	newrange.flags       = range->flags | NF_NAT_RANGE_MAP_IPS;
	newrange.min_addr.ip = newsrc;
	newrange.max_addr.ip = newsrc;
	newrange.min_proto   = range->min_proto;
	newrange.max_proto   = range->max_proto;

	/* Hand modified range to generic setup. */
	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
}

static unsigned int
netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	__be32 new_ip, netmask;
	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
	struct nf_nat_range newrange;

	NF_CT_ASSERT(xt_hooknum(par) == NF_INET_PRE_ROUTING ||
		     xt_hooknum(par) == NF_INET_POST_ROUTING ||
		     xt_hooknum(par) == NF_INET_LOCAL_OUT ||
		     xt_hooknum(par) == NF_INET_LOCAL_IN);
	ct = nf_ct_get(skb, &ctinfo);

	netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);

	if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
	    xt_hooknum(par) == NF_INET_LOCAL_OUT)
		new_ip = ip_hdr(skb)->daddr & ~netmask;
	else
		new_ip = ip_hdr(skb)->saddr & ~netmask;
	new_ip |= mr->range[0].min_ip & netmask;

	memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
	memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
	newrange.flags	     = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
	newrange.min_addr.ip = new_ip;
	newrange.max_addr.ip = new_ip;
	newrange.min_proto   = mr->range[0].min;
	newrange.max_proto   = mr->range[0].max;

	/* Hand modified range to generic setup. */
	return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
}

static unsigned int
masquerade_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct nf_nat_range *range = par->targinfo;
	enum ip_conntrack_info ctinfo;
	struct in6_addr src;
	struct nf_conn *ct;
	struct nf_nat_range newrange;

	ct = nf_ct_get(skb, &ctinfo);
	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
			    ctinfo == IP_CT_RELATED_REPLY));

	if (ipv6_dev_get_saddr(dev_net(par->out), par->out,
			       &ipv6_hdr(skb)->daddr, 0, &src) < 0)
		return NF_DROP;

	nfct_nat(ct)->masq_index = par->out->ifindex;

	newrange.flags		= range->flags | NF_NAT_RANGE_MAP_IPS;
	newrange.min_addr.in6	= src;
	newrange.max_addr.in6	= src;
	newrange.min_proto	= range->min_proto;
	newrange.max_proto	= range->max_proto;

	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
}

static unsigned int
ipt_dnat_target(struct sk_buff *skb, const struct xt_action_param *par)
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	const struct nf_nat_multi_range_compat *mr = par->targinfo;

	NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
		     par->hooknum == NF_INET_LOCAL_OUT);

	ct = nf_ct_get(skb, &ctinfo);

	/* Connection must be valid and new. */
	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));

	return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST);
}

/* Source NAT */
static unsigned int
ipt_snat_target(struct sk_buff *skb, const struct xt_action_param *par)
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	const struct nf_nat_multi_range_compat *mr = par->targinfo;

	NF_CT_ASSERT(par->hooknum == NF_IP_POST_ROUTING);

	ct = nf_ct_get(skb, &ctinfo);

	/* Connection must be valid and new. */
	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
			    ctinfo == IP_CT_RELATED_REPLY));
	NF_CT_ASSERT(par->out != NULL);

	return nf_nat_setup_info(ct, &mr->range[0], par->hooknum);
}

static unsigned int nf_nat_fn(const struct nf_hook_ops *ops,
			      struct sk_buff *skb,
			      const struct net_device *in,
			      const struct net_device *out,
			      int (*okfn)(struct sk_buff *))
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	struct nf_conn_nat *nat;
	enum nf_nat_manip_type maniptype = HOOK2MANIP(ops->hooknum);
	unsigned int ret;

	if (ct == NULL || nf_ct_is_untracked(ct))
		return NF_ACCEPT;

	NF_CT_ASSERT(!(ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)));

	nat = nfct_nat(ct);
	if (nat == NULL) {
		/* Conntrack module was loaded late, can't add extension. */
		if (nf_ct_is_confirmed(ct))
			return NF_ACCEPT;
		nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
		if (nat == NULL)
			return NF_ACCEPT;
	}

	switch (ctinfo) {
	case IP_CT_RELATED:
	case IP_CT_RELATED + IP_CT_IS_REPLY:
		if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
			if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
							   ops->hooknum))
				return NF_DROP;
			else
				return NF_ACCEPT;
		}
		/* Fall through */
	case IP_CT_NEW:
		if (nf_nat_initialized(ct, maniptype))
			break;

		ret = nft_do_chain(ops, skb, in, out, okfn);
		if (ret != NF_ACCEPT)
			return ret;
		if (!nf_nat_initialized(ct, maniptype)) {
			ret = nf_nat_alloc_null_binding(ct, ops->hooknum);
			if (ret != NF_ACCEPT)
				return ret;
		}
	default:
		break;
	}

	return nf_nat_packet(ct, ctinfo, ops->hooknum, skb);
}

static unsigned int
ipt_dnat_target(struct sk_buff *skb, const struct xt_target_param *par)
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	const struct nf_nat_multi_range_compat *mr = par->targinfo;

	NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
		     par->hooknum == NF_INET_LOCAL_OUT);

	ct = nf_ct_get(skb, &ctinfo);

	/* Connection must be valid and new. */
	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));

	if (par->hooknum == NF_INET_LOCAL_OUT &&
	    mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
		warn_if_extra_mangle(dev_net(par->out), ip_hdr(skb)->daddr,
				     mr->range[0].min_ip);

	return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST);
}

/* Source NAT */
static unsigned int ipt_snat_target(struct sk_buff *skb,
				    const struct net_device *in,
				    const struct net_device *out,
				    unsigned int hooknum,
				    const struct xt_target *target,
				    const void *targinfo)
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	const struct nf_nat_multi_range_compat *mr = targinfo;

	NF_CT_ASSERT(hooknum == NF_IP_POST_ROUTING);

	ct = nf_ct_get(skb, &ctinfo);

	/* Connection must be valid and new. */
	NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
			    ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
	NF_CT_ASSERT(out);

	return nf_nat_setup_info(ct, &mr->range[0], hooknum);
}

static int
icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
		     struct sk_buff *skb,
		     unsigned int icmp6off,
		     enum ip_conntrack_info *ctinfo,
		     unsigned int hooknum)
{
	struct nf_conntrack_tuple intuple, origtuple;
	const struct nf_conntrack_tuple_hash *h;
	const struct nf_conntrack_l4proto *inproto;
	u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;

	NF_CT_ASSERT(skb->nfct == NULL);

	
	if (!nf_ct_get_tuplepr(skb,
			       skb_network_offset(skb)
				+ sizeof(struct ipv6hdr)
				+ sizeof(struct icmp6hdr),
			       PF_INET6, &origtuple)) {
		pr_debug("icmpv6_error: Can't get tuple\n");
		return -NF_ACCEPT;
	}

	
	inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);

	if (!nf_ct_invert_tuple(&intuple, &origtuple,
				&nf_conntrack_l3proto_ipv6, inproto)) {
		pr_debug("icmpv6_error: Can't invert tuple\n");
		return -NF_ACCEPT;
	}

	*ctinfo = IP_CT_RELATED;

	h = nf_conntrack_find_get(net, zone, &intuple);
	if (!h) {
		pr_debug("icmpv6_error: no match\n");
		return -NF_ACCEPT;
	} else {
		if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
			*ctinfo += IP_CT_IS_REPLY;
	}

	
	skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
	skb->nfctinfo = *ctinfo;
	return NF_ACCEPT;
}

/* Returns conntrack if it dealt with ICMP, and filled in skb fields */
static int
icmp_error_message(struct sk_buff *skb,
		 enum ip_conntrack_info *ctinfo,
		 unsigned int hooknum)
{
	struct nf_conntrack_tuple innertuple, origtuple;
	struct nf_conntrack_l4proto *innerproto;
	struct nf_conntrack_tuple_hash *h;

	NF_CT_ASSERT(skb->nfct == NULL);

	/* Are they talking about one of our connections? */
	if (!nf_ct_get_tuplepr(skb,
			       skb_network_offset(skb) + ip_hdrlen(skb)
						       + sizeof(struct icmphdr),
			       PF_INET, &origtuple)) {
		pr_debug("icmp_error_message: failed to get tuple\n");
		return -NF_ACCEPT;
	}

	/* rcu_read_lock()ed by nf_hook_slow */
	innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);

	/* Ordinarily, we'd expect the inverted tupleproto, but it's
	   been preserved inside the ICMP. */
	if (!nf_ct_invert_tuple(&innertuple, &origtuple,
				&nf_conntrack_l3proto_ipv4, innerproto)) {
		pr_debug("icmp_error_message: no match\n");
		return -NF_ACCEPT;
	}

	*ctinfo = IP_CT_RELATED;

	h = nf_conntrack_find_get(&innertuple);
	if (!h) {
		pr_debug("icmp_error_message: no match\n");
		return -NF_ACCEPT;
	}

	if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
		*ctinfo += IP_CT_IS_REPLY;

	/* Update skb to refer to this connection */
	skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
	skb->nfctinfo = *ctinfo;
	return -NF_ACCEPT;
}

static unsigned int
nf_nat_fn(unsigned int hooknum,
	  struct sk_buff *skb,
	  const struct net_device *in,
	  const struct net_device *out,
	  int (*okfn)(struct sk_buff *))
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	struct nf_conn_nat *nat;
	/* maniptype == SRC for postrouting. */
	enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum);

	/* We never see fragments: conntrack defrags on pre-routing
	   and local-out, and nf_nat_out protects post-routing. */
	NF_CT_ASSERT(!(ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)));

	ct = nf_ct_get(skb, &ctinfo);
	/* Can't track?  It's not due to stress, or conntrack would
	   have dropped it.  Hence it's the user's responsibilty to
	   packet filter it out, or implement conntrack/NAT for that
	   protocol. 8) --RR */
	if (!ct) {
		/* Exception: ICMP redirect to new connection (not in
		   hash table yet).  We must not let this through, in
		   case we're doing NAT to the same network. */
		if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
			struct icmphdr _hdr, *hp;

			hp = skb_header_pointer(skb, ip_hdrlen(skb),
						sizeof(_hdr), &_hdr);
			if (hp != NULL &&
			    hp->type == ICMP_REDIRECT)
				return NF_DROP;
		}
		return NF_ACCEPT;
	}

	/* Don't try to NAT if this packet is not conntracked */
	if (ct == &nf_conntrack_untracked)
		return NF_ACCEPT;

	nat = nfct_nat(ct);
	if (!nat)
		return NF_ACCEPT;

	switch (ctinfo) {
	case IP_CT_RELATED:
	case IP_CT_RELATED+IP_CT_IS_REPLY:
		if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
			if (!nf_nat_icmp_reply_translation(ct, ctinfo,
							   hooknum, skb))
				return NF_DROP;
			else
				return NF_ACCEPT;
		}
		/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
	case IP_CT_NEW:

		/* Seen it before?  This can happen for loopback, retrans,
		   or local packets.. */
		if (!nf_nat_initialized(ct, maniptype)) {
			unsigned int ret;

			if (unlikely(nf_ct_is_confirmed(ct)))
				/* NAT module was loaded late */
				ret = alloc_null_binding_confirmed(ct, hooknum);
			else if (hooknum == NF_IP_LOCAL_IN)
				/* LOCAL_IN hook doesn't have a chain!  */
				ret = alloc_null_binding(ct, hooknum);
			else
				ret = nf_nat_rule_find(skb, hooknum, in, out,
						       ct);

			if (ret != NF_ACCEPT) {
				return ret;
			}

			ipt_cone_place_in_hashes(ct);
			
		} else
			DEBUGP("Already setup manip %s for ct %p\n",
			       maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
			       ct);
		break;

	default:
		/* ESTABLISHED */
		NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
			     ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
	}

	return nf_nat_packet(ct, ctinfo, hooknum, skb);
}

int nf_nat_icmp_reply_translation(struct sk_buff *skb,
				  struct nf_conn *ct,
				  enum ip_conntrack_info ctinfo,
				  unsigned int hooknum)
{
	struct {
		struct icmphdr	icmp;
		struct iphdr	ip;
	} *inside;
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
	unsigned int hdrlen = ip_hdrlen(skb);
	const struct nf_nat_l4proto *l4proto;
	struct nf_conntrack_tuple target;
	unsigned long statusbit;

	NF_CT_ASSERT(ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY);

	if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
		return 0;
	if (nf_ip_checksum(skb, hooknum, hdrlen, 0))
		return 0;

	inside = (void *)skb->data + hdrlen;
	if (inside->icmp.type == ICMP_REDIRECT) {
		if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
			return 0;
		if (ct->status & IPS_NAT_MASK)
			return 0;
	}

	if (manip == NF_NAT_MANIP_SRC)
		statusbit = IPS_SRC_NAT;
	else
		statusbit = IPS_DST_NAT;

	/* Invert if this is reply direction */
	if (dir == IP_CT_DIR_REPLY)
		statusbit ^= IPS_NAT_MASK;

	if (!(ct->status & statusbit))
		return 1;

	l4proto = __nf_nat_l4proto_find(NFPROTO_IPV4, inside->ip.protocol);
	if (!nf_nat_ipv4_manip_pkt(skb, hdrlen + sizeof(inside->icmp),
				   l4proto, &ct->tuplehash[!dir].tuple, !manip))
		return 0;

	if (skb->ip_summed != CHECKSUM_PARTIAL) {
		/* Reloading "inside" here since manip_pkt may reallocate */
		inside = (void *)skb->data + hdrlen;
		inside->icmp.checksum = 0;
		inside->icmp.checksum =
			csum_fold(skb_checksum(skb, hdrlen,
					       skb->len - hdrlen, 0));
	}

	/* Change outer to look like the reply to an incoming packet */
	nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
	l4proto = __nf_nat_l4proto_find(NFPROTO_IPV4, 0);
	if (!nf_nat_ipv4_manip_pkt(skb, 0, l4proto, &target, manip))
		return 0;

	return 1;
}

unsigned int
nf_nat_ipv4_fn(void *priv, struct sk_buff *skb,
	       const struct nf_hook_state *state,
	       unsigned int (*do_chain)(void *priv,
					struct sk_buff *skb,
					const struct nf_hook_state *state,
					struct nf_conn *ct))
{
	struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	struct nf_conn_nat *nat;
	/* maniptype == SRC for postrouting. */
	enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);

	/* We never see fragments: conntrack defrags on pre-routing
	 * and local-out, and nf_nat_out protects post-routing.
	 */
	NF_CT_ASSERT(!ip_is_fragment(ip_hdr(skb)));

	ct = nf_ct_get(skb, &ctinfo);
	/* Can't track?  It's not due to stress, or conntrack would
	 * have dropped it.  Hence it's the user's responsibilty to
	 * packet filter it out, or implement conntrack/NAT for that
	 * protocol. 8) --RR
	 */
	if (!ct)
		return NF_ACCEPT;

	/* Don't try to NAT if this packet is not conntracked */
	if (nf_ct_is_untracked(ct))
		return NF_ACCEPT;

	nat = nf_ct_nat_ext_add(ct);
	if (nat == NULL)
		return NF_ACCEPT;

	switch (ctinfo) {
	case IP_CT_RELATED:
	case IP_CT_RELATED_REPLY:
		if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
			if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
							   state->hook))
				return NF_DROP;
			else
				return NF_ACCEPT;
		}
		/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
	case IP_CT_NEW:
		/* Seen it before?  This can happen for loopback, retrans,
		 * or local packets.
		 */
		if (!nf_nat_initialized(ct, maniptype)) {
			unsigned int ret;

			ret = do_chain(priv, skb, state, ct);
			if (ret != NF_ACCEPT)
				return ret;

			if (nf_nat_initialized(ct, HOOK2MANIP(state->hook)))
				break;

			ret = nf_nat_alloc_null_binding(ct, state->hook);
			if (ret != NF_ACCEPT)
				return ret;
		} else {
			pr_debug("Already setup manip %s for ct %p\n",
				 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
				 ct);
			if (nf_nat_oif_changed(state->hook, ctinfo, nat,
					       state->out))
				goto oif_changed;
		}
		break;

	default:
		/* ESTABLISHED */
		NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
			     ctinfo == IP_CT_ESTABLISHED_REPLY);
		if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
			goto oif_changed;
	}

	return nf_nat_packet(ct, ctinfo, state->hook, skb);

oif_changed:
	nf_ct_kill_acct(ct, ctinfo, skb);
	return NF_DROP;
}

int nf_nat_icmpv6_reply_translation(struct sk_buff *skb,
				    struct nf_conn *ct,
				    enum ip_conntrack_info ctinfo,
				    unsigned int hooknum,
				    unsigned int hdrlen)
{
	struct {
		struct icmp6hdr	icmp6;
		struct ipv6hdr	ip6;
	} *inside;
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
	const struct nf_nat_l4proto *l4proto;
	struct nf_conntrack_tuple target;
	unsigned long statusbit;

	NF_CT_ASSERT(ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY);

	if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
		return 0;
	if (nf_ip6_checksum(skb, hooknum, hdrlen, IPPROTO_ICMPV6))
		return 0;

	inside = (void *)skb->data + hdrlen;
	if (inside->icmp6.icmp6_type == NDISC_REDIRECT) {
		if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
			return 0;
		if (ct->status & IPS_NAT_MASK)
			return 0;
	}

	if (manip == NF_NAT_MANIP_SRC)
		statusbit = IPS_SRC_NAT;
	else
		statusbit = IPS_DST_NAT;

	/* Invert if this is reply direction */
	if (dir == IP_CT_DIR_REPLY)
		statusbit ^= IPS_NAT_MASK;

	if (!(ct->status & statusbit))
		return 1;

	l4proto = __nf_nat_l4proto_find(NFPROTO_IPV6, inside->ip6.nexthdr);
	if (!nf_nat_ipv6_manip_pkt(skb, hdrlen + sizeof(inside->icmp6),
				   l4proto, &ct->tuplehash[!dir].tuple, !manip))
		return 0;

	if (skb->ip_summed != CHECKSUM_PARTIAL) {
		struct ipv6hdr *ipv6h = ipv6_hdr(skb);
		inside = (void *)skb->data + hdrlen;
		inside->icmp6.icmp6_cksum = 0;
		inside->icmp6.icmp6_cksum =
			csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
					skb->len - hdrlen, IPPROTO_ICMPV6,
					csum_partial(&inside->icmp6,
						     skb->len - hdrlen, 0));
	}

	nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
	l4proto = __nf_nat_l4proto_find(NFPROTO_IPV6, IPPROTO_ICMPV6);
	if (!nf_nat_ipv6_manip_pkt(skb, 0, l4proto, &target, manip))
		return 0;

	return 1;
}