/*
   *	common UDP/RAW code

   *	Linux INET6 implementation

   *
   *	Authors:

   *	Pedro Roque		<roque@di.fc.ul.pt>

   *

   *	This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   */

  #include <linux/capability.h>

  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/interrupt.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/in6.h>
  #include <linux/ipv6.h>
  #include <linux/route.h>

  #include <linux/slab.h>

  #include <linux/export.h>

  
  #include <net/ipv6.h>
  #include <net/ndisc.h>
  #include <net/addrconf.h>
  #include <net/transp_v6.h>
  #include <net/ip6_route.h>

  #include <net/tcp_states.h>

  #include <net/dsfield.h>

  
  #include <linux/errqueue.h>

  #include <linux/uaccess.h>

  static bool ipv6_mapped_addr_any(const struct in6_addr *a)

  {

  	return ipv6_addr_v4mapped(a) && (a->s6_addr32[3] == 0);

  }

  static void ip6_datagram_flow_key_init(struct flowi6 *fl6, struct sock *sk)
  {
  	struct inet_sock *inet = inet_sk(sk);
  	struct ipv6_pinfo *np = inet6_sk(sk);
  
  	memset(fl6, 0, sizeof(*fl6));
  	fl6->flowi6_proto = sk->sk_protocol;
  	fl6->daddr = sk->sk_v6_daddr;
  	fl6->saddr = np->saddr;
  	fl6->flowi6_oif = sk->sk_bound_dev_if;
  	fl6->flowi6_mark = sk->sk_mark;
  	fl6->fl6_dport = inet->inet_dport;
  	fl6->fl6_sport = inet->inet_sport;
  	fl6->flowlabel = np->flow_label;

  	fl6->flowi6_uid = sk->sk_uid;

  
  	if (!fl6->flowi6_oif)
  		fl6->flowi6_oif = np->sticky_pktinfo.ipi6_ifindex;
  
  	if (!fl6->flowi6_oif && ipv6_addr_is_multicast(&fl6->daddr))
  		fl6->flowi6_oif = np->mcast_oif;
  
  	security_sk_classify_flow(sk, flowi6_to_flowi(fl6));
  }

  int ip6_datagram_dst_update(struct sock *sk, bool fix_sk_saddr)

  {
  	struct ip6_flowlabel *flowlabel = NULL;
  	struct in6_addr *final_p, final;
  	struct ipv6_txoptions *opt;
  	struct dst_entry *dst;
  	struct inet_sock *inet = inet_sk(sk);
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct flowi6 fl6;
  	int err = 0;
  
  	if (np->sndflow && (np->flow_label & IPV6_FLOWLABEL_MASK)) {
  		flowlabel = fl6_sock_lookup(sk, np->flow_label);
  		if (!flowlabel)
  			return -EINVAL;
  	}
  	ip6_datagram_flow_key_init(&fl6, sk);
  
  	rcu_read_lock();
  	opt = flowlabel ? flowlabel->opt : rcu_dereference(np->opt);
  	final_p = fl6_update_dst(&fl6, opt, &final);
  	rcu_read_unlock();
  
  	dst = ip6_dst_lookup_flow(sk, &fl6, final_p);
  	if (IS_ERR(dst)) {
  		err = PTR_ERR(dst);
  		goto out;
  	}

  	if (fix_sk_saddr) {
  		if (ipv6_addr_any(&np->saddr))
  			np->saddr = fl6.saddr;

  		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr)) {
  			sk->sk_v6_rcv_saddr = fl6.saddr;
  			inet->inet_rcv_saddr = LOOPBACK4_IPV6;
  			if (sk->sk_prot->rehash)
  				sk->sk_prot->rehash(sk);
  		}

  	}
  
  	ip6_dst_store(sk, dst,
  		      ipv6_addr_equal(&fl6.daddr, &sk->sk_v6_daddr) ?
  		      &sk->sk_v6_daddr : NULL,
  #ifdef CONFIG_IPV6_SUBTREES
  		      ipv6_addr_equal(&fl6.saddr, &np->saddr) ?
  		      &np->saddr :
  #endif
  		      NULL);
  
  out:
  	fl6_sock_release(flowlabel);
  	return err;
  }

  void ip6_datagram_release_cb(struct sock *sk)
  {
  	struct dst_entry *dst;
  
  	if (ipv6_addr_v4mapped(&sk->sk_v6_daddr))
  		return;
  
  	rcu_read_lock();
  	dst = __sk_dst_get(sk);
  	if (!dst || !dst->obsolete ||
  	    dst->ops->check(dst, inet6_sk(sk)->dst_cookie)) {
  		rcu_read_unlock();
  		return;
  	}
  	rcu_read_unlock();
  
  	ip6_datagram_dst_update(sk, false);
  }
  EXPORT_SYMBOL_GPL(ip6_datagram_release_cb);

  int __ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr,
  			   int addr_len)

  {
  	struct sockaddr_in6	*usin = (struct sockaddr_in6 *) uaddr;

  	struct inet_sock	*inet = inet_sk(sk);
  	struct ipv6_pinfo	*np = inet6_sk(sk);

  	struct in6_addr		*daddr, old_daddr;
  	__be32			fl6_flowlabel = 0;
  	__be32			old_fl6_flowlabel;

  	__be16			old_dport;

  	int			addr_type;
  	int			err;
  
  	if (usin->sin6_family == AF_INET) {
  		if (__ipv6_only_sock(sk))
  			return -EAFNOSUPPORT;

  		err = __ip4_datagram_connect(sk, uaddr, addr_len);

  		goto ipv4_connected;
  	}
  
  	if (addr_len < SIN6_LEN_RFC2133)

  		return -EINVAL;

  	if (usin->sin6_family != AF_INET6)
  		return -EAFNOSUPPORT;

  	if (np->sndflow)

  		fl6_flowlabel = usin->sin6_flowinfo & IPV6_FLOWINFO_MASK;

  	if (ipv6_addr_any(&usin->sin6_addr)) {

  		/*
  		 *	connect to self
  		 */

  		if (ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
  			ipv6_addr_set_v4mapped(htonl(INADDR_LOOPBACK),
  					       &usin->sin6_addr);
  		else
  			usin->sin6_addr = in6addr_loopback;

  	}

  	addr_type = ipv6_addr_type(&usin->sin6_addr);

  	daddr = &usin->sin6_addr;

  	if (addr_type & IPV6_ADDR_MAPPED) {

  		struct sockaddr_in sin;
  
  		if (__ipv6_only_sock(sk)) {
  			err = -ENETUNREACH;
  			goto out;
  		}
  		sin.sin_family = AF_INET;
  		sin.sin_addr.s_addr = daddr->s6_addr32[3];
  		sin.sin_port = usin->sin6_port;

  		err = __ip4_datagram_connect(sk,
  					     (struct sockaddr *) &sin,
  					     sizeof(sin));

  
  ipv4_connected:
  		if (err)
  			goto out;

  		ipv6_addr_set_v4mapped(inet->inet_daddr, &sk->sk_v6_daddr);

  		if (ipv6_addr_any(&np->saddr) ||
  		    ipv6_mapped_addr_any(&np->saddr))

  			ipv6_addr_set_v4mapped(inet->inet_saddr, &np->saddr);

  		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr) ||
  		    ipv6_mapped_addr_any(&sk->sk_v6_rcv_saddr)) {

  			ipv6_addr_set_v4mapped(inet->inet_rcv_saddr,

  					       &sk->sk_v6_rcv_saddr);

  			if (sk->sk_prot->rehash)
  				sk->sk_prot->rehash(sk);
  		}

  		goto out;
  	}

  	if (__ipv6_addr_needs_scope_id(addr_type)) {

  		if (addr_len >= sizeof(struct sockaddr_in6) &&
  		    usin->sin6_scope_id) {
  			if (sk->sk_bound_dev_if &&
  			    sk->sk_bound_dev_if != usin->sin6_scope_id) {
  				err = -EINVAL;
  				goto out;
  			}
  			sk->sk_bound_dev_if = usin->sin6_scope_id;

  		}

  		if (!sk->sk_bound_dev_if && (addr_type & IPV6_ADDR_MULTICAST))
  			sk->sk_bound_dev_if = np->mcast_oif;

  		/* Connect to link-local address requires an interface */
  		if (!sk->sk_bound_dev_if) {
  			err = -EINVAL;
  			goto out;
  		}
  	}

  	/* save the current peer information before updating it */
  	old_daddr = sk->sk_v6_daddr;
  	old_fl6_flowlabel = np->flow_label;
  	old_dport = inet->inet_dport;

  	sk->sk_v6_daddr = *daddr;

  	np->flow_label = fl6_flowlabel;

  	inet->inet_dport = usin->sin6_port;

  
  	/*
  	 *	Check for a route to destination an obtain the
  	 *	destination cache for it.
  	 */

  	err = ip6_datagram_dst_update(sk, true);

  	if (err) {

  		/* Restore the socket peer info, to keep it consistent with
  		 * the old socket state

  		 */

  		sk->sk_v6_daddr = old_daddr;
  		np->flow_label = old_fl6_flowlabel;
  		inet->inet_dport = old_dport;

  		goto out;

  	}

  
  	sk->sk_state = TCP_ESTABLISHED;

  	sk_set_txhash(sk);

  out:

  	return err;
  }

  EXPORT_SYMBOL_GPL(__ip6_datagram_connect);

  
  int ip6_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  {
  	int res;
  
  	lock_sock(sk);
  	res = __ip6_datagram_connect(sk, uaddr, addr_len);
  	release_sock(sk);
  	return res;
  }

  EXPORT_SYMBOL_GPL(ip6_datagram_connect);

  int ip6_datagram_connect_v6_only(struct sock *sk, struct sockaddr *uaddr,
  				 int addr_len)
  {
  	DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, uaddr);
  	if (sin6->sin6_family != AF_INET6)
  		return -EAFNOSUPPORT;
  	return ip6_datagram_connect(sk, uaddr, addr_len);
  }
  EXPORT_SYMBOL_GPL(ip6_datagram_connect_v6_only);

  void ipv6_icmp_error(struct sock *sk, struct sk_buff *skb, int err,

  		     __be16 port, u32 info, u8 *payload)

  {
  	struct ipv6_pinfo *np  = inet6_sk(sk);

  	struct icmp6hdr *icmph = icmp6_hdr(skb);

  	struct sock_exterr_skb *serr;
  
  	if (!np->recverr)
  		return;
  
  	skb = skb_clone(skb, GFP_ATOMIC);
  	if (!skb)
  		return;

  	skb->protocol = htons(ETH_P_IPV6);

  	serr = SKB_EXT_ERR(skb);
  	serr->ee.ee_errno = err;
  	serr->ee.ee_origin = SO_EE_ORIGIN_ICMP6;

  	serr->ee.ee_type = icmph->icmp6_type;

  	serr->ee.ee_code = icmph->icmp6_code;
  	serr->ee.ee_pad = 0;
  	serr->ee.ee_info = info;
  	serr->ee.ee_data = 0;

  	serr->addr_offset = (u8 *)&(((struct ipv6hdr *)(icmph + 1))->daddr) -
  				  skb_network_header(skb);

  	serr->port = port;

  	__skb_pull(skb, payload - skb->data);

  	skb_reset_transport_header(skb);

  
  	if (sock_queue_err_skb(sk, skb))
  		kfree_skb(skb);
  }

  void ipv6_local_error(struct sock *sk, int err, struct flowi6 *fl6, u32 info)

  {

  	const struct ipv6_pinfo *np = inet6_sk(sk);

  	struct sock_exterr_skb *serr;
  	struct ipv6hdr *iph;
  	struct sk_buff *skb;
  
  	if (!np->recverr)
  		return;
  
  	skb = alloc_skb(sizeof(struct ipv6hdr), GFP_ATOMIC);
  	if (!skb)
  		return;

  	skb->protocol = htons(ETH_P_IPV6);

  	skb_put(skb, sizeof(struct ipv6hdr));
  	skb_reset_network_header(skb);

  	iph = ipv6_hdr(skb);

  	iph->daddr = fl6->daddr;

  	ip6_flow_hdr(iph, 0, 0);

  
  	serr = SKB_EXT_ERR(skb);
  	serr->ee.ee_errno = err;
  	serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;

  	serr->ee.ee_type = 0;

  	serr->ee.ee_code = 0;
  	serr->ee.ee_pad = 0;
  	serr->ee.ee_info = info;
  	serr->ee.ee_data = 0;

  	serr->addr_offset = (u8 *)&iph->daddr - skb_network_header(skb);

  	serr->port = fl6->fl6_dport;

  	__skb_pull(skb, skb_tail_pointer(skb) - skb->data);

  	skb_reset_transport_header(skb);

  
  	if (sock_queue_err_skb(sk, skb))
  		kfree_skb(skb);
  }

  void ipv6_local_rxpmtu(struct sock *sk, struct flowi6 *fl6, u32 mtu)

  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct ipv6hdr *iph;
  	struct sk_buff *skb;
  	struct ip6_mtuinfo *mtu_info;
  
  	if (!np->rxopt.bits.rxpmtu)
  		return;
  
  	skb = alloc_skb(sizeof(struct ipv6hdr), GFP_ATOMIC);
  	if (!skb)
  		return;
  
  	skb_put(skb, sizeof(struct ipv6hdr));
  	skb_reset_network_header(skb);
  	iph = ipv6_hdr(skb);

  	iph->daddr = fl6->daddr;

  
  	mtu_info = IP6CBMTU(skb);

  
  	mtu_info->ip6m_mtu = mtu;
  	mtu_info->ip6m_addr.sin6_family = AF_INET6;
  	mtu_info->ip6m_addr.sin6_port = 0;
  	mtu_info->ip6m_addr.sin6_flowinfo = 0;

  	mtu_info->ip6m_addr.sin6_scope_id = fl6->flowi6_oif;

  	mtu_info->ip6m_addr.sin6_addr = ipv6_hdr(skb)->daddr;

  
  	__skb_pull(skb, skb_tail_pointer(skb) - skb->data);
  	skb_reset_transport_header(skb);
  
  	skb = xchg(&np->rxpmtu, skb);
  	kfree_skb(skb);
  }

  /* For some errors we have valid addr_offset even with zero payload and
   * zero port. Also, addr_offset should be supported if port is set.
   */
  static inline bool ipv6_datagram_support_addr(struct sock_exterr_skb *serr)
  {
  	return serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6 ||
  	       serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
  	       serr->ee.ee_origin == SO_EE_ORIGIN_LOCAL || serr->port;
  }

  /* IPv6 supports cmsg on all origins aside from SO_EE_ORIGIN_LOCAL.
   *
   * At one point, excluding local errors was a quick test to identify icmp/icmp6
   * errors. This is no longer true, but the test remained, so the v6 stack,
   * unlike v4, also honors cmsg requests on all wifi and timestamp errors.

   */
  static bool ip6_datagram_support_cmsg(struct sk_buff *skb,
  				      struct sock_exterr_skb *serr)

  {

  	if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP ||
  	    serr->ee.ee_origin == SO_EE_ORIGIN_ICMP6)
  		return true;
  
  	if (serr->ee.ee_origin == SO_EE_ORIGIN_LOCAL)
  		return false;

  	if (!IP6CB(skb)->iif)

  		return false;

  	return true;

  }

  /*

   *	Handle MSG_ERRQUEUE
   */

  int ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)

  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct sock_exterr_skb *serr;

  	struct sk_buff *skb;

  	DECLARE_SOCKADDR(struct sockaddr_in6 *, sin, msg->msg_name);

  	struct {
  		struct sock_extended_err ee;
  		struct sockaddr_in6	 offender;
  	} errhdr;
  	int err;
  	int copied;
  
  	err = -EAGAIN;

  	skb = sock_dequeue_err_skb(sk);

  	if (!skb)

  		goto out;
  
  	copied = skb->len;
  	if (copied > len) {
  		msg->msg_flags |= MSG_TRUNC;
  		copied = len;
  	}

  	err = skb_copy_datagram_msg(skb, 0, msg, copied);

  	if (unlikely(err)) {
  		kfree_skb(skb);
  		return err;
  	}

  	sock_recv_timestamp(msg, sk, skb);
  
  	serr = SKB_EXT_ERR(skb);

  	if (sin && ipv6_datagram_support_addr(serr)) {

  		const unsigned char *nh = skb_network_header(skb);

  		sin->sin6_family = AF_INET6;
  		sin->sin6_flowinfo = 0;

  		sin->sin6_port = serr->port;

  		if (skb->protocol == htons(ETH_P_IPV6)) {

  			const struct ipv6hdr *ip6h = container_of((struct in6_addr *)(nh + serr->addr_offset),
  								  struct ipv6hdr, daddr);
  			sin->sin6_addr = ip6h->daddr;

  			if (np->sndflow)

  				sin->sin6_flowinfo = ip6_flowinfo(ip6h);

  			sin->sin6_scope_id =
  				ipv6_iface_scope_id(&sin->sin6_addr,
  						    IP6CB(skb)->iif);

  		} else {

  			ipv6_addr_set_v4mapped(*(__be32 *)(nh + serr->addr_offset),
  					       &sin->sin6_addr);

  			sin->sin6_scope_id = 0;

  		}

  		*addr_len = sizeof(*sin);

  	}
  
  	memcpy(&errhdr.ee, &serr->ee, sizeof(struct sock_extended_err));
  	sin = &errhdr.offender;

  	memset(sin, 0, sizeof(*sin));

  
  	if (ip6_datagram_support_cmsg(skb, serr)) {

  		sin->sin6_family = AF_INET6;

  		if (np->rxopt.all)

  			ip6_datagram_recv_common_ctl(sk, msg, skb);

  		if (skb->protocol == htons(ETH_P_IPV6)) {

  			sin->sin6_addr = ipv6_hdr(skb)->saddr;

  			if (np->rxopt.all)

  				ip6_datagram_recv_specific_ctl(sk, msg, skb);

  			sin->sin6_scope_id =
  				ipv6_iface_scope_id(&sin->sin6_addr,
  						    IP6CB(skb)->iif);

  		} else {

  			ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr,
  					       &sin->sin6_addr);

  			if (inet_sk(sk)->cmsg_flags)

  				ip_cmsg_recv(msg, skb);
  		}
  	}
  
  	put_cmsg(msg, SOL_IPV6, IPV6_RECVERR, sizeof(errhdr), &errhdr);
  
  	/* Now we could try to dump offended packet options */
  
  	msg->msg_flags |= MSG_ERRQUEUE;
  	err = copied;

  	consume_skb(skb);

  out:
  	return err;
  }

  EXPORT_SYMBOL_GPL(ipv6_recv_error);

  /*
   *	Handle IPV6_RECVPATHMTU
   */

  int ipv6_recv_rxpmtu(struct sock *sk, struct msghdr *msg, int len,
  		     int *addr_len)

  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct sk_buff *skb;

  	struct ip6_mtuinfo mtu_info;

  	DECLARE_SOCKADDR(struct sockaddr_in6 *, sin, msg->msg_name);

  	int err;
  	int copied;
  
  	err = -EAGAIN;
  	skb = xchg(&np->rxpmtu, NULL);

  	if (!skb)

  		goto out;
  
  	copied = skb->len;
  	if (copied > len) {
  		msg->msg_flags |= MSG_TRUNC;
  		copied = len;
  	}

  	err = skb_copy_datagram_msg(skb, 0, msg, copied);

  	if (err)
  		goto out_free_skb;
  
  	sock_recv_timestamp(msg, sk, skb);
  
  	memcpy(&mtu_info, IP6CBMTU(skb), sizeof(mtu_info));

  	if (sin) {
  		sin->sin6_family = AF_INET6;
  		sin->sin6_flowinfo = 0;
  		sin->sin6_port = 0;
  		sin->sin6_scope_id = mtu_info.ip6m_addr.sin6_scope_id;

  		sin->sin6_addr = mtu_info.ip6m_addr.sin6_addr;

  		*addr_len = sizeof(*sin);

  	}
  
  	put_cmsg(msg, SOL_IPV6, IPV6_PATHMTU, sizeof(mtu_info), &mtu_info);
  
  	err = copied;
  
  out_free_skb:
  	kfree_skb(skb);
  out:
  	return err;
  }

  void ip6_datagram_recv_common_ctl(struct sock *sk, struct msghdr *msg,
  				 struct sk_buff *skb)

  {
  	struct ipv6_pinfo *np = inet6_sk(sk);

  	bool is_ipv6 = skb->protocol == htons(ETH_P_IPV6);

  
  	if (np->rxopt.bits.rxinfo) {
  		struct in6_pktinfo src_info;

  		if (is_ipv6) {
  			src_info.ipi6_ifindex = IP6CB(skb)->iif;
  			src_info.ipi6_addr = ipv6_hdr(skb)->daddr;
  		} else {
  			src_info.ipi6_ifindex =
  				PKTINFO_SKB_CB(skb)->ipi_ifindex;
  			ipv6_addr_set_v4mapped(ip_hdr(skb)->daddr,
  					       &src_info.ipi6_addr);
  		}

  
  		if (src_info.ipi6_ifindex >= 0)
  			put_cmsg(msg, SOL_IPV6, IPV6_PKTINFO,
  				 sizeof(src_info), &src_info);

  	}

  }
  
  void ip6_datagram_recv_specific_ctl(struct sock *sk, struct msghdr *msg,
  				    struct sk_buff *skb)
  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct inet6_skb_parm *opt = IP6CB(skb);
  	unsigned char *nh = skb_network_header(skb);

  
  	if (np->rxopt.bits.rxhlim) {

  		int hlim = ipv6_hdr(skb)->hop_limit;

  		put_cmsg(msg, SOL_IPV6, IPV6_HOPLIMIT, sizeof(hlim), &hlim);
  	}

  	if (np->rxopt.bits.rxtclass) {

  		int tclass = ipv6_get_dsfield(ipv6_hdr(skb));

  		put_cmsg(msg, SOL_IPV6, IPV6_TCLASS, sizeof(tclass), &tclass);
  	}

  	if (np->rxopt.bits.rxflow) {
  		__be32 flowinfo = ip6_flowinfo((struct ipv6hdr *)nh);
  		if (flowinfo)
  			put_cmsg(msg, SOL_IPV6, IPV6_FLOWINFO, sizeof(flowinfo), &flowinfo);

  	}

  
  	/* HbH is allowed only once */

  	if (np->rxopt.bits.hopopts && (opt->flags & IP6SKB_HOPBYHOP)) {
  		u8 *ptr = nh + sizeof(struct ipv6hdr);

  		put_cmsg(msg, SOL_IPV6, IPV6_HOPOPTS, (ptr[1]+1)<<3, ptr);
  	}

  
  	if (opt->lastopt &&
  	    (np->rxopt.bits.dstopts || np->rxopt.bits.srcrt)) {
  		/*
  		 * Silly enough, but we need to reparse in order to
  		 * report extension headers (except for HbH)
  		 * in order.
  		 *

  		 * Also note that IPV6_RECVRTHDRDSTOPTS is NOT

  		 * (and WILL NOT be) defined because
  		 * IPV6_RECVDSTOPTS is more generic. --yoshfuji
  		 */
  		unsigned int off = sizeof(struct ipv6hdr);

  		u8 nexthdr = ipv6_hdr(skb)->nexthdr;

  
  		while (off <= opt->lastopt) {

  			unsigned int len;

  			u8 *ptr = nh + off;

  			switch (nexthdr) {

  			case IPPROTO_DSTOPTS:
  				nexthdr = ptr[0];
  				len = (ptr[1] + 1) << 3;
  				if (np->rxopt.bits.dstopts)
  					put_cmsg(msg, SOL_IPV6, IPV6_DSTOPTS, len, ptr);
  				break;
  			case IPPROTO_ROUTING:
  				nexthdr = ptr[0];
  				len = (ptr[1] + 1) << 3;
  				if (np->rxopt.bits.srcrt)
  					put_cmsg(msg, SOL_IPV6, IPV6_RTHDR, len, ptr);
  				break;
  			case IPPROTO_AH:
  				nexthdr = ptr[0];

  				len = (ptr[1] + 2) << 2;

  				break;
  			default:
  				nexthdr = ptr[0];
  				len = (ptr[1] + 1) << 3;
  				break;
  			}
  
  			off += len;
  		}
  	}
  
  	/* socket options in old style */
  	if (np->rxopt.bits.rxoinfo) {
  		struct in6_pktinfo src_info;
  
  		src_info.ipi6_ifindex = opt->iif;

  		src_info.ipi6_addr = ipv6_hdr(skb)->daddr;

  		put_cmsg(msg, SOL_IPV6, IPV6_2292PKTINFO, sizeof(src_info), &src_info);
  	}
  	if (np->rxopt.bits.rxohlim) {

  		int hlim = ipv6_hdr(skb)->hop_limit;

  		put_cmsg(msg, SOL_IPV6, IPV6_2292HOPLIMIT, sizeof(hlim), &hlim);
  	}

  	if (np->rxopt.bits.ohopopts && (opt->flags & IP6SKB_HOPBYHOP)) {
  		u8 *ptr = nh + sizeof(struct ipv6hdr);

  		put_cmsg(msg, SOL_IPV6, IPV6_2292HOPOPTS, (ptr[1]+1)<<3, ptr);
  	}
  	if (np->rxopt.bits.odstopts && opt->dst0) {

  		u8 *ptr = nh + opt->dst0;

  		put_cmsg(msg, SOL_IPV6, IPV6_2292DSTOPTS, (ptr[1]+1)<<3, ptr);

  	}

  	if (np->rxopt.bits.osrcrt && opt->srcrt) {

  		struct ipv6_rt_hdr *rthdr = (struct ipv6_rt_hdr *)(nh + opt->srcrt);

  		put_cmsg(msg, SOL_IPV6, IPV6_2292RTHDR, (rthdr->hdrlen+1) << 3, rthdr);

  	}

  	if (np->rxopt.bits.odstopts && opt->dst1) {

  		u8 *ptr = nh + opt->dst1;

  		put_cmsg(msg, SOL_IPV6, IPV6_2292DSTOPTS, (ptr[1]+1)<<3, ptr);

  	}

  	if (np->rxopt.bits.rxorigdstaddr) {
  		struct sockaddr_in6 sin6;

  		__be16 _ports[2], *ports;

  		ports = skb_header_pointer(skb, skb_transport_offset(skb),
  					   sizeof(_ports), &_ports);
  		if (ports) {

  			/* All current transport protocols have the port numbers in the
  			 * first four bytes of the transport header and this function is
  			 * written with this assumption in mind.
  			 */

  			sin6.sin6_family = AF_INET6;

  			sin6.sin6_addr = ipv6_hdr(skb)->daddr;

  			sin6.sin6_port = ports[1];
  			sin6.sin6_flowinfo = 0;

  			sin6.sin6_scope_id =
  				ipv6_iface_scope_id(&ipv6_hdr(skb)->daddr,
  						    opt->iif);

  
  			put_cmsg(msg, SOL_IPV6, IPV6_ORIGDSTADDR, sizeof(sin6), &sin6);
  		}
  	}

  	if (np->rxopt.bits.recvfragsize && opt->frag_max_size) {
  		int val = opt->frag_max_size;
  
  		put_cmsg(msg, SOL_IPV6, IPV6_RECVFRAGSIZE, sizeof(val), &val);
  	}

  }
  
  void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
  			  struct sk_buff *skb)
  {
  	ip6_datagram_recv_common_ctl(sk, msg, skb);
  	ip6_datagram_recv_specific_ctl(sk, msg, skb);

  }

  EXPORT_SYMBOL_GPL(ip6_datagram_recv_ctl);

  int ip6_datagram_send_ctl(struct net *net, struct sock *sk,
  			  struct msghdr *msg, struct flowi6 *fl6,

  			  struct ipcm6_cookie *ipc6, struct sockcm_cookie *sockc)

  {
  	struct in6_pktinfo *src_info;
  	struct cmsghdr *cmsg;
  	struct ipv6_rt_hdr *rthdr;
  	struct ipv6_opt_hdr *hdr;

  	struct ipv6_txoptions *opt = ipc6->opt;

  	int len;
  	int err = 0;

  	for_each_cmsghdr(cmsg, msg) {

  		int addr_type;

  
  		if (!CMSG_OK(msg, cmsg)) {
  			err = -EINVAL;
  			goto exit_f;
  		}

  		if (cmsg->cmsg_level == SOL_SOCKET) {

  			err = __sock_cmsg_send(sk, msg, cmsg, sockc);
  			if (err)
  				return err;

  			continue;
  		}

  		if (cmsg->cmsg_level != SOL_IPV6)
  			continue;
  
  		switch (cmsg->cmsg_type) {

  		case IPV6_PKTINFO:
  		case IPV6_2292PKTINFO:

  		    {
  			struct net_device *dev = NULL;

  			if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct in6_pktinfo))) {

  				err = -EINVAL;
  				goto exit_f;
  			}
  
  			src_info = (struct in6_pktinfo *)CMSG_DATA(cmsg);

  			if (src_info->ipi6_ifindex) {

  				if (fl6->flowi6_oif &&
  				    src_info->ipi6_ifindex != fl6->flowi6_oif)

  					return -EINVAL;

  				fl6->flowi6_oif = src_info->ipi6_ifindex;

  			}

  			addr_type = __ipv6_addr_type(&src_info->ipi6_addr);

  			rcu_read_lock();

  			if (fl6->flowi6_oif) {
  				dev = dev_get_by_index_rcu(net, fl6->flowi6_oif);

  				if (!dev) {
  					rcu_read_unlock();

  					return -ENODEV;

  				}
  			} else if (addr_type & IPV6_ADDR_LINKLOCAL) {
  				rcu_read_unlock();

  				return -EINVAL;

  			}

  			if (addr_type != IPV6_ADDR_ANY) {
  				int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;

  				if (!(inet_sk(sk)->freebind || inet_sk(sk)->transparent) &&

  				    !ipv6_chk_addr(net, &src_info->ipi6_addr,

  						   strict ? dev : NULL, 0) &&
  				    !ipv6_chk_acast_addr_src(net, dev,
  							     &src_info->ipi6_addr))

  					err = -EINVAL;
  				else

  					fl6->saddr = src_info->ipi6_addr;

  			}

  			rcu_read_unlock();

  			if (err)
  				goto exit_f;

  			break;

  		    }

  
  		case IPV6_FLOWINFO:

  			if (cmsg->cmsg_len < CMSG_LEN(4)) {

  				err = -EINVAL;
  				goto exit_f;
  			}

  			if (fl6->flowlabel&IPV6_FLOWINFO_MASK) {
  				if ((fl6->flowlabel^*(__be32 *)CMSG_DATA(cmsg))&~IPV6_FLOWINFO_MASK) {

  					err = -EINVAL;
  					goto exit_f;
  				}
  			}

  			fl6->flowlabel = IPV6_FLOWINFO_MASK & *(__be32 *)CMSG_DATA(cmsg);

  			break;

  		case IPV6_2292HOPOPTS:

  		case IPV6_HOPOPTS:

  			if (opt->hopopt || cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {

  				err = -EINVAL;
  				goto exit_f;
  			}
  
  			hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
  			len = ((hdr->hdrlen + 1) << 3);
  			if (cmsg->cmsg_len < CMSG_LEN(len)) {
  				err = -EINVAL;
  				goto exit_f;
  			}

  			if (!ns_capable(net->user_ns, CAP_NET_RAW)) {

  				err = -EPERM;
  				goto exit_f;
  			}
  			opt->opt_nflen += len;
  			opt->hopopt = hdr;
  			break;

  		case IPV6_2292DSTOPTS:

  			if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {

  				err = -EINVAL;
  				goto exit_f;
  			}
  
  			hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
  			len = ((hdr->hdrlen + 1) << 3);
  			if (cmsg->cmsg_len < CMSG_LEN(len)) {
  				err = -EINVAL;
  				goto exit_f;
  			}

  			if (!ns_capable(net->user_ns, CAP_NET_RAW)) {

  				err = -EPERM;
  				goto exit_f;
  			}
  			if (opt->dst1opt) {
  				err = -EINVAL;
  				goto exit_f;
  			}
  			opt->opt_flen += len;
  			opt->dst1opt = hdr;
  			break;

  		case IPV6_DSTOPTS:
  		case IPV6_RTHDRDSTOPTS:
  			if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_opt_hdr))) {
  				err = -EINVAL;
  				goto exit_f;
  			}
  
  			hdr = (struct ipv6_opt_hdr *)CMSG_DATA(cmsg);
  			len = ((hdr->hdrlen + 1) << 3);
  			if (cmsg->cmsg_len < CMSG_LEN(len)) {
  				err = -EINVAL;
  				goto exit_f;
  			}

  			if (!ns_capable(net->user_ns, CAP_NET_RAW)) {

  				err = -EPERM;
  				goto exit_f;
  			}
  			if (cmsg->cmsg_type == IPV6_DSTOPTS) {
  				opt->opt_flen += len;
  				opt->dst1opt = hdr;
  			} else {
  				opt->opt_nflen += len;
  				opt->dst0opt = hdr;
  			}
  			break;
  
  		case IPV6_2292RTHDR:

  		case IPV6_RTHDR:

  			if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct ipv6_rt_hdr))) {

  				err = -EINVAL;
  				goto exit_f;
  			}
  
  			rthdr = (struct ipv6_rt_hdr *)CMSG_DATA(cmsg);

  			switch (rthdr->type) {

  #if IS_ENABLED(CONFIG_IPV6_MIP6)

  			case IPV6_SRCRT_TYPE_2:

  				if (rthdr->hdrlen != 2 ||
  				    rthdr->segments_left != 1) {
  					err = -EINVAL;
  					goto exit_f;
  				}

  				break;

  #endif

  			default:

  				err = -EINVAL;
  				goto exit_f;
  			}
  
  			len = ((rthdr->hdrlen + 1) << 3);

  			if (cmsg->cmsg_len < CMSG_LEN(len)) {

  				err = -EINVAL;
  				goto exit_f;
  			}
  
  			/* segments left must also match */
  			if ((rthdr->hdrlen >> 1) != rthdr->segments_left) {
  				err = -EINVAL;
  				goto exit_f;
  			}
  
  			opt->opt_nflen += len;
  			opt->srcrt = rthdr;

  			if (cmsg->cmsg_type == IPV6_2292RTHDR && opt->dst1opt) {

  				int dsthdrlen = ((opt->dst1opt->hdrlen+1)<<3);
  
  				opt->opt_nflen += dsthdrlen;
  				opt->dst0opt = opt->dst1opt;
  				opt->dst1opt = NULL;
  				opt->opt_flen -= dsthdrlen;
  			}
  
  			break;

  		case IPV6_2292HOPLIMIT:

  		case IPV6_HOPLIMIT:
  			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
  				err = -EINVAL;
  				goto exit_f;
  			}

  			ipc6->hlimit = *(int *)CMSG_DATA(cmsg);
  			if (ipc6->hlimit < -1 || ipc6->hlimit > 0xff) {

  				err = -EINVAL;
  				goto exit_f;
  			}

  			break;

  		case IPV6_TCLASS:
  		    {
  			int tc;
  
  			err = -EINVAL;

  			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))

  				goto exit_f;

  
  			tc = *(int *)CMSG_DATA(cmsg);

  			if (tc < -1 || tc > 0xff)

  				goto exit_f;
  
  			err = 0;

  			ipc6->tclass = tc;

  
  			break;
  		    }

  
  		case IPV6_DONTFRAG:
  		    {
  			int df;
  
  			err = -EINVAL;

  			if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)))

  				goto exit_f;

  
  			df = *(int *)CMSG_DATA(cmsg);
  			if (df < 0 || df > 1)
  				goto exit_f;
  
  			err = 0;

  			ipc6->dontfrag = df;

  
  			break;
  		    }

  		default:

  			net_dbg_ratelimited("invalid cmsg type: %d
  ",
  					    cmsg->cmsg_type);

  			err = -EINVAL;

  			goto exit_f;

  		}

  	}
  
  exit_f:
  	return err;
  }

  EXPORT_SYMBOL_GPL(ip6_datagram_send_ctl);

  void __ip6_dgram_sock_seq_show(struct seq_file *seq, struct sock *sp,
  			       __u16 srcp, __u16 destp, int rqueue, int bucket)

  {

  	const struct in6_addr *dest, *src;

  	dest  = &sp->sk_v6_daddr;
  	src   = &sp->sk_v6_rcv_saddr;

  	seq_printf(seq,
  		   "%5d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "

  		   "%02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d
  ",

  		   bucket,
  		   src->s6_addr32[0], src->s6_addr32[1],
  		   src->s6_addr32[2], src->s6_addr32[3], srcp,
  		   dest->s6_addr32[0], dest->s6_addr32[1],
  		   dest->s6_addr32[2], dest->s6_addr32[3], destp,
  		   sp->sk_state,
  		   sk_wmem_alloc_get(sp),

  		   rqueue,

  		   0, 0L, 0,
  		   from_kuid_munged(seq_user_ns(seq), sock_i_uid(sp)),
  		   0,
  		   sock_i_ino(sp),

  		   refcount_read(&sp->sk_refcnt), sp,

  		   atomic_read(&sp->sk_drops));
  }