// SPDX-License-Identifier: GPL-2.0-or-later

  /* SCTP kernel implementation

   * (C) Copyright IBM Corp. 2002, 2004
   * Copyright (c) 2001 Nokia, Inc.
   * Copyright (c) 2001 La Monte H.P. Yarroll
   * Copyright (c) 2002-2003 Intel Corp.
   *

   * This file is part of the SCTP kernel implementation

   *
   * SCTP over IPv6.
   *

   * Please send any bug reports or fixes you make to the
   * email address(es):

   *    lksctp developers <linux-sctp@vger.kernel.org>

   *

   * Written or modified by:
   *    Le Yanqun		    <yanqun.le@nokia.com>
   *    Hui Huang		    <hui.huang@nokia.com>
   *    La Monte H.P. Yarroll <piggy@acm.org>
   *    Sridhar Samudrala	    <sri@us.ibm.com>
   *    Jon Grimm		    <jgrimm@us.ibm.com>
   *    Ardelle Fan	    <ardelle.fan@intel.com>
   *
   * Based on:
   *	linux/net/ipv6/tcp_ipv6.c

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/net.h>

  #include <linux/in.h>
  #include <linux/in6.h>
  #include <linux/netdevice.h>
  #include <linux/init.h>
  #include <linux/ipsec.h>

  #include <linux/slab.h>

  
  #include <linux/ipv6.h>
  #include <linux/icmpv6.h>
  #include <linux/random.h>
  #include <linux/seq_file.h>
  
  #include <net/protocol.h>

  #include <net/ndisc.h>

  #include <net/ip.h>

  #include <net/ipv6.h>
  #include <net/transp_v6.h>
  #include <net/addrconf.h>
  #include <net/ip6_route.h>
  #include <net/inet_common.h>
  #include <net/inet_ecn.h>
  #include <net/sctp/sctp.h>

  #include <linux/uaccess.h>

  static inline int sctp_v6_addr_match_len(union sctp_addr *s1,
  					 union sctp_addr *s2);

  static void sctp_v6_to_addr(union sctp_addr *addr, struct in6_addr *saddr,
  			      __be16 port);
  static int sctp_v6_cmp_addr(const union sctp_addr *addr1,
  			    const union sctp_addr *addr2);

  /* Event handler for inet6 address addition/deletion events.
   * The sctp_local_addr_list needs to be protocted by a spin lock since
   * multiple notifiers (say IPv4 and IPv6) may be running at the same
   * time and thus corrupt the list.
   * The reader side is protected with RCU.
   */

  static int sctp_inet6addr_event(struct notifier_block *this, unsigned long ev,
  				void *ptr)

  {
  	struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;

  	struct sctp_sockaddr_entry *addr = NULL;
  	struct sctp_sockaddr_entry *temp;

  	struct net *net = dev_net(ifa->idev->dev);

  	int found = 0;

  
  	switch (ev) {
  	case NETDEV_UP:

  		addr = kzalloc(sizeof(*addr), GFP_ATOMIC);

  		if (addr) {
  			addr->a.v6.sin6_family = AF_INET6;

  			addr->a.v6.sin6_addr = ifa->addr;

  			addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;

  			addr->valid = 1;

  			spin_lock_bh(&net->sctp.local_addr_lock);
  			list_add_tail_rcu(&addr->list, &net->sctp.local_addr_list);
  			sctp_addr_wq_mgmt(net, addr, SCTP_ADDR_NEW);
  			spin_unlock_bh(&net->sctp.local_addr_lock);

  		}
  		break;
  	case NETDEV_DOWN:

  		spin_lock_bh(&net->sctp.local_addr_lock);

  		list_for_each_entry_safe(addr, temp,

  					&net->sctp.local_addr_list, list) {

  			if (addr->a.sa.sa_family == AF_INET6 &&
  					ipv6_addr_equal(&addr->a.v6.sin6_addr,
  						&ifa->addr)) {

  				sctp_addr_wq_mgmt(net, addr, SCTP_ADDR_DEL);

  				found = 1;

  				addr->valid = 0;
  				list_del_rcu(&addr->list);

  				break;
  			}
  		}

  		spin_unlock_bh(&net->sctp.local_addr_lock);

  		if (found)

  			kfree_rcu(addr, rcu);

  		break;
  	}
  
  	return NOTIFY_DONE;
  }

  static struct notifier_block sctp_inet6addr_notifier = {

  	.notifier_call = sctp_inet6addr_event,

  };
  
  /* ICMP error handler. */

  static int sctp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

  			u8 type, u8 code, int offset, __be32 info)

  {
  	struct inet6_dev *idev;

  	struct sock *sk;

  	struct sctp_association *asoc;
  	struct sctp_transport *transport;
  	struct ipv6_pinfo *np;

  	__u16 saveip, savesctp;

  	int err, ret = 0;

  	struct net *net = dev_net(skb->dev);

  
  	idev = in6_dev_get(skb->dev);
  
  	/* Fix up skb to look at the embedded net header. */

  	saveip	 = skb->network_header;
  	savesctp = skb->transport_header;

  	skb_reset_network_header(skb);

  	skb_set_transport_header(skb, offset);

  	sk = sctp_err_lookup(net, AF_INET6, skb, sctp_hdr(skb), &asoc, &transport);

  	/* Put back, the original pointers. */

  	skb->network_header   = saveip;
  	skb->transport_header = savesctp;

  	if (!sk) {

  		__ICMP6_INC_STATS(net, idev, ICMP6_MIB_INERRORS);

  		ret = -ENOENT;

  		goto out;
  	}
  
  	/* Warning:  The sock lock is held.  Remember to call
  	 * sctp_err_finish!
  	 */
  
  	switch (type) {
  	case ICMPV6_PKT_TOOBIG:

  		if (ip6_sk_accept_pmtu(sk))
  			sctp_icmp_frag_needed(sk, asoc, transport, ntohl(info));

  		goto out_unlock;
  	case ICMPV6_PARAMPROB:
  		if (ICMPV6_UNK_NEXTHDR == code) {

  			sctp_icmp_proto_unreachable(sk, asoc, transport);

  			goto out_unlock;
  		}
  		break;

  	case NDISC_REDIRECT:
  		sctp_icmp_redirect(sk, transport, skb);

  		goto out_unlock;

  	default:
  		break;
  	}
  
  	np = inet6_sk(sk);
  	icmpv6_err_convert(type, code, &err);
  	if (!sock_owned_by_user(sk) && np->recverr) {
  		sk->sk_err = err;
  		sk->sk_error_report(sk);
  	} else {  /* Only an error on timeout */
  		sk->sk_err_soft = err;
  	}
  
  out_unlock:

  	sctp_err_finish(sk, transport);

  out:
  	if (likely(idev != NULL))
  		in6_dev_put(idev);

  
  	return ret;

  }

  static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *transport)

  {
  	struct sock *sk = skb->sk;
  	struct ipv6_pinfo *np = inet6_sk(sk);

  	struct flowi6 *fl6 = &transport->fl.u.ip6;

  	__u8 tclass = np->tclass;

  	int res;

  	pr_debug("%s: skb:%p, len:%d, src:%pI6 dst:%pI6
  ", __func__, skb,

  		 skb->len, &fl6->saddr, &fl6->daddr);

  	if (transport->dscp & SCTP_DSCP_SET_MASK)
  		tclass = transport->dscp & SCTP_DSCP_VAL_MASK;
  
  	if (INET_ECN_is_capable(tclass))
  		IP6_ECN_flow_xmit(sk, fl6->flowlabel);

  	if (!(transport->param_flags & SPP_PMTUD_ENABLE))

  		skb->ignore_df = 1;

  	SCTP_INC_STATS(sock_net(sk), SCTP_MIB_OUTSCTPPACKS);

  	rcu_read_lock();

  	res = ip6_xmit(sk, skb, fl6, sk->sk_mark, rcu_dereference(np->opt),

  		       tclass, sk->sk_priority);

  	rcu_read_unlock();
  	return res;

  }
  
  /* Returns the dst cache entry for the given source and destination ip
   * addresses.
   */

  static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
  			    struct flowi *fl, struct sock *sk)

  {

  	struct sctp_association *asoc = t->asoc;

  	struct dst_entry *dst = NULL;

  	struct flowi6 *fl6 = &fl->u.ip6;

  	struct sctp_bind_addr *bp;

  	struct ipv6_pinfo *np = inet6_sk(sk);

  	struct sctp_sockaddr_entry *laddr;

  	union sctp_addr *daddr = &t->ipaddr;

  	union sctp_addr dst_saddr;

  	struct in6_addr *final_p, final;

  	enum sctp_scope scope;

  	__u8 matchlen = 0;

  	memset(fl6, 0, sizeof(struct flowi6));

  	fl6->daddr = daddr->v6.sin6_addr;

  	fl6->fl6_dport = daddr->v6.sin6_port;
  	fl6->flowi6_proto = IPPROTO_SCTP;

  	if (ipv6_addr_type(&daddr->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL)

  		fl6->flowi6_oif = daddr->v6.sin6_scope_id;

  	else if (asoc)
  		fl6->flowi6_oif = asoc->base.sk->sk_bound_dev_if;

  	if (t->flowlabel & SCTP_FLOWLABEL_SET_MASK)
  		fl6->flowlabel = htonl(t->flowlabel & SCTP_FLOWLABEL_VAL_MASK);

  	if (np->sndflow && (fl6->flowlabel & IPV6_FLOWLABEL_MASK)) {
  		struct ip6_flowlabel *flowlabel;
  
  		flowlabel = fl6_sock_lookup(sk, fl6->flowlabel);

  		if (IS_ERR(flowlabel))

  			goto out;
  		fl6_sock_release(flowlabel);
  	}

  	pr_debug("%s: dst=%pI6 ", __func__, &fl6->daddr);

  	if (asoc)
  		fl6->fl6_sport = htons(asoc->base.bind_addr.port);

  
  	if (saddr) {

  		fl6->saddr = saddr->v6.sin6_addr;

  		if (!fl6->fl6_sport)
  			fl6->fl6_sport = saddr->v6.sin6_port;

  
  		pr_debug("src=%pI6 - ", &fl6->saddr);

  	}

  	rcu_read_lock();
  	final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
  	rcu_read_unlock();

  	dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);

  	if (!asoc || saddr)
  		goto out;

  	bp = &asoc->base.bind_addr;
  	scope = sctp_scope(daddr);
  	/* ip6_dst_lookup has filled in the fl6->saddr for us.  Check
  	 * to see if we can use it.
  	 */

  	if (!IS_ERR(dst)) {

  		/* Walk through the bind address list and look for a bind
  		 * address that matches the source address of the returned dst.

  		 */

  		sctp_v6_to_addr(&dst_saddr, &fl6->saddr, htons(bp->port));

  		rcu_read_lock();
  		list_for_each_entry_rcu(laddr, &bp->address_list, list) {

  			if (!laddr->valid || laddr->state == SCTP_ADDR_DEL ||
  			    (laddr->state != SCTP_ADDR_SRC &&
  			     !asoc->src_out_of_asoc_ok))

  				continue;

  
  			/* Do not compare against v4 addrs */
  			if ((laddr->a.sa.sa_family == AF_INET6) &&
  			    (sctp_v6_cmp_addr(&dst_saddr, &laddr->a))) {
  				rcu_read_unlock();
  				goto out;

  			}
  		}
  		rcu_read_unlock();

  		/* None of the bound addresses match the source address of the
  		 * dst. So release it.
  		 */
  		dst_release(dst);
  		dst = NULL;

  	}

  	/* Walk through the bind address list and try to get the
  	 * best source address for a given destination.
  	 */
  	rcu_read_lock();
  	list_for_each_entry_rcu(laddr, &bp->address_list, list) {

  		struct dst_entry *bdst;
  		__u8 bmatchlen;
  
  		if (!laddr->valid ||
  		    laddr->state != SCTP_ADDR_SRC ||
  		    laddr->a.sa.sa_family != AF_INET6 ||
  		    scope > sctp_scope(&laddr->a))

  			continue;

  
  		fl6->saddr = laddr->a.v6.sin6_addr;
  		fl6->fl6_sport = laddr->a.v6.sin6_port;

  		final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);

  		bdst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);

  		if (IS_ERR(bdst))
  			continue;
  
  		if (ipv6_chk_addr(dev_net(bdst->dev),

  				  &laddr->a.v6.sin6_addr, bdst->dev, 1)) {
  			if (!IS_ERR_OR_NULL(dst))
  				dst_release(dst);
  			dst = bdst;
  			break;
  		}
  
  		bmatchlen = sctp_v6_addr_match_len(daddr, &laddr->a);

  		if (matchlen > bmatchlen) {
  			dst_release(bdst);

  			continue;

  		}

  
  		if (!IS_ERR_OR_NULL(dst))
  			dst_release(dst);
  		dst = bdst;
  		matchlen = bmatchlen;

  	}

  	rcu_read_unlock();

  out:

  	if (!IS_ERR_OR_NULL(dst)) {

  		struct rt6_info *rt;

  		rt = (struct rt6_info *)dst;

  		t->dst = dst;

  		t->dst_cookie = rt6_get_cookie(rt);

  		pr_debug("rt6_dst:%pI6/%d rt6_src:%pI6
  ",
  			 &rt->rt6i_dst.addr, rt->rt6i_dst.plen,

  			 &fl6->saddr);

  	} else {
  		t->dst = NULL;

  
  		pr_debug("no route
  ");

  	}

  }
  
  /* Returns the number of consecutive initial bits that match in the 2 ipv6
   * addresses.
   */
  static inline int sctp_v6_addr_match_len(union sctp_addr *s1,
  					 union sctp_addr *s2)
  {

  	return ipv6_addr_diff(&s1->v6.sin6_addr, &s2->v6.sin6_addr);

  }
  
  /* Fills in the source address(saddr) based on the destination address(daddr)
   * and asoc's bind address list.
   */

  static void sctp_v6_get_saddr(struct sctp_sock *sk,

  			      struct sctp_transport *t,

  			      struct flowi *fl)

  {

  	struct flowi6 *fl6 = &fl->u.ip6;
  	union sctp_addr *saddr = &t->saddr;

  	pr_debug("%s: asoc:%p dst:%p
  ", __func__, t->asoc, t->dst);

  	if (t->dst) {
  		saddr->v6.sin6_family = AF_INET6;

  		saddr->v6.sin6_addr = fl6->saddr;

  	}

  }
  
  /* Make a copy of all potential local addresses. */
  static void sctp_v6_copy_addrlist(struct list_head *addrlist,
  				  struct net_device *dev)
  {
  	struct inet6_dev *in6_dev;
  	struct inet6_ifaddr *ifp;
  	struct sctp_sockaddr_entry *addr;

  	rcu_read_lock();

  	if ((in6_dev = __in6_dev_get(dev)) == NULL) {

  		rcu_read_unlock();

  		return;
  	}

  	read_lock_bh(&in6_dev->lock);

  	list_for_each_entry(ifp, &in6_dev->addr_list, if_list) {

  		/* Add the address to the local list.  */

  		addr = kzalloc(sizeof(*addr), GFP_ATOMIC);

  		if (addr) {

  			addr->a.v6.sin6_family = AF_INET6;

  			addr->a.v6.sin6_addr = ifp->addr;

  			addr->a.v6.sin6_scope_id = dev->ifindex;

  			addr->valid = 1;

  			INIT_LIST_HEAD(&addr->list);
  			list_add_tail(&addr->list, addrlist);
  		}
  	}

  	read_unlock_bh(&in6_dev->lock);

  	rcu_read_unlock();

  }

  /* Copy over any ip options */
  static void sctp_v6_copy_ip_options(struct sock *sk, struct sock *newsk)
  {
  	struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
  	struct ipv6_txoptions *opt;
  
  	newnp = inet6_sk(newsk);
  
  	rcu_read_lock();
  	opt = rcu_dereference(np->opt);
  	if (opt) {
  		opt = ipv6_dup_options(newsk, opt);
  		if (!opt)
  			pr_err("%s: Failed to copy ip options
  ", __func__);
  	}
  	RCU_INIT_POINTER(newnp->opt, opt);
  	rcu_read_unlock();
  }
  
  /* Account for the IP options */
  static int sctp_v6_ip_options_len(struct sock *sk)
  {
  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct ipv6_txoptions *opt;
  	int len = 0;
  
  	rcu_read_lock();
  	opt = rcu_dereference(np->opt);
  	if (opt)
  		len = opt->opt_flen + opt->opt_nflen;
  
  	rcu_read_unlock();
  	return len;
  }

  /* Initialize a sockaddr_storage from in incoming skb. */

  static void sctp_v6_from_skb(union sctp_addr *addr, struct sk_buff *skb,

  			     int is_saddr)
  {

  	/* Always called on head skb, so this is safe */
  	struct sctphdr *sh = sctp_hdr(skb);
  	struct sockaddr_in6 *sa = &addr->v6;

  	addr->v6.sin6_family = AF_INET6;
  	addr->v6.sin6_flowinfo = 0; /* FIXME */
  	addr->v6.sin6_scope_id = ((struct inet6_skb_parm *)skb->cb)->iif;

  	if (is_saddr) {

  		sa->sin6_port = sh->source;
  		sa->sin6_addr = ipv6_hdr(skb)->saddr;

  	} else {

  		sa->sin6_port = sh->dest;
  		sa->sin6_addr = ipv6_hdr(skb)->daddr;

  	}

  }
  
  /* Initialize an sctp_addr from a socket. */
  static void sctp_v6_from_sk(union sctp_addr *addr, struct sock *sk)
  {
  	addr->v6.sin6_family = AF_INET6;

  	addr->v6.sin6_port = 0;

  	addr->v6.sin6_addr = sk->sk_v6_rcv_saddr;

  }
  
  /* Initialize sk->sk_rcv_saddr from sctp_addr. */
  static void sctp_v6_to_sk_saddr(union sctp_addr *addr, struct sock *sk)
  {

  	if (addr->sa.sa_family == AF_INET) {

  		sk->sk_v6_rcv_saddr.s6_addr32[0] = 0;
  		sk->sk_v6_rcv_saddr.s6_addr32[1] = 0;
  		sk->sk_v6_rcv_saddr.s6_addr32[2] = htonl(0x0000ffff);
  		sk->sk_v6_rcv_saddr.s6_addr32[3] =

  			addr->v4.sin_addr.s_addr;
  	} else {

  		sk->sk_v6_rcv_saddr = addr->v6.sin6_addr;

  	}
  }
  
  /* Initialize sk->sk_daddr from sctp_addr. */
  static void sctp_v6_to_sk_daddr(union sctp_addr *addr, struct sock *sk)
  {

  	if (addr->sa.sa_family == AF_INET) {

  		sk->sk_v6_daddr.s6_addr32[0] = 0;
  		sk->sk_v6_daddr.s6_addr32[1] = 0;
  		sk->sk_v6_daddr.s6_addr32[2] = htonl(0x0000ffff);
  		sk->sk_v6_daddr.s6_addr32[3] = addr->v4.sin_addr.s_addr;

  	} else {

  		sk->sk_v6_daddr = addr->v6.sin6_addr;

  	}
  }
  
  /* Initialize a sctp_addr from an address parameter. */
  static void sctp_v6_from_addr_param(union sctp_addr *addr,
  				    union sctp_addr_param *param,

  				    __be16 port, int iif)

  {
  	addr->v6.sin6_family = AF_INET6;
  	addr->v6.sin6_port = port;
  	addr->v6.sin6_flowinfo = 0; /* BUG */

  	addr->v6.sin6_addr = param->v6.addr;

  	addr->v6.sin6_scope_id = iif;
  }
  
  /* Initialize an address parameter from a sctp_addr and return the length
   * of the address parameter.
   */
  static int sctp_v6_to_addr_param(const union sctp_addr *addr,
  				 union sctp_addr_param *param)
  {

  	int length = sizeof(struct sctp_ipv6addr_param);

  
  	param->v6.param_hdr.type = SCTP_PARAM_IPV6_ADDRESS;

  	param->v6.param_hdr.length = htons(length);

  	param->v6.addr = addr->v6.sin6_addr;

  
  	return length;
  }

  /* Initialize a sctp_addr from struct in6_addr. */
  static void sctp_v6_to_addr(union sctp_addr *addr, struct in6_addr *saddr,

  			      __be16 port)

  {

  	addr->sa.sa_family = AF_INET6;
  	addr->v6.sin6_port = port;

  	addr->v6.sin6_flowinfo = 0;

  	addr->v6.sin6_addr = *saddr;

  	addr->v6.sin6_scope_id = 0;

  }

  static int __sctp_v6_cmp_addr(const union sctp_addr *addr1,
  			      const union sctp_addr *addr2)

  {
  	if (addr1->sa.sa_family != addr2->sa.sa_family) {
  		if (addr1->sa.sa_family == AF_INET &&
  		    addr2->sa.sa_family == AF_INET6 &&

  		    ipv6_addr_v4mapped(&addr2->v6.sin6_addr) &&
  		    addr2->v6.sin6_addr.s6_addr32[3] ==
  		    addr1->v4.sin_addr.s_addr)
  			return 1;

  		if (addr2->sa.sa_family == AF_INET &&
  		    addr1->sa.sa_family == AF_INET6 &&

  		    ipv6_addr_v4mapped(&addr1->v6.sin6_addr) &&
  		    addr1->v6.sin6_addr.s6_addr32[3] ==
  		    addr2->v4.sin_addr.s_addr)
  			return 1;

  		return 0;
  	}

  	if (!ipv6_addr_equal(&addr1->v6.sin6_addr, &addr2->v6.sin6_addr))
  		return 0;

  	/* If this is a linklocal address, compare the scope_id. */

  	if ((ipv6_addr_type(&addr1->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL) &&
  	    addr1->v6.sin6_scope_id && addr2->v6.sin6_scope_id &&
  	    addr1->v6.sin6_scope_id != addr2->v6.sin6_scope_id)
  		return 0;

  
  	return 1;
  }

  /* Compare addresses exactly.
   * v4-mapped-v6 is also in consideration.
   */
  static int sctp_v6_cmp_addr(const union sctp_addr *addr1,
  			    const union sctp_addr *addr2)
  {
  	return __sctp_v6_cmp_addr(addr1, addr2) &&
  	       addr1->v6.sin6_port == addr2->v6.sin6_port;
  }

  /* Initialize addr struct to INADDR_ANY. */

  static void sctp_v6_inaddr_any(union sctp_addr *addr, __be16 port)

  {
  	memset(addr, 0x00, sizeof(union sctp_addr));
  	addr->v6.sin6_family = AF_INET6;
  	addr->v6.sin6_port = port;
  }
  
  /* Is this a wildcard address? */
  static int sctp_v6_is_any(const union sctp_addr *addr)
  {

  	return ipv6_addr_any(&addr->v6.sin6_addr);

  }
  
  /* Should this be available for binding?   */
  static int sctp_v6_available(union sctp_addr *addr, struct sctp_sock *sp)
  {
  	int type;

  	struct net *net = sock_net(&sp->inet.sk);

  	const struct in6_addr *in6 = (const struct in6_addr *)&addr->v6.sin6_addr;

  
  	type = ipv6_addr_type(in6);
  	if (IPV6_ADDR_ANY == type)
  		return 1;
  	if (type == IPV6_ADDR_MAPPED) {

  		if (sp && ipv6_only_sock(sctp_opt2sk(sp)))
  			return 0;
  		sctp_v6_map_v4(addr);
  		return sctp_get_af_specific(AF_INET)->available(addr, sp);
  	}
  	if (!(type & IPV6_ADDR_UNICAST))
  		return 0;

  	return sp->inet.freebind || net->ipv6.sysctl.ip_nonlocal_bind ||
  		ipv6_chk_addr(net, in6, NULL, 0);

  }
  
  /* This function checks if the address is a valid address to be used for
   * SCTP.
   *
   * Output:
   * Return 0 - If the address is a non-unicast or an illegal address.
   * Return 1 - If the address is a unicast.
   */

  static int sctp_v6_addr_valid(union sctp_addr *addr,
  			      struct sctp_sock *sp,
  			      const struct sk_buff *skb)

  {
  	int ret = ipv6_addr_type(&addr->v6.sin6_addr);
  
  	/* Support v4-mapped-v6 address. */
  	if (ret == IPV6_ADDR_MAPPED) {
  		/* Note: This routine is used in input, so v4-mapped-v6
  		 * are disallowed here when there is no sctp_sock.
  		 */

  		if (sp && ipv6_only_sock(sctp_opt2sk(sp)))
  			return 0;
  		sctp_v6_map_v4(addr);

  		return sctp_get_af_specific(AF_INET)->addr_valid(addr, sp, skb);

  	}
  
  	/* Is this a non-unicast address */
  	if (!(ret & IPV6_ADDR_UNICAST))
  		return 0;
  
  	return 1;
  }
  
  /* What is the scope of 'addr'?  */

  static enum sctp_scope sctp_v6_scope(union sctp_addr *addr)

  {

  	enum sctp_scope retval;

  	int v6scope;

  
  	/* The IPv6 scope is really a set of bit fields.
  	 * See IFA_* in <net/if_inet6.h>.  Map to a generic SCTP scope.
  	 */
  
  	v6scope = ipv6_addr_scope(&addr->v6.sin6_addr);
  	switch (v6scope) {
  	case IFA_HOST:
  		retval = SCTP_SCOPE_LOOPBACK;
  		break;
  	case IFA_LINK:
  		retval = SCTP_SCOPE_LINK;
  		break;
  	case IFA_SITE:
  		retval = SCTP_SCOPE_PRIVATE;
  		break;
  	default:
  		retval = SCTP_SCOPE_GLOBAL;
  		break;

  	}

  
  	return retval;
  }
  
  /* Create and initialize a new sk for the socket to be returned by accept(). */
  static struct sock *sctp_v6_create_accept_sk(struct sock *sk,

  					     struct sctp_association *asoc,
  					     bool kern)

  {

  	struct sock *newsk;

  	struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
  	struct sctp6_sock *newsctp6sk;

  	newsk = sk_alloc(sock_net(sk), PF_INET6, GFP_KERNEL, sk->sk_prot, kern);

  	if (!newsk)
  		goto out;
  
  	sock_init_data(NULL, newsk);

  	sctp_copy_sock(newsk, sk, asoc);

  	sock_reset_flag(sk, SOCK_ZAPPED);
  
  	newsctp6sk = (struct sctp6_sock *)newsk;
  	inet_sk(newsk)->pinet6 = &newsctp6sk->inet6;

  	sctp_sk(newsk)->v4mapped = sctp_sk(sk)->v4mapped;

  	newnp = inet6_sk(newsk);
  
  	memcpy(newnp, np, sizeof(struct ipv6_pinfo));

  	newnp->ipv6_mc_list = NULL;
  	newnp->ipv6_ac_list = NULL;
  	newnp->ipv6_fl_list = NULL;

  	sctp_v6_copy_ip_options(sk, newsk);

  	/* Initialize sk's sport, dport, rcv_saddr and daddr for getsockname()
  	 * and getpeername().
  	 */

  	sctp_v6_to_sk_daddr(&asoc->peer.primary_addr, newsk);

  	newsk->sk_v6_rcv_saddr = sk->sk_v6_rcv_saddr;

  	sk_refcnt_debug_inc(newsk);

  
  	if (newsk->sk_prot->init(newsk)) {
  		sk_common_release(newsk);
  		newsk = NULL;
  	}
  
  out:
  	return newsk;
  }

  /* Format a sockaddr for return to user space. This makes sure the return is
   * AF_INET or AF_INET6 depending on the SCTP_I_WANT_MAPPED_V4_ADDR option.
   */
  static int sctp_v6_addr_to_user(struct sctp_sock *sp, union sctp_addr *addr)

  {

  	if (sp->v4mapped) {
  		if (addr->sa.sa_family == AF_INET)
  			sctp_v4_map_v6(addr);
  	} else {
  		if (addr->sa.sa_family == AF_INET6 &&
  		    ipv6_addr_v4mapped(&addr->v6.sin6_addr))
  			sctp_v6_map_v4(addr);
  	}

  	if (addr->sa.sa_family == AF_INET) {
  		memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));

  		return sizeof(struct sockaddr_in);

  	}

  	return sizeof(struct sockaddr_in6);

  }
  
  /* Where did this skb come from?  */
  static int sctp_v6_skb_iif(const struct sk_buff *skb)
  {

  	return IP6CB(skb)->iif;

  }
  
  /* Was this packet marked by Explicit Congestion Notification? */
  static int sctp_v6_is_ce(const struct sk_buff *skb)
  {

  	return *((__u32 *)(ipv6_hdr(skb))) & (__force __u32)htonl(1 << 20);

  }
  
  /* Dump the v6 addr to the seq file. */
  static void sctp_v6_seq_dump_addr(struct seq_file *seq, union sctp_addr *addr)
  {

  	seq_printf(seq, "%pI6 ", &addr->v6.sin6_addr);

  }

  static void sctp_v6_ecn_capable(struct sock *sk)
  {
  	inet6_sk(sk)->tclass |= INET_ECN_ECT_0;
  }

  /* Initialize a PF_INET msgname from a ulpevent. */
  static void sctp_inet6_event_msgname(struct sctp_ulpevent *event,
  				     char *msgname, int *addrlen)
  {

  	union sctp_addr *addr;
  	struct sctp_association *asoc;
  	union sctp_addr *paddr;

  	if (!msgname)
  		return;

  	addr = (union sctp_addr *)msgname;
  	asoc = event->asoc;
  	paddr = &asoc->peer.primary_addr;

  	if (paddr->sa.sa_family == AF_INET) {
  		addr->v4.sin_family = AF_INET;
  		addr->v4.sin_port = htons(asoc->peer.port);
  		addr->v4.sin_addr = paddr->v4.sin_addr;
  	} else {
  		addr->v6.sin6_family = AF_INET6;
  		addr->v6.sin6_flowinfo = 0;
  		if (ipv6_addr_type(&paddr->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL)
  			addr->v6.sin6_scope_id = paddr->v6.sin6_scope_id;
  		else
  			addr->v6.sin6_scope_id = 0;
  		addr->v6.sin6_port = htons(asoc->peer.port);
  		addr->v6.sin6_addr = paddr->v6.sin6_addr;

  	}

  
  	*addrlen = sctp_v6_addr_to_user(sctp_sk(asoc->base.sk), addr);

  }
  
  /* Initialize a msg_name from an inbound skb. */
  static void sctp_inet6_skb_msgname(struct sk_buff *skb, char *msgname,
  				   int *addr_len)
  {

  	union sctp_addr *addr;

  	struct sctphdr *sh;

  	if (!msgname)
  		return;
  
  	addr = (union sctp_addr *)msgname;
  	sh = sctp_hdr(skb);
  
  	if (ip_hdr(skb)->version == 4) {
  		addr->v4.sin_family = AF_INET;
  		addr->v4.sin_port = sh->source;

  		addr->v4.sin_addr.s_addr = ip_hdr(skb)->saddr;

  	} else {
  		addr->v6.sin6_family = AF_INET6;
  		addr->v6.sin6_flowinfo = 0;
  		addr->v6.sin6_port = sh->source;
  		addr->v6.sin6_addr = ipv6_hdr(skb)->saddr;

  		if (ipv6_addr_type(&addr->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL)

  			addr->v6.sin6_scope_id = sctp_v6_skb_iif(skb);

  		else
  			addr->v6.sin6_scope_id = 0;

  	}

  
  	*addr_len = sctp_v6_addr_to_user(sctp_sk(skb->sk), addr);

  }
  
  /* Do we support this AF? */
  static int sctp_inet6_af_supported(sa_family_t family, struct sctp_sock *sp)
  {
  	switch (family) {
  	case AF_INET6:
  		return 1;
  	/* v4-mapped-v6 addresses */
  	case AF_INET:

  		if (!__ipv6_only_sock(sctp_opt2sk(sp)))

  			return 1;

  		/* fallthru */

  	default:
  		return 0;
  	}
  }
  
  /* Address matching with wildcards allowed.  This extra level
   * of indirection lets us choose whether a PF_INET6 should
   * disallow any v4 addresses if we so choose.
   */
  static int sctp_inet6_cmp_addr(const union sctp_addr *addr1,
  			       const union sctp_addr *addr2,
  			       struct sctp_sock *opt)
  {

  	struct sock *sk = sctp_opt2sk(opt);

  	struct sctp_af *af1, *af2;

  
  	af1 = sctp_get_af_specific(addr1->sa.sa_family);
  	af2 = sctp_get_af_specific(addr2->sa.sa_family);
  
  	if (!af1 || !af2)
  		return 0;

  
  	/* If the socket is IPv6 only, v4 addrs will not match */

  	if (__ipv6_only_sock(sk) && af1 != af2)

  		return 0;

  	/* Today, wildcard AF_INET/AF_INET6. */

  	if (sctp_is_any(sk, addr1) || sctp_is_any(sk, addr2))

  		return 1;

  	if (addr1->sa.sa_family == AF_INET && addr2->sa.sa_family == AF_INET)
  		return addr1->v4.sin_addr.s_addr == addr2->v4.sin_addr.s_addr;

  	return __sctp_v6_cmp_addr(addr1, addr2);

  }
  
  /* Verify that the provided sockaddr looks bindable.   Common verification,
   * has already been taken care of.
   */
  static int sctp_inet6_bind_verify(struct sctp_sock *opt, union sctp_addr *addr)
  {
  	struct sctp_af *af;
  
  	/* ASSERT: address family has already been verified. */
  	if (addr->sa.sa_family != AF_INET6)
  		af = sctp_get_af_specific(addr->sa.sa_family);
  	else {

  		int type = ipv6_addr_type(&addr->v6.sin6_addr);

  		struct net_device *dev;

  		if (type & IPV6_ADDR_LINKLOCAL) {

  			struct net *net;

  			if (!addr->v6.sin6_scope_id)
  				return 0;

  			net = sock_net(&opt->inet.sk);

  			rcu_read_lock();

  			dev = dev_get_by_index_rcu(net, addr->v6.sin6_scope_id);

  			if (!dev || !(opt->inet.freebind ||
  				      net->ipv6.sysctl.ip_nonlocal_bind ||
  				      ipv6_chk_addr(net, &addr->v6.sin6_addr,
  						    dev, 0))) {

  				rcu_read_unlock();

  				return 0;
  			}

  			rcu_read_unlock();

  		}

  		af = opt->pf->af;
  	}
  	return af->available(addr, opt);
  }

  /* Verify that the provided sockaddr looks sendable.   Common verification,

   * has already been taken care of.
   */
  static int sctp_inet6_send_verify(struct sctp_sock *opt, union sctp_addr *addr)
  {
  	struct sctp_af *af = NULL;
  
  	/* ASSERT: address family has already been verified. */
  	if (addr->sa.sa_family != AF_INET6)
  		af = sctp_get_af_specific(addr->sa.sa_family);
  	else {

  		int type = ipv6_addr_type(&addr->v6.sin6_addr);

  		struct net_device *dev;

  		if (type & IPV6_ADDR_LINKLOCAL) {

  			if (!addr->v6.sin6_scope_id)
  				return 0;

  			rcu_read_lock();

  			dev = dev_get_by_index_rcu(sock_net(&opt->inet.sk),

  						   addr->v6.sin6_scope_id);
  			rcu_read_unlock();

  			if (!dev)

  				return 0;
  		}
  		af = opt->pf->af;
  	}
  
  	return af != NULL;
  }
  
  /* Fill in Supported Address Type information for INIT and INIT-ACK
   * chunks.   Note: In the future, we may want to look at sock options
   * to determine whether a PF_INET6 socket really wants to have IPV4
   * addresses.
   * Returns number of addresses supported.
   */
  static int sctp_inet6_supported_addrs(const struct sctp_sock *opt,

  				      __be16 *types)

  {

  	types[0] = SCTP_PARAM_IPV6_ADDRESS;
  	if (!opt || !ipv6_only_sock(sctp_opt2sk(opt))) {
  		types[1] = SCTP_PARAM_IPV4_ADDRESS;
  		return 2;
  	}
  	return 1;

  }

  /* Handle SCTP_I_WANT_MAPPED_V4_ADDR for getpeername() and getsockname() */
  static int sctp_getname(struct socket *sock, struct sockaddr *uaddr,

  			int peer)

  {
  	int rc;

  	rc = inet6_getname(sock, uaddr, peer);

  	if (rc < 0)

  		return rc;

  	rc = sctp_v6_addr_to_user(sctp_sk(sock->sk),

  					  (union sctp_addr *)uaddr);
  
  	return rc;
  }

  static const struct proto_ops inet6_seqpacket_ops = {

  	.family		   = PF_INET6,
  	.owner		   = THIS_MODULE,
  	.release	   = inet6_release,
  	.bind		   = inet6_bind,

  	.connect	   = sctp_inet_connect,

  	.socketpair	   = sock_no_socketpair,
  	.accept		   = inet_accept,

  	.getname	   = sctp_getname,

  	.poll		   = sctp_poll,

  	.ioctl		   = inet6_ioctl,

  	.gettstamp	   = sock_gettstamp,

  	.listen		   = sctp_inet_listen,
  	.shutdown	   = inet_shutdown,
  	.setsockopt	   = sock_common_setsockopt,
  	.getsockopt	   = sock_common_getsockopt,
  	.sendmsg	   = inet_sendmsg,

  	.recvmsg	   = inet_recvmsg,

  	.mmap		   = sock_no_mmap,

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_sock_common_setsockopt,
  	.compat_getsockopt = compat_sock_common_getsockopt,

  #endif

  };
  
  static struct inet_protosw sctpv6_seqpacket_protosw = {
  	.type          = SOCK_SEQPACKET,
  	.protocol      = IPPROTO_SCTP,
  	.prot 	       = &sctpv6_prot,
  	.ops           = &inet6_seqpacket_ops,

  	.flags         = SCTP_PROTOSW_FLAG
  };
  static struct inet_protosw sctpv6_stream_protosw = {
  	.type          = SOCK_STREAM,
  	.protocol      = IPPROTO_SCTP,
  	.prot 	       = &sctpv6_prot,
  	.ops           = &inet6_seqpacket_ops,

  	.flags         = SCTP_PROTOSW_FLAG,
  };

  static int sctp6_rcv(struct sk_buff *skb)

  {

  	return sctp_rcv(skb) ? -1 : 0;

  }

  static const struct inet6_protocol sctpv6_protocol = {

  	.handler      = sctp6_rcv,
  	.err_handler  = sctp_v6_err,
  	.flags        = INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,
  };

  static struct sctp_af sctp_af_inet6 = {

  	.sa_family	   = AF_INET6,
  	.sctp_xmit	   = sctp_v6_xmit,
  	.setsockopt	   = ipv6_setsockopt,
  	.getsockopt	   = ipv6_getsockopt,
  	.get_dst	   = sctp_v6_get_dst,
  	.get_saddr	   = sctp_v6_get_saddr,
  	.copy_addrlist	   = sctp_v6_copy_addrlist,
  	.from_skb	   = sctp_v6_from_skb,
  	.from_sk	   = sctp_v6_from_sk,

  	.from_addr_param   = sctp_v6_from_addr_param,
  	.to_addr_param	   = sctp_v6_to_addr_param,

  	.cmp_addr	   = sctp_v6_cmp_addr,
  	.scope		   = sctp_v6_scope,
  	.addr_valid	   = sctp_v6_addr_valid,
  	.inaddr_any	   = sctp_v6_inaddr_any,
  	.is_any		   = sctp_v6_is_any,
  	.available	   = sctp_v6_available,
  	.skb_iif	   = sctp_v6_skb_iif,
  	.is_ce		   = sctp_v6_is_ce,
  	.seq_dump_addr	   = sctp_v6_seq_dump_addr,

  	.ecn_capable	   = sctp_v6_ecn_capable,

  	.net_header_len	   = sizeof(struct ipv6hdr),
  	.sockaddr_len	   = sizeof(struct sockaddr_in6),

  	.ip_options_len	   = sctp_v6_ip_options_len,

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_ipv6_setsockopt,
  	.compat_getsockopt = compat_ipv6_getsockopt,

  #endif

  };

  static struct sctp_pf sctp_pf_inet6 = {

  	.event_msgname = sctp_inet6_event_msgname,
  	.skb_msgname   = sctp_inet6_skb_msgname,
  	.af_supported  = sctp_inet6_af_supported,
  	.cmp_addr      = sctp_inet6_cmp_addr,
  	.bind_verify   = sctp_inet6_bind_verify,
  	.send_verify   = sctp_inet6_send_verify,
  	.supported_addrs = sctp_inet6_supported_addrs,
  	.create_accept_sk = sctp_v6_create_accept_sk,

  	.addr_to_user  = sctp_v6_addr_to_user,
  	.to_sk_saddr   = sctp_v6_to_sk_saddr,
  	.to_sk_daddr   = sctp_v6_to_sk_daddr,

  	.copy_ip_options = sctp_v6_copy_ip_options,

  	.af            = &sctp_af_inet6,

  };

  /* Initialize IPv6 support and register with socket layer.  */

  void sctp_v6_pf_init(void)

  {

  	/* Register the SCTP specific PF_INET6 functions. */

  	sctp_register_pf(&sctp_pf_inet6, PF_INET6);

  
  	/* Register the SCTP specific AF_INET6 functions. */

  	sctp_register_af(&sctp_af_inet6);

  }
  
  void sctp_v6_pf_exit(void)
  {
  	list_del(&sctp_af_inet6.list);
  }
  
  /* Initialize IPv6 support and register with socket layer.  */
  int sctp_v6_protosw_init(void)
  {
  	int rc;

  
  	rc = proto_register(&sctpv6_prot, 1);

  	if (rc)

  		return rc;

  
  	/* Add SCTPv6(UDP and TCP style) to inetsw6 linked list. */
  	inet6_register_protosw(&sctpv6_seqpacket_protosw);
  	inet6_register_protosw(&sctpv6_stream_protosw);

  	return 0;
  }

  void sctp_v6_protosw_exit(void)
  {
  	inet6_unregister_protosw(&sctpv6_seqpacket_protosw);
  	inet6_unregister_protosw(&sctpv6_stream_protosw);
  	proto_unregister(&sctpv6_prot);
  }

  /* Register with inet6 layer. */
  int sctp_v6_add_protocol(void)
  {

  	/* Register notifier for inet6 address additions/deletions. */
  	register_inet6addr_notifier(&sctp_inet6addr_notifier);

  
  	if (inet6_add_protocol(&sctpv6_protocol, IPPROTO_SCTP) < 0)
  		return -EAGAIN;
  
  	return 0;

  }

  /* Unregister with inet6 layer. */
  void sctp_v6_del_protocol(void)
  {
  	inet6_del_protocol(&sctpv6_protocol, IPPROTO_SCTP);
  	unregister_inet6addr_notifier(&sctp_inet6addr_notifier);

  }