/*
   * IPv6 Address Label subsystem
   * for the IPv6 "Default" Source Address Selection
   *
   * Copyright (C)2007 USAGI/WIDE Project
   */
  /*
   * Author:
   * 	YOSHIFUJI Hideaki @ USAGI/WIDE Project <yoshfuji@linux-ipv6.org>
   */
  
  #include <linux/kernel.h>
  #include <linux/list.h>
  #include <linux/rcupdate.h>
  #include <linux/in6.h>

  #include <linux/slab.h>

  #include <net/addrconf.h>
  #include <linux/if_addrlabel.h>
  #include <linux/netlink.h>
  #include <linux/rtnetlink.h>
  
  #if 0
  #define ADDRLABEL(x...) printk(x)
  #else
  #define ADDRLABEL(x...) do { ; } while(0)
  #endif
  
  /*
   * Policy Table
   */
  struct ip6addrlbl_entry
  {

  #ifdef CONFIG_NET_NS
  	struct net *lbl_net;
  #endif

  	struct in6_addr prefix;
  	int prefixlen;
  	int ifindex;
  	int addrtype;
  	u32 label;
  	struct hlist_node list;
  	atomic_t refcnt;
  	struct rcu_head rcu;
  };
  
  static struct ip6addrlbl_table
  {
  	struct hlist_head head;
  	spinlock_t lock;
  	u32 seq;
  } ip6addrlbl_table;

  static inline
  struct net *ip6addrlbl_net(const struct ip6addrlbl_entry *lbl)
  {

  	return read_pnet(&lbl->lbl_net);

  }

  /*
   * Default policy table (RFC3484 + extensions)
   *
   * prefix		addr_type	label
   * -------------------------------------------------------------------------
   * ::1/128		LOOPBACK	0
   * ::/0			N/A		1
   * 2002::/16		N/A		2
   * ::/96		COMPATv4	3
   * ::ffff:0:0/96	V4MAPPED	4
   * fc00::/7		N/A		5		ULA (RFC 4193)
   * 2001::/32		N/A		6		Teredo (RFC 4380)

   * 2001:10::/28		N/A		7		ORCHID (RFC 4843)

   *
   * Note: 0xffffffff is used if we do not have any policies.
   */
  
  #define IPV6_ADDR_LABEL_DEFAULT	0xffffffffUL

  static const __net_initdata struct ip6addrlbl_init_table

  {
  	const struct in6_addr *prefix;
  	int prefixlen;
  	u32 label;
  } ip6addrlbl_init_table[] = {
  	{	/* ::/0 */
  		.prefix = &in6addr_any,
  		.label = 1,
  	},{	/* fc00::/7 */
  		.prefix = &(struct in6_addr){{{ 0xfc }}},
  		.prefixlen = 7,
  		.label = 5,
  	},{	/* 2002::/16 */
  		.prefix = &(struct in6_addr){{{ 0x20, 0x02 }}},
  		.prefixlen = 16,
  		.label = 2,
  	},{	/* 2001::/32 */
  		.prefix = &(struct in6_addr){{{ 0x20, 0x01 }}},
  		.prefixlen = 32,
  		.label = 6,

  	},{	/* 2001:10::/28 */
  		.prefix = &(struct in6_addr){{{ 0x20, 0x01, 0x00, 0x10 }}},
  		.prefixlen = 28,
  		.label = 7,

  	},{	/* ::ffff:0:0 */
  		.prefix = &(struct in6_addr){{{ [10] = 0xff, [11] = 0xff }}},
  		.prefixlen = 96,
  		.label = 4,
  	},{	/* ::/96 */
  		.prefix = &in6addr_any,
  		.prefixlen = 96,
  		.label = 3,
  	},{	/* ::1/128 */
  		.prefix = &in6addr_loopback,
  		.prefixlen = 128,
  		.label = 0,
  	}
  };
  
  /* Object management */
  static inline void ip6addrlbl_free(struct ip6addrlbl_entry *p)
  {

  #ifdef CONFIG_NET_NS
  	release_net(p->lbl_net);
  #endif

  	kfree(p);
  }

  static void ip6addrlbl_free_rcu(struct rcu_head *h)
  {
  	ip6addrlbl_free(container_of(h, struct ip6addrlbl_entry, rcu));
  }

  static inline int ip6addrlbl_hold(struct ip6addrlbl_entry *p)
  {
  	return atomic_inc_not_zero(&p->refcnt);
  }
  
  static inline void ip6addrlbl_put(struct ip6addrlbl_entry *p)
  {
  	if (atomic_dec_and_test(&p->refcnt))

  		call_rcu(&p->rcu, ip6addrlbl_free_rcu);

  }
  
  /* Find label */

  static int __ip6addrlbl_match(struct net *net,
  			      struct ip6addrlbl_entry *p,

  			      const struct in6_addr *addr,
  			      int addrtype, int ifindex)
  {

  	if (!net_eq(ip6addrlbl_net(p), net))
  		return 0;

  	if (p->ifindex && p->ifindex != ifindex)
  		return 0;
  	if (p->addrtype && p->addrtype != addrtype)
  		return 0;
  	if (!ipv6_prefix_equal(addr, &p->prefix, p->prefixlen))
  		return 0;
  	return 1;
  }

  static struct ip6addrlbl_entry *__ipv6_addr_label(struct net *net,
  						  const struct in6_addr *addr,

  						  int type, int ifindex)
  {
  	struct hlist_node *pos;
  	struct ip6addrlbl_entry *p;
  	hlist_for_each_entry_rcu(p, pos, &ip6addrlbl_table.head, list) {

  		if (__ip6addrlbl_match(net, p, addr, type, ifindex))

  			return p;
  	}
  	return NULL;
  }

  u32 ipv6_addr_label(struct net *net,
  		    const struct in6_addr *addr, int type, int ifindex)

  {
  	u32 label;
  	struct ip6addrlbl_entry *p;
  
  	type &= IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK;
  
  	rcu_read_lock();

  	p = __ipv6_addr_label(net, addr, type, ifindex);

  	label = p ? p->label : IPV6_ADDR_LABEL_DEFAULT;
  	rcu_read_unlock();

  	ADDRLABEL(KERN_DEBUG "%s(addr=%pI6, type=%d, ifindex=%d) => %08x
  ",

  		  __func__, addr, type, ifindex, label);

  
  	return label;
  }
  
  /* allocate one entry */

  static struct ip6addrlbl_entry *ip6addrlbl_alloc(struct net *net,
  						 const struct in6_addr *prefix,

  						 int prefixlen, int ifindex,
  						 u32 label)

  {
  	struct ip6addrlbl_entry *newp;
  	int addrtype;

  	ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u)
  ",

  		  __func__, prefix, prefixlen, ifindex, (unsigned int)label);

  
  	addrtype = ipv6_addr_type(prefix) & (IPV6_ADDR_MAPPED | IPV6_ADDR_COMPATv4 | IPV6_ADDR_LOOPBACK);
  
  	switch (addrtype) {
  	case IPV6_ADDR_MAPPED:
  		if (prefixlen > 96)
  			return ERR_PTR(-EINVAL);
  		if (prefixlen < 96)
  			addrtype = 0;
  		break;
  	case IPV6_ADDR_COMPATv4:
  		if (prefixlen != 96)
  			addrtype = 0;
  		break;
  	case IPV6_ADDR_LOOPBACK:
  		if (prefixlen != 128)
  			addrtype = 0;
  		break;
  	}
  
  	newp = kmalloc(sizeof(*newp), GFP_KERNEL);
  	if (!newp)
  		return ERR_PTR(-ENOMEM);
  
  	ipv6_addr_prefix(&newp->prefix, prefix, prefixlen);
  	newp->prefixlen = prefixlen;
  	newp->ifindex = ifindex;
  	newp->addrtype = addrtype;
  	newp->label = label;
  	INIT_HLIST_NODE(&newp->list);

  #ifdef CONFIG_NET_NS
  	newp->lbl_net = hold_net(net);
  #endif

  	atomic_set(&newp->refcnt, 1);
  	return newp;
  }
  
  /* add a label */

  static int __ip6addrlbl_add(struct ip6addrlbl_entry *newp, int replace)

  {
  	int ret = 0;
  
  	ADDRLABEL(KERN_DEBUG "%s(newp=%p, replace=%d)
  ",

  			__func__,

  			newp, replace);
  
  	if (hlist_empty(&ip6addrlbl_table.head)) {
  		hlist_add_head_rcu(&newp->list, &ip6addrlbl_table.head);
  	} else {
  		struct hlist_node *pos, *n;
  		struct ip6addrlbl_entry *p = NULL;
  		hlist_for_each_entry_safe(p, pos, n,
  					  &ip6addrlbl_table.head, list) {
  			if (p->prefixlen == newp->prefixlen &&

  			    net_eq(ip6addrlbl_net(p), ip6addrlbl_net(newp)) &&

  			    p->ifindex == newp->ifindex &&
  			    ipv6_addr_equal(&p->prefix, &newp->prefix)) {
  				if (!replace) {
  					ret = -EEXIST;
  					goto out;
  				}
  				hlist_replace_rcu(&p->list, &newp->list);
  				ip6addrlbl_put(p);

  				goto out;
  			} else if ((p->prefixlen == newp->prefixlen && !p->ifindex) ||
  				   (p->prefixlen < newp->prefixlen)) {
  				hlist_add_before_rcu(&newp->list, &p->list);
  				goto out;
  			}
  		}
  		hlist_add_after_rcu(&p->list, &newp->list);
  	}
  out:
  	if (!ret)
  		ip6addrlbl_table.seq++;
  	return ret;
  }
  
  /* add a label */

  static int ip6addrlbl_add(struct net *net,
  			  const struct in6_addr *prefix, int prefixlen,

  			  int ifindex, u32 label, int replace)

  {
  	struct ip6addrlbl_entry *newp;
  	int ret = 0;

  	ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d, label=%u, replace=%d)
  ",

  		  __func__, prefix, prefixlen, ifindex, (unsigned int)label,
  		  replace);

  	newp = ip6addrlbl_alloc(net, prefix, prefixlen, ifindex, label);

  	if (IS_ERR(newp))
  		return PTR_ERR(newp);
  	spin_lock(&ip6addrlbl_table.lock);
  	ret = __ip6addrlbl_add(newp, replace);
  	spin_unlock(&ip6addrlbl_table.lock);
  	if (ret)
  		ip6addrlbl_free(newp);
  	return ret;
  }
  
  /* remove a label */

  static int __ip6addrlbl_del(struct net *net,
  			    const struct in6_addr *prefix, int prefixlen,

  			    int ifindex)

  {
  	struct ip6addrlbl_entry *p = NULL;
  	struct hlist_node *pos, *n;
  	int ret = -ESRCH;

  	ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)
  ",

  		  __func__, prefix, prefixlen, ifindex);

  
  	hlist_for_each_entry_safe(p, pos, n, &ip6addrlbl_table.head, list) {
  		if (p->prefixlen == prefixlen &&

  		    net_eq(ip6addrlbl_net(p), net) &&

  		    p->ifindex == ifindex &&
  		    ipv6_addr_equal(&p->prefix, prefix)) {
  			hlist_del_rcu(&p->list);
  			ip6addrlbl_put(p);

  			ret = 0;
  			break;
  		}
  	}
  	return ret;
  }

  static int ip6addrlbl_del(struct net *net,
  			  const struct in6_addr *prefix, int prefixlen,

  			  int ifindex)

  {
  	struct in6_addr prefix_buf;
  	int ret;

  	ADDRLABEL(KERN_DEBUG "%s(prefix=%pI6, prefixlen=%d, ifindex=%d)
  ",

  		  __func__, prefix, prefixlen, ifindex);

  
  	ipv6_addr_prefix(&prefix_buf, prefix, prefixlen);
  	spin_lock(&ip6addrlbl_table.lock);

  	ret = __ip6addrlbl_del(net, &prefix_buf, prefixlen, ifindex);

  	spin_unlock(&ip6addrlbl_table.lock);
  	return ret;
  }
  
  /* add default label */

  static int __net_init ip6addrlbl_net_init(struct net *net)

  {
  	int err = 0;
  	int i;

  	ADDRLABEL(KERN_DEBUG "%s()
  ", __func__);

  
  	for (i = 0; i < ARRAY_SIZE(ip6addrlbl_init_table); i++) {

  		int ret = ip6addrlbl_add(net,
  					 ip6addrlbl_init_table[i].prefix,

  					 ip6addrlbl_init_table[i].prefixlen,
  					 0,
  					 ip6addrlbl_init_table[i].label, 0);
  		/* XXX: should we free all rules when we catch an error? */
  		if (ret && (!err || err != -ENOMEM))
  			err = ret;
  	}
  	return err;
  }

  static void __net_exit ip6addrlbl_net_exit(struct net *net)
  {
  	struct ip6addrlbl_entry *p = NULL;
  	struct hlist_node *pos, *n;
  
  	/* Remove all labels belonging to the exiting net */
  	spin_lock(&ip6addrlbl_table.lock);
  	hlist_for_each_entry_safe(p, pos, n, &ip6addrlbl_table.head, list) {
  		if (net_eq(ip6addrlbl_net(p), net)) {
  			hlist_del_rcu(&p->list);
  			ip6addrlbl_put(p);
  		}
  	}
  	spin_unlock(&ip6addrlbl_table.lock);
  }
  
  static struct pernet_operations ipv6_addr_label_ops = {
  	.init = ip6addrlbl_net_init,
  	.exit = ip6addrlbl_net_exit,
  };

  int __init ipv6_addr_label_init(void)
  {
  	spin_lock_init(&ip6addrlbl_table.lock);

  	return register_pernet_subsys(&ipv6_addr_label_ops);

  }

  void ipv6_addr_label_cleanup(void)
  {
  	unregister_pernet_subsys(&ipv6_addr_label_ops);
  }

  static const struct nla_policy ifal_policy[IFAL_MAX+1] = {
  	[IFAL_ADDRESS]		= { .len = sizeof(struct in6_addr), },
  	[IFAL_LABEL]		= { .len = sizeof(u32), },
  };
  
  static int ip6addrlbl_newdel(struct sk_buff *skb, struct nlmsghdr *nlh,
  			     void *arg)
  {

  	struct net *net = sock_net(skb->sk);

  	struct ifaddrlblmsg *ifal;
  	struct nlattr *tb[IFAL_MAX+1];
  	struct in6_addr *pfx;
  	u32 label;
  	int err = 0;
  
  	err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy);
  	if (err < 0)
  		return err;
  
  	ifal = nlmsg_data(nlh);
  
  	if (ifal->ifal_family != AF_INET6 ||
  	    ifal->ifal_prefixlen > 128)
  		return -EINVAL;

  	if (!tb[IFAL_ADDRESS])
  		return -EINVAL;
  
  	pfx = nla_data(tb[IFAL_ADDRESS]);
  	if (!pfx)
  		return -EINVAL;
  
  	if (!tb[IFAL_LABEL])
  		return -EINVAL;
  	label = nla_get_u32(tb[IFAL_LABEL]);
  	if (label == IPV6_ADDR_LABEL_DEFAULT)
  		return -EINVAL;
  
  	switch(nlh->nlmsg_type) {
  	case RTM_NEWADDRLABEL:

  		if (ifal->ifal_index &&
  		    !__dev_get_by_index(net, ifal->ifal_index))
  			return -EINVAL;

  		err = ip6addrlbl_add(net, pfx, ifal->ifal_prefixlen,

  				     ifal->ifal_index, label,
  				     nlh->nlmsg_flags & NLM_F_REPLACE);
  		break;
  	case RTM_DELADDRLABEL:

  		err = ip6addrlbl_del(net, pfx, ifal->ifal_prefixlen,

  				     ifal->ifal_index);
  		break;
  	default:
  		err = -EOPNOTSUPP;
  	}
  	return err;
  }
  
  static inline void ip6addrlbl_putmsg(struct nlmsghdr *nlh,
  				     int prefixlen, int ifindex, u32 lseq)
  {
  	struct ifaddrlblmsg *ifal = nlmsg_data(nlh);
  	ifal->ifal_family = AF_INET6;
  	ifal->ifal_prefixlen = prefixlen;
  	ifal->ifal_flags = 0;
  	ifal->ifal_index = ifindex;
  	ifal->ifal_seq = lseq;
  };
  
  static int ip6addrlbl_fill(struct sk_buff *skb,
  			   struct ip6addrlbl_entry *p,
  			   u32 lseq,
  			   u32 pid, u32 seq, int event,
  			   unsigned int flags)
  {
  	struct nlmsghdr *nlh = nlmsg_put(skb, pid, seq, event,
  					 sizeof(struct ifaddrlblmsg), flags);
  	if (!nlh)
  		return -EMSGSIZE;
  
  	ip6addrlbl_putmsg(nlh, p->prefixlen, p->ifindex, lseq);
  
  	if (nla_put(skb, IFAL_ADDRESS, 16, &p->prefix) < 0 ||
  	    nla_put_u32(skb, IFAL_LABEL, p->label) < 0) {
  		nlmsg_cancel(skb, nlh);
  		return -EMSGSIZE;
  	}
  
  	return nlmsg_end(skb, nlh);
  }
  
  static int ip6addrlbl_dump(struct sk_buff *skb, struct netlink_callback *cb)
  {

  	struct net *net = sock_net(skb->sk);

  	struct ip6addrlbl_entry *p;
  	struct hlist_node *pos;
  	int idx = 0, s_idx = cb->args[0];
  	int err;
  
  	rcu_read_lock();
  	hlist_for_each_entry_rcu(p, pos, &ip6addrlbl_table.head, list) {

  		if (idx >= s_idx &&
  		    net_eq(ip6addrlbl_net(p), net)) {

  			if ((err = ip6addrlbl_fill(skb, p,
  						   ip6addrlbl_table.seq,
  						   NETLINK_CB(cb->skb).pid,
  						   cb->nlh->nlmsg_seq,
  						   RTM_NEWADDRLABEL,
  						   NLM_F_MULTI)) <= 0)
  				break;
  		}
  		idx++;
  	}
  	rcu_read_unlock();
  	cb->args[0] = idx;
  	return skb->len;
  }
  
  static inline int ip6addrlbl_msgsize(void)
  {

  	return NLMSG_ALIGN(sizeof(struct ifaddrlblmsg))

  		+ nla_total_size(16)	/* IFAL_ADDRESS */

  		+ nla_total_size(4);	/* IFAL_LABEL */

  }
  
  static int ip6addrlbl_get(struct sk_buff *in_skb, struct nlmsghdr* nlh,
  			  void *arg)
  {

  	struct net *net = sock_net(in_skb->sk);

  	struct ifaddrlblmsg *ifal;
  	struct nlattr *tb[IFAL_MAX+1];
  	struct in6_addr *addr;
  	u32 lseq;
  	int err = 0;
  	struct ip6addrlbl_entry *p;
  	struct sk_buff *skb;
  
  	err = nlmsg_parse(nlh, sizeof(*ifal), tb, IFAL_MAX, ifal_policy);
  	if (err < 0)
  		return err;
  
  	ifal = nlmsg_data(nlh);
  
  	if (ifal->ifal_family != AF_INET6 ||
  	    ifal->ifal_prefixlen != 128)
  		return -EINVAL;
  
  	if (ifal->ifal_index &&

  	    !__dev_get_by_index(net, ifal->ifal_index))

  		return -EINVAL;
  
  	if (!tb[IFAL_ADDRESS])
  		return -EINVAL;
  
  	addr = nla_data(tb[IFAL_ADDRESS]);
  	if (!addr)
  		return -EINVAL;
  
  	rcu_read_lock();

  	p = __ipv6_addr_label(net, addr, ipv6_addr_type(addr), ifal->ifal_index);

  	if (p && ip6addrlbl_hold(p))
  		p = NULL;
  	lseq = ip6addrlbl_table.seq;
  	rcu_read_unlock();
  
  	if (!p) {
  		err = -ESRCH;
  		goto out;
  	}
  
  	if (!(skb = nlmsg_new(ip6addrlbl_msgsize(), GFP_KERNEL))) {
  		ip6addrlbl_put(p);
  		return -ENOBUFS;
  	}
  
  	err = ip6addrlbl_fill(skb, p, lseq,
  			      NETLINK_CB(in_skb).pid, nlh->nlmsg_seq,
  			      RTM_NEWADDRLABEL, 0);
  
  	ip6addrlbl_put(p);
  
  	if (err < 0) {
  		WARN_ON(err == -EMSGSIZE);
  		kfree_skb(skb);
  		goto out;
  	}

  	err = rtnl_unicast(skb, net, NETLINK_CB(in_skb).pid);

  out:
  	return err;
  }
  
  void __init ipv6_addr_label_rtnl_register(void)
  {

  	__rtnl_register(PF_INET6, RTM_NEWADDRLABEL, ip6addrlbl_newdel,
  			NULL, NULL);
  	__rtnl_register(PF_INET6, RTM_DELADDRLABEL, ip6addrlbl_newdel,
  			NULL, NULL);
  	__rtnl_register(PF_INET6, RTM_GETADDRLABEL, ip6addrlbl_get,
  			ip6addrlbl_dump, NULL);

  }