text: /*
   * lwtunnel	Infrastructure for light weight tunnels like mpls
   *
   * Authors:	Roopa Prabhu, <roopa@cumulusnetworks.com>
   *
   *		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/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/uaccess.h>
  #include <linux/skbuff.h>
  #include <linux/netdevice.h>
  #include <linux/lwtunnel.h>
  #include <linux/in.h>
  #include <linux/init.h>
  #include <linux/err.h>
  
  #include <net/lwtunnel.h>
  #include <net/rtnetlink.h>
  #include <net/ip6_fib.h>
  
  #ifdef CONFIG_MODULES
  
  static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
  {
  	/* Only lwt encaps implemented without using an interface for
  	 * the encap need to return a string here.
  	 */
  	switch (encap_type) {
  	case LWTUNNEL_ENCAP_MPLS:
  		return "MPLS";
  	case LWTUNNEL_ENCAP_ILA:
  		return "ILA";
  	case LWTUNNEL_ENCAP_IP6:
  	case LWTUNNEL_ENCAP_IP:
  	case LWTUNNEL_ENCAP_NONE:
  	case __LWTUNNEL_ENCAP_MAX:
  		/* should not have got here */
  		WARN_ON(1);
  		break;
  	}
  	return NULL;
  }
  
  #endif /* CONFIG_MODULES */
  
  struct lwtunnel_state *lwtunnel_state_alloc(int encap_len)
  {
  	struct lwtunnel_state *lws;
  
  	lws = kzalloc(sizeof(*lws) + encap_len, GFP_ATOMIC);
  
  	return lws;
  }
  EXPORT_SYMBOL(lwtunnel_state_alloc);
  
  static const struct lwtunnel_encap_ops __rcu *
  		lwtun_encaps[LWTUNNEL_ENCAP_MAX + 1] __read_mostly;
  
  int lwtunnel_encap_add_ops(const struct lwtunnel_encap_ops *ops,
  			   unsigned int num)
  {
  	if (num > LWTUNNEL_ENCAP_MAX)
  		return -ERANGE;
  
  	return !cmpxchg((const struct lwtunnel_encap_ops **)
  			&lwtun_encaps[num],
  			NULL, ops) ? 0 : -1;
  }
  EXPORT_SYMBOL(lwtunnel_encap_add_ops);
  
  int lwtunnel_encap_del_ops(const struct lwtunnel_encap_ops *ops,
  			   unsigned int encap_type)
  {
  	int ret;
  
  	if (encap_type == LWTUNNEL_ENCAP_NONE ||
  	    encap_type > LWTUNNEL_ENCAP_MAX)
  		return -ERANGE;
  
  	ret = (cmpxchg((const struct lwtunnel_encap_ops **)
  		       &lwtun_encaps[encap_type],
  		       ops, NULL) == ops) ? 0 : -1;
  
  	synchronize_net();
  
  	return ret;
  }
  EXPORT_SYMBOL(lwtunnel_encap_del_ops);
  
  int lwtunnel_build_state(struct net_device *dev, u16 encap_type,
  			 struct nlattr *encap, unsigned int family,
  			 const void *cfg, struct lwtunnel_state **lws)
  {
  	const struct lwtunnel_encap_ops *ops;
  	int ret = -EINVAL;
  
  	if (encap_type == LWTUNNEL_ENCAP_NONE ||
  	    encap_type > LWTUNNEL_ENCAP_MAX)
  		return ret;
  
  	ret = -EOPNOTSUPP;
  	rcu_read_lock();
  	ops = rcu_dereference(lwtun_encaps[encap_type]);
  #ifdef CONFIG_MODULES
  	if (!ops) {
  		const char *encap_type_str = lwtunnel_encap_str(encap_type);
  
  		if (encap_type_str) {
  			rcu_read_unlock();
  			request_module("rtnl-lwt-%s", encap_type_str);
  			rcu_read_lock();
  			ops = rcu_dereference(lwtun_encaps[encap_type]);
  		}
  	}
  #endif
  	if (likely(ops && ops->build_state))
  		ret = ops->build_state(dev, encap, family, cfg, lws);
  	rcu_read_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL(lwtunnel_build_state);
  
  int lwtunnel_fill_encap(struct sk_buff *skb, struct lwtunnel_state *lwtstate)
  {
  	const struct lwtunnel_encap_ops *ops;
  	struct nlattr *nest;
  	int ret = -EINVAL;
  
  	if (!lwtstate)
  		return 0;
  
  	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
  	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
  		return 0;
  
  	ret = -EOPNOTSUPP;
  	nest = nla_nest_start(skb, RTA_ENCAP);
  	rcu_read_lock();
  	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
  	if (likely(ops && ops->fill_encap))
  		ret = ops->fill_encap(skb, lwtstate);
  	rcu_read_unlock();
  
  	if (ret)
  		goto nla_put_failure;
  	nla_nest_end(skb, nest);
  	ret = nla_put_u16(skb, RTA_ENCAP_TYPE, lwtstate->type);
  	if (ret)
  		goto nla_put_failure;
  
  	return 0;
  
  nla_put_failure:
  	nla_nest_cancel(skb, nest);
  
  	return (ret == -EOPNOTSUPP ? 0 : ret);
  }
  EXPORT_SYMBOL(lwtunnel_fill_encap);
  
  int lwtunnel_get_encap_size(struct lwtunnel_state *lwtstate)
  {
  	const struct lwtunnel_encap_ops *ops;
  	int ret = 0;
  
  	if (!lwtstate)
  		return 0;
  
  	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
  	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
  		return 0;
  
  	rcu_read_lock();
  	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
  	if (likely(ops && ops->get_encap_size))
  		ret = nla_total_size(ops->get_encap_size(lwtstate));
  	rcu_read_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL(lwtunnel_get_encap_size);
  
  int lwtunnel_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
  {
  	const struct lwtunnel_encap_ops *ops;
  	int ret = 0;
  
  	if (!a && !b)
  		return 0;
  
  	if (!a || !b)
  		return 1;
  
  	if (a->type != b->type)
  		return 1;
  
  	if (a->type == LWTUNNEL_ENCAP_NONE ||
  	    a->type > LWTUNNEL_ENCAP_MAX)
  		return 0;
  
  	rcu_read_lock();
  	ops = rcu_dereference(lwtun_encaps[a->type]);
  	if (likely(ops && ops->cmp_encap))
  		ret = ops->cmp_encap(a, b);
  	rcu_read_unlock();
  
  	return ret;
  }
  EXPORT_SYMBOL(lwtunnel_cmp_encap);
  
  int lwtunnel_output(struct net *net, struct sock *sk, struct sk_buff *skb)
  {
  	struct dst_entry *dst = skb_dst(skb);
  	const struct lwtunnel_encap_ops *ops;
  	struct lwtunnel_state *lwtstate;
  	int ret = -EINVAL;
  
  	if (!dst)
  		goto drop;
  	lwtstate = dst->lwtstate;
  
  	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
  	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
  		return 0;
  
  	ret = -EOPNOTSUPP;
  	rcu_read_lock();
  	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
  	if (likely(ops && ops->output))
  		ret = ops->output(net, sk, skb);
  	rcu_read_unlock();
  
  	if (ret == -EOPNOTSUPP)
  		goto drop;
  
  	return ret;
  
  drop:
  	kfree_skb(skb);
  
  	return ret;
  }
  EXPORT_SYMBOL(lwtunnel_output);
  
  int lwtunnel_input(struct sk_buff *skb)
  {
  	struct dst_entry *dst = skb_dst(skb);
  	const struct lwtunnel_encap_ops *ops;
  	struct lwtunnel_state *lwtstate;
  	int ret = -EINVAL;
  
  	if (!dst)
  		goto drop;
  	lwtstate = dst->lwtstate;
  
  	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
  	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
  		return 0;
  
  	ret = -EOPNOTSUPP;
  	rcu_read_lock();
  	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
  	if (likely(ops && ops->input))
  		ret = ops->input(skb);
  	rcu_read_unlock();
  
  	if (ret == -EOPNOTSUPP)
  		goto drop;
  
  	return ret;
  
  drop:
  	kfree_skb(skb);
  
  	return ret;
  }
  EXPORT_SYMBOL(lwtunnel_input);
  