/*
   * net/sched/em_meta.c	Metadata ematch
   *
   *		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.
   *
   * Authors:	Thomas Graf <tgraf@suug.ch>
   *
   * ==========================================================================

   *

   * 	The metadata ematch compares two meta objects where each object
   * 	represents either a meta value stored in the kernel or a static
   * 	value provided by userspace. The objects are not provided by
   * 	userspace itself but rather a definition providing the information
   * 	to build them. Every object is of a certain type which must be
   * 	equal to the object it is being compared to.
   *
   * 	The definition of a objects conists of the type (meta type), a
   * 	identifier (meta id) and additional type specific information.
   * 	The meta id is either TCF_META_TYPE_VALUE for values provided by
   * 	userspace or a index to the meta operations table consisting of
   * 	function pointers to type specific meta data collectors returning
   * 	the value of the requested meta value.
   *
   * 	         lvalue                                   rvalue
   * 	      +-----------+                           +-----------+
   * 	      | type: INT |                           | type: INT |

   * 	 def  | id: DEV   |                           | id: VALUE |

   * 	      | data:     |                           | data: 3   |
   * 	      +-----------+                           +-----------+
   * 	            |                                       |

   * 	            ---> meta_ops[INT][DEV](...)            |

   *	                      |                             |

   * 	            -----------                             |
   * 	            V                                       V
   * 	      +-----------+                           +-----------+
   * 	      | type: INT |                           | type: INT |

   * 	 obj  | id: DEV |                             | id: VALUE |

   * 	      | data: 2   |<--data got filled out     | data: 3   |
   * 	      +-----------+                           +-----------+
   * 	            |                                         |
   * 	            --------------> 2  equals 3 <--------------
   *
   * 	This is a simplified schema, the complexity varies depending
   * 	on the meta type. Obviously, the length of the data must also
   * 	be provided for non-numeric types.
   *

   * 	Additionally, type dependent modifiers such as shift operators

   * 	or mask may be applied to extend the functionaliy. As of now,
   * 	the variable length type supports shifting the byte string to
   * 	the right, eating up any number of octets and thus supporting
   * 	wildcard interface name comparisons such as "ppp%" matching
   * 	ppp0..9.
   *
   * 	NOTE: Certain meta values depend on other subsystems and are

   * 	      only available if that subsystem is enabled in the kernel.

   */

  #include <linux/slab.h>

  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/string.h>
  #include <linux/skbuff.h>
  #include <linux/random.h>

  #include <linux/if_vlan.h>

  #include <linux/tc_ematch/tc_em_meta.h>
  #include <net/dst.h>
  #include <net/route.h>
  #include <net/pkt_cls.h>

  #include <net/sock.h>

  struct meta_obj {

  	unsigned long		value;
  	unsigned int		len;
  };

  struct meta_value {

  	struct tcf_meta_val	hdr;
  	unsigned long		val;
  	unsigned int		len;
  };

  struct meta_match {

  	struct meta_value	lvalue;
  	struct meta_value	rvalue;
  };
  
  static inline int meta_id(struct meta_value *v)
  {
  	return TCF_META_ID(v->hdr.kind);
  }
  
  static inline int meta_type(struct meta_value *v)
  {
  	return TCF_META_TYPE(v->hdr.kind);
  }
  
  #define META_COLLECTOR(FUNC) static void meta_##FUNC(struct sk_buff *skb, \
  	struct tcf_pkt_info *info, struct meta_value *v, \
  	struct meta_obj *dst, int *err)
  
  /**************************************************************************
   * System status & misc
   **************************************************************************/
  
  META_COLLECTOR(int_random)
  {
  	get_random_bytes(&dst->value, sizeof(dst->value));
  }
  
  static inline unsigned long fixed_loadavg(int load)
  {
  	int rnd_load = load + (FIXED_1/200);
  	int rnd_frac = ((rnd_load & (FIXED_1-1)) * 100) >> FSHIFT;
  
  	return ((rnd_load >> FSHIFT) * 100) + rnd_frac;
  }
  
  META_COLLECTOR(int_loadavg_0)
  {
  	dst->value = fixed_loadavg(avenrun[0]);
  }
  
  META_COLLECTOR(int_loadavg_1)
  {
  	dst->value = fixed_loadavg(avenrun[1]);
  }
  
  META_COLLECTOR(int_loadavg_2)
  {
  	dst->value = fixed_loadavg(avenrun[2]);
  }
  
  /**************************************************************************
   * Device names & indices
   **************************************************************************/
  
  static inline int int_dev(struct net_device *dev, struct meta_obj *dst)
  {
  	if (unlikely(dev == NULL))
  		return -1;
  
  	dst->value = dev->ifindex;
  	return 0;
  }
  
  static inline int var_dev(struct net_device *dev, struct meta_obj *dst)
  {
  	if (unlikely(dev == NULL))
  		return -1;
  
  	dst->value = (unsigned long) dev->name;
  	dst->len = strlen(dev->name);
  	return 0;
  }
  
  META_COLLECTOR(int_dev)
  {
  	*err = int_dev(skb->dev, dst);
  }
  
  META_COLLECTOR(var_dev)
  {
  	*err = var_dev(skb->dev, dst);
  }

  /**************************************************************************

   * vlan tag
   **************************************************************************/
  
  META_COLLECTOR(int_vlan_tag)
  {

  	unsigned short tag;
  
  	tag = vlan_tx_tag_get(skb);
  	if (!tag && __vlan_get_tag(skb, &tag))

  		*err = -1;
  	else
  		dst->value = tag;
  }
  
  
  
  /**************************************************************************

   * skb attributes
   **************************************************************************/
  
  META_COLLECTOR(int_priority)
  {
  	dst->value = skb->priority;
  }
  
  META_COLLECTOR(int_protocol)
  {
  	/* Let userspace take care of the byte ordering */
  	dst->value = skb->protocol;
  }

  META_COLLECTOR(int_pkttype)
  {
  	dst->value = skb->pkt_type;
  }
  
  META_COLLECTOR(int_pktlen)
  {
  	dst->value = skb->len;
  }
  
  META_COLLECTOR(int_datalen)
  {
  	dst->value = skb->data_len;
  }
  
  META_COLLECTOR(int_maclen)
  {
  	dst->value = skb->mac_len;
  }

  META_COLLECTOR(int_rxhash)
  {
  	dst->value = skb_get_rxhash(skb);
  }

  /**************************************************************************
   * Netfilter
   **************************************************************************/

  META_COLLECTOR(int_mark)

  {

  	dst->value = skb->mark;

  }

  
  /**************************************************************************
   * Traffic Control
   **************************************************************************/
  
  META_COLLECTOR(int_tcindex)
  {
  	dst->value = skb->tc_index;
  }

  /**************************************************************************
   * Routing
   **************************************************************************/

  META_COLLECTOR(int_rtclassid)
  {

  	if (unlikely(skb_dst(skb) == NULL))

  		*err = -1;
  	else

  #ifdef CONFIG_IP_ROUTE_CLASSID

  		dst->value = skb_dst(skb)->tclassid;

  #else
  		dst->value = 0;

  #endif

  }

  
  META_COLLECTOR(int_rtiif)
  {

  	if (unlikely(skb_rtable(skb) == NULL))

  		*err = -1;
  	else

  		dst->value = skb_rtable(skb)->rt_iif;

  }
  
  /**************************************************************************

   * Socket Attributes
   **************************************************************************/
  
  #define SKIP_NONLOCAL(skb)			\
  	if (unlikely(skb->sk == NULL)) {	\
  		*err = -1;			\
  		return;				\
  	}
  
  META_COLLECTOR(int_sk_family)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_family;
  }
  
  META_COLLECTOR(int_sk_state)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_state;
  }
  
  META_COLLECTOR(int_sk_reuse)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_reuse;
  }
  
  META_COLLECTOR(int_sk_bound_if)
  {
  	SKIP_NONLOCAL(skb);
  	/* No error if bound_dev_if is 0, legal userspace check */
  	dst->value = skb->sk->sk_bound_dev_if;
  }
  
  META_COLLECTOR(var_sk_bound_if)
  {
  	SKIP_NONLOCAL(skb);

  	if (skb->sk->sk_bound_dev_if == 0) {

  		dst->value = (unsigned long) "any";
  		dst->len = 3;

  	} else {

  		struct net_device *dev;

  		rcu_read_lock();

  		dev = dev_get_by_index_rcu(sock_net(skb->sk),
  					   skb->sk->sk_bound_dev_if);

  		*err = var_dev(dev, dst);

  		rcu_read_unlock();
  	}

  }
  
  META_COLLECTOR(int_sk_refcnt)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = atomic_read(&skb->sk->sk_refcnt);
  }
  
  META_COLLECTOR(int_sk_rcvbuf)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_rcvbuf;
  }
  
  META_COLLECTOR(int_sk_shutdown)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_shutdown;
  }
  
  META_COLLECTOR(int_sk_proto)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_protocol;
  }
  
  META_COLLECTOR(int_sk_type)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_type;
  }
  
  META_COLLECTOR(int_sk_rmem_alloc)
  {
  	SKIP_NONLOCAL(skb);

  	dst->value = sk_rmem_alloc_get(skb->sk);

  }
  
  META_COLLECTOR(int_sk_wmem_alloc)
  {
  	SKIP_NONLOCAL(skb);

  	dst->value = sk_wmem_alloc_get(skb->sk);

  }
  
  META_COLLECTOR(int_sk_omem_alloc)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = atomic_read(&skb->sk->sk_omem_alloc);
  }
  
  META_COLLECTOR(int_sk_rcv_qlen)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_receive_queue.qlen;
  }
  
  META_COLLECTOR(int_sk_snd_qlen)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_write_queue.qlen;
  }
  
  META_COLLECTOR(int_sk_wmem_queued)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_wmem_queued;
  }
  
  META_COLLECTOR(int_sk_fwd_alloc)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_forward_alloc;
  }
  
  META_COLLECTOR(int_sk_sndbuf)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_sndbuf;
  }
  
  META_COLLECTOR(int_sk_alloc)
  {
  	SKIP_NONLOCAL(skb);

  	dst->value = (__force int) skb->sk->sk_allocation;

  }

  META_COLLECTOR(int_sk_hash)

  {
  	SKIP_NONLOCAL(skb);

  	dst->value = skb->sk->sk_hash;

  }
  
  META_COLLECTOR(int_sk_lingertime)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_lingertime / HZ;
  }
  
  META_COLLECTOR(int_sk_err_qlen)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_error_queue.qlen;
  }
  
  META_COLLECTOR(int_sk_ack_bl)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_ack_backlog;
  }
  
  META_COLLECTOR(int_sk_max_ack_bl)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_max_ack_backlog;
  }
  
  META_COLLECTOR(int_sk_prio)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_priority;
  }
  
  META_COLLECTOR(int_sk_rcvlowat)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_rcvlowat;
  }
  
  META_COLLECTOR(int_sk_rcvtimeo)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_rcvtimeo / HZ;
  }
  
  META_COLLECTOR(int_sk_sndtimeo)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_sndtimeo / HZ;
  }
  
  META_COLLECTOR(int_sk_sendmsg_off)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_sndmsg_off;
  }
  
  META_COLLECTOR(int_sk_write_pend)
  {
  	SKIP_NONLOCAL(skb);
  	dst->value = skb->sk->sk_write_pending;
  }
  
  /**************************************************************************

   * Meta value collectors assignment table
   **************************************************************************/

  struct meta_ops {

  	void		(*get)(struct sk_buff *, struct tcf_pkt_info *,
  			       struct meta_value *, struct meta_obj *, int *);
  };

  #define META_ID(name) TCF_META_ID_##name
  #define META_FUNC(name) { .get = meta_##name }

  /* Meta value operations table listing all meta value collectors and
   * assigns them to a type and meta id. */

  static struct meta_ops __meta_ops[TCF_META_TYPE_MAX + 1][TCF_META_ID_MAX + 1] = {

  	[TCF_META_TYPE_VAR] = {

  		[META_ID(DEV)]			= META_FUNC(var_dev),

  		[META_ID(SK_BOUND_IF)] 		= META_FUNC(var_sk_bound_if),

  	},
  	[TCF_META_TYPE_INT] = {

  		[META_ID(RANDOM)]		= META_FUNC(int_random),
  		[META_ID(LOADAVG_0)]		= META_FUNC(int_loadavg_0),
  		[META_ID(LOADAVG_1)]		= META_FUNC(int_loadavg_1),
  		[META_ID(LOADAVG_2)]		= META_FUNC(int_loadavg_2),
  		[META_ID(DEV)]			= META_FUNC(int_dev),

  		[META_ID(PRIORITY)]		= META_FUNC(int_priority),
  		[META_ID(PROTOCOL)]		= META_FUNC(int_protocol),

  		[META_ID(PKTTYPE)]		= META_FUNC(int_pkttype),
  		[META_ID(PKTLEN)]		= META_FUNC(int_pktlen),
  		[META_ID(DATALEN)]		= META_FUNC(int_datalen),
  		[META_ID(MACLEN)]		= META_FUNC(int_maclen),

  		[META_ID(NFMARK)]		= META_FUNC(int_mark),

  		[META_ID(TCINDEX)]		= META_FUNC(int_tcindex),

  		[META_ID(RTCLASSID)]		= META_FUNC(int_rtclassid),

  		[META_ID(RTIIF)]		= META_FUNC(int_rtiif),
  		[META_ID(SK_FAMILY)]		= META_FUNC(int_sk_family),
  		[META_ID(SK_STATE)]		= META_FUNC(int_sk_state),
  		[META_ID(SK_REUSE)]		= META_FUNC(int_sk_reuse),
  		[META_ID(SK_BOUND_IF)]		= META_FUNC(int_sk_bound_if),
  		[META_ID(SK_REFCNT)]		= META_FUNC(int_sk_refcnt),
  		[META_ID(SK_RCVBUF)]		= META_FUNC(int_sk_rcvbuf),
  		[META_ID(SK_SNDBUF)]		= META_FUNC(int_sk_sndbuf),
  		[META_ID(SK_SHUTDOWN)]		= META_FUNC(int_sk_shutdown),
  		[META_ID(SK_PROTO)]		= META_FUNC(int_sk_proto),
  		[META_ID(SK_TYPE)]		= META_FUNC(int_sk_type),
  		[META_ID(SK_RMEM_ALLOC)]	= META_FUNC(int_sk_rmem_alloc),
  		[META_ID(SK_WMEM_ALLOC)]	= META_FUNC(int_sk_wmem_alloc),
  		[META_ID(SK_OMEM_ALLOC)]	= META_FUNC(int_sk_omem_alloc),
  		[META_ID(SK_WMEM_QUEUED)]	= META_FUNC(int_sk_wmem_queued),
  		[META_ID(SK_RCV_QLEN)]		= META_FUNC(int_sk_rcv_qlen),
  		[META_ID(SK_SND_QLEN)]		= META_FUNC(int_sk_snd_qlen),
  		[META_ID(SK_ERR_QLEN)]		= META_FUNC(int_sk_err_qlen),
  		[META_ID(SK_FORWARD_ALLOCS)]	= META_FUNC(int_sk_fwd_alloc),
  		[META_ID(SK_ALLOCS)]		= META_FUNC(int_sk_alloc),

  		[META_ID(SK_HASH)]		= META_FUNC(int_sk_hash),

  		[META_ID(SK_LINGERTIME)]	= META_FUNC(int_sk_lingertime),
  		[META_ID(SK_ACK_BACKLOG)]	= META_FUNC(int_sk_ack_bl),
  		[META_ID(SK_MAX_ACK_BACKLOG)]	= META_FUNC(int_sk_max_ack_bl),
  		[META_ID(SK_PRIO)]		= META_FUNC(int_sk_prio),
  		[META_ID(SK_RCVLOWAT)]		= META_FUNC(int_sk_rcvlowat),
  		[META_ID(SK_RCVTIMEO)]		= META_FUNC(int_sk_rcvtimeo),
  		[META_ID(SK_SNDTIMEO)]		= META_FUNC(int_sk_sndtimeo),
  		[META_ID(SK_SENDMSG_OFF)]	= META_FUNC(int_sk_sendmsg_off),
  		[META_ID(SK_WRITE_PENDING)]	= META_FUNC(int_sk_write_pend),

  		[META_ID(VLAN_TAG)]		= META_FUNC(int_vlan_tag),

  		[META_ID(RXHASH)]		= META_FUNC(int_rxhash),

  	}
  };

  static inline struct meta_ops *meta_ops(struct meta_value *val)

  {
  	return &__meta_ops[meta_type(val)][meta_id(val)];
  }
  
  /**************************************************************************
   * Type specific operations for TCF_META_TYPE_VAR
   **************************************************************************/
  
  static int meta_var_compare(struct meta_obj *a, struct meta_obj *b)
  {
  	int r = a->len - b->len;
  
  	if (r == 0)
  		r = memcmp((void *) a->value, (void *) b->value, a->len);
  
  	return r;
  }

  static int meta_var_change(struct meta_value *dst, struct nlattr *nla)

  {

  	int len = nla_len(nla);

  	dst->val = (unsigned long)kmemdup(nla_data(nla), len, GFP_KERNEL);

  	if (dst->val == 0UL)
  		return -ENOMEM;

  	dst->len = len;
  	return 0;
  }
  
  static void meta_var_destroy(struct meta_value *v)
  {

  	kfree((void *) v->val);

  }
  
  static void meta_var_apply_extras(struct meta_value *v,
  				  struct meta_obj *dst)
  {
  	int shift = v->hdr.shift;
  
  	if (shift && shift < dst->len)
  		dst->len -= shift;
  }
  
  static int meta_var_dump(struct sk_buff *skb, struct meta_value *v, int tlv)
  {
  	if (v->val && v->len)

  		NLA_PUT(skb, tlv, v->len, (void *) v->val);

  	return 0;

  nla_put_failure:

  	return -1;
  }
  
  /**************************************************************************
   * Type specific operations for TCF_META_TYPE_INT
   **************************************************************************/
  
  static int meta_int_compare(struct meta_obj *a, struct meta_obj *b)
  {
  	/* Let gcc optimize it, the unlikely is not really based on
  	 * some numbers but jump free code for mismatches seems
  	 * more logical. */

  	if (unlikely(a->value == b->value))

  		return 0;

  	else if (a->value < b->value)

  		return -1;
  	else
  		return 1;
  }

  static int meta_int_change(struct meta_value *dst, struct nlattr *nla)

  {

  	if (nla_len(nla) >= sizeof(unsigned long)) {
  		dst->val = *(unsigned long *) nla_data(nla);

  		dst->len = sizeof(unsigned long);

  	} else if (nla_len(nla) == sizeof(u32)) {

  		dst->val = nla_get_u32(nla);

  		dst->len = sizeof(u32);
  	} else
  		return -EINVAL;
  
  	return 0;
  }
  
  static void meta_int_apply_extras(struct meta_value *v,
  				  struct meta_obj *dst)
  {
  	if (v->hdr.shift)
  		dst->value >>= v->hdr.shift;
  
  	if (v->val)
  		dst->value &= v->val;
  }
  
  static int meta_int_dump(struct sk_buff *skb, struct meta_value *v, int tlv)
  {
  	if (v->len == sizeof(unsigned long))

  		NLA_PUT(skb, tlv, sizeof(unsigned long), &v->val);

  	else if (v->len == sizeof(u32))

  		NLA_PUT_U32(skb, tlv, v->val);

  
  	return 0;

  nla_put_failure:

  	return -1;
  }
  
  /**************************************************************************
   * Type specific operations table
   **************************************************************************/

  struct meta_type_ops {

  	void	(*destroy)(struct meta_value *);
  	int	(*compare)(struct meta_obj *, struct meta_obj *);

  	int	(*change)(struct meta_value *, struct nlattr *);

  	void	(*apply_extras)(struct meta_value *, struct meta_obj *);
  	int	(*dump)(struct sk_buff *, struct meta_value *, int);
  };

  static struct meta_type_ops __meta_type_ops[TCF_META_TYPE_MAX + 1] = {

  	[TCF_META_TYPE_VAR] = {
  		.destroy = meta_var_destroy,
  		.compare = meta_var_compare,
  		.change = meta_var_change,
  		.apply_extras = meta_var_apply_extras,
  		.dump = meta_var_dump
  	},
  	[TCF_META_TYPE_INT] = {
  		.compare = meta_int_compare,
  		.change = meta_int_change,
  		.apply_extras = meta_int_apply_extras,
  		.dump = meta_int_dump
  	}
  };

  static inline struct meta_type_ops *meta_type_ops(struct meta_value *v)

  {
  	return &__meta_type_ops[meta_type(v)];
  }
  
  /**************************************************************************
   * Core
   **************************************************************************/

  static int meta_get(struct sk_buff *skb, struct tcf_pkt_info *info,
  		    struct meta_value *v, struct meta_obj *dst)

  {
  	int err = 0;
  
  	if (meta_id(v) == TCF_META_ID_VALUE) {
  		dst->value = v->val;
  		dst->len = v->len;
  		return 0;
  	}
  
  	meta_ops(v)->get(skb, info, v, dst, &err);
  	if (err < 0)
  		return err;
  
  	if (meta_type_ops(v)->apply_extras)

  		meta_type_ops(v)->apply_extras(v, dst);

  
  	return 0;
  }
  
  static int em_meta_match(struct sk_buff *skb, struct tcf_ematch *m,
  			 struct tcf_pkt_info *info)
  {
  	int r;
  	struct meta_match *meta = (struct meta_match *) m->data;
  	struct meta_obj l_value, r_value;
  
  	if (meta_get(skb, info, &meta->lvalue, &l_value) < 0 ||
  	    meta_get(skb, info, &meta->rvalue, &r_value) < 0)
  		return 0;
  
  	r = meta_type_ops(&meta->lvalue)->compare(&l_value, &r_value);
  
  	switch (meta->lvalue.hdr.op) {

  	case TCF_EM_OPND_EQ:
  		return !r;
  	case TCF_EM_OPND_LT:
  		return r < 0;
  	case TCF_EM_OPND_GT:
  		return r > 0;

  	}
  
  	return 0;
  }

  static void meta_delete(struct meta_match *meta)

  {

  	if (meta) {
  		struct meta_type_ops *ops = meta_type_ops(&meta->lvalue);

  		if (ops && ops->destroy) {
  			ops->destroy(&meta->lvalue);
  			ops->destroy(&meta->rvalue);
  		}

  	}
  
  	kfree(meta);
  }

  static inline int meta_change_data(struct meta_value *dst, struct nlattr *nla)

  {

  	if (nla) {
  		if (nla_len(nla) == 0)

  			return -EINVAL;

  		return meta_type_ops(dst)->change(dst, nla);

  	}
  
  	return 0;
  }
  
  static inline int meta_is_supported(struct meta_value *val)
  {

  	return !meta_id(val) || meta_ops(val)->get;

  }

  static const struct nla_policy meta_policy[TCA_EM_META_MAX + 1] = {
  	[TCA_EM_META_HDR]	= { .len = sizeof(struct tcf_meta_hdr) },
  };

  static int em_meta_change(struct tcf_proto *tp, void *data, int len,
  			  struct tcf_ematch *m)
  {

  	int err;

  	struct nlattr *tb[TCA_EM_META_MAX + 1];

  	struct tcf_meta_hdr *hdr;
  	struct meta_match *meta = NULL;

  	err = nla_parse(tb, TCA_EM_META_MAX, data, len, meta_policy);

  	if (err < 0)

  		goto errout;

  	err = -EINVAL;

  	if (tb[TCA_EM_META_HDR] == NULL)

  		goto errout;

  	hdr = nla_data(tb[TCA_EM_META_HDR]);

  
  	if (TCF_META_TYPE(hdr->left.kind) != TCF_META_TYPE(hdr->right.kind) ||
  	    TCF_META_TYPE(hdr->left.kind) > TCF_META_TYPE_MAX ||
  	    TCF_META_ID(hdr->left.kind) > TCF_META_ID_MAX ||
  	    TCF_META_ID(hdr->right.kind) > TCF_META_ID_MAX)
  		goto errout;

  	meta = kzalloc(sizeof(*meta), GFP_KERNEL);

  	if (meta == NULL)
  		goto errout;

  
  	memcpy(&meta->lvalue.hdr, &hdr->left, sizeof(hdr->left));
  	memcpy(&meta->rvalue.hdr, &hdr->right, sizeof(hdr->right));
  
  	if (!meta_is_supported(&meta->lvalue) ||
  	    !meta_is_supported(&meta->rvalue)) {
  		err = -EOPNOTSUPP;
  		goto errout;
  	}

  	if (meta_change_data(&meta->lvalue, tb[TCA_EM_META_LVALUE]) < 0 ||
  	    meta_change_data(&meta->rvalue, tb[TCA_EM_META_RVALUE]) < 0)

  		goto errout;
  
  	m->datalen = sizeof(*meta);
  	m->data = (unsigned long) meta;
  
  	err = 0;
  errout:
  	if (err && meta)
  		meta_delete(meta);
  	return err;
  }
  
  static void em_meta_destroy(struct tcf_proto *tp, struct tcf_ematch *m)
  {
  	if (m)
  		meta_delete((struct meta_match *) m->data);
  }
  
  static int em_meta_dump(struct sk_buff *skb, struct tcf_ematch *em)
  {
  	struct meta_match *meta = (struct meta_match *) em->data;
  	struct tcf_meta_hdr hdr;
  	struct meta_type_ops *ops;
  
  	memset(&hdr, 0, sizeof(hdr));
  	memcpy(&hdr.left, &meta->lvalue.hdr, sizeof(hdr.left));
  	memcpy(&hdr.right, &meta->rvalue.hdr, sizeof(hdr.right));

  	NLA_PUT(skb, TCA_EM_META_HDR, sizeof(hdr), &hdr);

  
  	ops = meta_type_ops(&meta->lvalue);
  	if (ops->dump(skb, &meta->lvalue, TCA_EM_META_LVALUE) < 0 ||
  	    ops->dump(skb, &meta->rvalue, TCA_EM_META_RVALUE) < 0)

  		goto nla_put_failure;

  
  	return 0;

  nla_put_failure:

  	return -1;

  }

  
  static struct tcf_ematch_ops em_meta_ops = {
  	.kind	  = TCF_EM_META,
  	.change	  = em_meta_change,
  	.match	  = em_meta_match,
  	.destroy  = em_meta_destroy,
  	.dump	  = em_meta_dump,
  	.owner	  = THIS_MODULE,
  	.link	  = LIST_HEAD_INIT(em_meta_ops.link)
  };
  
  static int __init init_em_meta(void)
  {
  	return tcf_em_register(&em_meta_ops);
  }

  static void __exit exit_em_meta(void)

  {
  	tcf_em_unregister(&em_meta_ops);
  }
  
  MODULE_LICENSE("GPL");
  
  module_init(init_em_meta);
  module_exit(exit_em_meta);

  
  MODULE_ALIAS_TCF_EMATCH(TCF_EM_META);