/*
   * net/sched/pedit.c	Generic packet editor
   *
   *		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:	Jamal Hadi Salim (2002-4)
   */

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

  #include <linux/string.h>

  #include <linux/errno.h>

  #include <linux/skbuff.h>
  #include <linux/rtnetlink.h>
  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/slab.h>

  #include <net/netlink.h>

  #include <net/pkt_sched.h>
  #include <linux/tc_act/tc_pedit.h>
  #include <net/tc_act/tc_pedit.h>

  #define PEDIT_TAB_MASK	15
  static struct tcf_common *tcf_pedit_ht[PEDIT_TAB_MASK + 1];
  static u32 pedit_idx_gen;

  static DEFINE_RWLOCK(pedit_lock);

  static struct tcf_hashinfo pedit_hash_info = {
  	.htab	=	tcf_pedit_ht,
  	.hmask	=	PEDIT_TAB_MASK,
  	.lock	=	&pedit_lock,
  };

  static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {

  	[TCA_PEDIT_PARMS]	= { .len = sizeof(struct tc_pedit) },

  };

  static int tcf_pedit_init(struct nlattr *nla, struct nlattr *est,

  			  struct tc_action *a, int ovr, int bind)

  {

  	struct nlattr *tb[TCA_PEDIT_MAX + 1];

  	struct tc_pedit *parm;

  	int ret = 0, err;

  	struct tcf_pedit *p;

  	struct tcf_common *pc;

  	struct tc_pedit_key *keys = NULL;
  	int ksize;

  	if (nla == NULL)

  		return -EINVAL;

  	err = nla_parse_nested(tb, TCA_PEDIT_MAX, nla, pedit_policy);

  	if (err < 0)
  		return err;

  	if (tb[TCA_PEDIT_PARMS] == NULL)

  		return -EINVAL;

  	parm = nla_data(tb[TCA_PEDIT_PARMS]);

  	ksize = parm->nkeys * sizeof(struct tc_pedit_key);

  	if (nla_len(tb[TCA_PEDIT_PARMS]) < sizeof(*parm) + ksize)

  		return -EINVAL;

  	pc = tcf_hash_check(parm->index, a, bind, &pedit_hash_info);
  	if (!pc) {

  		if (!parm->nkeys)
  			return -EINVAL;

  		pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
  				     &pedit_idx_gen, &pedit_hash_info);

  		if (IS_ERR(pc))

  			return PTR_ERR(pc);

  		p = to_pedit(pc);

  		keys = kmalloc(ksize, GFP_KERNEL);
  		if (keys == NULL) {

  			kfree(pc);

  			return -ENOMEM;
  		}
  		ret = ACT_P_CREATED;
  	} else {

  		p = to_pedit(pc);

  		if (!ovr) {

  			tcf_hash_release(pc, bind, &pedit_hash_info);

  			return -EEXIST;
  		}

  		if (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys) {

  			keys = kmalloc(ksize, GFP_KERNEL);
  			if (keys == NULL)
  				return -ENOMEM;
  		}
  	}

  	spin_lock_bh(&p->tcf_lock);
  	p->tcfp_flags = parm->flags;
  	p->tcf_action = parm->action;

  	if (keys) {

  		kfree(p->tcfp_keys);
  		p->tcfp_keys = keys;
  		p->tcfp_nkeys = parm->nkeys;

  	}

  	memcpy(p->tcfp_keys, parm->keys, ksize);
  	spin_unlock_bh(&p->tcf_lock);

  	if (ret == ACT_P_CREATED)

  		tcf_hash_insert(pc, &pedit_hash_info);

  	return ret;
  }

  static int tcf_pedit_cleanup(struct tc_action *a, int bind)

  {

  	struct tcf_pedit *p = a->priv;

  	if (p) {
  		struct tc_pedit_key *keys = p->tcfp_keys;
  		if (tcf_hash_release(&p->common, bind, &pedit_hash_info)) {

  			kfree(keys);
  			return 1;
  		}
  	}
  	return 0;
  }

  static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a,

  		     struct tcf_result *res)

  {

  	struct tcf_pedit *p = a->priv;

  	int i, munged = 0;

  	unsigned int off;

  	if (skb_cloned(skb) &&
  	    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
  		return p->tcf_action;

  	off = skb_network_offset(skb);

  	spin_lock(&p->tcf_lock);

  	p->tcf_tm.lastuse = jiffies;

  	if (p->tcfp_nkeys > 0) {
  		struct tc_pedit_key *tkey = p->tcfp_keys;

  		for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {

  			u32 *ptr, _data;

  			int offset = tkey->off;
  
  			if (tkey->offmask) {

  				char *d, _d;
  
  				d = skb_header_pointer(skb, off + tkey->at, 1,
  						       &_d);
  				if (!d)

  					goto bad;

  				offset += (*d & tkey->offmask) >> tkey->shift;

  			}
  
  			if (offset % 4) {

  				pr_info("tc filter pedit"
  					" offset must be on 32 bit boundaries
  ");

  				goto bad;
  			}

  			if (offset > 0 && offset > skb->len) {

  				pr_info("tc filter pedit"

  					" offset %d can't exceed pkt length %d
  ",

  				       offset, skb->len);
  				goto bad;
  			}

  			ptr = skb_header_pointer(skb, off + offset, 4, &_data);
  			if (!ptr)
  				goto bad;

  			/* just do it, baby */
  			*ptr = ((*ptr & tkey->mask) ^ tkey->val);

  			if (ptr == &_data)
  				skb_store_bits(skb, off + offset, ptr, 4);

  			munged++;
  		}

  		if (munged)
  			skb->tc_verd = SET_TC_MUNGED(skb->tc_verd);
  		goto done;

  	} else
  		WARN(1, "pedit BUG: index %d
  ", p->tcf_index);

  
  bad:

  	p->tcf_qstats.overlimits++;

  done:

  	bstats_update(&p->tcf_bstats, skb);

  	spin_unlock(&p->tcf_lock);
  	return p->tcf_action;

  }

  static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
  			  int bind, int ref)

  {

  	unsigned char *b = skb_tail_pointer(skb);

  	struct tcf_pedit *p = a->priv;

  	struct tc_pedit *opt;

  	struct tcf_t t;

  	int s;

  	s = sizeof(*opt) + p->tcfp_nkeys * sizeof(struct tc_pedit_key);

  
  	/* netlink spinlocks held above us - must use ATOMIC */

  	opt = kzalloc(s, GFP_ATOMIC);

  	if (unlikely(!opt))

  		return -ENOBUFS;

  	memcpy(opt->keys, p->tcfp_keys,
  	       p->tcfp_nkeys * sizeof(struct tc_pedit_key));
  	opt->index = p->tcf_index;
  	opt->nkeys = p->tcfp_nkeys;
  	opt->flags = p->tcfp_flags;
  	opt->action = p->tcf_action;
  	opt->refcnt = p->tcf_refcnt - ref;
  	opt->bindcnt = p->tcf_bindcnt - bind;

  	NLA_PUT(skb, TCA_PEDIT_PARMS, s, opt);

  	t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
  	t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
  	t.expires = jiffies_to_clock_t(p->tcf_tm.expires);

  	NLA_PUT(skb, TCA_PEDIT_TM, sizeof(t), &t);

  	kfree(opt);

  	return skb->len;

  nla_put_failure:

  	nlmsg_trim(skb, b);

  	kfree(opt);

  	return -1;
  }

  static struct tc_action_ops act_pedit_ops = {

  	.kind		=	"pedit",

  	.hinfo		=	&pedit_hash_info,

  	.type		=	TCA_ACT_PEDIT,
  	.capab		=	TCA_CAP_NONE,
  	.owner		=	THIS_MODULE,
  	.act		=	tcf_pedit,
  	.dump		=	tcf_pedit_dump,
  	.cleanup	=	tcf_pedit_cleanup,
  	.lookup		=	tcf_hash_search,
  	.init		=	tcf_pedit_init,
  	.walk		=	tcf_generic_walker
  };
  
  MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
  MODULE_DESCRIPTION("Generic Packet Editor actions");
  MODULE_LICENSE("GPL");

  static int __init pedit_init_module(void)

  {
  	return tcf_register_action(&act_pedit_ops);
  }

  static void __exit pedit_cleanup_module(void)

  {
  	tcf_unregister_action(&act_pedit_ops);
  }
  
  module_init(pedit_init_module);
  module_exit(pedit_cleanup_module);