text: /*
   * 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, struct tc_action *a,
  		     struct tcf_result *res)
  {
  	struct tcf_pedit *p = a->priv;
  	int i, munged = 0;
  	u8 *pptr;
  
  	if (!(skb->tc_verd & TC_OK2MUNGE)) {
  		/* should we set skb->cloned? */
  		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
  			return p->tcf_action;
  		}
  	}
  
  	pptr = skb_network_header(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;
  			int offset = tkey->off;
  
  			if (tkey->offmask) {
  				if (skb->len > tkey->at) {
  					 char *j = pptr + tkey->at;
  					 offset += ((*j & tkey->offmask) >>
  						   tkey->shift);
  				} else {
  					goto bad;
  				}
  			}
  
  			if (offset % 4) {
  				printk("offset must be on 32 bit boundaries\n");
  				goto bad;
  			}
  			if (offset > 0 && offset > skb->len) {
  				printk("offset %d cant exceed pkt length %d\n",
  				       offset, skb->len);
  				goto bad;
  			}
  
  			ptr = (u32 *)(pptr+offset);
  			/* just do it, baby */
  			*ptr = ((*ptr & tkey->mask) ^ tkey->val);
  			munged++;
  		}
  
  		if (munged)
  			skb->tc_verd = SET_TC_MUNGED(skb->tc_verd);
  		goto done;
  	} else {
  		printk("pedit BUG: index %d\n", p->tcf_index);
  	}
  
  bad:
  	p->tcf_qstats.overlimits++;
  done:
  	p->tcf_bstats.bytes += qdisc_pkt_len(skb);
  	p->tcf_bstats.packets++;
  	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);
  
  