text: /*
   * Packet matching code for ARP packets.
   *
   * Based heavily, if not almost entirely, upon ip_tables.c framework.
   *
   * Some ARP specific bits are:
   *
   * Copyright (C) 2002 David S. Miller (davem@redhat.com)
   * Copyright (C) 2006-2009 Patrick McHardy <kaber@trash.net>
   *
   */
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  #include <linux/kernel.h>
  #include <linux/skbuff.h>
  #include <linux/netdevice.h>
  #include <linux/capability.h>
  #include <linux/if_arp.h>
  #include <linux/kmod.h>
  #include <linux/vmalloc.h>
  #include <linux/proc_fs.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/mutex.h>
  #include <linux/err.h>
  #include <net/compat.h>
  #include <net/sock.h>
  #include <linux/uaccess.h>
  
  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter_arp/arp_tables.h>
  #include "../../netfilter/xt_repldata.h"
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  MODULE_DESCRIPTION("arptables core");
  
  void *arpt_alloc_initial_table(const struct xt_table *info)
  {
  	return xt_alloc_initial_table(arpt, ARPT);
  }
  EXPORT_SYMBOL_GPL(arpt_alloc_initial_table);
  
  static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
  				      const char *hdr_addr, int len)
  {
  	int i, ret;
  
  	if (len > ARPT_DEV_ADDR_LEN_MAX)
  		len = ARPT_DEV_ADDR_LEN_MAX;
  
  	ret = 0;
  	for (i = 0; i < len; i++)
  		ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];
  
  	return ret != 0;
  }
  
  /*
   * Unfortunately, _b and _mask are not aligned to an int (or long int)
   * Some arches dont care, unrolling the loop is a win on them.
   * For other arches, we only have a 16bit alignement.
   */
  static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
  {
  #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
  	unsigned long ret = ifname_compare_aligned(_a, _b, _mask);
  #else
  	unsigned long ret = 0;
  	const u16 *a = (const u16 *)_a;
  	const u16 *b = (const u16 *)_b;
  	const u16 *mask = (const u16 *)_mask;
  	int i;
  
  	for (i = 0; i < IFNAMSIZ/sizeof(u16); i++)
  		ret |= (a[i] ^ b[i]) & mask[i];
  #endif
  	return ret;
  }
  
  /* Returns whether packet matches rule or not. */
  static inline int arp_packet_match(const struct arphdr *arphdr,
  				   struct net_device *dev,
  				   const char *indev,
  				   const char *outdev,
  				   const struct arpt_arp *arpinfo)
  {
  	const char *arpptr = (char *)(arphdr + 1);
  	const char *src_devaddr, *tgt_devaddr;
  	__be32 src_ipaddr, tgt_ipaddr;
  	long ret;
  
  	if (NF_INVF(arpinfo, ARPT_INV_ARPOP,
  		    (arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop))
  		return 0;
  
  	if (NF_INVF(arpinfo, ARPT_INV_ARPHRD,
  		    (arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd))
  		return 0;
  
  	if (NF_INVF(arpinfo, ARPT_INV_ARPPRO,
  		    (arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro))
  		return 0;
  
  	if (NF_INVF(arpinfo, ARPT_INV_ARPHLN,
  		    (arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln))
  		return 0;
  
  	src_devaddr = arpptr;
  	arpptr += dev->addr_len;
  	memcpy(&src_ipaddr, arpptr, sizeof(u32));
  	arpptr += sizeof(u32);
  	tgt_devaddr = arpptr;
  	arpptr += dev->addr_len;
  	memcpy(&tgt_ipaddr, arpptr, sizeof(u32));
  
  	if (NF_INVF(arpinfo, ARPT_INV_SRCDEVADDR,
  		    arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr,
  					dev->addr_len)) ||
  	    NF_INVF(arpinfo, ARPT_INV_TGTDEVADDR,
  		    arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr,
  					dev->addr_len)))
  		return 0;
  
  	if (NF_INVF(arpinfo, ARPT_INV_SRCIP,
  		    (src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr) ||
  	    NF_INVF(arpinfo, ARPT_INV_TGTIP,
  		    (tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr))
  		return 0;
  
  	/* Look for ifname matches.  */
  	ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask);
  
  	if (NF_INVF(arpinfo, ARPT_INV_VIA_IN, ret != 0))
  		return 0;
  
  	ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask);
  
  	if (NF_INVF(arpinfo, ARPT_INV_VIA_OUT, ret != 0))
  		return 0;
  
  	return 1;
  }
  
  static inline int arp_checkentry(const struct arpt_arp *arp)
  {
  	if (arp->flags & ~ARPT_F_MASK)
  		return 0;
  	if (arp->invflags & ~ARPT_INV_MASK)
  		return 0;
  
  	return 1;
  }
  
  static unsigned int
  arpt_error(struct sk_buff *skb, const struct xt_action_param *par)
  {
  	net_err_ratelimited("arp_tables: error: '%s'\n",
  			    (const char *)par->targinfo);
  
  	return NF_DROP;
  }
  
  static inline const struct xt_entry_target *
  arpt_get_target_c(const struct arpt_entry *e)
  {
  	return arpt_get_target((struct arpt_entry *)e);
  }
  
  static inline struct arpt_entry *
  get_entry(const void *base, unsigned int offset)
  {
  	return (struct arpt_entry *)(base + offset);
  }
  
  static inline
  struct arpt_entry *arpt_next_entry(const struct arpt_entry *entry)
  {
  	return (void *)entry + entry->next_offset;
  }
  
  unsigned int arpt_do_table(struct sk_buff *skb,
  			   const struct nf_hook_state *state,
  			   struct xt_table *table)
  {
  	unsigned int hook = state->hook;
  	static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
  	unsigned int verdict = NF_DROP;
  	const struct arphdr *arp;
  	struct arpt_entry *e, **jumpstack;
  	const char *indev, *outdev;
  	const void *table_base;
  	unsigned int cpu, stackidx = 0;
  	const struct xt_table_info *private;
  	struct xt_action_param acpar;
  	unsigned int addend;
  
  	if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
  		return NF_DROP;
  
  	indev = state->in ? state->in->name : nulldevname;
  	outdev = state->out ? state->out->name : nulldevname;
  
  	local_bh_disable();
  	addend = xt_write_recseq_begin();
  	private = table->private;
  	cpu     = smp_processor_id();
  	/*
  	 * Ensure we load private-> members after we've fetched the base
  	 * pointer.
  	 */
  	smp_read_barrier_depends();
  	table_base = private->entries;
  	jumpstack  = (struct arpt_entry **)private->jumpstack[cpu];
  
  	/* No TEE support for arptables, so no need to switch to alternate
  	 * stack.  All targets that reenter must return absolute verdicts.
  	 */
  	e = get_entry(table_base, private->hook_entry[hook]);
  
  	acpar.state   = state;
  	acpar.hotdrop = false;
  
  	arp = arp_hdr(skb);
  	do {
  		const struct xt_entry_target *t;
  		struct xt_counters *counter;
  
  		if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
  			e = arpt_next_entry(e);
  			continue;
  		}
  
  		counter = xt_get_this_cpu_counter(&e->counters);
  		ADD_COUNTER(*counter, arp_hdr_len(skb->dev), 1);
  
  		t = arpt_get_target_c(e);
  
  		/* Standard target? */
  		if (!t->u.kernel.target->target) {
  			int v;
  
  			v = ((struct xt_standard_target *)t)->verdict;
  			if (v < 0) {
  				/* Pop from stack? */
  				if (v != XT_RETURN) {
  					verdict = (unsigned int)(-v) - 1;
  					break;
  				}
  				if (stackidx == 0) {
  					e = get_entry(table_base,
  						      private->underflow[hook]);
  				} else {
  					e = jumpstack[--stackidx];
  					e = arpt_next_entry(e);
  				}
  				continue;
  			}
  			if (table_base + v
  			    != arpt_next_entry(e)) {
  				if (unlikely(stackidx >= private->stacksize)) {
  					verdict = NF_DROP;
  					break;
  				}
  				jumpstack[stackidx++] = e;
  			}
  
  			e = get_entry(table_base, v);
  			continue;
  		}
  
  		acpar.target   = t->u.kernel.target;
  		acpar.targinfo = t->data;
  		verdict = t->u.kernel.target->target(skb, &acpar);
  
  		if (verdict == XT_CONTINUE) {
  			/* Target might have changed stuff. */
  			arp = arp_hdr(skb);
  			e = arpt_next_entry(e);
  		} else {
  			/* Verdict */
  			break;
  		}
  	} while (!acpar.hotdrop);
  	xt_write_recseq_end(addend);
  	local_bh_enable();
  
  	if (acpar.hotdrop)
  		return NF_DROP;
  	else
  		return verdict;
  }
  
  /* All zeroes == unconditional rule. */
  static inline bool unconditional(const struct arpt_entry *e)
  {
  	static const struct arpt_arp uncond;
  
  	return e->target_offset == sizeof(struct arpt_entry) &&
  	       memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
  }
  
  /* Figures out from what hook each rule can be called: returns 0 if
   * there are loops.  Puts hook bitmask in comefrom.
   */
  static int mark_source_chains(const struct xt_table_info *newinfo,
  			      unsigned int valid_hooks, void *entry0,
  			      unsigned int *offsets)
  {
  	unsigned int hook;
  
  	/* No recursion; use packet counter to save back ptrs (reset
  	 * to 0 as we leave), and comefrom to save source hook bitmask.
  	 */
  	for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
  		unsigned int pos = newinfo->hook_entry[hook];
  		struct arpt_entry *e = entry0 + pos;
  
  		if (!(valid_hooks & (1 << hook)))
  			continue;
  
  		/* Set initial back pointer. */
  		e->counters.pcnt = pos;
  
  		for (;;) {
  			const struct xt_standard_target *t
  				= (void *)arpt_get_target_c(e);
  			int visited = e->comefrom & (1 << hook);
  
  			if (e->comefrom & (1 << NF_ARP_NUMHOOKS))
  				return 0;
  
  			e->comefrom
  				|= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
  
  			/* Unconditional return/END. */
  			if ((unconditional(e) &&
  			     (strcmp(t->target.u.user.name,
  				     XT_STANDARD_TARGET) == 0) &&
  			     t->verdict < 0) || visited) {
  				unsigned int oldpos, size;
  
  				if ((strcmp(t->target.u.user.name,
  					    XT_STANDARD_TARGET) == 0) &&
  				    t->verdict < -NF_MAX_VERDICT - 1)
  					return 0;
  
  				/* Return: backtrack through the last
  				 * big jump.
  				 */
  				do {
  					e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
  					oldpos = pos;
  					pos = e->counters.pcnt;
  					e->counters.pcnt = 0;
  
  					/* We're at the start. */
  					if (pos == oldpos)
  						goto next;
  
  					e = entry0 + pos;
  				} while (oldpos == pos + e->next_offset);
  
  				/* Move along one */
  				size = e->next_offset;
  				e = entry0 + pos + size;
  				if (pos + size >= newinfo->size)
  					return 0;
  				e->counters.pcnt = pos;
  				pos += size;
  			} else {
  				int newpos = t->verdict;
  
  				if (strcmp(t->target.u.user.name,
  					   XT_STANDARD_TARGET) == 0 &&
  				    newpos >= 0) {
  					/* This a jump; chase it. */
  					if (!xt_find_jump_offset(offsets, newpos,
  								 newinfo->number))
  						return 0;
  					e = entry0 + newpos;
  				} else {
  					/* ... this is a fallthru */
  					newpos = pos + e->next_offset;
  					if (newpos >= newinfo->size)
  						return 0;
  				}
  				e = entry0 + newpos;
  				e->counters.pcnt = pos;
  				pos = newpos;
  			}
  		}
  next:		;
  	}
  	return 1;
  }
  
  static inline int check_target(struct arpt_entry *e, const char *name)
  {
  	struct xt_entry_target *t = arpt_get_target(e);
  	struct xt_tgchk_param par = {
  		.table     = name,
  		.entryinfo = e,
  		.target    = t->u.kernel.target,
  		.targinfo  = t->data,
  		.hook_mask = e->comefrom,
  		.family    = NFPROTO_ARP,
  	};
  
  	return xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
  }
  
  static inline int
  find_check_entry(struct arpt_entry *e, const char *name, unsigned int size,
  		 struct xt_percpu_counter_alloc_state *alloc_state)
  {
  	struct xt_entry_target *t;
  	struct xt_target *target;
  	int ret;
  
  	if (!xt_percpu_counter_alloc(alloc_state, &e->counters))
  		return -ENOMEM;
  
  	t = arpt_get_target(e);
  	target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
  					t->u.user.revision);
  	if (IS_ERR(target)) {
  		ret = PTR_ERR(target);
  		goto out;
  	}
  	t->u.kernel.target = target;
  
  	ret = check_target(e, name);
  	if (ret)
  		goto err;
  	return 0;
  err:
  	module_put(t->u.kernel.target->me);
  out:
  	xt_percpu_counter_free(&e->counters);
  
  	return ret;
  }
  
  static bool check_underflow(const struct arpt_entry *e)
  {
  	const struct xt_entry_target *t;
  	unsigned int verdict;
  
  	if (!unconditional(e))
  		return false;
  	t = arpt_get_target_c(e);
  	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
  		return false;
  	verdict = ((struct xt_standard_target *)t)->verdict;
  	verdict = -verdict - 1;
  	return verdict == NF_DROP || verdict == NF_ACCEPT;
  }
  
  static inline int check_entry_size_and_hooks(struct arpt_entry *e,
  					     struct xt_table_info *newinfo,
  					     const unsigned char *base,
  					     const unsigned char *limit,
  					     const unsigned int *hook_entries,
  					     const unsigned int *underflows,
  					     unsigned int valid_hooks)
  {
  	unsigned int h;
  	int err;
  
  	if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
  	    (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
  	    (unsigned char *)e + e->next_offset > limit)
  		return -EINVAL;
  
  	if (e->next_offset
  	    < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target))
  		return -EINVAL;
  
  	if (!arp_checkentry(&e->arp))
  		return -EINVAL;
  
  	err = xt_check_entry_offsets(e, e->elems, e->target_offset,
  				     e->next_offset);
  	if (err)
  		return err;
  
  	/* Check hooks & underflows */
  	for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
  		if (!(valid_hooks & (1 << h)))
  			continue;
  		if ((unsigned char *)e - base == hook_entries[h])
  			newinfo->hook_entry[h] = hook_entries[h];
  		if ((unsigned char *)e - base == underflows[h]) {
  			if (!check_underflow(e))
  				return -EINVAL;
  
  			newinfo->underflow[h] = underflows[h];
  		}
  	}
  
  	/* Clear counters and comefrom */
  	e->counters = ((struct xt_counters) { 0, 0 });
  	e->comefrom = 0;
  	return 0;
  }
  
  static inline void cleanup_entry(struct arpt_entry *e)
  {
  	struct xt_tgdtor_param par;
  	struct xt_entry_target *t;
  
  	t = arpt_get_target(e);
  	par.target   = t->u.kernel.target;
  	par.targinfo = t->data;
  	par.family   = NFPROTO_ARP;
  	if (par.target->destroy != NULL)
  		par.target->destroy(&par);
  	module_put(par.target->me);
  	xt_percpu_counter_free(&e->counters);
  }
  
  /* Checks and translates the user-supplied table segment (held in
   * newinfo).
   */
  static int translate_table(struct xt_table_info *newinfo, void *entry0,
  			   const struct arpt_replace *repl)
  {
  	struct xt_percpu_counter_alloc_state alloc_state = { 0 };
  	struct arpt_entry *iter;
  	unsigned int *offsets;
  	unsigned int i;
  	int ret = 0;
  
  	newinfo->size = repl->size;
  	newinfo->number = repl->num_entries;
  
  	/* Init all hooks to impossible value. */
  	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
  		newinfo->hook_entry[i] = 0xFFFFFFFF;
  		newinfo->underflow[i] = 0xFFFFFFFF;
  	}
  
  	offsets = xt_alloc_entry_offsets(newinfo->number);
  	if (!offsets)
  		return -ENOMEM;
  	i = 0;
  
  	/* Walk through entries, checking offsets. */
  	xt_entry_foreach(iter, entry0, newinfo->size) {
  		ret = check_entry_size_and_hooks(iter, newinfo, entry0,
  						 entry0 + repl->size,
  						 repl->hook_entry,
  						 repl->underflow,
  						 repl->valid_hooks);
  		if (ret != 0)
  			goto out_free;
  		if (i < repl->num_entries)
  			offsets[i] = (void *)iter - entry0;
  		++i;
  		if (strcmp(arpt_get_target(iter)->u.user.name,
  		    XT_ERROR_TARGET) == 0)
  			++newinfo->stacksize;
  	}
  
  	ret = -EINVAL;
  	if (i != repl->num_entries)
  		goto out_free;
  
  	/* Check hooks all assigned */
  	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
  		/* Only hooks which are valid */
  		if (!(repl->valid_hooks & (1 << i)))
  			continue;
  		if (newinfo->hook_entry[i] == 0xFFFFFFFF)
  			goto out_free;
  		if (newinfo->underflow[i] == 0xFFFFFFFF)
  			goto out_free;
  	}
  
  	if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) {
  		ret = -ELOOP;
  		goto out_free;
  	}
  	kvfree(offsets);
  
  	/* Finally, each sanity check must pass */
  	i = 0;
  	xt_entry_foreach(iter, entry0, newinfo->size) {
  		ret = find_check_entry(iter, repl->name, repl->size,
  				       &alloc_state);
  		if (ret != 0)
  			break;
  		++i;
  	}
  
  	if (ret != 0) {
  		xt_entry_foreach(iter, entry0, newinfo->size) {
  			if (i-- == 0)
  				break;
  			cleanup_entry(iter);
  		}
  		return ret;
  	}
  
  	return ret;
   out_free:
  	kvfree(offsets);
  	return ret;
  }
  
  static void get_counters(const struct xt_table_info *t,
  			 struct xt_counters counters[])
  {
  	struct arpt_entry *iter;
  	unsigned int cpu;
  	unsigned int i;
  
  	for_each_possible_cpu(cpu) {
  		seqcount_t *s = &per_cpu(xt_recseq, cpu);
  
  		i = 0;
  		xt_entry_foreach(iter, t->entries, t->size) {
  			struct xt_counters *tmp;
  			u64 bcnt, pcnt;
  			unsigned int start;
  
  			tmp = xt_get_per_cpu_counter(&iter->counters, cpu);
  			do {
  				start = read_seqcount_begin(s);
  				bcnt = tmp->bcnt;
  				pcnt = tmp->pcnt;
  			} while (read_seqcount_retry(s, start));
  
  			ADD_COUNTER(counters[i], bcnt, pcnt);
  			++i;
  			cond_resched();
  		}
  	}
  }
  
  static struct xt_counters *alloc_counters(const struct xt_table *table)
  {
  	unsigned int countersize;
  	struct xt_counters *counters;
  	const struct xt_table_info *private = table->private;
  
  	/* We need atomic snapshot of counters: rest doesn't change
  	 * (other than comefrom, which userspace doesn't care
  	 * about).
  	 */
  	countersize = sizeof(struct xt_counters) * private->number;
  	counters = vzalloc(countersize);
  
  	if (counters == NULL)
  		return ERR_PTR(-ENOMEM);
  
  	get_counters(private, counters);
  
  	return counters;
  }
  
  static int copy_entries_to_user(unsigned int total_size,
  				const struct xt_table *table,
  				void __user *userptr)
  {
  	unsigned int off, num;
  	const struct arpt_entry *e;
  	struct xt_counters *counters;
  	struct xt_table_info *private = table->private;
  	int ret = 0;
  	void *loc_cpu_entry;
  
  	counters = alloc_counters(table);
  	if (IS_ERR(counters))
  		return PTR_ERR(counters);
  
  	loc_cpu_entry = private->entries;
  
  	/* FIXME: use iterator macros --RR */
  	/* ... then go back and fix counters and names */
  	for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
  		const struct xt_entry_target *t;
  
  		e = loc_cpu_entry + off;
  		if (copy_to_user(userptr + off, e, sizeof(*e))) {
  			ret = -EFAULT;
  			goto free_counters;
  		}
  		if (copy_to_user(userptr + off
  				 + offsetof(struct arpt_entry, counters),
  				 &counters[num],
  				 sizeof(counters[num])) != 0) {
  			ret = -EFAULT;
  			goto free_counters;
  		}
  
  		t = arpt_get_target_c(e);
  		if (xt_target_to_user(t, userptr + off + e->target_offset)) {
  			ret = -EFAULT;
  			goto free_counters;
  		}
  	}
  
   free_counters:
  	vfree(counters);
  	return ret;
  }
  
  #ifdef CONFIG_COMPAT
  static void compat_standard_from_user(void *dst, const void *src)
  {
  	int v = *(compat_int_t *)src;
  
  	if (v > 0)
  		v += xt_compat_calc_jump(NFPROTO_ARP, v);
  	memcpy(dst, &v, sizeof(v));
  }
  
  static int compat_standard_to_user(void __user *dst, const void *src)
  {
  	compat_int_t cv = *(int *)src;
  
  	if (cv > 0)
  		cv -= xt_compat_calc_jump(NFPROTO_ARP, cv);
  	return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
  }
  
  static int compat_calc_entry(const struct arpt_entry *e,
  			     const struct xt_table_info *info,
  			     const void *base, struct xt_table_info *newinfo)
  {
  	const struct xt_entry_target *t;
  	unsigned int entry_offset;
  	int off, i, ret;
  
  	off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
  	entry_offset = (void *)e - base;
  
  	t = arpt_get_target_c(e);
  	off += xt_compat_target_offset(t->u.kernel.target);
  	newinfo->size -= off;
  	ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
  	if (ret)
  		return ret;
  
  	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
  		if (info->hook_entry[i] &&
  		    (e < (struct arpt_entry *)(base + info->hook_entry[i])))
  			newinfo->hook_entry[i] -= off;
  		if (info->underflow[i] &&
  		    (e < (struct arpt_entry *)(base + info->underflow[i])))
  			newinfo->underflow[i] -= off;
  	}
  	return 0;
  }
  
  static int compat_table_info(const struct xt_table_info *info,
  			     struct xt_table_info *newinfo)
  {
  	struct arpt_entry *iter;
  	const void *loc_cpu_entry;
  	int ret;
  
  	if (!newinfo || !info)
  		return -EINVAL;
  
  	/* we dont care about newinfo->entries */
  	memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
  	newinfo->initial_entries = 0;
  	loc_cpu_entry = info->entries;
  	ret = xt_compat_init_offsets(NFPROTO_ARP, info->number);
  	if (ret)
  		return ret;
  	xt_entry_foreach(iter, loc_cpu_entry, info->size) {
  		ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
  		if (ret != 0)
  			return ret;
  	}
  	return 0;
  }
  #endif
  
  static int get_info(struct net *net, void __user *user,
  		    const int *len, int compat)
  {
  	char name[XT_TABLE_MAXNAMELEN];
  	struct xt_table *t;
  	int ret;
  
  	if (*len != sizeof(struct arpt_getinfo))
  		return -EINVAL;
  
  	if (copy_from_user(name, user, sizeof(name)) != 0)
  		return -EFAULT;
  
  	name[XT_TABLE_MAXNAMELEN-1] = '\0';
  #ifdef CONFIG_COMPAT
  	if (compat)
  		xt_compat_lock(NFPROTO_ARP);
  #endif
  	t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
  				    "arptable_%s", name);
  	if (t) {
  		struct arpt_getinfo info;
  		const struct xt_table_info *private = t->private;
  #ifdef CONFIG_COMPAT
  		struct xt_table_info tmp;
  
  		if (compat) {
  			ret = compat_table_info(private, &tmp);
  			xt_compat_flush_offsets(NFPROTO_ARP);
  			private = &tmp;
  		}
  #endif
  		memset(&info, 0, sizeof(info));
  		info.valid_hooks = t->valid_hooks;
  		memcpy(info.hook_entry, private->hook_entry,
  		       sizeof(info.hook_entry));
  		memcpy(info.underflow, private->underflow,
  		       sizeof(info.underflow));
  		info.num_entries = private->number;
  		info.size = private->size;
  		strcpy(info.name, name);
  
  		if (copy_to_user(user, &info, *len) != 0)
  			ret = -EFAULT;
  		else
  			ret = 0;
  		xt_table_unlock(t);
  		module_put(t->me);
  	} else
  		ret = -ENOENT;
  #ifdef CONFIG_COMPAT
  	if (compat)
  		xt_compat_unlock(NFPROTO_ARP);
  #endif
  	return ret;
  }
  
  static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
  		       const int *len)
  {
  	int ret;
  	struct arpt_get_entries get;
  	struct xt_table *t;
  
  	if (*len < sizeof(get))
  		return -EINVAL;
  	if (copy_from_user(&get, uptr, sizeof(get)) != 0)
  		return -EFAULT;
  	if (*len != sizeof(struct arpt_get_entries) + get.size)
  		return -EINVAL;
  
  	get.name[sizeof(get.name) - 1] = '\0';
  
  	t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
  	if (t) {
  		const struct xt_table_info *private = t->private;
  
  		if (get.size == private->size)
  			ret = copy_entries_to_user(private->size,
  						   t, uptr->entrytable);
  		else
  			ret = -EAGAIN;
  
  		module_put(t->me);
  		xt_table_unlock(t);
  	} else
  		ret = -ENOENT;
  
  	return ret;
  }
  
  static int __do_replace(struct net *net, const char *name,
  			unsigned int valid_hooks,
  			struct xt_table_info *newinfo,
  			unsigned int num_counters,
  			void __user *counters_ptr)
  {
  	int ret;
  	struct xt_table *t;
  	struct xt_table_info *oldinfo;
  	struct xt_counters *counters;
  	void *loc_cpu_old_entry;
  	struct arpt_entry *iter;
  
  	ret = 0;
  	counters = xt_counters_alloc(num_counters);
  	if (!counters) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
  				    "arptable_%s", name);
  	if (!t) {
  		ret = -ENOENT;
  		goto free_newinfo_counters_untrans;
  	}
  
  	/* You lied! */
  	if (valid_hooks != t->valid_hooks) {
  		ret = -EINVAL;
  		goto put_module;
  	}
  
  	oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
  	if (!oldinfo)
  		goto put_module;
  
  	/* Update module usage count based on number of rules */
  	if ((oldinfo->number > oldinfo->initial_entries) ||
  	    (newinfo->number <= oldinfo->initial_entries))
  		module_put(t->me);
  	if ((oldinfo->number > oldinfo->initial_entries) &&
  	    (newinfo->number <= oldinfo->initial_entries))
  		module_put(t->me);
  
  	/* Get the old counters, and synchronize with replace */
  	get_counters(oldinfo, counters);
  
  	/* Decrease module usage counts and free resource */
  	loc_cpu_old_entry = oldinfo->entries;
  	xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
  		cleanup_entry(iter);
  
  	xt_free_table_info(oldinfo);
  	if (copy_to_user(counters_ptr, counters,
  			 sizeof(struct xt_counters) * num_counters) != 0) {
  		/* Silent error, can't fail, new table is already in place */
  		net_warn_ratelimited("arptables: counters copy to user failed while replacing table\n");
  	}
  	vfree(counters);
  	xt_table_unlock(t);
  	return ret;
  
   put_module:
  	module_put(t->me);
  	xt_table_unlock(t);
   free_newinfo_counters_untrans:
  	vfree(counters);
   out:
  	return ret;
  }
  
  static int do_replace(struct net *net, const void __user *user,
  		      unsigned int len)
  {
  	int ret;
  	struct arpt_replace tmp;
  	struct xt_table_info *newinfo;
  	void *loc_cpu_entry;
  	struct arpt_entry *iter;
  
  	if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
  		return -EFAULT;
  
  	/* overflow check */
  	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
  		return -ENOMEM;
  	if (tmp.num_counters == 0)
  		return -EINVAL;
  
  	tmp.name[sizeof(tmp.name)-1] = 0;
  
  	newinfo = xt_alloc_table_info(tmp.size);
  	if (!newinfo)
  		return -ENOMEM;
  
  	loc_cpu_entry = newinfo->entries;
  	if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
  			   tmp.size) != 0) {
  		ret = -EFAULT;
  		goto free_newinfo;
  	}
  
  	ret = translate_table(newinfo, loc_cpu_entry, &tmp);
  	if (ret != 0)
  		goto free_newinfo;
  
  	ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
  			   tmp.num_counters, tmp.counters);
  	if (ret)
  		goto free_newinfo_untrans;
  	return 0;
  
   free_newinfo_untrans:
  	xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
  		cleanup_entry(iter);
   free_newinfo:
  	xt_free_table_info(newinfo);
  	return ret;
  }
  
  static int do_add_counters(struct net *net, const void __user *user,
  			   unsigned int len, int compat)
  {
  	unsigned int i;
  	struct xt_counters_info tmp;
  	struct xt_counters *paddc;
  	struct xt_table *t;
  	const struct xt_table_info *private;
  	int ret = 0;
  	struct arpt_entry *iter;
  	unsigned int addend;
  
  	paddc = xt_copy_counters_from_user(user, len, &tmp, compat);
  	if (IS_ERR(paddc))
  		return PTR_ERR(paddc);
  
  	t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
  	if (!t) {
  		ret = -ENOENT;
  		goto free;
  	}
  
  	local_bh_disable();
  	private = t->private;
  	if (private->number != tmp.num_counters) {
  		ret = -EINVAL;
  		goto unlock_up_free;
  	}
  
  	i = 0;
  
  	addend = xt_write_recseq_begin();
  	xt_entry_foreach(iter,  private->entries, private->size) {
  		struct xt_counters *tmp;
  
  		tmp = xt_get_this_cpu_counter(&iter->counters);
  		ADD_COUNTER(*tmp, paddc[i].bcnt, paddc[i].pcnt);
  		++i;
  	}
  	xt_write_recseq_end(addend);
   unlock_up_free:
  	local_bh_enable();
  	xt_table_unlock(t);
  	module_put(t->me);
   free:
  	vfree(paddc);
  
  	return ret;
  }
  
  #ifdef CONFIG_COMPAT
  struct compat_arpt_replace {
  	char				name[XT_TABLE_MAXNAMELEN];
  	u32				valid_hooks;
  	u32				num_entries;
  	u32				size;
  	u32				hook_entry[NF_ARP_NUMHOOKS];
  	u32				underflow[NF_ARP_NUMHOOKS];
  	u32				num_counters;
  	compat_uptr_t			counters;
  	struct compat_arpt_entry	entries[0];
  };
  
  static inline void compat_release_entry(struct compat_arpt_entry *e)
  {
  	struct xt_entry_target *t;
  
  	t = compat_arpt_get_target(e);
  	module_put(t->u.kernel.target->me);
  }
  
  static int
  check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
  				  struct xt_table_info *newinfo,
  				  unsigned int *size,
  				  const unsigned char *base,
  				  const unsigned char *limit)
  {
  	struct xt_entry_target *t;
  	struct xt_target *target;
  	unsigned int entry_offset;
  	int ret, off;
  
  	if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
  	    (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
  	    (unsigned char *)e + e->next_offset > limit)
  		return -EINVAL;
  
  	if (e->next_offset < sizeof(struct compat_arpt_entry) +
  			     sizeof(struct compat_xt_entry_target))
  		return -EINVAL;
  
  	if (!arp_checkentry(&e->arp))
  		return -EINVAL;
  
  	ret = xt_compat_check_entry_offsets(e, e->elems, e->target_offset,
  					    e->next_offset);
  	if (ret)
  		return ret;
  
  	off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
  	entry_offset = (void *)e - (void *)base;
  
  	t = compat_arpt_get_target(e);
  	target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
  					t->u.user.revision);
  	if (IS_ERR(target)) {
  		ret = PTR_ERR(target);
  		goto out;
  	}
  	t->u.kernel.target = target;
  
  	off += xt_compat_target_offset(target);
  	*size += off;
  	ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
  	if (ret)
  		goto release_target;
  
  	return 0;
  
  release_target:
  	module_put(t->u.kernel.target->me);
  out:
  	return ret;
  }
  
  static void
  compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
  			    unsigned int *size,
  			    struct xt_table_info *newinfo, unsigned char *base)
  {
  	struct xt_entry_target *t;
  	struct arpt_entry *de;
  	unsigned int origsize;
  	int h;
  
  	origsize = *size;
  	de = *dstptr;
  	memcpy(de, e, sizeof(struct arpt_entry));
  	memcpy(&de->counters, &e->counters, sizeof(e->counters));
  
  	*dstptr += sizeof(struct arpt_entry);
  	*size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
  
  	de->target_offset = e->target_offset - (origsize - *size);
  	t = compat_arpt_get_target(e);
  	xt_compat_target_from_user(t, dstptr, size);
  
  	de->next_offset = e->next_offset - (origsize - *size);
  	for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
  		if ((unsigned char *)de - base < newinfo->hook_entry[h])
  			newinfo->hook_entry[h] -= origsize - *size;
  		if ((unsigned char *)de - base < newinfo->underflow[h])
  			newinfo->underflow[h] -= origsize - *size;
  	}
  }
  
  static int translate_compat_table(struct xt_table_info **pinfo,
  				  void **pentry0,
  				  const struct compat_arpt_replace *compatr)
  {
  	unsigned int i, j;
  	struct xt_table_info *newinfo, *info;
  	void *pos, *entry0, *entry1;
  	struct compat_arpt_entry *iter0;
  	struct arpt_replace repl;
  	unsigned int size;
  	int ret;
  
  	info = *pinfo;
  	entry0 = *pentry0;
  	size = compatr->size;
  	info->number = compatr->num_entries;
  
  	j = 0;
  	xt_compat_lock(NFPROTO_ARP);
  	ret = xt_compat_init_offsets(NFPROTO_ARP, compatr->num_entries);
  	if (ret)
  		goto out_unlock;
  	/* Walk through entries, checking offsets. */
  	xt_entry_foreach(iter0, entry0, compatr->size) {
  		ret = check_compat_entry_size_and_hooks(iter0, info, &size,
  							entry0,
  							entry0 + compatr->size);
  		if (ret != 0)
  			goto out_unlock;
  		++j;
  	}
  
  	ret = -EINVAL;
  	if (j != compatr->num_entries)
  		goto out_unlock;
  
  	ret = -ENOMEM;
  	newinfo = xt_alloc_table_info(size);
  	if (!newinfo)
  		goto out_unlock;
  
  	newinfo->number = compatr->num_entries;
  	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
  		newinfo->hook_entry[i] = compatr->hook_entry[i];
  		newinfo->underflow[i] = compatr->underflow[i];
  	}
  	entry1 = newinfo->entries;
  	pos = entry1;
  	size = compatr->size;
  	xt_entry_foreach(iter0, entry0, compatr->size)
  		compat_copy_entry_from_user(iter0, &pos, &size,
  					    newinfo, entry1);
  
  	/* all module references in entry0 are now gone */
  
  	xt_compat_flush_offsets(NFPROTO_ARP);
  	xt_compat_unlock(NFPROTO_ARP);
  
  	memcpy(&repl, compatr, sizeof(*compatr));
  
  	for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
  		repl.hook_entry[i] = newinfo->hook_entry[i];
  		repl.underflow[i] = newinfo->underflow[i];
  	}
  
  	repl.num_counters = 0;
  	repl.counters = NULL;
  	repl.size = newinfo->size;
  	ret = translate_table(newinfo, entry1, &repl);
  	if (ret)
  		goto free_newinfo;
  
  	*pinfo = newinfo;
  	*pentry0 = entry1;
  	xt_free_table_info(info);
  	return 0;
  
  free_newinfo:
  	xt_free_table_info(newinfo);
  	return ret;
  out_unlock:
  	xt_compat_flush_offsets(NFPROTO_ARP);
  	xt_compat_unlock(NFPROTO_ARP);
  	xt_entry_foreach(iter0, entry0, compatr->size) {
  		if (j-- == 0)
  			break;
  		compat_release_entry(iter0);
  	}
  	return ret;
  }
  
  static int compat_do_replace(struct net *net, void __user *user,
  			     unsigned int len)
  {
  	int ret;
  	struct compat_arpt_replace tmp;
  	struct xt_table_info *newinfo;
  	void *loc_cpu_entry;
  	struct arpt_entry *iter;
  
  	if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
  		return -EFAULT;
  
  	/* overflow check */
  	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
  		return -ENOMEM;
  	if (tmp.num_counters == 0)
  		return -EINVAL;
  
  	tmp.name[sizeof(tmp.name)-1] = 0;
  
  	newinfo = xt_alloc_table_info(tmp.size);
  	if (!newinfo)
  		return -ENOMEM;
  
  	loc_cpu_entry = newinfo->entries;
  	if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
  		ret = -EFAULT;
  		goto free_newinfo;
  	}
  
  	ret = translate_compat_table(&newinfo, &loc_cpu_entry, &tmp);
  	if (ret != 0)
  		goto free_newinfo;
  
  	ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
  			   tmp.num_counters, compat_ptr(tmp.counters));
  	if (ret)
  		goto free_newinfo_untrans;
  	return 0;
  
   free_newinfo_untrans:
  	xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
  		cleanup_entry(iter);
   free_newinfo:
  	xt_free_table_info(newinfo);
  	return ret;
  }
  
  static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
  				  unsigned int len)
  {
  	int ret;
  
  	if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
  		return -EPERM;
  
  	switch (cmd) {
  	case ARPT_SO_SET_REPLACE:
  		ret = compat_do_replace(sock_net(sk), user, len);
  		break;
  
  	case ARPT_SO_SET_ADD_COUNTERS:
  		ret = do_add_counters(sock_net(sk), user, len, 1);
  		break;
  
  	default:
  		ret = -EINVAL;
  	}
  
  	return ret;
  }
  
  static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
  				     compat_uint_t *size,
  				     struct xt_counters *counters,
  				     unsigned int i)
  {
  	struct xt_entry_target *t;
  	struct compat_arpt_entry __user *ce;
  	u_int16_t target_offset, next_offset;
  	compat_uint_t origsize;
  	int ret;
  
  	origsize = *size;
  	ce = *dstptr;
  	if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
  	    copy_to_user(&ce->counters, &counters[i],
  	    sizeof(counters[i])) != 0)
  		return -EFAULT;
  
  	*dstptr += sizeof(struct compat_arpt_entry);
  	*size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
  
  	target_offset = e->target_offset - (origsize - *size);
  
  	t = arpt_get_target(e);
  	ret = xt_compat_target_to_user(t, dstptr, size);
  	if (ret)
  		return ret;
  	next_offset = e->next_offset - (origsize - *size);
  	if (put_user(target_offset, &ce->target_offset) != 0 ||
  	    put_user(next_offset, &ce->next_offset) != 0)
  		return -EFAULT;
  	return 0;
  }
  
  static int compat_copy_entries_to_user(unsigned int total_size,
  				       struct xt_table *table,
  				       void __user *userptr)
  {
  	struct xt_counters *counters;
  	const struct xt_table_info *private = table->private;
  	void __user *pos;
  	unsigned int size;
  	int ret = 0;
  	unsigned int i = 0;
  	struct arpt_entry *iter;
  
  	counters = alloc_counters(table);
  	if (IS_ERR(counters))
  		return PTR_ERR(counters);
  
  	pos = userptr;
  	size = total_size;
  	xt_entry_foreach(iter, private->entries, total_size) {
  		ret = compat_copy_entry_to_user(iter, &pos,
  						&size, counters, i++);
  		if (ret != 0)
  			break;
  	}
  	vfree(counters);
  	return ret;
  }
  
  struct compat_arpt_get_entries {
  	char name[XT_TABLE_MAXNAMELEN];
  	compat_uint_t size;
  	struct compat_arpt_entry entrytable[0];
  };
  
  static int compat_get_entries(struct net *net,
  			      struct compat_arpt_get_entries __user *uptr,
  			      int *len)
  {
  	int ret;
  	struct compat_arpt_get_entries get;
  	struct xt_table *t;
  
  	if (*len < sizeof(get))
  		return -EINVAL;
  	if (copy_from_user(&get, uptr, sizeof(get)) != 0)
  		return -EFAULT;
  	if (*len != sizeof(struct compat_arpt_get_entries) + get.size)
  		return -EINVAL;
  
  	get.name[sizeof(get.name) - 1] = '\0';
  
  	xt_compat_lock(NFPROTO_ARP);
  	t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
  	if (t) {
  		const struct xt_table_info *private = t->private;
  		struct xt_table_info info;
  
  		ret = compat_table_info(private, &info);
  		if (!ret && get.size == info.size) {
  			ret = compat_copy_entries_to_user(private->size,
  							  t, uptr->entrytable);
  		} else if (!ret)
  			ret = -EAGAIN;
  
  		xt_compat_flush_offsets(NFPROTO_ARP);
  		module_put(t->me);
  		xt_table_unlock(t);
  	} else
  		ret = -ENOENT;
  
  	xt_compat_unlock(NFPROTO_ARP);
  	return ret;
  }
  
  static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);
  
  static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
  				  int *len)
  {
  	int ret;
  
  	if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
  		return -EPERM;
  
  	switch (cmd) {
  	case ARPT_SO_GET_INFO:
  		ret = get_info(sock_net(sk), user, len, 1);
  		break;
  	case ARPT_SO_GET_ENTRIES:
  		ret = compat_get_entries(sock_net(sk), user, len);
  		break;
  	default:
  		ret = do_arpt_get_ctl(sk, cmd, user, len);
  	}
  	return ret;
  }
  #endif
  
  static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
  {
  	int ret;
  
  	if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
  		return -EPERM;
  
  	switch (cmd) {
  	case ARPT_SO_SET_REPLACE:
  		ret = do_replace(sock_net(sk), user, len);
  		break;
  
  	case ARPT_SO_SET_ADD_COUNTERS:
  		ret = do_add_counters(sock_net(sk), user, len, 0);
  		break;
  
  	default:
  		ret = -EINVAL;
  	}
  
  	return ret;
  }
  
  static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
  {
  	int ret;
  
  	if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
  		return -EPERM;
  
  	switch (cmd) {
  	case ARPT_SO_GET_INFO:
  		ret = get_info(sock_net(sk), user, len, 0);
  		break;
  
  	case ARPT_SO_GET_ENTRIES:
  		ret = get_entries(sock_net(sk), user, len);
  		break;
  
  	case ARPT_SO_GET_REVISION_TARGET: {
  		struct xt_get_revision rev;
  
  		if (*len != sizeof(rev)) {
  			ret = -EINVAL;
  			break;
  		}
  		if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
  			ret = -EFAULT;
  			break;
  		}
  		rev.name[sizeof(rev.name)-1] = 0;
  
  		try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
  							 rev.revision, 1, &ret),
  					"arpt_%s", rev.name);
  		break;
  	}
  
  	default:
  		ret = -EINVAL;
  	}
  
  	return ret;
  }
  
  static void __arpt_unregister_table(struct xt_table *table)
  {
  	struct xt_table_info *private;
  	void *loc_cpu_entry;
  	struct module *table_owner = table->me;
  	struct arpt_entry *iter;
  
  	private = xt_unregister_table(table);
  
  	/* Decrease module usage counts and free resources */
  	loc_cpu_entry = private->entries;
  	xt_entry_foreach(iter, loc_cpu_entry, private->size)
  		cleanup_entry(iter);
  	if (private->number > private->initial_entries)
  		module_put(table_owner);
  	xt_free_table_info(private);
  }
  
  int arpt_register_table(struct net *net,
  			const struct xt_table *table,
  			const struct arpt_replace *repl,
  			const struct nf_hook_ops *ops,
  			struct xt_table **res)
  {
  	int ret;
  	struct xt_table_info *newinfo;
  	struct xt_table_info bootstrap = {0};
  	void *loc_cpu_entry;
  	struct xt_table *new_table;
  
  	newinfo = xt_alloc_table_info(repl->size);
  	if (!newinfo)
  		return -ENOMEM;
  
  	loc_cpu_entry = newinfo->entries;
  	memcpy(loc_cpu_entry, repl->entries, repl->size);
  
  	ret = translate_table(newinfo, loc_cpu_entry, repl);
  	if (ret != 0)
  		goto out_free;
  
  	new_table = xt_register_table(net, table, &bootstrap, newinfo);
  	if (IS_ERR(new_table)) {
  		ret = PTR_ERR(new_table);
  		goto out_free;
  	}
  
  	/* set res now, will see skbs right after nf_register_net_hooks */
  	WRITE_ONCE(*res, new_table);
  
  	ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
  	if (ret != 0) {
  		__arpt_unregister_table(new_table);
  		*res = NULL;
  	}
  
  	return ret;
  
  out_free:
  	xt_free_table_info(newinfo);
  	return ret;
  }
  
  void arpt_unregister_table(struct net *net, struct xt_table *table,
  			   const struct nf_hook_ops *ops)
  {
  	nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
  	__arpt_unregister_table(table);
  }
  
  /* The built-in targets: standard (NULL) and error. */
  static struct xt_target arpt_builtin_tg[] __read_mostly = {
  	{
  		.name             = XT_STANDARD_TARGET,
  		.targetsize       = sizeof(int),
  		.family           = NFPROTO_ARP,
  #ifdef CONFIG_COMPAT
  		.compatsize       = sizeof(compat_int_t),
  		.compat_from_user = compat_standard_from_user,
  		.compat_to_user   = compat_standard_to_user,
  #endif
  	},
  	{
  		.name             = XT_ERROR_TARGET,
  		.target           = arpt_error,
  		.targetsize       = XT_FUNCTION_MAXNAMELEN,
  		.family           = NFPROTO_ARP,
  	},
  };
  
  static struct nf_sockopt_ops arpt_sockopts = {
  	.pf		= PF_INET,
  	.set_optmin	= ARPT_BASE_CTL,
  	.set_optmax	= ARPT_SO_SET_MAX+1,
  	.set		= do_arpt_set_ctl,
  #ifdef CONFIG_COMPAT
  	.compat_set	= compat_do_arpt_set_ctl,
  #endif
  	.get_optmin	= ARPT_BASE_CTL,
  	.get_optmax	= ARPT_SO_GET_MAX+1,
  	.get		= do_arpt_get_ctl,
  #ifdef CONFIG_COMPAT
  	.compat_get	= compat_do_arpt_get_ctl,
  #endif
  	.owner		= THIS_MODULE,
  };
  
  static int __net_init arp_tables_net_init(struct net *net)
  {
  	return xt_proto_init(net, NFPROTO_ARP);
  }
  
  static void __net_exit arp_tables_net_exit(struct net *net)
  {
  	xt_proto_fini(net, NFPROTO_ARP);
  }
  
  static struct pernet_operations arp_tables_net_ops = {
  	.init = arp_tables_net_init,
  	.exit = arp_tables_net_exit,
  };
  
  static int __init arp_tables_init(void)
  {
  	int ret;
  
  	ret = register_pernet_subsys(&arp_tables_net_ops);
  	if (ret < 0)
  		goto err1;
  
  	/* No one else will be downing sem now, so we won't sleep */
  	ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
  	if (ret < 0)
  		goto err2;
  
  	/* Register setsockopt */
  	ret = nf_register_sockopt(&arpt_sockopts);
  	if (ret < 0)
  		goto err4;
  
  	pr_info("arp_tables: (C) 2002 David S. Miller\n");
  	return 0;
  
  err4:
  	xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
  err2:
  	unregister_pernet_subsys(&arp_tables_net_ops);
  err1:
  	return ret;
  }
  
  static void __exit arp_tables_fini(void)
  {
  	nf_unregister_sockopt(&arpt_sockopts);
  	xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
  	unregister_pernet_subsys(&arp_tables_net_ops);
  }
  
  EXPORT_SYMBOL(arpt_register_table);
  EXPORT_SYMBOL(arpt_unregister_table);
  EXPORT_SYMBOL(arpt_do_table);
  
  module_init(arp_tables_init);
  module_exit(arp_tables_fini);
  