ebtables.c

/*
 *  ebtables
 *
 *  Author:
 *  Bart De Schuymer		<bdschuym@pandora.be>
 *
 *  ebtables.c,v 2.0, July, 2002
 *
 *  This code is stongly inspired on the iptables code which is
 *  Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
 *
 *  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.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <net/sock.h>
/* needed for logical [in,out]-dev filtering */
#include "../br_private.h"

#define BUGPRINT(format, args...) printk("kernel msg: ebtables bug: please "\
					 "report to author: "format, ## args)
/* #define BUGPRINT(format, args...) */

/*
 * Each cpu has its own set of counters, so there is no need for write_lock in
 * the softirq
 * For reading or updating the counters, the user context needs to
 * get a write_lock
 */

/* The size of each set of counters is altered to get cache alignment */
#define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
#define COUNTER_OFFSET(n) (SMP_ALIGN(n * sizeof(struct ebt_counter)))
#define COUNTER_BASE(c, n, cpu) ((struct ebt_counter *)(((char *)c) + \
   COUNTER_OFFSET(n) * cpu))



static DEFINE_MUTEX(ebt_mutex);

#ifdef CONFIG_COMPAT
static void ebt_standard_compat_from_user(void *dst, const void *src)
{
	int v = *(compat_int_t *)src;

	if (v >= 0)
		v += xt_compat_calc_jump(NFPROTO_BRIDGE, v);
	memcpy(dst, &v, sizeof(v));
}

static int ebt_standard_compat_to_user(void __user *dst, const void *src)
{
	compat_int_t cv = *(int *)src;

	if (cv >= 0)
		cv -= xt_compat_calc_jump(NFPROTO_BRIDGE, cv);
	return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
}
#endif


static struct xt_target ebt_standard_target = {
	.name       = "standard",
	.revision   = 0,
	.family     = NFPROTO_BRIDGE,
	.targetsize = sizeof(int),
#ifdef CONFIG_COMPAT
	.compatsize = sizeof(compat_int_t),
	.compat_from_user = ebt_standard_compat_from_user,
	.compat_to_user =  ebt_standard_compat_to_user,
#endif
};

static inline int
ebt_do_watcher(const struct ebt_entry_watcher *w, struct sk_buff *skb,
	       struct xt_action_param *par)
{
	par->target   = w->u.watcher;
	par->targinfo = w->data;
	w->u.watcher->target(skb, par);
	/* watchers don't give a verdict */
	return 0;
}

static inline int
ebt_do_match(struct ebt_entry_match *m, const struct sk_buff *skb,
	     struct xt_action_param *par)
{
	par->match     = m->u.match;
	par->matchinfo = m->data;
	return m->u.match->match(skb, par) ? EBT_MATCH : EBT_NOMATCH;
}

static inline int
ebt_dev_check(const char *entry, const struct net_device *device)
{
	int i = 0;
	const char *devname;

	if (*entry == '\0')
		return 0;
	if (!device)
		return 1;
	devname = device->name;
	/* 1 is the wildcard token */
	while (entry[i] != '\0' && entry[i] != 1 && entry[i] == devname[i])
		i++;
	return devname[i] != entry[i] && entry[i] != 1;
}

#define FWINV2(bool, invflg) ((bool) ^ !!(e->invflags & invflg))
/* process standard matches */
static inline int
ebt_basic_match(const struct ebt_entry *e, const struct sk_buff *skb,
                const struct net_device *in, const struct net_device *out)
{
	const struct ethhdr *h = eth_hdr(skb);
	const struct net_bridge_port *p;
	__be16 ethproto;
	int verdict, i;

	if (vlan_tx_tag_present(skb))
		ethproto = htons(ETH_P_8021Q);
	else
		ethproto = h->h_proto;

	if (e->bitmask & EBT_802_3) {
		if (FWINV2(ntohs(ethproto) >= ETH_P_802_3_MIN, EBT_IPROTO))
			return 1;
	} else if (!(e->bitmask & EBT_NOPROTO) &&
	   FWINV2(e->ethproto != ethproto, EBT_IPROTO))
		return 1;

	if (FWINV2(ebt_dev_check(e->in, in), EBT_IIN))
		return 1;
	if (FWINV2(ebt_dev_check(e->out, out), EBT_IOUT))
		return 1;
	/* rcu_read_lock()ed by nf_hook_slow */
	if (in && (p = br_port_get_rcu(in)) != NULL &&
	    FWINV2(ebt_dev_check(e->logical_in, p->br->dev), EBT_ILOGICALIN))
		return 1;
	if (out && (p = br_port_get_rcu(out)) != NULL &&
	    FWINV2(ebt_dev_check(e->logical_out, p->br->dev), EBT_ILOGICALOUT))
		return 1;

	if (e->bitmask & EBT_SOURCEMAC) {
		verdict = 0;
		for (i = 0; i < 6; i++)
			verdict |= (h->h_source[i] ^ e->sourcemac[i]) &
			   e->sourcemsk[i];
		if (FWINV2(verdict != 0, EBT_ISOURCE) )
			return 1;
	}
	if (e->bitmask & EBT_DESTMAC) {
		verdict = 0;
		for (i = 0; i < 6; i++)
			verdict |= (h->h_dest[i] ^ e->destmac[i]) &
			   e->destmsk[i];
		if (FWINV2(verdict != 0, EBT_IDEST) )
			return 1;
	}
	return 0;
}

static inline __pure
struct ebt_entry *ebt_next_entry(const struct ebt_entry *entry)
{
	return (void *)entry + entry->next_offset;
}

/* Do some firewalling */
unsigned int ebt_do_table (unsigned int hook, struct sk_buff *skb,
   const struct net_device *in, const struct net_device *out,
   struct ebt_table *table)
{
	int i, nentries;
	struct ebt_entry *point;
	struct ebt_counter *counter_base, *cb_base;
	const struct ebt_entry_target *t;
	int verdict, sp = 0;
	struct ebt_chainstack *cs;
	struct ebt_entries *chaininfo;
	const char *base;
	const struct ebt_table_info *private;
	struct xt_action_param acpar;

	acpar.family  = NFPROTO_BRIDGE;
	acpar.in      = in;
	acpar.out     = out;
	acpar.hotdrop = false;
	acpar.hooknum = hook;

	read_lock_bh(&table->lock);
	private = table->private;
	cb_base = COUNTER_BASE(private->counters, private->nentries,
	   smp_processor_id());
	if (private->chainstack)
		cs = private->chainstack[smp_processor_id()];
	else
		cs = NULL;
	chaininfo = private->hook_entry[hook];
	nentries = private->hook_entry[hook]->nentries;
	point = (struct ebt_entry *)(private->hook_entry[hook]->data);
	counter_base = cb_base + private->hook_entry[hook]->counter_offset;
	/* base for chain jumps */
	base = private->entries;
	i = 0;
	while (i < nentries) {
		if (ebt_basic_match(point, skb, in, out))
			goto letscontinue;

		if (EBT_MATCH_ITERATE(point, ebt_do_match, skb, &acpar) != 0)
			goto letscontinue;
		if (acpar.hotdrop) {
			read_unlock_bh(&table->lock);
			return NF_DROP;
		}

		/* increase counter */
		(*(counter_base + i)).pcnt++;
		(*(counter_base + i)).bcnt += skb->len;

		/* these should only watch: not modify, nor tell us
		   what to do with the packet */
		EBT_WATCHER_ITERATE(point, ebt_do_watcher, skb, &acpar);

		t = (struct ebt_entry_target *)
		   (((char *)point) + point->target_offset);
		/* standard target */
		if (!t->u.target->target)
			verdict = ((struct ebt_standard_target *)t)->verdict;
		else {
			acpar.target   = t->u.target;
			acpar.targinfo = t->data;
			verdict = t->u.target->target(skb, &acpar);
		}
		if (verdict == EBT_ACCEPT) {
			read_unlock_bh(&table->lock);
			return NF_ACCEPT;
		}
		if (verdict == EBT_DROP) {
			read_unlock_bh(&table->lock);
			return NF_DROP;
		}
		if (verdict == EBT_RETURN) {
letsreturn:
#ifdef CONFIG_NETFILTER_DEBUG
			if (sp == 0) {
				BUGPRINT("RETURN on base chain");
				/* act like this is EBT_CONTINUE */
				goto letscontinue;
			}
#endif
			sp--;
			/* put all the local variables right */
			i = cs[sp].n;
			chaininfo = cs[sp].chaininfo;
			nentries = chaininfo->nentries;
			point = cs[sp].e;
			counter_base = cb_base +
			   chaininfo->counter_offset;
			continue;
		}
		if (verdict == EBT_CONTINUE)
			goto letscontinue;
#ifdef CONFIG_NETFILTER_DEBUG
		if (verdict < 0) {
			BUGPRINT("bogus standard verdict\n");
			read_unlock_bh(&table->lock);
			return NF_DROP;
		}
#endif
		/* jump to a udc */
		cs[sp].n = i + 1;
		cs[sp].chaininfo = chaininfo;
		cs[sp].e = ebt_next_entry(point);
		i = 0;
		chaininfo = (struct ebt_entries *) (base + verdict);
#ifdef CONFIG_NETFILTER_DEBUG
		if (chaininfo->distinguisher) {
			BUGPRINT("jump to non-chain\n");
			read_unlock_bh(&table->lock);
			return NF_DROP;
		}
#endif
		nentries = chaininfo->nentries;
		point = (struct ebt_entry *)chaininfo->data;
		counter_base = cb_base + chaininfo->counter_offset;
		sp++;
		continue;
letscontinue:
		point = ebt_next_entry(point);
		i++;
	}

	/* I actually like this :) */
	if (chaininfo->policy == EBT_RETURN)
		goto letsreturn;
	if (chaininfo->policy == EBT_ACCEPT) {
		read_unlock_bh(&table->lock);
		return NF_ACCEPT;
	}
	read_unlock_bh(&table->lock);
	return NF_DROP;
}

/* If it succeeds, returns element and locks mutex */
static inline void *
find_inlist_lock_noload(struct list_head *head, const char *name, int *error,
   struct mutex *mutex)
{
	struct {
		struct list_head list;
		char name[EBT_FUNCTION_MAXNAMELEN];
	} *e;

	mutex_lock(mutex);
	list_for_each_entry(e, head, list) {
		if (strcmp(e->name, name) == 0)
			return e;
	}
	*error = -ENOENT;
	mutex_unlock(mutex);
	return NULL;
}

static void *
find_inlist_lock(struct list_head *head, const char *name, const char *prefix,
   int *error, struct mutex *mutex)
{
	return try_then_request_module(
			find_inlist_lock_noload(head, name, error, mutex),
			"%s%s", prefix, name);
}

static inline struct ebt_table *
find_table_lock(struct net *net, const char *name, int *error,
		struct mutex *mutex)
{
	return find_inlist_lock(&net->xt.tables[NFPROTO_BRIDGE], name,
				"ebtable_", error, mutex);
}

static inline int
ebt_check_match(struct ebt_entry_match *m, struct xt_mtchk_param *par,
		unsigned int *cnt)
{
	const struct ebt_entry *e = par->entryinfo;
	struct xt_match *match;
	size_t left = ((char *)e + e->watchers_offset) - (char *)m;
	int ret;

	if (left < sizeof(struct ebt_entry_match) ||
	    left - sizeof(struct ebt_entry_match) < m->match_size)
		return -EINVAL;

	match = xt_request_find_match(NFPROTO_BRIDGE, m->u.name, 0);
	if (IS_ERR(match))
		return PTR_ERR(match);
	m->u.match = match;

	par->match     = match;
	par->matchinfo = m->data;
	ret = xt_check_match(par, m->match_size,
	      e->ethproto, e->invflags & EBT_IPROTO);
	if (ret < 0) {
		module_put(match->me);
		return ret;
	}

	(*cnt)++;
	return 0;
}

static inline int
ebt_check_watcher(struct ebt_entry_watcher *w, struct xt_tgchk_param *par,
		  unsigned int *cnt)
{
	const struct ebt_entry *e = par->entryinfo;
	struct xt_target *watcher;
	size_t left = ((char *)e + e->target_offset) - (char *)w;
	int ret;

	if (left < sizeof(struct ebt_entry_watcher) ||
	   left - sizeof(struct ebt_entry_watcher) < w->watcher_size)
		return -EINVAL;

	watcher = xt_request_find_target(NFPROTO_BRIDGE, w->u.name, 0);
	if (IS_ERR(watcher))
		return PTR_ERR(watcher);
	w->u.watcher = watcher;

	par->target   = watcher;
	par->targinfo = w->data;
	ret = xt_check_target(par, w->watcher_size,
	      e->ethproto, e->invflags & EBT_IPROTO);
	if (ret < 0) {
		module_put(watcher->me);
		return ret;
	}

	(*cnt)++;
	return 0;
}

static int ebt_verify_pointers(const struct ebt_replace *repl,
			       struct ebt_table_info *newinfo)
{
	unsigned int limit = repl->entries_size;
	unsigned int valid_hooks = repl->valid_hooks;
	unsigned int offset = 0;
	int i;

	for (i = 0; i < NF_BR_NUMHOOKS; i++)
		newinfo->hook_entry[i] = NULL;

	newinfo->entries_size = repl->entries_size;
	newinfo->nentries = repl->nentries;

	while (offset < limit) {
		size_t left = limit - offset;
		struct ebt_entry *e = (void *)newinfo->entries + offset;

		if (left < sizeof(unsigned int))
			break;

		for (i = 0; i < NF_BR_NUMHOOKS; i++) {
			if ((valid_hooks & (1 << i)) == 0)
				continue;
			if ((char __user *)repl->hook_entry[i] ==
			     repl->entries + offset)
				break;
		}

		if (i != NF_BR_NUMHOOKS || !(e->bitmask & EBT_ENTRY_OR_ENTRIES)) {
			if (e->bitmask != 0) {
				/* we make userspace set this right,
				   so there is no misunderstanding */
				BUGPRINT("EBT_ENTRY_OR_ENTRIES shouldn't be set "
					 "in distinguisher\n");
				return -EINVAL;
			}
			if (i != NF_BR_NUMHOOKS)
				newinfo->hook_entry[i] = (struct ebt_entries *)e;
			if (left < sizeof(struct ebt_entries))
				break;
			offset += sizeof(struct ebt_entries);
		} else {
			if (left < sizeof(struct ebt_entry))
				break;
			if (left < e->next_offset)
				break;
			if (e->next_offset < sizeof(struct ebt_entry))
				return -EINVAL;
			offset += e->next_offset;
		}
	}
	if (offset != limit) {
		BUGPRINT("entries_size too small\n");
		return -EINVAL;
	}

	/* check if all valid hooks have a chain */
	for (i = 0; i < NF_BR_NUMHOOKS; i++) {
		if (!newinfo->hook_entry[i] &&
		   (valid_hooks & (1 << i))) {
			BUGPRINT("Valid hook without chain\n");
			return -EINVAL;
		}
	}
	return 0;
}

/*
 * this one is very careful, as it is the first function
 * to parse the userspace data
 */
static inline int
ebt_check_entry_size_and_hooks(const struct ebt_entry *e,
   const struct ebt_table_info *newinfo,
   unsigned int *n, unsigned int *cnt,
   unsigned int *totalcnt, unsigned int *udc_cnt)
{
	int i;

	for (i = 0; i < NF_BR_NUMHOOKS; i++) {
		if ((void *)e == (void *)newinfo->hook_entry[i])
			break;
	}
	/* beginning of a new chain
	   if i == NF_BR_NUMHOOKS it must be a user defined chain */
	if (i != NF_BR_NUMHOOKS || !e->bitmask) {
		/* this checks if the previous chain has as many entries
		   as it said it has */
		if (*n != *cnt) {
			BUGPRINT("nentries does not equal the nr of entries "
				 "in the chain\n");
			return -EINVAL;
		}
		if (((struct ebt_entries *)e)->policy != EBT_DROP &&
		   ((struct ebt_entries *)e)->policy != EBT_ACCEPT) {
			/* only RETURN from udc */
			if (i != NF_BR_NUMHOOKS ||
			   ((struct ebt_entries *)e)->policy != EBT_RETURN) {
				BUGPRINT("bad policy\n");
				return -EINVAL;
			}
		}
		if (i == NF_BR_NUMHOOKS) /* it's a user defined chain */
			(*udc_cnt)++;
		if (((struct ebt_entries *)e)->counter_offset != *totalcnt) {
			BUGPRINT("counter_offset != totalcnt");
			return -EINVAL;
		}
		*n = ((struct ebt_entries *)e)->nentries;
		*cnt = 0;
		return 0;
	}
	/* a plain old entry, heh */
	if (sizeof(struct ebt_entry) > e->watchers_offset ||
	   e->watchers_offset > e->target_offset ||
	   e->target_offset >= e->next_offset) {
		BUGPRINT("entry offsets not in right order\n");
		return -EINVAL;
	}
	/* this is not checked anywhere else */
	if (e->next_offset - e->target_offset < sizeof(struct ebt_entry_target)) {
		BUGPRINT("target size too small\n");
		return -EINVAL;
	}
	(*cnt)++;
	(*totalcnt)++;
	return 0;
}

struct ebt_cl_stack
{
	struct ebt_chainstack cs;
	int from;
	unsigned int hookmask;
};

/*
 * we need these positions to check that the jumps to a different part of the
 * entries is a jump to the beginning of a new chain.
 */
static inline int
ebt_get_udc_positions(struct ebt_entry *e, struct ebt_table_info *newinfo,
   unsigned int *n, struct ebt_cl_stack *udc)
{
	int i;

	/* we're only interested in chain starts */
	if (e->bitmask)
		return 0;
	for (i = 0; i < NF_BR_NUMHOOKS; i++) {
		if (newinfo->hook_entry[i] == (struct ebt_entries *)e)
			break;
	}
	/* only care about udc */
	if (i != NF_BR_NUMHOOKS)
		return 0;

	udc[*n].cs.chaininfo = (struct ebt_entries *)e;
	/* these initialisations are depended on later in check_chainloops() */
	udc[*n].cs.n = 0;
	udc[*n].hookmask = 0;

	(*n)++;
	return 0;
}

static inline int
ebt_cleanup_match(struct ebt_entry_match *m, struct net *net, unsigned int *i)
{
	struct xt_mtdtor_param par;

	if (i && (*i)-- == 0)
		return 1;

	par.net       = net;
	par.match     = m->u.match;
	par.matchinfo = m->data;
	par.family    = NFPROTO_BRIDGE;
	if (par.match->destroy != NULL)
		par.match->destroy(&par);
	module_put(par.match->me);
	return 0;
}

static inline int
ebt_cleanup_watcher(struct ebt_entry_watcher *w, struct net *net, unsigned int *i)
{
	struct xt_tgdtor_param par;

	if (i && (*i)-- == 0)
		return 1;

	par.net      = net;
	par.target   = w->u.watcher;
	par.targinfo = w->data;
	par.family   = NFPROTO_BRIDGE;
	if (par.target->destroy != NULL)
		par.target->destroy(&par);
	module_put(par.target->me);
	return 0;
}

static inline int
ebt_cleanup_entry(struct ebt_entry *e, struct net *net, unsigned int *cnt)
{
	struct xt_tgdtor_param par;
	struct ebt_entry_target *t;

	if (e->bitmask == 0)
		return 0;
	/* we're done */
	if (cnt && (*cnt)-- == 0)
		return 1;
	EBT_WATCHER_ITERATE(e, ebt_cleanup_watcher, net, NULL);
	EBT_MATCH_ITERATE(e, ebt_cleanup_match, net, NULL);
	t = (struct ebt_entry_target *)(((char *)e) + e->target_offset);

	par.net      = net;
	par.target   = t->u.target;
	par.targinfo = t->data;
	par.family   = NFPROTO_BRIDGE;
	if (par.target->destroy != NULL)
		par.target->destroy(&par);
	module_put(par.target->me);
	return 0;
}

static inline int
ebt_check_entry(struct ebt_entry *e, struct net *net,
   const struct ebt_table_info *newinfo,
   const char *name, unsigned int *cnt,
   struct ebt_cl_stack *cl_s, unsigned int udc_cnt)
{
	struct ebt_entry_target *t;
	struct xt_target *target;
	unsigned int i, j, hook = 0, hookmask = 0;
	size_t gap;
	int ret;
	struct xt_mtchk_param mtpar;
	struct xt_tgchk_param tgpar;

	/* don't mess with the struct ebt_entries */
	if (e->bitmask == 0)
		return 0;

	if (e->bitmask & ~EBT_F_MASK) {
		BUGPRINT("Unknown flag for bitmask\n");
		return -EINVAL;
	}
	if (e->invflags & ~EBT_INV_MASK) {
		BUGPRINT("Unknown flag for inv bitmask\n");
		return -EINVAL;
	}
	if ( (e->bitmask & EBT_NOPROTO) && (e->bitmask & EBT_802_3) ) {
		BUGPRINT("NOPROTO & 802_3 not allowed\n");
		return -EINVAL;
	}
	/* what hook do we belong to? */
	for (i = 0; i < NF_BR_NUMHOOKS; i++) {
		if (!newinfo->hook_entry[i])
			continue;
		if ((char *)newinfo->hook_entry[i] < (char *)e)
			hook = i;
		else
			break;
	}
	/* (1 << NF_BR_NUMHOOKS) tells the check functions the rule is on
	   a base chain */
	if (i < NF_BR_NUMHOOKS)
		hookmask = (1 << hook) | (1 << NF_BR_NUMHOOKS);
	else {
		for (i = 0; i < udc_cnt; i++)
			if ((char *)(cl_s[i].cs.chaininfo) > (char *)e)
				break;
		if (i == 0)
			hookmask = (1 << hook) | (1 << NF_BR_NUMHOOKS);
		else
			hookmask = cl_s[i - 1].hookmask;
	}
	i = 0;

	mtpar.net	= tgpar.net       = net;
	mtpar.table     = tgpar.table     = name;
	mtpar.entryinfo = tgpar.entryinfo = e;
	mtpar.hook_mask = tgpar.hook_mask = hookmask;
	mtpar.family    = tgpar.family    = NFPROTO_BRIDGE;
	ret = EBT_MATCH_ITERATE(e, ebt_check_match, &mtpar, &i);
	if (ret != 0)
		goto cleanup_matches;
	j = 0;
	ret = EBT_WATCHER_ITERATE(e, ebt_check_watcher, &tgpar, &j);
	if (ret != 0)
		goto cleanup_watchers;
	t = (struct ebt_entry_target *)(((char *)e) + e->target_offset);
	gap = e->next_offset - e->target_offset;

	target = xt_request_find_target(NFPROTO_BRIDGE, t->u.name, 0);
	if (IS_ERR(target)) {
		ret = PTR_ERR(target);
		goto cleanup_watchers;
	}

	t->u.target = target;
	if (t->u.target == &ebt_standard_target) {
		if (gap < sizeof(struct ebt_standard_target)) {
			BUGPRINT("Standard target size too big\n");
			ret = -EFAULT;
			goto cleanup_watchers;
		}
		if (((struct ebt_standard_target *)t)->verdict <
		   -NUM_STANDARD_TARGETS) {
			BUGPRINT("Invalid standard target\n");
			ret = -EFAULT;
			goto cleanup_watchers;
		}
	} else if (t->target_size > gap - sizeof(struct ebt_entry_target)) {
		module_put(t->u.target->me);
		ret = -EFAULT;
		goto cleanup_watchers;
	}

	tgpar.target   = target;
	tgpar.targinfo = t->data;
	ret = xt_check_target(&tgpar, t->target_size,
	      e->ethproto, e->invflags & EBT_IPROTO);
	if (ret < 0) {
		module_put(target->me);
		goto cleanup_watchers;
	}
	(*cnt)++;
	return 0;
cleanup_watchers:
	EBT_WATCHER_ITERATE(e, ebt_cleanup_watcher, net, &j);
cleanup_matches:
	EBT_MATCH_ITERATE(e, ebt_cleanup_match, net, &i);
	return ret;
}

/*
 * checks for loops and sets the hook mask for udc
 * the hook mask for udc tells us from which base chains the udc can be
 * accessed. This mask is a parameter to the check() functions of the extensions
 */
static int check_chainloops(const struct ebt_entries *chain, struct ebt_cl_stack *cl_s,
   unsigned int udc_cnt, unsigned int hooknr, char *base)
{
	int i, chain_nr = -1, pos = 0, nentries = chain->nentries, verdict;
	const struct ebt_entry *e = (struct ebt_entry *)chain->data;
	const struct ebt_entry_target *t;

	while (pos < nentries || chain_nr != -1) {
		/* end of udc, go back one 'recursion' step */
		if (pos == nentries) {
			/* put back values of the time when this chain was called */
			e = cl_s[chain_nr].cs.e;
			if (cl_s[chain_nr].from != -1)
				nentries =
				cl_s[cl_s[chain_nr].from].cs.chaininfo->nentries;
			else
				nentries = chain->nentries;
			pos = cl_s[chain_nr].cs.n;
			/* make sure we won't see a loop that isn't one */
			cl_s[chain_nr].cs.n = 0;
			chain_nr = cl_s[chain_nr].from;
			if (pos == nentries)
				continue;
		}
		t = (struct ebt_entry_target *)
		   (((char *)e) + e->target_offset);
		if (strcmp(t->u.name, EBT_STANDARD_TARGET))
			goto letscontinue;
		if (e->target_offset + sizeof(struct ebt_standard_target) >
		   e->next_offset) {
			BUGPRINT("Standard target size too big\n");
			return -1;
		}
		verdict = ((struct ebt_standard_target *)t)->verdict;
		if (verdict >= 0) { /* jump to another chain */
			struct ebt_entries *hlp2 =
			   (struct ebt_entries *)(base + verdict);
			for (i = 0; i < udc_cnt; i++)
				if (hlp2 == cl_s[i].cs.chaininfo)
					break;
			/* bad destination or loop */
			if (i == udc_cnt) {
				BUGPRINT("bad destination\n");
				return -1;
			}
			if (cl_s[i].cs.n) {
				BUGPRINT("loop\n");
				return -1;
			}
			if (cl_s[i].hookmask & (1 << hooknr))
				goto letscontinue;
			/* this can't be 0, so the loop test is correct */
			cl_s[i].cs.n = pos + 1;
			pos = 0;
			cl_s[i].cs.e = ebt_next_entry(e);
			e = (struct ebt_entry *)(hlp2->data);
			nentries = hlp2->nentries;
			cl_s[i].from = chain_nr;
			chain_nr = i;
			/* this udc is accessible from the base chain for hooknr */
			cl_s[i].hookmask |= (1 << hooknr);
			continue;
		}
letscontinue:
		e = ebt_next_entry(e);
		pos++;
	}
	return 0;
}

/* do the parsing of the table/chains/entries/matches/watchers/targets, heh */
static int translate_table(struct net *net, const char *name,
			   struct ebt_table_info *newinfo)
{
	unsigned int i, j, k, udc_cnt;
	int ret;
	struct ebt_cl_stack *cl_s = NULL; /* used in the checking for chain loops */

	i = 0;
	while (i < NF_BR_NUMHOOKS && !newinfo->hook_entry[i])
		i++;
	if (i == NF_BR_NUMHOOKS) {
		BUGPRINT("No valid hooks specified\n");
		return -EINVAL;
	}
	if (newinfo->hook_entry[i] != (struct ebt_entries *)newinfo->entries) {
		BUGPRINT("Chains don't start at beginning\n");
		return -EINVAL;
	}
	/* make sure chains are ordered after each other in same order
	   as their corresponding hooks */
	for (j = i + 1; j < NF_BR_NUMHOOKS; j++) {
		if (!newinfo->hook_entry[j])
			continue;
		if (newinfo->hook_entry[j] <= newinfo->hook_entry[i]) {
			BUGPRINT("Hook order must be followed\n");
			return -EINVAL;
		}
		i = j;
	}

	/* do some early checkings and initialize some things */
	i = 0; /* holds the expected nr. of entries for the chain */
	j = 0; /* holds the up to now counted entries for the chain */
	k = 0; /* holds the total nr. of entries, should equal
		  newinfo->nentries afterwards */
	udc_cnt = 0; /* will hold the nr. of user defined chains (udc) */
	ret = EBT_ENTRY_ITERATE(newinfo->entries, newinfo->entries_size,
	   ebt_check_entry_size_and_hooks, newinfo,
	   &i, &j, &k, &udc_cnt);

	if (ret != 0)
		return ret;

	if (i != j) {
		BUGPRINT("nentries does not equal the nr of entries in the "
			 "(last) chain\n");
		return -EINVAL;
	}
	if (k != newinfo->nentries) {
		BUGPRINT("Total nentries is wrong\n");
		return -EINVAL;
	}

	/* get the location of the udc, put them in an array
	   while we're at it, allocate the chainstack */
	if (udc_cnt) {
		/* this will get free'd in do_replace()/ebt_register_table()
		   if an error occurs */
		newinfo->chainstack =
			vmalloc(nr_cpu_ids * sizeof(*(newinfo->chainstack)));
		if (!newinfo->chainstack)
			return -ENOMEM;
		for_each_possible_cpu(i) {
			newinfo->chainstack[i] =
			  vmalloc(udc_cnt * sizeof(*(newinfo->chainstack[0])));
			if (!newinfo->chainstack[i]) {
				while (i)
					vfree(newinfo->chainstack[--i]);
				vfree(newinfo->chainstack);
				newinfo->chainstack = NULL;
				return -ENOMEM;
			}
		}

		cl_s = vmalloc(udc_cnt * sizeof(*cl_s));
		if (!cl_s)
			return -ENOMEM;
		i = 0; /* the i'th udc */
		EBT_ENTRY_ITERATE(newinfo->entries, newinfo->entries_size,
		   ebt_get_udc_positions, newinfo, &i, cl_s);
		/* sanity check */
		if (i != udc_cnt) {
			BUGPRINT("i != udc_cnt\n");
			vfree(cl_s);
			return -EFAULT;
		}
	}

	/* Check for loops */
	for (i = 0; i < NF_BR_NUMHOOKS; i++)
		if (newinfo->hook_entry[i])
			if (check_chainloops(newinfo->hook_entry[i],
			   cl_s, udc_cnt, i, newinfo->entries)) {
				vfree(cl_s);
				return -EINVAL;
			}

	/* we now know the following (along with E=mc²):
	   - the nr of entries in each chain is right
	   - the size of the allocated space is right
	   - all valid hooks have a corresponding chain
	   - there are no loops
	   - wrong data can still be on the level of a single entry
	   - could be there are jumps to places that are not the
	     beginning of a chain. This can only occur in chains that
	     are not accessible from any base chains, so we don't care. */

	/* used to know what we need to clean up if something goes wrong */
	i = 0;
	ret = EBT_ENTRY_ITERATE(newinfo->entries, newinfo->entries_size,
	   ebt_check_entry, net, newinfo, name, &i, cl_s, udc_cnt);
	if (ret != 0) {
		EBT_ENTRY_ITERATE(newinfo->entries, newinfo->entries_size,
				  ebt_cleanup_entry, net, &i);
	}
	vfree(cl_s);
	return ret;
}

/* called under write_lock */
static void get_counters(const struct ebt_counter *oldcounters,
   struct ebt_counter *counters, unsigned int nentries)
{
	int i, cpu;
	struct ebt_counter *counter_base;

	/* counters of cpu 0 */
	memcpy(counters, oldcounters,
	       sizeof(struct ebt_counter) * nentries);

	/* add other counters to those of cpu 0 */
	for_each_possible_cpu(cpu) {
		if (cpu == 0)
			continue;
		counter_base = COUNTER_BASE(oldcounters, nentries, cpu);
		for (i = 0; i < nentries; i++) {
			counters[i].pcnt += counter_base[i].pcnt;
			counters[i].bcnt += counter_base[i].bcnt;
		}
	}
}

static int do_replace_finish(struct net *net, struct ebt_replace *repl,
			      struct ebt_table_info *newinfo)
{
	int ret, i;
	struct ebt_counter *counterstmp = NULL;
	/* used to be able to unlock earlier */
	struct ebt_table_info *table;
	struct ebt_table *t;

	/* the user wants counters back
	   the check on the size is done later, when we have the lock */
	if (repl->num_counters) {
		unsigned long size = repl->num_counters * sizeof(*counterstmp);
		counterstmp = vmalloc(size);
		if (!counterstmp)
			return -ENOMEM;
	}

	newinfo->chainstack = NULL;
	ret = ebt_verify_pointers(repl, newinfo);
	if (ret != 0)
		goto free_counterstmp;

	ret = translate_table(net, repl->name, newinfo);

	if (ret != 0)
		goto free_counterstmp;

	t = find_table_lock(net, repl->name, &ret, &ebt_mutex);
	if (!t) {
		ret = -ENOENT;
		goto free_iterate;
	}

	/* the table doesn't like it */
	if (t->check && (ret = t->check(newinfo, repl->valid_hooks)))
		goto free_unlock;

	if (repl->num_counters && repl->num_counters != t->private->nentries) {
		BUGPRINT("Wrong nr. of counters requested\n");
		ret = -EINVAL;
		goto free_unlock;
	}

	/* we have the mutex lock, so no danger in reading this pointer */
	table = t->private;
	/* make sure the table can only be rmmod'ed if it contains no rules */
	if (!table->nentries && newinfo->nentries && !try_module_get(t->me)) {
		ret = -ENOENT;
		goto free_unlock;
	} else if (table->nentries && !newinfo->nentries)
		module_put(t->me);
	/* we need an atomic snapshot of the counters */
	write_lock_bh(&t->lock);
	if (repl->num_counters)
		get_counters(t->private->counters, counterstmp,
		   t->private->nentries);

	t->private = newinfo;
	write_unlock_bh(&t->lock);
	mutex_unlock(&ebt_mutex);
	/* so, a user can change the chains while having messed up her counter
	   allocation. Only reason why this is done is because this way the lock
	   is held only once, while this doesn't bring the kernel into a
	   dangerous state. */
	if (repl->num_counters &&
	   copy_to_user(repl->counters, counterstmp,
	   repl->num_counters * sizeof(struct ebt_counter))) {
		/* Silent error, can't fail, new table is already in place */
		net_warn_ratelimited("ebtables: counters copy to user failed while replacing table\n");
	}

	/* decrease module count and free resources */
	EBT_ENTRY_ITERATE(table->entries, table->entries_size,
			  ebt_cleanup_entry, net, NULL);

	vfree(table->entries);
	if (table->chainstack) {
		for_each_possible_cpu(i)
			vfree(table->chainstack[i]);
		vfree(table->chainstack);
	}
	vfree(table);

	vfree(counterstmp);
	return ret;

free_unlock:
	mutex_unlock(&ebt_mutex);
free_iterate:
	EBT_ENTRY_ITERATE(newinfo->entries, newinfo->entries_size,
			  ebt_cleanup_entry, net, NULL);
free_counterstmp:
	vfree(counterstmp);
	/* can be initialized in translate_table() */
	if (newinfo->chainstack) {
		for_each_possible_cpu(i)
			vfree(newinfo->chainstack[i]);
		vfree(newinfo->chainstack);
	}
	return ret;
}

/* replace the table */
static int do_replace(struct net *net, const void __user *user,
		      unsigned int len)
{
	int ret, countersize;
	struct ebt_table_info *newinfo;
	struct ebt_replace tmp;

	if (copy_from_user(&tmp, user, sizeof(tmp)) != 0)
		return -EFAULT;

	if (len != sizeof(tmp) + tmp.entries_size) {
		BUGPRINT("Wrong len argument\n");
		return -EINVAL;
	}

	if (tmp.entries_size == 0) {
		BUGPRINT("Entries_size never zero\n");
		return -EINVAL;
	}
	/* overflow check */
	if (tmp.nentries >= ((INT_MAX - sizeof(struct ebt_table_info)) /
			NR_CPUS - SMP_CACHE_BYTES) / sizeof(struct ebt_counter))
		return -ENOMEM;
	if (tmp.num_counters >= INT_MAX / sizeof(struct ebt_counter))
		return -ENOMEM;

	tmp.name[sizeof(tmp.name) - 1] = 0;

	countersize = COUNTER_OFFSET(tmp.nentries) * nr_cpu_ids;
	newinfo = vmalloc(sizeof(*newinfo) + countersize);
	if (!newinfo)
		return -ENOMEM;

	if (countersize)
		memset(newinfo->counters, 0, countersize);

	newinfo->entries = vmalloc(tmp.entries_size);
	if (!newinfo->entries) {
		ret = -ENOMEM;
		goto free_newinfo;
	}
	if (copy_from_user(
	   newinfo->entries, tmp.entries, tmp.entries_size) != 0) {
		BUGPRINT("Couldn't copy entries from userspace\n");
		ret = -EFAULT;
		goto free_entries;
	}

	ret = do_replace_finish(net, &tmp, newinfo);
	if (ret == 0)
		return ret;
free_entries:
	vfree(newinfo->entries);
free_newinfo:
	vfree(newinfo);
	return ret;
}

struct ebt_table *
ebt_register_table(struct net *net, const struct ebt_table *input_table)
{
	struct ebt_table_info *newinfo;
	struct ebt_table *t, *table;
	struct ebt_replace_kernel *repl;
	int ret, i, countersize;
	void *p;

	if (input_table == NULL || (repl = input_table->table) == NULL ||
	    repl->entries == NULL || repl->entries_size == 0 ||
	    repl->counters != NULL || input_table->private != NULL) {
		BUGPRINT("Bad table data for ebt_register_table!!!\n");
		return ERR_PTR(-EINVAL);
	}

	/* Don't add one table to multiple lists. */
	table = kmemdup(input_table, sizeof(struct ebt_table), GFP_KERNEL);
	if (!table) {
		ret = -ENOMEM;
		goto out;
	}

	countersize = COUNTER_OFFSET(repl->nentries) * nr_cpu_ids;
	newinfo = vmalloc(sizeof(*newinfo) + countersize);
	ret = -ENOMEM;
	if (!newinfo)
		goto free_table;

	p = vmalloc(repl->entries_size);
	if (!p)
		goto free_newinfo;

	memcpy(p, repl->entries, repl->entries_size);
	newinfo->entries = p;

	newinfo->entries_size = repl->entries_size;
	newinfo->nentries = repl->nentries;

	if (countersize)
		memset(newinfo->counters, 0, countersize);

	/* fill in newinfo and parse the entries */
	newinfo->chainstack = NULL;
	for (i = 0; i < NF_BR_NUMHOOKS; i++) {
		if ((repl->valid_hooks & (1 << i)) == 0)
			newinfo->hook_entry[i] = NULL;
		else
			newinfo->hook_entry[i] = p +
				((char *)repl->hook_entry[i] - repl->entries);
	}
	ret = translate_table(net, repl->name, newinfo);
	if (ret != 0) {
		BUGPRINT("Translate_table failed\n");
		goto free_chainstack;
	}

	if (table->check && table->check(newinfo, table->valid_hooks)) {
		BUGPRINT("The table doesn't like its own initial data, lol\n");
		ret = -EINVAL;
		goto free_chainstack;
	}

	table->private = newinfo;
	rwlock_init(&table->lock);
	mutex_lock(&ebt_mutex);
	list_for_each_entry(t, &net->xt.tables[NFPROTO_BRIDGE], list) {
		if (strcmp(t->name, table->name) == 0) {
			ret = -EEXIST;
			BUGPRINT("Table name already exists\n");
			goto free_unlock;
		}
	}

	/* Hold a reference count if the chains aren't empty */
	if (newinfo->nentries && !try_module_get(table->me)) {
		ret = -ENOENT;
		goto free_unlock;
	}
	list_add(&table->list, &net->xt.tables[NFPROTO_BRIDGE]);
	mutex_unlock(&ebt_mutex);
	return table;
free_unlock:
	mutex_unlock(&ebt_mutex);
free_chainstack:
	if (newinfo->chainstack) {
		for_each_possible_cpu(i)
			vfree(newinfo->chainstack[i]);
		vfree(newinfo->chainstack);
	}
	vfree(newinfo->entries);
free_newinfo:
	vfree(newinfo);
free_table:
	kfree(table);
out:
	return ERR_PTR(ret);
}

void ebt_unregister_table(struct net *net, struct ebt_table *table)
{
	int i;

	if (!table) {
		BUGPRINT("Request to unregister NULL table!!!\n");
		return;
	}
	mutex_lock(&ebt_mutex);
	list_del(&table->list);
	mutex_unlock(&ebt_mutex);
	EBT_ENTRY_ITERATE(table->private->entries, table->private->entries_size,
			  ebt_cleanup_entry, net, NULL);
	if (table->private->nentries)
		module_put(table->me);
	vfree(table->private->entries);
	if (table->private->chainstack) {
		for_each_possible_cpu(i)
			vfree(table->private->chainstack[i]);
		vfree(table->private->chainstack);
	}
	vfree(table->private);
	kfree(table);
}

/* userspace just supplied us with counters */
static int do_update_counters(struct net *net, const char *name,
				struct ebt_counter __user *counters,
				unsigned int num_counters,
				const void __user *user, unsigned int len)
{
	int i, ret;
	struct ebt_counter *tmp;
	struct ebt_table *t;

	if (num_counters == 0)
		return -EINVAL;

	tmp = vmalloc(num_counters * sizeof(*tmp));
	if (!tmp)
		return -ENOMEM;

	t = find_table_lock(net, name, &ret, &ebt_mutex);
	if (!t)
		goto free_tmp;

	if (num_counters != t->private->nentries) {
		BUGPRINT("Wrong nr of counters\n");
		ret = -EINVAL;
		goto unlock_mutex;
	}

	if (copy_from_user(tmp, counters, num_counters * sizeof(*counters))) {
		ret = -EFAULT;
		goto unlock_mutex;
	}

	/* we want an atomic add of the counters */
	write_lock_bh(&t->lock);

	/* we add to the counters of the first cpu */
	for (i = 0; i < num_counters; i++) {
		t->private->counters[i].pcnt += tmp[i].pcnt;
		t->private->counters[i].bcnt += tmp[i].bcnt;
	}

	write_unlock_bh(&t->lock);
	ret = 0;
unlock_mutex:
	mutex_unlock(&ebt_mutex);
free_tmp:
	vfree(tmp);
	return ret;
}

static int update_counters(struct net *net, const void __user *user,
			    unsigned int len)
{
	struct ebt_replace hlp;

	if (copy_from_user(&hlp, user, sizeof(hlp)))
		return -EFAULT;

	if (len != sizeof(hlp) + hlp.num_counters * sizeof(struct ebt_counter))
		return -EINVAL;

	return do_update_counters(net, hlp.name, hlp.counters,
				hlp.num_counters, user, len);
}

static inline int ebt_make_matchname(const struct ebt_entry_match *m,
    const char *base, char __user *ubase)
{
	char __user *hlp = ubase + ((char *)m - base);
	char name[EBT_FUNCTION_MAXNAMELEN] = {};

	/* ebtables expects 32 bytes long names but xt_match names are 29 bytes
	   long. Copy 29 bytes and fill remaining bytes with zeroes. */
	strlcpy(name, m->u.match->name, sizeof(name));
	if (copy_to_user(hlp, name, EBT_FUNCTION_MAXNAMELEN))
		return -EFAULT;
	return 0;
}

static inline int ebt_make_watchername(const struct ebt_entry_watcher *w,
    const char *base, char __user *ubase)
{
	char __user *hlp = ubase + ((char *)w - base);
	char name[EBT_FUNCTION_MAXNAMELEN] = {};

	strlcpy(name, w->u.watcher->name, sizeof(name));
	if (copy_to_user(hlp , name, EBT_FUNCTION_MAXNAMELEN))
		return -EFAULT;
	return 0;
}

static inline int
ebt_make_names(struct ebt_entry *e, const char *base, char __user *ubase)
{
	int ret;
	char __user *hlp;
	const struct ebt_entry_target *t;
	char name[EBT_FUNCTION_MAXNAMELEN] = {};

	if (e->bitmask == 0)
		return 0;

	hlp = ubase + (((char *)e + e->target_offset) - base);
	t = (struct ebt_entry_target *)(((char *)e) + e->target_offset);

	ret = EBT_MATCH_ITERATE(e, ebt_make_matchname, base, ubase);
	if (ret != 0)
		return ret;
	ret = EBT_WATCHER_ITERATE(e, ebt_make_watchername, base, ubase);
	if (ret != 0)
		return ret;
	strlcpy(name, t->u.target->name, sizeof(name));
	if (copy_to_user(hlp, name, EBT_FUNCTION_MAXNAMELEN))
		return -EFAULT;
	return 0;
}

static int copy_counters_to_user(struct ebt_table *t,
				  const struct ebt_counter *oldcounters,
				  void __user *user, unsigned int num_counters,
				  unsigned int nentries)
{
	struct ebt_counter *counterstmp;
	int ret = 0;

	/* userspace might not need the counters */
	if (num_counters == 0)
		return 0;

	if (num_counters != nentries) {
		BUGPRINT("Num_counters wrong\n");
		return -EINVAL;
	}

	counterstmp = vmalloc(nentries * sizeof(*counterstmp));
	if (!counterstmp)
		return -ENOMEM;

	write_lock_bh(&t->lock);
	get_counters(oldcounters, counterstmp, nentries);
	write_unlock_bh(&t->lock);

	if (copy_to_user(user, counterstmp,
	   nentries * sizeof(struct ebt_counter)))
		ret = -EFAULT;
	vfree(counterstmp);
	return ret;
}

/* called with ebt_mutex locked */
static int copy_everything_to_user(struct ebt_table *t, void __user *user,
    const int *len, int cmd)
{
	struct ebt_replace tmp;
	const struct ebt_counter *oldcounters;
	unsigned int entries_size, nentries;
	int ret;
	char *entries;

	if (cmd == EBT_SO_GET_ENTRIES) {
		entries_size = t->private->entries_size;
		nentries = t->private->nentries;
		entries = t->private->entries;
		oldcounters = t->private->counters;
	} else {
		entries_size = t->table->entries_size;
		nentries = t->table->nentries;
		entries = t->table->entries;
		oldcounters = t->table->counters;
	}

	if (copy_from_user(&tmp, user, sizeof(tmp)))
		return -EFAULT;

	if (*len != sizeof(struct ebt_replace) + entries_size +
	   (tmp.num_counters ? nentries * sizeof(struct ebt_counter) : 0))
		return -EINVAL;

	if (tmp.nentries != nentries) {
		BUGPRINT("Nentries wrong\n");
		return -EINVAL;
	}

	if (tmp.entries_size != entries_size) {
		BUGPRINT("Wrong size\n");
		return -EINVAL;
	}

	ret = copy_counters_to_user(t, oldcounters, tmp.counters,
					tmp.num_counters, nentries);
	if (ret)
		return ret;

	if (copy_to_user(tmp.entries, entries, entries_size)) {
		BUGPRINT("Couldn't copy entries to userspace\n");
		return -EFAULT;
	}
	/* set the match/watcher/target names right */
	return EBT_ENTRY_ITERATE(entries, entries_size,
	   ebt_make_names, entries, tmp.entries);
}

static int do_ebt_set_ctl(struct sock *sk,
	int cmd, void __user *user, unsigned int len)
{
	int ret;
	struct net *net = sock_net(sk);

	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
		return -EPERM;

	switch (cmd) {
	case EBT_SO_SET_ENTRIES:
		ret = do_replace(net, user, len);
		break;
	case EBT_SO_SET_COUNTERS:
		ret = update_counters(net, user, len);
		break;
	default:
		ret = -EINVAL;
	}
	return ret;
}

static int do_ebt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
{
	int ret;
	struct ebt_replace tmp;
	struct ebt_table *t;
	struct net *net = sock_net(sk);

	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
		return -EPERM;

	if (copy_from_user(&tmp, user, sizeof(tmp)))
		return -EFAULT;

	t = find_table_lock(net, tmp.name, &ret, &ebt_mutex);
	if (!t)
		return ret;

	switch (cmd) {
	case EBT_SO_GET_INFO:
	case EBT_SO_GET_INIT_INFO:
		if (*len != sizeof(struct ebt_replace)) {
			ret = -EINVAL;
			mutex_unlock(&ebt_mutex);
			break;
		}
		if (cmd == EBT_SO_GET_INFO) {
			tmp.nentries = t->private->nentries;
			tmp.entries_size = t->private->entries_size;
			tmp.valid_hooks = t->valid_hooks;
		} else {
			tmp.nentries = t->table->nentries;
			tmp.entries_size = t->table->entries_size;
			tmp.valid_hooks = t->table->valid_hooks;
		}
		mutex_unlock(&ebt_mutex);
		if (copy_to_user(user, &tmp, *len) != 0) {
			BUGPRINT("c2u Didn't work\n");
			ret = -EFAULT;
			break;
		}
		ret = 0;
		break;

	case EBT_SO_GET_ENTRIES:
	case EBT_SO_GET_INIT_ENTRIES:
		ret = copy_everything_to_user(t, user, len, cmd);
		mutex_unlock(&ebt_mutex);
		break;

	default:
		mutex_unlock(&ebt_mutex);
		ret = -EINVAL;
	}

	return ret;
}

#ifdef CONFIG_COMPAT
/* 32 bit-userspace compatibility definitions. */
struct compat_ebt_replace {
	char name[EBT_TABLE_MAXNAMELEN];
	compat_uint_t valid_hooks;
	compat_uint_t nentries;
	compat_uint_t entries_size;
	/* start of the chains */
	compat_uptr_t hook_entry[NF_BR_NUMHOOKS];
	/* nr of counters userspace expects back */
	compat_uint_t num_counters;
	/* where the kernel will put the old counters. */
	compat_uptr_t counters;
	compat_uptr_t entries;
};

/* struct ebt_entry_match, _target and _watcher have same layout */
struct compat_ebt_entry_mwt {
	union {
		char name[EBT_FUNCTION_MAXNAMELEN];
		compat_uptr_t ptr;
	} u;
	compat_uint_t match_size;
	compat_uint_t data[0];
};

/* account for possible padding between match_size and ->data */
static int ebt_compat_entry_padsize(void)
{
	BUILD_BUG_ON(XT_ALIGN(sizeof(struct ebt_entry_match)) <
			COMPAT_XT_ALIGN(sizeof(struct compat_ebt_entry_mwt)));
	return (int) XT_ALIGN(sizeof(struct ebt_entry_match)) -
			COMPAT_XT_ALIGN(sizeof(struct compat_ebt_entry_mwt));
}

static int ebt_compat_match_offset(const struct xt_match *match,
				   unsigned int userlen)
{
	/*
	 * ebt_among needs special handling. The kernel .matchsize is
	 * set to -1 at registration time; at runtime an EBT_ALIGN()ed
	 * value is expected.
	 * Example: userspace sends 4500, ebt_among.c wants 4504.
	 */
	if (unlikely(match->matchsize == -1))
		return XT_ALIGN(userlen) - COMPAT_XT_ALIGN(userlen);
	return xt_compat_match_offset(match);
}

static int compat_match_to_user(struct ebt_entry_match *m, void __user **dstptr,
				unsigned int *size)
{
	const struct xt_match *match = m->u.match;
	struct compat_ebt_entry_mwt __user *cm = *dstptr;
	int off = ebt_compat_match_offset(match, m->match_size);
	compat_uint_t msize = m->match_size - off;

	BUG_ON(off >= m->match_size);

	if (copy_to_user(cm->u.name, match->name,
	    strlen(match->name) + 1) || put_user(msize, &cm->match_size))
		return -EFAULT;

	if (match->compat_to_user) {
		if (match->compat_to_user(cm->data, m->data))
			return -EFAULT;
	} else if (copy_to_user(cm->data, m->data, msize))
			return -EFAULT;

	*size -= ebt_compat_entry_padsize() + off;
	*dstptr = cm->data;
	*dstptr += msize;
	return 0;
}

static int compat_target_to_user(struct ebt_entry_target *t,
				 void __user **dstptr,
				 unsigned int *size)
{
	const struct xt_target *target = t->u.target;
	struct compat_ebt_entry_mwt __user *cm = *dstptr;
	int off = xt_compat_target_offset(target);
	compat_uint_t tsize = t->target_size - off;

	BUG_ON(off >= t->target_size);

	if (copy_to_user(cm->u.name, target->name,
	    strlen(target->name) + 1) || put_user(tsize, &cm->match_size))
		return -EFAULT;

	if (target->compat_to_user) {
		if (target->compat_to_user(cm->data, t->data))
			return -EFAULT;
	} else if (copy_to_user(cm->data, t->data, tsize))
		return -EFAULT;

	*size -= ebt_compat_entry_padsize() + off;
	*dstptr = cm->data;
	*dstptr += tsize;
	return 0;
}

static int compat_watcher_to_user(struct ebt_entry_watcher *w,
				  void __user **dstptr,
				  unsigned int *size)
{
	return compat_target_to_user((struct ebt_entry_target *)w,
							dstptr, size);
}

static int compat_copy_entry_to_user(struct ebt_entry *e, void __user **dstptr,
				unsigned int *size)
{
	struct ebt_entry_target *t;
	struct ebt_entry __user *ce;
	u32 watchers_offset, target_offset, next_offset;
	compat_uint_t origsize;
	int ret;

	if (e->bitmask == 0) {
		if (*size < sizeof(struct ebt_entries))
			return -EINVAL;
		if (copy_to_user(*dstptr, e, sizeof(struct ebt_entries)))
			return -EFAULT;

		*dstptr += sizeof(struct ebt_entries);
		*size -= sizeof(struct ebt_entries);
		return 0;
	}

	if (*size < sizeof(*ce))
		return -EINVAL;

	ce = (struct ebt_entry __user *)*dstptr;
	if (copy_to_user(ce, e, sizeof(*ce)))
		return -EFAULT;

	origsize = *size;
	*dstptr += sizeof(*ce);

	ret = EBT_MATCH_ITERATE(e, compat_match_to_user, dstptr, size);
	if (ret)
		return ret;
	watchers_offset = e->watchers_offset - (origsize - *size);

	ret = EBT_WATCHER_ITERATE(e, compat_watcher_to_user, dstptr, size);
	if (ret)
		return ret;
	target_offset = e->target_offset - (origsize - *size);

	t = (struct ebt_entry_target *) ((char *) e + e->target_offset);

	ret = compat_target_to_user(t, dstptr, size);
	if (ret)
		return ret;
	next_offset = e->next_offset - (origsize - *size);

	if (put_user(watchers_offset, &ce->watchers_offset) ||
	    put_user(target_offset, &ce->target_offset) ||
	    put_user(next_offset, &ce->next_offset))
		return -EFAULT;

	*size -= sizeof(*ce);
	return 0;
}

static int compat_calc_match(struct ebt_entry_match *m, int *off)
{
	*off += ebt_compat_match_offset(m->u.match, m->match_size);
	*off += ebt_compat_entry_padsize();
	return 0;
}

static int compat_calc_watcher(struct ebt_entry_watcher *w, int *off)
{
	*off += xt_compat_target_offset(w->u.watcher);
	*off += ebt_compat_entry_padsize();
	return 0;
}

static int compat_calc_entry(const struct ebt_entry *e,
			     const struct ebt_table_info *info,
			     const void *base,
			     struct compat_ebt_replace *newinfo)
{
	const struct ebt_entry_target *t;
	unsigned int entry_offset;
	int off, ret, i;

	if (e->bitmask == 0)
		return 0;

	off = 0;
	entry_offset = (void *)e - base;

	EBT_MATCH_ITERATE(e, compat_calc_match, &off);
	EBT_WATCHER_ITERATE(e, compat_calc_watcher, &off);

	t = (const struct ebt_entry_target *) ((char *) e + e->target_offset);

	off += xt_compat_target_offset(t->u.target);
	off += ebt_compat_entry_padsize();

	newinfo->entries_size -= off;

	ret = xt_compat_add_offset(NFPROTO_BRIDGE, entry_offset, off);
	if (ret)
		return ret;

	for (i = 0; i < NF_BR_NUMHOOKS; i++) {
		const void *hookptr = info->hook_entry[i];
		if (info->hook_entry[i] &&
		    (e < (struct ebt_entry *)(base - hookptr))) {
			newinfo->hook_entry[i] -= off;
			pr_debug("0x%08X -> 0x%08X\n",
					newinfo->hook_entry[i] + off,
					newinfo->hook_entry[i]);
		}
	}

	return 0;
}


static int compat_table_info(const struct ebt_table_info *info,
			     struct compat_ebt_replace *newinfo)
{
	unsigned int size = info->entries_size;
	const void *entries = info->entries;

	newinfo->entries_size = size;

	xt_compat_init_offsets(NFPROTO_BRIDGE, info->nentries);
	return EBT_ENTRY_ITERATE(entries, size, compat_calc_entry, info,
							entries, newinfo);
}

static int compat_copy_everything_to_user(struct ebt_table *t,
					  void __user *user, int *len, int cmd)
{
	struct compat_ebt_replace repl, tmp;
	struct ebt_counter *oldcounters;
	struct ebt_table_info tinfo;
	int ret;
	void __user *pos;

	memset(&tinfo, 0, sizeof(tinfo));

	if (cmd == EBT_SO_GET_ENTRIES) {
		tinfo.entries_size = t->private->entries_size;
		tinfo.nentries = t->private->nentries;
		tinfo.entries = t->private->entries;
		oldcounters = t->private->counters;
	} else {
		tinfo.entries_size = t->table->entries_size;
		tinfo.nentries = t->table->nentries;
		tinfo.entries = t->table->entries;
		oldcounters = t->table->counters;
	}

	if (copy_from_user(&tmp, user, sizeof(tmp)))
		return -EFAULT;

	if (tmp.nentries != tinfo.nentries ||
	   (tmp.num_counters && tmp.num_counters != tinfo.nentries))
		return -EINVAL;

	memcpy(&repl, &tmp, sizeof(repl));
	if (cmd == EBT_SO_GET_ENTRIES)
		ret = compat_table_info(t->private, &repl);
	else
		ret = compat_table_info(&tinfo, &repl);
	if (ret)
		return ret;

	if (*len != sizeof(tmp) + repl.entries_size +
	   (tmp.num_counters? tinfo.nentries * sizeof(struct ebt_counter): 0)) {
		pr_err("wrong size: *len %d, entries_size %u, replsz %d\n",
				*len, tinfo.entries_size, repl.entries_size);
		return -EINVAL;
	}

	/* userspace might not need the counters */
	ret = copy_counters_to_user(t, oldcounters, compat_ptr(tmp.counters),
					tmp.num_counters, tinfo.nentries);
	if (ret)
		return ret;

	pos = compat_ptr(tmp.entries);
	return EBT_ENTRY_ITERATE(tinfo.entries, tinfo.entries_size,
			compat_copy_entry_to_user, &pos, &tmp.entries_size);
}

struct ebt_entries_buf_state {
	char *buf_kern_start;	/* kernel buffer to copy (translated) data to */
	u32 buf_kern_len;	/* total size of kernel buffer */
	u32 buf_kern_offset;	/* amount of data copied so far */
	u32 buf_user_offset;	/* read position in userspace buffer */
};

static int ebt_buf_count(struct ebt_entries_buf_state *state, unsigned int sz)
{
	state->buf_kern_offset += sz;
	return state->buf_kern_offset >= sz ? 0 : -EINVAL;
}

static int ebt_buf_add(struct ebt_entries_buf_state *state,
		       void *data, unsigned int sz)
{
	if (state->buf_kern_start == NULL)
		goto count_only;

	BUG_ON(state->buf_kern_offset + sz > state->buf_kern_len);

	memcpy(state->buf_kern_start + state->buf_kern_offset, data, sz);

 count_only:
	state->buf_user_offset += sz;
	return ebt_buf_count(state, sz);
}

static int ebt_buf_add_pad(struct ebt_entries_buf_state *state, unsigned int sz)
{
	char *b = state->buf_kern_start;

	BUG_ON(b && state->buf_kern_offset > state->buf_kern_len);

	if (b != NULL && sz > 0)
		memset(b + state->buf_kern_offset, 0, sz);
	/* do not adjust ->buf_user_offset here, we added kernel-side padding */
	return ebt_buf_count(state, sz);
}

enum compat_mwt {
	EBT_COMPAT_MATCH,
	EBT_COMPAT_WATCHER,
	EBT_COMPAT_TARGET,
};

static int compat_mtw_from_user(struct compat_ebt_entry_mwt *mwt,
				enum compat_mwt compat_mwt,
				struct ebt_entries_buf_state *state,
				const unsigned char *base)
{
	char name[EBT_FUNCTION_MAXNAMELEN];
	struct xt_match *match;
	struct xt_target *wt;
	void *dst = NULL;
	int off, pad = 0;
	unsigned int size_kern, match_size = mwt->match_size;

	strlcpy(name, mwt->u.name, sizeof(name));

	if (state->buf_kern_start)
		dst = state->buf_kern_start + state->buf_kern_offset;

	switch (compat_mwt) {
	case EBT_COMPAT_MATCH:
		match = xt_request_find_match(NFPROTO_BRIDGE, name, 0);
		if (IS_ERR(match))
			return PTR_ERR(match);

		off = ebt_compat_match_offset(match, match_size);
		if (dst) {
			if (match->compat_from_user)
				match->compat_from_user(dst, mwt->data);
			else
				memcpy(dst, mwt->data, match_size);
		}

		size_kern = match->matchsize;
		if (unlikely(size_kern == -1))
			size_kern = match_size;
		module_put(match->me);
		break;
	case EBT_COMPAT_WATCHER: /* fallthrough */
	case EBT_COMPAT_TARGET:
		wt = xt_request_find_target(NFPROTO_BRIDGE, name, 0);
		if (IS_ERR(wt))
			return PTR_ERR(wt);
		off = xt_compat_target_offset(wt);

		if (dst) {
			if (wt->compat_from_user)
				wt->compat_from_user(dst, mwt->data);
			else
				memcpy(dst, mwt->data, match_size);
		}

		size_kern = wt->targetsize;
		module_put(wt->me);
		break;

	default:
		return -EINVAL;
	}

	state->buf_kern_offset += match_size + off;
	state->buf_user_offset += match_size;
	pad = XT_ALIGN(size_kern) - size_kern;

	if (pad > 0 && dst) {
		BUG_ON(state->buf_kern_len <= pad);
		BUG_ON(state->buf_kern_offset - (match_size + off) + size_kern > state->buf_kern_len - pad);
		memset(dst + size_kern, 0, pad);
	}
	return off + match_size;
}

/*
 * return size of all matches, watchers or target, including necessary
 * alignment and padding.
 */
static int ebt_size_mwt(struct compat_ebt_entry_mwt *match32,
			unsigned int size_left, enum compat_mwt type,
			struct ebt_entries_buf_state *state, const void *base)
{
	int growth = 0;
	char *buf;

	if (size_left == 0)
		return 0;

	buf = (char *) match32;

	while (size_left >= sizeof(*match32)) {
		struct ebt_entry_match *match_kern;
		int ret;

		match_kern = (struct ebt_entry_match *) state->buf_kern_start;
		if (match_kern) {
			char *tmp;
			tmp = state->buf_kern_start + state->buf_kern_offset;
			match_kern = (struct ebt_entry_match *) tmp;
		}
		ret = ebt_buf_add(state, buf, sizeof(*match32));
		if (ret < 0)
			return ret;
		size_left -= sizeof(*match32);

		/* add padding before match->data (if any) */
		ret = ebt_buf_add_pad(state, ebt_compat_entry_padsize());
		if (ret < 0)
			return ret;

		if (match32->match_size > size_left)
			return -EINVAL;

		size_left -= match32->match_size;

		ret = compat_mtw_from_user(match32, type, state, base);
		if (ret < 0)
			return ret;

		BUG_ON(ret < match32->match_size);
		growth += ret - match32->match_size;
		growth += ebt_compat_entry_padsize();

		buf += sizeof(*match32);
		buf += match32->match_size;

		if (match_kern)
			match_kern->match_size = ret;

		WARN_ON(type == EBT_COMPAT_TARGET && size_left);
		match32 = (struct compat_ebt_entry_mwt *) buf;
	}

	return growth;
}

/* called for all ebt_entry structures. */
static int size_entry_mwt(struct ebt_entry *entry, const unsigned char *base,
			  unsigned int *total,
			  struct ebt_entries_buf_state *state)
{
	unsigned int i, j, startoff, new_offset = 0;
	/* stores match/watchers/targets & offset of next struct ebt_entry: */
	unsigned int offsets[4];
	unsigned int *offsets_update = NULL;
	int ret;
	char *buf_start;

	if (*total < sizeof(struct ebt_entries))
		return -EINVAL;

	if (!entry->bitmask) {
		*total -= sizeof(struct ebt_entries);
		return ebt_buf_add(state, entry, sizeof(struct ebt_entries));
	}
	if (*total < sizeof(*entry) || entry->next_offset < sizeof(*entry))
		return -EINVAL;

	startoff = state->buf_user_offset;
	/* pull in most part of ebt_entry, it does not need to be changed. */
	ret = ebt_buf_add(state, entry,
			offsetof(struct ebt_entry, watchers_offset));
	if (ret < 0)
		return ret;

	offsets[0] = sizeof(struct ebt_entry); /* matches come first */
	memcpy(&offsets[1], &entry->watchers_offset,
			sizeof(offsets) - sizeof(offsets[0]));

	if (state->buf_kern_start) {
		buf_start = state->buf_kern_start + state->buf_kern_offset;
		offsets_update = (unsigned int *) buf_start;
	}
	ret = ebt_buf_add(state, &offsets[1],
			sizeof(offsets) - sizeof(offsets[0]));
	if (ret < 0)
		return ret;
	buf_start = (char *) entry;
	/*
	 * 0: matches offset, always follows ebt_entry.
	 * 1: watchers offset, from ebt_entry structure
	 * 2: target offset, from ebt_entry structure
	 * 3: next ebt_entry offset, from ebt_entry structure
	 *
	 * offsets are relative to beginning of struct ebt_entry (i.e., 0).
	 */
	for (i = 0, j = 1 ; j < 4 ; j++, i++) {
		struct compat_ebt_entry_mwt *match32;
		unsigned int size;
		char *buf = buf_start;

		buf = buf_start + offsets[i];
		if (offsets[i] > offsets[j])
			return -EINVAL;

		match32 = (struct compat_ebt_entry_mwt *) buf;
		size = offsets[j] - offsets[i];
		ret = ebt_size_mwt(match32, size, i, state, base);
		if (ret < 0)
			return ret;
		new_offset += ret;
		if (offsets_update && new_offset) {
			pr_debug("change offset %d to %d\n",
				offsets_update[i], offsets[j] + new_offset);
			offsets_update[i] = offsets[j] + new_offset;
		}
	}

	if (state->buf_kern_start == NULL) {
		unsigned int offset = buf_start - (char *) base;

		ret = xt_compat_add_offset(NFPROTO_BRIDGE, offset, new_offset);
		if (ret < 0)
			return ret;
	}

	startoff = state->buf_user_offset - startoff;

	BUG_ON(*total < startoff);
	*total -= startoff;
	return 0;
}

/*
 * repl->entries_size is the size of the ebt_entry blob in userspace.
 * It might need more memory when copied to a 64 bit kernel in case
 * userspace is 32-bit. So, first task: find out how much memory is needed.
 *
 * Called before validation is performed.
 */
static int compat_copy_entries(unsigned char *data, unsigned int size_user,
				struct ebt_entries_buf_state *state)
{
	unsigned int size_remaining = size_user;
	int ret;

	ret = EBT_ENTRY_ITERATE(data, size_user, size_entry_mwt, data,
					&size_remaining, state);
	if (ret < 0)
		return ret;

	WARN_ON(size_remaining);
	return state->buf_kern_offset;
}


static int compat_copy_ebt_replace_from_user(struct ebt_replace *repl,
					    void __user *user, unsigned int len)
{
	struct compat_ebt_replace tmp;
	int i;

	if (len < sizeof(tmp))
		return -EINVAL;

	if (copy_from_user(&tmp, user, sizeof(tmp)))
		return -EFAULT;

	if (len != sizeof(tmp) + tmp.entries_size)
		return -EINVAL;

	if (tmp.entries_size == 0)
		return -EINVAL;

	if (tmp.nentries >= ((INT_MAX - sizeof(struct ebt_table_info)) /
			NR_CPUS - SMP_CACHE_BYTES) / sizeof(struct ebt_counter))
		return -ENOMEM;
	if (tmp.num_counters >= INT_MAX / sizeof(struct ebt_counter))
		return -ENOMEM;

	memcpy(repl, &tmp, offsetof(struct ebt_replace, hook_entry));

	/* starting with hook_entry, 32 vs. 64 bit structures are different */
	for (i = 0; i < NF_BR_NUMHOOKS; i++)
		repl->hook_entry[i] = compat_ptr(tmp.hook_entry[i]);

	repl->num_counters = tmp.num_counters;
	repl->counters = compat_ptr(tmp.counters);
	repl->entries = compat_ptr(tmp.entries);
	return 0;
}

static int compat_do_replace(struct net *net, void __user *user,
			     unsigned int len)
{
	int ret, i, countersize, size64;
	struct ebt_table_info *newinfo;
	struct ebt_replace tmp;
	struct ebt_entries_buf_state state;
	void *entries_tmp;

	ret = compat_copy_ebt_replace_from_user(&tmp, user, len);
	if (ret) {
		/* try real handler in case userland supplied needed padding */
		if (ret == -EINVAL && do_replace(net, user, len) == 0)
			ret = 0;
		return ret;
	}

	countersize = COUNTER_OFFSET(tmp.nentries) * nr_cpu_ids;
	newinfo = vmalloc(sizeof(*newinfo) + countersize);
	if (!newinfo)
		return -ENOMEM;

	if (countersize)
		memset(newinfo->counters, 0, countersize);

	memset(&state, 0, sizeof(state));

	newinfo->entries = vmalloc(tmp.entries_size);
	if (!newinfo->entries) {
		ret = -ENOMEM;
		goto free_newinfo;
	}
	if (copy_from_user(
	   newinfo->entries, tmp.entries, tmp.entries_size) != 0) {
		ret = -EFAULT;
		goto free_entries;
	}

	entries_tmp = newinfo->entries;

	xt_compat_lock(NFPROTO_BRIDGE);

	xt_compat_init_offsets(NFPROTO_BRIDGE, tmp.nentries);
	ret = compat_copy_entries(entries_tmp, tmp.entries_size, &state);
	if (ret < 0)
		goto out_unlock;

	pr_debug("tmp.entries_size %d, kern off %d, user off %d delta %d\n",
		tmp.entries_size, state.buf_kern_offset, state.buf_user_offset,
		xt_compat_calc_jump(NFPROTO_BRIDGE, tmp.entries_size));

	size64 = ret;
	newinfo->entries = vmalloc(size64);
	if (!newinfo->entries) {
		vfree(entries_tmp);
		ret = -ENOMEM;
		goto out_unlock;
	}

	memset(&state, 0, sizeof(state));
	state.buf_kern_start = newinfo->entries;
	state.buf_kern_len = size64;

	ret = compat_copy_entries(entries_tmp, tmp.entries_size, &state);
	BUG_ON(ret < 0);	/* parses same data again */

	vfree(entries_tmp);
	tmp.entries_size = size64;

	for (i = 0; i < NF_BR_NUMHOOKS; i++) {
		char __user *usrptr;
		if (tmp.hook_entry[i]) {
			unsigned int delta;
			usrptr = (char __user *) tmp.hook_entry[i];
			delta = usrptr - tmp.entries;
			usrptr += xt_compat_calc_jump(NFPROTO_BRIDGE, delta);
			tmp.hook_entry[i] = (struct ebt_entries __user *)usrptr;
		}
	}

	xt_compat_flush_offsets(NFPROTO_BRIDGE);
	xt_compat_unlock(NFPROTO_BRIDGE);

	ret = do_replace_finish(net, &tmp, newinfo);
	if (ret == 0)
		return ret;
free_entries:
	vfree(newinfo->entries);
free_newinfo:
	vfree(newinfo);
	return ret;
out_unlock:
	xt_compat_flush_offsets(NFPROTO_BRIDGE);
	xt_compat_unlock(NFPROTO_BRIDGE);
	goto free_entries;
}

static int compat_update_counters(struct net *net, void __user *user,
				  unsigned int len)
{
	struct compat_ebt_replace hlp;

	if (copy_from_user(&hlp, user, sizeof(hlp)))
		return -EFAULT;

	/* try real handler in case userland supplied needed padding */
	if (len != sizeof(hlp) + hlp.num_counters * sizeof(struct ebt_counter))
		return update_counters(net, user, len);

	return do_update_counters(net, hlp.name, compat_ptr(hlp.counters),
					hlp.num_counters, user, len);
}

static int compat_do_ebt_set_ctl(struct sock *sk,
		int cmd, void __user *user, unsigned int len)
{
	int ret;
	struct net *net = sock_net(sk);

	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
		return -EPERM;

	switch (cmd) {
	case EBT_SO_SET_ENTRIES:
		ret = compat_do_replace(net, user, len);
		break;
	case EBT_SO_SET_COUNTERS:
		ret = compat_update_counters(net, user, len);
		break;
	default:
		ret = -EINVAL;
  }
	return ret;
}

static int compat_do_ebt_get_ctl(struct sock *sk, int cmd,
		void __user *user, int *len)
{
	int ret;
	struct compat_ebt_replace tmp;
	struct ebt_table *t;
	struct net *net = sock_net(sk);

	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
		return -EPERM;

	/* try real handler in case userland supplied needed padding */
	if ((cmd == EBT_SO_GET_INFO ||
	     cmd == EBT_SO_GET_INIT_INFO) && *len != sizeof(tmp))
			return do_ebt_get_ctl(sk, cmd, user, len);

	if (copy_from_user(&tmp, user, sizeof(tmp)))
		return -EFAULT;

	t = find_table_lock(net, tmp.name, &ret, &ebt_mutex);
	if (!t)
		return ret;

	xt_compat_lock(NFPROTO_BRIDGE);
	switch (cmd) {
	case EBT_SO_GET_INFO:
		tmp.nentries = t->private->nentries;
		ret = compat_table_info(t->private, &tmp);
		if (ret)
			goto out;
		tmp.valid_hooks = t->valid_hooks;

		if (copy_to_user(user, &tmp, *len) != 0) {
			ret = -EFAULT;
			break;
		}
		ret = 0;
		break;
	case EBT_SO_GET_INIT_INFO:
		tmp.nentries = t->table->nentries;
		tmp.entries_size = t->table->entries_size;
		tmp.valid_hooks = t->table->valid_hooks;

		if (copy_to_user(user, &tmp, *len) != 0) {
			ret = -EFAULT;
			break;
		}
		ret = 0;
		break;
	case EBT_SO_GET_ENTRIES:
	case EBT_SO_GET_INIT_ENTRIES:
		/*
		 * try real handler first in case of userland-side padding.
		 * in case we are dealing with an 'ordinary' 32 bit binary
		 * without 64bit compatibility padding, this will fail right
		 * after copy_from_user when the *len argument is validated.
		 *
		 * the compat_ variant needs to do one pass over the kernel
		 * data set to adjust for size differences before it the check.
		 */
		if (copy_everything_to_user(t, user, len, cmd) == 0)
			ret = 0;
		else
			ret = compat_copy_everything_to_user(t, user, len, cmd);
		break;
	default:
		ret = -EINVAL;
	}
 out:
	xt_compat_flush_offsets(NFPROTO_BRIDGE);
	xt_compat_unlock(NFPROTO_BRIDGE);
	mutex_unlock(&ebt_mutex);
	return ret;
}
#endif

static struct nf_sockopt_ops ebt_sockopts = {
	.pf		= PF_INET,
	.set_optmin	= EBT_BASE_CTL,
	.set_optmax	= EBT_SO_SET_MAX + 1,
	.set		= do_ebt_set_ctl,
#ifdef CONFIG_COMPAT
	.compat_set	= compat_do_ebt_set_ctl,
#endif
	.get_optmin	= EBT_BASE_CTL,
	.get_optmax	= EBT_SO_GET_MAX + 1,
	.get		= do_ebt_get_ctl,
#ifdef CONFIG_COMPAT
	.compat_get	= compat_do_ebt_get_ctl,
#endif
	.owner		= THIS_MODULE,
};

static int __init ebtables_init(void)
{
	int ret;

	ret = xt_register_target(&ebt_standard_target);
	if (ret < 0)
		return ret;
	ret = nf_register_sockopt(&ebt_sockopts);
	if (ret < 0) {
		xt_unregister_target(&ebt_standard_target);
		return ret;
	}

	printk(KERN_INFO "Ebtables v2.0 registered\n");
	return 0;
}

static void __exit ebtables_fini(void)
{
	nf_unregister_sockopt(&ebt_sockopts);
	xt_unregister_target(&ebt_standard_target);
	printk(KERN_INFO "Ebtables v2.0 unregistered\n");
}

EXPORT_SYMBOL(ebt_register_table);
EXPORT_SYMBOL(ebt_unregister_table);
EXPORT_SYMBOL(ebt_do_table);
module_init(ebtables_init);
module_exit(ebtables_fini);
MODULE_LICENSE("GPL");