Merge tag 'hyperv-fixes-signed' of git://git.kernel.org/pub/scm/linux/kernel/git...

[thirdparty/linux.git] / net / bridge / netfilter / ebtables.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  ebtables
 *
 *  Author:
 *  Bart De Schuymer            <bdschuym@pandora.be>
 *
 *  ebtables.c,v 2.0, July, 2002
 *
 *  This code is strongly inspired by the iptables code which is
 *  Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
 */
#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 <linux/uaccess.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/audit.h>
#include <net/sock.h>
/* needed for logical [in,out]-dev filtering */
#include "../br_private.h"

/* 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);
}

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;
}

/* 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;

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

        if (e->bitmask & EBT_802_3) {
                if (NF_INVF(e, EBT_IPROTO, eth_proto_is_802_3(ethproto)))
                        return 1;
        } else if (!(e->bitmask & EBT_NOPROTO) &&
                   NF_INVF(e, EBT_IPROTO, e->ethproto != ethproto))
                return 1;

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

        if (e->bitmask & EBT_SOURCEMAC) {
                if (NF_INVF(e, EBT_ISOURCE,
                            !ether_addr_equal_masked(h->h_source, e->sourcemac,
                                                     e->sourcemsk)))
                        return 1;
        }
        if (e->bitmask & EBT_DESTMAC) {
                if (NF_INVF(e, EBT_IDEST,
                            !ether_addr_equal_masked(h->h_dest, e->destmac,
                                                     e->destmsk)))
                        return 1;
        }
        return 0;
}

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

static inline const struct ebt_entry_target *
ebt_get_target_c(const struct ebt_entry *e)
{
        return ebt_get_target((struct ebt_entry *)e);
}

/* Do some firewalling */
unsigned int ebt_do_table(struct sk_buff *skb,
                          const struct nf_hook_state *state,
                          struct ebt_table *table)
{
        unsigned int hook = state->hook;
        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.state   = state;
        acpar.hotdrop = false;

        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, state->in, state->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;
                }

                ADD_COUNTER(*(counter_base + i), 1, 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 = ebt_get_target_c(point);
                /* 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:
                        if (WARN(sp == 0, "RETURN on base chain")) {
                                /* act like this is EBT_CONTINUE */
                                goto letscontinue;
                        }

                        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;

                if (WARN(verdict < 0, "bogus standard verdict\n")) {
                        read_unlock_bh(&table->lock);
                        return NF_DROP;
                }

                /* 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);

                if (WARN(chaininfo->distinguisher, "jump to non-chain\n")) {
                        read_unlock_bh(&table->lock);
                        return NF_DROP;
                }

                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 void ebt_free_table_info(struct ebt_table_info *info)
{
        int i;

        if (info->chainstack) {
                for_each_possible_cpu(i)
                        vfree(info->chainstack[i]);
                vfree(info->chainstack);
        }
}
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_find_match(NFPROTO_BRIDGE, m->u.name, m->u.revision);
        if (IS_ERR(match) || match->family != NFPROTO_BRIDGE) {
                if (!IS_ERR(match))
                        module_put(match->me);
                request_module("ebt_%s", m->u.name);
                match = xt_find_match(NFPROTO_BRIDGE, m->u.name, m->u.revision);
        }
        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,
              ntohs(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);

        if (watcher->family != NFPROTO_BRIDGE) {
                module_put(watcher->me);
                return -ENOENT;
        }

        w->u.watcher = watcher;

        par->target   = watcher;
        par->targinfo = w->data;
        ret = xt_check_target(par, w->watcher_size,
              ntohs(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
                                 */
                                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)
                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)))
                        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)
                        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)
                                return -EINVAL;
                }
                if (i == NF_BR_NUMHOOKS) /* it's a user defined chain */
                        (*udc_cnt)++;
                if (((struct ebt_entries *)e)->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)
                return -EINVAL;

        /* this is not checked anywhere else */
        if (e->next_offset - e->target_offset < sizeof(struct ebt_entry_target))
                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 = ebt_get_target(e);

        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)
                return -EINVAL;

        if (e->invflags & ~EBT_INV_MASK)
                return -EINVAL;

        if ((e->bitmask & EBT_NOPROTO) && (e->bitmask & EBT_802_3))
                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;

        memset(&mtpar, 0, sizeof(mtpar));
        memset(&tgpar, 0, sizeof(tgpar));
        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 = ebt_get_target(e);
        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;
        }

        /* Reject UNSPEC, xtables verdicts/return values are incompatible */
        if (target->family != NFPROTO_BRIDGE) {
                module_put(target->me);
                ret = -ENOENT;
                goto cleanup_watchers;
        }

        t->u.target = target;
        if (t->u.target == &ebt_standard_target) {
                if (gap < sizeof(struct ebt_standard_target)) {
                        ret = -EFAULT;
                        goto cleanup_watchers;
                }
                if (((struct ebt_standard_target *)t)->verdict <
                   -NUM_STANDARD_TARGETS) {
                        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,
              ntohs(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 = ebt_get_target_c(e);
                if (strcmp(t->u.name, EBT_STANDARD_TARGET))
                        goto letscontinue;
                if (e->target_offset + sizeof(struct ebt_standard_target) >
                   e->next_offset)
                        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)
                                return -1;

                        if (cl_s[i].cs.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)
                return -EINVAL;

        if (newinfo->hook_entry[i] != (struct ebt_entries *)newinfo->entries)
                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])
                        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)
                return -EINVAL;

        if (k != newinfo->nentries)
                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(array_size(nr_cpu_ids,
                                           sizeof(*(newinfo->chainstack))));
                if (!newinfo->chainstack)
                        return -ENOMEM;
                for_each_possible_cpu(i) {
                        newinfo->chainstack[i] =
                          vmalloc(array_size(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(array_size(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) {
                        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++)
                        ADD_COUNTER(counters[i], counter_base[i].pcnt,
                                    counter_base[i].bcnt);
        }
}

static int do_replace_finish(struct net *net, struct ebt_replace *repl,
                              struct ebt_table_info *newinfo)
{
        int ret;
        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) {
                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);
        ebt_free_table_info(table);
        vfree(table);
        vfree(counterstmp);

#ifdef CONFIG_AUDIT
        if (audit_enabled) {
                audit_log(audit_context(), GFP_KERNEL,
                          AUDIT_NETFILTER_CFG,
                          "table=%s family=%u entries=%u",
                          repl->name, AF_BRIDGE, repl->nentries);
        }
#endif
        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() */
        ebt_free_table_info(newinfo);
        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)
                return -EINVAL;

        if (tmp.entries_size == 0)
                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, GFP_KERNEL_ACCOUNT,
                            PAGE_KERNEL);
        if (!newinfo)
                return -ENOMEM;

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

        newinfo->entries = __vmalloc(tmp.entries_size, GFP_KERNEL_ACCOUNT,
                                     PAGE_KERNEL);
        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;
        }

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

static void __ebt_unregister_table(struct net *net, struct ebt_table *table)
{
        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);
        ebt_free_table_info(table->private);
        vfree(table->private);
        kfree(table);
}

int ebt_register_table(struct net *net, const struct ebt_table *input_table,
                       const struct nf_hook_ops *ops, struct ebt_table **res)
{
        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)
                return -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)
                goto free_chainstack;

        if (table->check && table->check(newinfo, table->valid_hooks)) {
                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;
                        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);

        WRITE_ONCE(*res, table);
        ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
        if (ret) {
                __ebt_unregister_table(net, table);
                *res = NULL;
        }

        return ret;
free_unlock:
        mutex_unlock(&ebt_mutex);
free_chainstack:
        ebt_free_table_info(newinfo);
        vfree(newinfo->entries);
free_newinfo:
        vfree(newinfo);
free_table:
        kfree(table);
out:
        return ret;
}

void ebt_unregister_table(struct net *net, struct ebt_table *table,
                          const struct nf_hook_ops *ops)
{
        nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
        __ebt_unregister_table(net, 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(array_size(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) {
                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++)
                ADD_COUNTER(t->private->counters[i], tmp[i].pcnt, 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_obj_to_user(char __user *um, const char *_name,
                                  const char *data, int entrysize,
                                  int usersize, int datasize, u8 revision)
{
        char name[EBT_EXTENSION_MAXNAMELEN] = {0};

        /* ebtables expects 31 bytes long names but xt_match names are 29 bytes
         * long. Copy 29 bytes and fill remaining bytes with zeroes.
         */
        strlcpy(name, _name, sizeof(name));
        if (copy_to_user(um, name, EBT_EXTENSION_MAXNAMELEN) ||
            put_user(revision, (u8 __user *)(um + EBT_EXTENSION_MAXNAMELEN)) ||
            put_user(datasize, (int __user *)(um + EBT_EXTENSION_MAXNAMELEN + 1)) ||
            xt_data_to_user(um + entrysize, data, usersize, datasize,
                            XT_ALIGN(datasize)))
                return -EFAULT;

        return 0;
}

static inline int ebt_match_to_user(const struct ebt_entry_match *m,
                                    const char *base, char __user *ubase)
{
        return ebt_obj_to_user(ubase + ((char *)m - base),
                               m->u.match->name, m->data, sizeof(*m),
                               m->u.match->usersize, m->match_size,
                               m->u.match->revision);
}

static inline int ebt_watcher_to_user(const struct ebt_entry_watcher *w,
                                      const char *base, char __user *ubase)
{
        return ebt_obj_to_user(ubase + ((char *)w - base),
                               w->u.watcher->name, w->data, sizeof(*w),
                               w->u.watcher->usersize, w->watcher_size,
                               w->u.watcher->revision);
}

static inline int ebt_entry_to_user(struct ebt_entry *e, const char *base,
                                    char __user *ubase)
{
        int ret;
        char __user *hlp;
        const struct ebt_entry_target *t;

        if (e->bitmask == 0) {
                /* special case !EBT_ENTRY_OR_ENTRIES */
                if (copy_to_user(ubase + ((char *)e - base), e,
                                 sizeof(struct ebt_entries)))
                        return -EFAULT;
                return 0;
        }

        if (copy_to_user(ubase + ((char *)e - base), e, sizeof(*e)))
                return -EFAULT;

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

        ret = EBT_MATCH_ITERATE(e, ebt_match_to_user, base, ubase);
        if (ret != 0)
                return ret;
        ret = EBT_WATCHER_ITERATE(e, ebt_watcher_to_user, base, ubase);
        if (ret != 0)
                return ret;
        ret = ebt_obj_to_user(hlp, t->u.target->name, t->data, sizeof(*t),
                              t->u.target->usersize, t->target_size,
                              t->u.target->revision);
        if (ret != 0)
                return ret;

        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)
                return -EINVAL;

        counterstmp = vmalloc(array_size(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)
                return -EINVAL;

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

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

        /* set the match/watcher/target names right */
        return EBT_ENTRY_ITERATE(entries, entries_size,
           ebt_entry_to_user, 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;

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

        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) {
                        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 {
                struct {
                        char name[EBT_EXTENSION_MAXNAMELEN];
                        u8 revision;
                };
                compat_uptr_t ptr;
        } u;
        compat_uint_t match_size;
        compat_uint_t data[0] __attribute__ ((aligned (__alignof__(struct compat_ebt_replace))));
};

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

        if (WARN_ON(off >= m->match_size))
                return -EINVAL;

        if (copy_to_user(cm->u.name, match->name, strlen(match->name) + 1) ||
            put_user(match->revision, &cm->u.revision) ||
            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 (xt_data_to_user(cm->data, m->data, match->usersize, msize,
                                    COMPAT_XT_ALIGN(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;

        if (WARN_ON(off >= t->target_size))
                return -EINVAL;

        if (copy_to_user(cm->u.name, target->name, strlen(target->name) + 1) ||
            put_user(target->revision, &cm->u.revision) ||
            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 (xt_data_to_user(cm->data, t->data, target->usersize, tsize,
                                    COMPAT_XT_ALIGN(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 = *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 = ebt_get_target(e);

        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 = ebt_get_target_c(e);

        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 ebt_compat_init_offsets(unsigned int number)
{
        if (number > INT_MAX)
                return -EINVAL;

        /* also count the base chain policies */
        number += NF_BR_NUMHOOKS;

        return xt_compat_init_offsets(NFPROTO_BRIDGE, number);
}

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;
        int ret;

        newinfo->entries_size = size;
        ret = ebt_compat_init_offsets(info->nentries);
        if (ret)
                return ret;

        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;

        if (WARN_ON(state->buf_kern_offset + sz > state->buf_kern_len))
                return -EINVAL;

        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;

        if (WARN_ON(b && state->buf_kern_offset > state->buf_kern_len))
                return -EINVAL;

        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_EXTENSION_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;

        if (strscpy(name, mwt->u.name, sizeof(name)) < 0)
                return -EINVAL;

        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,
                                              mwt->u.revision);
                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,
                                            mwt->u.revision);
                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) {
                if (WARN_ON(state->buf_kern_len <= pad))
                        return -EINVAL;
                if (WARN_ON(state->buf_kern_offset - (match_size + off) + size_kern > state->buf_kern_len - pad))
                        return -EINVAL;
                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;

                if (WARN_ON(ret < match32->match_size))
                        return -EINVAL;
                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;

                /* rule should have no remaining data after target */
                if (type == EBT_COMPAT_TARGET && size_left)
                        return -EINVAL;

                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; i < 4 ; ++i) {
                if (offsets[i] > *total)
                        return -EINVAL;

                if (i < 3 && offsets[i] == *total)
                        return -EINVAL;

                if (i == 0)
                        continue;
                if (offsets[i-1] > offsets[i])
                        return -EINVAL;
        }

        for (i = 0, j = 1 ; j < 4 ; j++, i++) {
                struct compat_ebt_entry_mwt *match32;
                unsigned int size;
                char *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;

        if (WARN_ON(*total < startoff))
                return -EINVAL;
        *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;

        if (size_remaining)
                return -EINVAL;

        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);

        ret = ebt_compat_init_offsets(tmp.nentries);
        if (ret < 0)
                goto out_unlock;

        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);
        if (WARN_ON(ret < 0)) {
                vfree(entries_tmp);
                goto out_unlock;
        }

        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;

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

        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;
        }

        return 0;
}

static void __exit ebtables_fini(void)
{
        nf_unregister_sockopt(&ebt_sockopts);
        xt_unregister_target(&ebt_standard_target);
}

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");