arp_tables.c

Go to the documentation of this file.

/*
 * Packet matching code for ARP packets.
 *
 * Based heavily, if not almost entirely, upon ip_tables.c framework.
 *
 * Some ARP specific bits are:
 *
 * Copyright (C) 2002 David S. Miller ([email protected])
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/capability.h>
#include <linux/if_arp.h>
#include <linux/kmod.h>
#include <linux/vmalloc.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <net/compat.h>
#include <net/sock.h>
#include <asm/uaccess.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_arp/arp_tables.h>
#include "../../netfilter/xt_repldata.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David S. Miller <[email protected]>");
MODULE_DESCRIPTION("arptables core");

/*#define DEBUG_ARP_TABLES*/
/*#define DEBUG_ARP_TABLES_USER*/

#ifdef DEBUG_ARP_TABLES
#define dprintf(format, args...)  printk(format , ## args)
#else
#define dprintf(format, args...)
#endif

#ifdef DEBUG_ARP_TABLES_USER
#define duprintf(format, args...) printk(format , ## args)
#else
#define duprintf(format, args...)
#endif

#ifdef CONFIG_NETFILTER_DEBUG
#define ARP_NF_ASSERT(x)    WARN_ON(!(x))
#else
#define ARP_NF_ASSERT(x)
#endif

void *arpt_alloc_initial_table(const struct xt_table *info)
{
    return xt_alloc_initial_table(arpt, ARPT);
}
EXPORT_SYMBOL_GPL(arpt_alloc_initial_table);

static inline int arp_devaddr_compare(const struct arpt_devaddr_info *ap,
                      const char *hdr_addr, int len)
{
    int i, ret;

    if (len > ARPT_DEV_ADDR_LEN_MAX)
        len = ARPT_DEV_ADDR_LEN_MAX;

    ret = 0;
    for (i = 0; i < len; i++)
        ret |= (hdr_addr[i] ^ ap->addr[i]) & ap->mask[i];

    return ret != 0;
}

/*
 * Unfortunately, _b and _mask are not aligned to an int (or long int)
 * Some arches dont care, unrolling the loop is a win on them.
 * For other arches, we only have a 16bit alignement.
 */
static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
{
#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
    unsigned long ret = ifname_compare_aligned(_a, _b, _mask);
#else
    unsigned long ret = 0;
    const u16 *a = (const u16 *)_a;
    const u16 *b = (const u16 *)_b;
    const u16 *mask = (const u16 *)_mask;
    int i;

    for (i = 0; i < IFNAMSIZ/sizeof(u16); i++)
        ret |= (a[i] ^ b[i]) & mask[i];
#endif
    return ret;
}

/* Returns whether packet matches rule or not. */
static inline int arp_packet_match(const struct arphdr *arphdr,
                   struct net_device *dev,
                   const char *indev,
                   const char *outdev,
                   const struct arpt_arp *arpinfo)
{
    const char *arpptr = (char *)(arphdr + 1);
    const char *src_devaddr, *tgt_devaddr;
    __be32 src_ipaddr, tgt_ipaddr;
    long ret;

#define FWINV(bool, invflg) ((bool) ^ !!(arpinfo->invflags & (invflg)))

    if (FWINV((arphdr->ar_op & arpinfo->arpop_mask) != arpinfo->arpop,
          ARPT_INV_ARPOP)) {
        dprintf("ARP operation field mismatch.\n");
        dprintf("ar_op: %04x info->arpop: %04x info->arpop_mask: %04x\n",
            arphdr->ar_op, arpinfo->arpop, arpinfo->arpop_mask);
        return 0;
    }

    if (FWINV((arphdr->ar_hrd & arpinfo->arhrd_mask) != arpinfo->arhrd,
          ARPT_INV_ARPHRD)) {
        dprintf("ARP hardware address format mismatch.\n");
        dprintf("ar_hrd: %04x info->arhrd: %04x info->arhrd_mask: %04x\n",
            arphdr->ar_hrd, arpinfo->arhrd, arpinfo->arhrd_mask);
        return 0;
    }

    if (FWINV((arphdr->ar_pro & arpinfo->arpro_mask) != arpinfo->arpro,
          ARPT_INV_ARPPRO)) {
        dprintf("ARP protocol address format mismatch.\n");
        dprintf("ar_pro: %04x info->arpro: %04x info->arpro_mask: %04x\n",
            arphdr->ar_pro, arpinfo->arpro, arpinfo->arpro_mask);
        return 0;
    }

    if (FWINV((arphdr->ar_hln & arpinfo->arhln_mask) != arpinfo->arhln,
          ARPT_INV_ARPHLN)) {
        dprintf("ARP hardware address length mismatch.\n");
        dprintf("ar_hln: %02x info->arhln: %02x info->arhln_mask: %02x\n",
            arphdr->ar_hln, arpinfo->arhln, arpinfo->arhln_mask);
        return 0;
    }

    src_devaddr = arpptr;
    arpptr += dev->addr_len;
    memcpy(&src_ipaddr, arpptr, sizeof(u32));
    arpptr += sizeof(u32);
    tgt_devaddr = arpptr;
    arpptr += dev->addr_len;
    memcpy(&tgt_ipaddr, arpptr, sizeof(u32));

    if (FWINV(arp_devaddr_compare(&arpinfo->src_devaddr, src_devaddr, dev->addr_len),
          ARPT_INV_SRCDEVADDR) ||
        FWINV(arp_devaddr_compare(&arpinfo->tgt_devaddr, tgt_devaddr, dev->addr_len),
          ARPT_INV_TGTDEVADDR)) {
        dprintf("Source or target device address mismatch.\n");

        return 0;
    }

    if (FWINV((src_ipaddr & arpinfo->smsk.s_addr) != arpinfo->src.s_addr,
          ARPT_INV_SRCIP) ||
        FWINV(((tgt_ipaddr & arpinfo->tmsk.s_addr) != arpinfo->tgt.s_addr),
          ARPT_INV_TGTIP)) {
        dprintf("Source or target IP address mismatch.\n");

        dprintf("SRC: %pI4. Mask: %pI4. Target: %pI4.%s\n",
            &src_ipaddr,
            &arpinfo->smsk.s_addr,
            &arpinfo->src.s_addr,
            arpinfo->invflags & ARPT_INV_SRCIP ? " (INV)" : "");
        dprintf("TGT: %pI4 Mask: %pI4 Target: %pI4.%s\n",
            &tgt_ipaddr,
            &arpinfo->tmsk.s_addr,
            &arpinfo->tgt.s_addr,
            arpinfo->invflags & ARPT_INV_TGTIP ? " (INV)" : "");
        return 0;
    }

    /* Look for ifname matches.  */
    ret = ifname_compare(indev, arpinfo->iniface, arpinfo->iniface_mask);

    if (FWINV(ret != 0, ARPT_INV_VIA_IN)) {
        dprintf("VIA in mismatch (%s vs %s).%s\n",
            indev, arpinfo->iniface,
            arpinfo->invflags&ARPT_INV_VIA_IN ?" (INV)":"");
        return 0;
    }

    ret = ifname_compare(outdev, arpinfo->outiface, arpinfo->outiface_mask);

    if (FWINV(ret != 0, ARPT_INV_VIA_OUT)) {
        dprintf("VIA out mismatch (%s vs %s).%s\n",
            outdev, arpinfo->outiface,
            arpinfo->invflags&ARPT_INV_VIA_OUT ?" (INV)":"");
        return 0;
    }

    return 1;
#undef FWINV
}

static inline int arp_checkentry(const struct arpt_arp *arp)
{
    if (arp->flags & ~ARPT_F_MASK) {
        duprintf("Unknown flag bits set: %08X\n",
             arp->flags & ~ARPT_F_MASK);
        return 0;
    }
    if (arp->invflags & ~ARPT_INV_MASK) {
        duprintf("Unknown invflag bits set: %08X\n",
             arp->invflags & ~ARPT_INV_MASK);
        return 0;
    }

    return 1;
}

static unsigned int
arpt_error(struct sk_buff *skb, const struct xt_action_param *par)
{
    net_err_ratelimited("arp_tables: error: '%s'\n",
                (const char *)par->targinfo);

    return NF_DROP;
}

static inline const struct xt_entry_target *
arpt_get_target_c(const struct arpt_entry *e)
{
    return arpt_get_target((struct arpt_entry *)e);
}

static inline struct arpt_entry *
get_entry(const void *base, unsigned int offset)
{
    return (struct arpt_entry *)(base + offset);
}

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

unsigned int arpt_do_table(struct sk_buff *skb,
               unsigned int hook,
               const struct net_device *in,
               const struct net_device *out,
               struct xt_table *table)
{
    static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
    unsigned int verdict = NF_DROP;
    const struct arphdr *arp;
    struct arpt_entry *e, *back;
    const char *indev, *outdev;
    void *table_base;
    const struct xt_table_info *private;
    struct xt_action_param acpar;
    unsigned int addend;

    if (!pskb_may_pull(skb, arp_hdr_len(skb->dev)))
        return NF_DROP;

    indev = in ? in->name : nulldevname;
    outdev = out ? out->name : nulldevname;

    local_bh_disable();
    addend = xt_write_recseq_begin();
    private = table->private;
    table_base = private->entries[smp_processor_id()];

    e = get_entry(table_base, private->hook_entry[hook]);
    back = get_entry(table_base, private->underflow[hook]);

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

    arp = arp_hdr(skb);
    do {
        const struct xt_entry_target *t;

        if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
            e = arpt_next_entry(e);
            continue;
        }

        ADD_COUNTER(e->counters, arp_hdr_len(skb->dev), 1);

        t = arpt_get_target_c(e);

        /* Standard target? */
        if (!t->u.kernel.target->target) {
            int v;

            v = ((struct xt_standard_target *)t)->verdict;
            if (v < 0) {
                /* Pop from stack? */
                if (v != XT_RETURN) {
                    verdict = (unsigned int)(-v) - 1;
                    break;
                }
                e = back;
                back = get_entry(table_base, back->comefrom);
                continue;
            }
            if (table_base + v
                != arpt_next_entry(e)) {
                /* Save old back ptr in next entry */
                struct arpt_entry *next = arpt_next_entry(e);
                next->comefrom = (void *)back - table_base;

                /* set back pointer to next entry */
                back = next;
            }

            e = get_entry(table_base, v);
            continue;
        }

        /* Targets which reenter must return
         * abs. verdicts
         */
        acpar.target   = t->u.kernel.target;
        acpar.targinfo = t->data;
        verdict = t->u.kernel.target->target(skb, &acpar);

        /* Target might have changed stuff. */
        arp = arp_hdr(skb);

        if (verdict == XT_CONTINUE)
            e = arpt_next_entry(e);
        else
            /* Verdict */
            break;
    } while (!acpar.hotdrop);
    xt_write_recseq_end(addend);
    local_bh_enable();

    if (acpar.hotdrop)
        return NF_DROP;
    else
        return verdict;
}

/* All zeroes == unconditional rule. */
static inline bool unconditional(const struct arpt_arp *arp)
{
    static const struct arpt_arp uncond;

    return memcmp(arp, &uncond, sizeof(uncond)) == 0;
}

/* Figures out from what hook each rule can be called: returns 0 if
 * there are loops.  Puts hook bitmask in comefrom.
 */
static int mark_source_chains(const struct xt_table_info *newinfo,
                  unsigned int valid_hooks, void *entry0)
{
    unsigned int hook;

    /* No recursion; use packet counter to save back ptrs (reset
     * to 0 as we leave), and comefrom to save source hook bitmask.
     */
    for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
        unsigned int pos = newinfo->hook_entry[hook];
        struct arpt_entry *e
            = (struct arpt_entry *)(entry0 + pos);

        if (!(valid_hooks & (1 << hook)))
            continue;

        /* Set initial back pointer. */
        e->counters.pcnt = pos;

        for (;;) {
            const struct xt_standard_target *t
                = (void *)arpt_get_target_c(e);
            int visited = e->comefrom & (1 << hook);

            if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
                pr_notice("arptables: loop hook %u pos %u %08X.\n",
                       hook, pos, e->comefrom);
                return 0;
            }
            e->comefrom
                |= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));

            /* Unconditional return/END. */
            if ((e->target_offset == sizeof(struct arpt_entry) &&
                 (strcmp(t->target.u.user.name,
                     XT_STANDARD_TARGET) == 0) &&
                 t->verdict < 0 && unconditional(&e->arp)) ||
                visited) {
                unsigned int oldpos, size;

                if ((strcmp(t->target.u.user.name,
                        XT_STANDARD_TARGET) == 0) &&
                    t->verdict < -NF_MAX_VERDICT - 1) {
                    duprintf("mark_source_chains: bad "
                        "negative verdict (%i)\n",
                                t->verdict);
                    return 0;
                }

                /* Return: backtrack through the last
                 * big jump.
                 */
                do {
                    e->comefrom ^= (1<<NF_ARP_NUMHOOKS);
                    oldpos = pos;
                    pos = e->counters.pcnt;
                    e->counters.pcnt = 0;

                    /* We're at the start. */
                    if (pos == oldpos)
                        goto next;

                    e = (struct arpt_entry *)
                        (entry0 + pos);
                } while (oldpos == pos + e->next_offset);

                /* Move along one */
                size = e->next_offset;
                e = (struct arpt_entry *)
                    (entry0 + pos + size);
                e->counters.pcnt = pos;
                pos += size;
            } else {
                int newpos = t->verdict;

                if (strcmp(t->target.u.user.name,
                       XT_STANDARD_TARGET) == 0 &&
                    newpos >= 0) {
                    if (newpos > newinfo->size -
                        sizeof(struct arpt_entry)) {
                        duprintf("mark_source_chains: "
                            "bad verdict (%i)\n",
                                newpos);
                        return 0;
                    }

                    /* This a jump; chase it. */
                    duprintf("Jump rule %u -> %u\n",
                         pos, newpos);
                } else {
                    /* ... this is a fallthru */
                    newpos = pos + e->next_offset;
                }
                e = (struct arpt_entry *)
                    (entry0 + newpos);
                e->counters.pcnt = pos;
                pos = newpos;
            }
        }
        next:
        duprintf("Finished chain %u\n", hook);
    }
    return 1;
}

static inline int check_entry(const struct arpt_entry *e, const char *name)
{
    const struct xt_entry_target *t;

    if (!arp_checkentry(&e->arp)) {
        duprintf("arp_tables: arp check failed %p %s.\n", e, name);
        return -EINVAL;
    }

    if (e->target_offset + sizeof(struct xt_entry_target) > e->next_offset)
        return -EINVAL;

    t = arpt_get_target_c(e);
    if (e->target_offset + t->u.target_size > e->next_offset)
        return -EINVAL;

    return 0;
}

static inline int check_target(struct arpt_entry *e, const char *name)
{
    struct xt_entry_target *t = arpt_get_target(e);
    int ret;
    struct xt_tgchk_param par = {
        .table     = name,
        .entryinfo = e,
        .target    = t->u.kernel.target,
        .targinfo  = t->data,
        .hook_mask = e->comefrom,
        .family    = NFPROTO_ARP,
    };

    ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
    if (ret < 0) {
        duprintf("arp_tables: check failed for `%s'.\n",
             t->u.kernel.target->name);
        return ret;
    }
    return 0;
}

static inline int
find_check_entry(struct arpt_entry *e, const char *name, unsigned int size)
{
    struct xt_entry_target *t;
    struct xt_target *target;
    int ret;

    ret = check_entry(e, name);
    if (ret)
        return ret;

    t = arpt_get_target(e);
    target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
                    t->u.user.revision);
    if (IS_ERR(target)) {
        duprintf("find_check_entry: `%s' not found\n", t->u.user.name);
        ret = PTR_ERR(target);
        goto out;
    }
    t->u.kernel.target = target;

    ret = check_target(e, name);
    if (ret)
        goto err;
    return 0;
err:
    module_put(t->u.kernel.target->me);
out:
    return ret;
}

static bool check_underflow(const struct arpt_entry *e)
{
    const struct xt_entry_target *t;
    unsigned int verdict;

    if (!unconditional(&e->arp))
        return false;
    t = arpt_get_target_c(e);
    if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
        return false;
    verdict = ((struct xt_standard_target *)t)->verdict;
    verdict = -verdict - 1;
    return verdict == NF_DROP || verdict == NF_ACCEPT;
}

static inline int check_entry_size_and_hooks(struct arpt_entry *e,
                         struct xt_table_info *newinfo,
                         const unsigned char *base,
                         const unsigned char *limit,
                         const unsigned int *hook_entries,
                         const unsigned int *underflows,
                         unsigned int valid_hooks)
{
    unsigned int h;

    if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
        (unsigned char *)e + sizeof(struct arpt_entry) >= limit) {
        duprintf("Bad offset %p\n", e);
        return -EINVAL;
    }

    if (e->next_offset
        < sizeof(struct arpt_entry) + sizeof(struct xt_entry_target)) {
        duprintf("checking: element %p size %u\n",
             e, e->next_offset);
        return -EINVAL;
    }

    /* Check hooks & underflows */
    for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
        if (!(valid_hooks & (1 << h)))
            continue;
        if ((unsigned char *)e - base == hook_entries[h])
            newinfo->hook_entry[h] = hook_entries[h];
        if ((unsigned char *)e - base == underflows[h]) {
            if (!check_underflow(e)) {
                pr_err("Underflows must be unconditional and "
                       "use the STANDARD target with "
                       "ACCEPT/DROP\n");
                return -EINVAL;
            }
            newinfo->underflow[h] = underflows[h];
        }
    }

    /* Clear counters and comefrom */
    e->counters = ((struct xt_counters) { 0, 0 });
    e->comefrom = 0;
    return 0;
}

static inline void cleanup_entry(struct arpt_entry *e)
{
    struct xt_tgdtor_param par;
    struct xt_entry_target *t;

    t = arpt_get_target(e);
    par.target   = t->u.kernel.target;
    par.targinfo = t->data;
    par.family   = NFPROTO_ARP;
    if (par.target->destroy != NULL)
        par.target->destroy(&par);
    module_put(par.target->me);
}

/* Checks and translates the user-supplied table segment (held in
 * newinfo).
 */
static int translate_table(struct xt_table_info *newinfo, void *entry0,
                           const struct arpt_replace *repl)
{
    struct arpt_entry *iter;
    unsigned int i;
    int ret = 0;

    newinfo->size = repl->size;
    newinfo->number = repl->num_entries;

    /* Init all hooks to impossible value. */
    for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
        newinfo->hook_entry[i] = 0xFFFFFFFF;
        newinfo->underflow[i] = 0xFFFFFFFF;
    }

    duprintf("translate_table: size %u\n", newinfo->size);
    i = 0;

    /* Walk through entries, checking offsets. */
    xt_entry_foreach(iter, entry0, newinfo->size) {
        ret = check_entry_size_and_hooks(iter, newinfo, entry0,
                         entry0 + repl->size,
                         repl->hook_entry,
                         repl->underflow,
                         repl->valid_hooks);
        if (ret != 0)
            break;
        ++i;
        if (strcmp(arpt_get_target(iter)->u.user.name,
            XT_ERROR_TARGET) == 0)
            ++newinfo->stacksize;
    }
    duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret);
    if (ret != 0)
        return ret;

    if (i != repl->num_entries) {
        duprintf("translate_table: %u not %u entries\n",
             i, repl->num_entries);
        return -EINVAL;
    }

    /* Check hooks all assigned */
    for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
        /* Only hooks which are valid */
        if (!(repl->valid_hooks & (1 << i)))
            continue;
        if (newinfo->hook_entry[i] == 0xFFFFFFFF) {
            duprintf("Invalid hook entry %u %u\n",
                 i, repl->hook_entry[i]);
            return -EINVAL;
        }
        if (newinfo->underflow[i] == 0xFFFFFFFF) {
            duprintf("Invalid underflow %u %u\n",
                 i, repl->underflow[i]);
            return -EINVAL;
        }
    }

    if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) {
        duprintf("Looping hook\n");
        return -ELOOP;
    }

    /* Finally, each sanity check must pass */
    i = 0;
    xt_entry_foreach(iter, entry0, newinfo->size) {
        ret = find_check_entry(iter, repl->name, repl->size);
        if (ret != 0)
            break;
        ++i;
    }

    if (ret != 0) {
        xt_entry_foreach(iter, entry0, newinfo->size) {
            if (i-- == 0)
                break;
            cleanup_entry(iter);
        }
        return ret;
    }

    /* And one copy for every other CPU */
    for_each_possible_cpu(i) {
        if (newinfo->entries[i] && newinfo->entries[i] != entry0)
            memcpy(newinfo->entries[i], entry0, newinfo->size);
    }

    return ret;
}

static void get_counters(const struct xt_table_info *t,
             struct xt_counters counters[])
{
    struct arpt_entry *iter;
    unsigned int cpu;
    unsigned int i;

    for_each_possible_cpu(cpu) {
        seqcount_t *s = &per_cpu(xt_recseq, cpu);

        i = 0;
        xt_entry_foreach(iter, t->entries[cpu], t->size) {
            u64 bcnt, pcnt;
            unsigned int start;

            do {
                start = read_seqcount_begin(s);
                bcnt = iter->counters.bcnt;
                pcnt = iter->counters.pcnt;
            } while (read_seqcount_retry(s, start));

            ADD_COUNTER(counters[i], bcnt, pcnt);
            ++i;
        }
    }
}

static struct xt_counters *alloc_counters(const struct xt_table *table)
{
    unsigned int countersize;
    struct xt_counters *counters;
    const struct xt_table_info *private = table->private;

    /* We need atomic snapshot of counters: rest doesn't change
     * (other than comefrom, which userspace doesn't care
     * about).
     */
    countersize = sizeof(struct xt_counters) * private->number;
    counters = vzalloc(countersize);

    if (counters == NULL)
        return ERR_PTR(-ENOMEM);

    get_counters(private, counters);

    return counters;
}

static int copy_entries_to_user(unsigned int total_size,
                const struct xt_table *table,
                void __user *userptr)
{
    unsigned int off, num;
    const struct arpt_entry *e;
    struct xt_counters *counters;
    struct xt_table_info *private = table->private;
    int ret = 0;
    void *loc_cpu_entry;

    counters = alloc_counters(table);
    if (IS_ERR(counters))
        return PTR_ERR(counters);

    loc_cpu_entry = private->entries[raw_smp_processor_id()];
    /* ... then copy entire thing ... */
    if (copy_to_user(userptr, loc_cpu_entry, total_size) != 0) {
        ret = -EFAULT;
        goto free_counters;
    }

    /* FIXME: use iterator macros --RR */
    /* ... then go back and fix counters and names */
    for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
        const struct xt_entry_target *t;

        e = (struct arpt_entry *)(loc_cpu_entry + off);
        if (copy_to_user(userptr + off
                 + offsetof(struct arpt_entry, counters),
                 &counters[num],
                 sizeof(counters[num])) != 0) {
            ret = -EFAULT;
            goto free_counters;
        }

        t = arpt_get_target_c(e);
        if (copy_to_user(userptr + off + e->target_offset
                 + offsetof(struct xt_entry_target,
                        u.user.name),
                 t->u.kernel.target->name,
                 strlen(t->u.kernel.target->name)+1) != 0) {
            ret = -EFAULT;
            goto free_counters;
        }
    }

 free_counters:
    vfree(counters);
    return ret;
}

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

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

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

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

static int compat_calc_entry(const struct arpt_entry *e,
                 const struct xt_table_info *info,
                 const void *base, struct xt_table_info *newinfo)
{
    const struct xt_entry_target *t;
    unsigned int entry_offset;
    int off, i, ret;

    off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
    entry_offset = (void *)e - base;

    t = arpt_get_target_c(e);
    off += xt_compat_target_offset(t->u.kernel.target);
    newinfo->size -= off;
    ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
    if (ret)
        return ret;

    for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
        if (info->hook_entry[i] &&
            (e < (struct arpt_entry *)(base + info->hook_entry[i])))
            newinfo->hook_entry[i] -= off;
        if (info->underflow[i] &&
            (e < (struct arpt_entry *)(base + info->underflow[i])))
            newinfo->underflow[i] -= off;
    }
    return 0;
}

static int compat_table_info(const struct xt_table_info *info,
                 struct xt_table_info *newinfo)
{
    struct arpt_entry *iter;
    void *loc_cpu_entry;
    int ret;

    if (!newinfo || !info)
        return -EINVAL;

    /* we dont care about newinfo->entries[] */
    memcpy(newinfo, info, offsetof(struct xt_table_info, entries));
    newinfo->initial_entries = 0;
    loc_cpu_entry = info->entries[raw_smp_processor_id()];
    xt_compat_init_offsets(NFPROTO_ARP, info->number);
    xt_entry_foreach(iter, loc_cpu_entry, info->size) {
        ret = compat_calc_entry(iter, info, loc_cpu_entry, newinfo);
        if (ret != 0)
            return ret;
    }
    return 0;
}
#endif

static int get_info(struct net *net, void __user *user,
                    const int *len, int compat)
{
    char name[XT_TABLE_MAXNAMELEN];
    struct xt_table *t;
    int ret;

    if (*len != sizeof(struct arpt_getinfo)) {
        duprintf("length %u != %Zu\n", *len,
             sizeof(struct arpt_getinfo));
        return -EINVAL;
    }

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

    name[XT_TABLE_MAXNAMELEN-1] = '\0';
#ifdef CONFIG_COMPAT
    if (compat)
        xt_compat_lock(NFPROTO_ARP);
#endif
    t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
                    "arptable_%s", name);
    if (t && !IS_ERR(t)) {
        struct arpt_getinfo info;
        const struct xt_table_info *private = t->private;
#ifdef CONFIG_COMPAT
        struct xt_table_info tmp;

        if (compat) {
            ret = compat_table_info(private, &tmp);
            xt_compat_flush_offsets(NFPROTO_ARP);
            private = &tmp;
        }
#endif
        memset(&info, 0, sizeof(info));
        info.valid_hooks = t->valid_hooks;
        memcpy(info.hook_entry, private->hook_entry,
               sizeof(info.hook_entry));
        memcpy(info.underflow, private->underflow,
               sizeof(info.underflow));
        info.num_entries = private->number;
        info.size = private->size;
        strcpy(info.name, name);

        if (copy_to_user(user, &info, *len) != 0)
            ret = -EFAULT;
        else
            ret = 0;
        xt_table_unlock(t);
        module_put(t->me);
    } else
        ret = t ? PTR_ERR(t) : -ENOENT;
#ifdef CONFIG_COMPAT
    if (compat)
        xt_compat_unlock(NFPROTO_ARP);
#endif
    return ret;
}

static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
               const int *len)
{
    int ret;
    struct arpt_get_entries get;
    struct xt_table *t;

    if (*len < sizeof(get)) {
        duprintf("get_entries: %u < %Zu\n", *len, sizeof(get));
        return -EINVAL;
    }
    if (copy_from_user(&get, uptr, sizeof(get)) != 0)
        return -EFAULT;
    if (*len != sizeof(struct arpt_get_entries) + get.size) {
        duprintf("get_entries: %u != %Zu\n", *len,
             sizeof(struct arpt_get_entries) + get.size);
        return -EINVAL;
    }

    t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
    if (t && !IS_ERR(t)) {
        const struct xt_table_info *private = t->private;

        duprintf("t->private->number = %u\n",
             private->number);
        if (get.size == private->size)
            ret = copy_entries_to_user(private->size,
                           t, uptr->entrytable);
        else {
            duprintf("get_entries: I've got %u not %u!\n",
                 private->size, get.size);
            ret = -EAGAIN;
        }
        module_put(t->me);
        xt_table_unlock(t);
    } else
        ret = t ? PTR_ERR(t) : -ENOENT;

    return ret;
}

static int __do_replace(struct net *net, const char *name,
            unsigned int valid_hooks,
            struct xt_table_info *newinfo,
            unsigned int num_counters,
            void __user *counters_ptr)
{
    int ret;
    struct xt_table *t;
    struct xt_table_info *oldinfo;
    struct xt_counters *counters;
    void *loc_cpu_old_entry;
    struct arpt_entry *iter;

    ret = 0;
    counters = vzalloc(num_counters * sizeof(struct xt_counters));
    if (!counters) {
        ret = -ENOMEM;
        goto out;
    }

    t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
                    "arptable_%s", name);
    if (!t || IS_ERR(t)) {
        ret = t ? PTR_ERR(t) : -ENOENT;
        goto free_newinfo_counters_untrans;
    }

    /* You lied! */
    if (valid_hooks != t->valid_hooks) {
        duprintf("Valid hook crap: %08X vs %08X\n",
             valid_hooks, t->valid_hooks);
        ret = -EINVAL;
        goto put_module;
    }

    oldinfo = xt_replace_table(t, num_counters, newinfo, &ret);
    if (!oldinfo)
        goto put_module;

    /* Update module usage count based on number of rules */
    duprintf("do_replace: oldnum=%u, initnum=%u, newnum=%u\n",
        oldinfo->number, oldinfo->initial_entries, newinfo->number);
    if ((oldinfo->number > oldinfo->initial_entries) ||
        (newinfo->number <= oldinfo->initial_entries))
        module_put(t->me);
    if ((oldinfo->number > oldinfo->initial_entries) &&
        (newinfo->number <= oldinfo->initial_entries))
        module_put(t->me);

    /* Get the old counters, and synchronize with replace */
    get_counters(oldinfo, counters);

    /* Decrease module usage counts and free resource */
    loc_cpu_old_entry = oldinfo->entries[raw_smp_processor_id()];
    xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
        cleanup_entry(iter);

    xt_free_table_info(oldinfo);
    if (copy_to_user(counters_ptr, counters,
             sizeof(struct xt_counters) * num_counters) != 0)
        ret = -EFAULT;
    vfree(counters);
    xt_table_unlock(t);
    return ret;

 put_module:
    module_put(t->me);
    xt_table_unlock(t);
 free_newinfo_counters_untrans:
    vfree(counters);
 out:
    return ret;
}

static int do_replace(struct net *net, const void __user *user,
                      unsigned int len)
{
    int ret;
    struct arpt_replace tmp;
    struct xt_table_info *newinfo;
    void *loc_cpu_entry;
    struct arpt_entry *iter;

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

    /* overflow check */
    if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
        return -ENOMEM;
    tmp.name[sizeof(tmp.name)-1] = 0;

    newinfo = xt_alloc_table_info(tmp.size);
    if (!newinfo)
        return -ENOMEM;

    /* choose the copy that is on our node/cpu */
    loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
    if (copy_from_user(loc_cpu_entry, user + sizeof(tmp),
               tmp.size) != 0) {
        ret = -EFAULT;
        goto free_newinfo;
    }

    ret = translate_table(newinfo, loc_cpu_entry, &tmp);
    if (ret != 0)
        goto free_newinfo;

    duprintf("arp_tables: Translated table\n");

    ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
               tmp.num_counters, tmp.counters);
    if (ret)
        goto free_newinfo_untrans;
    return 0;

 free_newinfo_untrans:
    xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
        cleanup_entry(iter);
 free_newinfo:
    xt_free_table_info(newinfo);
    return ret;
}

static int do_add_counters(struct net *net, const void __user *user,
               unsigned int len, int compat)
{
    unsigned int i, curcpu;
    struct xt_counters_info tmp;
    struct xt_counters *paddc;
    unsigned int num_counters;
    const char *name;
    int size;
    void *ptmp;
    struct xt_table *t;
    const struct xt_table_info *private;
    int ret = 0;
    void *loc_cpu_entry;
    struct arpt_entry *iter;
    unsigned int addend;
#ifdef CONFIG_COMPAT
    struct compat_xt_counters_info compat_tmp;

    if (compat) {
        ptmp = &compat_tmp;
        size = sizeof(struct compat_xt_counters_info);
    } else
#endif
    {
        ptmp = &tmp;
        size = sizeof(struct xt_counters_info);
    }

    if (copy_from_user(ptmp, user, size) != 0)
        return -EFAULT;

#ifdef CONFIG_COMPAT
    if (compat) {
        num_counters = compat_tmp.num_counters;
        name = compat_tmp.name;
    } else
#endif
    {
        num_counters = tmp.num_counters;
        name = tmp.name;
    }

    if (len != size + num_counters * sizeof(struct xt_counters))
        return -EINVAL;

    paddc = vmalloc(len - size);
    if (!paddc)
        return -ENOMEM;

    if (copy_from_user(paddc, user + size, len - size) != 0) {
        ret = -EFAULT;
        goto free;
    }

    t = xt_find_table_lock(net, NFPROTO_ARP, name);
    if (!t || IS_ERR(t)) {
        ret = t ? PTR_ERR(t) : -ENOENT;
        goto free;
    }

    local_bh_disable();
    private = t->private;
    if (private->number != num_counters) {
        ret = -EINVAL;
        goto unlock_up_free;
    }

    i = 0;
    /* Choose the copy that is on our node */
    curcpu = smp_processor_id();
    loc_cpu_entry = private->entries[curcpu];
    addend = xt_write_recseq_begin();
    xt_entry_foreach(iter, loc_cpu_entry, private->size) {
        ADD_COUNTER(iter->counters, paddc[i].bcnt, paddc[i].pcnt);
        ++i;
    }
    xt_write_recseq_end(addend);
 unlock_up_free:
    local_bh_enable();
    xt_table_unlock(t);
    module_put(t->me);
 free:
    vfree(paddc);

    return ret;
}

#ifdef CONFIG_COMPAT
static inline void compat_release_entry(struct compat_arpt_entry *e)
{
    struct xt_entry_target *t;

    t = compat_arpt_get_target(e);
    module_put(t->u.kernel.target->me);
}

static inline int
check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
                  struct xt_table_info *newinfo,
                  unsigned int *size,
                  const unsigned char *base,
                  const unsigned char *limit,
                  const unsigned int *hook_entries,
                  const unsigned int *underflows,
                  const char *name)
{
    struct xt_entry_target *t;
    struct xt_target *target;
    unsigned int entry_offset;
    int ret, off, h;

    duprintf("check_compat_entry_size_and_hooks %p\n", e);
    if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
        (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit) {
        duprintf("Bad offset %p, limit = %p\n", e, limit);
        return -EINVAL;
    }

    if (e->next_offset < sizeof(struct compat_arpt_entry) +
                 sizeof(struct compat_xt_entry_target)) {
        duprintf("checking: element %p size %u\n",
             e, e->next_offset);
        return -EINVAL;
    }

    /* For purposes of check_entry casting the compat entry is fine */
    ret = check_entry((struct arpt_entry *)e, name);
    if (ret)
        return ret;

    off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
    entry_offset = (void *)e - (void *)base;

    t = compat_arpt_get_target(e);
    target = xt_request_find_target(NFPROTO_ARP, t->u.user.name,
                    t->u.user.revision);
    if (IS_ERR(target)) {
        duprintf("check_compat_entry_size_and_hooks: `%s' not found\n",
             t->u.user.name);
        ret = PTR_ERR(target);
        goto out;
    }
    t->u.kernel.target = target;

    off += xt_compat_target_offset(target);
    *size += off;
    ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
    if (ret)
        goto release_target;

    /* Check hooks & underflows */
    for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
        if ((unsigned char *)e - base == hook_entries[h])
            newinfo->hook_entry[h] = hook_entries[h];
        if ((unsigned char *)e - base == underflows[h])
            newinfo->underflow[h] = underflows[h];
    }

    /* Clear counters and comefrom */
    memset(&e->counters, 0, sizeof(e->counters));
    e->comefrom = 0;
    return 0;

release_target:
    module_put(t->u.kernel.target->me);
out:
    return ret;
}

static int
compat_copy_entry_from_user(struct compat_arpt_entry *e, void **dstptr,
                unsigned int *size, const char *name,
                struct xt_table_info *newinfo, unsigned char *base)
{
    struct xt_entry_target *t;
    struct xt_target *target;
    struct arpt_entry *de;
    unsigned int origsize;
    int ret, h;

    ret = 0;
    origsize = *size;
    de = (struct arpt_entry *)*dstptr;
    memcpy(de, e, sizeof(struct arpt_entry));
    memcpy(&de->counters, &e->counters, sizeof(e->counters));

    *dstptr += sizeof(struct arpt_entry);
    *size += sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);

    de->target_offset = e->target_offset - (origsize - *size);
    t = compat_arpt_get_target(e);
    target = t->u.kernel.target;
    xt_compat_target_from_user(t, dstptr, size);

    de->next_offset = e->next_offset - (origsize - *size);
    for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
        if ((unsigned char *)de - base < newinfo->hook_entry[h])
            newinfo->hook_entry[h] -= origsize - *size;
        if ((unsigned char *)de - base < newinfo->underflow[h])
            newinfo->underflow[h] -= origsize - *size;
    }
    return ret;
}

static int translate_compat_table(const char *name,
                  unsigned int valid_hooks,
                  struct xt_table_info **pinfo,
                  void **pentry0,
                  unsigned int total_size,
                  unsigned int number,
                  unsigned int *hook_entries,
                  unsigned int *underflows)
{
    unsigned int i, j;
    struct xt_table_info *newinfo, *info;
    void *pos, *entry0, *entry1;
    struct compat_arpt_entry *iter0;
    struct arpt_entry *iter1;
    unsigned int size;
    int ret = 0;

    info = *pinfo;
    entry0 = *pentry0;
    size = total_size;
    info->number = number;

    /* Init all hooks to impossible value. */
    for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
        info->hook_entry[i] = 0xFFFFFFFF;
        info->underflow[i] = 0xFFFFFFFF;
    }

    duprintf("translate_compat_table: size %u\n", info->size);
    j = 0;
    xt_compat_lock(NFPROTO_ARP);
    xt_compat_init_offsets(NFPROTO_ARP, number);
    /* Walk through entries, checking offsets. */
    xt_entry_foreach(iter0, entry0, total_size) {
        ret = check_compat_entry_size_and_hooks(iter0, info, &size,
                            entry0,
                            entry0 + total_size,
                            hook_entries,
                            underflows,
                            name);
        if (ret != 0)
            goto out_unlock;
        ++j;
    }

    ret = -EINVAL;
    if (j != number) {
        duprintf("translate_compat_table: %u not %u entries\n",
             j, number);
        goto out_unlock;
    }

    /* Check hooks all assigned */
    for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
        /* Only hooks which are valid */
        if (!(valid_hooks & (1 << i)))
            continue;
        if (info->hook_entry[i] == 0xFFFFFFFF) {
            duprintf("Invalid hook entry %u %u\n",
                 i, hook_entries[i]);
            goto out_unlock;
        }
        if (info->underflow[i] == 0xFFFFFFFF) {
            duprintf("Invalid underflow %u %u\n",
                 i, underflows[i]);
            goto out_unlock;
        }
    }

    ret = -ENOMEM;
    newinfo = xt_alloc_table_info(size);
    if (!newinfo)
        goto out_unlock;

    newinfo->number = number;
    for (i = 0; i < NF_ARP_NUMHOOKS; i++) {
        newinfo->hook_entry[i] = info->hook_entry[i];
        newinfo->underflow[i] = info->underflow[i];
    }
    entry1 = newinfo->entries[raw_smp_processor_id()];
    pos = entry1;
    size = total_size;
    xt_entry_foreach(iter0, entry0, total_size) {
        ret = compat_copy_entry_from_user(iter0, &pos, &size,
                          name, newinfo, entry1);
        if (ret != 0)
            break;
    }
    xt_compat_flush_offsets(NFPROTO_ARP);
    xt_compat_unlock(NFPROTO_ARP);
    if (ret)
        goto free_newinfo;

    ret = -ELOOP;
    if (!mark_source_chains(newinfo, valid_hooks, entry1))
        goto free_newinfo;

    i = 0;
    xt_entry_foreach(iter1, entry1, newinfo->size) {
        ret = check_target(iter1, name);
        if (ret != 0)
            break;
        ++i;
        if (strcmp(arpt_get_target(iter1)->u.user.name,
            XT_ERROR_TARGET) == 0)
            ++newinfo->stacksize;
    }
    if (ret) {
        /*
         * The first i matches need cleanup_entry (calls ->destroy)
         * because they had called ->check already. The other j-i
         * entries need only release.
         */
        int skip = i;
        j -= i;
        xt_entry_foreach(iter0, entry0, newinfo->size) {
            if (skip-- > 0)
                continue;
            if (j-- == 0)
                break;
            compat_release_entry(iter0);
        }
        xt_entry_foreach(iter1, entry1, newinfo->size) {
            if (i-- == 0)
                break;
            cleanup_entry(iter1);
        }
        xt_free_table_info(newinfo);
        return ret;
    }

    /* And one copy for every other CPU */
    for_each_possible_cpu(i)
        if (newinfo->entries[i] && newinfo->entries[i] != entry1)
            memcpy(newinfo->entries[i], entry1, newinfo->size);

    *pinfo = newinfo;
    *pentry0 = entry1;
    xt_free_table_info(info);
    return 0;

free_newinfo:
    xt_free_table_info(newinfo);
out:
    xt_entry_foreach(iter0, entry0, total_size) {
        if (j-- == 0)
            break;
        compat_release_entry(iter0);
    }
    return ret;
out_unlock:
    xt_compat_flush_offsets(NFPROTO_ARP);
    xt_compat_unlock(NFPROTO_ARP);
    goto out;
}

struct compat_arpt_replace {
    char                name[XT_TABLE_MAXNAMELEN];
    u32             valid_hooks;
    u32             num_entries;
    u32             size;
    u32             hook_entry[NF_ARP_NUMHOOKS];
    u32             underflow[NF_ARP_NUMHOOKS];
    u32             num_counters;
    compat_uptr_t           counters;
    struct compat_arpt_entry    entries[0];
};

static int compat_do_replace(struct net *net, void __user *user,
                 unsigned int len)
{
    int ret;
    struct compat_arpt_replace tmp;
    struct xt_table_info *newinfo;
    void *loc_cpu_entry;
    struct arpt_entry *iter;

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

    /* overflow check */
    if (tmp.size >= INT_MAX / num_possible_cpus())
        return -ENOMEM;
    if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
        return -ENOMEM;
    tmp.name[sizeof(tmp.name)-1] = 0;

    newinfo = xt_alloc_table_info(tmp.size);
    if (!newinfo)
        return -ENOMEM;

    /* choose the copy that is on our node/cpu */
    loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
    if (copy_from_user(loc_cpu_entry, user + sizeof(tmp), tmp.size) != 0) {
        ret = -EFAULT;
        goto free_newinfo;
    }

    ret = translate_compat_table(tmp.name, tmp.valid_hooks,
                     &newinfo, &loc_cpu_entry, tmp.size,
                     tmp.num_entries, tmp.hook_entry,
                     tmp.underflow);
    if (ret != 0)
        goto free_newinfo;

    duprintf("compat_do_replace: Translated table\n");

    ret = __do_replace(net, tmp.name, tmp.valid_hooks, newinfo,
               tmp.num_counters, compat_ptr(tmp.counters));
    if (ret)
        goto free_newinfo_untrans;
    return 0;

 free_newinfo_untrans:
    xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
        cleanup_entry(iter);
 free_newinfo:
    xt_free_table_info(newinfo);
    return ret;
}

static int compat_do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user,
                  unsigned int len)
{
    int ret;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    switch (cmd) {
    case ARPT_SO_SET_REPLACE:
        ret = compat_do_replace(sock_net(sk), user, len);
        break;

    case ARPT_SO_SET_ADD_COUNTERS:
        ret = do_add_counters(sock_net(sk), user, len, 1);
        break;

    default:
        duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
        ret = -EINVAL;
    }

    return ret;
}

static int compat_copy_entry_to_user(struct arpt_entry *e, void __user **dstptr,
                     compat_uint_t *size,
                     struct xt_counters *counters,
                     unsigned int i)
{
    struct xt_entry_target *t;
    struct compat_arpt_entry __user *ce;
    u_int16_t target_offset, next_offset;
    compat_uint_t origsize;
    int ret;

    origsize = *size;
    ce = (struct compat_arpt_entry __user *)*dstptr;
    if (copy_to_user(ce, e, sizeof(struct arpt_entry)) != 0 ||
        copy_to_user(&ce->counters, &counters[i],
        sizeof(counters[i])) != 0)
        return -EFAULT;

    *dstptr += sizeof(struct compat_arpt_entry);
    *size -= sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);

    target_offset = e->target_offset - (origsize - *size);

    t = arpt_get_target(e);
    ret = xt_compat_target_to_user(t, dstptr, size);
    if (ret)
        return ret;
    next_offset = e->next_offset - (origsize - *size);
    if (put_user(target_offset, &ce->target_offset) != 0 ||
        put_user(next_offset, &ce->next_offset) != 0)
        return -EFAULT;
    return 0;
}

static int compat_copy_entries_to_user(unsigned int total_size,
                       struct xt_table *table,
                       void __user *userptr)
{
    struct xt_counters *counters;
    const struct xt_table_info *private = table->private;
    void __user *pos;
    unsigned int size;
    int ret = 0;
    void *loc_cpu_entry;
    unsigned int i = 0;
    struct arpt_entry *iter;

    counters = alloc_counters(table);
    if (IS_ERR(counters))
        return PTR_ERR(counters);

    /* choose the copy on our node/cpu */
    loc_cpu_entry = private->entries[raw_smp_processor_id()];
    pos = userptr;
    size = total_size;
    xt_entry_foreach(iter, loc_cpu_entry, total_size) {
        ret = compat_copy_entry_to_user(iter, &pos,
                        &size, counters, i++);
        if (ret != 0)
            break;
    }
    vfree(counters);
    return ret;
}

struct compat_arpt_get_entries {
    char name[XT_TABLE_MAXNAMELEN];
    compat_uint_t size;
    struct compat_arpt_entry entrytable[0];
};

static int compat_get_entries(struct net *net,
                  struct compat_arpt_get_entries __user *uptr,
                  int *len)
{
    int ret;
    struct compat_arpt_get_entries get;
    struct xt_table *t;

    if (*len < sizeof(get)) {
        duprintf("compat_get_entries: %u < %zu\n", *len, sizeof(get));
        return -EINVAL;
    }
    if (copy_from_user(&get, uptr, sizeof(get)) != 0)
        return -EFAULT;
    if (*len != sizeof(struct compat_arpt_get_entries) + get.size) {
        duprintf("compat_get_entries: %u != %zu\n",
             *len, sizeof(get) + get.size);
        return -EINVAL;
    }

    xt_compat_lock(NFPROTO_ARP);
    t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
    if (t && !IS_ERR(t)) {
        const struct xt_table_info *private = t->private;
        struct xt_table_info info;

        duprintf("t->private->number = %u\n", private->number);
        ret = compat_table_info(private, &info);
        if (!ret && get.size == info.size) {
            ret = compat_copy_entries_to_user(private->size,
                              t, uptr->entrytable);
        } else if (!ret) {
            duprintf("compat_get_entries: I've got %u not %u!\n",
                 private->size, get.size);
            ret = -EAGAIN;
        }
        xt_compat_flush_offsets(NFPROTO_ARP);
        module_put(t->me);
        xt_table_unlock(t);
    } else
        ret = t ? PTR_ERR(t) : -ENOENT;

    xt_compat_unlock(NFPROTO_ARP);
    return ret;
}

static int do_arpt_get_ctl(struct sock *, int, void __user *, int *);

static int compat_do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user,
                  int *len)
{
    int ret;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    switch (cmd) {
    case ARPT_SO_GET_INFO:
        ret = get_info(sock_net(sk), user, len, 1);
        break;
    case ARPT_SO_GET_ENTRIES:
        ret = compat_get_entries(sock_net(sk), user, len);
        break;
    default:
        ret = do_arpt_get_ctl(sk, cmd, user, len);
    }
    return ret;
}
#endif

static int do_arpt_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
{
    int ret;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    switch (cmd) {
    case ARPT_SO_SET_REPLACE:
        ret = do_replace(sock_net(sk), user, len);
        break;

    case ARPT_SO_SET_ADD_COUNTERS:
        ret = do_add_counters(sock_net(sk), user, len, 0);
        break;

    default:
        duprintf("do_arpt_set_ctl:  unknown request %i\n", cmd);
        ret = -EINVAL;
    }

    return ret;
}

static int do_arpt_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
{
    int ret;

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    switch (cmd) {
    case ARPT_SO_GET_INFO:
        ret = get_info(sock_net(sk), user, len, 0);
        break;

    case ARPT_SO_GET_ENTRIES:
        ret = get_entries(sock_net(sk), user, len);
        break;

    case ARPT_SO_GET_REVISION_TARGET: {
        struct xt_get_revision rev;

        if (*len != sizeof(rev)) {
            ret = -EINVAL;
            break;
        }
        if (copy_from_user(&rev, user, sizeof(rev)) != 0) {
            ret = -EFAULT;
            break;
        }
        rev.name[sizeof(rev.name)-1] = 0;

        try_then_request_module(xt_find_revision(NFPROTO_ARP, rev.name,
                             rev.revision, 1, &ret),
                    "arpt_%s", rev.name);
        break;
    }

    default:
        duprintf("do_arpt_get_ctl: unknown request %i\n", cmd);
        ret = -EINVAL;
    }

    return ret;
}

struct xt_table *arpt_register_table(struct net *net,
                     const struct xt_table *table,
                     const struct arpt_replace *repl)
{
    int ret;
    struct xt_table_info *newinfo;
    struct xt_table_info bootstrap = {0};
    void *loc_cpu_entry;
    struct xt_table *new_table;

    newinfo = xt_alloc_table_info(repl->size);
    if (!newinfo) {
        ret = -ENOMEM;
        goto out;
    }

    /* choose the copy on our node/cpu */
    loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
    memcpy(loc_cpu_entry, repl->entries, repl->size);

    ret = translate_table(newinfo, loc_cpu_entry, repl);
    duprintf("arpt_register_table: translate table gives %d\n", ret);
    if (ret != 0)
        goto out_free;

    new_table = xt_register_table(net, table, &bootstrap, newinfo);
    if (IS_ERR(new_table)) {
        ret = PTR_ERR(new_table);
        goto out_free;
    }
    return new_table;

out_free:
    xt_free_table_info(newinfo);
out:
    return ERR_PTR(ret);
}

void arpt_unregister_table(struct xt_table *table)
{
    struct xt_table_info *private;
    void *loc_cpu_entry;
    struct module *table_owner = table->me;
    struct arpt_entry *iter;

    private = xt_unregister_table(table);

    /* Decrease module usage counts and free resources */
    loc_cpu_entry = private->entries[raw_smp_processor_id()];
    xt_entry_foreach(iter, loc_cpu_entry, private->size)
        cleanup_entry(iter);
    if (private->number > private->initial_entries)
        module_put(table_owner);
    xt_free_table_info(private);
}

/* The built-in targets: standard (NULL) and error. */
static struct xt_target arpt_builtin_tg[] __read_mostly = {
    {
        .name             = XT_STANDARD_TARGET,
        .targetsize       = sizeof(int),
        .family           = NFPROTO_ARP,
#ifdef CONFIG_COMPAT
        .compatsize       = sizeof(compat_int_t),
        .compat_from_user = compat_standard_from_user,
        .compat_to_user   = compat_standard_to_user,
#endif
    },
    {
        .name             = XT_ERROR_TARGET,
        .target           = arpt_error,
        .targetsize       = XT_FUNCTION_MAXNAMELEN,
        .family           = NFPROTO_ARP,
    },
};

static struct nf_sockopt_ops arpt_sockopts = {
    .pf     = PF_INET,
    .set_optmin = ARPT_BASE_CTL,
    .set_optmax = ARPT_SO_SET_MAX+1,
    .set        = do_arpt_set_ctl,
#ifdef CONFIG_COMPAT
    .compat_set = compat_do_arpt_set_ctl,
#endif
    .get_optmin = ARPT_BASE_CTL,
    .get_optmax = ARPT_SO_GET_MAX+1,
    .get        = do_arpt_get_ctl,
#ifdef CONFIG_COMPAT
    .compat_get = compat_do_arpt_get_ctl,
#endif
    .owner      = THIS_MODULE,
};

static int __net_init arp_tables_net_init(struct net *net)
{
    return xt_proto_init(net, NFPROTO_ARP);
}

static void __net_exit arp_tables_net_exit(struct net *net)
{
    xt_proto_fini(net, NFPROTO_ARP);
}

static struct pernet_operations arp_tables_net_ops = {
    .init = arp_tables_net_init,
    .exit = arp_tables_net_exit,
};

static int __init arp_tables_init(void)
{
    int ret;

    ret = register_pernet_subsys(&arp_tables_net_ops);
    if (ret < 0)
        goto err1;

    /* No one else will be downing sem now, so we won't sleep */
    ret = xt_register_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
    if (ret < 0)
        goto err2;

    /* Register setsockopt */
    ret = nf_register_sockopt(&arpt_sockopts);
    if (ret < 0)
        goto err4;

    printk(KERN_INFO "arp_tables: (C) 2002 David S. Miller\n");
    return 0;

err4:
    xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
err2:
    unregister_pernet_subsys(&arp_tables_net_ops);
err1:
    return ret;
}

static void __exit arp_tables_fini(void)
{
    nf_unregister_sockopt(&arpt_sockopts);
    xt_unregister_targets(arpt_builtin_tg, ARRAY_SIZE(arpt_builtin_tg));
    unregister_pernet_subsys(&arp_tables_net_ops);
}

EXPORT_SYMBOL(arpt_register_table);
EXPORT_SYMBOL(arpt_unregister_table);
EXPORT_SYMBOL(arpt_do_table);

module_init(arp_tables_init);
module_exit(arp_tables_fini);