ip_tables.c

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/*
 * Packet matching code.
 *
 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
 * Copyright (C) 2000-2005 Netfilter Core Team <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/cache.h>
#include <linux/capability.h>
#include <linux/skbuff.h>
#include <linux/kmod.h>
#include <linux/vmalloc.h>
#include <linux/netdevice.h>
#include <linux/module.h>
#include <linux/icmp.h>
#include <net/ip.h>
#include <net/compat.h>
#include <asm/uaccess.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/err.h>
#include <linux/cpumask.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <net/netfilter/nf_log.h>
#include "../../netfilter/xt_repldata.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <[email protected]>");
MODULE_DESCRIPTION("IPv4 packet filter");

/*#define DEBUG_IP_FIREWALL*/
/*#define DEBUG_ALLOW_ALL*/ /* Useful for remote debugging */
/*#define DEBUG_IP_FIREWALL_USER*/

#ifdef DEBUG_IP_FIREWALL
#define dprintf(format, args...) pr_info(format , ## args)
#else
#define dprintf(format, args...)
#endif

#ifdef DEBUG_IP_FIREWALL_USER
#define duprintf(format, args...) pr_info(format , ## args)
#else
#define duprintf(format, args...)
#endif

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

#if 0
/* All the better to debug you with... */
#define static
#define inline
#endif

void *ipt_alloc_initial_table(const struct xt_table *info)
{
    return xt_alloc_initial_table(ipt, IPT);
}
EXPORT_SYMBOL_GPL(ipt_alloc_initial_table);

/* Returns whether matches rule or not. */
/* Performance critical - called for every packet */
static inline bool
ip_packet_match(const struct iphdr *ip,
        const char *indev,
        const char *outdev,
        const struct ipt_ip *ipinfo,
        int isfrag)
{
    unsigned long ret;

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

    if (FWINV((ip->saddr&ipinfo->smsk.s_addr) != ipinfo->src.s_addr,
          IPT_INV_SRCIP) ||
        FWINV((ip->daddr&ipinfo->dmsk.s_addr) != ipinfo->dst.s_addr,
          IPT_INV_DSTIP)) {
        dprintf("Source or dest mismatch.\n");

        dprintf("SRC: %pI4. Mask: %pI4. Target: %pI4.%s\n",
            &ip->saddr, &ipinfo->smsk.s_addr, &ipinfo->src.s_addr,
            ipinfo->invflags & IPT_INV_SRCIP ? " (INV)" : "");
        dprintf("DST: %pI4 Mask: %pI4 Target: %pI4.%s\n",
            &ip->daddr, &ipinfo->dmsk.s_addr, &ipinfo->dst.s_addr,
            ipinfo->invflags & IPT_INV_DSTIP ? " (INV)" : "");
        return false;
    }

    ret = ifname_compare_aligned(indev, ipinfo->iniface, ipinfo->iniface_mask);

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

    ret = ifname_compare_aligned(outdev, ipinfo->outiface, ipinfo->outiface_mask);

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

    /* Check specific protocol */
    if (ipinfo->proto &&
        FWINV(ip->protocol != ipinfo->proto, IPT_INV_PROTO)) {
        dprintf("Packet protocol %hi does not match %hi.%s\n",
            ip->protocol, ipinfo->proto,
            ipinfo->invflags&IPT_INV_PROTO ? " (INV)":"");
        return false;
    }

    /* If we have a fragment rule but the packet is not a fragment
     * then we return zero */
    if (FWINV((ipinfo->flags&IPT_F_FRAG) && !isfrag, IPT_INV_FRAG)) {
        dprintf("Fragment rule but not fragment.%s\n",
            ipinfo->invflags & IPT_INV_FRAG ? " (INV)" : "");
        return false;
    }

    return true;
}

static bool
ip_checkentry(const struct ipt_ip *ip)
{
    if (ip->flags & ~IPT_F_MASK) {
        duprintf("Unknown flag bits set: %08X\n",
             ip->flags & ~IPT_F_MASK);
        return false;
    }
    if (ip->invflags & ~IPT_INV_MASK) {
        duprintf("Unknown invflag bits set: %08X\n",
             ip->invflags & ~IPT_INV_MASK);
        return false;
    }
    return true;
}

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

    return NF_DROP;
}

/* Performance critical */
static inline struct ipt_entry *
get_entry(const void *base, unsigned int offset)
{
    return (struct ipt_entry *)(base + offset);
}

/* All zeroes == unconditional rule. */
/* Mildly perf critical (only if packet tracing is on) */
static inline bool unconditional(const struct ipt_ip *ip)
{
    static const struct ipt_ip uncond;

    return memcmp(ip, &uncond, sizeof(uncond)) == 0;
#undef FWINV
}

/* for const-correctness */
static inline const struct xt_entry_target *
ipt_get_target_c(const struct ipt_entry *e)
{
    return ipt_get_target((struct ipt_entry *)e);
}

#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
static const char *const hooknames[] = {
    [NF_INET_PRE_ROUTING]       = "PREROUTING",
    [NF_INET_LOCAL_IN]      = "INPUT",
    [NF_INET_FORWARD]       = "FORWARD",
    [NF_INET_LOCAL_OUT]     = "OUTPUT",
    [NF_INET_POST_ROUTING]      = "POSTROUTING",
};

enum nf_ip_trace_comments {
    NF_IP_TRACE_COMMENT_RULE,
    NF_IP_TRACE_COMMENT_RETURN,
    NF_IP_TRACE_COMMENT_POLICY,
};

static const char *const comments[] = {
    [NF_IP_TRACE_COMMENT_RULE]  = "rule",
    [NF_IP_TRACE_COMMENT_RETURN]    = "return",
    [NF_IP_TRACE_COMMENT_POLICY]    = "policy",
};

static struct nf_loginfo trace_loginfo = {
    .type = NF_LOG_TYPE_LOG,
    .u = {
        .log = {
            .level = 4,
            .logflags = NF_LOG_MASK,
        },
    },
};

/* Mildly perf critical (only if packet tracing is on) */
static inline int
get_chainname_rulenum(const struct ipt_entry *s, const struct ipt_entry *e,
              const char *hookname, const char **chainname,
              const char **comment, unsigned int *rulenum)
{
    const struct xt_standard_target *t = (void *)ipt_get_target_c(s);

    if (strcmp(t->target.u.kernel.target->name, XT_ERROR_TARGET) == 0) {
        /* Head of user chain: ERROR target with chainname */
        *chainname = t->target.data;
        (*rulenum) = 0;
    } else if (s == e) {
        (*rulenum)++;

        if (s->target_offset == sizeof(struct ipt_entry) &&
            strcmp(t->target.u.kernel.target->name,
               XT_STANDARD_TARGET) == 0 &&
           t->verdict < 0 &&
           unconditional(&s->ip)) {
            /* Tail of chains: STANDARD target (return/policy) */
            *comment = *chainname == hookname
                ? comments[NF_IP_TRACE_COMMENT_POLICY]
                : comments[NF_IP_TRACE_COMMENT_RETURN];
        }
        return 1;
    } else
        (*rulenum)++;

    return 0;
}

static void trace_packet(const struct sk_buff *skb,
             unsigned int hook,
             const struct net_device *in,
             const struct net_device *out,
             const char *tablename,
             const struct xt_table_info *private,
             const struct ipt_entry *e)
{
    const void *table_base;
    const struct ipt_entry *root;
    const char *hookname, *chainname, *comment;
    const struct ipt_entry *iter;
    unsigned int rulenum = 0;

    table_base = private->entries[smp_processor_id()];
    root = get_entry(table_base, private->hook_entry[hook]);

    hookname = chainname = hooknames[hook];
    comment = comments[NF_IP_TRACE_COMMENT_RULE];

    xt_entry_foreach(iter, root, private->size - private->hook_entry[hook])
        if (get_chainname_rulenum(iter, e, hookname,
            &chainname, &comment, &rulenum) != 0)
            break;

    nf_log_packet(AF_INET, hook, skb, in, out, &trace_loginfo,
              "TRACE: %s:%s:%s:%u ",
              tablename, chainname, comment, rulenum);
}
#endif

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

/* Returns one of the generic firewall policies, like NF_ACCEPT. */
unsigned int
ipt_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))));
    const struct iphdr *ip;
    /* Initializing verdict to NF_DROP keeps gcc happy. */
    unsigned int verdict = NF_DROP;
    const char *indev, *outdev;
    const void *table_base;
    struct ipt_entry *e, **jumpstack;
    unsigned int *stackptr, origptr, cpu;
    const struct xt_table_info *private;
    struct xt_action_param acpar;
    unsigned int addend;

    /* Initialization */
    ip = ip_hdr(skb);
    indev = in ? in->name : nulldevname;
    outdev = out ? out->name : nulldevname;
    /* We handle fragments by dealing with the first fragment as
     * if it was a normal packet.  All other fragments are treated
     * normally, except that they will NEVER match rules that ask
     * things we don't know, ie. tcp syn flag or ports).  If the
     * rule is also a fragment-specific rule, non-fragments won't
     * match it. */
    acpar.fragoff = ntohs(ip->frag_off) & IP_OFFSET;
    acpar.thoff   = ip_hdrlen(skb);
    acpar.hotdrop = false;
    acpar.in      = in;
    acpar.out     = out;
    acpar.family  = NFPROTO_IPV4;
    acpar.hooknum = hook;

    IP_NF_ASSERT(table->valid_hooks & (1 << hook));
    local_bh_disable();
    addend = xt_write_recseq_begin();
    private = table->private;
    cpu        = smp_processor_id();
    table_base = private->entries[cpu];
    jumpstack  = (struct ipt_entry **)private->jumpstack[cpu];
    stackptr   = per_cpu_ptr(private->stackptr, cpu);
    origptr    = *stackptr;

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

    pr_debug("Entering %s(hook %u); sp at %u (UF %p)\n",
         table->name, hook, origptr,
         get_entry(table_base, private->underflow[hook]));

    do {
        const struct xt_entry_target *t;
        const struct xt_entry_match *ematch;

        IP_NF_ASSERT(e);
        if (!ip_packet_match(ip, indev, outdev,
            &e->ip, acpar.fragoff)) {
 no_match:
            e = ipt_next_entry(e);
            continue;
        }

        xt_ematch_foreach(ematch, e) {
            acpar.match     = ematch->u.kernel.match;
            acpar.matchinfo = ematch->data;
            if (!acpar.match->match(skb, &acpar))
                goto no_match;
        }

        ADD_COUNTER(e->counters, skb->len, 1);

        t = ipt_get_target(e);
        IP_NF_ASSERT(t->u.kernel.target);

#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
        /* The packet is traced: log it */
        if (unlikely(skb->nf_trace))
            trace_packet(skb, hook, in, out,
                     table->name, private, e);
#endif
        /* Standard target? */
        if (!t->u.kernel.target->target) {
            int v;

            v = ((struct xt_standard_target *)t)->verdict;
            if (v < 0) {
                /* Pop from stack? */
                if (v != XT_RETURN) {
                    verdict = (unsigned int)(-v) - 1;
                    break;
                }
                if (*stackptr <= origptr) {
                    e = get_entry(table_base,
                        private->underflow[hook]);
                    pr_debug("Underflow (this is normal) "
                         "to %p\n", e);
                } else {
                    e = jumpstack[--*stackptr];
                    pr_debug("Pulled %p out from pos %u\n",
                         e, *stackptr);
                    e = ipt_next_entry(e);
                }
                continue;
            }
            if (table_base + v != ipt_next_entry(e) &&
                !(e->ip.flags & IPT_F_GOTO)) {
                if (*stackptr >= private->stacksize) {
                    verdict = NF_DROP;
                    break;
                }
                jumpstack[(*stackptr)++] = e;
                pr_debug("Pushed %p into pos %u\n",
                     e, *stackptr - 1);
            }

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

        acpar.target   = t->u.kernel.target;
        acpar.targinfo = t->data;

        verdict = t->u.kernel.target->target(skb, &acpar);
        /* Target might have changed stuff. */
        ip = ip_hdr(skb);
        if (verdict == XT_CONTINUE)
            e = ipt_next_entry(e);
        else
            /* Verdict */
            break;
    } while (!acpar.hotdrop);
    pr_debug("Exiting %s; resetting sp from %u to %u\n",
         __func__, *stackptr, origptr);
    *stackptr = origptr;
    xt_write_recseq_end(addend);
    local_bh_enable();

#ifdef DEBUG_ALLOW_ALL
    return NF_ACCEPT;
#else
    if (acpar.hotdrop)
        return NF_DROP;
    else return verdict;
#endif
}

/* 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_INET_NUMHOOKS; hook++) {
        unsigned int pos = newinfo->hook_entry[hook];
        struct ipt_entry *e = (struct ipt_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 *)ipt_get_target_c(e);
            int visited = e->comefrom & (1 << hook);

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

            /* Unconditional return/END. */
            if ((e->target_offset == sizeof(struct ipt_entry) &&
                 (strcmp(t->target.u.user.name,
                     XT_STANDARD_TARGET) == 0) &&
                 t->verdict < 0 && unconditional(&e->ip)) ||
                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_INET_NUMHOOKS);
#ifdef DEBUG_IP_FIREWALL_USER
                    if (e->comefrom
                        & (1 << NF_INET_NUMHOOKS)) {
                        duprintf("Back unset "
                             "on hook %u "
                             "rule %u\n",
                             hook, pos);
                    }
#endif
                    oldpos = pos;
                    pos = e->counters.pcnt;
                    e->counters.pcnt = 0;

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

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

                /* Move along one */
                size = e->next_offset;
                e = (struct ipt_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 ipt_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 ipt_entry *)
                    (entry0 + newpos);
                e->counters.pcnt = pos;
                pos = newpos;
            }
        }
        next:
        duprintf("Finished chain %u\n", hook);
    }
    return 1;
}

static void cleanup_match(struct xt_entry_match *m, struct net *net)
{
    struct xt_mtdtor_param par;

    par.net       = net;
    par.match     = m->u.kernel.match;
    par.matchinfo = m->data;
    par.family    = NFPROTO_IPV4;
    if (par.match->destroy != NULL)
        par.match->destroy(&par);
    module_put(par.match->me);
}

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

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

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

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

    return 0;
}

static int
check_match(struct xt_entry_match *m, struct xt_mtchk_param *par)
{
    const struct ipt_ip *ip = par->entryinfo;
    int ret;

    par->match     = m->u.kernel.match;
    par->matchinfo = m->data;

    ret = xt_check_match(par, m->u.match_size - sizeof(*m),
          ip->proto, ip->invflags & IPT_INV_PROTO);
    if (ret < 0) {
        duprintf("check failed for `%s'.\n", par->match->name);
        return ret;
    }
    return 0;
}

static int
find_check_match(struct xt_entry_match *m, struct xt_mtchk_param *par)
{
    struct xt_match *match;
    int ret;

    match = xt_request_find_match(NFPROTO_IPV4, m->u.user.name,
                      m->u.user.revision);
    if (IS_ERR(match)) {
        duprintf("find_check_match: `%s' not found\n", m->u.user.name);
        return PTR_ERR(match);
    }
    m->u.kernel.match = match;

    ret = check_match(m, par);
    if (ret)
        goto err;

    return 0;
err:
    module_put(m->u.kernel.match->me);
    return ret;
}

static int check_target(struct ipt_entry *e, struct net *net, const char *name)
{
    struct xt_entry_target *t = ipt_get_target(e);
    struct xt_tgchk_param par = {
        .net       = net,
        .table     = name,
        .entryinfo = e,
        .target    = t->u.kernel.target,
        .targinfo  = t->data,
        .hook_mask = e->comefrom,
        .family    = NFPROTO_IPV4,
    };
    int ret;

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

static int
find_check_entry(struct ipt_entry *e, struct net *net, const char *name,
         unsigned int size)
{
    struct xt_entry_target *t;
    struct xt_target *target;
    int ret;
    unsigned int j;
    struct xt_mtchk_param mtpar;
    struct xt_entry_match *ematch;

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

    j = 0;
    mtpar.net   = net;
    mtpar.table     = name;
    mtpar.entryinfo = &e->ip;
    mtpar.hook_mask = e->comefrom;
    mtpar.family    = NFPROTO_IPV4;
    xt_ematch_foreach(ematch, e) {
        ret = find_check_match(ematch, &mtpar);
        if (ret != 0)
            goto cleanup_matches;
        ++j;
    }

    t = ipt_get_target(e);
    target = xt_request_find_target(NFPROTO_IPV4, 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 cleanup_matches;
    }
    t->u.kernel.target = target;

    ret = check_target(e, net, name);
    if (ret)
        goto err;
    return 0;
 err:
    module_put(t->u.kernel.target->me);
 cleanup_matches:
    xt_ematch_foreach(ematch, e) {
        if (j-- == 0)
            break;
        cleanup_match(ematch, net);
    }
    return ret;
}

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

    if (!unconditional(&e->ip))
        return false;
    t = ipt_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 int
check_entry_size_and_hooks(struct ipt_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 ipt_entry) != 0 ||
        (unsigned char *)e + sizeof(struct ipt_entry) >= limit) {
        duprintf("Bad offset %p\n", e);
        return -EINVAL;
    }

    if (e->next_offset
        < sizeof(struct ipt_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_INET_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 void
cleanup_entry(struct ipt_entry *e, struct net *net)
{
    struct xt_tgdtor_param par;
    struct xt_entry_target *t;
    struct xt_entry_match *ematch;

    /* Cleanup all matches */
    xt_ematch_foreach(ematch, e)
        cleanup_match(ematch, net);
    t = ipt_get_target(e);

    par.net      = net;
    par.target   = t->u.kernel.target;
    par.targinfo = t->data;
    par.family   = NFPROTO_IPV4;
    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 net *net, struct xt_table_info *newinfo, void *entry0,
                const struct ipt_replace *repl)
{
    struct ipt_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_INET_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)
            return ret;
        ++i;
        if (strcmp(ipt_get_target(iter)->u.user.name,
            XT_ERROR_TARGET) == 0)
            ++newinfo->stacksize;
    }

    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_INET_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))
        return -ELOOP;

    /* Finally, each sanity check must pass */
    i = 0;
    xt_entry_foreach(iter, entry0, newinfo->size) {
        ret = find_check_entry(iter, net, 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, net);
        }
        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 ipt_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; /* macro does multi eval of 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 ipt_entry *e;
    struct xt_counters *counters;
    const struct xt_table_info *private = table->private;
    int ret = 0;
    const void *loc_cpu_entry;

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

    /* choose the copy that is on our node/cpu, ...
     * This choice is lazy (because current thread is
     * allowed to migrate to another cpu)
     */
    loc_cpu_entry = private->entries[raw_smp_processor_id()];
    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++){
        unsigned int i;
        const struct xt_entry_match *m;
        const struct xt_entry_target *t;

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

        for (i = sizeof(struct ipt_entry);
             i < e->target_offset;
             i += m->u.match_size) {
            m = (void *)e + i;

            if (copy_to_user(userptr + off + i
                     + offsetof(struct xt_entry_match,
                            u.user.name),
                     m->u.kernel.match->name,
                     strlen(m->u.kernel.match->name)+1)
                != 0) {
                ret = -EFAULT;
                goto free_counters;
            }
        }

        t = ipt_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(AF_INET, 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(AF_INET, cv);
    return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
}

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

    off = sizeof(struct ipt_entry) - sizeof(struct compat_ipt_entry);
    entry_offset = (void *)e - base;
    xt_ematch_foreach(ematch, e)
        off += xt_compat_match_offset(ematch->u.kernel.match);
    t = ipt_get_target_c(e);
    off += xt_compat_target_offset(t->u.kernel.target);
    newinfo->size -= off;
    ret = xt_compat_add_offset(AF_INET, entry_offset, off);
    if (ret)
        return ret;

    for (i = 0; i < NF_INET_NUMHOOKS; i++) {
        if (info->hook_entry[i] &&
            (e < (struct ipt_entry *)(base + info->hook_entry[i])))
            newinfo->hook_entry[i] -= off;
        if (info->underflow[i] &&
            (e < (struct ipt_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 ipt_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(AF_INET, 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 ipt_getinfo)) {
        duprintf("length %u != %zu\n", *len,
             sizeof(struct ipt_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(AF_INET);
#endif
    t = try_then_request_module(xt_find_table_lock(net, AF_INET, name),
                    "iptable_%s", name);
    if (t && !IS_ERR(t)) {
        struct ipt_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(AF_INET);
            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(AF_INET);
#endif
    return ret;
}

static int
get_entries(struct net *net, struct ipt_get_entries __user *uptr,
        const int *len)
{
    int ret;
    struct ipt_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 ipt_get_entries) + get.size) {
        duprintf("get_entries: %u != %zu\n",
             *len, sizeof(get) + get.size);
        return -EINVAL;
    }

    t = xt_find_table_lock(net, AF_INET, 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 ipt_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, AF_INET, name),
                    "iptable_%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, net);

    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 ipt_replace tmp;
    struct xt_table_info *newinfo;
    void *loc_cpu_entry;
    struct ipt_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(net, newinfo, loc_cpu_entry, &tmp);
    if (ret != 0)
        goto free_newinfo;

    duprintf("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, net);
 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 ipt_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, AF_INET, 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
struct compat_ipt_replace {
    char            name[XT_TABLE_MAXNAMELEN];
    u32         valid_hooks;
    u32         num_entries;
    u32         size;
    u32         hook_entry[NF_INET_NUMHOOKS];
    u32         underflow[NF_INET_NUMHOOKS];
    u32         num_counters;
    compat_uptr_t       counters;   /* struct xt_counters * */
    struct compat_ipt_entry entries[0];
};

static int
compat_copy_entry_to_user(struct ipt_entry *e, void __user **dstptr,
              unsigned int *size, struct xt_counters *counters,
              unsigned int i)
{
    struct xt_entry_target *t;
    struct compat_ipt_entry __user *ce;
    u_int16_t target_offset, next_offset;
    compat_uint_t origsize;
    const struct xt_entry_match *ematch;
    int ret = 0;

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

    *dstptr += sizeof(struct compat_ipt_entry);
    *size -= sizeof(struct ipt_entry) - sizeof(struct compat_ipt_entry);

    xt_ematch_foreach(ematch, e) {
        ret = xt_compat_match_to_user(ematch, dstptr, size);
        if (ret != 0)
            return ret;
    }
    target_offset = e->target_offset - (origsize - *size);
    t = ipt_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_find_calc_match(struct xt_entry_match *m,
               const char *name,
               const struct ipt_ip *ip,
               unsigned int hookmask,
               int *size)
{
    struct xt_match *match;

    match = xt_request_find_match(NFPROTO_IPV4, m->u.user.name,
                      m->u.user.revision);
    if (IS_ERR(match)) {
        duprintf("compat_check_calc_match: `%s' not found\n",
             m->u.user.name);
        return PTR_ERR(match);
    }
    m->u.kernel.match = match;
    *size += xt_compat_match_offset(match);
    return 0;
}

static void compat_release_entry(struct compat_ipt_entry *e)
{
    struct xt_entry_target *t;
    struct xt_entry_match *ematch;

    /* Cleanup all matches */
    xt_ematch_foreach(ematch, e)
        module_put(ematch->u.kernel.match->me);
    t = compat_ipt_get_target(e);
    module_put(t->u.kernel.target->me);
}

static int
check_compat_entry_size_and_hooks(struct compat_ipt_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_match *ematch;
    struct xt_entry_target *t;
    struct xt_target *target;
    unsigned int entry_offset;
    unsigned int j;
    int ret, off, h;

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

    if (e->next_offset < sizeof(struct compat_ipt_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 ipt_entry *)e, name);
    if (ret)
        return ret;

    off = sizeof(struct ipt_entry) - sizeof(struct compat_ipt_entry);
    entry_offset = (void *)e - (void *)base;
    j = 0;
    xt_ematch_foreach(ematch, e) {
        ret = compat_find_calc_match(ematch, name,
                         &e->ip, e->comefrom, &off);
        if (ret != 0)
            goto release_matches;
        ++j;
    }

    t = compat_ipt_get_target(e);
    target = xt_request_find_target(NFPROTO_IPV4, 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 release_matches;
    }
    t->u.kernel.target = target;

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

    /* Check hooks & underflows */
    for (h = 0; h < NF_INET_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;

out:
    module_put(t->u.kernel.target->me);
release_matches:
    xt_ematch_foreach(ematch, e) {
        if (j-- == 0)
            break;
        module_put(ematch->u.kernel.match->me);
    }
    return ret;
}

static int
compat_copy_entry_from_user(struct compat_ipt_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 ipt_entry *de;
    unsigned int origsize;
    int ret, h;
    struct xt_entry_match *ematch;

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

    *dstptr += sizeof(struct ipt_entry);
    *size += sizeof(struct ipt_entry) - sizeof(struct compat_ipt_entry);

    xt_ematch_foreach(ematch, e) {
        ret = xt_compat_match_from_user(ematch, dstptr, size);
        if (ret != 0)
            return ret;
    }
    de->target_offset = e->target_offset - (origsize - *size);
    t = compat_ipt_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_INET_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
compat_check_entry(struct ipt_entry *e, struct net *net, const char *name)
{
    struct xt_entry_match *ematch;
    struct xt_mtchk_param mtpar;
    unsigned int j;
    int ret = 0;

    j = 0;
    mtpar.net   = net;
    mtpar.table     = name;
    mtpar.entryinfo = &e->ip;
    mtpar.hook_mask = e->comefrom;
    mtpar.family    = NFPROTO_IPV4;
    xt_ematch_foreach(ematch, e) {
        ret = check_match(ematch, &mtpar);
        if (ret != 0)
            goto cleanup_matches;
        ++j;
    }

    ret = check_target(e, net, name);
    if (ret)
        goto cleanup_matches;
    return 0;

 cleanup_matches:
    xt_ematch_foreach(ematch, e) {
        if (j-- == 0)
            break;
        cleanup_match(ematch, net);
    }
    return ret;
}

static int
translate_compat_table(struct net *net,
               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_ipt_entry *iter0;
    struct ipt_entry *iter1;
    unsigned int size;
    int ret;

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

    /* Init all hooks to impossible value. */
    for (i = 0; i < NF_INET_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(AF_INET);
    xt_compat_init_offsets(AF_INET, 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_INET_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_INET_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(AF_INET);
    xt_compat_unlock(AF_INET);
    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 = compat_check_entry(iter1, net, name);
        if (ret != 0)
            break;
        ++i;
        if (strcmp(ipt_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, net);
        }
        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(AF_INET);
    xt_compat_unlock(AF_INET);
    goto out;
}

static int
compat_do_replace(struct net *net, void __user *user, unsigned int len)
{
    int ret;
    struct compat_ipt_replace tmp;
    struct xt_table_info *newinfo;
    void *loc_cpu_entry;
    struct ipt_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(net, 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, net);
 free_newinfo:
    xt_free_table_info(newinfo);
    return ret;
}

static int
compat_do_ipt_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 IPT_SO_SET_REPLACE:
        ret = compat_do_replace(sock_net(sk), user, len);
        break;

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

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

    return ret;
}

struct compat_ipt_get_entries {
    char name[XT_TABLE_MAXNAMELEN];
    compat_uint_t size;
    struct compat_ipt_entry entrytable[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;
    const void *loc_cpu_entry;
    unsigned int i = 0;
    struct ipt_entry *iter;

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

    /* choose the copy that is on our node/cpu, ...
     * This choice is lazy (because current thread is
     * allowed to migrate to another 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;
}

static int
compat_get_entries(struct net *net, struct compat_ipt_get_entries __user *uptr,
           int *len)
{
    int ret;
    struct compat_ipt_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_ipt_get_entries) + get.size) {
        duprintf("compat_get_entries: %u != %zu\n",
             *len, sizeof(get) + get.size);
        return -EINVAL;
    }

    xt_compat_lock(AF_INET);
    t = xt_find_table_lock(net, AF_INET, 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(AF_INET);
        module_put(t->me);
        xt_table_unlock(t);
    } else
        ret = t ? PTR_ERR(t) : -ENOENT;

    xt_compat_unlock(AF_INET);
    return ret;
}

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

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

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

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

static int
do_ipt_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 IPT_SO_SET_REPLACE:
        ret = do_replace(sock_net(sk), user, len);
        break;

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

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

    return ret;
}

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

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

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

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

    case IPT_SO_GET_REVISION_MATCH:
    case IPT_SO_GET_REVISION_TARGET: {
        struct xt_get_revision rev;
        int target;

        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;

        if (cmd == IPT_SO_GET_REVISION_TARGET)
            target = 1;
        else
            target = 0;

        try_then_request_module(xt_find_revision(AF_INET, rev.name,
                             rev.revision,
                             target, &ret),
                    "ipt_%s", rev.name);
        break;
    }

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

    return ret;
}

struct xt_table *ipt_register_table(struct net *net,
                    const struct xt_table *table,
                    const struct ipt_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, but dont care about preemption */
    loc_cpu_entry = newinfo->entries[raw_smp_processor_id()];
    memcpy(loc_cpu_entry, repl->entries, repl->size);

    ret = translate_table(net, newinfo, loc_cpu_entry, repl);
    if (ret != 0)
        goto out_free;

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

    return new_table;

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

void ipt_unregister_table(struct net *net, struct xt_table *table)
{
    struct xt_table_info *private;
    void *loc_cpu_entry;
    struct module *table_owner = table->me;
    struct ipt_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, net);
    if (private->number > private->initial_entries)
        module_put(table_owner);
    xt_free_table_info(private);
}

/* Returns 1 if the type and code is matched by the range, 0 otherwise */
static inline bool
icmp_type_code_match(u_int8_t test_type, u_int8_t min_code, u_int8_t max_code,
             u_int8_t type, u_int8_t code,
             bool invert)
{
    return ((test_type == 0xFF) ||
        (type == test_type && code >= min_code && code <= max_code))
        ^ invert;
}

static bool
icmp_match(const struct sk_buff *skb, struct xt_action_param *par)
{
    const struct icmphdr *ic;
    struct icmphdr _icmph;
    const struct ipt_icmp *icmpinfo = par->matchinfo;

    /* Must not be a fragment. */
    if (par->fragoff != 0)
        return false;

    ic = skb_header_pointer(skb, par->thoff, sizeof(_icmph), &_icmph);
    if (ic == NULL) {
        /* We've been asked to examine this packet, and we
         * can't.  Hence, no choice but to drop.
         */
        duprintf("Dropping evil ICMP tinygram.\n");
        par->hotdrop = true;
        return false;
    }

    return icmp_type_code_match(icmpinfo->type,
                    icmpinfo->code[0],
                    icmpinfo->code[1],
                    ic->type, ic->code,
                    !!(icmpinfo->invflags&IPT_ICMP_INV));
}

static int icmp_checkentry(const struct xt_mtchk_param *par)
{
    const struct ipt_icmp *icmpinfo = par->matchinfo;

    /* Must specify no unknown invflags */
    return (icmpinfo->invflags & ~IPT_ICMP_INV) ? -EINVAL : 0;
}

static struct xt_target ipt_builtin_tg[] __read_mostly = {
    {
        .name             = XT_STANDARD_TARGET,
        .targetsize       = sizeof(int),
        .family           = NFPROTO_IPV4,
#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           = ipt_error,
        .targetsize       = XT_FUNCTION_MAXNAMELEN,
        .family           = NFPROTO_IPV4,
    },
};

static struct nf_sockopt_ops ipt_sockopts = {
    .pf     = PF_INET,
    .set_optmin = IPT_BASE_CTL,
    .set_optmax = IPT_SO_SET_MAX+1,
    .set        = do_ipt_set_ctl,
#ifdef CONFIG_COMPAT
    .compat_set = compat_do_ipt_set_ctl,
#endif
    .get_optmin = IPT_BASE_CTL,
    .get_optmax = IPT_SO_GET_MAX+1,
    .get        = do_ipt_get_ctl,
#ifdef CONFIG_COMPAT
    .compat_get = compat_do_ipt_get_ctl,
#endif
    .owner      = THIS_MODULE,
};

static struct xt_match ipt_builtin_mt[] __read_mostly = {
    {
        .name       = "icmp",
        .match      = icmp_match,
        .matchsize  = sizeof(struct ipt_icmp),
        .checkentry = icmp_checkentry,
        .proto      = IPPROTO_ICMP,
        .family     = NFPROTO_IPV4,
    },
};

static int __net_init ip_tables_net_init(struct net *net)
{
    return xt_proto_init(net, NFPROTO_IPV4);
}

static void __net_exit ip_tables_net_exit(struct net *net)
{
    xt_proto_fini(net, NFPROTO_IPV4);
}

static struct pernet_operations ip_tables_net_ops = {
    .init = ip_tables_net_init,
    .exit = ip_tables_net_exit,
};

static int __init ip_tables_init(void)
{
    int ret;

    ret = register_pernet_subsys(&ip_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(ipt_builtin_tg, ARRAY_SIZE(ipt_builtin_tg));
    if (ret < 0)
        goto err2;
    ret = xt_register_matches(ipt_builtin_mt, ARRAY_SIZE(ipt_builtin_mt));
    if (ret < 0)
        goto err4;

    /* Register setsockopt */
    ret = nf_register_sockopt(&ipt_sockopts);
    if (ret < 0)
        goto err5;

    pr_info("(C) 2000-2006 Netfilter Core Team\n");
    return 0;

err5:
    xt_unregister_matches(ipt_builtin_mt, ARRAY_SIZE(ipt_builtin_mt));
err4:
    xt_unregister_targets(ipt_builtin_tg, ARRAY_SIZE(ipt_builtin_tg));
err2:
    unregister_pernet_subsys(&ip_tables_net_ops);
err1:
    return ret;
}

static void __exit ip_tables_fini(void)
{
    nf_unregister_sockopt(&ipt_sockopts);

    xt_unregister_matches(ipt_builtin_mt, ARRAY_SIZE(ipt_builtin_mt));
    xt_unregister_targets(ipt_builtin_tg, ARRAY_SIZE(ipt_builtin_tg));
    unregister_pernet_subsys(&ip_tables_net_ops);
}

EXPORT_SYMBOL(ipt_register_table);
EXPORT_SYMBOL(ipt_unregister_table);
EXPORT_SYMBOL(ipt_do_table);
module_init(ip_tables_init);
module_exit(ip_tables_fini);