NETFILTER: remove unnecessary goto statement for error recovery

[tomato.git] / release / src-rt / linux / linux-2.6 / net / ipv4 / netfilter / nf_nat_core.c

/* NAT for netfilter; shared with compatibility layer. */

/* (C) 1999-2001 Paul `Rusty' Russell
 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/skbuff.h>
#include <linux/vmalloc.h>
#include <net/checksum.h>
#include <net/icmp.h>
#include <net/ip.h>
#include <net/tcp.h>  /* For tcp_prot in getorigdst */
#include <linux/icmp.h>
#include <linux/udp.h>
#include <linux/jhash.h>

#include <linux/netfilter_ipv4.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_protocol.h>
#include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_l3proto.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <linux/netfilter_ipv4/ipt_cone.h>

#ifdef HNDCTF
#include <linux/if.h>
#include <linux/if_vlan.h>
#include <typedefs.h>
#include <osl.h>
#include <ctf/hndctf.h>

#define NFC_CTF_ENABLED (1 << 31)
#endif /* HNDCTF */

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

static DEFINE_RWLOCK(nf_nat_lock);

static struct nf_conntrack_l3proto *l3proto = NULL;

/* Calculated at init based on memory size */
static unsigned int nf_nat_htable_size;

static struct list_head *bysource;

#define MAX_IP_NAT_PROTO 256
static struct nf_nat_protocol *nf_nat_protos[MAX_IP_NAT_PROTO];

static inline struct nf_nat_protocol *
__nf_nat_proto_find(u_int8_t protonum)
{
        return rcu_dereference(nf_nat_protos[protonum]);
}

struct nf_nat_protocol *
nf_nat_proto_find_get(u_int8_t protonum)
{
        struct nf_nat_protocol *p;

        rcu_read_lock();
        p = __nf_nat_proto_find(protonum);
        if (!try_module_get(p->me))
                p = &nf_nat_unknown_protocol;
        rcu_read_unlock();

        return p;
}
EXPORT_SYMBOL_GPL(nf_nat_proto_find_get);

void
nf_nat_proto_put(struct nf_nat_protocol *p)
{
        module_put(p->me);
}
EXPORT_SYMBOL_GPL(nf_nat_proto_put);

/* We keep an extra hash for each conntrack, for fast searching. */
static inline unsigned int
hash_by_src(const struct nf_conntrack_tuple *tuple)
{
        unsigned int hash;

        /* Original src, to ensure we map it consistently if poss. */
        hash = jhash_3words((__force u32)tuple->src.u3.ip,
                            (__force u32)tuple->src.u.all,
                            tuple->dst.protonum, 0);
        return ((u64)hash * nf_nat_htable_size) >> 32;
}

#ifdef HNDCTF
extern int ipv4_conntrack_fastnat;

bool
ip_conntrack_is_ipc_allowed(struct sk_buff *skb, u_int32_t hooknum)
{
        struct net_device *dev;

        if (!ipv4_conntrack_fastnat || !CTF_ENAB(kcih))
                return FALSE;

        if (hooknum == NF_IP_PRE_ROUTING || hooknum == NF_IP_POST_ROUTING) {
                dev = skb->dev;
                if (dev->priv_flags & IFF_802_1Q_VLAN)
                        dev = VLAN_DEV_INFO(dev)->real_dev;

                /* Add ipc entry if packet is received on ctf enabled interface
                 * and the packet is not a defrag'd one.
                 */
                if (ctf_isenabled(kcih, dev) && (skb->len <= dev->mtu))
                        skb->nfcache |= NFC_CTF_ENABLED;
        }

        /* Add the cache entries only if the device has registered and
         * enabled ctf.
         */
        if (skb->nfcache & NFC_CTF_ENABLED)
                return TRUE;

        return FALSE;
}
#ifdef CONFIG_BCM_NAT_MODULE
EXPORT_SYMBOL(ip_conntrack_is_ipc_allowed);
#endif

void
ip_conntrack_ipct_add(struct sk_buff *skb, u_int32_t hooknum,
                      struct nf_conn *ct, enum ip_conntrack_info ci,
                      struct nf_conntrack_tuple *manip)
{
        ctf_ipc_t ipc_entry;
        struct hh_cache *hh;
        struct ethhdr *eth;
        struct iphdr *iph;
        struct tcphdr *tcph;
        u_int32_t daddr;
        struct rtable *rt;
        struct nf_conn_help *help;
        enum ip_conntrack_dir dir;

        if ((skb == NULL) || (ct == NULL))
                return;

        /* Check CTF enabled */
        if (!ip_conntrack_is_ipc_allowed(skb, hooknum))
                return;

        /* We only add cache entires for non-helper connections and at
         * pre or post routing hooks.
         */
        help = nfct_help(ct);
        if ((help && help->helper) || (ct->ctf_flags & CTF_FLAGS_EXCLUDED) ||
            ((hooknum != NF_IP_PRE_ROUTING) && (hooknum != NF_IP_POST_ROUTING)))
                return;

        /* Add ipc entries for connections in established state only */
        if ((ci != IP_CT_ESTABLISHED) && (ci != (IP_CT_ESTABLISHED+IP_CT_IS_REPLY)))
                return;

        iph = ip_hdr(skb);
        if (iph->version != 4 ||
            (iph->protocol != IPPROTO_TCP && iph->protocol != IPPROTO_UDP))
                return;
        
        if (iph->protocol == IPPROTO_TCP &&
            ct->proto.tcp.state >= TCP_CONNTRACK_FIN_WAIT &&
            ct->proto.tcp.state <= TCP_CONNTRACK_TIME_WAIT)
                return;

        dir = CTINFO2DIR(ci);
        if (ct->ctf_flags & (1 << dir))
                return;

        /* Do route lookup for alias address if we are doing DNAT in this
         * direction.
         */
        daddr = iph->daddr;
        if ((manip != NULL) && (HOOK2MANIP(hooknum) == IP_NAT_MANIP_DST))
                daddr = manip->dst.u3.ip; 

        /* Find the destination interface */
        if (skb->dst == NULL)
                ip_route_input(skb, daddr, iph->saddr, iph->tos, skb->dev);

        /* Ensure the packet belongs to a forwarding connection and it is
         * destined to an unicast address.
         */
        rt = (struct rtable *)skb->dst;
        if ((rt == NULL) || (rt->u.dst.input != ip_forward) ||
            (rt->rt_type != RTN_UNICAST) || (rt->u.dst.neighbour == NULL) ||
            ((rt->u.dst.neighbour->nud_state &
             (NUD_PERMANENT|NUD_REACHABLE|NUD_STALE|NUD_DELAY|NUD_PROBE)) == 0))
                return;
        
        memset(&ipc_entry, 0, sizeof(ipc_entry));

        /* Init the neighboring sender address */
        memcpy(ipc_entry.sa.octet, eth_hdr(skb)->h_source, ETH_ALEN);

        /* If the packet is received on a bridge device then save
         * the bridge cache entry pointer in the ip cache entry.
         * This will be referenced in the data path to update the
         * live counter of brc entry whenever a received packet
         * matches corresponding ipc entry matches.
         */
        if ((skb->dev != NULL) && ctf_isbridge(kcih, skb->dev))
                ipc_entry.brcp = ctf_brc_lkup(kcih, eth_hdr(skb)->h_source);

        hh = skb->dst->hh;
        if (hh != NULL) {
                eth = (struct ethhdr *)(((unsigned char *)hh->hh_data) + 2);
                memcpy(ipc_entry.dhost.octet, eth->h_dest, ETH_ALEN);
                memcpy(ipc_entry.shost.octet, eth->h_source, ETH_ALEN);
        } else {
                memcpy(ipc_entry.dhost.octet, rt->u.dst.neighbour->ha, ETH_ALEN);
                memcpy(ipc_entry.shost.octet, skb->dst->dev->dev_addr, ETH_ALEN);
        }

        tcph = ((struct tcphdr *)(((__u8 *)iph) + (iph->ihl << 2)));

        /* Add ctf ipc entry for this direction */
        ipc_entry.tuple.sip = iph->saddr;
        ipc_entry.tuple.dip = iph->daddr;
        ipc_entry.tuple.proto = iph->protocol;
        ipc_entry.tuple.sp = tcph->source;
        ipc_entry.tuple.dp = tcph->dest;

        ipc_entry.next = NULL;

        /* For vlan interfaces fill the vlan id and the tag/untag actions */
        if (skb->dst->dev->priv_flags & IFF_802_1Q_VLAN) {
                ipc_entry.txif = (void *)(VLAN_DEV_INFO(skb->dst->dev)->real_dev);
                ipc_entry.vid = VLAN_DEV_INFO(skb->dst->dev)->vlan_id;
                ipc_entry.action = ((VLAN_DEV_INFO(skb->dst->dev)->flags & 1) ?
                                    CTF_ACTION_TAG : CTF_ACTION_UNTAG);
        } else {
                ipc_entry.txif = skb->dst->dev;
                ipc_entry.action = CTF_ACTION_UNTAG;
        }

        /* Update the manip ip and port */
        if (manip != NULL) {
                if (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC) {
                        ipc_entry.nat.ip = manip->src.u3.ip;
                        ipc_entry.nat.port = manip->src.u.tcp.port;
                        ipc_entry.action |= CTF_ACTION_SNAT;
                } else {
                        ipc_entry.nat.ip = manip->dst.u3.ip;
                        ipc_entry.nat.port = manip->dst.u.tcp.port;
                        ipc_entry.action |= CTF_ACTION_DNAT;
                }
        }

        /* Do bridge cache lookup to determine outgoing interface
         * and any vlan tagging actions if needed.
         */
        if (ctf_isbridge(kcih, ipc_entry.txif)) {
                ctf_brc_t *brcp;

                brcp = ctf_brc_lkup(kcih, ipc_entry.dhost.octet);

                if (brcp == NULL)
                        return;
                else {
                        ipc_entry.action |= brcp->action;
                        ipc_entry.txif = brcp->txifp;
                        ipc_entry.vid = brcp->vid;
                }
        }

#ifdef DEBUG
        printk("%s: Adding ipc entry for [%d]%u.%u.%u.%u:%u - %u.%u.%u.%u:%u\n", __FUNCTION__,
                        ipc_entry.tuple.proto, 
                        NIPQUAD(ipc_entry.tuple.sip), ntohs(ipc_entry.tuple.sp), 
                        NIPQUAD(ipc_entry.tuple.dip), ntohs(ipc_entry.tuple.dp)); 
        printk("sa %02x:%02x:%02x:%02x:%02x:%02x\n",
                        ipc_entry.shost.octet[0], ipc_entry.shost.octet[1],
                        ipc_entry.shost.octet[2], ipc_entry.shost.octet[3],
                        ipc_entry.shost.octet[4], ipc_entry.shost.octet[5]);
        printk("da %02x:%02x:%02x:%02x:%02x:%02x\n",
                        ipc_entry.dhost.octet[0], ipc_entry.dhost.octet[1],
                        ipc_entry.dhost.octet[2], ipc_entry.dhost.octet[3],
                        ipc_entry.dhost.octet[4], ipc_entry.dhost.octet[5]);
        printk("[%d] vid: %d action %x\n", hooknum, ipc_entry.vid, ipc_entry.action);
        if (manip != NULL)
                printk("manip_ip: %u.%u.%u.%u manip_port %u\n",
                        NIPQUAD(ipc_entry.nat.ip), ntohs(ipc_entry.nat.port));
        printk("txif: %s\n", ((struct net_device *)ipc_entry.txif)->name);
#endif

        ctf_ipc_add(kcih, &ipc_entry);

        /* Update the attributes flag to indicate a CTF conn */
        ct->ctf_flags |= (CTF_FLAGS_CACHED | (1 << dir));

}
#ifdef CONFIG_BCM_NAT_MODULE
EXPORT_SYMBOL(ip_conntrack_ipct_add);
#endif

int
ip_conntrack_ipct_delete(struct nf_conn *ct, int ct_timeout)
{
        ctf_ipc_t *ipct;
        struct nf_conntrack_tuple *orig, *repl;

        if (!CTF_ENAB(kcih))
                return (0);

        orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;

        if ((orig->dst.protonum != IPPROTO_TCP) && (orig->dst.protonum != IPPROTO_UDP))
                return (0);

        repl = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;

        /* If the refresh counter of ipc entry is non zero, it indicates
         * that the packet transfer is active and we should not delete
         * the conntrack entry.
         */
        if (ct_timeout) {
                ipct = ctf_ipc_lkup(kcih, orig->src.u3.ip, orig->dst.u3.ip,
                                    orig->dst.protonum, orig->src.u.tcp.port,
                                    orig->dst.u.tcp.port);

                /* Postpone the deletion of ct entry if there are frames
                 * flowing in this direction.
                 */
                if ((ipct != NULL) && (ipct->live > 0)) {
                        ipct->live = 0;
                        ct->timeout.expires = jiffies + ct->expire_jiffies;
                        add_timer(&ct->timeout);
                        return (-1);
                }

                ipct = ctf_ipc_lkup(kcih, repl->src.u3.ip, repl->dst.u3.ip,
                                    repl->dst.protonum, repl->src.u.tcp.port,
                                    repl->dst.u.tcp.port);

                if ((ipct != NULL) && (ipct->live > 0)) {
                        ipct->live = 0;
                        ct->timeout.expires = jiffies + ct->expire_jiffies;
                        add_timer(&ct->timeout);
                        return (-1);
                }
        }

        /* If there are no packets over this connection for timeout period
         * delete the entries.
         */
        ctf_ipc_delete(kcih, orig->src.u3.ip, orig->dst.u3.ip, orig->dst.protonum,
                       orig->src.u.tcp.port, orig->dst.u.tcp.port);

        ctf_ipc_delete(kcih, repl->src.u3.ip, repl->dst.u3.ip, repl->dst.protonum,
                       repl->src.u.tcp.port, repl->dst.u.tcp.port);

#ifdef DEBUG
        printk("%s: Deleting the tuple %x %x %d %d %d\n",
               __FUNCTION__, orig->src.u3.ip, orig->dst.u3.ip, orig->dst.protonum,
               orig->src.u.tcp.port, orig->dst.u.tcp.port);
        printk("%s: Deleting the tuple %x %x %d %d %d\n",
               __FUNCTION__, repl->dst.u3.ip, repl->src.u3.ip, repl->dst.protonum,
               repl->dst.u.tcp.port, repl->src.u.tcp.port);
#endif

        return (0);
}
#endif /* HNDCTF */

/* Noone using conntrack by the time this called. */
static void nf_nat_cleanup_conntrack(struct nf_conn *conn)
{
        struct nf_conn_nat *nat;
        if (!(conn->status & IPS_NAT_DONE_MASK))
                return;

        nat = nfct_nat(conn);
        write_lock_bh(&nf_nat_lock);
        list_del(&nat->info.bysource);
        write_unlock_bh(&nf_nat_lock);

        /* Detach from cone list */
        ipt_cone_cleanup_conntrack(nat);
}

/* Is this tuple already taken? (not by us) */
int
nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
                  const struct nf_conn *ignored_conntrack)
{
        /* Conntrack tracking doesn't keep track of outgoing tuples; only
           incoming ones.  NAT means they don't have a fixed mapping,
           so we invert the tuple and look for the incoming reply.

           We could keep a separate hash if this proves too slow. */
        struct nf_conntrack_tuple reply;

        nf_ct_invert_tuplepr(&reply, tuple);
        return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
}
EXPORT_SYMBOL(nf_nat_used_tuple);

/* If we source map this tuple so reply looks like reply_tuple, will
 * that meet the constraints of range. */
static int
in_range(const struct nf_conntrack_tuple *tuple,
         const struct nf_nat_range *range)
{
        struct nf_nat_protocol *proto;
        int ret = 0;

        /* If we are supposed to map IPs, then we must be in the
           range specified, otherwise let this drag us onto a new src IP. */
        if (range->flags & IP_NAT_RANGE_MAP_IPS) {
                if (ntohl(tuple->src.u3.ip) < ntohl(range->min_ip) ||
                    ntohl(tuple->src.u3.ip) > ntohl(range->max_ip))
                        return 0;
        }

        rcu_read_lock();
        proto = __nf_nat_proto_find(tuple->dst.protonum);
        if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) ||
            proto->in_range(tuple, IP_NAT_MANIP_SRC,
                            &range->min, &range->max))
                ret = 1;
        rcu_read_unlock();

        return ret;
}

static inline int
same_src(const struct nf_conn *ct,
         const struct nf_conntrack_tuple *tuple)
{
        const struct nf_conntrack_tuple *t;

        t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
        return (t->dst.protonum == tuple->dst.protonum &&
                t->src.u3.ip == tuple->src.u3.ip &&
                t->src.u.all == tuple->src.u.all);
}

/* Only called for SRC manip */
static int
find_appropriate_src(const struct nf_conntrack_tuple *tuple,
                     struct nf_conntrack_tuple *result,
                     const struct nf_nat_range *range)
{
        unsigned int h = hash_by_src(tuple);
        struct nf_conn_nat *nat;
        struct nf_conn *ct;

        read_lock_bh(&nf_nat_lock);
        list_for_each_entry(nat, &bysource[h], info.bysource) {
                ct = (struct nf_conn *)((char *)nat - offsetof(struct nf_conn, data));
                if (same_src(ct, tuple)) {
                        /* Copy source part from reply tuple. */
                        nf_ct_invert_tuplepr(result,
                                       &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
                        result->dst = tuple->dst;

                        if (in_range(result, range)) {
                                read_unlock_bh(&nf_nat_lock);
                                return 1;
                        }
                }
        }
        read_unlock_bh(&nf_nat_lock);
        return 0;
}

/* For [FUTURE] fragmentation handling, we want the least-used
   src-ip/dst-ip/proto triple.  Fairness doesn't come into it.  Thus
   if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
   1-65535, we don't do pro-rata allocation based on ports; we choose
   the ip with the lowest src-ip/dst-ip/proto usage.
*/
static void
find_best_ips_proto(struct nf_conntrack_tuple *tuple,
                    const struct nf_nat_range *range,
                    const struct nf_conn *ct,
                    enum nf_nat_manip_type maniptype)
{
        __be32 *var_ipp;
        /* Host order */
        u_int32_t minip, maxip, j;

        /* No IP mapping?  Do nothing. */
        if (!(range->flags & IP_NAT_RANGE_MAP_IPS))
                return;

        if (maniptype == IP_NAT_MANIP_SRC)
                var_ipp = &tuple->src.u3.ip;
        else
                var_ipp = &tuple->dst.u3.ip;

        /* Fast path: only one choice. */
        if (range->min_ip == range->max_ip) {
                *var_ipp = range->min_ip;
                return;
        }

        /* Hashing source and destination IPs gives a fairly even
         * spread in practice (if there are a small number of IPs
         * involved, there usually aren't that many connections
         * anyway).  The consistency means that servers see the same
         * client coming from the same IP (some Internet Banking sites
         * like this), even across reboots. */
        minip = ntohl(range->min_ip);
        maxip = ntohl(range->max_ip);
        j = jhash_2words((__force u32)tuple->src.u3.ip,
                         (__force u32)tuple->dst.u3.ip, 0);
        j = ((u64)j * (maxip - minip + 1)) >> 32;
        *var_ipp = htonl(minip + j);
}

/* Manipulate the tuple into the range given.  For NF_IP_POST_ROUTING,
 * we change the source to map into the range.  For NF_IP_PRE_ROUTING
 * and NF_IP_LOCAL_OUT, we change the destination to map into the
 * range.  It might not be possible to get a unique tuple, but we try.
 * At worst (or if we race), we will end up with a final duplicate in
 * __ip_conntrack_confirm and drop the packet. */
static void
get_unique_tuple(struct nf_conntrack_tuple *tuple,
                 const struct nf_conntrack_tuple *orig_tuple,
                 const struct nf_nat_range *range,
                 struct nf_conn *ct,
                 enum nf_nat_manip_type maniptype)
{
        struct nf_nat_protocol *proto;

        /* 1) If this srcip/proto/src-proto-part is currently mapped,
           and that same mapping gives a unique tuple within the given
           range, use that.

           This is only required for source (ie. NAT/masq) mappings.
           So far, we don't do local source mappings, so multiple
           manips not an issue.  */
        if (maniptype == IP_NAT_MANIP_SRC) {
                if (find_appropriate_src(orig_tuple, tuple, range)) {
                        DEBUGP("get_unique_tuple: Found current src map\n");
                        if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM))
                                if (!nf_nat_used_tuple(tuple, ct))
                                        return;
                }
        }

        /* 2) Select the least-used IP/proto combination in the given
           range. */
        *tuple = *orig_tuple;
        find_best_ips_proto(tuple, range, ct, maniptype);

        /* 3) The per-protocol part of the manip is made to map into
           the range to make a unique tuple. */

        rcu_read_lock();
        proto = __nf_nat_proto_find(orig_tuple->dst.protonum);

        /* Only bother mapping if it's not already in range and unique */
        if (!(range->flags & IP_NAT_RANGE_PROTO_RANDOM)) {
                if (range->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
                        if (proto->in_range(tuple, maniptype, &range->min,
                                            &range->max) &&
                            (range->min.all == range->max.all ||
                             !nf_nat_used_tuple(tuple, ct)))
                                goto out;
                } else if (!nf_nat_used_tuple(tuple, ct)) {
                        goto out;
                }
        }

        /* Last change: get protocol to try to obtain unique tuple. */
        proto->unique_tuple(tuple, range, maniptype, ct);
out:
        rcu_read_unlock();
}

unsigned int
nf_nat_setup_info(struct nf_conn *ct,
                  const struct nf_nat_range *range,
                  unsigned int hooknum)
{
        struct nf_conntrack_tuple curr_tuple, new_tuple;
        struct nf_conn_nat *nat = nfct_nat(ct);
        struct nf_nat_info *info = &nat->info;
        int have_to_hash = !(ct->status & IPS_NAT_DONE_MASK);
        enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum);

        NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING ||
                     hooknum == NF_IP_POST_ROUTING ||
                     hooknum == NF_IP_LOCAL_IN ||
                     hooknum == NF_IP_LOCAL_OUT);
        BUG_ON(nf_nat_initialized(ct, maniptype));

        /* What we've got will look like inverse of reply. Normally
           this is what is in the conntrack, except for prior
           manipulations (future optimization: if num_manips == 0,
           orig_tp =
           conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple) */
        nf_ct_invert_tuplepr(&curr_tuple,
                             &ct->tuplehash[IP_CT_DIR_REPLY].tuple);

        get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);

        if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
                struct nf_conntrack_tuple reply;

                /* Alter conntrack table so will recognize replies. */
                nf_ct_invert_tuplepr(&reply, &new_tuple);
                nf_conntrack_alter_reply(ct, &reply);

                /* Non-atomic: we own this at the moment. */
                if (maniptype == IP_NAT_MANIP_SRC)
                        ct->status |= IPS_SRC_NAT;
                else
                        ct->status |= IPS_DST_NAT;
        }

        /* Place in source hash if this is the first time. */
        if (have_to_hash) {
                unsigned int srchash;

                srchash = hash_by_src(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
                write_lock_bh(&nf_nat_lock);
                list_add(&info->bysource, &bysource[srchash]);
                write_unlock_bh(&nf_nat_lock);
        }

        /* It's done. */
        if (maniptype == IP_NAT_MANIP_DST)
                set_bit(IPS_DST_NAT_DONE_BIT, &ct->status);
        else
                set_bit(IPS_SRC_NAT_DONE_BIT, &ct->status);

        return NF_ACCEPT;
}
EXPORT_SYMBOL(nf_nat_setup_info);

/* Returns true if succeeded. */
static int
manip_pkt(u_int16_t proto,
          struct sk_buff *skb,
          unsigned int iphdroff,
          const struct nf_conntrack_tuple *target,
          enum nf_nat_manip_type maniptype)
{
        struct iphdr *iph;
        struct nf_nat_protocol *p;

        if (!skb_make_writable(skb, iphdroff + sizeof(*iph)))
                return 0;

        iph = (void *)skb->data + iphdroff;

        /* Manipulate protcol part. */

        /* rcu_read_lock()ed by nf_hook_slow */
        p = __nf_nat_proto_find(proto);
        if (!p->manip_pkt(skb, iphdroff, target, maniptype))
                return 0;

        iph = (void *)skb->data + iphdroff;

        if (maniptype == IP_NAT_MANIP_SRC) {
                nf_csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
                iph->saddr = target->src.u3.ip;
        } else {
                nf_csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
                iph->daddr = target->dst.u3.ip;
        }
        return 1;
}

#if defined(CONFIG_BCM_NAT) || defined(CONFIG_BCM_NAT_MODULE)
#ifndef CONFIG_BCM_NAT_MODULE
inline
#endif
int bcm_manip_pkt(u_int16_t proto,
          struct sk_buff *skb,
          unsigned int iphdroff,
          const struct nf_conntrack_tuple *target,
          enum nf_nat_manip_type maniptype)
{
        return manip_pkt(proto, skb, iphdroff, target, maniptype);
}
#ifdef CONFIG_BCM_NAT_MODULE
EXPORT_SYMBOL(bcm_manip_pkt);
#endif
#endif

/* Do packet manipulations according to nf_nat_setup_info. */
unsigned int nf_nat_packet(struct nf_conn *ct,
                           enum ip_conntrack_info ctinfo,
                           unsigned int hooknum,
                           struct sk_buff *skb)
{
        enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
        unsigned long statusbit;
        enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);

        if (mtype == IP_NAT_MANIP_SRC)
                statusbit = IPS_SRC_NAT;
        else
                statusbit = IPS_DST_NAT;

        /* Invert if this is reply dir. */
        if (dir == IP_CT_DIR_REPLY)
                statusbit ^= IPS_NAT_MASK;

        /* Non-atomic: these bits don't change. */
        if (ct->status & statusbit) {
                struct nf_conntrack_tuple target;

                /* We are aiming to look like inverse of other direction. */
                nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
#ifdef HNDCTF
                ip_conntrack_ipct_add(skb, hooknum, ct, ctinfo, &target);
#endif /* HNDCTF */
                if (!manip_pkt(target.dst.protonum, skb, 0, &target, mtype))
                        return NF_DROP;
        } else {
#ifdef HNDCTF
#endif /* HNDCTF */
        }

        return NF_ACCEPT;
}
EXPORT_SYMBOL_GPL(nf_nat_packet);

/* Dir is direction ICMP is coming from (opposite to packet it contains) */
int nf_nat_icmp_reply_translation(struct nf_conn *ct,
                                  enum ip_conntrack_info ctinfo,
                                  unsigned int hooknum,
                                  struct sk_buff *skb)
{
        struct {
                struct icmphdr icmp;
                struct iphdr ip;
        } *inside;
        struct nf_conntrack_l4proto *l4proto;
        struct nf_conntrack_tuple inner, target;
        int hdrlen = ip_hdrlen(skb);
        enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
        unsigned long statusbit;
        enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);

        if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
                return 0;

        inside = (void *)skb->data + hdrlen;

        /* We're actually going to mangle it beyond trivial checksum
           adjustment, so make sure the current checksum is correct. */
        if (nf_ip_checksum(skb, hooknum, hdrlen, 0))
                return 0;

        /* Must be RELATED */
        NF_CT_ASSERT(skb->nfctinfo == IP_CT_RELATED ||
                     skb->nfctinfo == IP_CT_RELATED+IP_CT_IS_REPLY);

        /* Redirects on non-null nats must be dropped, else they'll
           start talking to each other without our translation, and be
           confused... --RR */
        if (inside->icmp.type == ICMP_REDIRECT) {
                /* If NAT isn't finished, assume it and drop. */
                if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
                        return 0;

                if (ct->status & IPS_NAT_MASK)
                        return 0;
        }

        DEBUGP("icmp_reply_translation: translating error %p manp %u dir %s\n",
               skb, manip, dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY");

        /* rcu_read_lock()ed by nf_hook_slow */
        l4proto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);

        if (!nf_ct_get_tuple(skb, hdrlen + sizeof(struct icmphdr),
                             (hdrlen +
                              sizeof(struct icmphdr) + inside->ip.ihl * 4),
                             (u_int16_t)AF_INET, inside->ip.protocol,
                             &inner, l3proto, l4proto))
                return 0;

        /* Change inner back to look like incoming packet.  We do the
           opposite manip on this hook to normal, because it might not
           pass all hooks (locally-generated ICMP).  Consider incoming
           packet: PREROUTING (DST manip), routing produces ICMP, goes
           through POSTROUTING (which must correct the DST manip). */
        if (!manip_pkt(inside->ip.protocol, skb, hdrlen + sizeof(inside->icmp),
                       &ct->tuplehash[!dir].tuple, !manip))
                return 0;

        if (skb->ip_summed != CHECKSUM_PARTIAL) {
                /* Reloading "inside" here since manip_pkt inner. */
                inside = (void *)skb->data + hdrlen;
                inside->icmp.checksum = 0;
                inside->icmp.checksum =
                        csum_fold(skb_checksum(skb, hdrlen,
                                               skb->len - hdrlen, 0));
        }

        /* Change outer to look the reply to an incoming packet
         * (proto 0 means don't invert per-proto part). */
        if (manip == IP_NAT_MANIP_SRC)
                statusbit = IPS_SRC_NAT;
        else
                statusbit = IPS_DST_NAT;

        /* Invert if this is reply dir. */
        if (dir == IP_CT_DIR_REPLY)
                statusbit ^= IPS_NAT_MASK;

        if (ct->status & statusbit) {
                nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
                if (!manip_pkt(0, skb, 0, &target, manip))
                        return 0;
        }

        return 1;
}
EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation);

/* Protocol registration. */
int nf_nat_protocol_register(struct nf_nat_protocol *proto)
{
        int ret = 0;

        write_lock_bh(&nf_nat_lock);
        if (nf_nat_protos[proto->protonum] != &nf_nat_unknown_protocol) {
                ret = -EBUSY;
                goto out;
        }
        rcu_assign_pointer(nf_nat_protos[proto->protonum], proto);
 out:
        write_unlock_bh(&nf_nat_lock);
        return ret;
}
EXPORT_SYMBOL(nf_nat_protocol_register);

/* Noone stores the protocol anywhere; simply delete it. */
void nf_nat_protocol_unregister(struct nf_nat_protocol *proto)
{
        write_lock_bh(&nf_nat_lock);
        rcu_assign_pointer(nf_nat_protos[proto->protonum],
                           &nf_nat_unknown_protocol);
        write_unlock_bh(&nf_nat_lock);
        synchronize_rcu();
}
EXPORT_SYMBOL(nf_nat_protocol_unregister);

#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
int
nf_nat_port_range_to_nfattr(struct sk_buff *skb,
                            const struct nf_nat_range *range)
{
        NFA_PUT(skb, CTA_PROTONAT_PORT_MIN, sizeof(__be16),
                &range->min.tcp.port);
        NFA_PUT(skb, CTA_PROTONAT_PORT_MAX, sizeof(__be16),
                &range->max.tcp.port);

        return 0;

nfattr_failure:
        return -1;
}
EXPORT_SYMBOL_GPL(nf_nat_port_nfattr_to_range);

int
nf_nat_port_nfattr_to_range(struct nfattr *tb[], struct nf_nat_range *range)
{
        int ret = 0;

        /* we have to return whether we actually parsed something or not */

        if (tb[CTA_PROTONAT_PORT_MIN-1]) {
                ret = 1;
                range->min.tcp.port =
                        *(__be16 *)NFA_DATA(tb[CTA_PROTONAT_PORT_MIN-1]);
        }

        if (!tb[CTA_PROTONAT_PORT_MAX-1]) {
                if (ret)
                        range->max.tcp.port = range->min.tcp.port;
        } else {
                ret = 1;
                range->max.tcp.port =
                        *(__be16 *)NFA_DATA(tb[CTA_PROTONAT_PORT_MAX-1]);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(nf_nat_port_range_to_nfattr);
#endif

static int __init nf_nat_init(void)
{
        size_t i;

        /* Leave them the same for the moment. */
        nf_nat_htable_size = nf_conntrack_htable_size;

        /* One vmalloc for both hash tables */
        bysource = vmalloc(sizeof(struct list_head) * nf_nat_htable_size);
        if (!bysource)
                return -ENOMEM;

        /* Sew in builtin protocols. */
        write_lock_bh(&nf_nat_lock);
        for (i = 0; i < MAX_IP_NAT_PROTO; i++)
                rcu_assign_pointer(nf_nat_protos[i], &nf_nat_unknown_protocol);
        rcu_assign_pointer(nf_nat_protos[IPPROTO_TCP], &nf_nat_protocol_tcp);
        rcu_assign_pointer(nf_nat_protos[IPPROTO_UDP], &nf_nat_protocol_udp);
        rcu_assign_pointer(nf_nat_protos[IPPROTO_ICMP], &nf_nat_protocol_icmp);
        write_unlock_bh(&nf_nat_lock);

        for (i = 0; i < nf_nat_htable_size; i++) {
                INIT_LIST_HEAD(&bysource[i]);
        }

        /* FIXME: Man, this is a hack.  <SIGH> */
        NF_CT_ASSERT(rcu_dereference(nf_conntrack_destroyed) == NULL);
        rcu_assign_pointer(nf_conntrack_destroyed, nf_nat_cleanup_conntrack);

        NF_CT_ASSERT(rcu_dereference(nf_ct_nat_offset) == NULL);
        rcu_assign_pointer(nf_ct_nat_offset, nf_nat_get_offset);

        /* Initialize fake conntrack so that NAT will skip it */
        nf_conntrack_untracked.status |= IPS_NAT_DONE_MASK;

        l3proto = nf_ct_l3proto_find_get((u_int16_t)AF_INET);
        return 0;
}

/* Clear NAT section of all conntracks, in case we're loaded again. */
static int clean_nat(struct nf_conn *i, void *data)
{
        struct nf_conn_nat *nat = nfct_nat(i);

        if (!nat)
                return 0;
        memset(nat, 0, sizeof(*nat));
        i->status &= ~(IPS_NAT_MASK | IPS_NAT_DONE_MASK | IPS_SEQ_ADJUST);
        return 0;
}

static void __exit nf_nat_cleanup(void)
{
        nf_ct_iterate_cleanup(&clean_nat, NULL);
        rcu_assign_pointer(nf_conntrack_destroyed, NULL);
        rcu_assign_pointer(nf_ct_nat_offset, NULL);
        synchronize_rcu();
        vfree(bysource);
        nf_ct_l3proto_put(l3proto);
}

MODULE_LICENSE("GPL");

module_init(nf_nat_init);
module_exit(nf_nat_cleanup);