330 lines
7.1 KiB
C
330 lines
7.1 KiB
C
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/*
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* Stateless NAT actions
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*
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* Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*/
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/netfilter.h>
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#include <linux/rtnetlink.h>
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/string.h>
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#include <linux/tc_act/tc_nat.h>
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#include <net/act_api.h>
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#include <net/icmp.h>
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#include <net/ip.h>
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#include <net/netlink.h>
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#include <net/tc_act/tc_nat.h>
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#include <net/tcp.h>
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#include <net/udp.h>
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#define NAT_TAB_MASK 15
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static struct tcf_common *tcf_nat_ht[NAT_TAB_MASK + 1];
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static u32 nat_idx_gen;
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static DEFINE_RWLOCK(nat_lock);
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static struct tcf_hashinfo nat_hash_info = {
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.htab = tcf_nat_ht,
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.hmask = NAT_TAB_MASK,
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.lock = &nat_lock,
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};
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static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
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[TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
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};
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static int tcf_nat_init(struct nlattr *nla, struct nlattr *est,
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struct tc_action *a, int ovr, int bind)
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{
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struct nlattr *tb[TCA_NAT_MAX + 1];
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struct tc_nat *parm;
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int ret = 0, err;
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struct tcf_nat *p;
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struct tcf_common *pc;
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if (nla == NULL)
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return -EINVAL;
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err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
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if (err < 0)
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return err;
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if (tb[TCA_NAT_PARMS] == NULL)
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return -EINVAL;
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parm = nla_data(tb[TCA_NAT_PARMS]);
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pc = tcf_hash_check(parm->index, a, bind, &nat_hash_info);
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if (!pc) {
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pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
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&nat_idx_gen, &nat_hash_info);
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if (IS_ERR(pc))
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return PTR_ERR(pc);
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p = to_tcf_nat(pc);
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ret = ACT_P_CREATED;
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} else {
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p = to_tcf_nat(pc);
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if (!ovr) {
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tcf_hash_release(pc, bind, &nat_hash_info);
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return -EEXIST;
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}
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}
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spin_lock_bh(&p->tcf_lock);
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p->old_addr = parm->old_addr;
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p->new_addr = parm->new_addr;
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p->mask = parm->mask;
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p->flags = parm->flags;
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p->tcf_action = parm->action;
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spin_unlock_bh(&p->tcf_lock);
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if (ret == ACT_P_CREATED)
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tcf_hash_insert(pc, &nat_hash_info);
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return ret;
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}
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static int tcf_nat_cleanup(struct tc_action *a, int bind)
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{
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struct tcf_nat *p = a->priv;
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return tcf_hash_release(&p->common, bind, &nat_hash_info);
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}
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static int tcf_nat(struct sk_buff *skb, struct tc_action *a,
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struct tcf_result *res)
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{
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struct tcf_nat *p = a->priv;
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struct iphdr *iph;
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__be32 old_addr;
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__be32 new_addr;
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__be32 mask;
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__be32 addr;
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int egress;
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int action;
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int ihl;
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spin_lock(&p->tcf_lock);
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p->tcf_tm.lastuse = jiffies;
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old_addr = p->old_addr;
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new_addr = p->new_addr;
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mask = p->mask;
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egress = p->flags & TCA_NAT_FLAG_EGRESS;
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action = p->tcf_action;
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p->tcf_bstats.bytes += qdisc_pkt_len(skb);
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p->tcf_bstats.packets++;
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spin_unlock(&p->tcf_lock);
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if (unlikely(action == TC_ACT_SHOT))
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goto drop;
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if (!pskb_may_pull(skb, sizeof(*iph)))
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goto drop;
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iph = ip_hdr(skb);
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if (egress)
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addr = iph->saddr;
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else
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addr = iph->daddr;
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if (!((old_addr ^ addr) & mask)) {
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if (skb_cloned(skb) &&
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!skb_clone_writable(skb, sizeof(*iph)) &&
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pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
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goto drop;
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new_addr &= mask;
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new_addr |= addr & ~mask;
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/* Rewrite IP header */
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iph = ip_hdr(skb);
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if (egress)
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iph->saddr = new_addr;
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else
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iph->daddr = new_addr;
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csum_replace4(&iph->check, addr, new_addr);
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}
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ihl = iph->ihl * 4;
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/* It would be nice to share code with stateful NAT. */
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switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
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case IPPROTO_TCP:
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{
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struct tcphdr *tcph;
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if (!pskb_may_pull(skb, ihl + sizeof(*tcph)) ||
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(skb_cloned(skb) &&
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!skb_clone_writable(skb, ihl + sizeof(*tcph)) &&
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pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
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goto drop;
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tcph = (void *)(skb_network_header(skb) + ihl);
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inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1);
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break;
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}
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case IPPROTO_UDP:
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{
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struct udphdr *udph;
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if (!pskb_may_pull(skb, ihl + sizeof(*udph)) ||
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(skb_cloned(skb) &&
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!skb_clone_writable(skb, ihl + sizeof(*udph)) &&
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pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
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goto drop;
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udph = (void *)(skb_network_header(skb) + ihl);
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if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
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inet_proto_csum_replace4(&udph->check, skb, addr,
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new_addr, 1);
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if (!udph->check)
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udph->check = CSUM_MANGLED_0;
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}
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break;
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}
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case IPPROTO_ICMP:
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{
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struct icmphdr *icmph;
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if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph)))
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goto drop;
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icmph = (void *)(skb_network_header(skb) + ihl);
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if ((icmph->type != ICMP_DEST_UNREACH) &&
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(icmph->type != ICMP_TIME_EXCEEDED) &&
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(icmph->type != ICMP_PARAMETERPROB))
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break;
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iph = (void *)(icmph + 1);
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if (egress)
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addr = iph->daddr;
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else
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addr = iph->saddr;
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if ((old_addr ^ addr) & mask)
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break;
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if (skb_cloned(skb) &&
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!skb_clone_writable(skb,
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ihl + sizeof(*icmph) + sizeof(*iph)) &&
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pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
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goto drop;
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icmph = (void *)(skb_network_header(skb) + ihl);
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iph = (void *)(icmph + 1);
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new_addr &= mask;
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new_addr |= addr & ~mask;
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/* XXX Fix up the inner checksums. */
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if (egress)
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iph->daddr = new_addr;
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else
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iph->saddr = new_addr;
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inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
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1);
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break;
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}
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default:
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break;
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}
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return action;
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drop:
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spin_lock(&p->tcf_lock);
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p->tcf_qstats.drops++;
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spin_unlock(&p->tcf_lock);
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return TC_ACT_SHOT;
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}
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static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
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int bind, int ref)
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{
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unsigned char *b = skb_tail_pointer(skb);
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struct tcf_nat *p = a->priv;
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struct tc_nat *opt;
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struct tcf_t t;
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int s;
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s = sizeof(*opt);
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/* netlink spinlocks held above us - must use ATOMIC */
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opt = kzalloc(s, GFP_ATOMIC);
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if (unlikely(!opt))
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return -ENOBUFS;
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opt->old_addr = p->old_addr;
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opt->new_addr = p->new_addr;
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opt->mask = p->mask;
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opt->flags = p->flags;
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opt->index = p->tcf_index;
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opt->action = p->tcf_action;
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opt->refcnt = p->tcf_refcnt - ref;
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opt->bindcnt = p->tcf_bindcnt - bind;
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NLA_PUT(skb, TCA_NAT_PARMS, s, opt);
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t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
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t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
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t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
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NLA_PUT(skb, TCA_NAT_TM, sizeof(t), &t);
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kfree(opt);
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return skb->len;
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nla_put_failure:
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nlmsg_trim(skb, b);
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kfree(opt);
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return -1;
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}
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static struct tc_action_ops act_nat_ops = {
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.kind = "nat",
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.hinfo = &nat_hash_info,
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.type = TCA_ACT_NAT,
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.capab = TCA_CAP_NONE,
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.owner = THIS_MODULE,
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.act = tcf_nat,
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.dump = tcf_nat_dump,
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.cleanup = tcf_nat_cleanup,
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.lookup = tcf_hash_search,
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.init = tcf_nat_init,
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.walk = tcf_generic_walker
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};
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MODULE_DESCRIPTION("Stateless NAT actions");
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MODULE_LICENSE("GPL");
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static int __init nat_init_module(void)
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{
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return tcf_register_action(&act_nat_ops);
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}
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static void __exit nat_cleanup_module(void)
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{
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tcf_unregister_action(&act_nat_ops);
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}
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module_init(nat_init_module);
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module_exit(nat_cleanup_module);
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