335 lines
7.2 KiB
C
335 lines
7.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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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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#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/pkt_cls.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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static struct tc_action_ops act_nat_ops;
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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 net *net, struct nlattr *nla, struct nlattr *est,
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struct tc_action **a, struct tcf_proto *tp,
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u32 flags, struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
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bool bind = flags & TCA_ACT_FLAGS_BIND;
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struct nlattr *tb[TCA_NAT_MAX + 1];
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struct tcf_chain *goto_ch = NULL;
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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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u32 index;
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if (nla == NULL)
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return -EINVAL;
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err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, nat_policy,
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NULL);
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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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index = parm->index;
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err = tcf_idr_check_alloc(tn, &index, a, bind);
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if (!err) {
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ret = tcf_idr_create(tn, index, est, a,
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&act_nat_ops, bind, false, flags);
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if (ret) {
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tcf_idr_cleanup(tn, index);
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return ret;
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}
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ret = ACT_P_CREATED;
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} else if (err > 0) {
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if (bind)
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return 0;
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if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
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tcf_idr_release(*a, bind);
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return -EEXIST;
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}
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} else {
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return err;
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}
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err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
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if (err < 0)
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goto release_idr;
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p = to_tcf_nat(*a);
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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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goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
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spin_unlock_bh(&p->tcf_lock);
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if (goto_ch)
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tcf_chain_put_by_act(goto_ch);
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return ret;
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release_idr:
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tcf_idr_release(*a, bind);
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return err;
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}
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static int tcf_nat_act(struct sk_buff *skb, const struct tc_action *a,
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struct tcf_result *res)
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{
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struct tcf_nat *p = to_tcf_nat(a);
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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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int noff;
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spin_lock(&p->tcf_lock);
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tcf_lastuse_update(&p->tcf_tm);
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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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bstats_update(&p->tcf_bstats, skb);
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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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noff = skb_network_offset(skb);
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if (!pskb_may_pull(skb, sizeof(*iph) + noff))
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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_try_make_writable(skb, sizeof(*iph) + noff))
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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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} else if ((iph->frag_off & htons(IP_OFFSET)) ||
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iph->protocol != IPPROTO_ICMP) {
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goto out;
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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) + noff) ||
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skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
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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,
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true);
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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) + noff) ||
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skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
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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, true);
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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) + noff))
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goto drop;
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icmph = (void *)(skb_network_header(skb) + ihl);
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if (!icmp_is_err(icmph->type))
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break;
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if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
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noff))
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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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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_try_make_writable(skb, ihl + sizeof(*icmph) +
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sizeof(*iph) + noff))
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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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false);
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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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out:
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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 = to_tcf_nat(a);
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struct tc_nat opt = {
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.index = p->tcf_index,
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.refcnt = refcount_read(&p->tcf_refcnt) - ref,
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.bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
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};
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struct tcf_t t;
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spin_lock_bh(&p->tcf_lock);
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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.action = p->tcf_action;
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if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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tcf_tm_dump(&t, &p->tcf_tm);
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if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
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goto nla_put_failure;
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spin_unlock_bh(&p->tcf_lock);
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return skb->len;
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nla_put_failure:
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spin_unlock_bh(&p->tcf_lock);
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nlmsg_trim(skb, b);
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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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.id = TCA_ID_NAT,
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.owner = THIS_MODULE,
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.act = tcf_nat_act,
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.dump = tcf_nat_dump,
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.init = tcf_nat_init,
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.size = sizeof(struct tcf_nat),
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};
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static __net_init int nat_init_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
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return tc_action_net_init(net, tn, &act_nat_ops);
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}
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static void __net_exit nat_exit_net(struct list_head *net_list)
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{
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tc_action_net_exit(net_list, act_nat_ops.net_id);
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}
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static struct pernet_operations nat_net_ops = {
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.init = nat_init_net,
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.exit_batch = nat_exit_net,
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.id = &act_nat_ops.net_id,
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.size = sizeof(struct tc_action_net),
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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, &nat_net_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, &nat_net_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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