473 lines
13 KiB
C
Executable File
473 lines
13 KiB
C
Executable File
/*
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* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Development of IPv6 NAT funded by Astaro.
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*/
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/ipv6.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv6.h>
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#include <net/secure_seq.h>
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#include <net/checksum.h>
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#include <net/ip6_checksum.h>
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#include <net/ip6_route.h>
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#include <net/ipv6.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_nat_core.h>
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#include <net/netfilter/nf_nat_l3proto.h>
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#include <net/netfilter/nf_nat_l4proto.h>
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static const struct nf_nat_l3proto nf_nat_l3proto_ipv6;
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#ifdef CONFIG_XFRM
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static void nf_nat_ipv6_decode_session(struct sk_buff *skb,
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const struct nf_conn *ct,
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enum ip_conntrack_dir dir,
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unsigned long statusbit,
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struct flowi *fl)
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{
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const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
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struct flowi6 *fl6 = &fl->u.ip6;
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if (ct->status & statusbit) {
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fl6->daddr = t->dst.u3.in6;
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if (t->dst.protonum == IPPROTO_TCP ||
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t->dst.protonum == IPPROTO_UDP ||
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t->dst.protonum == IPPROTO_UDPLITE ||
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t->dst.protonum == IPPROTO_DCCP ||
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t->dst.protonum == IPPROTO_SCTP)
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fl6->fl6_dport = t->dst.u.all;
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}
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statusbit ^= IPS_NAT_MASK;
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if (ct->status & statusbit) {
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fl6->saddr = t->src.u3.in6;
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if (t->dst.protonum == IPPROTO_TCP ||
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t->dst.protonum == IPPROTO_UDP ||
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t->dst.protonum == IPPROTO_UDPLITE ||
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t->dst.protonum == IPPROTO_DCCP ||
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t->dst.protonum == IPPROTO_SCTP)
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fl6->fl6_sport = t->src.u.all;
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}
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}
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#endif
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static bool nf_nat_ipv6_in_range(const struct nf_conntrack_tuple *t,
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const struct nf_nat_range *range)
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{
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return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
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ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
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}
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static u32 nf_nat_ipv6_secure_port(const struct nf_conntrack_tuple *t,
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__be16 dport)
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{
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return secure_ipv6_port_ephemeral(t->src.u3.ip6, t->dst.u3.ip6, dport);
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}
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static bool nf_nat_ipv6_manip_pkt(struct sk_buff *skb,
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unsigned int iphdroff,
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const struct nf_nat_l4proto *l4proto,
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const struct nf_conntrack_tuple *target,
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enum nf_nat_manip_type maniptype)
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{
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struct ipv6hdr *ipv6h;
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__be16 frag_off;
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int hdroff;
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u8 nexthdr;
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if (!skb_make_writable(skb, iphdroff + sizeof(*ipv6h)))
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return false;
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ipv6h = (void *)skb->data + iphdroff;
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nexthdr = ipv6h->nexthdr;
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hdroff = ipv6_skip_exthdr(skb, iphdroff + sizeof(*ipv6h),
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&nexthdr, &frag_off);
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if (hdroff < 0)
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goto manip_addr;
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if ((frag_off & htons(~0x7)) == 0 &&
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!l4proto->manip_pkt(skb, &nf_nat_l3proto_ipv6, iphdroff, hdroff,
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target, maniptype))
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return false;
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/* must reload, offset might have changed */
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ipv6h = (void *)skb->data + iphdroff;
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manip_addr:
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if (maniptype == NF_NAT_MANIP_SRC)
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ipv6h->saddr = target->src.u3.in6;
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else
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ipv6h->daddr = target->dst.u3.in6;
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return true;
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}
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static void nf_nat_ipv6_csum_update(struct sk_buff *skb,
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unsigned int iphdroff, __sum16 *check,
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const struct nf_conntrack_tuple *t,
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enum nf_nat_manip_type maniptype)
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{
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const struct ipv6hdr *ipv6h = (struct ipv6hdr *)(skb->data + iphdroff);
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const struct in6_addr *oldip, *newip;
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if (maniptype == NF_NAT_MANIP_SRC) {
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oldip = &ipv6h->saddr;
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newip = &t->src.u3.in6;
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} else {
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oldip = &ipv6h->daddr;
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newip = &t->dst.u3.in6;
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}
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inet_proto_csum_replace16(check, skb, oldip->s6_addr32,
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newip->s6_addr32, true);
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}
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static void nf_nat_ipv6_csum_recalc(struct sk_buff *skb,
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u8 proto, void *data, __sum16 *check,
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int datalen, int oldlen)
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{
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if (skb->ip_summed != CHECKSUM_PARTIAL) {
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const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
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skb->ip_summed = CHECKSUM_PARTIAL;
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skb->csum_start = skb_headroom(skb) + skb_network_offset(skb) +
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(data - (void *)skb->data);
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skb->csum_offset = (void *)check - data;
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*check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
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datalen, proto, 0);
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} else
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inet_proto_csum_replace2(check, skb,
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htons(oldlen), htons(datalen), true);
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}
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#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
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static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
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struct nf_nat_range *range)
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{
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if (tb[CTA_NAT_V6_MINIP]) {
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nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
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sizeof(struct in6_addr));
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range->flags |= NF_NAT_RANGE_MAP_IPS;
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}
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if (tb[CTA_NAT_V6_MAXIP])
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nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
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sizeof(struct in6_addr));
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else
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range->max_addr = range->min_addr;
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return 0;
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}
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#endif
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static const struct nf_nat_l3proto nf_nat_l3proto_ipv6 = {
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.l3proto = NFPROTO_IPV6,
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.secure_port = nf_nat_ipv6_secure_port,
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.in_range = nf_nat_ipv6_in_range,
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.manip_pkt = nf_nat_ipv6_manip_pkt,
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.csum_update = nf_nat_ipv6_csum_update,
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.csum_recalc = nf_nat_ipv6_csum_recalc,
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#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
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.nlattr_to_range = nf_nat_ipv6_nlattr_to_range,
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#endif
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#ifdef CONFIG_XFRM
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.decode_session = nf_nat_ipv6_decode_session,
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#endif
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};
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int nf_nat_icmpv6_reply_translation(struct sk_buff *skb,
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struct nf_conn *ct,
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enum ip_conntrack_info ctinfo,
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unsigned int hooknum,
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unsigned int hdrlen)
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{
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struct {
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struct icmp6hdr icmp6;
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struct ipv6hdr ip6;
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} *inside;
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
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const struct nf_nat_l4proto *l4proto;
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struct nf_conntrack_tuple target;
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unsigned long statusbit;
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WARN_ON(ctinfo != IP_CT_RELATED && ctinfo != IP_CT_RELATED_REPLY);
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if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
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return 0;
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if (nf_ip6_checksum(skb, hooknum, hdrlen, IPPROTO_ICMPV6))
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return 0;
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inside = (void *)skb->data + hdrlen;
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if (inside->icmp6.icmp6_type == NDISC_REDIRECT) {
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if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
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return 0;
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if (ct->status & IPS_NAT_MASK)
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return 0;
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}
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if (manip == NF_NAT_MANIP_SRC)
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statusbit = IPS_SRC_NAT;
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else
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statusbit = IPS_DST_NAT;
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/* Invert if this is reply direction */
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if (dir == IP_CT_DIR_REPLY)
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statusbit ^= IPS_NAT_MASK;
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if (!(ct->status & statusbit))
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return 1;
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l4proto = __nf_nat_l4proto_find(NFPROTO_IPV6, inside->ip6.nexthdr);
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if (!nf_nat_ipv6_manip_pkt(skb, hdrlen + sizeof(inside->icmp6),
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l4proto, &ct->tuplehash[!dir].tuple, !manip))
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return 0;
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if (skb->ip_summed != CHECKSUM_PARTIAL) {
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struct ipv6hdr *ipv6h = ipv6_hdr(skb);
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inside = (void *)skb->data + hdrlen;
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inside->icmp6.icmp6_cksum = 0;
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inside->icmp6.icmp6_cksum =
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csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
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skb->len - hdrlen, IPPROTO_ICMPV6,
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skb_checksum(skb, hdrlen,
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skb->len - hdrlen, 0));
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}
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nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
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l4proto = __nf_nat_l4proto_find(NFPROTO_IPV6, IPPROTO_ICMPV6);
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if (!nf_nat_ipv6_manip_pkt(skb, 0, l4proto, &target, manip))
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return 0;
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return 1;
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}
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EXPORT_SYMBOL_GPL(nf_nat_icmpv6_reply_translation);
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unsigned int
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nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
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const struct nf_hook_state *state,
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unsigned int (*do_chain)(void *priv,
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struct sk_buff *skb,
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const struct nf_hook_state *state,
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struct nf_conn *ct))
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{
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struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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struct nf_conn_nat *nat;
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enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
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__be16 frag_off;
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int hdrlen;
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u8 nexthdr;
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ct = nf_ct_get(skb, &ctinfo);
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/* Can't track? It's not due to stress, or conntrack would
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* have dropped it. Hence it's the user's responsibilty to
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* packet filter it out, or implement conntrack/NAT for that
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* protocol. 8) --RR
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*/
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if (!ct)
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return NF_ACCEPT;
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nat = nfct_nat(ct);
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switch (ctinfo) {
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case IP_CT_RELATED:
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case IP_CT_RELATED_REPLY:
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nexthdr = ipv6_hdr(skb)->nexthdr;
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hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
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&nexthdr, &frag_off);
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if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
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if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
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state->hook,
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hdrlen))
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return NF_DROP;
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else
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return NF_ACCEPT;
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}
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/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
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case IP_CT_NEW:
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/* Seen it before? This can happen for loopback, retrans,
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* or local packets.
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*/
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if (!nf_nat_initialized(ct, maniptype)) {
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unsigned int ret;
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ret = do_chain(priv, skb, state, ct);
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if (ret != NF_ACCEPT)
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return ret;
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if (nf_nat_initialized(ct, HOOK2MANIP(state->hook)))
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break;
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ret = nf_nat_alloc_null_binding(ct, state->hook);
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if (ret != NF_ACCEPT)
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return ret;
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} else {
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pr_debug("Already setup manip %s for ct %p\n",
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maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
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ct);
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if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
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goto oif_changed;
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}
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break;
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default:
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/* ESTABLISHED */
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WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
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ctinfo != IP_CT_ESTABLISHED_REPLY);
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if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
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goto oif_changed;
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}
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return nf_nat_packet(ct, ctinfo, state->hook, skb);
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oif_changed:
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nf_ct_kill_acct(ct, ctinfo, skb);
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return NF_DROP;
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}
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EXPORT_SYMBOL_GPL(nf_nat_ipv6_fn);
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unsigned int
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nf_nat_ipv6_in(void *priv, struct sk_buff *skb,
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const struct nf_hook_state *state,
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unsigned int (*do_chain)(void *priv,
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struct sk_buff *skb,
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const struct nf_hook_state *state,
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struct nf_conn *ct))
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{
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unsigned int ret;
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struct in6_addr daddr = ipv6_hdr(skb)->daddr;
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ret = nf_nat_ipv6_fn(priv, skb, state, do_chain);
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if (ret != NF_DROP && ret != NF_STOLEN &&
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ipv6_addr_cmp(&daddr, &ipv6_hdr(skb)->daddr))
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skb_dst_drop(skb);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_nat_ipv6_in);
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unsigned int
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nf_nat_ipv6_out(void *priv, struct sk_buff *skb,
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const struct nf_hook_state *state,
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unsigned int (*do_chain)(void *priv,
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struct sk_buff *skb,
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const struct nf_hook_state *state,
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struct nf_conn *ct))
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{
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#ifdef CONFIG_XFRM
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const struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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int err;
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#endif
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unsigned int ret;
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/* root is playing with raw sockets. */
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if (skb->len < sizeof(struct ipv6hdr))
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return NF_ACCEPT;
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ret = nf_nat_ipv6_fn(priv, skb, state, do_chain);
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#ifdef CONFIG_XFRM
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if (ret != NF_DROP && ret != NF_STOLEN &&
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!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
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(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
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&ct->tuplehash[!dir].tuple.dst.u3) ||
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(ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
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ct->tuplehash[dir].tuple.src.u.all !=
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ct->tuplehash[!dir].tuple.dst.u.all)) {
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err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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}
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#endif
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_nat_ipv6_out);
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unsigned int
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nf_nat_ipv6_local_fn(void *priv, struct sk_buff *skb,
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const struct nf_hook_state *state,
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unsigned int (*do_chain)(void *priv,
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struct sk_buff *skb,
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const struct nf_hook_state *state,
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struct nf_conn *ct))
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{
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const struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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unsigned int ret;
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int err;
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/* root is playing with raw sockets. */
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if (skb->len < sizeof(struct ipv6hdr))
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return NF_ACCEPT;
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ret = nf_nat_ipv6_fn(priv, skb, state, do_chain);
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if (ret != NF_DROP && ret != NF_STOLEN &&
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(ct = nf_ct_get(skb, &ctinfo)) != NULL) {
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enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
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if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
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&ct->tuplehash[!dir].tuple.src.u3)) {
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err = ip6_route_me_harder(state->net, skb);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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#ifdef CONFIG_XFRM
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else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
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ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
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ct->tuplehash[dir].tuple.dst.u.all !=
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ct->tuplehash[!dir].tuple.src.u.all) {
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err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
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if (err < 0)
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ret = NF_DROP_ERR(err);
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}
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#endif
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_nat_ipv6_local_fn);
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static int __init nf_nat_l3proto_ipv6_init(void)
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{
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int err;
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err = nf_nat_l4proto_register(NFPROTO_IPV6, &nf_nat_l4proto_icmpv6);
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if (err < 0)
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goto err1;
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err = nf_nat_l3proto_register(&nf_nat_l3proto_ipv6);
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if (err < 0)
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goto err2;
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return err;
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err2:
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nf_nat_l4proto_unregister(NFPROTO_IPV6, &nf_nat_l4proto_icmpv6);
|
|
err1:
|
|
return err;
|
|
}
|
|
|
|
static void __exit nf_nat_l3proto_ipv6_exit(void)
|
|
{
|
|
nf_nat_l3proto_unregister(&nf_nat_l3proto_ipv6);
|
|
nf_nat_l4proto_unregister(NFPROTO_IPV6, &nf_nat_l4proto_icmpv6);
|
|
}
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_ALIAS("nf-nat-" __stringify(AF_INET6));
|
|
|
|
module_init(nf_nat_l3proto_ipv6_init);
|
|
module_exit(nf_nat_l3proto_ipv6_exit);
|