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- /*
- * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
- *
- * 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.
- *
- * Development of IPv6 NAT funded by Astaro.
- */
- #include <linux/types.h>
- #include <linux/module.h>
- #include <linux/skbuff.h>
- #include <linux/ipv6.h>
- #include <linux/netfilter.h>
- #include <linux/netfilter_ipv6.h>
- #include <net/secure_seq.h>
- #include <net/checksum.h>
- #include <net/ip6_checksum.h>
- #include <net/ip6_route.h>
- #include <net/ipv6.h>
- #include <net/netfilter/nf_conntrack_core.h>
- #include <net/netfilter/nf_conntrack.h>
- #include <net/netfilter/nf_nat_core.h>
- #include <net/netfilter/nf_nat_l3proto.h>
- #include <net/netfilter/nf_nat_l4proto.h>
- static const struct nf_nat_l3proto nf_nat_l3proto_ipv6;
- #ifdef CONFIG_XFRM
- static void nf_nat_ipv6_decode_session(struct sk_buff *skb,
- const struct nf_conn *ct,
- enum ip_conntrack_dir dir,
- unsigned long statusbit,
- struct flowi *fl)
- {
- const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
- struct flowi6 *fl6 = &fl->u.ip6;
- if (ct->status & statusbit) {
- fl6->daddr = t->dst.u3.in6;
- if (t->dst.protonum == IPPROTO_TCP ||
- t->dst.protonum == IPPROTO_UDP ||
- t->dst.protonum == IPPROTO_UDPLITE ||
- t->dst.protonum == IPPROTO_DCCP ||
- t->dst.protonum == IPPROTO_SCTP)
- fl6->fl6_dport = t->dst.u.all;
- }
- statusbit ^= IPS_NAT_MASK;
- if (ct->status & statusbit) {
- fl6->saddr = t->src.u3.in6;
- if (t->dst.protonum == IPPROTO_TCP ||
- t->dst.protonum == IPPROTO_UDP ||
- t->dst.protonum == IPPROTO_UDPLITE ||
- t->dst.protonum == IPPROTO_DCCP ||
- t->dst.protonum == IPPROTO_SCTP)
- fl6->fl6_sport = t->src.u.all;
- }
- }
- #endif
- static bool nf_nat_ipv6_in_range(const struct nf_conntrack_tuple *t,
- const struct nf_nat_range *range)
- {
- return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
- ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
- }
- static u32 nf_nat_ipv6_secure_port(const struct nf_conntrack_tuple *t,
- __be16 dport)
- {
- return secure_ipv6_port_ephemeral(t->src.u3.ip6, t->dst.u3.ip6, dport);
- }
- static bool nf_nat_ipv6_manip_pkt(struct sk_buff *skb,
- unsigned int iphdroff,
- const struct nf_nat_l4proto *l4proto,
- const struct nf_conntrack_tuple *target,
- enum nf_nat_manip_type maniptype)
- {
- struct ipv6hdr *ipv6h;
- __be16 frag_off;
- int hdroff;
- u8 nexthdr;
- if (!skb_make_writable(skb, iphdroff + sizeof(*ipv6h)))
- return false;
- ipv6h = (void *)skb->data + iphdroff;
- nexthdr = ipv6h->nexthdr;
- hdroff = ipv6_skip_exthdr(skb, iphdroff + sizeof(*ipv6h),
- &nexthdr, &frag_off);
- if (hdroff < 0)
- goto manip_addr;
- if ((frag_off & htons(~0x7)) == 0 &&
- !l4proto->manip_pkt(skb, &nf_nat_l3proto_ipv6, iphdroff, hdroff,
- target, maniptype))
- return false;
- /* must reload, offset might have changed */
- ipv6h = (void *)skb->data + iphdroff;
- manip_addr:
- if (maniptype == NF_NAT_MANIP_SRC)
- ipv6h->saddr = target->src.u3.in6;
- else
- ipv6h->daddr = target->dst.u3.in6;
- return true;
- }
- static void nf_nat_ipv6_csum_update(struct sk_buff *skb,
- unsigned int iphdroff, __sum16 *check,
- const struct nf_conntrack_tuple *t,
- enum nf_nat_manip_type maniptype)
- {
- const struct ipv6hdr *ipv6h = (struct ipv6hdr *)(skb->data + iphdroff);
- const struct in6_addr *oldip, *newip;
- if (maniptype == NF_NAT_MANIP_SRC) {
- oldip = &ipv6h->saddr;
- newip = &t->src.u3.in6;
- } else {
- oldip = &ipv6h->daddr;
- newip = &t->dst.u3.in6;
- }
- inet_proto_csum_replace16(check, skb, oldip->s6_addr32,
- newip->s6_addr32, true);
- }
- static void nf_nat_ipv6_csum_recalc(struct sk_buff *skb,
- u8 proto, void *data, __sum16 *check,
- int datalen, int oldlen)
- {
- const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
- struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
- if (skb->ip_summed != CHECKSUM_PARTIAL) {
- if (!(rt->rt6i_flags & RTF_LOCAL) &&
- (!skb->dev || skb->dev->features & NETIF_F_V6_CSUM)) {
- skb->ip_summed = CHECKSUM_PARTIAL;
- skb->csum_start = skb_headroom(skb) +
- skb_network_offset(skb) +
- (data - (void *)skb->data);
- skb->csum_offset = (void *)check - data;
- *check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
- datalen, proto, 0);
- } else {
- *check = 0;
- *check = csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
- datalen, proto,
- csum_partial(data, datalen,
- 0));
- if (proto == IPPROTO_UDP && !*check)
- *check = CSUM_MANGLED_0;
- }
- } else
- inet_proto_csum_replace2(check, skb,
- htons(oldlen), htons(datalen), true);
- }
- #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
- static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
- struct nf_nat_range *range)
- {
- if (tb[CTA_NAT_V6_MINIP]) {
- nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
- sizeof(struct in6_addr));
- range->flags |= NF_NAT_RANGE_MAP_IPS;
- }
- if (tb[CTA_NAT_V6_MAXIP])
- nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
- sizeof(struct in6_addr));
- else
- range->max_addr = range->min_addr;
- return 0;
- }
- #endif
- static const struct nf_nat_l3proto nf_nat_l3proto_ipv6 = {
- .l3proto = NFPROTO_IPV6,
- .secure_port = nf_nat_ipv6_secure_port,
- .in_range = nf_nat_ipv6_in_range,
- .manip_pkt = nf_nat_ipv6_manip_pkt,
- .csum_update = nf_nat_ipv6_csum_update,
- .csum_recalc = nf_nat_ipv6_csum_recalc,
- #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
- .nlattr_to_range = nf_nat_ipv6_nlattr_to_range,
- #endif
- #ifdef CONFIG_XFRM
- .decode_session = nf_nat_ipv6_decode_session,
- #endif
- };
- int nf_nat_icmpv6_reply_translation(struct sk_buff *skb,
- struct nf_conn *ct,
- enum ip_conntrack_info ctinfo,
- unsigned int hooknum,
- unsigned int hdrlen)
- {
- struct {
- struct icmp6hdr icmp6;
- struct ipv6hdr ip6;
- } *inside;
- enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
- enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
- const struct nf_nat_l4proto *l4proto;
- struct nf_conntrack_tuple target;
- unsigned long statusbit;
- NF_CT_ASSERT(ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY);
- if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
- return 0;
- if (nf_ip6_checksum(skb, hooknum, hdrlen, IPPROTO_ICMPV6))
- return 0;
- inside = (void *)skb->data + hdrlen;
- if (inside->icmp6.icmp6_type == NDISC_REDIRECT) {
- if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
- return 0;
- if (ct->status & IPS_NAT_MASK)
- return 0;
- }
- if (manip == NF_NAT_MANIP_SRC)
- statusbit = IPS_SRC_NAT;
- else
- statusbit = IPS_DST_NAT;
- /* Invert if this is reply direction */
- if (dir == IP_CT_DIR_REPLY)
- statusbit ^= IPS_NAT_MASK;
- if (!(ct->status & statusbit))
- return 1;
- l4proto = __nf_nat_l4proto_find(NFPROTO_IPV6, inside->ip6.nexthdr);
- if (!nf_nat_ipv6_manip_pkt(skb, hdrlen + sizeof(inside->icmp6),
- l4proto, &ct->tuplehash[!dir].tuple, !manip))
- return 0;
- if (skb->ip_summed != CHECKSUM_PARTIAL) {
- struct ipv6hdr *ipv6h = ipv6_hdr(skb);
- inside = (void *)skb->data + hdrlen;
- inside->icmp6.icmp6_cksum = 0;
- inside->icmp6.icmp6_cksum =
- csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
- skb->len - hdrlen, IPPROTO_ICMPV6,
- csum_partial(&inside->icmp6,
- skb->len - hdrlen, 0));
- }
- nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
- l4proto = __nf_nat_l4proto_find(NFPROTO_IPV6, IPPROTO_ICMPV6);
- if (!nf_nat_ipv6_manip_pkt(skb, 0, l4proto, &target, manip))
- return 0;
- return 1;
- }
- EXPORT_SYMBOL_GPL(nf_nat_icmpv6_reply_translation);
- unsigned int
- nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
- const struct nf_hook_state *state,
- unsigned int (*do_chain)(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state,
- struct nf_conn *ct))
- {
- struct nf_conn *ct;
- enum ip_conntrack_info ctinfo;
- struct nf_conn_nat *nat;
- enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
- __be16 frag_off;
- int hdrlen;
- u8 nexthdr;
- ct = nf_ct_get(skb, &ctinfo);
- /* Can't track? It's not due to stress, or conntrack would
- * have dropped it. Hence it's the user's responsibilty to
- * packet filter it out, or implement conntrack/NAT for that
- * protocol. 8) --RR
- */
- if (!ct)
- return NF_ACCEPT;
- /* Don't try to NAT if this packet is not conntracked */
- if (nf_ct_is_untracked(ct))
- return NF_ACCEPT;
- nat = nf_ct_nat_ext_add(ct);
- if (nat == NULL)
- return NF_ACCEPT;
- switch (ctinfo) {
- case IP_CT_RELATED:
- case IP_CT_RELATED_REPLY:
- nexthdr = ipv6_hdr(skb)->nexthdr;
- hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
- &nexthdr, &frag_off);
- if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
- if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
- state->hook,
- hdrlen))
- return NF_DROP;
- else
- return NF_ACCEPT;
- }
- /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
- case IP_CT_NEW:
- /* Seen it before? This can happen for loopback, retrans,
- * or local packets.
- */
- if (!nf_nat_initialized(ct, maniptype)) {
- unsigned int ret;
- ret = do_chain(priv, skb, state, ct);
- if (ret != NF_ACCEPT)
- return ret;
- if (nf_nat_initialized(ct, HOOK2MANIP(state->hook)))
- break;
- ret = nf_nat_alloc_null_binding(ct, state->hook);
- if (ret != NF_ACCEPT)
- return ret;
- } else {
- pr_debug("Already setup manip %s for ct %p\n",
- maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
- ct);
- if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
- goto oif_changed;
- }
- break;
- default:
- /* ESTABLISHED */
- NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
- ctinfo == IP_CT_ESTABLISHED_REPLY);
- if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
- goto oif_changed;
- }
- return nf_nat_packet(ct, ctinfo, state->hook, skb);
- oif_changed:
- nf_ct_kill_acct(ct, ctinfo, skb);
- return NF_DROP;
- }
- EXPORT_SYMBOL_GPL(nf_nat_ipv6_fn);
- unsigned int
- nf_nat_ipv6_in(void *priv, struct sk_buff *skb,
- const struct nf_hook_state *state,
- unsigned int (*do_chain)(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state,
- struct nf_conn *ct))
- {
- unsigned int ret;
- struct in6_addr daddr = ipv6_hdr(skb)->daddr;
- ret = nf_nat_ipv6_fn(priv, skb, state, do_chain);
- if (ret != NF_DROP && ret != NF_STOLEN &&
- ipv6_addr_cmp(&daddr, &ipv6_hdr(skb)->daddr))
- skb_dst_drop(skb);
- return ret;
- }
- EXPORT_SYMBOL_GPL(nf_nat_ipv6_in);
- unsigned int
- nf_nat_ipv6_out(void *priv, struct sk_buff *skb,
- const struct nf_hook_state *state,
- unsigned int (*do_chain)(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state,
- struct nf_conn *ct))
- {
- #ifdef CONFIG_XFRM
- const struct nf_conn *ct;
- enum ip_conntrack_info ctinfo;
- int err;
- #endif
- unsigned int ret;
- /* root is playing with raw sockets. */
- if (skb->len < sizeof(struct ipv6hdr))
- return NF_ACCEPT;
- ret = nf_nat_ipv6_fn(priv, skb, state, do_chain);
- #ifdef CONFIG_XFRM
- if (ret != NF_DROP && ret != NF_STOLEN &&
- !(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
- (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
- enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
- if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
- &ct->tuplehash[!dir].tuple.dst.u3) ||
- (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
- ct->tuplehash[dir].tuple.src.u.all !=
- ct->tuplehash[!dir].tuple.dst.u.all)) {
- err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
- if (err < 0)
- ret = NF_DROP_ERR(err);
- }
- }
- #endif
- return ret;
- }
- EXPORT_SYMBOL_GPL(nf_nat_ipv6_out);
- unsigned int
- nf_nat_ipv6_local_fn(void *priv, struct sk_buff *skb,
- const struct nf_hook_state *state,
- unsigned int (*do_chain)(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state,
- struct nf_conn *ct))
- {
- const struct nf_conn *ct;
- enum ip_conntrack_info ctinfo;
- unsigned int ret;
- int err;
- /* root is playing with raw sockets. */
- if (skb->len < sizeof(struct ipv6hdr))
- return NF_ACCEPT;
- ret = nf_nat_ipv6_fn(priv, skb, state, do_chain);
- if (ret != NF_DROP && ret != NF_STOLEN &&
- (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
- enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
- if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
- &ct->tuplehash[!dir].tuple.src.u3)) {
- err = ip6_route_me_harder(state->net, skb);
- if (err < 0)
- ret = NF_DROP_ERR(err);
- }
- #ifdef CONFIG_XFRM
- else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
- ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
- ct->tuplehash[dir].tuple.dst.u.all !=
- ct->tuplehash[!dir].tuple.src.u.all) {
- err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
- if (err < 0)
- ret = NF_DROP_ERR(err);
- }
- #endif
- }
- return ret;
- }
- EXPORT_SYMBOL_GPL(nf_nat_ipv6_local_fn);
- static int __init nf_nat_l3proto_ipv6_init(void)
- {
- int err;
- err = nf_nat_l4proto_register(NFPROTO_IPV6, &nf_nat_l4proto_icmpv6);
- if (err < 0)
- goto err1;
- err = nf_nat_l3proto_register(&nf_nat_l3proto_ipv6);
- if (err < 0)
- goto err2;
- return err;
- err2:
- 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);
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