![Patrick McHardy](/assets/img/avatar_default.png)
Convert the IPv4 NAT implementation to a protocol independent core and address family specific modules. Signed-off-by: Patrick McHardy <kaber@trash.net>
282 lines
7.7 KiB
C
282 lines
7.7 KiB
C
/*
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* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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* (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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#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/ip.h>
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#include <linux/icmp.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <net/secure_seq.h>
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#include <net/checksum.h>
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#include <net/route.h>
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#include <net/ip.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_ipv4;
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#ifdef CONFIG_XFRM
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static void nf_nat_ipv4_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 flowi4 *fl4 = &fl->u.ip4;
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if (ct->status & statusbit) {
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fl4->daddr = t->dst.u3.ip;
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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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fl4->fl4_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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fl4->saddr = t->src.u3.ip;
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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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fl4->fl4_sport = t->src.u.all;
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}
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}
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#endif /* CONFIG_XFRM */
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static bool nf_nat_ipv4_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 ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) &&
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ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip);
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}
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static u32 nf_nat_ipv4_secure_port(const struct nf_conntrack_tuple *t,
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__be16 dport)
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{
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return secure_ipv4_port_ephemeral(t->src.u3.ip, t->dst.u3.ip, dport);
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}
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static bool nf_nat_ipv4_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 iphdr *iph;
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unsigned int hdroff;
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if (!skb_make_writable(skb, iphdroff + sizeof(*iph)))
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return false;
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iph = (void *)skb->data + iphdroff;
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hdroff = iphdroff + iph->ihl * 4;
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if (!l4proto->manip_pkt(skb, &nf_nat_l3proto_ipv4, iphdroff, hdroff,
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target, maniptype))
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return false;
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iph = (void *)skb->data + iphdroff;
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if (maniptype == NF_NAT_MANIP_SRC) {
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csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
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iph->saddr = target->src.u3.ip;
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} else {
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csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
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iph->daddr = target->dst.u3.ip;
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}
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return true;
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}
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static void nf_nat_ipv4_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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struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
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__be32 oldip, newip;
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if (maniptype == NF_NAT_MANIP_SRC) {
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oldip = iph->saddr;
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newip = t->src.u3.ip;
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} else {
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oldip = iph->daddr;
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newip = t->dst.u3.ip;
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}
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inet_proto_csum_replace4(check, skb, oldip, newip, 1);
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}
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static void nf_nat_ipv4_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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const struct iphdr *iph = ip_hdr(skb);
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struct rtable *rt = skb_rtable(skb);
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if (skb->ip_summed != CHECKSUM_PARTIAL) {
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if (!(rt->rt_flags & RTCF_LOCAL) &&
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(!skb->dev || skb->dev->features & NETIF_F_V4_CSUM)) {
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skb->ip_summed = CHECKSUM_PARTIAL;
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skb->csum_start = skb_headroom(skb) +
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skb_network_offset(skb) +
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ip_hdrlen(skb);
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skb->csum_offset = (void *)check - data;
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*check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
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datalen, proto, 0);
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} else {
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*check = 0;
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*check = csum_tcpudp_magic(iph->saddr, iph->daddr,
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datalen, proto,
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csum_partial(data, datalen,
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0));
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if (proto == IPPROTO_UDP && !*check)
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*check = CSUM_MANGLED_0;
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}
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} else
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inet_proto_csum_replace2(check, skb,
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htons(oldlen), htons(datalen), 1);
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}
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static int nf_nat_ipv4_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_V4_MINIP]) {
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range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]);
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range->flags |= NF_NAT_RANGE_MAP_IPS;
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}
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if (tb[CTA_NAT_V4_MAXIP])
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range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]);
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else
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range->max_addr.ip = range->min_addr.ip;
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return 0;
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}
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static const struct nf_nat_l3proto nf_nat_l3proto_ipv4 = {
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.l3proto = NFPROTO_IPV4,
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.in_range = nf_nat_ipv4_in_range,
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.secure_port = nf_nat_ipv4_secure_port,
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.manip_pkt = nf_nat_ipv4_manip_pkt,
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.csum_update = nf_nat_ipv4_csum_update,
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.csum_recalc = nf_nat_ipv4_csum_recalc,
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.nlattr_to_range = nf_nat_ipv4_nlattr_to_range,
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#ifdef CONFIG_XFRM
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.decode_session = nf_nat_ipv4_decode_session,
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#endif
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};
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int nf_nat_icmp_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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{
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struct {
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struct icmphdr icmp;
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struct iphdr ip;
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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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unsigned int hdrlen = ip_hdrlen(skb);
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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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NF_CT_ASSERT(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_ip_checksum(skb, hooknum, hdrlen, 0))
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return 0;
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inside = (void *)skb->data + hdrlen;
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if (inside->icmp.type == ICMP_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_IPV4, inside->ip.protocol);
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if (!nf_nat_ipv4_manip_pkt(skb, hdrlen + sizeof(inside->icmp),
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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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/* Reloading "inside" here since manip_pkt may reallocate */
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inside = (void *)skb->data + hdrlen;
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inside->icmp.checksum = 0;
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inside->icmp.checksum =
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csum_fold(skb_checksum(skb, hdrlen,
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skb->len - hdrlen, 0));
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}
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/* Change outer to look like the reply to an incoming packet */
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nf_ct_invert_tuplepr(&target, &ct->tuplehash[!dir].tuple);
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l4proto = __nf_nat_l4proto_find(NFPROTO_IPV4, 0);
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if (!nf_nat_ipv4_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_icmp_reply_translation);
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static int __init nf_nat_l3proto_ipv4_init(void)
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{
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int err;
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err = nf_nat_l4proto_register(NFPROTO_IPV4, &nf_nat_l4proto_icmp);
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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_ipv4);
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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_IPV4, &nf_nat_l4proto_icmp);
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err1:
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return err;
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}
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static void __exit nf_nat_l3proto_ipv4_exit(void)
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{
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nf_nat_l3proto_unregister(&nf_nat_l3proto_ipv4);
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nf_nat_l4proto_unregister(NFPROTO_IPV4, &nf_nat_l4proto_icmp);
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}
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("nf-nat-" __stringify(AF_INET));
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module_init(nf_nat_l3proto_ipv4_init);
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module_exit(nf_nat_l3proto_ipv4_exit);
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