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-rw-r--r--net/ipv4/netfilter/iptable_nat.c320
1 files changed, 320 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/iptable_nat.c b/net/ipv4/netfilter/iptable_nat.c
new file mode 100644
index 0000000..9e0ffaf
--- /dev/null
+++ b/net/ipv4/netfilter/iptable_nat.c
@@ -0,0 +1,320 @@
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ * (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.
+ */
+
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/ip.h>
+#include <net/ip.h>
+
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_nat_l3proto.h>
+
+static const struct xt_table nf_nat_ipv4_table = {
+ .name = "nat",
+ .valid_hooks = (1 << NF_INET_PRE_ROUTING) |
+ (1 << NF_INET_POST_ROUTING) |
+ (1 << NF_INET_LOCAL_OUT) |
+ (1 << NF_INET_LOCAL_IN),
+ .me = THIS_MODULE,
+ .af = NFPROTO_IPV4,
+};
+
+static unsigned int alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
+{
+ /* Force range to this IP; let proto decide mapping for
+ * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
+ */
+ struct nf_nat_range range;
+
+ range.flags = 0;
+ pr_debug("Allocating NULL binding for %p (%pI4)\n", ct,
+ HOOK2MANIP(hooknum) == NF_NAT_MANIP_SRC ?
+ &ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip :
+ &ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
+
+ return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
+}
+
+static unsigned int nf_nat_rule_find(struct sk_buff *skb, unsigned int hooknum,
+ const struct net_device *in,
+ const struct net_device *out,
+ struct nf_conn *ct)
+{
+ struct net *net = nf_ct_net(ct);
+ unsigned int ret;
+
+ ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table);
+ if (ret == NF_ACCEPT) {
+ if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
+ ret = alloc_null_binding(ct, hooknum);
+ }
+ return ret;
+}
+
+static unsigned int
+nf_nat_ipv4_fn(unsigned int hooknum,
+ struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+ struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn_nat *nat;
+ /* maniptype == SRC for postrouting. */
+ enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum);
+
+ /* We never see fragments: conntrack defrags on pre-routing
+ * and local-out, and nf_nat_out protects post-routing.
+ */
+ NF_CT_ASSERT(!ip_is_fragment(ip_hdr(skb)));
+
+ 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 = nfct_nat(ct);
+ if (!nat) {
+ /* NAT module was loaded late. */
+ if (nf_ct_is_confirmed(ct))
+ return NF_ACCEPT;
+ nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
+ if (nat == NULL) {
+ pr_debug("failed to add NAT extension\n");
+ return NF_ACCEPT;
+ }
+ }
+
+ switch (ctinfo) {
+ case IP_CT_RELATED:
+ case IP_CT_RELATED_REPLY:
+ if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
+ if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
+ hooknum))
+ 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 = nf_nat_rule_find(skb, hooknum, in, out, ct);
+ 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);
+ break;
+
+ default:
+ /* ESTABLISHED */
+ NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED ||
+ ctinfo == IP_CT_ESTABLISHED_REPLY);
+ }
+
+ return nf_nat_packet(ct, ctinfo, hooknum, skb);
+}
+
+static unsigned int
+nf_nat_ipv4_in(unsigned int hooknum,
+ struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+ unsigned int ret;
+ __be32 daddr = ip_hdr(skb)->daddr;
+
+ ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn);
+ if (ret != NF_DROP && ret != NF_STOLEN &&
+ daddr != ip_hdr(skb)->daddr)
+ skb_dst_drop(skb);
+
+ return ret;
+}
+
+static unsigned int
+nf_nat_ipv4_out(unsigned int hooknum,
+ struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+#ifdef CONFIG_XFRM
+ const struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+#endif
+ unsigned int ret;
+
+ /* root is playing with raw sockets. */
+ if (skb->len < sizeof(struct iphdr) ||
+ ip_hdrlen(skb) < sizeof(struct iphdr))
+ return NF_ACCEPT;
+
+ ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn);
+#ifdef CONFIG_XFRM
+ if (ret != NF_DROP && ret != NF_STOLEN &&
+ !(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
+ (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+
+ if ((ct->tuplehash[dir].tuple.src.u3.ip !=
+ ct->tuplehash[!dir].tuple.dst.u3.ip) ||
+ (ct->tuplehash[dir].tuple.src.u.all !=
+ ct->tuplehash[!dir].tuple.dst.u.all))
+ if (nf_xfrm_me_harder(skb, AF_INET) < 0)
+ ret = NF_DROP;
+ }
+#endif
+ return ret;
+}
+
+static unsigned int
+nf_nat_ipv4_local_fn(unsigned int hooknum,
+ struct sk_buff *skb,
+ const struct net_device *in,
+ const struct net_device *out,
+ int (*okfn)(struct sk_buff *))
+{
+ const struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ unsigned int ret;
+
+ /* root is playing with raw sockets. */
+ if (skb->len < sizeof(struct iphdr) ||
+ ip_hdrlen(skb) < sizeof(struct iphdr))
+ return NF_ACCEPT;
+
+ ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn);
+ if (ret != NF_DROP && ret != NF_STOLEN &&
+ (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+
+ if (ct->tuplehash[dir].tuple.dst.u3.ip !=
+ ct->tuplehash[!dir].tuple.src.u3.ip) {
+ if (ip_route_me_harder(skb, RTN_UNSPEC))
+ ret = NF_DROP;
+ }
+#ifdef CONFIG_XFRM
+ else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
+ ct->tuplehash[dir].tuple.dst.u.all !=
+ ct->tuplehash[!dir].tuple.src.u.all)
+ if (nf_xfrm_me_harder(skb, AF_INET) < 0)
+ ret = NF_DROP;
+#endif
+ }
+ return ret;
+}
+
+static struct nf_hook_ops nf_nat_ipv4_ops[] __read_mostly = {
+ /* Before packet filtering, change destination */
+ {
+ .hook = nf_nat_ipv4_in,
+ .owner = THIS_MODULE,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_PRE_ROUTING,
+ .priority = NF_IP_PRI_NAT_DST,
+ },
+ /* After packet filtering, change source */
+ {
+ .hook = nf_nat_ipv4_out,
+ .owner = THIS_MODULE,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_POST_ROUTING,
+ .priority = NF_IP_PRI_NAT_SRC,
+ },
+ /* Before packet filtering, change destination */
+ {
+ .hook = nf_nat_ipv4_local_fn,
+ .owner = THIS_MODULE,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_LOCAL_OUT,
+ .priority = NF_IP_PRI_NAT_DST,
+ },
+ /* After packet filtering, change source */
+ {
+ .hook = nf_nat_ipv4_fn,
+ .owner = THIS_MODULE,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_LOCAL_IN,
+ .priority = NF_IP_PRI_NAT_SRC,
+ },
+};
+
+static int __net_init iptable_nat_net_init(struct net *net)
+{
+ struct ipt_replace *repl;
+
+ repl = ipt_alloc_initial_table(&nf_nat_ipv4_table);
+ if (repl == NULL)
+ return -ENOMEM;
+ net->ipv4.nat_table = ipt_register_table(net, &nf_nat_ipv4_table, repl);
+ kfree(repl);
+ if (IS_ERR(net->ipv4.nat_table))
+ return PTR_ERR(net->ipv4.nat_table);
+ return 0;
+}
+
+static void __net_exit iptable_nat_net_exit(struct net *net)
+{
+ ipt_unregister_table(net, net->ipv4.nat_table);
+}
+
+static struct pernet_operations iptable_nat_net_ops = {
+ .init = iptable_nat_net_init,
+ .exit = iptable_nat_net_exit,
+};
+
+static int __init iptable_nat_init(void)
+{
+ int err;
+
+ err = register_pernet_subsys(&iptable_nat_net_ops);
+ if (err < 0)
+ goto err1;
+
+ err = nf_register_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops));
+ if (err < 0)
+ goto err2;
+ return 0;
+
+err2:
+ unregister_pernet_subsys(&iptable_nat_net_ops);
+err1:
+ return err;
+}
+
+static void __exit iptable_nat_exit(void)
+{
+ nf_unregister_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops));
+ unregister_pernet_subsys(&iptable_nat_net_ops);
+}
+
+module_init(iptable_nat_init);
+module_exit(iptable_nat_exit);
+
+MODULE_LICENSE("GPL");
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