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-rw-r--r--net/ipv4/netfilter/nf_nat_standalone.c326
1 files changed, 326 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_nat_standalone.c b/net/ipv4/netfilter/nf_nat_standalone.c
new file mode 100644
index 00000000..483b76d0
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_standalone.c
@@ -0,0 +1,326 @@
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * 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/types.h>
+#include <linux/icmp.h>
+#include <linux/gfp.h>
+#include <linux/ip.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/proc_fs.h>
+#include <net/ip.h>
+#include <net/checksum.h>
+#include <linux/spinlock.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_extend.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_nat_protocol.h>
+#include <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+
+#ifdef CONFIG_XFRM
+static void nat_decode_session(struct sk_buff *skb, struct flowi *fl)
+{
+ struct flowi4 *fl4 = &fl->u.ip4;
+ const struct nf_conn *ct;
+ const struct nf_conntrack_tuple *t;
+ enum ip_conntrack_info ctinfo;
+ enum ip_conntrack_dir dir;
+ unsigned long statusbit;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct == NULL)
+ return;
+ dir = CTINFO2DIR(ctinfo);
+ t = &ct->tuplehash[dir].tuple;
+
+ if (dir == IP_CT_DIR_ORIGINAL)
+ statusbit = IPS_DST_NAT;
+ else
+ statusbit = IPS_SRC_NAT;
+
+ if (ct->status & statusbit) {
+ fl4->daddr = t->dst.u3.ip;
+ 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)
+ fl4->fl4_dport = t->dst.u.tcp.port;
+ }
+
+ statusbit ^= IPS_NAT_MASK;
+
+ if (ct->status & statusbit) {
+ fl4->saddr = t->src.u3.ip;
+ 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)
+ fl4->fl4_sport = t->src.u.tcp.port;
+ }
+}
+#endif
+
+static unsigned int
+nf_nat_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_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)));
+
+ 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(ct, ctinfo,
+ hooknum, skb))
+ 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 == IP_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_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_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_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_fn(hooknum, skb, in, out, okfn);
+#ifdef CONFIG_XFRM
+ 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.src.u3.ip !=
+ ct->tuplehash[!dir].tuple.dst.u3.ip) ||
+ (ct->tuplehash[dir].tuple.src.u.all !=
+ ct->tuplehash[!dir].tuple.dst.u.all)
+ )
+ return ip_xfrm_me_harder(skb) == 0 ? ret : NF_DROP;
+ }
+#endif
+ return ret;
+}
+
+static unsigned int
+nf_nat_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_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 (ct->tuplehash[dir].tuple.dst.u.all !=
+ ct->tuplehash[!dir].tuple.src.u.all)
+ if (ip_xfrm_me_harder(skb))
+ ret = NF_DROP;
+#endif
+ }
+ return ret;
+}
+
+/* We must be after connection tracking and before packet filtering. */
+
+static struct nf_hook_ops nf_nat_ops[] __read_mostly = {
+ /* Before packet filtering, change destination */
+ {
+ .hook = nf_nat_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_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_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_fn,
+ .owner = THIS_MODULE,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_LOCAL_IN,
+ .priority = NF_IP_PRI_NAT_SRC,
+ },
+};
+
+static int __init nf_nat_standalone_init(void)
+{
+ int ret = 0;
+
+ need_ipv4_conntrack();
+
+#ifdef CONFIG_XFRM
+ BUG_ON(ip_nat_decode_session != NULL);
+ rcu_assign_pointer(ip_nat_decode_session, nat_decode_session);
+#endif
+ ret = nf_nat_rule_init();
+ if (ret < 0) {
+ pr_err("nf_nat_init: can't setup rules.\n");
+ goto cleanup_decode_session;
+ }
+ ret = nf_register_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops));
+ if (ret < 0) {
+ pr_err("nf_nat_init: can't register hooks.\n");
+ goto cleanup_rule_init;
+ }
+ return ret;
+
+ cleanup_rule_init:
+ nf_nat_rule_cleanup();
+ cleanup_decode_session:
+#ifdef CONFIG_XFRM
+ rcu_assign_pointer(ip_nat_decode_session, NULL);
+ synchronize_net();
+#endif
+ return ret;
+}
+
+static void __exit nf_nat_standalone_fini(void)
+{
+ nf_unregister_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops));
+ nf_nat_rule_cleanup();
+#ifdef CONFIG_XFRM
+ rcu_assign_pointer(ip_nat_decode_session, NULL);
+ synchronize_net();
+#endif
+ /* Conntrack caches are unregistered in nf_conntrack_cleanup */
+}
+
+module_init(nf_nat_standalone_init);
+module_exit(nf_nat_standalone_fini);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_nat");
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-01 06:47:43 +0000