| /* (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/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) |
| { |
| 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) { |
| fl->fl4_dst = 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) |
| fl->fl_ip_dport = t->dst.u.tcp.port; |
| } |
| |
| statusbit ^= IPS_NAT_MASK; |
| |
| if (ct->status & statusbit) { |
| fl->fl4_src = 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) |
| fl->fl_ip_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 (ct == &nf_conntrack_untracked) |
| 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+IP_CT_IS_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; |
| |
| if (hooknum == NF_INET_LOCAL_IN) |
| /* LOCAL_IN hook doesn't have a chain! */ |
| ret = alloc_null_binding(ct, hooknum); |
| else |
| 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+IP_CT_IS_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) { |
| printk("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) { |
| printk("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"); |