| /* (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. |
| */ |
| |
| /* Everything about the rules for NAT. */ |
| #include <linux/types.h> |
| #include <linux/ip.h> |
| #include <linux/netfilter.h> |
| #include <linux/netfilter_ipv4.h> |
| #include <linux/module.h> |
| #include <linux/kmod.h> |
| #include <linux/skbuff.h> |
| #include <linux/proc_fs.h> |
| #include <net/checksum.h> |
| #include <net/route.h> |
| #include <linux/bitops.h> |
| |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <net/netfilter/nf_nat.h> |
| #include <net/netfilter/nf_nat_core.h> |
| #include <net/netfilter/nf_nat_rule.h> |
| |
| #define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ |
| (1 << NF_INET_POST_ROUTING) | \ |
| (1 << NF_INET_LOCAL_OUT)) |
| |
| static struct |
| { |
| struct ipt_replace repl; |
| struct ipt_standard entries[3]; |
| struct ipt_error term; |
| } nat_initial_table __initdata = { |
| .repl = { |
| .name = "nat", |
| .valid_hooks = NAT_VALID_HOOKS, |
| .num_entries = 4, |
| .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), |
| .hook_entry = { |
| [NF_INET_PRE_ROUTING] = 0, |
| [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard), |
| [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 |
| }, |
| .underflow = { |
| [NF_INET_PRE_ROUTING] = 0, |
| [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard), |
| [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 |
| }, |
| }, |
| .entries = { |
| IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */ |
| IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */ |
| IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */ |
| }, |
| .term = IPT_ERROR_INIT, /* ERROR */ |
| }; |
| |
| static struct xt_table nat_table = { |
| .name = "nat", |
| .valid_hooks = NAT_VALID_HOOKS, |
| .lock = RW_LOCK_UNLOCKED, |
| .me = THIS_MODULE, |
| .af = AF_INET, |
| }; |
| |
| /* Source NAT */ |
| static unsigned int ipt_snat_target(struct sk_buff *skb, |
| const struct net_device *in, |
| const struct net_device *out, |
| unsigned int hooknum, |
| const struct xt_target *target, |
| const void *targinfo) |
| { |
| struct nf_conn *ct; |
| enum ip_conntrack_info ctinfo; |
| const struct nf_nat_multi_range_compat *mr = targinfo; |
| |
| NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING); |
| |
| ct = nf_ct_get(skb, &ctinfo); |
| |
| /* Connection must be valid and new. */ |
| NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || |
| ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); |
| NF_CT_ASSERT(out); |
| |
| return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC); |
| } |
| |
| /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */ |
| static void warn_if_extra_mangle(__be32 dstip, __be32 srcip) |
| { |
| static int warned = 0; |
| struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } }; |
| struct rtable *rt; |
| |
| if (ip_route_output_key(&rt, &fl) != 0) |
| return; |
| |
| if (rt->rt_src != srcip && !warned) { |
| printk("NAT: no longer support implicit source local NAT\n"); |
| printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n", |
| NIPQUAD(srcip), NIPQUAD(dstip)); |
| warned = 1; |
| } |
| ip_rt_put(rt); |
| } |
| |
| static unsigned int ipt_dnat_target(struct sk_buff *skb, |
| const struct net_device *in, |
| const struct net_device *out, |
| unsigned int hooknum, |
| const struct xt_target *target, |
| const void *targinfo) |
| { |
| struct nf_conn *ct; |
| enum ip_conntrack_info ctinfo; |
| const struct nf_nat_multi_range_compat *mr = targinfo; |
| |
| NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING || |
| hooknum == NF_INET_LOCAL_OUT); |
| |
| ct = nf_ct_get(skb, &ctinfo); |
| |
| /* Connection must be valid and new. */ |
| NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); |
| |
| if (hooknum == NF_INET_LOCAL_OUT && |
| mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) |
| warn_if_extra_mangle(ip_hdr(skb)->daddr, |
| mr->range[0].min_ip); |
| |
| return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST); |
| } |
| |
| static bool ipt_snat_checkentry(const char *tablename, |
| const void *entry, |
| const struct xt_target *target, |
| void *targinfo, |
| unsigned int hook_mask) |
| { |
| struct nf_nat_multi_range_compat *mr = targinfo; |
| |
| /* Must be a valid range */ |
| if (mr->rangesize != 1) { |
| printk("SNAT: multiple ranges no longer supported\n"); |
| return false; |
| } |
| return true; |
| } |
| |
| static bool ipt_dnat_checkentry(const char *tablename, |
| const void *entry, |
| const struct xt_target *target, |
| void *targinfo, |
| unsigned int hook_mask) |
| { |
| struct nf_nat_multi_range_compat *mr = targinfo; |
| |
| /* Must be a valid range */ |
| if (mr->rangesize != 1) { |
| printk("DNAT: multiple ranges no longer supported\n"); |
| return false; |
| } |
| return true; |
| } |
| |
| 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). |
| Use reply in case it's already been mangled (eg local packet). |
| */ |
| __be32 ip |
| = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC |
| ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip |
| : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); |
| struct nf_nat_range range |
| = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } }; |
| |
| pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n", |
| ct, NIPQUAD(ip)); |
| return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum)); |
| } |
| |
| unsigned int |
| alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum) |
| { |
| __be32 ip |
| = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC |
| ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip |
| : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); |
| __be16 all |
| = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC |
| ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all |
| : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all); |
| struct nf_nat_range range |
| = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } }; |
| |
| pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n", |
| ct, NIPQUAD(ip)); |
| return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum)); |
| } |
| |
| 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) |
| { |
| int ret; |
| |
| ret = ipt_do_table(skb, hooknum, in, out, &nat_table); |
| |
| if (ret == NF_ACCEPT) { |
| if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum))) |
| /* NUL mapping */ |
| ret = alloc_null_binding(ct, hooknum); |
| } |
| return ret; |
| } |
| |
| static struct xt_target ipt_snat_reg __read_mostly = { |
| .name = "SNAT", |
| .target = ipt_snat_target, |
| .targetsize = sizeof(struct nf_nat_multi_range_compat), |
| .table = "nat", |
| .hooks = 1 << NF_INET_POST_ROUTING, |
| .checkentry = ipt_snat_checkentry, |
| .family = AF_INET, |
| }; |
| |
| static struct xt_target ipt_dnat_reg __read_mostly = { |
| .name = "DNAT", |
| .target = ipt_dnat_target, |
| .targetsize = sizeof(struct nf_nat_multi_range_compat), |
| .table = "nat", |
| .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT), |
| .checkentry = ipt_dnat_checkentry, |
| .family = AF_INET, |
| }; |
| |
| int __init nf_nat_rule_init(void) |
| { |
| int ret; |
| |
| ret = ipt_register_table(&nat_table, &nat_initial_table.repl); |
| if (ret != 0) |
| return ret; |
| ret = xt_register_target(&ipt_snat_reg); |
| if (ret != 0) |
| goto unregister_table; |
| |
| ret = xt_register_target(&ipt_dnat_reg); |
| if (ret != 0) |
| goto unregister_snat; |
| |
| return ret; |
| |
| unregister_snat: |
| xt_unregister_target(&ipt_snat_reg); |
| unregister_table: |
| ipt_unregister_table(&nat_table); |
| |
| return ret; |
| } |
| |
| void nf_nat_rule_cleanup(void) |
| { |
| xt_unregister_target(&ipt_dnat_reg); |
| xt_unregister_target(&ipt_snat_reg); |
| ipt_unregister_table(&nat_table); |
| } |