diff options
Diffstat (limited to 'net/ipv4/netfilter/nf_nat_rule.c')
| -rw-r--r-- | net/ipv4/netfilter/nf_nat_rule.c | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_nat_rule.c b/net/ipv4/netfilter/nf_nat_rule.c new file mode 100644 index 00000000..733c9abc --- /dev/null +++ b/net/ipv4/netfilter/nf_nat_rule.c @@ -0,0 +1,214 @@ +/* (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. */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#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 <linux/slab.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) | \ + (1 << NF_INET_LOCAL_IN)) + +static const struct xt_table nat_table = { + .name = "nat", + .valid_hooks = NAT_VALID_HOOKS, + .me = THIS_MODULE, + .af = NFPROTO_IPV4, +}; + +/* Source NAT */ +static unsigned int +ipt_snat_target(struct sk_buff *skb, const struct xt_action_param *par) +{ + struct nf_conn *ct; + enum ip_conntrack_info ctinfo; + const struct nf_nat_multi_range_compat *mr = par->targinfo; + + NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING || + par->hooknum == NF_INET_LOCAL_IN); + + 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_REPLY)); + NF_CT_ASSERT(par->out != NULL); + + return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC); +} + +static unsigned int +ipt_dnat_target(struct sk_buff *skb, const struct xt_action_param *par) +{ + struct nf_conn *ct; + enum ip_conntrack_info ctinfo; + const struct nf_nat_multi_range_compat *mr = par->targinfo; + + NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING || + par->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)); + + return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST); +} + +static int ipt_snat_checkentry(const struct xt_tgchk_param *par) +{ + const struct nf_nat_multi_range_compat *mr = par->targinfo; + + /* Must be a valid range */ + if (mr->rangesize != 1) { + pr_info("SNAT: multiple ranges no longer supported\n"); + return -EINVAL; + } + return 0; +} + +static int ipt_dnat_checkentry(const struct xt_tgchk_param *par) +{ + const struct nf_nat_multi_range_compat *mr = par->targinfo; + + /* Must be a valid range */ + if (mr->rangesize != 1) { + pr_info("DNAT: multiple ranges no longer supported\n"); + return -EINVAL; + } + return 0; +} + +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) == IP_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)); +} + +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); + 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))) + /* 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) | (1 << NF_INET_LOCAL_IN), + .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, +}; + +static int __net_init nf_nat_rule_net_init(struct net *net) +{ + struct ipt_replace *repl; + + repl = ipt_alloc_initial_table(&nat_table); + if (repl == NULL) + return -ENOMEM; + net->ipv4.nat_table = ipt_register_table(net, &nat_table, repl); + kfree(repl); + if (IS_ERR(net->ipv4.nat_table)) + return PTR_ERR(net->ipv4.nat_table); + return 0; +} + +static void __net_exit nf_nat_rule_net_exit(struct net *net) +{ + ipt_unregister_table(net, net->ipv4.nat_table); +} + +static struct pernet_operations nf_nat_rule_net_ops = { + .init = nf_nat_rule_net_init, + .exit = nf_nat_rule_net_exit, +}; + +int __init nf_nat_rule_init(void) +{ + int ret; + + ret = register_pernet_subsys(&nf_nat_rule_net_ops); + if (ret != 0) + goto out; + 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: + unregister_pernet_subsys(&nf_nat_rule_net_ops); + out: + return ret; +} + +void nf_nat_rule_cleanup(void) +{ + xt_unregister_target(&ipt_dnat_reg); + xt_unregister_target(&ipt_snat_reg); + unregister_pernet_subsys(&nf_nat_rule_net_ops); +} |