diff options
Diffstat (limited to 'net/ipv4/netfilter/ipt_MASQUERADE.c')
| -rw-r--r-- | net/ipv4/netfilter/ipt_MASQUERADE.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ipt_MASQUERADE.c b/net/ipv4/netfilter/ipt_MASQUERADE.c new file mode 100644 index 00000000..9931152a --- /dev/null +++ b/net/ipv4/netfilter/ipt_MASQUERADE.c @@ -0,0 +1,173 @@ +/* Masquerade. Simple mapping which alters range to a local IP address + (depending on route). */ + +/* (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. + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/types.h> +#include <linux/inetdevice.h> +#include <linux/ip.h> +#include <linux/timer.h> +#include <linux/module.h> +#include <linux/netfilter.h> +#include <net/protocol.h> +#include <net/ip.h> +#include <net/checksum.h> +#include <net/route.h> +#include <net/netfilter/nf_nat_rule.h> +#include <linux/netfilter_ipv4.h> +#include <linux/netfilter/x_tables.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); +MODULE_DESCRIPTION("Xtables: automatic-address SNAT"); + +/* FIXME: Multiple targets. --RR */ +static int masquerade_tg_check(const struct xt_tgchk_param *par) +{ + const struct nf_nat_multi_range_compat *mr = par->targinfo; + + if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) { + pr_debug("bad MAP_IPS.\n"); + return -EINVAL; + } + if (mr->rangesize != 1) { + pr_debug("bad rangesize %u\n", mr->rangesize); + return -EINVAL; + } + return 0; +} + +static unsigned int +masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par) +{ + struct nf_conn *ct; + struct nf_conn_nat *nat; + enum ip_conntrack_info ctinfo; + struct nf_nat_range newrange; + const struct nf_nat_multi_range_compat *mr; + const struct rtable *rt; + __be32 newsrc; + + NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING); + + ct = nf_ct_get(skb, &ctinfo); + nat = nfct_nat(ct); + + NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || + ctinfo == IP_CT_RELATED_REPLY)); + + /* Source address is 0.0.0.0 - locally generated packet that is + * probably not supposed to be masqueraded. + */ + if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0) + return NF_ACCEPT; + + mr = par->targinfo; + rt = skb_rtable(skb); + newsrc = inet_select_addr(par->out, rt->rt_gateway, RT_SCOPE_UNIVERSE); + if (!newsrc) { + pr_info("%s ate my IP address\n", par->out->name); + return NF_DROP; + } + + nat->masq_index = par->out->ifindex; + + /* Transfer from original range. */ + newrange = ((struct nf_nat_range) + { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS, + newsrc, newsrc, + mr->range[0].min, mr->range[0].max }); + + /* Hand modified range to generic setup. */ + return nf_nat_setup_info(ct, &newrange, IP_NAT_MANIP_SRC); +} + +static int +device_cmp(struct nf_conn *i, void *ifindex) +{ + const struct nf_conn_nat *nat = nfct_nat(i); + + if (!nat) + return 0; + + return nat->masq_index == (int)(long)ifindex; +} + +static int masq_device_event(struct notifier_block *this, + unsigned long event, + void *ptr) +{ + const struct net_device *dev = ptr; + struct net *net = dev_net(dev); + + if (event == NETDEV_DOWN) { + /* Device was downed. Search entire table for + conntracks which were associated with that device, + and forget them. */ + NF_CT_ASSERT(dev->ifindex != 0); + + nf_ct_iterate_cleanup(net, device_cmp, + (void *)(long)dev->ifindex); + } + + return NOTIFY_DONE; +} + +static int masq_inet_event(struct notifier_block *this, + unsigned long event, + void *ptr) +{ + struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev; + return masq_device_event(this, event, dev); +} + +static struct notifier_block masq_dev_notifier = { + .notifier_call = masq_device_event, +}; + +static struct notifier_block masq_inet_notifier = { + .notifier_call = masq_inet_event, +}; + +static struct xt_target masquerade_tg_reg __read_mostly = { + .name = "MASQUERADE", + .family = NFPROTO_IPV4, + .target = masquerade_tg, + .targetsize = sizeof(struct nf_nat_multi_range_compat), + .table = "nat", + .hooks = 1 << NF_INET_POST_ROUTING, + .checkentry = masquerade_tg_check, + .me = THIS_MODULE, +}; + +static int __init masquerade_tg_init(void) +{ + int ret; + + ret = xt_register_target(&masquerade_tg_reg); + + if (ret == 0) { + /* Register for device down reports */ + register_netdevice_notifier(&masq_dev_notifier); + /* Register IP address change reports */ + register_inetaddr_notifier(&masq_inet_notifier); + } + + return ret; +} + +static void __exit masquerade_tg_exit(void) +{ + xt_unregister_target(&masquerade_tg_reg); + unregister_netdevice_notifier(&masq_dev_notifier); + unregister_inetaddr_notifier(&masq_inet_notifier); +} + +module_init(masquerade_tg_init); +module_exit(masquerade_tg_exit); |