diff options
Diffstat (limited to 'net/ipv4/netfilter/nf_nat_masquerade_ipv4.c')
| -rw-r--r-- | net/ipv4/netfilter/nf_nat_masquerade_ipv4.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/nf_nat_masquerade_ipv4.c b/net/ipv4/netfilter/nf_nat_masquerade_ipv4.c new file mode 100644 index 000000000000..c6eb42100e9a --- /dev/null +++ b/net/ipv4/netfilter/nf_nat_masquerade_ipv4.c @@ -0,0 +1,153 @@ +/* (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/module.h> +#include <linux/atomic.h> +#include <linux/inetdevice.h> +#include <linux/ip.h> +#include <linux/timer.h> +#include <linux/netfilter.h> +#include <net/protocol.h> +#include <net/ip.h> +#include <net/checksum.h> +#include <net/route.h> +#include <linux/netfilter_ipv4.h> +#include <linux/netfilter/x_tables.h> +#include <net/netfilter/nf_nat.h> +#include <net/netfilter/ipv4/nf_nat_masquerade.h> + +unsigned int +nf_nat_masquerade_ipv4(struct sk_buff *skb, unsigned int hooknum, + const struct nf_nat_range *range, + const struct net_device *out) +{ + struct nf_conn *ct; + struct nf_conn_nat *nat; + enum ip_conntrack_info ctinfo; + struct nf_nat_range newrange; + const struct rtable *rt; + __be32 newsrc, nh; + + NF_CT_ASSERT(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; + + rt = skb_rtable(skb); + nh = rt_nexthop(rt, ip_hdr(skb)->daddr); + newsrc = inet_select_addr(out, nh, RT_SCOPE_UNIVERSE); + if (!newsrc) { + pr_info("%s ate my IP address\n", out->name); + return NF_DROP; + } + + nat->masq_index = out->ifindex; + + /* Transfer from original range. */ + memset(&newrange.min_addr, 0, sizeof(newrange.min_addr)); + memset(&newrange.max_addr, 0, sizeof(newrange.max_addr)); + newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS; + newrange.min_addr.ip = newsrc; + newrange.max_addr.ip = newsrc; + newrange.min_proto = range->min_proto; + newrange.max_proto = range->max_proto; + + /* Hand modified range to generic setup. */ + return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC); +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4); + +static int device_cmp(struct nf_conn *i, void *ifindex) +{ + const struct nf_conn_nat *nat = nfct_nat(i); + + if (!nat) + return 0; + if (nf_ct_l3num(i) != NFPROTO_IPV4) + 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 = netdev_notifier_info_to_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, 0, 0); + } + + 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; + struct netdev_notifier_info info; + + netdev_notifier_info_init(&info, dev); + return masq_device_event(this, event, &info); +} + +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 atomic_t masquerade_notifier_refcount = ATOMIC_INIT(0); + +void nf_nat_masquerade_ipv4_register_notifier(void) +{ + /* check if the notifier was already set */ + if (atomic_inc_return(&masquerade_notifier_refcount) > 1) + return; + + /* Register for device down reports */ + register_netdevice_notifier(&masq_dev_notifier); + /* Register IP address change reports */ + register_inetaddr_notifier(&masq_inet_notifier); +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_register_notifier); + +void nf_nat_masquerade_ipv4_unregister_notifier(void) +{ + /* check if the notifier still has clients */ + if (atomic_dec_return(&masquerade_notifier_refcount) > 0) + return; + + unregister_netdevice_notifier(&masq_dev_notifier); + unregister_inetaddr_notifier(&masq_inet_notifier); +} +EXPORT_SYMBOL_GPL(nf_nat_masquerade_ipv4_unregister_notifier); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>"); |