Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* Masquerade. Simple mapping which alters range to a local IP address |
2 | (depending on route). */ | |
3 | ||
4 | /* (C) 1999-2001 Paul `Rusty' Russell | |
5b1158e9 | 5 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> |
1da177e4 LT |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
1da177e4 | 12 | #include <linux/types.h> |
14c85021 | 13 | #include <linux/inetdevice.h> |
1da177e4 LT |
14 | #include <linux/ip.h> |
15 | #include <linux/timer.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/netfilter.h> | |
18 | #include <net/protocol.h> | |
19 | #include <net/ip.h> | |
20 | #include <net/checksum.h> | |
14c85021 | 21 | #include <net/route.h> |
5b1158e9 | 22 | #include <net/netfilter/nf_nat_rule.h> |
587aa641 | 23 | #include <linux/netfilter_ipv4.h> |
6709dbbb | 24 | #include <linux/netfilter/x_tables.h> |
1da177e4 LT |
25 | |
26 | MODULE_LICENSE("GPL"); | |
27 | MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); | |
2ae15b64 | 28 | MODULE_DESCRIPTION("Xtables: automatic-address SNAT"); |
1da177e4 | 29 | |
1da177e4 | 30 | /* Lock protects masq region inside conntrack */ |
e45b1be8 | 31 | static DEFINE_RWLOCK(masq_lock); |
1da177e4 LT |
32 | |
33 | /* FIXME: Multiple targets. --RR */ | |
e1931b78 | 34 | static bool |
d3c5ee6d JE |
35 | masquerade_tg_check(const char *tablename, const void *e, |
36 | const struct xt_target *target, void *targinfo, | |
37 | unsigned int hook_mask) | |
1da177e4 | 38 | { |
587aa641 | 39 | const struct nf_nat_multi_range_compat *mr = targinfo; |
1da177e4 | 40 | |
1da177e4 | 41 | if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) { |
0d53778e | 42 | pr_debug("masquerade_check: bad MAP_IPS.\n"); |
e1931b78 | 43 | return false; |
1da177e4 LT |
44 | } |
45 | if (mr->rangesize != 1) { | |
0d53778e | 46 | pr_debug("masquerade_check: bad rangesize %u\n", mr->rangesize); |
e1931b78 | 47 | return false; |
1da177e4 | 48 | } |
e1931b78 | 49 | return true; |
1da177e4 LT |
50 | } |
51 | ||
52 | static unsigned int | |
d3c5ee6d JE |
53 | masquerade_tg(struct sk_buff *skb, const struct net_device *in, |
54 | const struct net_device *out, unsigned int hooknum, | |
55 | const struct xt_target *target, const void *targinfo) | |
1da177e4 | 56 | { |
587aa641 | 57 | struct nf_conn *ct; |
5b1158e9 | 58 | struct nf_conn_nat *nat; |
1da177e4 | 59 | enum ip_conntrack_info ctinfo; |
587aa641 PM |
60 | struct nf_nat_range newrange; |
61 | const struct nf_nat_multi_range_compat *mr; | |
a47362a2 | 62 | const struct rtable *rt; |
a61ced5d | 63 | __be32 newsrc; |
1da177e4 | 64 | |
6e23ae2a | 65 | NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING); |
1da177e4 | 66 | |
3db05fea | 67 | ct = nf_ct_get(skb, &ctinfo); |
5b1158e9 | 68 | nat = nfct_nat(ct); |
587aa641 PM |
69 | |
70 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED | |
e905a9ed | 71 | || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); |
1da177e4 | 72 | |
adcb5ad1 PM |
73 | /* Source address is 0.0.0.0 - locally generated packet that is |
74 | * probably not supposed to be masqueraded. | |
75 | */ | |
5b1158e9 | 76 | if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0) |
adcb5ad1 PM |
77 | return NF_ACCEPT; |
78 | ||
1da177e4 | 79 | mr = targinfo; |
ee6b9673 | 80 | rt = skb->rtable; |
1da177e4 LT |
81 | newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE); |
82 | if (!newsrc) { | |
83 | printk("MASQUERADE: %s ate my IP address\n", out->name); | |
84 | return NF_DROP; | |
85 | } | |
86 | ||
e45b1be8 | 87 | write_lock_bh(&masq_lock); |
5b1158e9 | 88 | nat->masq_index = out->ifindex; |
e45b1be8 | 89 | write_unlock_bh(&masq_lock); |
1da177e4 LT |
90 | |
91 | /* Transfer from original range. */ | |
587aa641 | 92 | newrange = ((struct nf_nat_range) |
1da177e4 LT |
93 | { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS, |
94 | newsrc, newsrc, | |
95 | mr->range[0].min, mr->range[0].max }); | |
96 | ||
97 | /* Hand modified range to generic setup. */ | |
cc01dcbd | 98 | return nf_nat_setup_info(ct, &newrange, IP_NAT_MANIP_SRC); |
1da177e4 LT |
99 | } |
100 | ||
170b197c | 101 | static int |
587aa641 | 102 | device_cmp(struct nf_conn *i, void *ifindex) |
1da177e4 | 103 | { |
a47362a2 | 104 | const struct nf_conn_nat *nat = nfct_nat(i); |
587aa641 | 105 | int ret; |
bbdc176a MJ |
106 | |
107 | if (!nat) | |
108 | return 0; | |
1da177e4 | 109 | |
e45b1be8 | 110 | read_lock_bh(&masq_lock); |
5b1158e9 | 111 | ret = (nat->masq_index == (int)(long)ifindex); |
e45b1be8 | 112 | read_unlock_bh(&masq_lock); |
1da177e4 LT |
113 | |
114 | return ret; | |
115 | } | |
116 | ||
117 | static int masq_device_event(struct notifier_block *this, | |
118 | unsigned long event, | |
119 | void *ptr) | |
120 | { | |
a47362a2 | 121 | const struct net_device *dev = ptr; |
1da177e4 | 122 | |
e9dc8653 EB |
123 | if (dev->nd_net != &init_net) |
124 | return NOTIFY_DONE; | |
125 | ||
1da177e4 LT |
126 | if (event == NETDEV_DOWN) { |
127 | /* Device was downed. Search entire table for | |
128 | conntracks which were associated with that device, | |
129 | and forget them. */ | |
587aa641 | 130 | NF_CT_ASSERT(dev->ifindex != 0); |
1da177e4 | 131 | |
587aa641 | 132 | nf_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex); |
1da177e4 LT |
133 | } |
134 | ||
135 | return NOTIFY_DONE; | |
136 | } | |
137 | ||
138 | static int masq_inet_event(struct notifier_block *this, | |
139 | unsigned long event, | |
140 | void *ptr) | |
141 | { | |
6fc68624 DL |
142 | struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev; |
143 | return masq_device_event(this, event, dev); | |
1da177e4 LT |
144 | } |
145 | ||
146 | static struct notifier_block masq_dev_notifier = { | |
147 | .notifier_call = masq_device_event, | |
148 | }; | |
149 | ||
150 | static struct notifier_block masq_inet_notifier = { | |
151 | .notifier_call = masq_inet_event, | |
152 | }; | |
153 | ||
d3c5ee6d | 154 | static struct xt_target masquerade_tg_reg __read_mostly = { |
1da177e4 | 155 | .name = "MASQUERADE", |
6709dbbb | 156 | .family = AF_INET, |
d3c5ee6d | 157 | .target = masquerade_tg, |
587aa641 | 158 | .targetsize = sizeof(struct nf_nat_multi_range_compat), |
1d5cd909 | 159 | .table = "nat", |
6e23ae2a | 160 | .hooks = 1 << NF_INET_POST_ROUTING, |
d3c5ee6d | 161 | .checkentry = masquerade_tg_check, |
1da177e4 LT |
162 | .me = THIS_MODULE, |
163 | }; | |
164 | ||
d3c5ee6d | 165 | static int __init masquerade_tg_init(void) |
1da177e4 LT |
166 | { |
167 | int ret; | |
168 | ||
d3c5ee6d | 169 | ret = xt_register_target(&masquerade_tg_reg); |
1da177e4 LT |
170 | |
171 | if (ret == 0) { | |
172 | /* Register for device down reports */ | |
173 | register_netdevice_notifier(&masq_dev_notifier); | |
174 | /* Register IP address change reports */ | |
175 | register_inetaddr_notifier(&masq_inet_notifier); | |
176 | } | |
177 | ||
178 | return ret; | |
179 | } | |
180 | ||
d3c5ee6d | 181 | static void __exit masquerade_tg_exit(void) |
1da177e4 | 182 | { |
d3c5ee6d | 183 | xt_unregister_target(&masquerade_tg_reg); |
1da177e4 | 184 | unregister_netdevice_notifier(&masq_dev_notifier); |
e905a9ed | 185 | unregister_inetaddr_notifier(&masq_inet_notifier); |
1da177e4 LT |
186 | } |
187 | ||
d3c5ee6d JE |
188 | module_init(masquerade_tg_init); |
189 | module_exit(masquerade_tg_exit); |