Commit | Line | Data |
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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>"); | |
28 | MODULE_DESCRIPTION("iptables MASQUERADE target module"); | |
29 | ||
30 | #if 0 | |
31 | #define DEBUGP printk | |
32 | #else | |
33 | #define DEBUGP(format, args...) | |
34 | #endif | |
35 | ||
36 | /* Lock protects masq region inside conntrack */ | |
e45b1be8 | 37 | static DEFINE_RWLOCK(masq_lock); |
1da177e4 LT |
38 | |
39 | /* FIXME: Multiple targets. --RR */ | |
e1931b78 | 40 | static bool |
1da177e4 | 41 | masquerade_check(const char *tablename, |
2e4e6a17 | 42 | const void *e, |
c4986734 | 43 | const struct xt_target *target, |
1da177e4 | 44 | void *targinfo, |
1da177e4 LT |
45 | unsigned int hook_mask) |
46 | { | |
587aa641 | 47 | const struct nf_nat_multi_range_compat *mr = targinfo; |
1da177e4 | 48 | |
1da177e4 LT |
49 | if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) { |
50 | DEBUGP("masquerade_check: bad MAP_IPS.\n"); | |
e1931b78 | 51 | return false; |
1da177e4 LT |
52 | } |
53 | if (mr->rangesize != 1) { | |
54 | DEBUGP("masquerade_check: bad rangesize %u.\n", mr->rangesize); | |
e1931b78 | 55 | return false; |
1da177e4 | 56 | } |
e1931b78 | 57 | return true; |
1da177e4 LT |
58 | } |
59 | ||
60 | static unsigned int | |
61 | masquerade_target(struct sk_buff **pskb, | |
62 | const struct net_device *in, | |
63 | const struct net_device *out, | |
64 | unsigned int hooknum, | |
c4986734 | 65 | const struct xt_target *target, |
fe1cb108 | 66 | const void *targinfo) |
1da177e4 | 67 | { |
587aa641 | 68 | struct nf_conn *ct; |
5b1158e9 | 69 | struct nf_conn_nat *nat; |
1da177e4 | 70 | enum ip_conntrack_info ctinfo; |
587aa641 PM |
71 | struct nf_nat_range newrange; |
72 | const struct nf_nat_multi_range_compat *mr; | |
1da177e4 | 73 | struct rtable *rt; |
a61ced5d | 74 | __be32 newsrc; |
1da177e4 | 75 | |
587aa641 | 76 | NF_CT_ASSERT(hooknum == NF_IP_POST_ROUTING); |
1da177e4 | 77 | |
587aa641 | 78 | ct = nf_ct_get(*pskb, &ctinfo); |
5b1158e9 | 79 | nat = nfct_nat(ct); |
587aa641 PM |
80 | |
81 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED | |
e905a9ed | 82 | || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); |
1da177e4 | 83 | |
adcb5ad1 PM |
84 | /* Source address is 0.0.0.0 - locally generated packet that is |
85 | * probably not supposed to be masqueraded. | |
86 | */ | |
5b1158e9 | 87 | if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0) |
adcb5ad1 PM |
88 | return NF_ACCEPT; |
89 | ||
1da177e4 LT |
90 | mr = targinfo; |
91 | rt = (struct rtable *)(*pskb)->dst; | |
92 | newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE); | |
93 | if (!newsrc) { | |
94 | printk("MASQUERADE: %s ate my IP address\n", out->name); | |
95 | return NF_DROP; | |
96 | } | |
97 | ||
e45b1be8 | 98 | write_lock_bh(&masq_lock); |
5b1158e9 | 99 | nat->masq_index = out->ifindex; |
e45b1be8 | 100 | write_unlock_bh(&masq_lock); |
1da177e4 LT |
101 | |
102 | /* Transfer from original range. */ | |
587aa641 | 103 | newrange = ((struct nf_nat_range) |
1da177e4 LT |
104 | { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS, |
105 | newsrc, newsrc, | |
106 | mr->range[0].min, mr->range[0].max }); | |
107 | ||
108 | /* Hand modified range to generic setup. */ | |
587aa641 | 109 | return nf_nat_setup_info(ct, &newrange, hooknum); |
1da177e4 LT |
110 | } |
111 | ||
112 | static inline int | |
587aa641 | 113 | device_cmp(struct nf_conn *i, void *ifindex) |
1da177e4 | 114 | { |
5b1158e9 | 115 | struct nf_conn_nat *nat = nfct_nat(i); |
587aa641 | 116 | int ret; |
bbdc176a MJ |
117 | |
118 | if (!nat) | |
119 | return 0; | |
1da177e4 | 120 | |
e45b1be8 | 121 | read_lock_bh(&masq_lock); |
5b1158e9 | 122 | ret = (nat->masq_index == (int)(long)ifindex); |
e45b1be8 | 123 | read_unlock_bh(&masq_lock); |
1da177e4 LT |
124 | |
125 | return ret; | |
126 | } | |
127 | ||
128 | static int masq_device_event(struct notifier_block *this, | |
129 | unsigned long event, | |
130 | void *ptr) | |
131 | { | |
132 | struct net_device *dev = ptr; | |
133 | ||
134 | if (event == NETDEV_DOWN) { | |
135 | /* Device was downed. Search entire table for | |
136 | conntracks which were associated with that device, | |
137 | and forget them. */ | |
587aa641 | 138 | NF_CT_ASSERT(dev->ifindex != 0); |
1da177e4 | 139 | |
587aa641 | 140 | nf_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex); |
1da177e4 LT |
141 | } |
142 | ||
143 | return NOTIFY_DONE; | |
144 | } | |
145 | ||
146 | static int masq_inet_event(struct notifier_block *this, | |
147 | unsigned long event, | |
148 | void *ptr) | |
149 | { | |
150 | struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev; | |
151 | ||
152 | if (event == NETDEV_DOWN) { | |
153 | /* IP address was deleted. Search entire table for | |
154 | conntracks which were associated with that device, | |
155 | and forget them. */ | |
587aa641 | 156 | NF_CT_ASSERT(dev->ifindex != 0); |
1da177e4 | 157 | |
587aa641 | 158 | nf_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex); |
1da177e4 LT |
159 | } |
160 | ||
161 | return NOTIFY_DONE; | |
162 | } | |
163 | ||
164 | static struct notifier_block masq_dev_notifier = { | |
165 | .notifier_call = masq_device_event, | |
166 | }; | |
167 | ||
168 | static struct notifier_block masq_inet_notifier = { | |
169 | .notifier_call = masq_inet_event, | |
170 | }; | |
171 | ||
6709dbbb | 172 | static struct xt_target masquerade = { |
1da177e4 | 173 | .name = "MASQUERADE", |
6709dbbb | 174 | .family = AF_INET, |
1da177e4 | 175 | .target = masquerade_target, |
587aa641 | 176 | .targetsize = sizeof(struct nf_nat_multi_range_compat), |
1d5cd909 PM |
177 | .table = "nat", |
178 | .hooks = 1 << NF_IP_POST_ROUTING, | |
1da177e4 LT |
179 | .checkentry = masquerade_check, |
180 | .me = THIS_MODULE, | |
181 | }; | |
182 | ||
65b4b4e8 | 183 | static int __init ipt_masquerade_init(void) |
1da177e4 LT |
184 | { |
185 | int ret; | |
186 | ||
6709dbbb | 187 | ret = xt_register_target(&masquerade); |
1da177e4 LT |
188 | |
189 | if (ret == 0) { | |
190 | /* Register for device down reports */ | |
191 | register_netdevice_notifier(&masq_dev_notifier); | |
192 | /* Register IP address change reports */ | |
193 | register_inetaddr_notifier(&masq_inet_notifier); | |
194 | } | |
195 | ||
196 | return ret; | |
197 | } | |
198 | ||
65b4b4e8 | 199 | static void __exit ipt_masquerade_fini(void) |
1da177e4 | 200 | { |
6709dbbb | 201 | xt_unregister_target(&masquerade); |
1da177e4 | 202 | unregister_netdevice_notifier(&masq_dev_notifier); |
e905a9ed | 203 | unregister_inetaddr_notifier(&masq_inet_notifier); |
1da177e4 LT |
204 | } |
205 | ||
65b4b4e8 AM |
206 | module_init(ipt_masquerade_init); |
207 | module_exit(ipt_masquerade_fini); |