Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* Same. Just like SNAT, only try to make the connections |
| 2 | * between client A and server B always have the same source ip. |
| 3 | * |
| 4 | * (C) 2000 Paul `Rusty' Russell |
| 5 | * (C) 2001 Martin Josefsson |
| 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. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 10 | */ |
| 11 | #include <linux/types.h> |
| 12 | #include <linux/ip.h> |
| 13 | #include <linux/timer.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/netfilter.h> |
| 16 | #include <linux/netdevice.h> |
| 17 | #include <linux/if.h> |
| 18 | #include <linux/inetdevice.h> |
| 19 | #include <net/protocol.h> |
| 20 | #include <net/checksum.h> |
| 21 | #include <linux/netfilter_ipv4.h> |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 22 | #include <linux/netfilter/x_tables.h> |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 23 | #include <net/netfilter/nf_nat_rule.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | #include <linux/netfilter_ipv4/ipt_SAME.h> |
| 25 | |
| 26 | MODULE_LICENSE("GPL"); |
| 27 | MODULE_AUTHOR("Martin Josefsson <gandalf@wlug.westbo.se>"); |
| 28 | MODULE_DESCRIPTION("iptables special SNAT module for consistent sourceip"); |
| 29 | |
| 30 | #if 0 |
| 31 | #define DEBUGP printk |
| 32 | #else |
| 33 | #define DEBUGP(format, args...) |
| 34 | #endif |
| 35 | |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame^] | 36 | static bool |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | same_check(const char *tablename, |
Harald Welte | 2e4e6a1 | 2006-01-12 13:30:04 -0800 | [diff] [blame] | 38 | const void *e, |
Patrick McHardy | c498673 | 2006-03-20 18:02:56 -0800 | [diff] [blame] | 39 | const struct xt_target *target, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 40 | void *targinfo, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | unsigned int hook_mask) |
| 42 | { |
| 43 | unsigned int count, countess, rangeip, index = 0; |
| 44 | struct ipt_same_info *mr = targinfo; |
| 45 | |
| 46 | mr->ipnum = 0; |
| 47 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | if (mr->rangesize < 1) { |
| 49 | DEBUGP("same_check: need at least one dest range.\n"); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame^] | 50 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | } |
| 52 | if (mr->rangesize > IPT_SAME_MAX_RANGE) { |
| 53 | DEBUGP("same_check: too many ranges specified, maximum " |
| 54 | "is %u ranges\n", |
| 55 | IPT_SAME_MAX_RANGE); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame^] | 56 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | } |
| 58 | for (count = 0; count < mr->rangesize; count++) { |
| 59 | if (ntohl(mr->range[count].min_ip) > |
| 60 | ntohl(mr->range[count].max_ip)) { |
| 61 | DEBUGP("same_check: min_ip is larger than max_ip in " |
| 62 | "range `%u.%u.%u.%u-%u.%u.%u.%u'.\n", |
| 63 | NIPQUAD(mr->range[count].min_ip), |
| 64 | NIPQUAD(mr->range[count].max_ip)); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame^] | 65 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | } |
| 67 | if (!(mr->range[count].flags & IP_NAT_RANGE_MAP_IPS)) { |
| 68 | DEBUGP("same_check: bad MAP_IPS.\n"); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame^] | 69 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 70 | } |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 71 | rangeip = (ntohl(mr->range[count].max_ip) - |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 72 | ntohl(mr->range[count].min_ip) + 1); |
| 73 | mr->ipnum += rangeip; |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 74 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | DEBUGP("same_check: range %u, ipnum = %u\n", count, rangeip); |
| 76 | } |
| 77 | DEBUGP("same_check: total ipaddresses = %u\n", mr->ipnum); |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 78 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 79 | mr->iparray = kmalloc((sizeof(u_int32_t) * mr->ipnum), GFP_KERNEL); |
| 80 | if (!mr->iparray) { |
| 81 | DEBUGP("same_check: Couldn't allocate %u bytes " |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 82 | "for %u ipaddresses!\n", |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 83 | (sizeof(u_int32_t) * mr->ipnum), mr->ipnum); |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame^] | 84 | return false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | } |
| 86 | DEBUGP("same_check: Allocated %u bytes for %u ipaddresses.\n", |
| 87 | (sizeof(u_int32_t) * mr->ipnum), mr->ipnum); |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 88 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 89 | for (count = 0; count < mr->rangesize; count++) { |
| 90 | for (countess = ntohl(mr->range[count].min_ip); |
| 91 | countess <= ntohl(mr->range[count].max_ip); |
| 92 | countess++) { |
| 93 | mr->iparray[index] = countess; |
| 94 | DEBUGP("same_check: Added ipaddress `%u.%u.%u.%u' " |
| 95 | "in index %u.\n", |
| 96 | HIPQUAD(countess), index); |
| 97 | index++; |
| 98 | } |
| 99 | } |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame^] | 100 | return true; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | } |
| 102 | |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 103 | static void |
Patrick McHardy | efa7416 | 2006-08-22 00:36:37 -0700 | [diff] [blame] | 104 | same_destroy(const struct xt_target *target, void *targinfo) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | { |
| 106 | struct ipt_same_info *mr = targinfo; |
| 107 | |
| 108 | kfree(mr->iparray); |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 109 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | DEBUGP("same_destroy: Deallocated %u bytes for %u ipaddresses.\n", |
| 111 | (sizeof(u_int32_t) * mr->ipnum), mr->ipnum); |
| 112 | } |
| 113 | |
| 114 | static unsigned int |
| 115 | same_target(struct sk_buff **pskb, |
| 116 | const struct net_device *in, |
| 117 | const struct net_device *out, |
| 118 | unsigned int hooknum, |
Patrick McHardy | c498673 | 2006-03-20 18:02:56 -0800 | [diff] [blame] | 119 | const struct xt_target *target, |
Patrick McHardy | fe1cb10 | 2006-08-22 00:35:47 -0700 | [diff] [blame] | 120 | const void *targinfo) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 121 | { |
Patrick McHardy | 587aa641 | 2007-03-14 16:37:25 -0700 | [diff] [blame] | 122 | struct nf_conn *ct; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 123 | enum ip_conntrack_info ctinfo; |
Al Viro | 6a19d61 | 2006-09-28 14:22:24 -0700 | [diff] [blame] | 124 | u_int32_t tmpip, aindex; |
| 125 | __be32 new_ip; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 126 | const struct ipt_same_info *same = targinfo; |
Patrick McHardy | 587aa641 | 2007-03-14 16:37:25 -0700 | [diff] [blame] | 127 | struct nf_nat_range newrange; |
| 128 | const struct nf_conntrack_tuple *t; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | |
Patrick McHardy | 587aa641 | 2007-03-14 16:37:25 -0700 | [diff] [blame] | 130 | NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | hooknum == NF_IP_POST_ROUTING); |
Patrick McHardy | 587aa641 | 2007-03-14 16:37:25 -0700 | [diff] [blame] | 132 | ct = nf_ct_get(*pskb, &ctinfo); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | |
| 134 | t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; |
| 135 | |
| 136 | /* Base new source on real src ip and optionally dst ip, |
| 137 | giving some hope for consistency across reboots. |
| 138 | Here we calculate the index in same->iparray which |
| 139 | holds the ipaddress we should use */ |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 140 | |
Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame] | 141 | tmpip = ntohl(t->src.u3.ip); |
| 142 | |
| 143 | if (!(same->info & IPT_SAME_NODST)) |
| 144 | tmpip += ntohl(t->dst.u3.ip); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 145 | aindex = tmpip % same->ipnum; |
| 146 | |
| 147 | new_ip = htonl(same->iparray[aindex]); |
| 148 | |
| 149 | DEBUGP("ipt_SAME: src=%u.%u.%u.%u dst=%u.%u.%u.%u, " |
| 150 | "new src=%u.%u.%u.%u\n", |
| 151 | NIPQUAD(t->src.ip), NIPQUAD(t->dst.ip), |
| 152 | NIPQUAD(new_ip)); |
| 153 | |
| 154 | /* Transfer from original range. */ |
Patrick McHardy | 587aa641 | 2007-03-14 16:37:25 -0700 | [diff] [blame] | 155 | newrange = ((struct nf_nat_range) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 156 | { same->range[0].flags, new_ip, new_ip, |
| 157 | /* FIXME: Use ports from correct range! */ |
| 158 | same->range[0].min, same->range[0].max }); |
| 159 | |
| 160 | /* Hand modified range to generic setup. */ |
Patrick McHardy | 587aa641 | 2007-03-14 16:37:25 -0700 | [diff] [blame] | 161 | return nf_nat_setup_info(ct, &newrange, hooknum); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 162 | } |
| 163 | |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 164 | static struct xt_target same_reg = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 165 | .name = "SAME", |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 166 | .family = AF_INET, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 167 | .target = same_target, |
Patrick McHardy | 1d5cd90 | 2006-03-20 18:01:14 -0800 | [diff] [blame] | 168 | .targetsize = sizeof(struct ipt_same_info), |
| 169 | .table = "nat", |
| 170 | .hooks = (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_POST_ROUTING), |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 171 | .checkentry = same_check, |
| 172 | .destroy = same_destroy, |
| 173 | .me = THIS_MODULE, |
| 174 | }; |
| 175 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 176 | static int __init ipt_same_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 177 | { |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 178 | return xt_register_target(&same_reg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 179 | } |
| 180 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 181 | static void __exit ipt_same_fini(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 182 | { |
Jan Engelhardt | 6709dbb | 2007-02-07 15:11:19 -0800 | [diff] [blame] | 183 | xt_unregister_target(&same_reg); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 184 | } |
| 185 | |
Andrew Morton | 65b4b4e | 2006-03-28 16:37:06 -0800 | [diff] [blame] | 186 | module_init(ipt_same_init); |
| 187 | module_exit(ipt_same_fini); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 188 | |