[NETFILTER]: Remove changelogs and CVS IDs
[linux-2.6.git] / net / ipv4 / netfilter / ipt_SAME.c
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.
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>
22 #include <linux/netfilter/x_tables.h>
23 #include <net/netfilter/nf_nat_rule.h>
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
36 static int
37 same_check(const char *tablename,
38               const void *e,
39               const struct xt_target *target,
40               void *targinfo,
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
48         if (mr->rangesize < 1) {
49                 DEBUGP("same_check: need at least one dest range.\n");
50                 return 0;
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);
56                 return 0;
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));
65                         return 0;
66                 }
67                 if (!(mr->range[count].flags & IP_NAT_RANGE_MAP_IPS)) {
68                         DEBUGP("same_check: bad MAP_IPS.\n");
69                         return 0;
70                 }
71                 rangeip = (ntohl(mr->range[count].max_ip) -
72                                         ntohl(mr->range[count].min_ip) + 1);
73                 mr->ipnum += rangeip;
74
75                 DEBUGP("same_check: range %u, ipnum = %u\n", count, rangeip);
76         }
77         DEBUGP("same_check: total ipaddresses = %u\n", mr->ipnum);
78
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 "
82                         "for %u ipaddresses!\n",
83                         (sizeof(u_int32_t) * mr->ipnum), mr->ipnum);
84                 return 0;
85         }
86         DEBUGP("same_check: Allocated %u bytes for %u ipaddresses.\n",
87                         (sizeof(u_int32_t) * mr->ipnum), mr->ipnum);
88
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         }
100         return 1;
101 }
102
103 static void
104 same_destroy(const struct xt_target *target, void *targinfo)
105 {
106         struct ipt_same_info *mr = targinfo;
107
108         kfree(mr->iparray);
109
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,
119                 const struct xt_target *target,
120                 const void *targinfo)
121 {
122         struct nf_conn *ct;
123         enum ip_conntrack_info ctinfo;
124         u_int32_t tmpip, aindex;
125         __be32 new_ip;
126         const struct ipt_same_info *same = targinfo;
127         struct nf_nat_range newrange;
128         const struct nf_conntrack_tuple *t;
129
130         NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING ||
131                         hooknum == NF_IP_POST_ROUTING);
132         ct = nf_ct_get(*pskb, &ctinfo);
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 */
140
141         tmpip = ntohl(t->src.u3.ip);
142
143         if (!(same->info & IPT_SAME_NODST))
144                 tmpip += ntohl(t->dst.u3.ip);
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. */
155         newrange = ((struct nf_nat_range)
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. */
161         return nf_nat_setup_info(ct, &newrange, hooknum);
162 }
163
164 static struct xt_target same_reg = {
165         .name           = "SAME",
166         .family         = AF_INET,
167         .target         = same_target,
168         .targetsize     = sizeof(struct ipt_same_info),
169         .table          = "nat",
170         .hooks          = (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_POST_ROUTING),
171         .checkentry     = same_check,
172         .destroy        = same_destroy,
173         .me             = THIS_MODULE,
174 };
175
176 static int __init ipt_same_init(void)
177 {
178         return xt_register_target(&same_reg);
179 }
180
181 static void __exit ipt_same_fini(void)
182 {
183         xt_unregister_target(&same_reg);
184 }
185
186 module_init(ipt_same_init);
187 module_exit(ipt_same_fini);
188