[NETFILTER]: nf_nat: pass manip type instead of hook to nf_nat_setup_info
[linux-2.6.git] / net / ipv4 / netfilter / nf_nat_rule.c
1 /* (C) 1999-2001 Paul `Rusty' Russell
2  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8
9 /* Everything about the rules for NAT. */
10 #include <linux/types.h>
11 #include <linux/ip.h>
12 #include <linux/netfilter.h>
13 #include <linux/netfilter_ipv4.h>
14 #include <linux/module.h>
15 #include <linux/kmod.h>
16 #include <linux/skbuff.h>
17 #include <linux/proc_fs.h>
18 #include <net/checksum.h>
19 #include <net/route.h>
20 #include <linux/bitops.h>
21
22 #include <linux/netfilter_ipv4/ip_tables.h>
23 #include <net/netfilter/nf_nat.h>
24 #include <net/netfilter/nf_nat_core.h>
25 #include <net/netfilter/nf_nat_rule.h>
26
27 #define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
28                          (1 << NF_INET_POST_ROUTING) | \
29                          (1 << NF_INET_LOCAL_OUT))
30
31 static struct
32 {
33         struct ipt_replace repl;
34         struct ipt_standard entries[3];
35         struct ipt_error term;
36 } nat_initial_table __initdata = {
37         .repl = {
38                 .name = "nat",
39                 .valid_hooks = NAT_VALID_HOOKS,
40                 .num_entries = 4,
41                 .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
42                 .hook_entry = {
43                         [NF_INET_PRE_ROUTING] = 0,
44                         [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
45                         [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
46                 },
47                 .underflow = {
48                         [NF_INET_PRE_ROUTING] = 0,
49                         [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard),
50                         [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2
51                 },
52         },
53         .entries = {
54                 IPT_STANDARD_INIT(NF_ACCEPT),   /* PRE_ROUTING */
55                 IPT_STANDARD_INIT(NF_ACCEPT),   /* POST_ROUTING */
56                 IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_OUT */
57         },
58         .term = IPT_ERROR_INIT,                 /* ERROR */
59 };
60
61 static struct xt_table nat_table = {
62         .name           = "nat",
63         .valid_hooks    = NAT_VALID_HOOKS,
64         .lock           = RW_LOCK_UNLOCKED,
65         .me             = THIS_MODULE,
66         .af             = AF_INET,
67 };
68
69 /* Source NAT */
70 static unsigned int ipt_snat_target(struct sk_buff *skb,
71                                     const struct net_device *in,
72                                     const struct net_device *out,
73                                     unsigned int hooknum,
74                                     const struct xt_target *target,
75                                     const void *targinfo)
76 {
77         struct nf_conn *ct;
78         enum ip_conntrack_info ctinfo;
79         const struct nf_nat_multi_range_compat *mr = targinfo;
80
81         NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING);
82
83         ct = nf_ct_get(skb, &ctinfo);
84
85         /* Connection must be valid and new. */
86         NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
87                             ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
88         NF_CT_ASSERT(out);
89
90         return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC);
91 }
92
93 /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */
94 static void warn_if_extra_mangle(__be32 dstip, __be32 srcip)
95 {
96         static int warned = 0;
97         struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } };
98         struct rtable *rt;
99
100         if (ip_route_output_key(&rt, &fl) != 0)
101                 return;
102
103         if (rt->rt_src != srcip && !warned) {
104                 printk("NAT: no longer support implicit source local NAT\n");
105                 printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n",
106                        NIPQUAD(srcip), NIPQUAD(dstip));
107                 warned = 1;
108         }
109         ip_rt_put(rt);
110 }
111
112 static unsigned int ipt_dnat_target(struct sk_buff *skb,
113                                     const struct net_device *in,
114                                     const struct net_device *out,
115                                     unsigned int hooknum,
116                                     const struct xt_target *target,
117                                     const void *targinfo)
118 {
119         struct nf_conn *ct;
120         enum ip_conntrack_info ctinfo;
121         const struct nf_nat_multi_range_compat *mr = targinfo;
122
123         NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING ||
124                      hooknum == NF_INET_LOCAL_OUT);
125
126         ct = nf_ct_get(skb, &ctinfo);
127
128         /* Connection must be valid and new. */
129         NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
130
131         if (hooknum == NF_INET_LOCAL_OUT &&
132             mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)
133                 warn_if_extra_mangle(ip_hdr(skb)->daddr,
134                                      mr->range[0].min_ip);
135
136         return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST);
137 }
138
139 static bool ipt_snat_checkentry(const char *tablename,
140                                 const void *entry,
141                                 const struct xt_target *target,
142                                 void *targinfo,
143                                 unsigned int hook_mask)
144 {
145         struct nf_nat_multi_range_compat *mr = targinfo;
146
147         /* Must be a valid range */
148         if (mr->rangesize != 1) {
149                 printk("SNAT: multiple ranges no longer supported\n");
150                 return false;
151         }
152         return true;
153 }
154
155 static bool ipt_dnat_checkentry(const char *tablename,
156                                 const void *entry,
157                                 const struct xt_target *target,
158                                 void *targinfo,
159                                 unsigned int hook_mask)
160 {
161         struct nf_nat_multi_range_compat *mr = targinfo;
162
163         /* Must be a valid range */
164         if (mr->rangesize != 1) {
165                 printk("DNAT: multiple ranges no longer supported\n");
166                 return false;
167         }
168         return true;
169 }
170
171 unsigned int
172 alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
173 {
174         /* Force range to this IP; let proto decide mapping for
175            per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
176            Use reply in case it's already been mangled (eg local packet).
177         */
178         __be32 ip
179                 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
180                    ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
181                    : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
182         struct nf_nat_range range
183                 = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } };
184
185         pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n",
186                  ct, NIPQUAD(ip));
187         return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
188 }
189
190 unsigned int
191 alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum)
192 {
193         __be32 ip
194                 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
195                    ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip
196                    : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip);
197         __be16 all
198                 = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC
199                    ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all
200                    : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all);
201         struct nf_nat_range range
202                 = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } };
203
204         pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n",
205                  ct, NIPQUAD(ip));
206         return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum));
207 }
208
209 int nf_nat_rule_find(struct sk_buff *skb,
210                      unsigned int hooknum,
211                      const struct net_device *in,
212                      const struct net_device *out,
213                      struct nf_conn *ct)
214 {
215         int ret;
216
217         ret = ipt_do_table(skb, hooknum, in, out, &nat_table);
218
219         if (ret == NF_ACCEPT) {
220                 if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum)))
221                         /* NUL mapping */
222                         ret = alloc_null_binding(ct, hooknum);
223         }
224         return ret;
225 }
226
227 static struct xt_target ipt_snat_reg __read_mostly = {
228         .name           = "SNAT",
229         .target         = ipt_snat_target,
230         .targetsize     = sizeof(struct nf_nat_multi_range_compat),
231         .table          = "nat",
232         .hooks          = 1 << NF_INET_POST_ROUTING,
233         .checkentry     = ipt_snat_checkentry,
234         .family         = AF_INET,
235 };
236
237 static struct xt_target ipt_dnat_reg __read_mostly = {
238         .name           = "DNAT",
239         .target         = ipt_dnat_target,
240         .targetsize     = sizeof(struct nf_nat_multi_range_compat),
241         .table          = "nat",
242         .hooks          = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
243         .checkentry     = ipt_dnat_checkentry,
244         .family         = AF_INET,
245 };
246
247 int __init nf_nat_rule_init(void)
248 {
249         int ret;
250
251         ret = ipt_register_table(&nat_table, &nat_initial_table.repl);
252         if (ret != 0)
253                 return ret;
254         ret = xt_register_target(&ipt_snat_reg);
255         if (ret != 0)
256                 goto unregister_table;
257
258         ret = xt_register_target(&ipt_dnat_reg);
259         if (ret != 0)
260                 goto unregister_snat;
261
262         return ret;
263
264  unregister_snat:
265         xt_unregister_target(&ipt_snat_reg);
266  unregister_table:
267         ipt_unregister_table(&nat_table);
268
269         return ret;
270 }
271
272 void nf_nat_rule_cleanup(void)
273 {
274         xt_unregister_target(&ipt_dnat_reg);
275         xt_unregister_target(&ipt_snat_reg);
276         ipt_unregister_table(&nat_table);
277 }