Jozsef Kadlecsik | 5b1158e | 2006-12-02 22:07:13 -0800 | [diff] [blame^] | 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 | #if 0 |
| 28 | #define DEBUGP printk |
| 29 | #else |
| 30 | #define DEBUGP(format, args...) |
| 31 | #endif |
| 32 | |
| 33 | #define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_LOCAL_OUT)) |
| 34 | |
| 35 | static struct |
| 36 | { |
| 37 | struct ipt_replace repl; |
| 38 | struct ipt_standard entries[3]; |
| 39 | struct ipt_error term; |
| 40 | } nat_initial_table __initdata = { |
| 41 | .repl = { |
| 42 | .name = "nat", |
| 43 | .valid_hooks = NAT_VALID_HOOKS, |
| 44 | .num_entries = 4, |
| 45 | .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), |
| 46 | .hook_entry = { |
| 47 | [NF_IP_PRE_ROUTING] = 0, |
| 48 | [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard), |
| 49 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 }, |
| 50 | .underflow = { |
| 51 | [NF_IP_PRE_ROUTING] = 0, |
| 52 | [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard), |
| 53 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 }, |
| 54 | }, |
| 55 | .entries = { |
| 56 | /* PRE_ROUTING */ |
| 57 | { |
| 58 | .entry = { |
| 59 | .target_offset = sizeof(struct ipt_entry), |
| 60 | .next_offset = sizeof(struct ipt_standard), |
| 61 | }, |
| 62 | .target = { |
| 63 | .target = { |
| 64 | .u = { |
| 65 | .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)), |
| 66 | }, |
| 67 | }, |
| 68 | .verdict = -NF_ACCEPT - 1, |
| 69 | }, |
| 70 | }, |
| 71 | /* POST_ROUTING */ |
| 72 | { |
| 73 | .entry = { |
| 74 | .target_offset = sizeof(struct ipt_entry), |
| 75 | .next_offset = sizeof(struct ipt_standard), |
| 76 | }, |
| 77 | .target = { |
| 78 | .target = { |
| 79 | .u = { |
| 80 | .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)), |
| 81 | }, |
| 82 | }, |
| 83 | .verdict = -NF_ACCEPT - 1, |
| 84 | }, |
| 85 | }, |
| 86 | /* LOCAL_OUT */ |
| 87 | { |
| 88 | .entry = { |
| 89 | .target_offset = sizeof(struct ipt_entry), |
| 90 | .next_offset = sizeof(struct ipt_standard), |
| 91 | }, |
| 92 | .target = { |
| 93 | .target = { |
| 94 | .u = { |
| 95 | .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)), |
| 96 | }, |
| 97 | }, |
| 98 | .verdict = -NF_ACCEPT - 1, |
| 99 | }, |
| 100 | }, |
| 101 | }, |
| 102 | /* ERROR */ |
| 103 | .term = { |
| 104 | .entry = { |
| 105 | .target_offset = sizeof(struct ipt_entry), |
| 106 | .next_offset = sizeof(struct ipt_error), |
| 107 | }, |
| 108 | .target = { |
| 109 | .target = { |
| 110 | .u = { |
| 111 | .user = { |
| 112 | .target_size = IPT_ALIGN(sizeof(struct ipt_error_target)), |
| 113 | .name = IPT_ERROR_TARGET, |
| 114 | }, |
| 115 | }, |
| 116 | }, |
| 117 | .errorname = "ERROR", |
| 118 | }, |
| 119 | } |
| 120 | }; |
| 121 | |
| 122 | static struct ipt_table nat_table = { |
| 123 | .name = "nat", |
| 124 | .valid_hooks = NAT_VALID_HOOKS, |
| 125 | .lock = RW_LOCK_UNLOCKED, |
| 126 | .me = THIS_MODULE, |
| 127 | .af = AF_INET, |
| 128 | }; |
| 129 | |
| 130 | /* Source NAT */ |
| 131 | static unsigned int ipt_snat_target(struct sk_buff **pskb, |
| 132 | const struct net_device *in, |
| 133 | const struct net_device *out, |
| 134 | unsigned int hooknum, |
| 135 | const struct xt_target *target, |
| 136 | const void *targinfo) |
| 137 | { |
| 138 | struct nf_conn *ct; |
| 139 | enum ip_conntrack_info ctinfo; |
| 140 | const struct nf_nat_multi_range_compat *mr = targinfo; |
| 141 | |
| 142 | NF_CT_ASSERT(hooknum == NF_IP_POST_ROUTING); |
| 143 | |
| 144 | ct = nf_ct_get(*pskb, &ctinfo); |
| 145 | |
| 146 | /* Connection must be valid and new. */ |
| 147 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || |
| 148 | ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); |
| 149 | NF_CT_ASSERT(out); |
| 150 | |
| 151 | return nf_nat_setup_info(ct, &mr->range[0], hooknum); |
| 152 | } |
| 153 | |
| 154 | /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */ |
| 155 | static void warn_if_extra_mangle(__be32 dstip, __be32 srcip) |
| 156 | { |
| 157 | static int warned = 0; |
| 158 | struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } }; |
| 159 | struct rtable *rt; |
| 160 | |
| 161 | if (ip_route_output_key(&rt, &fl) != 0) |
| 162 | return; |
| 163 | |
| 164 | if (rt->rt_src != srcip && !warned) { |
| 165 | printk("NAT: no longer support implicit source local NAT\n"); |
| 166 | printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n", |
| 167 | NIPQUAD(srcip), NIPQUAD(dstip)); |
| 168 | warned = 1; |
| 169 | } |
| 170 | ip_rt_put(rt); |
| 171 | } |
| 172 | |
| 173 | static unsigned int ipt_dnat_target(struct sk_buff **pskb, |
| 174 | const struct net_device *in, |
| 175 | const struct net_device *out, |
| 176 | unsigned int hooknum, |
| 177 | const struct xt_target *target, |
| 178 | const void *targinfo) |
| 179 | { |
| 180 | struct nf_conn *ct; |
| 181 | enum ip_conntrack_info ctinfo; |
| 182 | const struct nf_nat_multi_range_compat *mr = targinfo; |
| 183 | |
| 184 | NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING || |
| 185 | hooknum == NF_IP_LOCAL_OUT); |
| 186 | |
| 187 | ct = nf_ct_get(*pskb, &ctinfo); |
| 188 | |
| 189 | /* Connection must be valid and new. */ |
| 190 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); |
| 191 | |
| 192 | if (hooknum == NF_IP_LOCAL_OUT && |
| 193 | mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) |
| 194 | warn_if_extra_mangle((*pskb)->nh.iph->daddr, |
| 195 | mr->range[0].min_ip); |
| 196 | |
| 197 | return nf_nat_setup_info(ct, &mr->range[0], hooknum); |
| 198 | } |
| 199 | |
| 200 | static int ipt_snat_checkentry(const char *tablename, |
| 201 | const void *entry, |
| 202 | const struct xt_target *target, |
| 203 | void *targinfo, |
| 204 | unsigned int hook_mask) |
| 205 | { |
| 206 | struct nf_nat_multi_range_compat *mr = targinfo; |
| 207 | |
| 208 | /* Must be a valid range */ |
| 209 | if (mr->rangesize != 1) { |
| 210 | printk("SNAT: multiple ranges no longer supported\n"); |
| 211 | return 0; |
| 212 | } |
| 213 | return 1; |
| 214 | } |
| 215 | |
| 216 | static int ipt_dnat_checkentry(const char *tablename, |
| 217 | const void *entry, |
| 218 | const struct xt_target *target, |
| 219 | void *targinfo, |
| 220 | unsigned int hook_mask) |
| 221 | { |
| 222 | struct nf_nat_multi_range_compat *mr = targinfo; |
| 223 | |
| 224 | /* Must be a valid range */ |
| 225 | if (mr->rangesize != 1) { |
| 226 | printk("DNAT: multiple ranges no longer supported\n"); |
| 227 | return 0; |
| 228 | } |
| 229 | return 1; |
| 230 | } |
| 231 | |
| 232 | inline unsigned int |
| 233 | alloc_null_binding(struct nf_conn *ct, |
| 234 | struct nf_nat_info *info, |
| 235 | unsigned int hooknum) |
| 236 | { |
| 237 | /* Force range to this IP; let proto decide mapping for |
| 238 | per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). |
| 239 | Use reply in case it's already been mangled (eg local packet). |
| 240 | */ |
| 241 | __be32 ip |
| 242 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC |
| 243 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip |
| 244 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); |
| 245 | struct nf_nat_range range |
| 246 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } }; |
| 247 | |
| 248 | DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n", |
| 249 | ct, NIPQUAD(ip)); |
| 250 | return nf_nat_setup_info(ct, &range, hooknum); |
| 251 | } |
| 252 | |
| 253 | unsigned int |
| 254 | alloc_null_binding_confirmed(struct nf_conn *ct, |
| 255 | struct nf_nat_info *info, |
| 256 | unsigned int hooknum) |
| 257 | { |
| 258 | __be32 ip |
| 259 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC |
| 260 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip |
| 261 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); |
| 262 | u_int16_t all |
| 263 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC |
| 264 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all |
| 265 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all); |
| 266 | struct nf_nat_range range |
| 267 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } }; |
| 268 | |
| 269 | DEBUGP("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n", |
| 270 | ct, NIPQUAD(ip)); |
| 271 | return nf_nat_setup_info(ct, &range, hooknum); |
| 272 | } |
| 273 | |
| 274 | int nf_nat_rule_find(struct sk_buff **pskb, |
| 275 | unsigned int hooknum, |
| 276 | const struct net_device *in, |
| 277 | const struct net_device *out, |
| 278 | struct nf_conn *ct, |
| 279 | struct nf_nat_info *info) |
| 280 | { |
| 281 | int ret; |
| 282 | |
| 283 | ret = ipt_do_table(pskb, hooknum, in, out, &nat_table); |
| 284 | |
| 285 | if (ret == NF_ACCEPT) { |
| 286 | if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum))) |
| 287 | /* NUL mapping */ |
| 288 | ret = alloc_null_binding(ct, info, hooknum); |
| 289 | } |
| 290 | return ret; |
| 291 | } |
| 292 | |
| 293 | static struct ipt_target ipt_snat_reg = { |
| 294 | .name = "SNAT", |
| 295 | .target = ipt_snat_target, |
| 296 | .targetsize = sizeof(struct nf_nat_multi_range_compat), |
| 297 | .table = "nat", |
| 298 | .hooks = 1 << NF_IP_POST_ROUTING, |
| 299 | .checkentry = ipt_snat_checkentry, |
| 300 | .family = AF_INET, |
| 301 | }; |
| 302 | |
| 303 | static struct xt_target ipt_dnat_reg = { |
| 304 | .name = "DNAT", |
| 305 | .target = ipt_dnat_target, |
| 306 | .targetsize = sizeof(struct nf_nat_multi_range_compat), |
| 307 | .table = "nat", |
| 308 | .hooks = (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT), |
| 309 | .checkentry = ipt_dnat_checkentry, |
| 310 | .family = AF_INET, |
| 311 | }; |
| 312 | |
| 313 | int __init nf_nat_rule_init(void) |
| 314 | { |
| 315 | int ret; |
| 316 | |
| 317 | ret = ipt_register_table(&nat_table, &nat_initial_table.repl); |
| 318 | if (ret != 0) |
| 319 | return ret; |
| 320 | ret = xt_register_target(&ipt_snat_reg); |
| 321 | if (ret != 0) |
| 322 | goto unregister_table; |
| 323 | |
| 324 | ret = xt_register_target(&ipt_dnat_reg); |
| 325 | if (ret != 0) |
| 326 | goto unregister_snat; |
| 327 | |
| 328 | return ret; |
| 329 | |
| 330 | unregister_snat: |
| 331 | xt_unregister_target(&ipt_snat_reg); |
| 332 | unregister_table: |
| 333 | ipt_unregister_table(&nat_table); |
| 334 | |
| 335 | return ret; |
| 336 | } |
| 337 | |
| 338 | void nf_nat_rule_cleanup(void) |
| 339 | { |
| 340 | xt_unregister_target(&ipt_dnat_reg); |
| 341 | xt_unregister_target(&ipt_snat_reg); |
| 342 | ipt_unregister_table(&nat_table); |
| 343 | } |