Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* (C) 1999-2001 Paul `Rusty' Russell |
| 2 | * (C) 2002-2004 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 | |
Patrick McHardy | e45b1be | 2005-06-21 14:01:30 -0700 | [diff] [blame] | 22 | #define ASSERT_READ_LOCK(x) |
| 23 | #define ASSERT_WRITE_LOCK(x) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | |
| 25 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 26 | #include <linux/netfilter_ipv4/ip_nat.h> |
| 27 | #include <linux/netfilter_ipv4/ip_nat_core.h> |
| 28 | #include <linux/netfilter_ipv4/ip_nat_rule.h> |
| 29 | #include <linux/netfilter_ipv4/listhelp.h> |
| 30 | |
| 31 | #if 0 |
| 32 | #define DEBUGP printk |
| 33 | #else |
| 34 | #define DEBUGP(format, args...) |
| 35 | #endif |
| 36 | |
| 37 | #define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_LOCAL_OUT)) |
| 38 | |
| 39 | static struct |
| 40 | { |
| 41 | struct ipt_replace repl; |
| 42 | struct ipt_standard entries[3]; |
| 43 | struct ipt_error term; |
| 44 | } nat_initial_table __initdata |
| 45 | = { { "nat", NAT_VALID_HOOKS, 4, |
| 46 | sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), |
| 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 | { [NF_IP_PRE_ROUTING] = 0, |
| 51 | [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard), |
| 52 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 }, |
| 53 | 0, NULL, { } }, |
| 54 | { |
| 55 | /* PRE_ROUTING */ |
| 56 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 57 | 0, |
| 58 | sizeof(struct ipt_entry), |
| 59 | sizeof(struct ipt_standard), |
| 60 | 0, { 0, 0 }, { } }, |
| 61 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, |
| 62 | -NF_ACCEPT - 1 } }, |
| 63 | /* POST_ROUTING */ |
| 64 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 65 | 0, |
| 66 | sizeof(struct ipt_entry), |
| 67 | sizeof(struct ipt_standard), |
| 68 | 0, { 0, 0 }, { } }, |
| 69 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, |
| 70 | -NF_ACCEPT - 1 } }, |
| 71 | /* LOCAL_OUT */ |
| 72 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 73 | 0, |
| 74 | sizeof(struct ipt_entry), |
| 75 | sizeof(struct ipt_standard), |
| 76 | 0, { 0, 0 }, { } }, |
| 77 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, |
| 78 | -NF_ACCEPT - 1 } } |
| 79 | }, |
| 80 | /* ERROR */ |
| 81 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, |
| 82 | 0, |
| 83 | sizeof(struct ipt_entry), |
| 84 | sizeof(struct ipt_error), |
| 85 | 0, { 0, 0 }, { } }, |
| 86 | { { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } }, |
| 87 | { } }, |
| 88 | "ERROR" |
| 89 | } |
| 90 | } |
| 91 | }; |
| 92 | |
| 93 | static struct ipt_table nat_table = { |
| 94 | .name = "nat", |
| 95 | .valid_hooks = NAT_VALID_HOOKS, |
| 96 | .lock = RW_LOCK_UNLOCKED, |
| 97 | .me = THIS_MODULE, |
| 98 | }; |
| 99 | |
| 100 | /* Source NAT */ |
| 101 | static unsigned int ipt_snat_target(struct sk_buff **pskb, |
| 102 | const struct net_device *in, |
| 103 | const struct net_device *out, |
| 104 | unsigned int hooknum, |
| 105 | const void *targinfo, |
| 106 | void *userinfo) |
| 107 | { |
| 108 | struct ip_conntrack *ct; |
| 109 | enum ip_conntrack_info ctinfo; |
| 110 | const struct ip_nat_multi_range_compat *mr = targinfo; |
| 111 | |
| 112 | IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING); |
| 113 | |
| 114 | ct = ip_conntrack_get(*pskb, &ctinfo); |
| 115 | |
| 116 | /* Connection must be valid and new. */ |
| 117 | IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED |
| 118 | || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); |
| 119 | IP_NF_ASSERT(out); |
| 120 | |
| 121 | return ip_nat_setup_info(ct, &mr->range[0], hooknum); |
| 122 | } |
| 123 | |
| 124 | /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */ |
| 125 | static void warn_if_extra_mangle(u32 dstip, u32 srcip) |
| 126 | { |
| 127 | static int warned = 0; |
| 128 | struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } }; |
| 129 | struct rtable *rt; |
| 130 | |
| 131 | if (ip_route_output_key(&rt, &fl) != 0) |
| 132 | return; |
| 133 | |
| 134 | if (rt->rt_src != srcip && !warned) { |
| 135 | printk("NAT: no longer support implicit source local NAT\n"); |
| 136 | printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n", |
| 137 | NIPQUAD(srcip), NIPQUAD(dstip)); |
| 138 | warned = 1; |
| 139 | } |
| 140 | ip_rt_put(rt); |
| 141 | } |
| 142 | |
| 143 | static unsigned int ipt_dnat_target(struct sk_buff **pskb, |
| 144 | const struct net_device *in, |
| 145 | const struct net_device *out, |
| 146 | unsigned int hooknum, |
| 147 | const void *targinfo, |
| 148 | void *userinfo) |
| 149 | { |
| 150 | struct ip_conntrack *ct; |
| 151 | enum ip_conntrack_info ctinfo; |
| 152 | const struct ip_nat_multi_range_compat *mr = targinfo; |
| 153 | |
| 154 | IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING |
| 155 | || hooknum == NF_IP_LOCAL_OUT); |
| 156 | |
| 157 | ct = ip_conntrack_get(*pskb, &ctinfo); |
| 158 | |
| 159 | /* Connection must be valid and new. */ |
| 160 | IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); |
| 161 | |
| 162 | if (hooknum == NF_IP_LOCAL_OUT |
| 163 | && mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) |
| 164 | warn_if_extra_mangle((*pskb)->nh.iph->daddr, |
| 165 | mr->range[0].min_ip); |
| 166 | |
| 167 | return ip_nat_setup_info(ct, &mr->range[0], hooknum); |
| 168 | } |
| 169 | |
| 170 | static int ipt_snat_checkentry(const char *tablename, |
| 171 | const struct ipt_entry *e, |
| 172 | void *targinfo, |
| 173 | unsigned int targinfosize, |
| 174 | unsigned int hook_mask) |
| 175 | { |
| 176 | struct ip_nat_multi_range_compat *mr = targinfo; |
| 177 | |
| 178 | /* Must be a valid range */ |
| 179 | if (mr->rangesize != 1) { |
| 180 | printk("SNAT: multiple ranges no longer supported\n"); |
| 181 | return 0; |
| 182 | } |
| 183 | |
| 184 | if (targinfosize != IPT_ALIGN(sizeof(struct ip_nat_multi_range_compat))) { |
| 185 | DEBUGP("SNAT: Target size %u wrong for %u ranges\n", |
| 186 | targinfosize, mr->rangesize); |
| 187 | return 0; |
| 188 | } |
| 189 | |
| 190 | /* Only allow these for NAT. */ |
| 191 | if (strcmp(tablename, "nat") != 0) { |
| 192 | DEBUGP("SNAT: wrong table %s\n", tablename); |
| 193 | return 0; |
| 194 | } |
| 195 | |
| 196 | if (hook_mask & ~(1 << NF_IP_POST_ROUTING)) { |
| 197 | DEBUGP("SNAT: hook mask 0x%x bad\n", hook_mask); |
| 198 | return 0; |
| 199 | } |
| 200 | return 1; |
| 201 | } |
| 202 | |
| 203 | static int ipt_dnat_checkentry(const char *tablename, |
| 204 | const struct ipt_entry *e, |
| 205 | void *targinfo, |
| 206 | unsigned int targinfosize, |
| 207 | unsigned int hook_mask) |
| 208 | { |
| 209 | struct ip_nat_multi_range_compat *mr = targinfo; |
| 210 | |
| 211 | /* Must be a valid range */ |
| 212 | if (mr->rangesize != 1) { |
| 213 | printk("DNAT: multiple ranges no longer supported\n"); |
| 214 | return 0; |
| 215 | } |
| 216 | |
| 217 | if (targinfosize != IPT_ALIGN(sizeof(struct ip_nat_multi_range_compat))) { |
| 218 | DEBUGP("DNAT: Target size %u wrong for %u ranges\n", |
| 219 | targinfosize, mr->rangesize); |
| 220 | return 0; |
| 221 | } |
| 222 | |
| 223 | /* Only allow these for NAT. */ |
| 224 | if (strcmp(tablename, "nat") != 0) { |
| 225 | DEBUGP("DNAT: wrong table %s\n", tablename); |
| 226 | return 0; |
| 227 | } |
| 228 | |
| 229 | if (hook_mask & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT))) { |
| 230 | DEBUGP("DNAT: hook mask 0x%x bad\n", hook_mask); |
| 231 | return 0; |
| 232 | } |
| 233 | |
| 234 | return 1; |
| 235 | } |
| 236 | |
| 237 | inline unsigned int |
| 238 | alloc_null_binding(struct ip_conntrack *conntrack, |
| 239 | struct ip_nat_info *info, |
| 240 | unsigned int hooknum) |
| 241 | { |
| 242 | /* Force range to this IP; let proto decide mapping for |
| 243 | per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). |
| 244 | Use reply in case it's already been mangled (eg local packet). |
| 245 | */ |
| 246 | u_int32_t ip |
| 247 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC |
| 248 | ? conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip |
| 249 | : conntrack->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip); |
| 250 | struct ip_nat_range range |
| 251 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } }; |
| 252 | |
| 253 | DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n", conntrack, |
| 254 | NIPQUAD(ip)); |
| 255 | return ip_nat_setup_info(conntrack, &range, hooknum); |
| 256 | } |
| 257 | |
| 258 | int ip_nat_rule_find(struct sk_buff **pskb, |
| 259 | unsigned int hooknum, |
| 260 | const struct net_device *in, |
| 261 | const struct net_device *out, |
| 262 | struct ip_conntrack *ct, |
| 263 | struct ip_nat_info *info) |
| 264 | { |
| 265 | int ret; |
| 266 | |
| 267 | ret = ipt_do_table(pskb, hooknum, in, out, &nat_table, NULL); |
| 268 | |
| 269 | if (ret == NF_ACCEPT) { |
| 270 | if (!ip_nat_initialized(ct, HOOK2MANIP(hooknum))) |
| 271 | /* NUL mapping */ |
| 272 | ret = alloc_null_binding(ct, info, hooknum); |
| 273 | } |
| 274 | return ret; |
| 275 | } |
| 276 | |
| 277 | static struct ipt_target ipt_snat_reg = { |
| 278 | .name = "SNAT", |
| 279 | .target = ipt_snat_target, |
| 280 | .checkentry = ipt_snat_checkentry, |
| 281 | }; |
| 282 | |
| 283 | static struct ipt_target ipt_dnat_reg = { |
| 284 | .name = "DNAT", |
| 285 | .target = ipt_dnat_target, |
| 286 | .checkentry = ipt_dnat_checkentry, |
| 287 | }; |
| 288 | |
| 289 | int __init ip_nat_rule_init(void) |
| 290 | { |
| 291 | int ret; |
| 292 | |
| 293 | ret = ipt_register_table(&nat_table, &nat_initial_table.repl); |
| 294 | if (ret != 0) |
| 295 | return ret; |
| 296 | ret = ipt_register_target(&ipt_snat_reg); |
| 297 | if (ret != 0) |
| 298 | goto unregister_table; |
| 299 | |
| 300 | ret = ipt_register_target(&ipt_dnat_reg); |
| 301 | if (ret != 0) |
| 302 | goto unregister_snat; |
| 303 | |
| 304 | return ret; |
| 305 | |
| 306 | unregister_snat: |
| 307 | ipt_unregister_target(&ipt_snat_reg); |
| 308 | unregister_table: |
| 309 | ipt_unregister_table(&nat_table); |
| 310 | |
| 311 | return ret; |
| 312 | } |
| 313 | |
| 314 | void ip_nat_rule_cleanup(void) |
| 315 | { |
| 316 | ipt_unregister_target(&ipt_dnat_reg); |
| 317 | ipt_unregister_target(&ipt_snat_reg); |
| 318 | ipt_unregister_table(&nat_table); |
| 319 | } |