Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 1 | /* (C) 1999-2001 Paul `Rusty' Russell |
| 2 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> |
| 3 | * (C) 2011 Patrick McHardy <kaber@trash.net> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License version 2 as |
| 7 | * published by the Free Software Foundation. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/netfilter.h> |
| 12 | #include <linux/netfilter_ipv4.h> |
| 13 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 14 | #include <linux/ip.h> |
| 15 | #include <net/ip.h> |
| 16 | |
| 17 | #include <net/netfilter/nf_nat.h> |
| 18 | #include <net/netfilter/nf_nat_core.h> |
| 19 | #include <net/netfilter/nf_nat_l3proto.h> |
| 20 | |
| 21 | static const struct xt_table nf_nat_ipv4_table = { |
| 22 | .name = "nat", |
| 23 | .valid_hooks = (1 << NF_INET_PRE_ROUTING) | |
| 24 | (1 << NF_INET_POST_ROUTING) | |
| 25 | (1 << NF_INET_LOCAL_OUT) | |
| 26 | (1 << NF_INET_LOCAL_IN), |
| 27 | .me = THIS_MODULE, |
| 28 | .af = NFPROTO_IPV4, |
| 29 | }; |
| 30 | |
| 31 | static unsigned int alloc_null_binding(struct nf_conn *ct, unsigned int hooknum) |
| 32 | { |
| 33 | /* Force range to this IP; let proto decide mapping for |
| 34 | * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). |
| 35 | */ |
| 36 | struct nf_nat_range range; |
| 37 | |
| 38 | range.flags = 0; |
| 39 | pr_debug("Allocating NULL binding for %p (%pI4)\n", ct, |
| 40 | HOOK2MANIP(hooknum) == NF_NAT_MANIP_SRC ? |
| 41 | &ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip : |
| 42 | &ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); |
| 43 | |
| 44 | return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum)); |
| 45 | } |
| 46 | |
| 47 | static unsigned int nf_nat_rule_find(struct sk_buff *skb, unsigned int hooknum, |
| 48 | const struct net_device *in, |
| 49 | const struct net_device *out, |
| 50 | struct nf_conn *ct) |
| 51 | { |
| 52 | struct net *net = nf_ct_net(ct); |
| 53 | unsigned int ret; |
| 54 | |
| 55 | ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table); |
| 56 | if (ret == NF_ACCEPT) { |
| 57 | if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum))) |
| 58 | ret = alloc_null_binding(ct, hooknum); |
| 59 | } |
| 60 | return ret; |
| 61 | } |
| 62 | |
| 63 | static unsigned int |
| 64 | nf_nat_ipv4_fn(unsigned int hooknum, |
| 65 | struct sk_buff *skb, |
| 66 | const struct net_device *in, |
| 67 | const struct net_device *out, |
| 68 | int (*okfn)(struct sk_buff *)) |
| 69 | { |
| 70 | struct nf_conn *ct; |
| 71 | enum ip_conntrack_info ctinfo; |
| 72 | struct nf_conn_nat *nat; |
| 73 | /* maniptype == SRC for postrouting. */ |
| 74 | enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum); |
| 75 | |
| 76 | /* We never see fragments: conntrack defrags on pre-routing |
| 77 | * and local-out, and nf_nat_out protects post-routing. |
| 78 | */ |
| 79 | NF_CT_ASSERT(!ip_is_fragment(ip_hdr(skb))); |
| 80 | |
| 81 | ct = nf_ct_get(skb, &ctinfo); |
| 82 | /* Can't track? It's not due to stress, or conntrack would |
| 83 | * have dropped it. Hence it's the user's responsibilty to |
| 84 | * packet filter it out, or implement conntrack/NAT for that |
| 85 | * protocol. 8) --RR |
| 86 | */ |
| 87 | if (!ct) |
| 88 | return NF_ACCEPT; |
| 89 | |
| 90 | /* Don't try to NAT if this packet is not conntracked */ |
| 91 | if (nf_ct_is_untracked(ct)) |
| 92 | return NF_ACCEPT; |
| 93 | |
| 94 | nat = nfct_nat(ct); |
| 95 | if (!nat) { |
| 96 | /* NAT module was loaded late. */ |
| 97 | if (nf_ct_is_confirmed(ct)) |
| 98 | return NF_ACCEPT; |
| 99 | nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC); |
| 100 | if (nat == NULL) { |
| 101 | pr_debug("failed to add NAT extension\n"); |
| 102 | return NF_ACCEPT; |
| 103 | } |
| 104 | } |
| 105 | |
| 106 | switch (ctinfo) { |
| 107 | case IP_CT_RELATED: |
| 108 | case IP_CT_RELATED_REPLY: |
| 109 | if (ip_hdr(skb)->protocol == IPPROTO_ICMP) { |
| 110 | if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo, |
| 111 | hooknum)) |
| 112 | return NF_DROP; |
| 113 | else |
| 114 | return NF_ACCEPT; |
| 115 | } |
| 116 | /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */ |
| 117 | case IP_CT_NEW: |
| 118 | /* Seen it before? This can happen for loopback, retrans, |
| 119 | * or local packets. |
| 120 | */ |
| 121 | if (!nf_nat_initialized(ct, maniptype)) { |
| 122 | unsigned int ret; |
| 123 | |
| 124 | ret = nf_nat_rule_find(skb, hooknum, in, out, ct); |
| 125 | if (ret != NF_ACCEPT) |
| 126 | return ret; |
Andrew Collins | c65ef8d | 2012-12-12 14:23:49 +0000 | [diff] [blame] | 127 | } else { |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 128 | pr_debug("Already setup manip %s for ct %p\n", |
| 129 | maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST", |
| 130 | ct); |
Andrew Collins | c65ef8d | 2012-12-12 14:23:49 +0000 | [diff] [blame] | 131 | if (nf_nat_oif_changed(hooknum, ctinfo, nat, out)) |
| 132 | goto oif_changed; |
| 133 | } |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 134 | break; |
| 135 | |
| 136 | default: |
| 137 | /* ESTABLISHED */ |
| 138 | NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED || |
| 139 | ctinfo == IP_CT_ESTABLISHED_REPLY); |
Andrew Collins | c65ef8d | 2012-12-12 14:23:49 +0000 | [diff] [blame] | 140 | if (nf_nat_oif_changed(hooknum, ctinfo, nat, out)) |
| 141 | goto oif_changed; |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 142 | } |
| 143 | |
| 144 | return nf_nat_packet(ct, ctinfo, hooknum, skb); |
Andrew Collins | c65ef8d | 2012-12-12 14:23:49 +0000 | [diff] [blame] | 145 | |
| 146 | oif_changed: |
| 147 | nf_ct_kill_acct(ct, ctinfo, skb); |
| 148 | return NF_DROP; |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 149 | } |
| 150 | |
| 151 | static unsigned int |
| 152 | nf_nat_ipv4_in(unsigned int hooknum, |
| 153 | struct sk_buff *skb, |
| 154 | const struct net_device *in, |
| 155 | const struct net_device *out, |
| 156 | int (*okfn)(struct sk_buff *)) |
| 157 | { |
| 158 | unsigned int ret; |
| 159 | __be32 daddr = ip_hdr(skb)->daddr; |
| 160 | |
| 161 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
| 162 | if (ret != NF_DROP && ret != NF_STOLEN && |
| 163 | daddr != ip_hdr(skb)->daddr) |
| 164 | skb_dst_drop(skb); |
| 165 | |
| 166 | return ret; |
| 167 | } |
| 168 | |
| 169 | static unsigned int |
| 170 | nf_nat_ipv4_out(unsigned int hooknum, |
| 171 | struct sk_buff *skb, |
| 172 | const struct net_device *in, |
| 173 | const struct net_device *out, |
| 174 | int (*okfn)(struct sk_buff *)) |
| 175 | { |
| 176 | #ifdef CONFIG_XFRM |
| 177 | const struct nf_conn *ct; |
| 178 | enum ip_conntrack_info ctinfo; |
Patrick McHardy | aaa795a | 2013-04-05 06:41:12 +0000 | [diff] [blame] | 179 | int err; |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 180 | #endif |
| 181 | unsigned int ret; |
| 182 | |
| 183 | /* root is playing with raw sockets. */ |
| 184 | if (skb->len < sizeof(struct iphdr) || |
| 185 | ip_hdrlen(skb) < sizeof(struct iphdr)) |
| 186 | return NF_ACCEPT; |
| 187 | |
| 188 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
| 189 | #ifdef CONFIG_XFRM |
| 190 | if (ret != NF_DROP && ret != NF_STOLEN && |
| 191 | !(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
| 192 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
| 193 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| 194 | |
| 195 | if ((ct->tuplehash[dir].tuple.src.u3.ip != |
| 196 | ct->tuplehash[!dir].tuple.dst.u3.ip) || |
Ulrich Weber | 38fe36a | 2012-10-25 05:34:45 +0000 | [diff] [blame] | 197 | (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP && |
| 198 | ct->tuplehash[dir].tuple.src.u.all != |
Patrick McHardy | aaa795a | 2013-04-05 06:41:12 +0000 | [diff] [blame] | 199 | ct->tuplehash[!dir].tuple.dst.u.all)) { |
| 200 | err = nf_xfrm_me_harder(skb, AF_INET); |
| 201 | if (err < 0) |
| 202 | ret = NF_DROP_ERR(err); |
| 203 | } |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 204 | } |
| 205 | #endif |
| 206 | return ret; |
| 207 | } |
| 208 | |
| 209 | static unsigned int |
| 210 | nf_nat_ipv4_local_fn(unsigned int hooknum, |
| 211 | struct sk_buff *skb, |
| 212 | const struct net_device *in, |
| 213 | const struct net_device *out, |
| 214 | int (*okfn)(struct sk_buff *)) |
| 215 | { |
| 216 | const struct nf_conn *ct; |
| 217 | enum ip_conntrack_info ctinfo; |
| 218 | unsigned int ret; |
Patrick McHardy | c9e1673 | 2013-04-05 06:41:10 +0000 | [diff] [blame] | 219 | int err; |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 220 | |
| 221 | /* root is playing with raw sockets. */ |
| 222 | if (skb->len < sizeof(struct iphdr) || |
| 223 | ip_hdrlen(skb) < sizeof(struct iphdr)) |
| 224 | return NF_ACCEPT; |
| 225 | |
| 226 | ret = nf_nat_ipv4_fn(hooknum, skb, in, out, okfn); |
| 227 | if (ret != NF_DROP && ret != NF_STOLEN && |
| 228 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
| 229 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
| 230 | |
| 231 | if (ct->tuplehash[dir].tuple.dst.u3.ip != |
| 232 | ct->tuplehash[!dir].tuple.src.u3.ip) { |
Patrick McHardy | c9e1673 | 2013-04-05 06:41:10 +0000 | [diff] [blame] | 233 | err = ip_route_me_harder(skb, RTN_UNSPEC); |
| 234 | if (err < 0) |
| 235 | ret = NF_DROP_ERR(err); |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 236 | } |
| 237 | #ifdef CONFIG_XFRM |
| 238 | else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) && |
Ulrich Weber | 38fe36a | 2012-10-25 05:34:45 +0000 | [diff] [blame] | 239 | ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP && |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 240 | ct->tuplehash[dir].tuple.dst.u.all != |
Patrick McHardy | aaa795a | 2013-04-05 06:41:12 +0000 | [diff] [blame] | 241 | ct->tuplehash[!dir].tuple.src.u.all) { |
| 242 | err = nf_xfrm_me_harder(skb, AF_INET); |
| 243 | if (err < 0) |
| 244 | ret = NF_DROP_ERR(err); |
| 245 | } |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 246 | #endif |
| 247 | } |
| 248 | return ret; |
| 249 | } |
| 250 | |
| 251 | static struct nf_hook_ops nf_nat_ipv4_ops[] __read_mostly = { |
| 252 | /* Before packet filtering, change destination */ |
| 253 | { |
| 254 | .hook = nf_nat_ipv4_in, |
| 255 | .owner = THIS_MODULE, |
| 256 | .pf = NFPROTO_IPV4, |
| 257 | .hooknum = NF_INET_PRE_ROUTING, |
| 258 | .priority = NF_IP_PRI_NAT_DST, |
| 259 | }, |
| 260 | /* After packet filtering, change source */ |
| 261 | { |
| 262 | .hook = nf_nat_ipv4_out, |
| 263 | .owner = THIS_MODULE, |
| 264 | .pf = NFPROTO_IPV4, |
| 265 | .hooknum = NF_INET_POST_ROUTING, |
| 266 | .priority = NF_IP_PRI_NAT_SRC, |
| 267 | }, |
| 268 | /* Before packet filtering, change destination */ |
| 269 | { |
| 270 | .hook = nf_nat_ipv4_local_fn, |
| 271 | .owner = THIS_MODULE, |
| 272 | .pf = NFPROTO_IPV4, |
| 273 | .hooknum = NF_INET_LOCAL_OUT, |
| 274 | .priority = NF_IP_PRI_NAT_DST, |
| 275 | }, |
| 276 | /* After packet filtering, change source */ |
| 277 | { |
| 278 | .hook = nf_nat_ipv4_fn, |
| 279 | .owner = THIS_MODULE, |
| 280 | .pf = NFPROTO_IPV4, |
| 281 | .hooknum = NF_INET_LOCAL_IN, |
| 282 | .priority = NF_IP_PRI_NAT_SRC, |
| 283 | }, |
| 284 | }; |
| 285 | |
| 286 | static int __net_init iptable_nat_net_init(struct net *net) |
| 287 | { |
| 288 | struct ipt_replace *repl; |
| 289 | |
| 290 | repl = ipt_alloc_initial_table(&nf_nat_ipv4_table); |
| 291 | if (repl == NULL) |
| 292 | return -ENOMEM; |
| 293 | net->ipv4.nat_table = ipt_register_table(net, &nf_nat_ipv4_table, repl); |
| 294 | kfree(repl); |
Rusty Russell | 8c6ffba | 2013-07-15 11:20:32 +0930 | [diff] [blame] | 295 | return PTR_ERR_OR_ZERO(net->ipv4.nat_table); |
Patrick McHardy | c7232c9 | 2012-08-26 19:14:06 +0200 | [diff] [blame] | 296 | } |
| 297 | |
| 298 | static void __net_exit iptable_nat_net_exit(struct net *net) |
| 299 | { |
| 300 | ipt_unregister_table(net, net->ipv4.nat_table); |
| 301 | } |
| 302 | |
| 303 | static struct pernet_operations iptable_nat_net_ops = { |
| 304 | .init = iptable_nat_net_init, |
| 305 | .exit = iptable_nat_net_exit, |
| 306 | }; |
| 307 | |
| 308 | static int __init iptable_nat_init(void) |
| 309 | { |
| 310 | int err; |
| 311 | |
| 312 | err = register_pernet_subsys(&iptable_nat_net_ops); |
| 313 | if (err < 0) |
| 314 | goto err1; |
| 315 | |
| 316 | err = nf_register_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops)); |
| 317 | if (err < 0) |
| 318 | goto err2; |
| 319 | return 0; |
| 320 | |
| 321 | err2: |
| 322 | unregister_pernet_subsys(&iptable_nat_net_ops); |
| 323 | err1: |
| 324 | return err; |
| 325 | } |
| 326 | |
| 327 | static void __exit iptable_nat_exit(void) |
| 328 | { |
| 329 | nf_unregister_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops)); |
| 330 | unregister_pernet_subsys(&iptable_nat_net_ops); |
| 331 | } |
| 332 | |
| 333 | module_init(iptable_nat_init); |
| 334 | module_exit(iptable_nat_exit); |
| 335 | |
| 336 | MODULE_LICENSE("GPL"); |