net/ipv4/netfilter/nf_conntrack_l3proto_ipv4.c

   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  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   9  *      - move L3 protocol dependent part to this file.
  10  * 23 Mar 2004: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  11  *      - add get_features() to support various size of conntrack
  12  *        structures.
  13  *
  14  * Derived from net/ipv4/netfilter/ip_conntrack_standalone.c
  15  */
  16
  17 #include <linux/types.h>
  18 #include <linux/ip.h>
  19 #include <linux/netfilter.h>
  20 #include <linux/module.h>
  21 #include <linux/skbuff.h>
  22 #include <linux/icmp.h>
  23 #include <linux/sysctl.h>
  24 #include <net/route.h>
  25 #include <net/ip.h>
  26
  27 #include <linux/netfilter_ipv4.h>
  28 #include <net/netfilter/nf_conntrack.h>
  29 #include <net/netfilter/nf_conntrack_helper.h>
  30 #include <net/netfilter/nf_conntrack_l4proto.h>
  31 #include <net/netfilter/nf_conntrack_l3proto.h>
  32 #include <net/netfilter/nf_conntrack_core.h>
  33 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  34
  35 #if 0
  36 #define DEBUGP printk
  37 #else
  38 #define DEBUGP(format, args...)
  39 #endif
  40
  41 static int ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
  42                              struct nf_conntrack_tuple *tuple)
  43 {
  44         __be32 _addrs[2], *ap;
  45         ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
  46                                 sizeof(u_int32_t) * 2, _addrs);
  47         if (ap == NULL)
  48                 return 0;
  49
  50         tuple->src.u3.ip = ap[0];
  51         tuple->dst.u3.ip = ap[1];
  52
  53         return 1;
  54 }
  55
  56 static int ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
  57                            const struct nf_conntrack_tuple *orig)
  58 {
  59         tuple->src.u3.ip = orig->dst.u3.ip;
  60         tuple->dst.u3.ip = orig->src.u3.ip;
  61
  62         return 1;
  63 }
  64
  65 static int ipv4_print_tuple(struct seq_file *s,
  66                             const struct nf_conntrack_tuple *tuple)
  67 {
  68         return seq_printf(s, "src=%u.%u.%u.%u dst=%u.%u.%u.%u ",
  69                           NIPQUAD(tuple->src.u3.ip),
  70                           NIPQUAD(tuple->dst.u3.ip));
  71 }
  72
  73 static int ipv4_print_conntrack(struct seq_file *s,
  74                                 const struct nf_conn *conntrack)
  75 {
  76         return 0;
  77 }
  78
  79 /* Returns new sk_buff, or NULL */
  80 static struct sk_buff *
  81 nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
  82 {
  83         skb_orphan(skb);
  84
  85         local_bh_disable();
  86         skb = ip_defrag(skb, user);
  87         local_bh_enable();
  88
  89         if (skb)
  90                 ip_send_check(skb->nh.iph);
  91
  92         return skb;
  93 }
  94
  95 static int
  96 ipv4_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
  97              u_int8_t *protonum)
  98 {
  99         /* Never happen */
 100         if ((*pskb)->nh.iph->frag_off & htons(IP_OFFSET)) {
 101                 if (net_ratelimit()) {
 102                         printk(KERN_ERR "ipv4_prepare: Frag of proto %u (hook=%u)\n",
 103                         (*pskb)->nh.iph->protocol, hooknum);
 104                 }
 105                 return -NF_DROP;
 106         }
 107
 108         *dataoff = (*pskb)->nh.raw - (*pskb)->data + (*pskb)->nh.iph->ihl*4;
 109         *protonum = (*pskb)->nh.iph->protocol;
 110
 111         return NF_ACCEPT;
 112 }
 113
 114 int nf_nat_module_is_loaded = 0;
 115 EXPORT_SYMBOL_GPL(nf_nat_module_is_loaded);
 116
 117 static u_int32_t ipv4_get_features(const struct nf_conntrack_tuple *tuple)
 118 {
 119         if (nf_nat_module_is_loaded)
 120                 return NF_CT_F_NAT;
 121
 122         return NF_CT_F_BASIC;
 123 }
 124
 125 static unsigned int ipv4_confirm(unsigned int hooknum,
 126                                  struct sk_buff **pskb,
 127                                  const struct net_device *in,
 128                                  const struct net_device *out,
 129                                  int (*okfn)(struct sk_buff *))
 130 {
 131         /* We've seen it coming out the other side: confirm it */
 132         return nf_conntrack_confirm(pskb);
 133 }
 134
 135 static unsigned int ipv4_conntrack_help(unsigned int hooknum,
 136                                       struct sk_buff **pskb,
 137                                       const struct net_device *in,
 138                                       const struct net_device *out,
 139                                       int (*okfn)(struct sk_buff *))
 140 {
 141         struct nf_conn *ct;
 142         enum ip_conntrack_info ctinfo;
 143         struct nf_conn_help *help;
 144
 145         /* This is where we call the helper: as the packet goes out. */
 146         ct = nf_ct_get(*pskb, &ctinfo);
 147         if (!ct || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)
 148                 return NF_ACCEPT;
 149
 150         help = nfct_help(ct);
 151         if (!help || !help->helper)
 152                 return NF_ACCEPT;
 153
 154         return help->helper->help(pskb,
 155                                (*pskb)->nh.raw - (*pskb)->data
 156                                                + (*pskb)->nh.iph->ihl*4,
 157                                ct, ctinfo);
 158 }
 159
 160 static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
 161                                           struct sk_buff **pskb,
 162                                           const struct net_device *in,
 163                                           const struct net_device *out,
 164                                           int (*okfn)(struct sk_buff *))
 165 {
 166 #if !defined(CONFIG_IP_NF_NAT) && !defined(CONFIG_IP_NF_NAT_MODULE)
 167         /* Previously seen (loopback)?  Ignore.  Do this before
 168            fragment check. */
 169         if ((*pskb)->nfct)
 170                 return NF_ACCEPT;
 171 #endif
 172
 173         /* Gather fragments. */
 174         if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
 175                 *pskb = nf_ct_ipv4_gather_frags(*pskb,
 176                                                 hooknum == NF_IP_PRE_ROUTING ?
 177                                                 IP_DEFRAG_CONNTRACK_IN :
 178                                                 IP_DEFRAG_CONNTRACK_OUT);
 179                 if (!*pskb)
 180                         return NF_STOLEN;
 181         }
 182         return NF_ACCEPT;
 183 }
 184
 185 static unsigned int ipv4_conntrack_in(unsigned int hooknum,
 186                                       struct sk_buff **pskb,
 187                                       const struct net_device *in,
 188                                       const struct net_device *out,
 189                                       int (*okfn)(struct sk_buff *))
 190 {
 191         return nf_conntrack_in(PF_INET, hooknum, pskb);
 192 }
 193
 194 static unsigned int ipv4_conntrack_local(unsigned int hooknum,
 195                                          struct sk_buff **pskb,
 196                                          const struct net_device *in,
 197                                          const struct net_device *out,
 198                                          int (*okfn)(struct sk_buff *))
 199 {
 200         /* root is playing with raw sockets. */
 201         if ((*pskb)->len < sizeof(struct iphdr)
 202             || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
 203                 if (net_ratelimit())
 204                         printk("ipt_hook: happy cracking.\n");
 205                 return NF_ACCEPT;
 206         }
 207         return nf_conntrack_in(PF_INET, hooknum, pskb);
 208 }
 209
 210 /* Connection tracking may drop packets, but never alters them, so
 211    make it the first hook. */
 212 static struct nf_hook_ops ipv4_conntrack_ops[] = {
 213         {
 214                 .hook           = ipv4_conntrack_defrag,
 215                 .owner          = THIS_MODULE,
 216                 .pf             = PF_INET,
 217                 .hooknum        = NF_IP_PRE_ROUTING,
 218                 .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
 219         },
 220         {
 221                 .hook           = ipv4_conntrack_in,
 222                 .owner          = THIS_MODULE,
 223                 .pf             = PF_INET,
 224                 .hooknum        = NF_IP_PRE_ROUTING,
 225                 .priority       = NF_IP_PRI_CONNTRACK,
 226         },
 227         {
 228                 .hook           = ipv4_conntrack_defrag,
 229                 .owner          = THIS_MODULE,
 230                 .pf             = PF_INET,
 231                 .hooknum        = NF_IP_LOCAL_OUT,
 232                 .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
 233         },
 234         {
 235                 .hook           = ipv4_conntrack_local,
 236                 .owner          = THIS_MODULE,
 237                 .pf             = PF_INET,
 238                 .hooknum        = NF_IP_LOCAL_OUT,
 239                 .priority       = NF_IP_PRI_CONNTRACK,
 240         },
 241         {
 242                 .hook           = ipv4_conntrack_help,
 243                 .owner          = THIS_MODULE,
 244                 .pf             = PF_INET,
 245                 .hooknum        = NF_IP_POST_ROUTING,
 246                 .priority       = NF_IP_PRI_CONNTRACK_HELPER,
 247         },
 248         {
 249                 .hook           = ipv4_conntrack_help,
 250                 .owner          = THIS_MODULE,
 251                 .pf             = PF_INET,
 252                 .hooknum        = NF_IP_LOCAL_IN,
 253                 .priority       = NF_IP_PRI_CONNTRACK_HELPER,
 254         },
 255         {
 256                 .hook           = ipv4_confirm,
 257                 .owner          = THIS_MODULE,
 258                 .pf             = PF_INET,
 259                 .hooknum        = NF_IP_POST_ROUTING,
 260                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM,
 261         },
 262         {
 263                 .hook           = ipv4_confirm,
 264                 .owner          = THIS_MODULE,
 265                 .pf             = PF_INET,
 266                 .hooknum        = NF_IP_LOCAL_IN,
 267                 .priority       = NF_IP_PRI_CONNTRACK_CONFIRM,
 268         },
 269 };
 270
 271 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 272 static int log_invalid_proto_min = 0;
 273 static int log_invalid_proto_max = 255;
 274
 275 static ctl_table ip_ct_sysctl_table[] = {
 276         {
 277                 .ctl_name       = NET_IPV4_NF_CONNTRACK_MAX,
 278                 .procname       = "ip_conntrack_max",
 279                 .data           = &nf_conntrack_max,
 280                 .maxlen         = sizeof(int),
 281                 .mode           = 0644,
 282                 .proc_handler   = &proc_dointvec,
 283         },
 284         {
 285                 .ctl_name       = NET_IPV4_NF_CONNTRACK_COUNT,
 286                 .procname       = "ip_conntrack_count",
 287                 .data           = &nf_conntrack_count,
 288                 .maxlen         = sizeof(int),
 289                 .mode           = 0444,
 290                 .proc_handler   = &proc_dointvec,
 291         },
 292         {
 293                 .ctl_name       = NET_IPV4_NF_CONNTRACK_BUCKETS,
 294                 .procname       = "ip_conntrack_buckets",
 295                 .data           = &nf_conntrack_htable_size,
 296                 .maxlen         = sizeof(unsigned int),
 297                 .mode           = 0444,
 298                 .proc_handler   = &proc_dointvec,
 299         },
 300         {
 301                 .ctl_name       = NET_IPV4_NF_CONNTRACK_CHECKSUM,
 302                 .procname       = "ip_conntrack_checksum",
 303                 .data           = &nf_conntrack_checksum,
 304                 .maxlen         = sizeof(int),
 305                 .mode           = 0644,
 306                 .proc_handler   = &proc_dointvec,
 307         },
 308         {
 309                 .ctl_name       = NET_IPV4_NF_CONNTRACK_LOG_INVALID,
 310                 .procname       = "ip_conntrack_log_invalid",
 311                 .data           = &nf_ct_log_invalid,
 312                 .maxlen         = sizeof(unsigned int),
 313                 .mode           = 0644,
 314                 .proc_handler   = &proc_dointvec_minmax,
 315                 .strategy       = &sysctl_intvec,
 316                 .extra1         = &log_invalid_proto_min,
 317                 .extra2         = &log_invalid_proto_max,
 318         },
 319         {
 320                 .ctl_name       = 0
 321         }
 322 };
 323 #endif /* CONFIG_SYSCTL && CONFIG_NF_CONNTRACK_PROC_COMPAT */
 324
 325 /* Fast function for those who don't want to parse /proc (and I don't
 326    blame them). */
 327 /* Reversing the socket's dst/src point of view gives us the reply
 328    mapping. */
 329 static int
 330 getorigdst(struct sock *sk, int optval, void __user *user, int *len)
 331 {
 332         struct inet_sock *inet = inet_sk(sk);
 333         struct nf_conntrack_tuple_hash *h;
 334         struct nf_conntrack_tuple tuple;
 335
 336         NF_CT_TUPLE_U_BLANK(&tuple);
 337         tuple.src.u3.ip = inet->rcv_saddr;
 338         tuple.src.u.tcp.port = inet->sport;
 339         tuple.dst.u3.ip = inet->daddr;
 340         tuple.dst.u.tcp.port = inet->dport;
 341         tuple.src.l3num = PF_INET;
 342         tuple.dst.protonum = IPPROTO_TCP;
 343
 344         /* We only do TCP at the moment: is there a better way? */
 345         if (strcmp(sk->sk_prot->name, "TCP")) {
 346                 DEBUGP("SO_ORIGINAL_DST: Not a TCP socket\n");
 347                 return -ENOPROTOOPT;
 348         }
 349
 350         if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
 351                 DEBUGP("SO_ORIGINAL_DST: len %u not %u\n",
 352                        *len, sizeof(struct sockaddr_in));
 353                 return -EINVAL;
 354         }
 355
 356         h = nf_conntrack_find_get(&tuple, NULL);
 357         if (h) {
 358                 struct sockaddr_in sin;
 359                 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
 360
 361                 sin.sin_family = AF_INET;
 362                 sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
 363                         .tuple.dst.u.tcp.port;
 364                 sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
 365                         .tuple.dst.u3.ip;
 366                 memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
 367
 368                 DEBUGP("SO_ORIGINAL_DST: %u.%u.%u.%u %u\n",
 369                        NIPQUAD(sin.sin_addr.s_addr), ntohs(sin.sin_port));
 370                 nf_ct_put(ct);
 371                 if (copy_to_user(user, &sin, sizeof(sin)) != 0)
 372                         return -EFAULT;
 373                 else
 374                         return 0;
 375         }
 376         DEBUGP("SO_ORIGINAL_DST: Can't find %u.%u.%u.%u/%u-%u.%u.%u.%u/%u.\n",
 377                NIPQUAD(tuple.src.u3.ip), ntohs(tuple.src.u.tcp.port),
 378                NIPQUAD(tuple.dst.u3.ip), ntohs(tuple.dst.u.tcp.port));
 379         return -ENOENT;
 380 }
 381
 382 #if defined(CONFIG_NF_CT_NETLINK) || \
 383     defined(CONFIG_NF_CT_NETLINK_MODULE)
 384
 385 #include <linux/netfilter/nfnetlink.h>
 386 #include <linux/netfilter/nfnetlink_conntrack.h>
 387
 388 static int ipv4_tuple_to_nfattr(struct sk_buff *skb,
 389                                 const struct nf_conntrack_tuple *tuple)
 390 {
 391         NFA_PUT(skb, CTA_IP_V4_SRC, sizeof(u_int32_t),
 392                 &tuple->src.u3.ip);
 393         NFA_PUT(skb, CTA_IP_V4_DST, sizeof(u_int32_t),
 394                 &tuple->dst.u3.ip);
 395         return 0;
 396
 397 nfattr_failure:
 398         return -1;
 399 }
 400
 401 static const size_t cta_min_ip[CTA_IP_MAX] = {
 402         [CTA_IP_V4_SRC-1]       = sizeof(u_int32_t),
 403         [CTA_IP_V4_DST-1]       = sizeof(u_int32_t),
 404 };
 405
 406 static int ipv4_nfattr_to_tuple(struct nfattr *tb[],
 407                                 struct nf_conntrack_tuple *t)
 408 {
 409         if (!tb[CTA_IP_V4_SRC-1] || !tb[CTA_IP_V4_DST-1])
 410                 return -EINVAL;
 411
 412         if (nfattr_bad_size(tb, CTA_IP_MAX, cta_min_ip))
 413                 return -EINVAL;
 414
 415         t->src.u3.ip = *(__be32 *)NFA_DATA(tb[CTA_IP_V4_SRC-1]);
 416         t->dst.u3.ip = *(__be32 *)NFA_DATA(tb[CTA_IP_V4_DST-1]);
 417
 418         return 0;
 419 }
 420 #endif
 421
 422 static struct nf_sockopt_ops so_getorigdst = {
 423         .pf             = PF_INET,
 424         .get_optmin     = SO_ORIGINAL_DST,
 425         .get_optmax     = SO_ORIGINAL_DST+1,
 426         .get            = &getorigdst,
 427 };
 428
 429 struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 = {
 430         .l3proto         = PF_INET,
 431         .name            = "ipv4",
 432         .pkt_to_tuple    = ipv4_pkt_to_tuple,
 433         .invert_tuple    = ipv4_invert_tuple,
 434         .print_tuple     = ipv4_print_tuple,
 435         .print_conntrack = ipv4_print_conntrack,
 436         .prepare         = ipv4_prepare,
 437         .get_features    = ipv4_get_features,
 438 #if defined(CONFIG_NF_CT_NETLINK) || \
 439     defined(CONFIG_NF_CT_NETLINK_MODULE)
 440         .tuple_to_nfattr = ipv4_tuple_to_nfattr,
 441         .nfattr_to_tuple = ipv4_nfattr_to_tuple,
 442 #endif
 443 #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 444         .ctl_table_path  = nf_net_ipv4_netfilter_sysctl_path,
 445         .ctl_table       = ip_ct_sysctl_table,
 446 #endif
 447         .me              = THIS_MODULE,
 448 };
 449
 450 MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
 451 MODULE_ALIAS("ip_conntrack");
 452 MODULE_LICENSE("GPL");
 453
 454 static int __init nf_conntrack_l3proto_ipv4_init(void)
 455 {
 456         int ret = 0;
 457
 458         need_conntrack();
 459
 460         ret = nf_register_sockopt(&so_getorigdst);
 461         if (ret < 0) {
 462                 printk(KERN_ERR "Unable to register netfilter socket option\n");
 463                 return ret;
 464         }
 465
 466         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_tcp4);
 467         if (ret < 0) {
 468                 printk("nf_conntrack_ipv4: can't register tcp.\n");
 469                 goto cleanup_sockopt;
 470         }
 471
 472         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udp4);
 473         if (ret < 0) {
 474                 printk("nf_conntrack_ipv4: can't register udp.\n");
 475                 goto cleanup_tcp;
 476         }
 477
 478         ret = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_icmp);
 479         if (ret < 0) {
 480                 printk("nf_conntrack_ipv4: can't register icmp.\n");
 481                 goto cleanup_udp;
 482         }
 483
 484         ret = nf_conntrack_l3proto_register(&nf_conntrack_l3proto_ipv4);
 485         if (ret < 0) {
 486                 printk("nf_conntrack_ipv4: can't register ipv4\n");
 487                 goto cleanup_icmp;
 488         }
 489
 490         ret = nf_register_hooks(ipv4_conntrack_ops,
 491                                 ARRAY_SIZE(ipv4_conntrack_ops));
 492         if (ret < 0) {
 493                 printk("nf_conntrack_ipv4: can't register hooks.\n");
 494                 goto cleanup_ipv4;
 495         }
 496 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 497         ret = nf_conntrack_ipv4_compat_init();
 498         if (ret < 0)
 499                 goto cleanup_hooks;
 500 #endif
 501         return ret;
 502 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 503  cleanup_hooks:
 504         nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
 505 #endif
 506  cleanup_ipv4:
 507         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
 508  cleanup_icmp:
 509         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
 510  cleanup_udp:
 511         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
 512  cleanup_tcp:
 513         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
 514  cleanup_sockopt:
 515         nf_unregister_sockopt(&so_getorigdst);
 516         return ret;
 517 }
 518
 519 static void __exit nf_conntrack_l3proto_ipv4_fini(void)
 520 {
 521         synchronize_net();
 522 #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
 523         nf_conntrack_ipv4_compat_fini();
 524 #endif
 525         nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
 526         nf_conntrack_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
 527         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_icmp);
 528         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udp4);
 529         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
 530         nf_unregister_sockopt(&so_getorigdst);
 531 }
 532
 533 module_init(nf_conntrack_l3proto_ipv4_init);
 534 module_exit(nf_conntrack_l3proto_ipv4_fini);