sys/contrib/ipfilter/netinet/ip_proxy.c

   1 /*
   2  * Copyright (C) 1997-2002 by Darren Reed.
   3  *
   4  * See the IPFILTER.LICENCE file for details on licencing.
   5  */
   6
   7 #if defined(__FreeBSD__) && defined(KERNEL) && !defined(_KERNEL)
   8 # define        _KERNEL
   9 #endif
  10
  11 #ifdef __sgi
  12 # include <sys/ptimers.h>
  13 #endif
  14 #include <sys/errno.h>
  15 #include <sys/types.h>
  16 #include <sys/param.h>
  17 #include <sys/time.h>
  18 #include <sys/file.h>
  19 #if !defined(__FreeBSD_version)
  20 # include <sys/ioctl.h>
  21 #endif
  22 #include <sys/fcntl.h>
  23 #if !defined(_KERNEL) && !defined(KERNEL)
  24 # include <stdio.h>
  25 # include <string.h>
  26 # include <stdlib.h>
  27 #endif
  28 #ifndef linux
  29 # include <sys/protosw.h>
  30 #endif
  31 #include <sys/socket.h>
  32 #if defined(_KERNEL)
  33 # if !defined(linux)
  34 #  include <sys/systm.h>
  35 # else
  36 #  include <linux/string.h>
  37 # endif
  38 #endif
  39 #if !defined(__SVR4) && !defined(__svr4__)
  40 # ifndef linux
  41 #  include <sys/mbuf.h>
  42 # endif
  43 #else
  44 # include <sys/byteorder.h>
  45 # ifdef _KERNEL
  46 #  include <sys/dditypes.h>
  47 # endif
  48 # include <sys/stream.h>
  49 # include <sys/kmem.h>
  50 #endif
  51 #if __FreeBSD__ > 2
  52 # include <sys/queue.h>
  53 #endif
  54 #include <net/if.h>
  55 #ifdef sun
  56 # include <net/af.h>
  57 #endif
  58 #include <net/route.h>
  59 #include <netinet/in.h>
  60 #include <netinet/in_systm.h>
  61 #include <netinet/ip.h>
  62 #ifndef linux
  63 # include <netinet/ip_var.h>
  64 #endif
  65 #include <netinet/tcp.h>
  66 #include <netinet/udp.h>
  67 #include <netinet/ip_icmp.h>
  68 #include "netinet/ip_compat.h"
  69 #include <netinet/tcpip.h>
  70 #include "netinet/ip_fil.h"
  71 #include "netinet/ip_nat.h"
  72 #include "netinet/ip_state.h"
  73 #include "netinet/ip_proxy.h"
  74 #if (__FreeBSD_version >= 300000)
  75 # include <sys/malloc.h>
  76 #endif
  77
  78 #if !defined(lint)
  79 /* static const char rcsid[] = "@(#)$Id: ip_proxy.c,v 2.9.2.6 2001/07/15 22:06:15 darrenr Exp $"; */
  80 static const char rcsid[] = "@(#)$FreeBSD$";
  81 #endif
  82
  83 #if defined(_KERNEL) && (SOLARIS || defined(__sgi))
  84 extern  KRWLOCK_T       ipf_nat, ipf_state;
  85 #endif
  86
  87 #ifndef MIN
  88 #define MIN(a,b)        (((a)<(b))?(a):(b))
  89 #endif
  90
  91 static int appr_fixseqack __P((fr_info_t *, ip_t *, ap_session_t *, int ));
  92
  93
  94 #define AP_SESS_SIZE    53
  95
  96 #include "netinet/ip_ftp_pxy.c"
  97 #if defined(_KERNEL)
  98 #include "netinet/ip_rcmd_pxy.c"
  99 #include "netinet/ip_raudio_pxy.c"
 100 #include "netinet/ip_netbios_pxy.c"
 101 #include "netinet/ip_ipsec_pxy.c"
 102 #endif
 103
 104 ap_session_t    *ap_sess_tab[AP_SESS_SIZE];
 105 ap_session_t    *ap_sess_list = NULL;
 106 aproxy_t        *ap_proxylist = NULL;
 107 aproxy_t        ap_proxies[] = {
 108 #ifdef  IPF_FTP_PROXY
 109         { NULL, "ftp", (char)IPPROTO_TCP, 0, 0, ippr_ftp_init, NULL,
 110           ippr_ftp_new, NULL, ippr_ftp_in, ippr_ftp_out, NULL },
 111 #endif
 112 #ifdef  IPF_RCMD_PROXY
 113         { NULL, "rcmd", (char)IPPROTO_TCP, 0, 0, ippr_rcmd_init, NULL,
 114           ippr_rcmd_new, NULL, NULL, ippr_rcmd_out, NULL },
 115 #endif
 116 #ifdef  IPF_RAUDIO_PROXY
 117         { NULL, "raudio", (char)IPPROTO_TCP, 0, 0, ippr_raudio_init, NULL,
 118           ippr_raudio_new, NULL, ippr_raudio_in, ippr_raudio_out, NULL },
 119 #endif
 120 #ifdef IPF_IPSEC_PROXY
 121         { NULL, "ipsec", (char)IPPROTO_UDP, 0, 0, ippr_ipsec_init, NULL,
 122           ippr_ipsec_new, ippr_ipsec_del, NULL, ippr_ipsec_out,
 123           ippr_ipsec_match },
 124 #endif
 125 #ifdef  IPF_NETBIOS_PROXY
 126         { NULL, "netbios", (char)IPPROTO_UDP, 0, 0, ippr_netbios_init, NULL,
 127           NULL, NULL, NULL, ippr_netbios_out, NULL },
 128 #endif
 129 #ifdef  IPF_H323_PROXY
 130     { NULL, "h323", (char)IPPROTO_TCP, 0, 0, ippr_h323_init, NULL,
 131           ippr_h323_new, ippr_h323_del, ippr_h323_in, ippr_h323_out, NULL },
 132     { NULL, "h245", (char)IPPROTO_TCP, 0, 0, ippr_h245_init, NULL,
 133           ippr_h245_new, NULL, NULL, ippr_h245_out, NULL },
 134 #endif
 135         { NULL, "", '\0', 0, 0, NULL, NULL, NULL }
 136 };
 137
 138
 139 /*
 140  * Dynamically add a new kernel proxy.  Ensure that it is unique in the
 141  * collection compiled in and dynamically added.
 142  */
 143 int appr_add(ap)
 144 aproxy_t *ap;
 145 {
 146         aproxy_t *a;
 147
 148         for (a = ap_proxies; a->apr_p; a++)
 149                 if ((a->apr_p == ap->apr_p) &&
 150                     !strncmp(a->apr_label, ap->apr_label,
 151                              sizeof(ap->apr_label)))
 152                         return -1;
 153
 154         for (a = ap_proxylist; a && a->apr_p; a = a->apr_next)
 155                 if ((a->apr_p == ap->apr_p) &&
 156                     !strncmp(a->apr_label, ap->apr_label,
 157                              sizeof(ap->apr_label)))
 158                         return -1;
 159         ap->apr_next = ap_proxylist;
 160         ap_proxylist = ap;
 161         return (*ap->apr_init)();
 162 }
 163
 164
 165 /*
 166  * Delete a proxy that has been added dynamically from those available.
 167  * If it is in use, return 1 (do not destroy NOW), not in use 0 or -1
 168  * if it cannot be matched.
 169  */
 170 int appr_del(ap)
 171 aproxy_t *ap;
 172 {
 173         aproxy_t *a, **app;
 174
 175         for (app = &ap_proxylist; (a = *app); app = &a->apr_next)
 176                 if (a == ap) {
 177                         a->apr_flags |= APR_DELETE;
 178                         *app = a->apr_next;
 179                         if (ap->apr_ref != 0)
 180                                 return 1;
 181                         return 0;
 182                 }
 183         return -1;
 184 }
 185
 186
 187 /*
 188  * Return 1 if the packet is a good match against a proxy, else 0.
 189  */
 190 int appr_ok(ip, tcp, nat)
 191 ip_t *ip;
 192 tcphdr_t *tcp;
 193 ipnat_t *nat;
 194 {
 195         aproxy_t *apr = nat->in_apr;
 196         u_short dport = nat->in_dport;
 197
 198         if ((apr == NULL) || (apr->apr_flags & APR_DELETE) ||
 199             (ip->ip_p != apr->apr_p))
 200                 return 0;
 201         if (((tcp != NULL) && (tcp->th_dport != dport)) || (!tcp && dport))
 202                 return 0;
 203         return 1;
 204 }
 205
 206
 207 /*
 208  * If a proxy has a match function, call that to do extended packet
 209  * matching.
 210  */
 211 int appr_match(fin, nat)
 212 fr_info_t *fin;
 213 nat_t *nat;
 214 {
 215         aproxy_t *apr;
 216         ipnat_t *ipn;
 217
 218         ipn = nat->nat_ptr;
 219         if (ipn == NULL)
 220                 return -1;
 221         apr = ipn->in_apr;
 222         if ((apr == NULL) || (apr->apr_flags & APR_DELETE) ||
 223             (nat->nat_aps == NULL))
 224                 return -1;
 225         if (apr->apr_match != NULL)
 226                 if ((*apr->apr_match)(fin, nat->nat_aps, nat) != 0)
 227                         return -1;
 228         return 0;
 229 }
 230
 231
 232 /*
 233  * Allocate a new application proxy structure and fill it in with the
 234  * relevant details.  call the init function once complete, prior to
 235  * returning.
 236  */
 237 int appr_new(fin, ip, nat)
 238 fr_info_t *fin;
 239 ip_t *ip;
 240 nat_t *nat;
 241 {
 242         register ap_session_t *aps;
 243         aproxy_t *apr;
 244
 245         if ((nat->nat_ptr == NULL) || (nat->nat_aps != NULL))
 246                 return -1;
 247
 248         apr = nat->nat_ptr->in_apr;
 249
 250         if (!apr || (apr->apr_flags & APR_DELETE) || (ip->ip_p != apr->apr_p))
 251                 return -1;
 252
 253         KMALLOC(aps, ap_session_t *);
 254         if (!aps)
 255                 return -1;
 256         bzero((char *)aps, sizeof(*aps));
 257         aps->aps_p = ip->ip_p;
 258         aps->aps_data = NULL;
 259         aps->aps_apr = apr;
 260         aps->aps_psiz = 0;
 261         if (apr->apr_new != NULL)
 262                 if ((*apr->apr_new)(fin, ip, aps, nat) == -1) {
 263                         if ((aps->aps_data != NULL) && (aps->aps_psiz != 0)) {
 264                                 KFREES(aps->aps_data, aps->aps_psiz);
 265                         }
 266                         KFREE(aps);
 267                         return -1;
 268                 }
 269         aps->aps_nat = nat;
 270         aps->aps_next = ap_sess_list;
 271         ap_sess_list = aps;
 272         nat->nat_aps = aps;
 273
 274         return 0;
 275 }
 276
 277
 278 /*
 279  * check to see if a packet should be passed through an active proxy routine
 280  * if one has been setup for it.
 281  */
 282 int appr_check(ip, fin, nat)
 283 ip_t *ip;
 284 fr_info_t *fin;
 285 nat_t *nat;
 286 {
 287 #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
 288         mb_t *m = fin->fin_qfm;
 289         int dosum = 1;
 290 #endif
 291         tcphdr_t *tcp = NULL;
 292         ap_session_t *aps;
 293         aproxy_t *apr;
 294         u_32_t sum;
 295         short rv;
 296         int err;
 297
 298         aps = nat->nat_aps;
 299         if ((aps != NULL) && (aps->aps_p == ip->ip_p)) {
 300                 if (ip->ip_p == IPPROTO_TCP) {
 301                         tcp = (tcphdr_t *)fin->fin_dp;
 302                         /*
 303                          * verify that the checksum is correct.  If not, then
 304                          * don't do anything with this packet.
 305                          */
 306 #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
 307                         if (dohwcksum && (m->b_ick_flag == ICK_VALID)) {
 308                                 sum = tcp->th_sum;
 309                                 dosum = 0;
 310                         }
 311                         if (dosum)
 312                                 sum = fr_tcpsum(fin->fin_qfm, ip, tcp);
 313 #else
 314                         sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip, tcp);
 315 #endif
 316                         if (sum != tcp->th_sum) {
 317                                 frstats[fin->fin_out].fr_tcpbad++;
 318                                 return -1;
 319                         }
 320                 }
 321
 322                 apr = aps->aps_apr;
 323                 err = 0;
 324                 if (fin->fin_out != 0) {
 325                         if (apr->apr_outpkt != NULL)
 326                                 err = (*apr->apr_outpkt)(fin, ip, aps, nat);
 327                 } else {
 328                         if (apr->apr_inpkt != NULL)
 329                                 err = (*apr->apr_inpkt)(fin, ip, aps, nat);
 330                 }
 331
 332                 rv = APR_EXIT(err);
 333                 if (rv == 1)
 334                         return -1;
 335                 if (rv == 2) {
 336                         appr_free(apr);
 337                         nat->nat_aps = NULL;
 338                         return -1;
 339                 }
 340
 341                 if (tcp != NULL) {
 342                         err = appr_fixseqack(fin, ip, aps, APR_INC(err));
 343 #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6)
 344                         if (dosum)
 345                                 tcp->th_sum = fr_tcpsum(fin->fin_qfm, ip, tcp);
 346 #else
 347                         tcp->th_sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip, tcp);
 348 #endif
 349                 }
 350                 aps->aps_bytes += ip->ip_len;
 351                 aps->aps_pkts++;
 352                 return 1;
 353         }
 354         return 0;
 355 }
 356
 357
 358 /*
 359  * Search for an proxy by the protocol it is being used with and its name.
 360  */
 361 aproxy_t *appr_lookup(pr, name)
 362 u_int pr;
 363 char *name;
 364 {
 365         aproxy_t *ap;
 366
 367         for (ap = ap_proxies; ap->apr_p; ap++)
 368                 if ((ap->apr_p == pr) &&
 369                     !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
 370                         ap->apr_ref++;
 371                         return ap;
 372                 }
 373
 374         for (ap = ap_proxylist; ap; ap = ap->apr_next)
 375                 if ((ap->apr_p == pr) &&
 376                     !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) {
 377                         ap->apr_ref++;
 378                         return ap;
 379                 }
 380         return NULL;
 381 }
 382
 383
 384 void appr_free(ap)
 385 aproxy_t *ap;
 386 {
 387         ap->apr_ref--;
 388 }
 389
 390
 391 void aps_free(aps)
 392 ap_session_t *aps;
 393 {
 394         ap_session_t *a, **ap;
 395         aproxy_t *apr;
 396
 397         if (!aps)
 398                 return;
 399
 400         for (ap = &ap_sess_list; (a = *ap); ap = &a->aps_next)
 401                 if (a == aps) {
 402                         *ap = a->aps_next;
 403                         break;
 404                 }
 405
 406         apr = aps->aps_apr;
 407         if ((apr != NULL) && (apr->apr_del != NULL))
 408                 (*apr->apr_del)(aps);
 409
 410         if ((aps->aps_data != NULL) && (aps->aps_psiz != 0))
 411                 KFREES(aps->aps_data, aps->aps_psiz);
 412         KFREE(aps);
 413 }
 414
 415
 416 static int appr_fixseqack(fin, ip, aps, inc)
 417 fr_info_t *fin;
 418 ip_t *ip;
 419 ap_session_t *aps;
 420 int inc;
 421 {
 422         int sel, ch = 0, out, nlen;
 423         u_32_t seq1, seq2;
 424         tcphdr_t *tcp;
 425         short inc2;
 426
 427         tcp = (tcphdr_t *)fin->fin_dp;
 428         out = fin->fin_out;
 429         nlen = ip->ip_len;
 430         nlen -= (ip->ip_hl << 2) + (tcp->th_off << 2);
 431         inc2 = inc;
 432         inc = (int)inc2;
 433
 434         if (out != 0) {
 435                 seq1 = (u_32_t)ntohl(tcp->th_seq);
 436                 sel = aps->aps_sel[out];
 437
 438                 /* switch to other set ? */
 439                 if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
 440                     (seq1 > aps->aps_seqmin[!sel]))
 441                         sel = aps->aps_sel[out] = !sel;
 442
 443                 if (aps->aps_seqoff[sel]) {
 444                         seq2 = aps->aps_seqmin[sel] - aps->aps_seqoff[sel];
 445                         if (seq1 > seq2) {
 446                                 seq2 = aps->aps_seqoff[sel];
 447                                 seq1 += seq2;
 448                                 tcp->th_seq = htonl(seq1);
 449                                 ch = 1;
 450                         }
 451                 }
 452
 453                 if (inc && (seq1 > aps->aps_seqmin[!sel])) {
 454                         aps->aps_seqmin[!sel] = seq1 + nlen - 1;
 455                         aps->aps_seqoff[!sel] = aps->aps_seqoff[sel] + inc;
 456                 }
 457
 458                 /***/
 459
 460                 seq1 = ntohl(tcp->th_ack);
 461                 sel = aps->aps_sel[1 - out];
 462
 463                 /* switch to other set ? */
 464                 if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
 465                     (seq1 > aps->aps_ackmin[!sel]))
 466                         sel = aps->aps_sel[1 - out] = !sel;
 467
 468                 if (aps->aps_ackoff[sel] && (seq1 > aps->aps_ackmin[sel])) {
 469                         seq2 = aps->aps_ackoff[sel];
 470                         tcp->th_ack = htonl(seq1 - seq2);
 471                         ch = 1;
 472                 }
 473         } else {
 474                 seq1 = ntohl(tcp->th_seq);
 475                 sel = aps->aps_sel[out];
 476
 477                 /* switch to other set ? */
 478                 if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) &&
 479                     (seq1 > aps->aps_ackmin[!sel]))
 480                         sel = aps->aps_sel[out] = !sel;
 481
 482                 if (aps->aps_ackoff[sel]) {
 483                         seq2 = aps->aps_ackmin[sel] -
 484                                aps->aps_ackoff[sel];
 485                         if (seq1 > seq2) {
 486                                 seq2 = aps->aps_ackoff[sel];
 487                                 seq1 += seq2;
 488                                 tcp->th_seq = htonl(seq1);
 489                                 ch = 1;
 490                         }
 491                 }
 492
 493                 if (inc && (seq1 > aps->aps_ackmin[!sel])) {
 494                         aps->aps_ackmin[!sel] = seq1 + nlen - 1;
 495                         aps->aps_ackoff[!sel] = aps->aps_ackoff[sel] + inc;
 496                 }
 497
 498                 /***/
 499
 500                 seq1 = ntohl(tcp->th_ack);
 501                 sel = aps->aps_sel[1 - out];
 502
 503                 /* switch to other set ? */
 504                 if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) &&
 505                     (seq1 > aps->aps_seqmin[!sel]))
 506                         sel = aps->aps_sel[1 - out] = !sel;
 507
 508                 if (aps->aps_seqoff[sel] && (seq1 > aps->aps_seqmin[sel])) {
 509                         seq2 = aps->aps_seqoff[sel];
 510                         tcp->th_ack = htonl(seq1 - seq2);
 511                         ch = 1;
 512                 }
 513         }
 514         return ch ? 2 : 0;
 515 }
 516
 517
 518 /*
 519  * Initialise hook for kernel application proxies.
 520  * Call the initialise routine for all the compiled in kernel proxies.
 521  */
 522 int appr_init()
 523 {
 524         aproxy_t *ap;
 525         int err = 0;
 526
 527         for (ap = ap_proxies; ap->apr_p; ap++) {
 528                 err = (*ap->apr_init)();
 529                 if (err != 0)
 530                         break;
 531         }
 532         return err;
 533 }
 534
 535
 536 /*
 537  * Unload hook for kernel application proxies.
 538  * Call the finialise routine for all the compiled in kernel proxies.
 539  */
 540 void appr_unload()
 541 {
 542         aproxy_t *ap;
 543
 544         for (ap = ap_proxies; ap->apr_p; ap++)
 545                 if (ap->apr_fini)
 546                         (*ap->apr_fini)();
 547         for (ap = ap_proxylist; ap; ap = ap->apr_next)
 548                 if (ap->apr_fini)
 549                         (*ap->apr_fini)();
 550 }