pf_osfp.c revision 1.4
1 /* $NetBSD: pf_osfp.c,v 1.4 2004/11/14 11:12:16 yamt Exp $ */ 2 /* $OpenBSD: pf_osfp.c,v 1.10 2004/04/09 19:30:41 frantzen Exp $ */ 3 4 /* 5 * Copyright (c) 2003 Mike Frantzen <frantzen (at) w4g.org> 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 18 * 19 */ 20 21 #ifdef _KERNEL_OPT 22 #include "opt_inet.h" 23 #endif 24 25 #include <sys/param.h> 26 #include <sys/socket.h> 27 #ifdef _KERNEL 28 # include <sys/systm.h> 29 #endif /* _KERNEL */ 30 #include <sys/mbuf.h> 31 32 #include <netinet/in.h> 33 #include <netinet/in_systm.h> 34 #include <netinet/ip.h> 35 #include <netinet/tcp.h> 36 37 #include <net/if.h> 38 #include <net/pfvar.h> 39 40 #ifdef INET6 41 #include <netinet/ip6.h> 42 #endif /* INET6 */ 43 44 45 #ifdef _KERNEL 46 # define DPFPRINTF(format, x...) \ 47 if (pf_status.debug >= PF_DEBUG_NOISY) \ 48 printf(format , ##x) 49 typedef struct pool pool_t; 50 51 #else 52 /* Userland equivalents so we can lend code to tcpdump et al. */ 53 54 # include <arpa/inet.h> 55 # include <errno.h> 56 # include <stdio.h> 57 # include <stdlib.h> 58 # include <string.h> 59 # define pool_t int 60 # define pool_get(pool, flags) malloc(*(pool)) 61 # define pool_put(pool, item) free(item) 62 # define pool_init(pool, size, a, ao, f, m, p) (*(pool)) = (size) 63 64 # ifdef PFDEBUG 65 # include <sys/stdarg.h> 66 # define DPFPRINTF(format, x...) fprintf(stderr, format , ##x) 67 # else 68 # define DPFPRINTF(format, x...) ((void)0) 69 # endif /* PFDEBUG */ 70 #endif /* _KERNEL */ 71 72 73 SLIST_HEAD(pf_osfp_list, pf_os_fingerprint) pf_osfp_list; 74 pool_t pf_osfp_entry_pl; 75 pool_t pf_osfp_pl; 76 77 struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *, 78 struct pf_os_fingerprint *, u_int8_t); 79 struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *, 80 struct pf_os_fingerprint *); 81 void pf_osfp_insert(struct pf_osfp_list *, 82 struct pf_os_fingerprint *); 83 84 85 #ifdef _KERNEL 86 /* 87 * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only) 88 * Returns the list of possible OSes. 89 */ 90 struct pf_osfp_enlist * 91 pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off, 92 const struct tcphdr *tcp) 93 { 94 struct ip *ip; 95 char hdr[60]; 96 97 /* XXX don't have a fingerprint database for IPv6 :-( */ 98 if (pd->af != PF_INET || pd->proto != IPPROTO_TCP || (tcp->th_off << 2) 99 < sizeof(*tcp)) 100 return (NULL); 101 102 ip = mtod(m, struct ip *); 103 if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL, pd->af)) 104 return (NULL); 105 106 return (pf_osfp_fingerprint_hdr(ip, (struct tcphdr *)hdr)); 107 } 108 #endif /* _KERNEL */ 109 110 struct pf_osfp_enlist * 111 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct tcphdr *tcp) 112 { 113 struct pf_os_fingerprint fp, *fpresult; 114 int cnt, optlen = 0; 115 const u_int8_t *optp; 116 117 if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN || (ip->ip_off & 118 htons(IP_OFFMASK))) 119 return (NULL); 120 121 memset(&fp, 0, sizeof(fp)); 122 123 fp.fp_psize = ntohs(ip->ip_len); 124 fp.fp_ttl = ip->ip_ttl; 125 if (ip->ip_off & htons(IP_DF)) 126 fp.fp_flags |= PF_OSFP_DF; 127 fp.fp_wsize = ntohs(tcp->th_win); 128 129 130 cnt = (tcp->th_off << 2) - sizeof(*tcp); 131 optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp)); 132 for (; cnt > 0; cnt -= optlen, optp += optlen) { 133 if (*optp == TCPOPT_EOL) 134 break; 135 136 fp.fp_optcnt++; 137 if (*optp == TCPOPT_NOP) { 138 fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) | 139 PF_OSFP_TCPOPT_NOP; 140 optlen = 1; 141 } else { 142 if (cnt < 2) 143 return (NULL); 144 optlen = optp[1]; 145 if (optlen > cnt || optlen < 2) 146 return (NULL); 147 switch (*optp) { 148 case TCPOPT_MAXSEG: 149 if (optlen >= TCPOLEN_MAXSEG) 150 memcpy(&fp.fp_mss, &optp[2], 151 sizeof(fp.fp_mss)); 152 fp.fp_tcpopts = (fp.fp_tcpopts << 153 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS; 154 NTOHS(fp.fp_mss); 155 break; 156 case TCPOPT_WINDOW: 157 if (optlen >= TCPOLEN_WINDOW) 158 memcpy(&fp.fp_wscale, &optp[2], 159 sizeof(fp.fp_wscale)); 160 NTOHS(fp.fp_wscale); 161 fp.fp_tcpopts = (fp.fp_tcpopts << 162 PF_OSFP_TCPOPT_BITS) | 163 PF_OSFP_TCPOPT_WSCALE; 164 break; 165 case TCPOPT_SACK_PERMITTED: 166 fp.fp_tcpopts = (fp.fp_tcpopts << 167 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK; 168 break; 169 case TCPOPT_TIMESTAMP: 170 if (optlen >= TCPOLEN_TIMESTAMP) { 171 u_int32_t ts; 172 memcpy(&ts, &optp[2], sizeof(ts)); 173 if (ts == 0) 174 fp.fp_flags |= PF_OSFP_TS0; 175 176 } 177 fp.fp_tcpopts = (fp.fp_tcpopts << 178 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS; 179 break; 180 default: 181 return (NULL); 182 } 183 } 184 optlen = MAX(optlen, 1); /* paranoia */ 185 } 186 187 DPFPRINTF("fingerprinted %s:%d %d:%d:%d:%d:%llx (%d) " 188 "(TS=%s,M=%s%d,W=%s%d)\n", 189 inet_ntoa(ip->ip_src), ntohs(tcp->th_sport), 190 fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0, 191 fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt, 192 (fp.fp_flags & PF_OSFP_TS0) ? "0" : "", 193 (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" : 194 (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "", 195 fp.fp_mss, 196 (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" : 197 (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "", 198 fp.fp_wscale); 199 200 if ((fpresult = pf_osfp_find(&pf_osfp_list, &fp, 201 PF_OSFP_MAXTTL_OFFSET))) 202 return (&fpresult->fp_oses); 203 return (NULL); 204 } 205 206 /* Match a fingerprint ID against a list of OSes */ 207 int 208 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os) 209 { 210 struct pf_osfp_entry *entry; 211 int os_class, os_version, os_subtype; 212 int en_class, en_version, en_subtype; 213 214 if (os == PF_OSFP_ANY) 215 return (1); 216 if (list == NULL) { 217 DPFPRINTF("osfp no match against %x\n", os); 218 return (os == PF_OSFP_UNKNOWN); 219 } 220 PF_OSFP_UNPACK(os, os_class, os_version, os_subtype); 221 SLIST_FOREACH(entry, list, fp_entry) { 222 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype); 223 if ((os_class == PF_OSFP_ANY || en_class == os_class) && 224 (os_version == PF_OSFP_ANY || en_version == os_version) && 225 (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) { 226 DPFPRINTF("osfp matched %s %s %s %x==%x\n", 227 entry->fp_class_nm, entry->fp_version_nm, 228 entry->fp_subtype_nm, os, entry->fp_os); 229 return (1); 230 } 231 } 232 DPFPRINTF("fingerprint 0x%x didn't match\n", os); 233 return (0); 234 } 235 236 /* Initialize the OS fingerprint system */ 237 void 238 pf_osfp_initialize(void) 239 { 240 pool_init(&pf_osfp_entry_pl, sizeof(struct pf_osfp_entry), 0, 0, 0, 241 "pfosfpen", &pool_allocator_nointr); 242 pool_init(&pf_osfp_pl, sizeof(struct pf_os_fingerprint), 0, 0, 0, 243 "pfosfp", &pool_allocator_nointr); 244 SLIST_INIT(&pf_osfp_list); 245 } 246 247 #ifdef _LKM 248 void 249 pf_osfp_destroy(void) 250 { 251 pf_osfp_flush(); 252 253 pool_destroy(&pf_osfp_pl); 254 pool_destroy(&pf_osfp_entry_pl); 255 } 256 #endif 257 258 /* Flush the fingerprint list */ 259 void 260 pf_osfp_flush(void) 261 { 262 struct pf_os_fingerprint *fp; 263 struct pf_osfp_entry *entry; 264 265 while ((fp = SLIST_FIRST(&pf_osfp_list))) { 266 SLIST_REMOVE_HEAD(&pf_osfp_list, fp_next); 267 while ((entry = SLIST_FIRST(&fp->fp_oses))) { 268 SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry); 269 pool_put(&pf_osfp_entry_pl, entry); 270 } 271 pool_put(&pf_osfp_pl, fp); 272 } 273 } 274 275 276 /* Add a fingerprint */ 277 int 278 pf_osfp_add(struct pf_osfp_ioctl *fpioc) 279 { 280 struct pf_os_fingerprint *fp, fpadd; 281 struct pf_osfp_entry *entry; 282 283 memset(&fpadd, 0, sizeof(fpadd)); 284 fpadd.fp_tcpopts = fpioc->fp_tcpopts; 285 fpadd.fp_wsize = fpioc->fp_wsize; 286 fpadd.fp_psize = fpioc->fp_psize; 287 fpadd.fp_mss = fpioc->fp_mss; 288 fpadd.fp_flags = fpioc->fp_flags; 289 fpadd.fp_optcnt = fpioc->fp_optcnt; 290 fpadd.fp_wscale = fpioc->fp_wscale; 291 fpadd.fp_ttl = fpioc->fp_ttl; 292 293 DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d " 294 "(TS=%s,M=%s%d,W=%s%d) %x\n", 295 fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm, 296 fpioc->fp_os.fp_subtype_nm, 297 (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" : 298 (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" : 299 (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" : 300 (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "", 301 fpadd.fp_wsize, 302 fpadd.fp_ttl, 303 (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0, 304 (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" : 305 (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "", 306 fpadd.fp_psize, 307 (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt, 308 (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "", 309 (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" : 310 (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "", 311 fpadd.fp_mss, 312 (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" : 313 (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "", 314 fpadd.fp_wscale, 315 fpioc->fp_os.fp_os); 316 317 318 if ((fp = pf_osfp_find_exact(&pf_osfp_list, &fpadd))) { 319 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) { 320 if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os)) 321 return (EEXIST); 322 } 323 if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL) 324 return (ENOMEM); 325 } else { 326 if ((fp = pool_get(&pf_osfp_pl, PR_NOWAIT)) == NULL) 327 return (ENOMEM); 328 memset(fp, 0, sizeof(*fp)); 329 fp->fp_tcpopts = fpioc->fp_tcpopts; 330 fp->fp_wsize = fpioc->fp_wsize; 331 fp->fp_psize = fpioc->fp_psize; 332 fp->fp_mss = fpioc->fp_mss; 333 fp->fp_flags = fpioc->fp_flags; 334 fp->fp_optcnt = fpioc->fp_optcnt; 335 fp->fp_wscale = fpioc->fp_wscale; 336 fp->fp_ttl = fpioc->fp_ttl; 337 SLIST_INIT(&fp->fp_oses); 338 if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL) { 339 pool_put(&pf_osfp_pl, fp); 340 return (ENOMEM); 341 } 342 pf_osfp_insert(&pf_osfp_list, fp); 343 } 344 memcpy(entry, &fpioc->fp_os, sizeof(*entry)); 345 346 /* Make sure the strings are NUL terminated */ 347 entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0'; 348 entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0'; 349 entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0'; 350 351 SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry); 352 353 #ifdef PFDEBUG 354 if ((fp = pf_osfp_validate())) 355 printf("Invalid fingerprint list\n"); 356 #endif /* PFDEBUG */ 357 return (0); 358 } 359 360 361 /* Find a fingerprint in the list */ 362 struct pf_os_fingerprint * 363 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find, 364 u_int8_t ttldiff) 365 { 366 struct pf_os_fingerprint *f; 367 368 #define MATCH_INT(_MOD, _DC, _field) \ 369 if ((f->fp_flags & _DC) == 0) { \ 370 if ((f->fp_flags & _MOD) == 0) { \ 371 if (f->_field != find->_field) \ 372 continue; \ 373 } else { \ 374 if (f->_field == 0 || find->_field % f->_field) \ 375 continue; \ 376 } \ 377 } 378 379 SLIST_FOREACH(f, list, fp_next) { 380 if (f->fp_tcpopts != find->fp_tcpopts || 381 f->fp_optcnt != find->fp_optcnt || 382 f->fp_ttl < find->fp_ttl || 383 f->fp_ttl - find->fp_ttl > ttldiff || 384 (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) != 385 (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0))) 386 continue; 387 388 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize) 389 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss) 390 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale) 391 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) { 392 if (f->fp_flags & PF_OSFP_WSIZE_MSS) { 393 if (find->fp_mss == 0) 394 continue; 395 396 /* Some "smart" NAT devices and DSL routers will tweak the MSS size and 397 * will set it to whatever is suitable for the link type. 398 */ 399 #define SMART_MSS 1460 400 if ((find->fp_wsize % find->fp_mss || 401 find->fp_wsize / find->fp_mss != 402 f->fp_wsize) && 403 (find->fp_wsize % SMART_MSS || 404 find->fp_wsize / SMART_MSS != 405 f->fp_wsize)) 406 continue; 407 } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) { 408 if (find->fp_mss == 0) 409 continue; 410 411 #define MTUOFF (sizeof(struct ip) + sizeof(struct tcphdr)) 412 #define SMART_MTU (SMART_MSS + MTUOFF) 413 if ((find->fp_wsize % (find->fp_mss + MTUOFF) || 414 find->fp_wsize / (find->fp_mss + MTUOFF) != 415 f->fp_wsize) && 416 (find->fp_wsize % SMART_MTU || 417 find->fp_wsize / SMART_MTU != 418 f->fp_wsize)) 419 continue; 420 } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) { 421 if (f->fp_wsize == 0 || find->fp_wsize % 422 f->fp_wsize) 423 continue; 424 } else { 425 if (f->fp_wsize != find->fp_wsize) 426 continue; 427 } 428 } 429 return (f); 430 } 431 432 return (NULL); 433 } 434 435 /* Find an exact fingerprint in the list */ 436 struct pf_os_fingerprint * 437 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find) 438 { 439 struct pf_os_fingerprint *f; 440 441 SLIST_FOREACH(f, list, fp_next) { 442 if (f->fp_tcpopts == find->fp_tcpopts && 443 f->fp_wsize == find->fp_wsize && 444 f->fp_psize == find->fp_psize && 445 f->fp_mss == find->fp_mss && 446 f->fp_flags == find->fp_flags && 447 f->fp_optcnt == find->fp_optcnt && 448 f->fp_wscale == find->fp_wscale && 449 f->fp_ttl == find->fp_ttl) 450 return (f); 451 } 452 453 return (NULL); 454 } 455 456 /* Insert a fingerprint into the list */ 457 void 458 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins) 459 { 460 struct pf_os_fingerprint *f, *prev = NULL; 461 462 /* XXX need to go semi tree based. can key on tcp options */ 463 464 SLIST_FOREACH(f, list, fp_next) 465 prev = f; 466 if (prev) 467 SLIST_INSERT_AFTER(prev, ins, fp_next); 468 else 469 SLIST_INSERT_HEAD(list, ins, fp_next); 470 } 471 472 /* Fill a fingerprint by its number (from an ioctl) */ 473 int 474 pf_osfp_get(struct pf_osfp_ioctl *fpioc) 475 { 476 struct pf_os_fingerprint *fp; 477 struct pf_osfp_entry *entry; 478 int num = fpioc->fp_getnum; 479 int i = 0; 480 481 482 memset(fpioc, 0, sizeof(*fpioc)); 483 SLIST_FOREACH(fp, &pf_osfp_list, fp_next) { 484 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) { 485 if (i++ == num) { 486 fpioc->fp_mss = fp->fp_mss; 487 fpioc->fp_wsize = fp->fp_wsize; 488 fpioc->fp_flags = fp->fp_flags; 489 fpioc->fp_psize = fp->fp_psize; 490 fpioc->fp_ttl = fp->fp_ttl; 491 fpioc->fp_wscale = fp->fp_wscale; 492 fpioc->fp_getnum = num; 493 memcpy(&fpioc->fp_os, entry, 494 sizeof(fpioc->fp_os)); 495 return (0); 496 } 497 } 498 } 499 500 return (EBUSY); 501 } 502 503 504 /* Validate that each signature is reachable */ 505 struct pf_os_fingerprint * 506 pf_osfp_validate(void) 507 { 508 struct pf_os_fingerprint *f, *f2, find; 509 510 SLIST_FOREACH(f, &pf_osfp_list, fp_next) { 511 memcpy(&find, f, sizeof(find)); 512 513 /* We do a few MSS/th_win percolations to make things unique */ 514 if (find.fp_mss == 0) 515 find.fp_mss = 128; 516 if (f->fp_flags & PF_OSFP_WSIZE_MSS) 517 find.fp_wsize *= find.fp_mss, 1; 518 else if (f->fp_flags & PF_OSFP_WSIZE_MTU) 519 find.fp_wsize *= (find.fp_mss + 40); 520 else if (f->fp_flags & PF_OSFP_WSIZE_MOD) 521 find.fp_wsize *= 2; 522 if (f != (f2 = pf_osfp_find(&pf_osfp_list, &find, 0))) { 523 if (f2) 524 printf("Found \"%s %s %s\" instead of " 525 "\"%s %s %s\"\n", 526 SLIST_FIRST(&f2->fp_oses)->fp_class_nm, 527 SLIST_FIRST(&f2->fp_oses)->fp_version_nm, 528 SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm, 529 SLIST_FIRST(&f->fp_oses)->fp_class_nm, 530 SLIST_FIRST(&f->fp_oses)->fp_version_nm, 531 SLIST_FIRST(&f->fp_oses)->fp_subtype_nm); 532 else 533 printf("Couldn't find \"%s %s %s\"\n", 534 SLIST_FIRST(&f->fp_oses)->fp_class_nm, 535 SLIST_FIRST(&f->fp_oses)->fp_version_nm, 536 SLIST_FIRST(&f->fp_oses)->fp_subtype_nm); 537 return (f); 538 } 539 } 540 return (NULL); 541 } 542
Indexes created Fri Sep 26 20:09:58 GMT 2025