pf_osfp.c revision 1.1
1 /* $OpenBSD: pf_osfp.c,v 1.9 2004/01/04 20:08:42 pvalchev Exp $ */ 2 3 /* 4 * Copyright (c) 2003 Mike Frantzen <frantzen (at) w4g.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 * 18 */ 19 20 #include <sys/param.h> 21 #include <sys/socket.h> 22 #ifdef _KERNEL 23 # include <sys/systm.h> 24 #endif /* _KERNEL */ 25 #include <sys/mbuf.h> 26 27 #include <netinet/in.h> 28 #include <netinet/in_systm.h> 29 #include <netinet/ip.h> 30 #include <netinet/tcp.h> 31 32 #include <net/if.h> 33 #include <net/pfvar.h> 34 35 #ifdef INET6 36 #include <netinet/ip6.h> 37 #endif /* INET6 */ 38 39 40 #ifdef _KERNEL 41 # define DPFPRINTF(format, x...) \ 42 if (pf_status.debug >= PF_DEBUG_NOISY) \ 43 printf(format , ##x) 44 typedef struct pool pool_t; 45 46 #else 47 /* Userland equivalents so we can lend code to tcpdump et al. */ 48 49 # include <arpa/inet.h> 50 # include <errno.h> 51 # include <stdio.h> 52 # include <stdlib.h> 53 # include <string.h> 54 # define pool_t int 55 # define pool_get(pool, flags) malloc(*(pool)) 56 # define pool_put(pool, item) free(item) 57 # define pool_init(pool, size, a, ao, f, m, p) (*(pool)) = (size) 58 59 # ifdef PFDEBUG 60 # include <sys/stdarg.h> 61 # define DPFPRINTF(format, x...) fprintf(stderr, format , ##x) 62 # else 63 # define DPFPRINTF(format, x...) ((void)0) 64 # endif /* PFDEBUG */ 65 #endif /* _KERNEL */ 66 67 68 SLIST_HEAD(pf_osfp_list, pf_os_fingerprint) pf_osfp_list; 69 pool_t pf_osfp_entry_pl; 70 pool_t pf_osfp_pl; 71 72 struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *, 73 struct pf_os_fingerprint *, u_int8_t); 74 struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *, 75 struct pf_os_fingerprint *); 76 void pf_osfp_insert(struct pf_osfp_list *, 77 struct pf_os_fingerprint *); 78 79 80 #ifdef _KERNEL 81 /* 82 * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only) 83 * Returns the list of possible OSes. 84 */ 85 struct pf_osfp_enlist * 86 pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off, 87 const struct tcphdr *tcp) 88 { 89 struct ip *ip; 90 char hdr[60]; 91 92 /* XXX don't have a fingerprint database for IPv6 :-( */ 93 if (pd->af != PF_INET || pd->proto != IPPROTO_TCP || (tcp->th_off << 2) 94 < sizeof(*tcp)) 95 return (NULL); 96 97 ip = mtod(m, struct ip *); 98 if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL, pd->af)) 99 return (NULL); 100 101 return (pf_osfp_fingerprint_hdr(ip, (struct tcphdr *)hdr)); 102 } 103 #endif /* _KERNEL */ 104 105 struct pf_osfp_enlist * 106 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct tcphdr *tcp) 107 { 108 struct pf_os_fingerprint fp, *fpresult; 109 int cnt, optlen = 0; 110 const u_int8_t *optp; 111 112 if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN || (ip->ip_off & 113 htons(IP_OFFMASK))) 114 return (NULL); 115 116 memset(&fp, 0, sizeof(fp)); 117 118 fp.fp_psize = ntohs(ip->ip_len); 119 fp.fp_ttl = ip->ip_ttl; 120 if (ip->ip_off & htons(IP_DF)) 121 fp.fp_flags |= PF_OSFP_DF; 122 fp.fp_wsize = ntohs(tcp->th_win); 123 124 125 cnt = (tcp->th_off << 2) - sizeof(*tcp); 126 optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp)); 127 for (; cnt > 0; cnt -= optlen, optp += optlen) { 128 if (*optp == TCPOPT_EOL) 129 break; 130 131 fp.fp_optcnt++; 132 if (*optp == TCPOPT_NOP) { 133 fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) | 134 PF_OSFP_TCPOPT_NOP; 135 optlen = 1; 136 } else { 137 if (cnt < 2) 138 return (NULL); 139 optlen = optp[1]; 140 if (optlen > cnt || optlen < 2) 141 return (NULL); 142 switch (*optp) { 143 case TCPOPT_MAXSEG: 144 if (optlen >= TCPOLEN_MAXSEG) 145 memcpy(&fp.fp_mss, &optp[2], 146 sizeof(fp.fp_mss)); 147 fp.fp_tcpopts = (fp.fp_tcpopts << 148 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS; 149 NTOHS(fp.fp_mss); 150 break; 151 case TCPOPT_WINDOW: 152 if (optlen >= TCPOLEN_WINDOW) 153 memcpy(&fp.fp_wscale, &optp[2], 154 sizeof(fp.fp_wscale)); 155 NTOHS(fp.fp_wscale); 156 fp.fp_tcpopts = (fp.fp_tcpopts << 157 PF_OSFP_TCPOPT_BITS) | 158 PF_OSFP_TCPOPT_WSCALE; 159 break; 160 case TCPOPT_SACK_PERMITTED: 161 fp.fp_tcpopts = (fp.fp_tcpopts << 162 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK; 163 break; 164 case TCPOPT_TIMESTAMP: 165 if (optlen >= TCPOLEN_TIMESTAMP) { 166 u_int32_t ts; 167 memcpy(&ts, &optp[2], sizeof(ts)); 168 if (ts == 0) 169 fp.fp_flags |= PF_OSFP_TS0; 170 171 } 172 fp.fp_tcpopts = (fp.fp_tcpopts << 173 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS; 174 break; 175 default: 176 return (NULL); 177 } 178 } 179 optlen = MAX(optlen, 1); /* paranoia */ 180 } 181 182 DPFPRINTF("fingerprinted %s:%d %d:%d:%d:%d:%llx (%d) " 183 "(TS=%s,M=%s%d,W=%s%d)\n", 184 inet_ntoa(ip->ip_src), ntohs(tcp->th_sport), 185 fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0, 186 fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt, 187 (fp.fp_flags & PF_OSFP_TS0) ? "0" : "", 188 (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" : 189 (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "", 190 fp.fp_mss, 191 (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" : 192 (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "", 193 fp.fp_wscale); 194 195 if ((fpresult = pf_osfp_find(&pf_osfp_list, &fp, 196 PF_OSFP_MAXTTL_OFFSET))) 197 return (&fpresult->fp_oses); 198 return (NULL); 199 } 200 201 /* Match a fingerprint ID against a list of OSes */ 202 int 203 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os) 204 { 205 struct pf_osfp_entry *entry; 206 int os_class, os_version, os_subtype; 207 int en_class, en_version, en_subtype; 208 209 if (os == PF_OSFP_ANY) 210 return (1); 211 if (list == NULL) { 212 DPFPRINTF("osfp no match against %x\n", os); 213 return (os == PF_OSFP_UNKNOWN); 214 } 215 PF_OSFP_UNPACK(os, os_class, os_version, os_subtype); 216 SLIST_FOREACH(entry, list, fp_entry) { 217 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype); 218 if ((os_class == PF_OSFP_ANY || en_class == os_class) && 219 (os_version == PF_OSFP_ANY || en_version == os_version) && 220 (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) { 221 DPFPRINTF("osfp matched %s %s %s %x==%x\n", 222 entry->fp_class_nm, entry->fp_version_nm, 223 entry->fp_subtype_nm, os, entry->fp_os); 224 return (1); 225 } 226 } 227 DPFPRINTF("fingerprint 0x%x didn't match\n", os); 228 return (0); 229 } 230 231 /* Initialize the OS fingerprint system */ 232 void 233 pf_osfp_initialize(void) 234 { 235 pool_init(&pf_osfp_entry_pl, sizeof(struct pf_osfp_entry), 0, 0, 0, 236 "pfosfpen", NULL); 237 pool_init(&pf_osfp_pl, sizeof(struct pf_os_fingerprint), 0, 0, 0, 238 "pfosfp", NULL); 239 SLIST_INIT(&pf_osfp_list); 240 } 241 242 /* Flush the fingerprint list */ 243 void 244 pf_osfp_flush(void) 245 { 246 struct pf_os_fingerprint *fp; 247 struct pf_osfp_entry *entry; 248 249 while ((fp = SLIST_FIRST(&pf_osfp_list))) { 250 SLIST_REMOVE_HEAD(&pf_osfp_list, fp_next); 251 while ((entry = SLIST_FIRST(&fp->fp_oses))) { 252 SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry); 253 pool_put(&pf_osfp_entry_pl, entry); 254 } 255 pool_put(&pf_osfp_pl, fp); 256 } 257 } 258 259 260 /* Add a fingerprint */ 261 int 262 pf_osfp_add(struct pf_osfp_ioctl *fpioc) 263 { 264 struct pf_os_fingerprint *fp, fpadd; 265 struct pf_osfp_entry *entry; 266 267 memset(&fpadd, 0, sizeof(fpadd)); 268 fpadd.fp_tcpopts = fpioc->fp_tcpopts; 269 fpadd.fp_wsize = fpioc->fp_wsize; 270 fpadd.fp_psize = fpioc->fp_psize; 271 fpadd.fp_mss = fpioc->fp_mss; 272 fpadd.fp_flags = fpioc->fp_flags; 273 fpadd.fp_optcnt = fpioc->fp_optcnt; 274 fpadd.fp_wscale = fpioc->fp_wscale; 275 fpadd.fp_ttl = fpioc->fp_ttl; 276 277 DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d " 278 "(TS=%s,M=%s%d,W=%s%d) %x\n", 279 fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm, 280 fpioc->fp_os.fp_subtype_nm, 281 (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" : 282 (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" : 283 (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" : 284 (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "", 285 fpadd.fp_wsize, 286 fpadd.fp_ttl, 287 (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0, 288 (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" : 289 (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "", 290 fpadd.fp_psize, 291 (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt, 292 (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "", 293 (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" : 294 (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "", 295 fpadd.fp_mss, 296 (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" : 297 (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "", 298 fpadd.fp_wscale, 299 fpioc->fp_os.fp_os); 300 301 302 if ((fp = pf_osfp_find_exact(&pf_osfp_list, &fpadd))) { 303 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) { 304 if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os)) 305 return (EEXIST); 306 } 307 if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL) 308 return (ENOMEM); 309 } else { 310 if ((fp = pool_get(&pf_osfp_pl, PR_NOWAIT)) == NULL) 311 return (ENOMEM); 312 memset(fp, 0, sizeof(*fp)); 313 fp->fp_tcpopts = fpioc->fp_tcpopts; 314 fp->fp_wsize = fpioc->fp_wsize; 315 fp->fp_psize = fpioc->fp_psize; 316 fp->fp_mss = fpioc->fp_mss; 317 fp->fp_flags = fpioc->fp_flags; 318 fp->fp_optcnt = fpioc->fp_optcnt; 319 fp->fp_wscale = fpioc->fp_wscale; 320 fp->fp_ttl = fpioc->fp_ttl; 321 SLIST_INIT(&fp->fp_oses); 322 if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL) { 323 pool_put(&pf_osfp_pl, fp); 324 return (ENOMEM); 325 } 326 pf_osfp_insert(&pf_osfp_list, fp); 327 } 328 memcpy(entry, &fpioc->fp_os, sizeof(*entry)); 329 330 /* Make sure the strings are NUL terminated */ 331 entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0'; 332 entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0'; 333 entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0'; 334 335 SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry); 336 337 #ifdef PFDEBUG 338 if ((fp = pf_osfp_validate())) 339 printf("Invalid fingerprint list\n"); 340 #endif /* PFDEBUG */ 341 return (0); 342 } 343 344 345 /* Find a fingerprint in the list */ 346 struct pf_os_fingerprint * 347 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find, 348 u_int8_t ttldiff) 349 { 350 struct pf_os_fingerprint *f; 351 352 #define MATCH_INT(_MOD, _DC, _field) \ 353 if ((f->fp_flags & _DC) == 0) { \ 354 if ((f->fp_flags & _MOD) == 0) { \ 355 if (f->_field != find->_field) \ 356 continue; \ 357 } else { \ 358 if (f->_field == 0 || find->_field % f->_field) \ 359 continue; \ 360 } \ 361 } 362 363 SLIST_FOREACH(f, list, fp_next) { 364 if (f->fp_tcpopts != find->fp_tcpopts || 365 f->fp_optcnt != find->fp_optcnt || 366 f->fp_ttl < find->fp_ttl || 367 f->fp_ttl - find->fp_ttl > ttldiff || 368 (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) != 369 (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0))) 370 continue; 371 372 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize) 373 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss) 374 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale) 375 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) { 376 if (f->fp_flags & PF_OSFP_WSIZE_MSS) { 377 if (find->fp_mss == 0) 378 continue; 379 380 /* Some "smart" NAT devices and DSL routers will tweak the MSS size and 381 * will set it to whatever is suitable for the link type. 382 */ 383 #define SMART_MSS 1460 384 if ((find->fp_wsize % find->fp_mss || 385 find->fp_wsize / find->fp_mss != 386 f->fp_wsize) && 387 (find->fp_wsize % SMART_MSS || 388 find->fp_wsize / SMART_MSS != 389 f->fp_wsize)) 390 continue; 391 } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) { 392 if (find->fp_mss == 0) 393 continue; 394 395 #define MTUOFF (sizeof(struct ip) + sizeof(struct tcphdr)) 396 #define SMART_MTU (SMART_MSS + MTUOFF) 397 if ((find->fp_wsize % (find->fp_mss + MTUOFF) || 398 find->fp_wsize / (find->fp_mss + MTUOFF) != 399 f->fp_wsize) && 400 (find->fp_wsize % SMART_MTU || 401 find->fp_wsize / SMART_MTU != 402 f->fp_wsize)) 403 continue; 404 } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) { 405 if (f->fp_wsize == 0 || find->fp_wsize % 406 f->fp_wsize) 407 continue; 408 } else { 409 if (f->fp_wsize != find->fp_wsize) 410 continue; 411 } 412 } 413 return (f); 414 } 415 416 return (NULL); 417 } 418 419 /* Find an exact fingerprint in the list */ 420 struct pf_os_fingerprint * 421 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find) 422 { 423 struct pf_os_fingerprint *f; 424 425 SLIST_FOREACH(f, list, fp_next) { 426 if (f->fp_tcpopts == find->fp_tcpopts && 427 f->fp_wsize == find->fp_wsize && 428 f->fp_psize == find->fp_psize && 429 f->fp_mss == find->fp_mss && 430 f->fp_flags == find->fp_flags && 431 f->fp_optcnt == find->fp_optcnt && 432 f->fp_wscale == find->fp_wscale && 433 f->fp_ttl == find->fp_ttl) 434 return (f); 435 } 436 437 return (NULL); 438 } 439 440 /* Insert a fingerprint into the list */ 441 void 442 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins) 443 { 444 struct pf_os_fingerprint *f, *prev = NULL; 445 446 /* XXX need to go semi tree based. can key on tcp options */ 447 448 SLIST_FOREACH(f, list, fp_next) 449 prev = f; 450 if (prev) 451 SLIST_INSERT_AFTER(prev, ins, fp_next); 452 else 453 SLIST_INSERT_HEAD(list, ins, fp_next); 454 } 455 456 /* Fill a fingerprint by its number (from an ioctl) */ 457 int 458 pf_osfp_get(struct pf_osfp_ioctl *fpioc) 459 { 460 struct pf_os_fingerprint *fp; 461 struct pf_osfp_entry *entry; 462 int num = fpioc->fp_getnum; 463 int i = 0; 464 465 466 memset(fpioc, 0, sizeof(*fpioc)); 467 SLIST_FOREACH(fp, &pf_osfp_list, fp_next) { 468 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) { 469 if (i++ == num) { 470 fpioc->fp_mss = fp->fp_mss; 471 fpioc->fp_wsize = fp->fp_wsize; 472 fpioc->fp_flags = fp->fp_flags; 473 fpioc->fp_psize = fp->fp_psize; 474 fpioc->fp_ttl = fp->fp_ttl; 475 fpioc->fp_wscale = fp->fp_wscale; 476 fpioc->fp_getnum = num; 477 memcpy(&fpioc->fp_os, entry, 478 sizeof(fpioc->fp_os)); 479 return (0); 480 } 481 } 482 } 483 484 return (EBUSY); 485 } 486 487 488 /* Validate that each signature is reachable */ 489 struct pf_os_fingerprint * 490 pf_osfp_validate(void) 491 { 492 struct pf_os_fingerprint *f, *f2, find; 493 494 SLIST_FOREACH(f, &pf_osfp_list, fp_next) { 495 memcpy(&find, f, sizeof(find)); 496 497 /* We do a few MSS/th_win percolations to make things unique */ 498 if (find.fp_mss == 0) 499 find.fp_mss = 128; 500 if (f->fp_flags & PF_OSFP_WSIZE_MSS) 501 find.fp_wsize *= find.fp_mss, 1; 502 else if (f->fp_flags & PF_OSFP_WSIZE_MTU) 503 find.fp_wsize *= (find.fp_mss + 40); 504 else if (f->fp_flags & PF_OSFP_WSIZE_MOD) 505 find.fp_wsize *= 2; 506 if (f != (f2 = pf_osfp_find(&pf_osfp_list, &find, 0))) { 507 if (f2) 508 printf("Found \"%s %s %s\" instead of " 509 "\"%s %s %s\"\n", 510 SLIST_FIRST(&f2->fp_oses)->fp_class_nm, 511 SLIST_FIRST(&f2->fp_oses)->fp_version_nm, 512 SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm, 513 SLIST_FIRST(&f->fp_oses)->fp_class_nm, 514 SLIST_FIRST(&f->fp_oses)->fp_version_nm, 515 SLIST_FIRST(&f->fp_oses)->fp_subtype_nm); 516 else 517 printf("Couldn't find \"%s %s %s\"\n", 518 SLIST_FIRST(&f->fp_oses)->fp_class_nm, 519 SLIST_FIRST(&f->fp_oses)->fp_version_nm, 520 SLIST_FIRST(&f->fp_oses)->fp_subtype_nm); 521 return (f); 522 } 523 } 524 return (NULL); 525 } 526
Indexes created Fri Sep 26 08:10:20 GMT 2025