pf_osfp.c revision 1.2
1 /* $NetBSD: pf_osfp.c,v 1.2 2004/06/22 14:17:08 itojun Exp $ */ 2 /* $OpenBSD: pf_osfp.c,v 1.9 2004/01/04 20:08:42 pvalchev 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", NULL); 242 pool_init(&pf_osfp_pl, sizeof(struct pf_os_fingerprint), 0, 0, 0, 243 "pfosfp", NULL); 244 SLIST_INIT(&pf_osfp_list); 245 } 246 247 /* Flush the fingerprint list */ 248 void 249 pf_osfp_flush(void) 250 { 251 struct pf_os_fingerprint *fp; 252 struct pf_osfp_entry *entry; 253 254 while ((fp = SLIST_FIRST(&pf_osfp_list))) { 255 SLIST_REMOVE_HEAD(&pf_osfp_list, fp_next); 256 while ((entry = SLIST_FIRST(&fp->fp_oses))) { 257 SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry); 258 pool_put(&pf_osfp_entry_pl, entry); 259 } 260 pool_put(&pf_osfp_pl, fp); 261 } 262 } 263 264 265 /* Add a fingerprint */ 266 int 267 pf_osfp_add(struct pf_osfp_ioctl *fpioc) 268 { 269 struct pf_os_fingerprint *fp, fpadd; 270 struct pf_osfp_entry *entry; 271 272 memset(&fpadd, 0, sizeof(fpadd)); 273 fpadd.fp_tcpopts = fpioc->fp_tcpopts; 274 fpadd.fp_wsize = fpioc->fp_wsize; 275 fpadd.fp_psize = fpioc->fp_psize; 276 fpadd.fp_mss = fpioc->fp_mss; 277 fpadd.fp_flags = fpioc->fp_flags; 278 fpadd.fp_optcnt = fpioc->fp_optcnt; 279 fpadd.fp_wscale = fpioc->fp_wscale; 280 fpadd.fp_ttl = fpioc->fp_ttl; 281 282 DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d " 283 "(TS=%s,M=%s%d,W=%s%d) %x\n", 284 fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm, 285 fpioc->fp_os.fp_subtype_nm, 286 (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" : 287 (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" : 288 (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" : 289 (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "", 290 fpadd.fp_wsize, 291 fpadd.fp_ttl, 292 (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0, 293 (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" : 294 (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "", 295 fpadd.fp_psize, 296 (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt, 297 (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "", 298 (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" : 299 (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "", 300 fpadd.fp_mss, 301 (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" : 302 (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "", 303 fpadd.fp_wscale, 304 fpioc->fp_os.fp_os); 305 306 307 if ((fp = pf_osfp_find_exact(&pf_osfp_list, &fpadd))) { 308 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) { 309 if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os)) 310 return (EEXIST); 311 } 312 if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL) 313 return (ENOMEM); 314 } else { 315 if ((fp = pool_get(&pf_osfp_pl, PR_NOWAIT)) == NULL) 316 return (ENOMEM); 317 memset(fp, 0, sizeof(*fp)); 318 fp->fp_tcpopts = fpioc->fp_tcpopts; 319 fp->fp_wsize = fpioc->fp_wsize; 320 fp->fp_psize = fpioc->fp_psize; 321 fp->fp_mss = fpioc->fp_mss; 322 fp->fp_flags = fpioc->fp_flags; 323 fp->fp_optcnt = fpioc->fp_optcnt; 324 fp->fp_wscale = fpioc->fp_wscale; 325 fp->fp_ttl = fpioc->fp_ttl; 326 SLIST_INIT(&fp->fp_oses); 327 if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL) { 328 pool_put(&pf_osfp_pl, fp); 329 return (ENOMEM); 330 } 331 pf_osfp_insert(&pf_osfp_list, fp); 332 } 333 memcpy(entry, &fpioc->fp_os, sizeof(*entry)); 334 335 /* Make sure the strings are NUL terminated */ 336 entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0'; 337 entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0'; 338 entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0'; 339 340 SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry); 341 342 #ifdef PFDEBUG 343 if ((fp = pf_osfp_validate())) 344 printf("Invalid fingerprint list\n"); 345 #endif /* PFDEBUG */ 346 return (0); 347 } 348 349 350 /* Find a fingerprint in the list */ 351 struct pf_os_fingerprint * 352 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find, 353 u_int8_t ttldiff) 354 { 355 struct pf_os_fingerprint *f; 356 357 #define MATCH_INT(_MOD, _DC, _field) \ 358 if ((f->fp_flags & _DC) == 0) { \ 359 if ((f->fp_flags & _MOD) == 0) { \ 360 if (f->_field != find->_field) \ 361 continue; \ 362 } else { \ 363 if (f->_field == 0 || find->_field % f->_field) \ 364 continue; \ 365 } \ 366 } 367 368 SLIST_FOREACH(f, list, fp_next) { 369 if (f->fp_tcpopts != find->fp_tcpopts || 370 f->fp_optcnt != find->fp_optcnt || 371 f->fp_ttl < find->fp_ttl || 372 f->fp_ttl - find->fp_ttl > ttldiff || 373 (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) != 374 (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0))) 375 continue; 376 377 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize) 378 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss) 379 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale) 380 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) { 381 if (f->fp_flags & PF_OSFP_WSIZE_MSS) { 382 if (find->fp_mss == 0) 383 continue; 384 385 /* Some "smart" NAT devices and DSL routers will tweak the MSS size and 386 * will set it to whatever is suitable for the link type. 387 */ 388 #define SMART_MSS 1460 389 if ((find->fp_wsize % find->fp_mss || 390 find->fp_wsize / find->fp_mss != 391 f->fp_wsize) && 392 (find->fp_wsize % SMART_MSS || 393 find->fp_wsize / SMART_MSS != 394 f->fp_wsize)) 395 continue; 396 } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) { 397 if (find->fp_mss == 0) 398 continue; 399 400 #define MTUOFF (sizeof(struct ip) + sizeof(struct tcphdr)) 401 #define SMART_MTU (SMART_MSS + MTUOFF) 402 if ((find->fp_wsize % (find->fp_mss + MTUOFF) || 403 find->fp_wsize / (find->fp_mss + MTUOFF) != 404 f->fp_wsize) && 405 (find->fp_wsize % SMART_MTU || 406 find->fp_wsize / SMART_MTU != 407 f->fp_wsize)) 408 continue; 409 } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) { 410 if (f->fp_wsize == 0 || find->fp_wsize % 411 f->fp_wsize) 412 continue; 413 } else { 414 if (f->fp_wsize != find->fp_wsize) 415 continue; 416 } 417 } 418 return (f); 419 } 420 421 return (NULL); 422 } 423 424 /* Find an exact fingerprint in the list */ 425 struct pf_os_fingerprint * 426 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find) 427 { 428 struct pf_os_fingerprint *f; 429 430 SLIST_FOREACH(f, list, fp_next) { 431 if (f->fp_tcpopts == find->fp_tcpopts && 432 f->fp_wsize == find->fp_wsize && 433 f->fp_psize == find->fp_psize && 434 f->fp_mss == find->fp_mss && 435 f->fp_flags == find->fp_flags && 436 f->fp_optcnt == find->fp_optcnt && 437 f->fp_wscale == find->fp_wscale && 438 f->fp_ttl == find->fp_ttl) 439 return (f); 440 } 441 442 return (NULL); 443 } 444 445 /* Insert a fingerprint into the list */ 446 void 447 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins) 448 { 449 struct pf_os_fingerprint *f, *prev = NULL; 450 451 /* XXX need to go semi tree based. can key on tcp options */ 452 453 SLIST_FOREACH(f, list, fp_next) 454 prev = f; 455 if (prev) 456 SLIST_INSERT_AFTER(prev, ins, fp_next); 457 else 458 SLIST_INSERT_HEAD(list, ins, fp_next); 459 } 460 461 /* Fill a fingerprint by its number (from an ioctl) */ 462 int 463 pf_osfp_get(struct pf_osfp_ioctl *fpioc) 464 { 465 struct pf_os_fingerprint *fp; 466 struct pf_osfp_entry *entry; 467 int num = fpioc->fp_getnum; 468 int i = 0; 469 470 471 memset(fpioc, 0, sizeof(*fpioc)); 472 SLIST_FOREACH(fp, &pf_osfp_list, fp_next) { 473 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) { 474 if (i++ == num) { 475 fpioc->fp_mss = fp->fp_mss; 476 fpioc->fp_wsize = fp->fp_wsize; 477 fpioc->fp_flags = fp->fp_flags; 478 fpioc->fp_psize = fp->fp_psize; 479 fpioc->fp_ttl = fp->fp_ttl; 480 fpioc->fp_wscale = fp->fp_wscale; 481 fpioc->fp_getnum = num; 482 memcpy(&fpioc->fp_os, entry, 483 sizeof(fpioc->fp_os)); 484 return (0); 485 } 486 } 487 } 488 489 return (EBUSY); 490 } 491 492 493 /* Validate that each signature is reachable */ 494 struct pf_os_fingerprint * 495 pf_osfp_validate(void) 496 { 497 struct pf_os_fingerprint *f, *f2, find; 498 499 SLIST_FOREACH(f, &pf_osfp_list, fp_next) { 500 memcpy(&find, f, sizeof(find)); 501 502 /* We do a few MSS/th_win percolations to make things unique */ 503 if (find.fp_mss == 0) 504 find.fp_mss = 128; 505 if (f->fp_flags & PF_OSFP_WSIZE_MSS) 506 find.fp_wsize *= find.fp_mss, 1; 507 else if (f->fp_flags & PF_OSFP_WSIZE_MTU) 508 find.fp_wsize *= (find.fp_mss + 40); 509 else if (f->fp_flags & PF_OSFP_WSIZE_MOD) 510 find.fp_wsize *= 2; 511 if (f != (f2 = pf_osfp_find(&pf_osfp_list, &find, 0))) { 512 if (f2) 513 printf("Found \"%s %s %s\" instead of " 514 "\"%s %s %s\"\n", 515 SLIST_FIRST(&f2->fp_oses)->fp_class_nm, 516 SLIST_FIRST(&f2->fp_oses)->fp_version_nm, 517 SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm, 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 else 522 printf("Couldn't find \"%s %s %s\"\n", 523 SLIST_FIRST(&f->fp_oses)->fp_class_nm, 524 SLIST_FIRST(&f->fp_oses)->fp_version_nm, 525 SLIST_FIRST(&f->fp_oses)->fp_subtype_nm); 526 return (f); 527 } 528 } 529 return (NULL); 530 } 531
Indexes created Sun Sep 28 16:09:52 GMT 2025