2 * SPDX-License-Identifier: ISC
4 * Copyright (c) 2003 Mike Frantzen <frantzen@w4g.org>
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.
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.
18 * $OpenBSD: pf_osfp.c,v 1.14 2008/06/12 18:17:01 henning Exp $
21 #include <sys/cdefs.h>
22 __FBSDID("$FreeBSD$");
24 #include "opt_inet6.h"
26 #include <sys/param.h>
27 #include <sys/kernel.h>
30 #include <sys/socket.h>
32 #include <netinet/in.h>
33 #include <netinet/ip.h>
34 #include <netinet/tcp.h>
38 #include <net/pfvar.h>
41 #include <netinet/ip6.h>
44 static MALLOC_DEFINE(M_PFOSFP, "pf_osfp", "pf(4) operating system fingerprints");
45 #define DPFPRINTF(format, x...) \
46 if (V_pf_status.debug >= PF_DEBUG_NOISY) \
49 SLIST_HEAD(pf_osfp_list, pf_os_fingerprint);
50 VNET_DEFINE_STATIC(struct pf_osfp_list, pf_osfp_list) =
51 SLIST_HEAD_INITIALIZER();
52 #define V_pf_osfp_list VNET(pf_osfp_list)
54 static struct pf_osfp_enlist *pf_osfp_fingerprint_hdr(const struct ip *,
55 const struct ip6_hdr *,
56 const struct tcphdr *);
57 static struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *,
58 struct pf_os_fingerprint *, u_int8_t);
59 static struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *,
60 struct pf_os_fingerprint *);
61 static void pf_osfp_insert(struct pf_osfp_list *,
62 struct pf_os_fingerprint *);
64 static struct pf_os_fingerprint *pf_osfp_validate(void);
68 * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
69 * Returns the list of possible OSes.
71 struct pf_osfp_enlist *
72 pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
73 const struct tcphdr *tcp)
79 if ((pd->af != PF_INET && pd->af != PF_INET6) ||
80 pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
83 if (pd->af == PF_INET) {
84 ip = mtod(m, struct ip *);
85 ip6 = (struct ip6_hdr *)NULL;
87 ip = (struct ip *)NULL;
88 ip6 = mtod(m, struct ip6_hdr *);
90 if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
91 pd->af)) return (NULL);
93 return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
96 static struct pf_osfp_enlist *
97 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
99 struct pf_os_fingerprint fp, *fpresult;
101 const u_int8_t *optp;
103 char srcname[INET6_ADDRSTRLEN];
105 char srcname[INET_ADDRSTRLEN];
108 if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
111 if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
115 memset(&fp, 0, sizeof(fp));
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 inet_ntoa_r(ip->ip_src, srcname);
127 fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
128 fp.fp_ttl = ip6->ip6_hlim;
129 fp.fp_flags |= PF_OSFP_DF;
130 fp.fp_flags |= PF_OSFP_INET6;
131 ip6_sprintf(srcname, (const struct in6_addr *)&ip6->ip6_src);
136 fp.fp_wsize = ntohs(tcp->th_win);
139 cnt = (tcp->th_off << 2) - sizeof(*tcp);
140 optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
141 for (; cnt > 0; cnt -= optlen, optp += optlen) {
142 if (*optp == TCPOPT_EOL)
146 if (*optp == TCPOPT_NOP) {
147 fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
154 if (optlen > cnt || optlen < 2)
158 if (optlen >= TCPOLEN_MAXSEG)
159 memcpy(&fp.fp_mss, &optp[2],
161 fp.fp_tcpopts = (fp.fp_tcpopts <<
162 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
166 if (optlen >= TCPOLEN_WINDOW)
167 memcpy(&fp.fp_wscale, &optp[2],
168 sizeof(fp.fp_wscale));
170 fp.fp_tcpopts = (fp.fp_tcpopts <<
171 PF_OSFP_TCPOPT_BITS) |
172 PF_OSFP_TCPOPT_WSCALE;
174 case TCPOPT_SACK_PERMITTED:
175 fp.fp_tcpopts = (fp.fp_tcpopts <<
176 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
178 case TCPOPT_TIMESTAMP:
179 if (optlen >= TCPOLEN_TIMESTAMP) {
181 memcpy(&ts, &optp[2], sizeof(ts));
183 fp.fp_flags |= PF_OSFP_TS0;
186 fp.fp_tcpopts = (fp.fp_tcpopts <<
187 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
193 optlen = MAX(optlen, 1); /* paranoia */
196 DPFPRINTF("fingerprinted %s:%d %d:%d:%d:%d:%llx (%d) "
197 "(TS=%s,M=%s%d,W=%s%d)\n",
198 srcname, ntohs(tcp->th_sport),
199 fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
200 fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
201 (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
202 (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
203 (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
205 (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
206 (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
209 if ((fpresult = pf_osfp_find(&V_pf_osfp_list, &fp,
210 PF_OSFP_MAXTTL_OFFSET)))
211 return (&fpresult->fp_oses);
215 /* Match a fingerprint ID against a list of OSes */
217 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
219 struct pf_osfp_entry *entry;
220 int os_class, os_version, os_subtype;
221 int en_class, en_version, en_subtype;
223 if (os == PF_OSFP_ANY)
226 DPFPRINTF("osfp no match against %x\n", os);
227 return (os == PF_OSFP_UNKNOWN);
229 PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
230 SLIST_FOREACH(entry, list, fp_entry) {
231 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
232 if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
233 (os_version == PF_OSFP_ANY || en_version == os_version) &&
234 (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
235 DPFPRINTF("osfp matched %s %s %s %x==%x\n",
236 entry->fp_class_nm, entry->fp_version_nm,
237 entry->fp_subtype_nm, os, entry->fp_os);
241 DPFPRINTF("fingerprint 0x%x didn't match\n", os);
245 /* Flush the fingerprint list */
249 struct pf_os_fingerprint *fp;
250 struct pf_osfp_entry *entry;
252 while ((fp = SLIST_FIRST(&V_pf_osfp_list))) {
253 SLIST_REMOVE_HEAD(&V_pf_osfp_list, fp_next);
254 while ((entry = SLIST_FIRST(&fp->fp_oses))) {
255 SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
256 free(entry, M_PFOSFP);
263 /* Add a fingerprint */
265 pf_osfp_add(struct pf_osfp_ioctl *fpioc)
267 struct pf_os_fingerprint *fp, fpadd;
268 struct pf_osfp_entry *entry;
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;
282 #if 0 /* XXX RYAN wants to fix logging */
283 DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
284 "(TS=%s,M=%s%d,W=%s%d) %x\n",
285 fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
286 fpioc->fp_os.fp_subtype_nm,
287 (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
288 (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
289 (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
290 (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
293 (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
294 (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
295 (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
297 (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
298 (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
299 (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
300 (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
302 (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
303 (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
308 if ((fp = pf_osfp_find_exact(&V_pf_osfp_list, &fpadd))) {
309 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
310 if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
313 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
317 if ((fp = malloc(sizeof(*fp), M_PFOSFP, M_ZERO | M_NOWAIT))
320 fp->fp_tcpopts = fpioc->fp_tcpopts;
321 fp->fp_wsize = fpioc->fp_wsize;
322 fp->fp_psize = fpioc->fp_psize;
323 fp->fp_mss = fpioc->fp_mss;
324 fp->fp_flags = fpioc->fp_flags;
325 fp->fp_optcnt = fpioc->fp_optcnt;
326 fp->fp_wscale = fpioc->fp_wscale;
327 fp->fp_ttl = fpioc->fp_ttl;
328 SLIST_INIT(&fp->fp_oses);
329 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
334 pf_osfp_insert(&V_pf_osfp_list, fp);
336 memcpy(entry, &fpioc->fp_os, sizeof(*entry));
338 /* Make sure the strings are NUL terminated */
339 entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
340 entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
341 entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
343 SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
346 if ((fp = pf_osfp_validate()))
347 printf("Invalid fingerprint list\n");
353 /* Find a fingerprint in the list */
354 static struct pf_os_fingerprint *
355 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
358 struct pf_os_fingerprint *f;
360 #define MATCH_INT(_MOD, _DC, _field) \
361 if ((f->fp_flags & _DC) == 0) { \
362 if ((f->fp_flags & _MOD) == 0) { \
363 if (f->_field != find->_field) \
366 if (f->_field == 0 || find->_field % f->_field) \
371 SLIST_FOREACH(f, list, fp_next) {
372 if (f->fp_tcpopts != find->fp_tcpopts ||
373 f->fp_optcnt != find->fp_optcnt ||
374 f->fp_ttl < find->fp_ttl ||
375 f->fp_ttl - find->fp_ttl > ttldiff ||
376 (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
377 (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
380 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
381 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
382 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
383 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
384 if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
385 if (find->fp_mss == 0)
389 * Some "smart" NAT devices and DSL routers will tweak the MSS size and
390 * will set it to whatever is suitable for the link type.
392 #define SMART_MSS 1460
393 if ((find->fp_wsize % find->fp_mss ||
394 find->fp_wsize / find->fp_mss !=
396 (find->fp_wsize % SMART_MSS ||
397 find->fp_wsize / SMART_MSS !=
400 } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
401 if (find->fp_mss == 0)
404 #define MTUOFF (sizeof(struct ip) + sizeof(struct tcphdr))
405 #define SMART_MTU (SMART_MSS + MTUOFF)
406 if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
407 find->fp_wsize / (find->fp_mss + MTUOFF) !=
409 (find->fp_wsize % SMART_MTU ||
410 find->fp_wsize / SMART_MTU !=
413 } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
414 if (f->fp_wsize == 0 || find->fp_wsize %
418 if (f->fp_wsize != find->fp_wsize)
428 /* Find an exact fingerprint in the list */
429 static struct pf_os_fingerprint *
430 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
432 struct pf_os_fingerprint *f;
434 SLIST_FOREACH(f, list, fp_next) {
435 if (f->fp_tcpopts == find->fp_tcpopts &&
436 f->fp_wsize == find->fp_wsize &&
437 f->fp_psize == find->fp_psize &&
438 f->fp_mss == find->fp_mss &&
439 f->fp_flags == find->fp_flags &&
440 f->fp_optcnt == find->fp_optcnt &&
441 f->fp_wscale == find->fp_wscale &&
442 f->fp_ttl == find->fp_ttl)
449 /* Insert a fingerprint into the list */
451 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
453 struct pf_os_fingerprint *f, *prev = NULL;
455 /* XXX need to go semi tree based. can key on tcp options */
457 SLIST_FOREACH(f, list, fp_next)
460 SLIST_INSERT_AFTER(prev, ins, fp_next);
462 SLIST_INSERT_HEAD(list, ins, fp_next);
465 /* Fill a fingerprint by its number (from an ioctl) */
467 pf_osfp_get(struct pf_osfp_ioctl *fpioc)
469 struct pf_os_fingerprint *fp;
470 struct pf_osfp_entry *entry;
471 int num = fpioc->fp_getnum;
475 memset(fpioc, 0, sizeof(*fpioc));
476 SLIST_FOREACH(fp, &V_pf_osfp_list, fp_next) {
477 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
479 fpioc->fp_mss = fp->fp_mss;
480 fpioc->fp_wsize = fp->fp_wsize;
481 fpioc->fp_flags = fp->fp_flags;
482 fpioc->fp_psize = fp->fp_psize;
483 fpioc->fp_ttl = fp->fp_ttl;
484 fpioc->fp_wscale = fp->fp_wscale;
485 fpioc->fp_getnum = num;
486 memcpy(&fpioc->fp_os, entry,
487 sizeof(fpioc->fp_os));
498 /* Validate that each signature is reachable */
499 static struct pf_os_fingerprint *
500 pf_osfp_validate(void)
502 struct pf_os_fingerprint *f, *f2, find;
504 SLIST_FOREACH(f, &V_pf_osfp_list, fp_next) {
505 memcpy(&find, f, sizeof(find));
507 /* We do a few MSS/th_win percolations to make things unique */
508 if (find.fp_mss == 0)
510 if (f->fp_flags & PF_OSFP_WSIZE_MSS)
511 find.fp_wsize *= find.fp_mss;
512 else if (f->fp_flags & PF_OSFP_WSIZE_MTU)
513 find.fp_wsize *= (find.fp_mss + 40);
514 else if (f->fp_flags & PF_OSFP_WSIZE_MOD)
516 if (f != (f2 = pf_osfp_find(&V_pf_osfp_list, &find, 0))) {
518 printf("Found \"%s %s %s\" instead of "
520 SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
521 SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
522 SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
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);
527 printf("Couldn't find \"%s %s %s\"\n",
528 SLIST_FIRST(&f->fp_oses)->fp_class_nm,
529 SLIST_FIRST(&f->fp_oses)->fp_version_nm,
530 SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);