2 * Copyright (c) 2003 Mike Frantzen <frantzen@w4g.org>
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 * $OpenBSD: pf_osfp.c,v 1.14 2008/06/12 18:17:01 henning Exp $
19 #include <sys/cdefs.h>
20 __FBSDID("$FreeBSD$");
22 #include "opt_inet6.h"
24 #include <sys/param.h>
25 #include <sys/kernel.h>
28 #include <sys/rwlock.h>
29 #include <sys/socket.h>
31 #include <netinet/in.h>
32 #include <netinet/ip.h>
33 #include <netinet/tcp.h>
37 #include <net/pfvar.h>
40 #include <netinet/ip6.h>
43 static MALLOC_DEFINE(M_PFOSFP, "pf_osfp", "pf(4) operating system fingerprints");
44 #define DPFPRINTF(format, x...) \
45 if (V_pf_status.debug >= PF_DEBUG_NOISY) \
48 SLIST_HEAD(pf_osfp_list, pf_os_fingerprint);
49 static VNET_DEFINE(struct pf_osfp_list, pf_osfp_list) =
50 SLIST_HEAD_INITIALIZER();
51 #define V_pf_osfp_list VNET(pf_osfp_list)
53 static struct pf_osfp_enlist *pf_osfp_fingerprint_hdr(const struct ip *,
54 const struct ip6_hdr *,
55 const struct tcphdr *);
56 static struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *,
57 struct pf_os_fingerprint *, u_int8_t);
58 static struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *,
59 struct pf_os_fingerprint *);
60 static void pf_osfp_insert(struct pf_osfp_list *,
61 struct pf_os_fingerprint *);
63 static struct pf_os_fingerprint *pf_osfp_validate(void);
67 * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
68 * Returns the list of possible OSes.
70 struct pf_osfp_enlist *
71 pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
72 const struct tcphdr *tcp)
78 if ((pd->af != PF_INET && pd->af != PF_INET6) ||
79 pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
82 if (pd->af == PF_INET) {
83 ip = mtod(m, struct ip *);
84 ip6 = (struct ip6_hdr *)NULL;
86 ip = (struct ip *)NULL;
87 ip6 = mtod(m, struct ip6_hdr *);
89 if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
90 pd->af)) return (NULL);
92 return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
95 static struct pf_osfp_enlist *
96 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
98 struct pf_os_fingerprint fp, *fpresult;
100 const u_int8_t *optp;
102 char srcname[INET6_ADDRSTRLEN];
104 char srcname[INET_ADDRSTRLEN];
107 if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
110 if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
114 memset(&fp, 0, sizeof(fp));
117 fp.fp_psize = ntohs(ip->ip_len);
118 fp.fp_ttl = ip->ip_ttl;
119 if (ip->ip_off & htons(IP_DF))
120 fp.fp_flags |= PF_OSFP_DF;
121 inet_ntoa_r(ip->ip_src, srcname);
126 fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
127 fp.fp_ttl = ip6->ip6_hlim;
128 fp.fp_flags |= PF_OSFP_DF;
129 fp.fp_flags |= PF_OSFP_INET6;
130 ip6_sprintf(srcname, (const struct in6_addr *)&ip6->ip6_src);
135 fp.fp_wsize = ntohs(tcp->th_win);
138 cnt = (tcp->th_off << 2) - sizeof(*tcp);
139 optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
140 for (; cnt > 0; cnt -= optlen, optp += optlen) {
141 if (*optp == TCPOPT_EOL)
145 if (*optp == TCPOPT_NOP) {
146 fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
153 if (optlen > cnt || optlen < 2)
157 if (optlen >= TCPOLEN_MAXSEG)
158 memcpy(&fp.fp_mss, &optp[2],
160 fp.fp_tcpopts = (fp.fp_tcpopts <<
161 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
165 if (optlen >= TCPOLEN_WINDOW)
166 memcpy(&fp.fp_wscale, &optp[2],
167 sizeof(fp.fp_wscale));
169 fp.fp_tcpopts = (fp.fp_tcpopts <<
170 PF_OSFP_TCPOPT_BITS) |
171 PF_OSFP_TCPOPT_WSCALE;
173 case TCPOPT_SACK_PERMITTED:
174 fp.fp_tcpopts = (fp.fp_tcpopts <<
175 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
177 case TCPOPT_TIMESTAMP:
178 if (optlen >= TCPOLEN_TIMESTAMP) {
180 memcpy(&ts, &optp[2], sizeof(ts));
182 fp.fp_flags |= PF_OSFP_TS0;
185 fp.fp_tcpopts = (fp.fp_tcpopts <<
186 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
192 optlen = MAX(optlen, 1); /* paranoia */
195 DPFPRINTF("fingerprinted %s:%d %d:%d:%d:%d:%llx (%d) "
196 "(TS=%s,M=%s%d,W=%s%d)\n",
197 srcname, ntohs(tcp->th_sport),
198 fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
199 fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
200 (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
201 (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
202 (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
204 (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
205 (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
208 if ((fpresult = pf_osfp_find(&V_pf_osfp_list, &fp,
209 PF_OSFP_MAXTTL_OFFSET)))
210 return (&fpresult->fp_oses);
214 /* Match a fingerprint ID against a list of OSes */
216 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
218 struct pf_osfp_entry *entry;
219 int os_class, os_version, os_subtype;
220 int en_class, en_version, en_subtype;
222 if (os == PF_OSFP_ANY)
225 DPFPRINTF("osfp no match against %x\n", os);
226 return (os == PF_OSFP_UNKNOWN);
228 PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
229 SLIST_FOREACH(entry, list, fp_entry) {
230 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
231 if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
232 (os_version == PF_OSFP_ANY || en_version == os_version) &&
233 (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
234 DPFPRINTF("osfp matched %s %s %s %x==%x\n",
235 entry->fp_class_nm, entry->fp_version_nm,
236 entry->fp_subtype_nm, os, entry->fp_os);
240 DPFPRINTF("fingerprint 0x%x didn't match\n", os);
244 /* Flush the fingerprint list */
248 struct pf_os_fingerprint *fp;
249 struct pf_osfp_entry *entry;
251 while ((fp = SLIST_FIRST(&V_pf_osfp_list))) {
252 SLIST_REMOVE_HEAD(&V_pf_osfp_list, fp_next);
253 while ((entry = SLIST_FIRST(&fp->fp_oses))) {
254 SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
255 free(entry, M_PFOSFP);
262 /* Add a fingerprint */
264 pf_osfp_add(struct pf_osfp_ioctl *fpioc)
266 struct pf_os_fingerprint *fp, fpadd;
267 struct pf_osfp_entry *entry;
271 memset(&fpadd, 0, sizeof(fpadd));
272 fpadd.fp_tcpopts = fpioc->fp_tcpopts;
273 fpadd.fp_wsize = fpioc->fp_wsize;
274 fpadd.fp_psize = fpioc->fp_psize;
275 fpadd.fp_mss = fpioc->fp_mss;
276 fpadd.fp_flags = fpioc->fp_flags;
277 fpadd.fp_optcnt = fpioc->fp_optcnt;
278 fpadd.fp_wscale = fpioc->fp_wscale;
279 fpadd.fp_ttl = fpioc->fp_ttl;
281 #if 0 /* XXX RYAN wants to fix logging */
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) ? "*" : "",
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) ? "*" : "",
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) ? "*" : "",
301 (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
302 (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
307 if ((fp = pf_osfp_find_exact(&V_pf_osfp_list, &fpadd))) {
308 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
309 if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
312 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
316 if ((fp = malloc(sizeof(*fp), M_PFOSFP, M_ZERO | M_NOWAIT))
319 fp->fp_tcpopts = fpioc->fp_tcpopts;
320 fp->fp_wsize = fpioc->fp_wsize;
321 fp->fp_psize = fpioc->fp_psize;
322 fp->fp_mss = fpioc->fp_mss;
323 fp->fp_flags = fpioc->fp_flags;
324 fp->fp_optcnt = fpioc->fp_optcnt;
325 fp->fp_wscale = fpioc->fp_wscale;
326 fp->fp_ttl = fpioc->fp_ttl;
327 SLIST_INIT(&fp->fp_oses);
328 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
333 pf_osfp_insert(&V_pf_osfp_list, fp);
335 memcpy(entry, &fpioc->fp_os, sizeof(*entry));
337 /* Make sure the strings are NUL terminated */
338 entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
339 entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
340 entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
342 SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
345 if ((fp = pf_osfp_validate()))
346 printf("Invalid fingerprint list\n");
352 /* Find a fingerprint in the list */
353 static struct pf_os_fingerprint *
354 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
357 struct pf_os_fingerprint *f;
359 #define MATCH_INT(_MOD, _DC, _field) \
360 if ((f->fp_flags & _DC) == 0) { \
361 if ((f->fp_flags & _MOD) == 0) { \
362 if (f->_field != find->_field) \
365 if (f->_field == 0 || find->_field % f->_field) \
370 SLIST_FOREACH(f, list, fp_next) {
371 if (f->fp_tcpopts != find->fp_tcpopts ||
372 f->fp_optcnt != find->fp_optcnt ||
373 f->fp_ttl < find->fp_ttl ||
374 f->fp_ttl - find->fp_ttl > ttldiff ||
375 (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
376 (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
379 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
380 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
381 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
382 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
383 if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
384 if (find->fp_mss == 0)
388 * Some "smart" NAT devices and DSL routers will tweak the MSS size and
389 * will set it to whatever is suitable for the link type.
391 #define SMART_MSS 1460
392 if ((find->fp_wsize % find->fp_mss ||
393 find->fp_wsize / find->fp_mss !=
395 (find->fp_wsize % SMART_MSS ||
396 find->fp_wsize / SMART_MSS !=
399 } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
400 if (find->fp_mss == 0)
403 #define MTUOFF (sizeof(struct ip) + sizeof(struct tcphdr))
404 #define SMART_MTU (SMART_MSS + MTUOFF)
405 if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
406 find->fp_wsize / (find->fp_mss + MTUOFF) !=
408 (find->fp_wsize % SMART_MTU ||
409 find->fp_wsize / SMART_MTU !=
412 } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
413 if (f->fp_wsize == 0 || find->fp_wsize %
417 if (f->fp_wsize != find->fp_wsize)
427 /* Find an exact fingerprint in the list */
428 static struct pf_os_fingerprint *
429 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
431 struct pf_os_fingerprint *f;
433 SLIST_FOREACH(f, list, fp_next) {
434 if (f->fp_tcpopts == find->fp_tcpopts &&
435 f->fp_wsize == find->fp_wsize &&
436 f->fp_psize == find->fp_psize &&
437 f->fp_mss == find->fp_mss &&
438 f->fp_flags == find->fp_flags &&
439 f->fp_optcnt == find->fp_optcnt &&
440 f->fp_wscale == find->fp_wscale &&
441 f->fp_ttl == find->fp_ttl)
448 /* Insert a fingerprint into the list */
450 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
452 struct pf_os_fingerprint *f, *prev = NULL;
454 /* XXX need to go semi tree based. can key on tcp options */
456 SLIST_FOREACH(f, list, fp_next)
459 SLIST_INSERT_AFTER(prev, ins, fp_next);
461 SLIST_INSERT_HEAD(list, ins, fp_next);
464 /* Fill a fingerprint by its number (from an ioctl) */
466 pf_osfp_get(struct pf_osfp_ioctl *fpioc)
468 struct pf_os_fingerprint *fp;
469 struct pf_osfp_entry *entry;
470 int num = fpioc->fp_getnum;
474 memset(fpioc, 0, sizeof(*fpioc));
475 SLIST_FOREACH(fp, &V_pf_osfp_list, fp_next) {
476 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
478 fpioc->fp_mss = fp->fp_mss;
479 fpioc->fp_wsize = fp->fp_wsize;
480 fpioc->fp_flags = fp->fp_flags;
481 fpioc->fp_psize = fp->fp_psize;
482 fpioc->fp_ttl = fp->fp_ttl;
483 fpioc->fp_wscale = fp->fp_wscale;
484 fpioc->fp_getnum = num;
485 memcpy(&fpioc->fp_os, entry,
486 sizeof(fpioc->fp_os));
497 /* Validate that each signature is reachable */
498 static struct pf_os_fingerprint *
499 pf_osfp_validate(void)
501 struct pf_os_fingerprint *f, *f2, find;
503 SLIST_FOREACH(f, &V_pf_osfp_list, fp_next) {
504 memcpy(&find, f, sizeof(find));
506 /* We do a few MSS/th_win percolations to make things unique */
507 if (find.fp_mss == 0)
509 if (f->fp_flags & PF_OSFP_WSIZE_MSS)
510 find.fp_wsize *= find.fp_mss;
511 else if (f->fp_flags & PF_OSFP_WSIZE_MTU)
512 find.fp_wsize *= (find.fp_mss + 40);
513 else if (f->fp_flags & PF_OSFP_WSIZE_MOD)
515 if (f != (f2 = pf_osfp_find(&V_pf_osfp_list, &find, 0))) {
517 printf("Found \"%s %s %s\" instead of "
519 SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
520 SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
521 SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
522 SLIST_FIRST(&f->fp_oses)->fp_class_nm,
523 SLIST_FIRST(&f->fp_oses)->fp_version_nm,
524 SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
526 printf("Couldn't find \"%s %s %s\"\n",
527 SLIST_FIRST(&f->fp_oses)->fp_class_nm,
528 SLIST_FIRST(&f->fp_oses)->fp_version_nm,
529 SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);