1/* $OpenBSD: pf_osfp.c,v 1.14 2008/06/12 18:17:01 henning Exp $ */
2
3/*
4 * Copyright (c) 2003 Mike Frantzen <frantzen@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/cdefs.h>
21__FBSDID("$FreeBSD: head/sys/contrib/pf/net/pf_osfp.c 240233 2012-09-08 06:41:54Z glebius $");
22
23#include <sys/param.h>
24#include <sys/kernel.h>
25#include <sys/socket.h>
26
27#include <netinet/in.h>
28#include <netinet/ip.h>
29#include <netinet/tcp.h>
30
31#include <net/if.h>
32#include <net/pfvar.h>
33
34#include <netinet/ip6.h>
35#include <netinet6/in6_var.h>
36
37static MALLOC_DEFINE(M_PFOSFP, "pf_osfp", "pf(4) operating system fingerprints");
38#define DPFPRINTF(format, x...) \
39 if (V_pf_status.debug >= PF_DEBUG_NOISY) \
40 printf(format , ##x)
41
42SLIST_HEAD(pf_osfp_list, pf_os_fingerprint);
43static VNET_DEFINE(struct pf_osfp_list, pf_osfp_list) =
44 SLIST_HEAD_INITIALIZER();
45#define V_pf_osfp_list VNET(pf_osfp_list)
46
47static struct pf_osfp_enlist *pf_osfp_fingerprint_hdr(const struct ip *,
48 const struct ip6_hdr *,
49 const struct tcphdr *);
50static struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *,
51 struct pf_os_fingerprint *, u_int8_t);
52static struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *,
53 struct pf_os_fingerprint *);
54static void pf_osfp_insert(struct pf_osfp_list *,
55 struct pf_os_fingerprint *);
56#ifdef PFDEBUG
57static struct pf_os_fingerprint *pf_osfp_validate(void);
58#endif
59
60/*
61 * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
62 * Returns the list of possible OSes.
63 */
64struct pf_osfp_enlist *
65pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
66 const struct tcphdr *tcp)
67{
68 struct ip *ip;
69 struct ip6_hdr *ip6;
70 char hdr[60];
71
72 if ((pd->af != PF_INET && pd->af != PF_INET6) ||
73 pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
74 return (NULL);
75
76 if (pd->af == PF_INET) {
77 ip = mtod(m, struct ip *);
78 ip6 = (struct ip6_hdr *)NULL;
79 } else {
80 ip = (struct ip *)NULL;
81 ip6 = mtod(m, struct ip6_hdr *);
82 }
83 if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
84 pd->af)) return (NULL);
85
86 return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
87}
88
89static struct pf_osfp_enlist *
90pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
91{
92 struct pf_os_fingerprint fp, *fpresult;
93 int cnt, optlen = 0;
94 const u_int8_t *optp;
95 char srcname[128];
96
97 if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
98 return (NULL);
99 if (ip) {
100 if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
101 return (NULL);
102 }
103
104 memset(&fp, 0, sizeof(fp));
105
106 if (ip) {
107 fp.fp_psize = ntohs(ip->ip_len);
108 fp.fp_ttl = ip->ip_ttl;
109 if (ip->ip_off & htons(IP_DF))
110 fp.fp_flags |= PF_OSFP_DF;
111 strlcpy(srcname, inet_ntoa(ip->ip_src), sizeof(srcname));
112 }
113#ifdef INET6
114 else if (ip6) {
115 /* jumbo payload? */
116 fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
117 fp.fp_ttl = ip6->ip6_hlim;
118 fp.fp_flags |= PF_OSFP_DF;
119 fp.fp_flags |= PF_OSFP_INET6;
120 strlcpy(srcname, ip6_sprintf((struct in6_addr *)&ip6->ip6_src),
121 sizeof(srcname));
122 }
123#endif
124 else
125 return (NULL);
126 fp.fp_wsize = ntohs(tcp->th_win);
127
128
129 cnt = (tcp->th_off << 2) - sizeof(*tcp);
130 optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
131 for (; cnt > 0; cnt -= optlen, optp += optlen) {
132 if (*optp == TCPOPT_EOL)
133 break;
134
135 fp.fp_optcnt++;
136 if (*optp == TCPOPT_NOP) {
137 fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
138 PF_OSFP_TCPOPT_NOP;
139 optlen = 1;
140 } else {
141 if (cnt < 2)
142 return (NULL);
143 optlen = optp[1];
144 if (optlen > cnt || optlen < 2)
145 return (NULL);
146 switch (*optp) {
147 case TCPOPT_MAXSEG:
148 if (optlen >= TCPOLEN_MAXSEG)
149 memcpy(&fp.fp_mss, &optp[2],
150 sizeof(fp.fp_mss));
151 fp.fp_tcpopts = (fp.fp_tcpopts <<
152 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
153 NTOHS(fp.fp_mss);
154 break;
155 case TCPOPT_WINDOW:
156 if (optlen >= TCPOLEN_WINDOW)
157 memcpy(&fp.fp_wscale, &optp[2],
158 sizeof(fp.fp_wscale));
159 NTOHS(fp.fp_wscale);
160 fp.fp_tcpopts = (fp.fp_tcpopts <<
161 PF_OSFP_TCPOPT_BITS) |
162 PF_OSFP_TCPOPT_WSCALE;
163 break;
164 case TCPOPT_SACK_PERMITTED:
165 fp.fp_tcpopts = (fp.fp_tcpopts <<
166 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
167 break;
168 case TCPOPT_TIMESTAMP:
169 if (optlen >= TCPOLEN_TIMESTAMP) {
170 u_int32_t ts;
171 memcpy(&ts, &optp[2], sizeof(ts));
172 if (ts == 0)
173 fp.fp_flags |= PF_OSFP_TS0;
174
175 }
176 fp.fp_tcpopts = (fp.fp_tcpopts <<
177 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
178 break;
179 default:
180 return (NULL);
181 }
182 }
183 optlen = MAX(optlen, 1); /* paranoia */
184 }
185
186 DPFPRINTF("fingerprinted %s:%d %d:%d:%d:%d:%llx (%d) "
187 "(TS=%s,M=%s%d,W=%s%d)\n",
188 srcname, ntohs(tcp->th_sport),
189 fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
190 fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
191 (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
192 (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
193 (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
194 fp.fp_mss,
195 (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
196 (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
197 fp.fp_wscale);
198
199 if ((fpresult = pf_osfp_find(&V_pf_osfp_list, &fp,
200 PF_OSFP_MAXTTL_OFFSET)))
201 return (&fpresult->fp_oses);
202 return (NULL);
203}
204
205/* Match a fingerprint ID against a list of OSes */
206int
207pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
208{
209 struct pf_osfp_entry *entry;
210 int os_class, os_version, os_subtype;
211 int en_class, en_version, en_subtype;
212
213 if (os == PF_OSFP_ANY)
214 return (1);
215 if (list == NULL) {
216 DPFPRINTF("osfp no match against %x\n", os);
217 return (os == PF_OSFP_UNKNOWN);
218 }
219 PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
220 SLIST_FOREACH(entry, list, fp_entry) {
221 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
222 if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
223 (os_version == PF_OSFP_ANY || en_version == os_version) &&
224 (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
225 DPFPRINTF("osfp matched %s %s %s %x==%x\n",
226 entry->fp_class_nm, entry->fp_version_nm,
227 entry->fp_subtype_nm, os, entry->fp_os);
228 return (1);
229 }
230 }
231 DPFPRINTF("fingerprint 0x%x didn't match\n", os);
232 return (0);
233}
234
235/* Flush the fingerprint list */
236void
237pf_osfp_flush(void)
238{
239 struct pf_os_fingerprint *fp;
240 struct pf_osfp_entry *entry;
241
242 while ((fp = SLIST_FIRST(&V_pf_osfp_list))) {
243 SLIST_REMOVE_HEAD(&V_pf_osfp_list, fp_next);
244 while ((entry = SLIST_FIRST(&fp->fp_oses))) {
245 SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
246 free(entry, M_PFOSFP);
247 }
248 free(fp, M_PFOSFP);
249 }
250}
251
252
253/* Add a fingerprint */
254int
255pf_osfp_add(struct pf_osfp_ioctl *fpioc)
256{
257 struct pf_os_fingerprint *fp, fpadd;
258 struct pf_osfp_entry *entry;
259
260 PF_RULES_WASSERT();
261
262 memset(&fpadd, 0, sizeof(fpadd));
263 fpadd.fp_tcpopts = fpioc->fp_tcpopts;
264 fpadd.fp_wsize = fpioc->fp_wsize;
265 fpadd.fp_psize = fpioc->fp_psize;
266 fpadd.fp_mss = fpioc->fp_mss;
267 fpadd.fp_flags = fpioc->fp_flags;
268 fpadd.fp_optcnt = fpioc->fp_optcnt;
269 fpadd.fp_wscale = fpioc->fp_wscale;
270 fpadd.fp_ttl = fpioc->fp_ttl;
271
272#if 0 /* XXX RYAN wants to fix logging */
273 DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
274 "(TS=%s,M=%s%d,W=%s%d) %x\n",
275 fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
276 fpioc->fp_os.fp_subtype_nm,
277 (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
278 (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
279 (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
280 (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
281 fpadd.fp_wsize,
282 fpadd.fp_ttl,
283 (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
284 (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
285 (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
286 fpadd.fp_psize,
287 (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
288 (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
289 (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
290 (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
291 fpadd.fp_mss,
292 (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
293 (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
294 fpadd.fp_wscale,
295 fpioc->fp_os.fp_os);
296#endif
297
298 if ((fp = pf_osfp_find_exact(&V_pf_osfp_list, &fpadd))) {
299 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
300 if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
301 return (EEXIST);
302 }
303 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
304 == NULL)
305 return (ENOMEM);
306 } else {
307 if ((fp = malloc(sizeof(*fp), M_PFOSFP, M_ZERO | M_NOWAIT))
308 == NULL)
309 return (ENOMEM);
310 fp->fp_tcpopts = fpioc->fp_tcpopts;
311 fp->fp_wsize = fpioc->fp_wsize;
312 fp->fp_psize = fpioc->fp_psize;
313 fp->fp_mss = fpioc->fp_mss;
314 fp->fp_flags = fpioc->fp_flags;
315 fp->fp_optcnt = fpioc->fp_optcnt;
316 fp->fp_wscale = fpioc->fp_wscale;
317 fp->fp_ttl = fpioc->fp_ttl;
318 SLIST_INIT(&fp->fp_oses);
319 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
320 == NULL) {
321 free(fp, M_PFOSFP);
322 return (ENOMEM);
323 }
324 pf_osfp_insert(&V_pf_osfp_list, fp);
325 }
326 memcpy(entry, &fpioc->fp_os, sizeof(*entry));
327
328 /* Make sure the strings are NUL terminated */
329 entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
330 entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
331 entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
332
333 SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
334
335#ifdef PFDEBUG
336 if ((fp = pf_osfp_validate()))
337 printf("Invalid fingerprint list\n");
338#endif /* PFDEBUG */
339 return (0);
340}
341
342
343/* Find a fingerprint in the list */
344static struct pf_os_fingerprint *
345pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
346 u_int8_t ttldiff)
347{
348 struct pf_os_fingerprint *f;
349
350#define MATCH_INT(_MOD, _DC, _field) \
351 if ((f->fp_flags & _DC) == 0) { \
352 if ((f->fp_flags & _MOD) == 0) { \
353 if (f->_field != find->_field) \
354 continue; \
355 } else { \
356 if (f->_field == 0 || find->_field % f->_field) \
357 continue; \
358 } \
359 }
360
361 SLIST_FOREACH(f, list, fp_next) {
362 if (f->fp_tcpopts != find->fp_tcpopts ||
363 f->fp_optcnt != find->fp_optcnt ||
364 f->fp_ttl < find->fp_ttl ||
365 f->fp_ttl - find->fp_ttl > ttldiff ||
366 (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
367 (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
368 continue;
369
370 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
371 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
372 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
373 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
374 if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
375 if (find->fp_mss == 0)
376 continue;
377
378/*
379 * Some "smart" NAT devices and DSL routers will tweak the MSS size and
380 * will set it to whatever is suitable for the link type.
381 */
382#define SMART_MSS 1460
383 if ((find->fp_wsize % find->fp_mss ||
384 find->fp_wsize / find->fp_mss !=
385 f->fp_wsize) &&
386 (find->fp_wsize % SMART_MSS ||
387 find->fp_wsize / SMART_MSS !=
388 f->fp_wsize))
389 continue;
390 } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
391 if (find->fp_mss == 0)
392 continue;
393
394#define MTUOFF (sizeof(struct ip) + sizeof(struct tcphdr))
395#define SMART_MTU (SMART_MSS + MTUOFF)
396 if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
397 find->fp_wsize / (find->fp_mss + MTUOFF) !=
398 f->fp_wsize) &&
399 (find->fp_wsize % SMART_MTU ||
400 find->fp_wsize / SMART_MTU !=
401 f->fp_wsize))
402 continue;
403 } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
404 if (f->fp_wsize == 0 || find->fp_wsize %
405 f->fp_wsize)
406 continue;
407 } else {
408 if (f->fp_wsize != find->fp_wsize)
409 continue;
410 }
411 }
412 return (f);
413 }
414
415 return (NULL);
416}
417
418/* Find an exact fingerprint in the list */
419static struct pf_os_fingerprint *
420pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
421{
422 struct pf_os_fingerprint *f;
423
424 SLIST_FOREACH(f, list, fp_next) {
425 if (f->fp_tcpopts == find->fp_tcpopts &&
426 f->fp_wsize == find->fp_wsize &&
427 f->fp_psize == find->fp_psize &&
428 f->fp_mss == find->fp_mss &&
429 f->fp_flags == find->fp_flags &&
430 f->fp_optcnt == find->fp_optcnt &&
431 f->fp_wscale == find->fp_wscale &&
432 f->fp_ttl == find->fp_ttl)
433 return (f);
434 }
435
436 return (NULL);
437}
438
439/* Insert a fingerprint into the list */
440static void
441pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
442{
443 struct pf_os_fingerprint *f, *prev = NULL;
444
445 /* XXX need to go semi tree based. can key on tcp options */
446
447 SLIST_FOREACH(f, list, fp_next)
448 prev = f;
449 if (prev)
450 SLIST_INSERT_AFTER(prev, ins, fp_next);
451 else
452 SLIST_INSERT_HEAD(list, ins, fp_next);
453}
454
455/* Fill a fingerprint by its number (from an ioctl) */
456int
457pf_osfp_get(struct pf_osfp_ioctl *fpioc)
458{
459 struct pf_os_fingerprint *fp;
460 struct pf_osfp_entry *entry;
461 int num = fpioc->fp_getnum;
462 int i = 0;
463
464
465 memset(fpioc, 0, sizeof(*fpioc));
466 SLIST_FOREACH(fp, &V_pf_osfp_list, fp_next) {
467 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
468 if (i++ == num) {
469 fpioc->fp_mss = fp->fp_mss;
470 fpioc->fp_wsize = fp->fp_wsize;
471 fpioc->fp_flags = fp->fp_flags;
472 fpioc->fp_psize = fp->fp_psize;
473 fpioc->fp_ttl = fp->fp_ttl;
474 fpioc->fp_wscale = fp->fp_wscale;
475 fpioc->fp_getnum = num;
476 memcpy(&fpioc->fp_os, entry,
477 sizeof(fpioc->fp_os));
478 return (0);
479 }
480 }
481 }
482
483 return (EBUSY);
484}
485
486
487#ifdef PFDEBUG
488/* Validate that each signature is reachable */
489static struct pf_os_fingerprint *
490pf_osfp_validate(void)
491{
492 struct pf_os_fingerprint *f, *f2, find;
493
494 SLIST_FOREACH(f, &V_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;
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(&V_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#endif /* PFDEBUG */
2
3/*
4 * Copyright (c) 2003 Mike Frantzen <frantzen@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/cdefs.h>
21__FBSDID("$FreeBSD: head/sys/contrib/pf/net/pf_osfp.c 240233 2012-09-08 06:41:54Z glebius $");
22
23#include <sys/param.h>
24#include <sys/kernel.h>
25#include <sys/socket.h>
26
27#include <netinet/in.h>
28#include <netinet/ip.h>
29#include <netinet/tcp.h>
30
31#include <net/if.h>
32#include <net/pfvar.h>
33
34#include <netinet/ip6.h>
35#include <netinet6/in6_var.h>
36
37static MALLOC_DEFINE(M_PFOSFP, "pf_osfp", "pf(4) operating system fingerprints");
38#define DPFPRINTF(format, x...) \
39 if (V_pf_status.debug >= PF_DEBUG_NOISY) \
40 printf(format , ##x)
41
42SLIST_HEAD(pf_osfp_list, pf_os_fingerprint);
43static VNET_DEFINE(struct pf_osfp_list, pf_osfp_list) =
44 SLIST_HEAD_INITIALIZER();
45#define V_pf_osfp_list VNET(pf_osfp_list)
46
47static struct pf_osfp_enlist *pf_osfp_fingerprint_hdr(const struct ip *,
48 const struct ip6_hdr *,
49 const struct tcphdr *);
50static struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *,
51 struct pf_os_fingerprint *, u_int8_t);
52static struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *,
53 struct pf_os_fingerprint *);
54static void pf_osfp_insert(struct pf_osfp_list *,
55 struct pf_os_fingerprint *);
56#ifdef PFDEBUG
57static struct pf_os_fingerprint *pf_osfp_validate(void);
58#endif
59
60/*
61 * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
62 * Returns the list of possible OSes.
63 */
64struct pf_osfp_enlist *
65pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
66 const struct tcphdr *tcp)
67{
68 struct ip *ip;
69 struct ip6_hdr *ip6;
70 char hdr[60];
71
72 if ((pd->af != PF_INET && pd->af != PF_INET6) ||
73 pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
74 return (NULL);
75
76 if (pd->af == PF_INET) {
77 ip = mtod(m, struct ip *);
78 ip6 = (struct ip6_hdr *)NULL;
79 } else {
80 ip = (struct ip *)NULL;
81 ip6 = mtod(m, struct ip6_hdr *);
82 }
83 if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
84 pd->af)) return (NULL);
85
86 return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
87}
88
89static struct pf_osfp_enlist *
90pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
91{
92 struct pf_os_fingerprint fp, *fpresult;
93 int cnt, optlen = 0;
94 const u_int8_t *optp;
95 char srcname[128];
96
97 if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
98 return (NULL);
99 if (ip) {
100 if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
101 return (NULL);
102 }
103
104 memset(&fp, 0, sizeof(fp));
105
106 if (ip) {
107 fp.fp_psize = ntohs(ip->ip_len);
108 fp.fp_ttl = ip->ip_ttl;
109 if (ip->ip_off & htons(IP_DF))
110 fp.fp_flags |= PF_OSFP_DF;
111 strlcpy(srcname, inet_ntoa(ip->ip_src), sizeof(srcname));
112 }
113#ifdef INET6
114 else if (ip6) {
115 /* jumbo payload? */
116 fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
117 fp.fp_ttl = ip6->ip6_hlim;
118 fp.fp_flags |= PF_OSFP_DF;
119 fp.fp_flags |= PF_OSFP_INET6;
120 strlcpy(srcname, ip6_sprintf((struct in6_addr *)&ip6->ip6_src),
121 sizeof(srcname));
122 }
123#endif
124 else
125 return (NULL);
126 fp.fp_wsize = ntohs(tcp->th_win);
127
128
129 cnt = (tcp->th_off << 2) - sizeof(*tcp);
130 optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
131 for (; cnt > 0; cnt -= optlen, optp += optlen) {
132 if (*optp == TCPOPT_EOL)
133 break;
134
135 fp.fp_optcnt++;
136 if (*optp == TCPOPT_NOP) {
137 fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
138 PF_OSFP_TCPOPT_NOP;
139 optlen = 1;
140 } else {
141 if (cnt < 2)
142 return (NULL);
143 optlen = optp[1];
144 if (optlen > cnt || optlen < 2)
145 return (NULL);
146 switch (*optp) {
147 case TCPOPT_MAXSEG:
148 if (optlen >= TCPOLEN_MAXSEG)
149 memcpy(&fp.fp_mss, &optp[2],
150 sizeof(fp.fp_mss));
151 fp.fp_tcpopts = (fp.fp_tcpopts <<
152 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
153 NTOHS(fp.fp_mss);
154 break;
155 case TCPOPT_WINDOW:
156 if (optlen >= TCPOLEN_WINDOW)
157 memcpy(&fp.fp_wscale, &optp[2],
158 sizeof(fp.fp_wscale));
159 NTOHS(fp.fp_wscale);
160 fp.fp_tcpopts = (fp.fp_tcpopts <<
161 PF_OSFP_TCPOPT_BITS) |
162 PF_OSFP_TCPOPT_WSCALE;
163 break;
164 case TCPOPT_SACK_PERMITTED:
165 fp.fp_tcpopts = (fp.fp_tcpopts <<
166 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
167 break;
168 case TCPOPT_TIMESTAMP:
169 if (optlen >= TCPOLEN_TIMESTAMP) {
170 u_int32_t ts;
171 memcpy(&ts, &optp[2], sizeof(ts));
172 if (ts == 0)
173 fp.fp_flags |= PF_OSFP_TS0;
174
175 }
176 fp.fp_tcpopts = (fp.fp_tcpopts <<
177 PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
178 break;
179 default:
180 return (NULL);
181 }
182 }
183 optlen = MAX(optlen, 1); /* paranoia */
184 }
185
186 DPFPRINTF("fingerprinted %s:%d %d:%d:%d:%d:%llx (%d) "
187 "(TS=%s,M=%s%d,W=%s%d)\n",
188 srcname, ntohs(tcp->th_sport),
189 fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
190 fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
191 (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
192 (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
193 (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
194 fp.fp_mss,
195 (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
196 (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
197 fp.fp_wscale);
198
199 if ((fpresult = pf_osfp_find(&V_pf_osfp_list, &fp,
200 PF_OSFP_MAXTTL_OFFSET)))
201 return (&fpresult->fp_oses);
202 return (NULL);
203}
204
205/* Match a fingerprint ID against a list of OSes */
206int
207pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
208{
209 struct pf_osfp_entry *entry;
210 int os_class, os_version, os_subtype;
211 int en_class, en_version, en_subtype;
212
213 if (os == PF_OSFP_ANY)
214 return (1);
215 if (list == NULL) {
216 DPFPRINTF("osfp no match against %x\n", os);
217 return (os == PF_OSFP_UNKNOWN);
218 }
219 PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
220 SLIST_FOREACH(entry, list, fp_entry) {
221 PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
222 if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
223 (os_version == PF_OSFP_ANY || en_version == os_version) &&
224 (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
225 DPFPRINTF("osfp matched %s %s %s %x==%x\n",
226 entry->fp_class_nm, entry->fp_version_nm,
227 entry->fp_subtype_nm, os, entry->fp_os);
228 return (1);
229 }
230 }
231 DPFPRINTF("fingerprint 0x%x didn't match\n", os);
232 return (0);
233}
234
235/* Flush the fingerprint list */
236void
237pf_osfp_flush(void)
238{
239 struct pf_os_fingerprint *fp;
240 struct pf_osfp_entry *entry;
241
242 while ((fp = SLIST_FIRST(&V_pf_osfp_list))) {
243 SLIST_REMOVE_HEAD(&V_pf_osfp_list, fp_next);
244 while ((entry = SLIST_FIRST(&fp->fp_oses))) {
245 SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
246 free(entry, M_PFOSFP);
247 }
248 free(fp, M_PFOSFP);
249 }
250}
251
252
253/* Add a fingerprint */
254int
255pf_osfp_add(struct pf_osfp_ioctl *fpioc)
256{
257 struct pf_os_fingerprint *fp, fpadd;
258 struct pf_osfp_entry *entry;
259
260 PF_RULES_WASSERT();
261
262 memset(&fpadd, 0, sizeof(fpadd));
263 fpadd.fp_tcpopts = fpioc->fp_tcpopts;
264 fpadd.fp_wsize = fpioc->fp_wsize;
265 fpadd.fp_psize = fpioc->fp_psize;
266 fpadd.fp_mss = fpioc->fp_mss;
267 fpadd.fp_flags = fpioc->fp_flags;
268 fpadd.fp_optcnt = fpioc->fp_optcnt;
269 fpadd.fp_wscale = fpioc->fp_wscale;
270 fpadd.fp_ttl = fpioc->fp_ttl;
271
272#if 0 /* XXX RYAN wants to fix logging */
273 DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
274 "(TS=%s,M=%s%d,W=%s%d) %x\n",
275 fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
276 fpioc->fp_os.fp_subtype_nm,
277 (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
278 (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
279 (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
280 (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
281 fpadd.fp_wsize,
282 fpadd.fp_ttl,
283 (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
284 (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
285 (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
286 fpadd.fp_psize,
287 (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
288 (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
289 (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
290 (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
291 fpadd.fp_mss,
292 (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
293 (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
294 fpadd.fp_wscale,
295 fpioc->fp_os.fp_os);
296#endif
297
298 if ((fp = pf_osfp_find_exact(&V_pf_osfp_list, &fpadd))) {
299 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
300 if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
301 return (EEXIST);
302 }
303 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
304 == NULL)
305 return (ENOMEM);
306 } else {
307 if ((fp = malloc(sizeof(*fp), M_PFOSFP, M_ZERO | M_NOWAIT))
308 == NULL)
309 return (ENOMEM);
310 fp->fp_tcpopts = fpioc->fp_tcpopts;
311 fp->fp_wsize = fpioc->fp_wsize;
312 fp->fp_psize = fpioc->fp_psize;
313 fp->fp_mss = fpioc->fp_mss;
314 fp->fp_flags = fpioc->fp_flags;
315 fp->fp_optcnt = fpioc->fp_optcnt;
316 fp->fp_wscale = fpioc->fp_wscale;
317 fp->fp_ttl = fpioc->fp_ttl;
318 SLIST_INIT(&fp->fp_oses);
319 if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
320 == NULL) {
321 free(fp, M_PFOSFP);
322 return (ENOMEM);
323 }
324 pf_osfp_insert(&V_pf_osfp_list, fp);
325 }
326 memcpy(entry, &fpioc->fp_os, sizeof(*entry));
327
328 /* Make sure the strings are NUL terminated */
329 entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
330 entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
331 entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
332
333 SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
334
335#ifdef PFDEBUG
336 if ((fp = pf_osfp_validate()))
337 printf("Invalid fingerprint list\n");
338#endif /* PFDEBUG */
339 return (0);
340}
341
342
343/* Find a fingerprint in the list */
344static struct pf_os_fingerprint *
345pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
346 u_int8_t ttldiff)
347{
348 struct pf_os_fingerprint *f;
349
350#define MATCH_INT(_MOD, _DC, _field) \
351 if ((f->fp_flags & _DC) == 0) { \
352 if ((f->fp_flags & _MOD) == 0) { \
353 if (f->_field != find->_field) \
354 continue; \
355 } else { \
356 if (f->_field == 0 || find->_field % f->_field) \
357 continue; \
358 } \
359 }
360
361 SLIST_FOREACH(f, list, fp_next) {
362 if (f->fp_tcpopts != find->fp_tcpopts ||
363 f->fp_optcnt != find->fp_optcnt ||
364 f->fp_ttl < find->fp_ttl ||
365 f->fp_ttl - find->fp_ttl > ttldiff ||
366 (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
367 (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
368 continue;
369
370 MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
371 MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
372 MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
373 if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
374 if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
375 if (find->fp_mss == 0)
376 continue;
377
378/*
379 * Some "smart" NAT devices and DSL routers will tweak the MSS size and
380 * will set it to whatever is suitable for the link type.
381 */
382#define SMART_MSS 1460
383 if ((find->fp_wsize % find->fp_mss ||
384 find->fp_wsize / find->fp_mss !=
385 f->fp_wsize) &&
386 (find->fp_wsize % SMART_MSS ||
387 find->fp_wsize / SMART_MSS !=
388 f->fp_wsize))
389 continue;
390 } else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
391 if (find->fp_mss == 0)
392 continue;
393
394#define MTUOFF (sizeof(struct ip) + sizeof(struct tcphdr))
395#define SMART_MTU (SMART_MSS + MTUOFF)
396 if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
397 find->fp_wsize / (find->fp_mss + MTUOFF) !=
398 f->fp_wsize) &&
399 (find->fp_wsize % SMART_MTU ||
400 find->fp_wsize / SMART_MTU !=
401 f->fp_wsize))
402 continue;
403 } else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
404 if (f->fp_wsize == 0 || find->fp_wsize %
405 f->fp_wsize)
406 continue;
407 } else {
408 if (f->fp_wsize != find->fp_wsize)
409 continue;
410 }
411 }
412 return (f);
413 }
414
415 return (NULL);
416}
417
418/* Find an exact fingerprint in the list */
419static struct pf_os_fingerprint *
420pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
421{
422 struct pf_os_fingerprint *f;
423
424 SLIST_FOREACH(f, list, fp_next) {
425 if (f->fp_tcpopts == find->fp_tcpopts &&
426 f->fp_wsize == find->fp_wsize &&
427 f->fp_psize == find->fp_psize &&
428 f->fp_mss == find->fp_mss &&
429 f->fp_flags == find->fp_flags &&
430 f->fp_optcnt == find->fp_optcnt &&
431 f->fp_wscale == find->fp_wscale &&
432 f->fp_ttl == find->fp_ttl)
433 return (f);
434 }
435
436 return (NULL);
437}
438
439/* Insert a fingerprint into the list */
440static void
441pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
442{
443 struct pf_os_fingerprint *f, *prev = NULL;
444
445 /* XXX need to go semi tree based. can key on tcp options */
446
447 SLIST_FOREACH(f, list, fp_next)
448 prev = f;
449 if (prev)
450 SLIST_INSERT_AFTER(prev, ins, fp_next);
451 else
452 SLIST_INSERT_HEAD(list, ins, fp_next);
453}
454
455/* Fill a fingerprint by its number (from an ioctl) */
456int
457pf_osfp_get(struct pf_osfp_ioctl *fpioc)
458{
459 struct pf_os_fingerprint *fp;
460 struct pf_osfp_entry *entry;
461 int num = fpioc->fp_getnum;
462 int i = 0;
463
464
465 memset(fpioc, 0, sizeof(*fpioc));
466 SLIST_FOREACH(fp, &V_pf_osfp_list, fp_next) {
467 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
468 if (i++ == num) {
469 fpioc->fp_mss = fp->fp_mss;
470 fpioc->fp_wsize = fp->fp_wsize;
471 fpioc->fp_flags = fp->fp_flags;
472 fpioc->fp_psize = fp->fp_psize;
473 fpioc->fp_ttl = fp->fp_ttl;
474 fpioc->fp_wscale = fp->fp_wscale;
475 fpioc->fp_getnum = num;
476 memcpy(&fpioc->fp_os, entry,
477 sizeof(fpioc->fp_os));
478 return (0);
479 }
480 }
481 }
482
483 return (EBUSY);
484}
485
486
487#ifdef PFDEBUG
488/* Validate that each signature is reachable */
489static struct pf_os_fingerprint *
490pf_osfp_validate(void)
491{
492 struct pf_os_fingerprint *f, *f2, find;
493
494 SLIST_FOREACH(f, &V_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;
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(&V_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#endif /* PFDEBUG */