xref: /dragonfly/sys/net/pf/pf_osfp.c (revision 9348a738)
1 /*	$OpenBSD: pf_osfp.c,v 1.15 2008/06/14 02:22:13 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/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/pf/pfvar.h>
34 
35 #include <netinet/ip6.h>
36 #ifdef _KERNEL
37 #include <netinet6/in6_var.h>
38 #endif
39 
40 
41 #ifdef _KERNEL
42 # define DPFPRINTF(format, x...)		\
43 	if (pf_status.debug >= PF_DEBUG_NOISY)	\
44 		kprintf(format , ##x)
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 # include <netdb.h>
55 
56 # ifdef PFDEBUG
57 #  include <sys/stdarg.h>
58 #  define DPFPRINTF(format, x...)	fprintf(stderr, format , ##x)
59 # else
60 #  define DPFPRINTF(format, x...)	((void)0)
61 # endif /* PFDEBUG */
62 #endif /* _KERNEL */
63 
64 static MALLOC_DEFINE(M_PFOSFPENTRYPL, "pfospfen", "pf OS finger printing pool list");
65 static MALLOC_DEFINE(M_PFOSFPPL, "pfosfp", "pf OS finger printing pool list");
66 
67 SLIST_HEAD(pf_osfp_list, pf_os_fingerprint) pf_osfp_list;
68 
69 struct pf_os_fingerprint	*pf_osfp_find(struct pf_osfp_list *,
70 				    struct pf_os_fingerprint *, u_int8_t);
71 struct pf_os_fingerprint	*pf_osfp_find_exact(struct pf_osfp_list *,
72 				    struct pf_os_fingerprint *);
73 void				 pf_osfp_insert(struct pf_osfp_list *,
74 				    struct pf_os_fingerprint *);
75 
76 
77 #ifdef _KERNEL
78 /*
79  * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
80  * Returns the list of possible OSes.
81  */
82 struct pf_osfp_enlist *
83 pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
84     const struct tcphdr *tcp)
85 {
86 	struct ip *ip;
87 	struct ip6_hdr *ip6;
88 	char hdr[60];
89 
90 	if ((pd->af != PF_INET && pd->af != PF_INET6) ||
91 	    pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
92 		return (NULL);
93 
94 	if (pd->af == PF_INET) {
95 		ip = mtod(m, struct ip *);
96 		ip6 = NULL;
97 	} else {
98 		ip = NULL;
99 		ip6 = mtod(m, struct ip6_hdr *);
100 	}
101 	if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
102 	    pd->af)) return (NULL);
103 
104 	return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
105 }
106 #endif /* _KERNEL */
107 
108 struct pf_osfp_enlist *
109 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
110 {
111 	struct pf_os_fingerprint fp, *fpresult;
112 	int cnt, optlen = 0;
113 	const u_int8_t *optp;
114 #ifdef _KERNEL
115 	char srcname[128];
116 #else
117 	char srcname[NI_MAXHOST];
118 #endif
119 
120 	if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
121 		return (NULL);
122 	if (ip) {
123 		if ((ip->ip_off & IP_OFFMASK) != 0)
124 			return (NULL);
125 	}
126 
127 	memset(&fp, 0, sizeof(fp));
128 
129 	if (ip) {
130 #ifndef _KERNEL
131 		struct sockaddr_in sin;
132 #endif
133 
134 		fp.fp_psize = ip->ip_len;
135 		fp.fp_ttl = ip->ip_ttl;
136 		if (ip->ip_off & IP_DF)
137 			fp.fp_flags |= PF_OSFP_DF;
138 #ifdef _KERNEL
139 		kinet_ntoa(ip->ip_src, srcname);
140 #else
141 		memset(&sin, 0, sizeof(sin));
142 		sin.sin_family = AF_INET;
143 		sin.sin_len = sizeof(struct sockaddr_in);
144 		sin.sin_addr = ip->ip_src;
145 		(void)getnameinfo((struct sockaddr *)&sin,
146 		    sizeof(struct sockaddr_in), srcname, sizeof(srcname),
147 		    NULL, 0, NI_NUMERICHOST);
148 #endif
149 	}
150 #ifdef INET6
151 	else if (ip6) {
152 #ifndef _KERNEL
153 		struct sockaddr_in6 sin6;
154 #endif
155 
156 		/* jumbo payload? */
157 		fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
158 		fp.fp_ttl = ip6->ip6_hlim;
159 		fp.fp_flags |= PF_OSFP_DF;
160 		fp.fp_flags |= PF_OSFP_INET6;
161 #ifdef _KERNEL
162 		strlcpy(srcname, ip6_sprintf((struct in6_addr *)&ip6->ip6_src),
163 		    sizeof(srcname));
164 #else
165 		memset(&sin6, 0, sizeof(sin6));
166 		sin6.sin6_family = AF_INET6;
167 		sin6.sin6_len = sizeof(struct sockaddr_in6);
168 		sin6.sin6_addr = ip6->ip6_src;
169 		(void)getnameinfo((struct sockaddr *)&sin6,
170 		    sizeof(struct sockaddr_in6), srcname, sizeof(srcname),
171 		    NULL, 0, NI_NUMERICHOST);
172 #endif
173 	}
174 #endif
175 	else
176 		return (NULL);
177 	fp.fp_wsize = ntohs(tcp->th_win);
178 
179 
180 	cnt = (tcp->th_off << 2) - sizeof(*tcp);
181 	optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
182 	for (; cnt > 0; cnt -= optlen, optp += optlen) {
183 		if (*optp == TCPOPT_EOL)
184 			break;
185 
186 		fp.fp_optcnt++;
187 		if (*optp == TCPOPT_NOP) {
188 			fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
189 			    PF_OSFP_TCPOPT_NOP;
190 			optlen = 1;
191 		} else {
192 			if (cnt < 2)
193 				return (NULL);
194 			optlen = optp[1];
195 			if (optlen > cnt || optlen < 2)
196 				return (NULL);
197 			switch (*optp) {
198 			case TCPOPT_MAXSEG:
199 				if (optlen >= TCPOLEN_MAXSEG)
200 					memcpy(&fp.fp_mss, &optp[2],
201 					    sizeof(fp.fp_mss));
202 				fp.fp_tcpopts = (fp.fp_tcpopts <<
203 				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
204 				fp.fp_mss = ntohs(fp.fp_mss);
205 				break;
206 			case TCPOPT_WINDOW:
207 				if (optlen >= TCPOLEN_WINDOW)
208 					memcpy(&fp.fp_wscale, &optp[2],
209 					    sizeof(fp.fp_wscale));
210 				fp.fp_tcpopts = (fp.fp_tcpopts <<
211 				    PF_OSFP_TCPOPT_BITS) |
212 				    PF_OSFP_TCPOPT_WSCALE;
213 				break;
214 			case TCPOPT_SACK_PERMITTED:
215 				fp.fp_tcpopts = (fp.fp_tcpopts <<
216 				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
217 				break;
218 			case TCPOPT_TIMESTAMP:
219 				if (optlen >= TCPOLEN_TIMESTAMP) {
220 					u_int32_t ts;
221 					memcpy(&ts, &optp[2], sizeof(ts));
222 					if (ts == 0)
223 						fp.fp_flags |= PF_OSFP_TS0;
224 
225 				}
226 				fp.fp_tcpopts = (fp.fp_tcpopts <<
227 				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
228 				break;
229 			default:
230 				return (NULL);
231 			}
232 		}
233 		optlen = MAX(optlen, 1);	/* paranoia */
234 	}
235 
236 	DPFPRINTF("fingerprinted %s:%d  %d:%d:%d:%d:%llx (%d) "
237 	    "(TS=%s,M=%s%d,W=%s%d)\n",
238 	    srcname, ntohs(tcp->th_sport),
239 	    fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
240 	    fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
241 	    (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
242 	    (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
243 	    (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
244 	    fp.fp_mss,
245 	    (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
246 	    (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
247 	    fp.fp_wscale);
248 
249 	if ((fpresult = pf_osfp_find(&pf_osfp_list, &fp,
250 	    PF_OSFP_MAXTTL_OFFSET)))
251 		return (&fpresult->fp_oses);
252 	return (NULL);
253 }
254 
255 /* Match a fingerprint ID against a list of OSes */
256 int
257 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
258 {
259 	struct pf_osfp_entry *entry;
260 	int os_class, os_version, os_subtype;
261 	int en_class, en_version, en_subtype;
262 
263 	if (os == PF_OSFP_ANY)
264 		return (1);
265 	if (list == NULL) {
266 		DPFPRINTF("osfp no match against %x\n", os);
267 		return (os == PF_OSFP_UNKNOWN);
268 	}
269 	PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
270 	SLIST_FOREACH(entry, list, fp_entry) {
271 		PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
272 		if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
273 		    (os_version == PF_OSFP_ANY || en_version == os_version) &&
274 		    (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
275 			DPFPRINTF("osfp matched %s %s %s  %x==%x\n",
276 			    entry->fp_class_nm, entry->fp_version_nm,
277 			    entry->fp_subtype_nm, os, entry->fp_os);
278 			return (1);
279 		}
280 	}
281 	DPFPRINTF("fingerprint 0x%x didn't match\n", os);
282 	return (0);
283 }
284 
285 /* Initialize the OS fingerprint system */
286 void
287 pf_osfp_initialize(void)
288 {
289 	SLIST_INIT(&pf_osfp_list);
290 }
291 
292 /* Flush the fingerprint list */
293 void
294 pf_osfp_flush(void)
295 {
296 	struct pf_os_fingerprint *fp;
297 	struct pf_osfp_entry *entry;
298 
299 	while ((fp = SLIST_FIRST(&pf_osfp_list))) {
300 		SLIST_REMOVE_HEAD(&pf_osfp_list, fp_next);
301 		while ((entry = SLIST_FIRST(&fp->fp_oses))) {
302 			SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
303 			kfree(entry, M_PFOSFPENTRYPL);
304 		}
305 		kfree(fp, M_PFOSFPPL);
306 	}
307 }
308 
309 
310 /* Add a fingerprint */
311 int
312 pf_osfp_add(struct pf_osfp_ioctl *fpioc)
313 {
314 	struct pf_os_fingerprint *fp, fpadd;
315 	struct pf_osfp_entry *entry;
316 
317 	memset(&fpadd, 0, sizeof(fpadd));
318 	fpadd.fp_tcpopts = fpioc->fp_tcpopts;
319 	fpadd.fp_wsize = fpioc->fp_wsize;
320 	fpadd.fp_psize = fpioc->fp_psize;
321 	fpadd.fp_mss = fpioc->fp_mss;
322 	fpadd.fp_flags = fpioc->fp_flags;
323 	fpadd.fp_optcnt = fpioc->fp_optcnt;
324 	fpadd.fp_wscale = fpioc->fp_wscale;
325 	fpadd.fp_ttl = fpioc->fp_ttl;
326 
327 #if 0	/* XXX RYAN wants to fix logging */
328 	DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
329 	    "(TS=%s,M=%s%d,W=%s%d) %x\n",
330 	    fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
331 	    fpioc->fp_os.fp_subtype_nm,
332 	    (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
333 	    (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
334 	    (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
335 	    (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
336 	    fpadd.fp_wsize,
337 	    fpadd.fp_ttl,
338 	    (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
339 	    (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
340 	    (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
341 	    fpadd.fp_psize,
342 	    (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
343 	    (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
344 	    (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
345 	    (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
346 	    fpadd.fp_mss,
347 	    (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
348 	    (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
349 	    fpadd.fp_wscale,
350 	    fpioc->fp_os.fp_os);
351 #endif
352 
353 	if ((fp = pf_osfp_find_exact(&pf_osfp_list, &fpadd))) {
354 		 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
355 			if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
356 				return (EEXIST);
357 		}
358 		if ((entry = kmalloc(sizeof(struct pf_osfp_entry),
359 		    M_PFOSFPENTRYPL, M_WAITOK|M_NULLOK)) == NULL)
360 			return (ENOMEM);
361 	} else {
362 		if ((fp = kmalloc(sizeof(struct pf_os_fingerprint),
363 		    M_PFOSFPPL, M_WAITOK|M_NULLOK)) == NULL)
364 			return (ENOMEM);
365 		memset(fp, 0, sizeof(*fp));
366 		fp->fp_tcpopts = fpioc->fp_tcpopts;
367 		fp->fp_wsize = fpioc->fp_wsize;
368 		fp->fp_psize = fpioc->fp_psize;
369 		fp->fp_mss = fpioc->fp_mss;
370 		fp->fp_flags = fpioc->fp_flags;
371 		fp->fp_optcnt = fpioc->fp_optcnt;
372 		fp->fp_wscale = fpioc->fp_wscale;
373 		fp->fp_ttl = fpioc->fp_ttl;
374 		SLIST_INIT(&fp->fp_oses);
375 		if ((entry = kmalloc(sizeof(struct pf_osfp_entry),
376 		    M_PFOSFPENTRYPL, M_WAITOK|M_NULLOK)) == NULL) {
377 			kfree(fp, M_PFOSFPPL);
378 			return (ENOMEM);
379 		}
380 		pf_osfp_insert(&pf_osfp_list, fp);
381 	}
382 	memcpy(entry, &fpioc->fp_os, sizeof(*entry));
383 
384 	/* Make sure the strings are NUL terminated */
385 	entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
386 	entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
387 	entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
388 
389 	SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
390 
391 #ifdef PFDEBUG
392 	if ((fp = pf_osfp_validate()))
393 		kprintf("Invalid fingerprint list\n");
394 #endif /* PFDEBUG */
395 	return (0);
396 }
397 
398 
399 /* Find a fingerprint in the list */
400 struct pf_os_fingerprint *
401 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
402     u_int8_t ttldiff)
403 {
404 	struct pf_os_fingerprint *f;
405 
406 #define MATCH_INT(_MOD, _DC, _field)					\
407 	if ((f->fp_flags & _DC) == 0) {					\
408 		if ((f->fp_flags & _MOD) == 0) {			\
409 			if (f->_field != find->_field)			\
410 				continue;				\
411 		} else {						\
412 			if (f->_field == 0 || find->_field % f->_field)	\
413 				continue;				\
414 		}							\
415 	}
416 
417 	SLIST_FOREACH(f, list, fp_next) {
418 		if (f->fp_tcpopts != find->fp_tcpopts ||
419 		    f->fp_optcnt != find->fp_optcnt ||
420 		    f->fp_ttl < find->fp_ttl ||
421 		    f->fp_ttl - find->fp_ttl > ttldiff ||
422 		    (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
423 		    (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
424 			continue;
425 
426 		MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
427 		MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
428 		MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
429 		if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
430 			if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
431 				if (find->fp_mss == 0)
432 					continue;
433 
434 /* Some "smart" NAT devices and DSL routers will tweak the MSS size and
435  * will set it to whatever is suitable for the link type.
436  */
437 #define SMART_MSS	1460
438 				if ((find->fp_wsize % find->fp_mss ||
439 				    find->fp_wsize / find->fp_mss !=
440 				    f->fp_wsize) &&
441 				    (find->fp_wsize % SMART_MSS ||
442 				    find->fp_wsize / SMART_MSS !=
443 				    f->fp_wsize))
444 					continue;
445 			} else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
446 				if (find->fp_mss == 0)
447 					continue;
448 
449 #define MTUOFF	(sizeof(struct ip) + sizeof(struct tcphdr))
450 #define SMART_MTU	(SMART_MSS + MTUOFF)
451 				if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
452 				    find->fp_wsize / (find->fp_mss + MTUOFF) !=
453 				    f->fp_wsize) &&
454 				    (find->fp_wsize % SMART_MTU ||
455 				    find->fp_wsize / SMART_MTU !=
456 				    f->fp_wsize))
457 					continue;
458 			} else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
459 				if (f->fp_wsize == 0 || find->fp_wsize %
460 				    f->fp_wsize)
461 					continue;
462 			} else {
463 				if (f->fp_wsize != find->fp_wsize)
464 					continue;
465 			}
466 		}
467 		return (f);
468 	}
469 
470 	return (NULL);
471 }
472 
473 /* Find an exact fingerprint in the list */
474 struct pf_os_fingerprint *
475 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
476 {
477 	struct pf_os_fingerprint *f;
478 
479 	SLIST_FOREACH(f, list, fp_next) {
480 		if (f->fp_tcpopts == find->fp_tcpopts &&
481 		    f->fp_wsize == find->fp_wsize &&
482 		    f->fp_psize == find->fp_psize &&
483 		    f->fp_mss == find->fp_mss &&
484 		    f->fp_flags == find->fp_flags &&
485 		    f->fp_optcnt == find->fp_optcnt &&
486 		    f->fp_wscale == find->fp_wscale &&
487 		    f->fp_ttl == find->fp_ttl)
488 			return (f);
489 	}
490 
491 	return (NULL);
492 }
493 
494 /* Insert a fingerprint into the list */
495 void
496 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
497 {
498 	struct pf_os_fingerprint *f, *prev = NULL;
499 
500 	/* XXX need to go semi tree based.  can key on tcp options */
501 
502 	SLIST_FOREACH(f, list, fp_next)
503 		prev = f;
504 	if (prev)
505 		SLIST_INSERT_AFTER(prev, ins, fp_next);
506 	else
507 		SLIST_INSERT_HEAD(list, ins, fp_next);
508 }
509 
510 /* Fill a fingerprint by its number (from an ioctl) */
511 int
512 pf_osfp_get(struct pf_osfp_ioctl *fpioc)
513 {
514 	struct pf_os_fingerprint *fp;
515 	struct pf_osfp_entry *entry;
516 	int num = fpioc->fp_getnum;
517 	int i = 0;
518 
519 
520 	memset(fpioc, 0, sizeof(*fpioc));
521 	SLIST_FOREACH(fp, &pf_osfp_list, fp_next) {
522 		SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
523 			if (i++ == num) {
524 				fpioc->fp_mss = fp->fp_mss;
525 				fpioc->fp_wsize = fp->fp_wsize;
526 				fpioc->fp_flags = fp->fp_flags;
527 				fpioc->fp_psize = fp->fp_psize;
528 				fpioc->fp_ttl = fp->fp_ttl;
529 				fpioc->fp_wscale = fp->fp_wscale;
530 				fpioc->fp_getnum = num;
531 				memcpy(&fpioc->fp_os, entry,
532 				    sizeof(fpioc->fp_os));
533 				return (0);
534 			}
535 		}
536 	}
537 
538 	return (EBUSY);
539 }
540 
541 
542 /* Validate that each signature is reachable */
543 struct pf_os_fingerprint *
544 pf_osfp_validate(void)
545 {
546 	struct pf_os_fingerprint *f, *f2, find;
547 
548 	SLIST_FOREACH(f, &pf_osfp_list, fp_next) {
549 		memcpy(&find, f, sizeof(find));
550 
551 		/* We do a few MSS/th_win percolations to make things unique */
552 		if (find.fp_mss == 0)
553 			find.fp_mss = 128;
554 		if (f->fp_flags & PF_OSFP_WSIZE_MSS)
555 			find.fp_wsize *= find.fp_mss;
556 		else if (f->fp_flags & PF_OSFP_WSIZE_MTU)
557 			find.fp_wsize *= (find.fp_mss + 40);
558 		else if (f->fp_flags & PF_OSFP_WSIZE_MOD)
559 			find.fp_wsize *= 2;
560 		if (f != (f2 = pf_osfp_find(&pf_osfp_list, &find, 0))) {
561 			if (f2)
562 				kprintf("Found \"%s %s %s\" instead of "
563 				    "\"%s %s %s\"\n",
564 				    SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
565 				    SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
566 				    SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
567 				    SLIST_FIRST(&f->fp_oses)->fp_class_nm,
568 				    SLIST_FIRST(&f->fp_oses)->fp_version_nm,
569 				    SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
570 			else
571 				kprintf("Couldn't find \"%s %s %s\"\n",
572 				    SLIST_FIRST(&f->fp_oses)->fp_class_nm,
573 				    SLIST_FIRST(&f->fp_oses)->fp_version_nm,
574 				    SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
575 			return (f);
576 		}
577 	}
578 	return (NULL);
579 }
580