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#ifdef __FreeBSD__
21#include <sys/cdefs.h>
22__FBSDID("$FreeBSD$");
23#endif
24
25#include <sys/param.h>
26#include <sys/socket.h>
27#ifdef _KERNEL
28#include <sys/systm.h>
29#ifndef __FreeBSD__
30#include <sys/pool.h>
31#endif
32#endif /* _KERNEL */
33#include <sys/mbuf.h>
34
35#include <netinet/in.h>
36#include <netinet/in_systm.h>
37#include <netinet/ip.h>
38#include <netinet/tcp.h>
39
40#include <net/if.h>
41#include <net/pfvar.h>
42
43#include <netinet/ip6.h>
44#ifdef _KERNEL
45#include <netinet6/in6_var.h>
46#endif
47
48
49#ifdef _KERNEL
50#ifdef __FreeBSD__
51#define	DPFPRINTF(format, x...)		\
52	if (V_pf_status.debug >= PF_DEBUG_NOISY)	\
53		printf(format , ##x)
54#else
55#define	DPFPRINTF(format, x...)		\
56	if (pf_status.debug >= PF_DEBUG_NOISY)	\
57		printf(format , ##x)
58#endif
59#ifdef __FreeBSD__
60typedef uma_zone_t pool_t;
61#else
62typedef struct pool pool_t;
63#endif
64
65#else
66/* Userland equivalents so we can lend code to tcpdump et al. */
67
68#include <arpa/inet.h>
69#include <errno.h>
70#include <stdio.h>
71#include <stdlib.h>
72#include <string.h>
73#include <netdb.h>
74#define	pool_t			int
75#define	pool_get(pool, flags)	malloc(*(pool))
76#define	pool_put(pool, item)	free(item)
77#define	pool_init(pool, size, a, ao, f, m, p)	(*(pool)) = (size)
78
79#ifdef __FreeBSD__
80#define	NTOHS(x) (x) = ntohs((u_int16_t)(x))
81#endif
82
83#ifdef PFDEBUG
84#include <sys/stdarg.h>
85#define	DPFPRINTF(format, x...)	fprintf(stderr, format , ##x)
86#else
87#define	DPFPRINTF(format, x...)	((void)0)
88#endif /* PFDEBUG */
89#endif /* _KERNEL */
90
91
92#ifdef __FreeBSD__
93SLIST_HEAD(pf_osfp_list, pf_os_fingerprint);
94VNET_DEFINE(struct pf_osfp_list,	pf_osfp_list);
95#define	V_pf_osfp_list			VNET(pf_osfp_list)
96VNET_DEFINE(pool_t,			pf_osfp_entry_pl);
97#define	pf_osfp_entry_pl		VNET(pf_osfp_entry_pl)
98VNET_DEFINE(pool_t,			pf_osfp_pl);
99#define	pf_osfp_pl			VNET(pf_osfp_pl)
100#else
101SLIST_HEAD(pf_osfp_list, pf_os_fingerprint) pf_osfp_list;
102pool_t pf_osfp_entry_pl;
103pool_t pf_osfp_pl;
104#endif
105
106struct pf_os_fingerprint	*pf_osfp_find(struct pf_osfp_list *,
107				    struct pf_os_fingerprint *, u_int8_t);
108struct pf_os_fingerprint	*pf_osfp_find_exact(struct pf_osfp_list *,
109				    struct pf_os_fingerprint *);
110void				 pf_osfp_insert(struct pf_osfp_list *,
111				    struct pf_os_fingerprint *);
112
113
114#ifdef _KERNEL
115/*
116 * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
117 * Returns the list of possible OSes.
118 */
119struct pf_osfp_enlist *
120pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
121    const struct tcphdr *tcp)
122{
123	struct ip *ip;
124	struct ip6_hdr *ip6;
125	char hdr[60];
126
127	if ((pd->af != PF_INET && pd->af != PF_INET6) ||
128	    pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
129		return (NULL);
130
131	if (pd->af == PF_INET) {
132		ip = mtod(m, struct ip *);
133		ip6 = (struct ip6_hdr *)NULL;
134	} else {
135		ip = (struct ip *)NULL;
136		ip6 = mtod(m, struct ip6_hdr *);
137	}
138	if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
139	    pd->af)) return (NULL);
140
141	return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
142}
143#endif /* _KERNEL */
144
145struct pf_osfp_enlist *
146pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
147{
148	struct pf_os_fingerprint fp, *fpresult;
149	int cnt, optlen = 0;
150	const u_int8_t *optp;
151#ifdef _KERNEL
152	char srcname[128];
153#else
154	char srcname[NI_MAXHOST];
155#endif
156
157	if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
158		return (NULL);
159	if (ip) {
160		if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
161			return (NULL);
162	}
163
164	memset(&fp, 0, sizeof(fp));
165
166	if (ip) {
167#ifndef _KERNEL
168		struct sockaddr_in sin;
169#endif
170
171		fp.fp_psize = ntohs(ip->ip_len);
172		fp.fp_ttl = ip->ip_ttl;
173		if (ip->ip_off & htons(IP_DF))
174			fp.fp_flags |= PF_OSFP_DF;
175#ifdef _KERNEL
176		strlcpy(srcname, inet_ntoa(ip->ip_src), sizeof(srcname));
177#else
178		memset(&sin, 0, sizeof(sin));
179		sin.sin_family = AF_INET;
180		sin.sin_len = sizeof(struct sockaddr_in);
181		sin.sin_addr = ip->ip_src;
182		(void)getnameinfo((struct sockaddr *)&sin,
183		    sizeof(struct sockaddr_in), srcname, sizeof(srcname),
184		    NULL, 0, NI_NUMERICHOST);
185#endif
186	}
187#ifdef INET6
188	else if (ip6) {
189#ifndef _KERNEL
190		struct sockaddr_in6 sin6;
191#endif
192
193		/* jumbo payload? */
194		fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
195		fp.fp_ttl = ip6->ip6_hlim;
196		fp.fp_flags |= PF_OSFP_DF;
197		fp.fp_flags |= PF_OSFP_INET6;
198#ifdef _KERNEL
199		strlcpy(srcname, ip6_sprintf((struct in6_addr *)&ip6->ip6_src),
200		    sizeof(srcname));
201#else
202		memset(&sin6, 0, sizeof(sin6));
203		sin6.sin6_family = AF_INET6;
204		sin6.sin6_len = sizeof(struct sockaddr_in6);
205		sin6.sin6_addr = ip6->ip6_src;
206		(void)getnameinfo((struct sockaddr *)&sin6,
207		    sizeof(struct sockaddr_in6), srcname, sizeof(srcname),
208		    NULL, 0, NI_NUMERICHOST);
209#endif
210	}
211#endif
212	else
213		return (NULL);
214	fp.fp_wsize = ntohs(tcp->th_win);
215
216
217	cnt = (tcp->th_off << 2) - sizeof(*tcp);
218	optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
219	for (; cnt > 0; cnt -= optlen, optp += optlen) {
220		if (*optp == TCPOPT_EOL)
221			break;
222
223		fp.fp_optcnt++;
224		if (*optp == TCPOPT_NOP) {
225			fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
226			    PF_OSFP_TCPOPT_NOP;
227			optlen = 1;
228		} else {
229			if (cnt < 2)
230				return (NULL);
231			optlen = optp[1];
232			if (optlen > cnt || optlen < 2)
233				return (NULL);
234			switch (*optp) {
235			case TCPOPT_MAXSEG:
236				if (optlen >= TCPOLEN_MAXSEG)
237					memcpy(&fp.fp_mss, &optp[2],
238					    sizeof(fp.fp_mss));
239				fp.fp_tcpopts = (fp.fp_tcpopts <<
240				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
241				NTOHS(fp.fp_mss);
242				break;
243			case TCPOPT_WINDOW:
244				if (optlen >= TCPOLEN_WINDOW)
245					memcpy(&fp.fp_wscale, &optp[2],
246					    sizeof(fp.fp_wscale));
247				NTOHS(fp.fp_wscale);
248				fp.fp_tcpopts = (fp.fp_tcpopts <<
249				    PF_OSFP_TCPOPT_BITS) |
250				    PF_OSFP_TCPOPT_WSCALE;
251				break;
252			case TCPOPT_SACK_PERMITTED:
253				fp.fp_tcpopts = (fp.fp_tcpopts <<
254				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
255				break;
256			case TCPOPT_TIMESTAMP:
257				if (optlen >= TCPOLEN_TIMESTAMP) {
258					u_int32_t ts;
259					memcpy(&ts, &optp[2], sizeof(ts));
260					if (ts == 0)
261						fp.fp_flags |= PF_OSFP_TS0;
262
263				}
264				fp.fp_tcpopts = (fp.fp_tcpopts <<
265				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
266				break;
267			default:
268				return (NULL);
269			}
270		}
271		optlen = MAX(optlen, 1);	/* paranoia */
272	}
273
274	DPFPRINTF("fingerprinted %s:%d  %d:%d:%d:%d:%llx (%d) "
275	    "(TS=%s,M=%s%d,W=%s%d)\n",
276	    srcname, ntohs(tcp->th_sport),
277	    fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
278	    fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
279	    (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
280	    (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
281	    (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
282	    fp.fp_mss,
283	    (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
284	    (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
285	    fp.fp_wscale);
286
287#ifdef __FreeBSD__
288	if ((fpresult = pf_osfp_find(&V_pf_osfp_list, &fp,
289#else
290	if ((fpresult = pf_osfp_find(&pf_osfp_list, &fp,
291#endif
292	    PF_OSFP_MAXTTL_OFFSET)))
293		return (&fpresult->fp_oses);
294	return (NULL);
295}
296
297/* Match a fingerprint ID against a list of OSes */
298int
299pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
300{
301	struct pf_osfp_entry *entry;
302	int os_class, os_version, os_subtype;
303	int en_class, en_version, en_subtype;
304
305	if (os == PF_OSFP_ANY)
306		return (1);
307	if (list == NULL) {
308		DPFPRINTF("osfp no match against %x\n", os);
309		return (os == PF_OSFP_UNKNOWN);
310	}
311	PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
312	SLIST_FOREACH(entry, list, fp_entry) {
313		PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
314		if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
315		    (os_version == PF_OSFP_ANY || en_version == os_version) &&
316		    (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
317			DPFPRINTF("osfp matched %s %s %s  %x==%x\n",
318			    entry->fp_class_nm, entry->fp_version_nm,
319			    entry->fp_subtype_nm, os, entry->fp_os);
320			return (1);
321		}
322	}
323	DPFPRINTF("fingerprint 0x%x didn't match\n", os);
324	return (0);
325}
326
327/* Initialize the OS fingerprint system */
328#ifdef __FreeBSD__
329int
330#else
331void
332#endif
333pf_osfp_initialize(void)
334{
335#if defined(__FreeBSD__) && defined(_KERNEL)
336	int error = ENOMEM;
337
338	do {
339		pf_osfp_entry_pl = pf_osfp_pl = NULL;
340		UMA_CREATE(pf_osfp_entry_pl, struct pf_osfp_entry, "pfospfen");
341		UMA_CREATE(pf_osfp_pl, struct pf_os_fingerprint, "pfosfp");
342		error = 0;
343	} while(0);
344
345	SLIST_INIT(&V_pf_osfp_list);
346#else
347	pool_init(&pf_osfp_entry_pl, sizeof(struct pf_osfp_entry), 0, 0, 0,
348	    "pfosfpen", &pool_allocator_nointr);
349	pool_init(&pf_osfp_pl, sizeof(struct pf_os_fingerprint), 0, 0, 0,
350	    "pfosfp", &pool_allocator_nointr);
351	SLIST_INIT(&pf_osfp_list);
352#endif
353
354#ifdef __FreeBSD__
355#ifdef _KERNEL
356	return (error);
357#else
358	return (0);
359#endif
360#endif
361}
362
363#if defined(__FreeBSD__) && (_KERNEL)
364void
365pf_osfp_cleanup(void)
366{
367
368	UMA_DESTROY(pf_osfp_entry_pl);
369	UMA_DESTROY(pf_osfp_pl);
370}
371#endif
372
373/* Flush the fingerprint list */
374void
375pf_osfp_flush(void)
376{
377	struct pf_os_fingerprint *fp;
378	struct pf_osfp_entry *entry;
379
380#ifdef __FreeBSD__
381	while ((fp = SLIST_FIRST(&V_pf_osfp_list))) {
382		SLIST_REMOVE_HEAD(&V_pf_osfp_list, fp_next);
383#else
384	while ((fp = SLIST_FIRST(&pf_osfp_list))) {
385		SLIST_REMOVE_HEAD(&pf_osfp_list, fp_next);
386#endif
387		while ((entry = SLIST_FIRST(&fp->fp_oses))) {
388			SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
389			pool_put(&pf_osfp_entry_pl, entry);
390		}
391		pool_put(&pf_osfp_pl, fp);
392	}
393}
394
395
396/* Add a fingerprint */
397int
398pf_osfp_add(struct pf_osfp_ioctl *fpioc)
399{
400	struct pf_os_fingerprint *fp, fpadd;
401	struct pf_osfp_entry *entry;
402
403	memset(&fpadd, 0, sizeof(fpadd));
404	fpadd.fp_tcpopts = fpioc->fp_tcpopts;
405	fpadd.fp_wsize = fpioc->fp_wsize;
406	fpadd.fp_psize = fpioc->fp_psize;
407	fpadd.fp_mss = fpioc->fp_mss;
408	fpadd.fp_flags = fpioc->fp_flags;
409	fpadd.fp_optcnt = fpioc->fp_optcnt;
410	fpadd.fp_wscale = fpioc->fp_wscale;
411	fpadd.fp_ttl = fpioc->fp_ttl;
412
413#if 0	/* XXX RYAN wants to fix logging */
414	DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
415	    "(TS=%s,M=%s%d,W=%s%d) %x\n",
416	    fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
417	    fpioc->fp_os.fp_subtype_nm,
418	    (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
419	    (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
420	    (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
421	    (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
422	    fpadd.fp_wsize,
423	    fpadd.fp_ttl,
424	    (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
425	    (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
426	    (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
427	    fpadd.fp_psize,
428	    (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
429	    (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
430	    (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
431	    (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
432	    fpadd.fp_mss,
433	    (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
434	    (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
435	    fpadd.fp_wscale,
436	    fpioc->fp_os.fp_os);
437#endif
438
439#ifdef __FreeBSD__
440	if ((fp = pf_osfp_find_exact(&V_pf_osfp_list, &fpadd))) {
441#else
442	if ((fp = pf_osfp_find_exact(&pf_osfp_list, &fpadd))) {
443#endif
444		 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
445			if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
446				return (EEXIST);
447		}
448		if ((entry = pool_get(&pf_osfp_entry_pl,
449#ifdef __FreeBSD__
450		    PR_NOWAIT)) == NULL)
451#else
452		    PR_WAITOK|PR_LIMITFAIL)) == NULL)
453#endif
454			return (ENOMEM);
455	} else {
456		if ((fp = pool_get(&pf_osfp_pl,
457#ifdef __FreeBSD__
458		    PR_NOWAIT)) == NULL)
459#else
460		    PR_WAITOK|PR_LIMITFAIL)) == NULL)
461#endif
462			return (ENOMEM);
463		memset(fp, 0, sizeof(*fp));
464		fp->fp_tcpopts = fpioc->fp_tcpopts;
465		fp->fp_wsize = fpioc->fp_wsize;
466		fp->fp_psize = fpioc->fp_psize;
467		fp->fp_mss = fpioc->fp_mss;
468		fp->fp_flags = fpioc->fp_flags;
469		fp->fp_optcnt = fpioc->fp_optcnt;
470		fp->fp_wscale = fpioc->fp_wscale;
471		fp->fp_ttl = fpioc->fp_ttl;
472		SLIST_INIT(&fp->fp_oses);
473		if ((entry = pool_get(&pf_osfp_entry_pl,
474#ifdef __FreeBSD__
475		    PR_NOWAIT)) == NULL) {
476#else
477		    PR_WAITOK|PR_LIMITFAIL)) == NULL) {
478#endif
479			pool_put(&pf_osfp_pl, fp);
480			return (ENOMEM);
481		}
482#ifdef __FreeBSD__
483		pf_osfp_insert(&V_pf_osfp_list, fp);
484#else
485		pf_osfp_insert(&pf_osfp_list, fp);
486#endif
487	}
488	memcpy(entry, &fpioc->fp_os, sizeof(*entry));
489
490	/* Make sure the strings are NUL terminated */
491	entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
492	entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
493	entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
494
495	SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
496
497#ifdef PFDEBUG
498	if ((fp = pf_osfp_validate()))
499		printf("Invalid fingerprint list\n");
500#endif /* PFDEBUG */
501	return (0);
502}
503
504
505/* Find a fingerprint in the list */
506struct pf_os_fingerprint *
507pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
508    u_int8_t ttldiff)
509{
510	struct pf_os_fingerprint *f;
511
512#define	MATCH_INT(_MOD, _DC, _field)					\
513	if ((f->fp_flags & _DC) == 0) {					\
514		if ((f->fp_flags & _MOD) == 0) {			\
515			if (f->_field != find->_field)			\
516				continue;				\
517		} else {						\
518			if (f->_field == 0 || find->_field % f->_field)	\
519				continue;				\
520		}							\
521	}
522
523	SLIST_FOREACH(f, list, fp_next) {
524		if (f->fp_tcpopts != find->fp_tcpopts ||
525		    f->fp_optcnt != find->fp_optcnt ||
526		    f->fp_ttl < find->fp_ttl ||
527		    f->fp_ttl - find->fp_ttl > ttldiff ||
528		    (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
529		    (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
530			continue;
531
532		MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
533		MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
534		MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
535		if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
536			if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
537				if (find->fp_mss == 0)
538					continue;
539
540/*
541 * Some "smart" NAT devices and DSL routers will tweak the MSS size and
542 * will set it to whatever is suitable for the link type.
543 */
544#define	SMART_MSS	1460
545				if ((find->fp_wsize % find->fp_mss ||
546				    find->fp_wsize / find->fp_mss !=
547				    f->fp_wsize) &&
548				    (find->fp_wsize % SMART_MSS ||
549				    find->fp_wsize / SMART_MSS !=
550				    f->fp_wsize))
551					continue;
552			} else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
553				if (find->fp_mss == 0)
554					continue;
555
556#define	MTUOFF		(sizeof(struct ip) + sizeof(struct tcphdr))
557#define	SMART_MTU	(SMART_MSS + MTUOFF)
558				if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
559				    find->fp_wsize / (find->fp_mss + MTUOFF) !=
560				    f->fp_wsize) &&
561				    (find->fp_wsize % SMART_MTU ||
562				    find->fp_wsize / SMART_MTU !=
563				    f->fp_wsize))
564					continue;
565			} else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
566				if (f->fp_wsize == 0 || find->fp_wsize %
567				    f->fp_wsize)
568					continue;
569			} else {
570				if (f->fp_wsize != find->fp_wsize)
571					continue;
572			}
573		}
574		return (f);
575	}
576
577	return (NULL);
578}
579
580/* Find an exact fingerprint in the list */
581struct pf_os_fingerprint *
582pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
583{
584	struct pf_os_fingerprint *f;
585
586	SLIST_FOREACH(f, list, fp_next) {
587		if (f->fp_tcpopts == find->fp_tcpopts &&
588		    f->fp_wsize == find->fp_wsize &&
589		    f->fp_psize == find->fp_psize &&
590		    f->fp_mss == find->fp_mss &&
591		    f->fp_flags == find->fp_flags &&
592		    f->fp_optcnt == find->fp_optcnt &&
593		    f->fp_wscale == find->fp_wscale &&
594		    f->fp_ttl == find->fp_ttl)
595			return (f);
596	}
597
598	return (NULL);
599}
600
601/* Insert a fingerprint into the list */
602void
603pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
604{
605	struct pf_os_fingerprint *f, *prev = NULL;
606
607	/* XXX need to go semi tree based.  can key on tcp options */
608
609	SLIST_FOREACH(f, list, fp_next)
610		prev = f;
611	if (prev)
612		SLIST_INSERT_AFTER(prev, ins, fp_next);
613	else
614		SLIST_INSERT_HEAD(list, ins, fp_next);
615}
616
617/* Fill a fingerprint by its number (from an ioctl) */
618int
619pf_osfp_get(struct pf_osfp_ioctl *fpioc)
620{
621	struct pf_os_fingerprint *fp;
622	struct pf_osfp_entry *entry;
623	int num = fpioc->fp_getnum;
624	int i = 0;
625
626
627	memset(fpioc, 0, sizeof(*fpioc));
628#ifdef __FreeBSD__
629	SLIST_FOREACH(fp, &V_pf_osfp_list, fp_next) {
630#else
631	SLIST_FOREACH(fp, &pf_osfp_list, fp_next) {
632#endif
633		SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
634			if (i++ == num) {
635				fpioc->fp_mss = fp->fp_mss;
636				fpioc->fp_wsize = fp->fp_wsize;
637				fpioc->fp_flags = fp->fp_flags;
638				fpioc->fp_psize = fp->fp_psize;
639				fpioc->fp_ttl = fp->fp_ttl;
640				fpioc->fp_wscale = fp->fp_wscale;
641				fpioc->fp_getnum = num;
642				memcpy(&fpioc->fp_os, entry,
643				    sizeof(fpioc->fp_os));
644				return (0);
645			}
646		}
647	}
648
649	return (EBUSY);
650}
651
652
653/* Validate that each signature is reachable */
654struct pf_os_fingerprint *
655pf_osfp_validate(void)
656{
657	struct pf_os_fingerprint *f, *f2, find;
658
659#ifdef __FreeBSD__
660	SLIST_FOREACH(f, &V_pf_osfp_list, fp_next) {
661#else
662	SLIST_FOREACH(f, &pf_osfp_list, fp_next) {
663#endif
664		memcpy(&find, f, sizeof(find));
665
666		/* We do a few MSS/th_win percolations to make things unique */
667		if (find.fp_mss == 0)
668			find.fp_mss = 128;
669		if (f->fp_flags & PF_OSFP_WSIZE_MSS)
670			find.fp_wsize *= find.fp_mss;
671		else if (f->fp_flags & PF_OSFP_WSIZE_MTU)
672			find.fp_wsize *= (find.fp_mss + 40);
673		else if (f->fp_flags & PF_OSFP_WSIZE_MOD)
674			find.fp_wsize *= 2;
675#ifdef __FreeBSD__
676		if (f != (f2 = pf_osfp_find(&V_pf_osfp_list, &find, 0))) {
677#else
678		if (f != (f2 = pf_osfp_find(&pf_osfp_list, &find, 0))) {
679#endif
680			if (f2)
681				printf("Found \"%s %s %s\" instead of "
682				    "\"%s %s %s\"\n",
683				    SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
684				    SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
685				    SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
686				    SLIST_FIRST(&f->fp_oses)->fp_class_nm,
687				    SLIST_FIRST(&f->fp_oses)->fp_version_nm,
688				    SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
689			else
690				printf("Couldn't find \"%s %s %s\"\n",
691				    SLIST_FIRST(&f->fp_oses)->fp_class_nm,
692				    SLIST_FIRST(&f->fp_oses)->fp_version_nm,
693				    SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
694			return (f);
695		}
696	}
697	return (NULL);
698}
699