xref: /freebsd/sys/netpfil/pf/pf_osfp.c (revision 488ab515d6cc02f6f743f0badfc8e94eb553cd30) 
1 /*-
2  * SPDX-License-Identifier: ISC
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  *	$OpenBSD: pf_osfp.c,v 1.14 2008/06/12 18:17:01 henning Exp $
19  */
20 
21 #include <sys/cdefs.h>
22 __FBSDID("$FreeBSD$");
23 
24 #include "opt_inet6.h"
25 
26 #include <sys/param.h>
27 #include <sys/kernel.h>
28 #include <sys/lock.h>
29 #include <sys/mbuf.h>
30 #include <sys/rwlock.h>
31 #include <sys/socket.h>
32 
33 #include <netinet/in.h>
34 #include <netinet/ip.h>
35 #include <netinet/tcp.h>
36 
37 #include <net/if.h>
38 #include <net/vnet.h>
39 #include <net/pfvar.h>
40 
41 #ifdef INET6
42 #include <netinet/ip6.h>
43 #endif
44 
45 static MALLOC_DEFINE(M_PFOSFP, "pf_osfp", "pf(4) operating system fingerprints");
46 #define	DPFPRINTF(format, x...)		\
47 	if (V_pf_status.debug >= PF_DEBUG_NOISY)	\
48 		printf(format , ##x)
49 
50 SLIST_HEAD(pf_osfp_list, pf_os_fingerprint);
51 static VNET_DEFINE(struct pf_osfp_list,	pf_osfp_list) =
52 	SLIST_HEAD_INITIALIZER();
53 #define	V_pf_osfp_list			VNET(pf_osfp_list)
54 
55 static struct pf_osfp_enlist	*pf_osfp_fingerprint_hdr(const struct ip *,
56 				    const struct ip6_hdr *,
57 				    const struct tcphdr *);
58 static struct pf_os_fingerprint	*pf_osfp_find(struct pf_osfp_list *,
59 				    struct pf_os_fingerprint *, u_int8_t);
60 static struct pf_os_fingerprint	*pf_osfp_find_exact(struct pf_osfp_list *,
61 				    struct pf_os_fingerprint *);
62 static void			 pf_osfp_insert(struct pf_osfp_list *,
63 				    struct pf_os_fingerprint *);
64 #ifdef PFDEBUG
65 static struct pf_os_fingerprint	*pf_osfp_validate(void);
66 #endif
67 
68 /*
69  * Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
70  * Returns the list of possible OSes.
71  */
72 struct pf_osfp_enlist *
73 pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
74     const struct tcphdr *tcp)
75 {
76 	struct ip *ip;
77 	struct ip6_hdr *ip6;
78 	char hdr[60];
79 
80 	if ((pd->af != PF_INET && pd->af != PF_INET6) ||
81 	    pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
82 		return (NULL);
83 
84 	if (pd->af == PF_INET) {
85 		ip = mtod(m, struct ip *);
86 		ip6 = (struct ip6_hdr *)NULL;
87 	} else {
88 		ip = (struct ip *)NULL;
89 		ip6 = mtod(m, struct ip6_hdr *);
90 	}
91 	if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
92 	    pd->af)) return (NULL);
93 
94 	return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
95 }
96 
97 static struct pf_osfp_enlist *
98 pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
99 {
100 	struct pf_os_fingerprint fp, *fpresult;
101 	int cnt, optlen = 0;
102 	const u_int8_t *optp;
103 #ifdef INET6
104 	char srcname[INET6_ADDRSTRLEN];
105 #else
106 	char srcname[INET_ADDRSTRLEN];
107 #endif
108 
109 	if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
110 		return (NULL);
111 	if (ip) {
112 		if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
113 			return (NULL);
114 	}
115 
116 	memset(&fp, 0, sizeof(fp));
117 
118 	if (ip) {
119 		fp.fp_psize = ntohs(ip->ip_len);
120 		fp.fp_ttl = ip->ip_ttl;
121 		if (ip->ip_off & htons(IP_DF))
122 			fp.fp_flags |= PF_OSFP_DF;
123 		inet_ntoa_r(ip->ip_src, srcname);
124 	}
125 #ifdef INET6
126 	else if (ip6) {
127 		/* jumbo payload? */
128 		fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
129 		fp.fp_ttl = ip6->ip6_hlim;
130 		fp.fp_flags |= PF_OSFP_DF;
131 		fp.fp_flags |= PF_OSFP_INET6;
132 		ip6_sprintf(srcname, (const struct in6_addr *)&ip6->ip6_src);
133 	}
134 #endif
135 	else
136 		return (NULL);
137 	fp.fp_wsize = ntohs(tcp->th_win);
138 
139 
140 	cnt = (tcp->th_off << 2) - sizeof(*tcp);
141 	optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
142 	for (; cnt > 0; cnt -= optlen, optp += optlen) {
143 		if (*optp == TCPOPT_EOL)
144 			break;
145 
146 		fp.fp_optcnt++;
147 		if (*optp == TCPOPT_NOP) {
148 			fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
149 			    PF_OSFP_TCPOPT_NOP;
150 			optlen = 1;
151 		} else {
152 			if (cnt < 2)
153 				return (NULL);
154 			optlen = optp[1];
155 			if (optlen > cnt || optlen < 2)
156 				return (NULL);
157 			switch (*optp) {
158 			case TCPOPT_MAXSEG:
159 				if (optlen >= TCPOLEN_MAXSEG)
160 					memcpy(&fp.fp_mss, &optp[2],
161 					    sizeof(fp.fp_mss));
162 				fp.fp_tcpopts = (fp.fp_tcpopts <<
163 				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
164 				NTOHS(fp.fp_mss);
165 				break;
166 			case TCPOPT_WINDOW:
167 				if (optlen >= TCPOLEN_WINDOW)
168 					memcpy(&fp.fp_wscale, &optp[2],
169 					    sizeof(fp.fp_wscale));
170 				NTOHS(fp.fp_wscale);
171 				fp.fp_tcpopts = (fp.fp_tcpopts <<
172 				    PF_OSFP_TCPOPT_BITS) |
173 				    PF_OSFP_TCPOPT_WSCALE;
174 				break;
175 			case TCPOPT_SACK_PERMITTED:
176 				fp.fp_tcpopts = (fp.fp_tcpopts <<
177 				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
178 				break;
179 			case TCPOPT_TIMESTAMP:
180 				if (optlen >= TCPOLEN_TIMESTAMP) {
181 					u_int32_t ts;
182 					memcpy(&ts, &optp[2], sizeof(ts));
183 					if (ts == 0)
184 						fp.fp_flags |= PF_OSFP_TS0;
185 
186 				}
187 				fp.fp_tcpopts = (fp.fp_tcpopts <<
188 				    PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
189 				break;
190 			default:
191 				return (NULL);
192 			}
193 		}
194 		optlen = MAX(optlen, 1);	/* paranoia */
195 	}
196 
197 	DPFPRINTF("fingerprinted %s:%d  %d:%d:%d:%d:%llx (%d) "
198 	    "(TS=%s,M=%s%d,W=%s%d)\n",
199 	    srcname, ntohs(tcp->th_sport),
200 	    fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
201 	    fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
202 	    (fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
203 	    (fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
204 	    (fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
205 	    fp.fp_mss,
206 	    (fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
207 	    (fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
208 	    fp.fp_wscale);
209 
210 	if ((fpresult = pf_osfp_find(&V_pf_osfp_list, &fp,
211 	    PF_OSFP_MAXTTL_OFFSET)))
212 		return (&fpresult->fp_oses);
213 	return (NULL);
214 }
215 
216 /* Match a fingerprint ID against a list of OSes */
217 int
218 pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
219 {
220 	struct pf_osfp_entry *entry;
221 	int os_class, os_version, os_subtype;
222 	int en_class, en_version, en_subtype;
223 
224 	if (os == PF_OSFP_ANY)
225 		return (1);
226 	if (list == NULL) {
227 		DPFPRINTF("osfp no match against %x\n", os);
228 		return (os == PF_OSFP_UNKNOWN);
229 	}
230 	PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
231 	SLIST_FOREACH(entry, list, fp_entry) {
232 		PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
233 		if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
234 		    (os_version == PF_OSFP_ANY || en_version == os_version) &&
235 		    (os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
236 			DPFPRINTF("osfp matched %s %s %s  %x==%x\n",
237 			    entry->fp_class_nm, entry->fp_version_nm,
238 			    entry->fp_subtype_nm, os, entry->fp_os);
239 			return (1);
240 		}
241 	}
242 	DPFPRINTF("fingerprint 0x%x didn't match\n", os);
243 	return (0);
244 }
245 
246 /* Flush the fingerprint list */
247 void
248 pf_osfp_flush(void)
249 {
250 	struct pf_os_fingerprint *fp;
251 	struct pf_osfp_entry *entry;
252 
253 	while ((fp = SLIST_FIRST(&V_pf_osfp_list))) {
254 		SLIST_REMOVE_HEAD(&V_pf_osfp_list, fp_next);
255 		while ((entry = SLIST_FIRST(&fp->fp_oses))) {
256 			SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
257 			free(entry, M_PFOSFP);
258 		}
259 		free(fp, M_PFOSFP);
260 	}
261 }
262 
263 
264 /* Add a fingerprint */
265 int
266 pf_osfp_add(struct pf_osfp_ioctl *fpioc)
267 {
268 	struct pf_os_fingerprint *fp, fpadd;
269 	struct pf_osfp_entry *entry;
270 
271 	PF_RULES_WASSERT();
272 
273 	memset(&fpadd, 0, sizeof(fpadd));
274 	fpadd.fp_tcpopts = fpioc->fp_tcpopts;
275 	fpadd.fp_wsize = fpioc->fp_wsize;
276 	fpadd.fp_psize = fpioc->fp_psize;
277 	fpadd.fp_mss = fpioc->fp_mss;
278 	fpadd.fp_flags = fpioc->fp_flags;
279 	fpadd.fp_optcnt = fpioc->fp_optcnt;
280 	fpadd.fp_wscale = fpioc->fp_wscale;
281 	fpadd.fp_ttl = fpioc->fp_ttl;
282 
283 #if 0	/* XXX RYAN wants to fix logging */
284 	DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
285 	    "(TS=%s,M=%s%d,W=%s%d) %x\n",
286 	    fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
287 	    fpioc->fp_os.fp_subtype_nm,
288 	    (fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
289 	    (fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
290 	    (fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
291 	    (fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
292 	    fpadd.fp_wsize,
293 	    fpadd.fp_ttl,
294 	    (fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
295 	    (fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
296 	    (fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
297 	    fpadd.fp_psize,
298 	    (long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
299 	    (fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
300 	    (fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
301 	    (fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
302 	    fpadd.fp_mss,
303 	    (fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
304 	    (fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
305 	    fpadd.fp_wscale,
306 	    fpioc->fp_os.fp_os);
307 #endif
308 
309 	if ((fp = pf_osfp_find_exact(&V_pf_osfp_list, &fpadd))) {
310 		 SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
311 			if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
312 				return (EEXIST);
313 		}
314 		if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
315 		    == NULL)
316 			return (ENOMEM);
317 	} else {
318 		if ((fp = malloc(sizeof(*fp), M_PFOSFP, M_ZERO | M_NOWAIT))
319 		    == NULL)
320 			return (ENOMEM);
321 		fp->fp_tcpopts = fpioc->fp_tcpopts;
322 		fp->fp_wsize = fpioc->fp_wsize;
323 		fp->fp_psize = fpioc->fp_psize;
324 		fp->fp_mss = fpioc->fp_mss;
325 		fp->fp_flags = fpioc->fp_flags;
326 		fp->fp_optcnt = fpioc->fp_optcnt;
327 		fp->fp_wscale = fpioc->fp_wscale;
328 		fp->fp_ttl = fpioc->fp_ttl;
329 		SLIST_INIT(&fp->fp_oses);
330 		if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
331 		    == NULL) {
332 			free(fp, M_PFOSFP);
333 			return (ENOMEM);
334 		}
335 		pf_osfp_insert(&V_pf_osfp_list, fp);
336 	}
337 	memcpy(entry, &fpioc->fp_os, sizeof(*entry));
338 
339 	/* Make sure the strings are NUL terminated */
340 	entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
341 	entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
342 	entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
343 
344 	SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
345 
346 #ifdef PFDEBUG
347 	if ((fp = pf_osfp_validate()))
348 		printf("Invalid fingerprint list\n");
349 #endif /* PFDEBUG */
350 	return (0);
351 }
352 
353 
354 /* Find a fingerprint in the list */
355 static struct pf_os_fingerprint *
356 pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
357     u_int8_t ttldiff)
358 {
359 	struct pf_os_fingerprint *f;
360 
361 #define	MATCH_INT(_MOD, _DC, _field)					\
362 	if ((f->fp_flags & _DC) == 0) {					\
363 		if ((f->fp_flags & _MOD) == 0) {			\
364 			if (f->_field != find->_field)			\
365 				continue;				\
366 		} else {						\
367 			if (f->_field == 0 || find->_field % f->_field)	\
368 				continue;				\
369 		}							\
370 	}
371 
372 	SLIST_FOREACH(f, list, fp_next) {
373 		if (f->fp_tcpopts != find->fp_tcpopts ||
374 		    f->fp_optcnt != find->fp_optcnt ||
375 		    f->fp_ttl < find->fp_ttl ||
376 		    f->fp_ttl - find->fp_ttl > ttldiff ||
377 		    (f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
378 		    (find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
379 			continue;
380 
381 		MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
382 		MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
383 		MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
384 		if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
385 			if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
386 				if (find->fp_mss == 0)
387 					continue;
388 
389 /*
390  * Some "smart" NAT devices and DSL routers will tweak the MSS size and
391  * will set it to whatever is suitable for the link type.
392  */
393 #define	SMART_MSS	1460
394 				if ((find->fp_wsize % find->fp_mss ||
395 				    find->fp_wsize / find->fp_mss !=
396 				    f->fp_wsize) &&
397 				    (find->fp_wsize % SMART_MSS ||
398 				    find->fp_wsize / SMART_MSS !=
399 				    f->fp_wsize))
400 					continue;
401 			} else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
402 				if (find->fp_mss == 0)
403 					continue;
404 
405 #define	MTUOFF		(sizeof(struct ip) + sizeof(struct tcphdr))
406 #define	SMART_MTU	(SMART_MSS + MTUOFF)
407 				if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
408 				    find->fp_wsize / (find->fp_mss + MTUOFF) !=
409 				    f->fp_wsize) &&
410 				    (find->fp_wsize % SMART_MTU ||
411 				    find->fp_wsize / SMART_MTU !=
412 				    f->fp_wsize))
413 					continue;
414 			} else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
415 				if (f->fp_wsize == 0 || find->fp_wsize %
416 				    f->fp_wsize)
417 					continue;
418 			} else {
419 				if (f->fp_wsize != find->fp_wsize)
420 					continue;
421 			}
422 		}
423 		return (f);
424 	}
425 
426 	return (NULL);
427 }
428 
429 /* Find an exact fingerprint in the list */
430 static struct pf_os_fingerprint *
431 pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
432 {
433 	struct pf_os_fingerprint *f;
434 
435 	SLIST_FOREACH(f, list, fp_next) {
436 		if (f->fp_tcpopts == find->fp_tcpopts &&
437 		    f->fp_wsize == find->fp_wsize &&
438 		    f->fp_psize == find->fp_psize &&
439 		    f->fp_mss == find->fp_mss &&
440 		    f->fp_flags == find->fp_flags &&
441 		    f->fp_optcnt == find->fp_optcnt &&
442 		    f->fp_wscale == find->fp_wscale &&
443 		    f->fp_ttl == find->fp_ttl)
444 			return (f);
445 	}
446 
447 	return (NULL);
448 }
449 
450 /* Insert a fingerprint into the list */
451 static void
452 pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
453 {
454 	struct pf_os_fingerprint *f, *prev = NULL;
455 
456 	/* XXX need to go semi tree based.  can key on tcp options */
457 
458 	SLIST_FOREACH(f, list, fp_next)
459 		prev = f;
460 	if (prev)
461 		SLIST_INSERT_AFTER(prev, ins, fp_next);
462 	else
463 		SLIST_INSERT_HEAD(list, ins, fp_next);
464 }
465 
466 /* Fill a fingerprint by its number (from an ioctl) */
467 int
468 pf_osfp_get(struct pf_osfp_ioctl *fpioc)
469 {
470 	struct pf_os_fingerprint *fp;
471 	struct pf_osfp_entry *entry;
472 	int num = fpioc->fp_getnum;
473 	int i = 0;
474 
475 
476 	memset(fpioc, 0, sizeof(*fpioc));
477 	SLIST_FOREACH(fp, &V_pf_osfp_list, fp_next) {
478 		SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
479 			if (i++ == num) {
480 				fpioc->fp_mss = fp->fp_mss;
481 				fpioc->fp_wsize = fp->fp_wsize;
482 				fpioc->fp_flags = fp->fp_flags;
483 				fpioc->fp_psize = fp->fp_psize;
484 				fpioc->fp_ttl = fp->fp_ttl;
485 				fpioc->fp_wscale = fp->fp_wscale;
486 				fpioc->fp_getnum = num;
487 				memcpy(&fpioc->fp_os, entry,
488 				    sizeof(fpioc->fp_os));
489 				return (0);
490 			}
491 		}
492 	}
493 
494 	return (EBUSY);
495 }
496 
497 
498 #ifdef PFDEBUG
499 /* Validate that each signature is reachable */
500 static struct pf_os_fingerprint *
501 pf_osfp_validate(void)
502 {
503 	struct pf_os_fingerprint *f, *f2, find;
504 
505 	SLIST_FOREACH(f, &V_pf_osfp_list, fp_next) {
506 		memcpy(&find, f, sizeof(find));
507 
508 		/* We do a few MSS/th_win percolations to make things unique */
509 		if (find.fp_mss == 0)
510 			find.fp_mss = 128;
511 		if (f->fp_flags & PF_OSFP_WSIZE_MSS)
512 			find.fp_wsize *= find.fp_mss;
513 		else if (f->fp_flags & PF_OSFP_WSIZE_MTU)
514 			find.fp_wsize *= (find.fp_mss + 40);
515 		else if (f->fp_flags & PF_OSFP_WSIZE_MOD)
516 			find.fp_wsize *= 2;
517 		if (f != (f2 = pf_osfp_find(&V_pf_osfp_list, &find, 0))) {
518 			if (f2)
519 				printf("Found \"%s %s %s\" instead of "
520 				    "\"%s %s %s\"\n",
521 				    SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
522 				    SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
523 				    SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
524 				    SLIST_FIRST(&f->fp_oses)->fp_class_nm,
525 				    SLIST_FIRST(&f->fp_oses)->fp_version_nm,
526 				    SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
527 			else
528 				printf("Couldn't find \"%s %s %s\"\n",
529 				    SLIST_FIRST(&f->fp_oses)->fp_class_nm,
530 				    SLIST_FIRST(&f->fp_oses)->fp_version_nm,
531 				    SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
532 			return (f);
533 		}
534 	}
535 	return (NULL);
536 }
537 #endif /* PFDEBUG */
538