xref: /freebsd/sys/kgssapi/krb5/krb5_mech.c (revision aa0a1e58)
1 /*-
2  * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
3  * Authors: Doug Rabson <dfr@rabson.org>
4  * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
31 #include "opt_inet6.h"
32 
33 #include <sys/param.h>
34 #include <sys/kernel.h>
35 #include <sys/kobj.h>
36 #include <sys/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/mbuf.h>
39 #include <sys/module.h>
40 #include <sys/mutex.h>
41 #include <kgssapi/gssapi.h>
42 #include <kgssapi/gssapi_impl.h>
43 
44 #include "kgss_if.h"
45 #include "kcrypto.h"
46 
47 #define GSS_TOKEN_SENT_BY_ACCEPTOR	1
48 #define GSS_TOKEN_SEALED		2
49 #define GSS_TOKEN_ACCEPTOR_SUBKEY	4
50 
51 static gss_OID_desc krb5_mech_oid =
52 {9, (void *) "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02" };
53 
54 struct krb5_data {
55 	size_t		kd_length;
56 	void		*kd_data;
57 };
58 
59 struct krb5_keyblock {
60 	uint16_t	kk_type; /* encryption type */
61 	struct krb5_data kk_key; /* key data */
62 };
63 
64 struct krb5_address {
65 	uint16_t	ka_type;
66 	struct krb5_data ka_addr;
67 };
68 
69 /*
70  * The km_elem array is ordered so that the highest received sequence
71  * number is listed first.
72  */
73 struct krb5_msg_order {
74 	uint32_t		km_flags;
75 	uint32_t		km_start;
76 	uint32_t		km_length;
77 	uint32_t		km_jitter_window;
78 	uint32_t		km_first_seq;
79 	uint32_t		*km_elem;
80 };
81 
82 struct krb5_context {
83 	struct _gss_ctx_id_t	kc_common;
84 	struct mtx		kc_lock;
85 	uint32_t		kc_ac_flags;
86 	uint32_t		kc_ctx_flags;
87 	uint32_t		kc_more_flags;
88 #define LOCAL			1
89 #define OPEN			2
90 #define COMPAT_OLD_DES3		4
91 #define COMPAT_OLD_DES3_SELECTED 8
92 #define ACCEPTOR_SUBKEY		16
93 	struct krb5_address	kc_local_address;
94 	struct krb5_address	kc_remote_address;
95 	uint16_t		kc_local_port;
96 	uint16_t		kc_remote_port;
97 	struct krb5_keyblock	kc_keyblock;
98 	struct krb5_keyblock	kc_local_subkey;
99 	struct krb5_keyblock	kc_remote_subkey;
100 	volatile uint32_t	kc_local_seqnumber;
101 	uint32_t		kc_remote_seqnumber;
102 	uint32_t		kc_keytype;
103 	uint32_t		kc_cksumtype;
104 	struct krb5_data	kc_source_name;
105 	struct krb5_data	kc_target_name;
106 	uint32_t		kc_lifetime;
107 	struct krb5_msg_order	kc_msg_order;
108 	struct krb5_key_state	*kc_tokenkey;
109 	struct krb5_key_state	*kc_encryptkey;
110 	struct krb5_key_state	*kc_checksumkey;
111 
112 	struct krb5_key_state	*kc_send_seal_Ke;
113 	struct krb5_key_state	*kc_send_seal_Ki;
114 	struct krb5_key_state	*kc_send_seal_Kc;
115 	struct krb5_key_state	*kc_send_sign_Kc;
116 
117 	struct krb5_key_state	*kc_recv_seal_Ke;
118 	struct krb5_key_state	*kc_recv_seal_Ki;
119 	struct krb5_key_state	*kc_recv_seal_Kc;
120 	struct krb5_key_state	*kc_recv_sign_Kc;
121 };
122 
123 static uint16_t
124 get_uint16(const uint8_t **pp, size_t *lenp)
125 {
126 	const uint8_t *p = *pp;
127 	uint16_t v;
128 
129 	if (*lenp < 2)
130 		return (0);
131 
132 	v = (p[0] << 8) | p[1];
133 	*pp = p + 2;
134 	*lenp = *lenp - 2;
135 
136 	return (v);
137 }
138 
139 static uint32_t
140 get_uint32(const uint8_t **pp, size_t *lenp)
141 {
142 	const uint8_t *p = *pp;
143 	uint32_t v;
144 
145 	if (*lenp < 4)
146 		return (0);
147 
148 	v = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
149 	*pp = p + 4;
150 	*lenp = *lenp - 4;
151 
152 	return (v);
153 }
154 
155 static void
156 get_data(const uint8_t **pp, size_t *lenp, struct krb5_data *dp)
157 {
158 	size_t sz = get_uint32(pp, lenp);
159 
160 	dp->kd_length = sz;
161 	dp->kd_data = malloc(sz, M_GSSAPI, M_WAITOK);
162 
163 	if (*lenp < sz)
164 		sz = *lenp;
165 	bcopy(*pp, dp->kd_data, sz);
166 	(*pp) += sz;
167 	(*lenp) -= sz;
168 }
169 
170 static void
171 delete_data(struct krb5_data *dp)
172 {
173 	if (dp->kd_data) {
174 		free(dp->kd_data, M_GSSAPI);
175 		dp->kd_length = 0;
176 		dp->kd_data = NULL;
177 	}
178 }
179 
180 static void
181 get_address(const uint8_t **pp, size_t *lenp, struct krb5_address *ka)
182 {
183 
184 	ka->ka_type = get_uint16(pp, lenp);
185 	get_data(pp, lenp, &ka->ka_addr);
186 }
187 
188 static void
189 delete_address(struct krb5_address *ka)
190 {
191 	delete_data(&ka->ka_addr);
192 }
193 
194 static void
195 get_keyblock(const uint8_t **pp, size_t *lenp, struct krb5_keyblock *kk)
196 {
197 
198 	kk->kk_type = get_uint16(pp, lenp);
199 	get_data(pp, lenp, &kk->kk_key);
200 }
201 
202 static void
203 delete_keyblock(struct krb5_keyblock *kk)
204 {
205 	if (kk->kk_key.kd_data)
206 		bzero(kk->kk_key.kd_data, kk->kk_key.kd_length);
207 	delete_data(&kk->kk_key);
208 }
209 
210 static void
211 copy_key(struct krb5_keyblock *from, struct krb5_keyblock **to)
212 {
213 
214 	if (from->kk_key.kd_length)
215 		*to = from;
216 	else
217 		*to = NULL;
218 }
219 
220 /*
221  * Return non-zero if we are initiator.
222  */
223 static __inline int
224 is_initiator(struct krb5_context *kc)
225 {
226 	return (kc->kc_more_flags & LOCAL);
227 }
228 
229 /*
230  * Return non-zero if we are acceptor.
231  */
232 static __inline int
233 is_acceptor(struct krb5_context *kc)
234 {
235 	return !(kc->kc_more_flags & LOCAL);
236 }
237 
238 static void
239 get_initiator_subkey(struct krb5_context *kc, struct krb5_keyblock **kdp)
240 {
241 
242 	if (is_initiator(kc))
243 		copy_key(&kc->kc_local_subkey, kdp);
244 	else
245 		copy_key(&kc->kc_remote_subkey, kdp);
246 	if (!*kdp)
247 		copy_key(&kc->kc_keyblock, kdp);
248 }
249 
250 static void
251 get_acceptor_subkey(struct krb5_context *kc, struct krb5_keyblock **kdp)
252 {
253 
254 	if (is_initiator(kc))
255 		copy_key(&kc->kc_remote_subkey, kdp);
256 	else
257 		copy_key(&kc->kc_local_subkey, kdp);
258 }
259 
260 static OM_uint32
261 get_keys(struct krb5_context *kc)
262 {
263 	struct krb5_keyblock *keydata;
264 	struct krb5_encryption_class *ec;
265 	struct krb5_key_state *key;
266 	int etype;
267 
268 	keydata = NULL;
269 	get_acceptor_subkey(kc, &keydata);
270 	if (!keydata)
271 		if ((kc->kc_more_flags & ACCEPTOR_SUBKEY) == 0)
272 			get_initiator_subkey(kc, &keydata);
273 	if (!keydata)
274 		return (GSS_S_FAILURE);
275 
276 	/*
277 	 * GSS-API treats all DES etypes the same and all DES3 etypes
278 	 * the same.
279 	 */
280 	switch (keydata->kk_type) {
281 	case ETYPE_DES_CBC_CRC:
282 	case ETYPE_DES_CBC_MD4:
283 	case ETYPE_DES_CBC_MD5:
284 		etype = ETYPE_DES_CBC_CRC;
285 		break;
286 
287 	case ETYPE_DES3_CBC_MD5:
288 	case ETYPE_DES3_CBC_SHA1:
289 	case ETYPE_OLD_DES3_CBC_SHA1:
290 		etype = ETYPE_DES3_CBC_SHA1;
291 
292 	default:
293 		etype = keydata->kk_type;
294 	}
295 
296 	ec = krb5_find_encryption_class(etype);
297 	if (!ec)
298 		return (GSS_S_FAILURE);
299 
300 	key = krb5_create_key(ec);
301 	krb5_set_key(key, keydata->kk_key.kd_data);
302 	kc->kc_tokenkey = key;
303 
304 	switch (etype) {
305 	case ETYPE_DES_CBC_CRC:
306 	case ETYPE_ARCFOUR_HMAC_MD5:
307 	case ETYPE_ARCFOUR_HMAC_MD5_56: {
308 		/*
309 		 * Single DES and ARCFOUR uses a 'derived' key (XOR
310 		 * with 0xf0) for encrypting wrap tokens. The original
311 		 * key is used for checksums and sequence numbers.
312 		 */
313 		struct krb5_key_state *ekey;
314 		uint8_t *ekp, *kp;
315 		int i;
316 
317 		ekey = krb5_create_key(ec);
318 		ekp = ekey->ks_key;
319 		kp = key->ks_key;
320 		for (i = 0; i < ec->ec_keylen; i++)
321 			ekp[i] = kp[i] ^ 0xf0;
322 		krb5_set_key(ekey, ekp);
323 		kc->kc_encryptkey = ekey;
324 		refcount_acquire(&key->ks_refs);
325 		kc->kc_checksumkey = key;
326 		break;
327 	}
328 
329 	case ETYPE_DES3_CBC_SHA1:
330 		/*
331 		 * Triple DES uses a RFC 3961 style derived key with
332 		 * usage number KG_USAGE_SIGN for checksums. The
333 		 * original key is used for encryption and sequence
334 		 * numbers.
335 		 */
336 		kc->kc_checksumkey = krb5_get_checksum_key(key, KG_USAGE_SIGN);
337 		refcount_acquire(&key->ks_refs);
338 		kc->kc_encryptkey = key;
339 		break;
340 
341 	default:
342 		/*
343 		 * We need eight derived keys four for sending and
344 		 * four for receiving.
345 		 */
346 		if (is_initiator(kc)) {
347 			/*
348 			 * We are initiator.
349 			 */
350 			kc->kc_send_seal_Ke = krb5_get_encryption_key(key,
351 			    KG_USAGE_INITIATOR_SEAL);
352 			kc->kc_send_seal_Ki = krb5_get_integrity_key(key,
353 			    KG_USAGE_INITIATOR_SEAL);
354 			kc->kc_send_seal_Kc = krb5_get_checksum_key(key,
355 			    KG_USAGE_INITIATOR_SEAL);
356 			kc->kc_send_sign_Kc = krb5_get_checksum_key(key,
357 			    KG_USAGE_INITIATOR_SIGN);
358 
359 			kc->kc_recv_seal_Ke = krb5_get_encryption_key(key,
360 			    KG_USAGE_ACCEPTOR_SEAL);
361 			kc->kc_recv_seal_Ki = krb5_get_integrity_key(key,
362 			    KG_USAGE_ACCEPTOR_SEAL);
363 			kc->kc_recv_seal_Kc = krb5_get_checksum_key(key,
364 			    KG_USAGE_ACCEPTOR_SEAL);
365 			kc->kc_recv_sign_Kc = krb5_get_checksum_key(key,
366 			    KG_USAGE_ACCEPTOR_SIGN);
367 		} else {
368 			/*
369 			 * We are acceptor.
370 			 */
371 			kc->kc_send_seal_Ke = krb5_get_encryption_key(key,
372 			    KG_USAGE_ACCEPTOR_SEAL);
373 			kc->kc_send_seal_Ki = krb5_get_integrity_key(key,
374 			    KG_USAGE_ACCEPTOR_SEAL);
375 			kc->kc_send_seal_Kc = krb5_get_checksum_key(key,
376 			    KG_USAGE_ACCEPTOR_SEAL);
377 			kc->kc_send_sign_Kc = krb5_get_checksum_key(key,
378 			    KG_USAGE_ACCEPTOR_SIGN);
379 
380 			kc->kc_recv_seal_Ke = krb5_get_encryption_key(key,
381 			    KG_USAGE_INITIATOR_SEAL);
382 			kc->kc_recv_seal_Ki = krb5_get_integrity_key(key,
383 			    KG_USAGE_INITIATOR_SEAL);
384 			kc->kc_recv_seal_Kc = krb5_get_checksum_key(key,
385 			    KG_USAGE_INITIATOR_SEAL);
386 			kc->kc_recv_sign_Kc = krb5_get_checksum_key(key,
387 			    KG_USAGE_INITIATOR_SIGN);
388 		}
389 		break;
390 	}
391 
392 	return (GSS_S_COMPLETE);
393 }
394 
395 static void
396 krb5_init(gss_ctx_id_t ctx)
397 {
398 	struct krb5_context *kc = (struct krb5_context *)ctx;
399 
400 	mtx_init(&kc->kc_lock, "krb5 gss lock", NULL, MTX_DEF);
401 }
402 
403 static OM_uint32
404 krb5_import(gss_ctx_id_t ctx,
405     enum sec_context_format format,
406     const gss_buffer_t context_token)
407 {
408 	struct krb5_context *kc = (struct krb5_context *)ctx;
409 	OM_uint32 res;
410 	const uint8_t *p = (const uint8_t *) context_token->value;
411 	size_t len = context_token->length;
412 	uint32_t flags;
413 	int i;
414 
415 	/*
416 	 * We support heimdal 0.6 and heimdal 1.1
417 	 */
418 	if (format != KGSS_HEIMDAL_0_6 && format != KGSS_HEIMDAL_1_1)
419 		return (GSS_S_DEFECTIVE_TOKEN);
420 
421 #define SC_LOCAL_ADDRESS	1
422 #define SC_REMOTE_ADDRESS	2
423 #define SC_KEYBLOCK		4
424 #define SC_LOCAL_SUBKEY		8
425 #define SC_REMOTE_SUBKEY	16
426 
427 	/*
428 	 * Ensure that the token starts with krb5 oid.
429 	 */
430 	if (p[0] != 0x00 || p[1] != krb5_mech_oid.length
431 	    || len < krb5_mech_oid.length + 2
432 	    || bcmp(krb5_mech_oid.elements, p + 2,
433 		krb5_mech_oid.length))
434 		return (GSS_S_DEFECTIVE_TOKEN);
435 	p += krb5_mech_oid.length + 2;
436 	len -= krb5_mech_oid.length + 2;
437 
438 	flags = get_uint32(&p, &len);
439 	kc->kc_ac_flags = get_uint32(&p, &len);
440 	if (flags & SC_LOCAL_ADDRESS)
441 		get_address(&p, &len, &kc->kc_local_address);
442 	if (flags & SC_REMOTE_ADDRESS)
443 		get_address(&p, &len, &kc->kc_remote_address);
444 	kc->kc_local_port = get_uint16(&p, &len);
445 	kc->kc_remote_port = get_uint16(&p, &len);
446 	if (flags & SC_KEYBLOCK)
447 		get_keyblock(&p, &len, &kc->kc_keyblock);
448 	if (flags & SC_LOCAL_SUBKEY)
449 		get_keyblock(&p, &len, &kc->kc_local_subkey);
450 	if (flags & SC_REMOTE_SUBKEY)
451 		get_keyblock(&p, &len, &kc->kc_remote_subkey);
452 	kc->kc_local_seqnumber = get_uint32(&p, &len);
453 	kc->kc_remote_seqnumber = get_uint32(&p, &len);
454 	kc->kc_keytype = get_uint32(&p, &len);
455 	kc->kc_cksumtype = get_uint32(&p, &len);
456 	get_data(&p, &len, &kc->kc_source_name);
457 	get_data(&p, &len, &kc->kc_target_name);
458 	kc->kc_ctx_flags = get_uint32(&p, &len);
459 	kc->kc_more_flags = get_uint32(&p, &len);
460 	kc->kc_lifetime = get_uint32(&p, &len);
461 	/*
462 	 * Heimdal 1.1 adds the message order stuff.
463 	 */
464 	if (format == KGSS_HEIMDAL_1_1) {
465 		kc->kc_msg_order.km_flags = get_uint32(&p, &len);
466 		kc->kc_msg_order.km_start = get_uint32(&p, &len);
467 		kc->kc_msg_order.km_length = get_uint32(&p, &len);
468 		kc->kc_msg_order.km_jitter_window = get_uint32(&p, &len);
469 		kc->kc_msg_order.km_first_seq = get_uint32(&p, &len);
470 		kc->kc_msg_order.km_elem =
471 			malloc(kc->kc_msg_order.km_jitter_window * sizeof(uint32_t),
472 			    M_GSSAPI, M_WAITOK);
473 		for (i = 0; i < kc->kc_msg_order.km_jitter_window; i++)
474 			kc->kc_msg_order.km_elem[i] = get_uint32(&p, &len);
475 	} else {
476 		kc->kc_msg_order.km_flags = 0;
477 	}
478 
479 	res = get_keys(kc);
480 	if (GSS_ERROR(res))
481 		return (res);
482 
483 	/*
484 	 * We don't need these anymore.
485 	 */
486 	delete_keyblock(&kc->kc_keyblock);
487 	delete_keyblock(&kc->kc_local_subkey);
488 	delete_keyblock(&kc->kc_remote_subkey);
489 
490 	return (GSS_S_COMPLETE);
491 }
492 
493 static void
494 krb5_delete(gss_ctx_id_t ctx, gss_buffer_t output_token)
495 {
496 	struct krb5_context *kc = (struct krb5_context *)ctx;
497 
498 	delete_address(&kc->kc_local_address);
499 	delete_address(&kc->kc_remote_address);
500 	delete_keyblock(&kc->kc_keyblock);
501 	delete_keyblock(&kc->kc_local_subkey);
502 	delete_keyblock(&kc->kc_remote_subkey);
503 	delete_data(&kc->kc_source_name);
504 	delete_data(&kc->kc_target_name);
505 	if (kc->kc_msg_order.km_elem)
506 		free(kc->kc_msg_order.km_elem, M_GSSAPI);
507 	if (output_token) {
508 		output_token->length = 0;
509 		output_token->value = NULL;
510 	}
511 	if (kc->kc_tokenkey) {
512 		krb5_free_key(kc->kc_tokenkey);
513 		if (kc->kc_encryptkey) {
514 			krb5_free_key(kc->kc_encryptkey);
515 			krb5_free_key(kc->kc_checksumkey);
516 		} else {
517 			krb5_free_key(kc->kc_send_seal_Ke);
518 			krb5_free_key(kc->kc_send_seal_Ki);
519 			krb5_free_key(kc->kc_send_seal_Kc);
520 			krb5_free_key(kc->kc_send_sign_Kc);
521 			krb5_free_key(kc->kc_recv_seal_Ke);
522 			krb5_free_key(kc->kc_recv_seal_Ki);
523 			krb5_free_key(kc->kc_recv_seal_Kc);
524 			krb5_free_key(kc->kc_recv_sign_Kc);
525 		}
526 	}
527 	mtx_destroy(&kc->kc_lock);
528 }
529 
530 static gss_OID
531 krb5_mech_type(gss_ctx_id_t ctx)
532 {
533 
534 	return (&krb5_mech_oid);
535 }
536 
537 /*
538  * Make a token with the given type and length (the length includes
539  * the TOK_ID), initialising the token header appropriately. Return a
540  * pointer to the TOK_ID of the token.  A new mbuf is allocated with
541  * the framing header plus hlen bytes of space.
542  *
543  * Format is as follows:
544  *
545  *	0x60			[APPLICATION 0] SEQUENCE
546  *	DER encoded length	length of oid + type + inner token length
547  *	0x06 NN <oid data>	OID of mechanism type
548  *	TT TT			TOK_ID
549  *	<inner token>		data for inner token
550  *
551  * 1:		der encoded length
552  */
553 static void *
554 krb5_make_token(char tok_id[2], size_t hlen, size_t len, struct mbuf **mp)
555 {
556 	size_t inside_len, len_len, tlen;
557 	gss_OID oid = &krb5_mech_oid;
558 	struct mbuf *m;
559 	uint8_t *p;
560 
561 	inside_len = 2 + oid->length + len;
562 	if (inside_len < 128)
563 		len_len = 1;
564 	else if (inside_len < 0x100)
565 		len_len = 2;
566 	else if (inside_len < 0x10000)
567 		len_len = 3;
568 	else if (inside_len < 0x1000000)
569 		len_len = 4;
570 	else
571 		len_len = 5;
572 
573 	tlen = 1 + len_len + 2 + oid->length + hlen;
574 	KASSERT(tlen <= MLEN, ("token head too large"));
575 	MGET(m, M_WAITOK, MT_DATA);
576 	M_ALIGN(m, tlen);
577 	m->m_len = tlen;
578 
579 	p = (uint8_t *) m->m_data;
580 	*p++ = 0x60;
581 	switch (len_len) {
582 	case 1:
583 		*p++ = inside_len;
584 		break;
585 	case 2:
586 		*p++ = 0x81;
587 		*p++ = inside_len;
588 		break;
589 	case 3:
590 		*p++ = 0x82;
591 		*p++ = inside_len >> 8;
592 		*p++ = inside_len;
593 		break;
594 	case 4:
595 		*p++ = 0x83;
596 		*p++ = inside_len >> 16;
597 		*p++ = inside_len >> 8;
598 		*p++ = inside_len;
599 		break;
600 	case 5:
601 		*p++ = 0x84;
602 		*p++ = inside_len >> 24;
603 		*p++ = inside_len >> 16;
604 		*p++ = inside_len >> 8;
605 		*p++ = inside_len;
606 		break;
607 	}
608 
609 	*p++ = 0x06;
610 	*p++ = oid->length;
611 	bcopy(oid->elements, p, oid->length);
612 	p += oid->length;
613 
614 	p[0] = tok_id[0];
615 	p[1] = tok_id[1];
616 
617 	*mp = m;
618 
619 	return (p);
620 }
621 
622 /*
623  * Verify a token, checking the inner token length and mechanism oid.
624  * pointer to the first byte of the TOK_ID. The length of the
625  * encapsulated data is checked to be at least len bytes; the actual
626  * length of the encapsulated data (including TOK_ID) is returned in
627  * *encap_len.
628  *
629  * If can_pullup is TRUE and the token header is fragmented, we will
630  * rearrange it.
631  *
632  * Format is as follows:
633  *
634  *	0x60			[APPLICATION 0] SEQUENCE
635  *	DER encoded length	length of oid + type + inner token length
636  *	0x06 NN <oid data>	OID of mechanism type
637  *	TT TT			TOK_ID
638  *	<inner token>		data for inner token
639  *
640  * 1:		der encoded length
641  */
642 static void *
643 krb5_verify_token(char tok_id[2], size_t len, struct mbuf **mp,
644     size_t *encap_len, bool_t can_pullup)
645 {
646 	struct mbuf *m;
647 	size_t tlen, hlen, len_len, inside_len;
648 	gss_OID oid = &krb5_mech_oid;
649 	uint8_t *p;
650 
651 	m = *mp;
652 	tlen = m_length(m, NULL);
653 	if (tlen < 2)
654 		return (NULL);
655 
656 	/*
657 	 * Ensure that at least the framing part of the token is
658 	 * contigous.
659 	 */
660 	if (m->m_len < 2) {
661 		if (can_pullup)
662 			*mp = m = m_pullup(m, 2);
663 		else
664 			return (NULL);
665 	}
666 
667 	p = m->m_data;
668 
669 	if (*p++ != 0x60)
670 		return (NULL);
671 
672 	if (*p < 0x80) {
673 		inside_len = *p++;
674 		len_len = 1;
675 	} else {
676 		/*
677 		 * Ensure there is enough space for the DER encoded length.
678 		 */
679 		len_len = (*p & 0x7f) + 1;
680 		if (tlen < len_len + 1)
681 			return (NULL);
682 		if (m->m_len < len_len + 1) {
683 			if (can_pullup)
684 				*mp = m = m_pullup(m, len_len + 1);
685 			else
686 				return (NULL);
687 			p = m->m_data + 1;
688 		}
689 
690 		switch (*p++) {
691 		case 0x81:
692 			inside_len = *p++;
693 			break;
694 
695 		case 0x82:
696 			inside_len = (p[0] << 8) | p[1];
697 			p += 2;
698 			break;
699 
700 		case 0x83:
701 			inside_len = (p[0] << 16) | (p[1] << 8) | p[2];
702 			p += 3;
703 			break;
704 
705 		case 0x84:
706 			inside_len = (p[0] << 24) | (p[1] << 16)
707 				| (p[2] << 8) | p[3];
708 			p += 4;
709 			break;
710 
711 		default:
712 			return (NULL);
713 		}
714 	}
715 
716 	if (tlen != inside_len + len_len + 1)
717 		return (NULL);
718 	if (inside_len < 2 + oid->length + len)
719 		return (NULL);
720 
721 	/*
722 	 * Now that we know the value of len_len, we can pullup the
723 	 * whole header. The header is 1 + len_len + 2 + oid->length +
724 	 * len bytes.
725 	 */
726 	hlen = 1 + len_len + 2 + oid->length + len;
727 	if (m->m_len < hlen) {
728 		if (can_pullup)
729 			*mp = m = m_pullup(m, hlen);
730 		else
731 			return (NULL);
732 		p = m->m_data + 1 + len_len;
733 	}
734 
735 	if (*p++ != 0x06)
736 		return (NULL);
737 	if (*p++ != oid->length)
738 		return (NULL);
739 	if (bcmp(oid->elements, p, oid->length))
740 		return (NULL);
741 	p += oid->length;
742 
743 	if (p[0] != tok_id[0])
744 		return (NULL);
745 
746 	if (p[1] != tok_id[1])
747 		return (NULL);
748 
749 	*encap_len = inside_len - 2 - oid->length;
750 
751 	return (p);
752 }
753 
754 static void
755 krb5_insert_seq(struct krb5_msg_order *mo, uint32_t seq, int index)
756 {
757 	int i;
758 
759 	if (mo->km_length < mo->km_jitter_window)
760 		mo->km_length++;
761 
762 	for (i = mo->km_length - 1; i > index; i--)
763 		mo->km_elem[i] = mo->km_elem[i - 1];
764 	mo->km_elem[index] = seq;
765 }
766 
767 /*
768  * Check sequence numbers according to RFC 2743 section 1.2.3.
769  */
770 static OM_uint32
771 krb5_sequence_check(struct krb5_context *kc, uint32_t seq)
772 {
773 	OM_uint32 res = GSS_S_FAILURE;
774 	struct krb5_msg_order *mo = &kc->kc_msg_order;
775 	int check_sequence = mo->km_flags & GSS_C_SEQUENCE_FLAG;
776 	int check_replay = mo->km_flags & GSS_C_REPLAY_FLAG;
777 	int i;
778 
779 	mtx_lock(&kc->kc_lock);
780 
781 	/*
782 	 * Message is in-sequence with no gap.
783 	 */
784 	if (mo->km_length == 0 || seq == mo->km_elem[0] + 1) {
785 		/*
786 		 * This message is received in-sequence with no gaps.
787 		 */
788 		krb5_insert_seq(mo, seq, 0);
789 		res = GSS_S_COMPLETE;
790 		goto out;
791 	}
792 
793 	if (seq > mo->km_elem[0]) {
794 		/*
795 		 * This message is received in-sequence with a gap.
796 		 */
797 		krb5_insert_seq(mo, seq, 0);
798 		if (check_sequence)
799 			res = GSS_S_GAP_TOKEN;
800 		else
801 			res = GSS_S_COMPLETE;
802 		goto out;
803 	}
804 
805 	if (seq < mo->km_elem[mo->km_length - 1]) {
806 		if (check_replay && !check_sequence)
807 			res = GSS_S_OLD_TOKEN;
808 		else
809 			res = GSS_S_UNSEQ_TOKEN;
810 		goto out;
811 	}
812 
813 	for (i = 0; i < mo->km_length; i++) {
814 		if (mo->km_elem[i] == seq) {
815 			res = GSS_S_DUPLICATE_TOKEN;
816 			goto out;
817 		}
818 		if (mo->km_elem[i] < seq) {
819 			/*
820 			 * We need to insert this seq here,
821 			 */
822 			krb5_insert_seq(mo, seq, i);
823 			if (check_replay && !check_sequence)
824 				res = GSS_S_COMPLETE;
825 			else
826 				res = GSS_S_UNSEQ_TOKEN;
827 			goto out;
828 		}
829 	}
830 
831 out:
832 	mtx_unlock(&kc->kc_lock);
833 
834 	return (res);
835 }
836 
837 static uint8_t sgn_alg_des_md5[] = { 0x00, 0x00 };
838 static uint8_t seal_alg_des[] = { 0x00, 0x00 };
839 static uint8_t sgn_alg_des3_sha1[] = { 0x04, 0x00 };
840 static uint8_t seal_alg_des3[] = { 0x02, 0x00 };
841 static uint8_t seal_alg_rc4[] = { 0x10, 0x00 };
842 static uint8_t sgn_alg_hmac_md5[] = { 0x11, 0x00 };
843 
844 /*
845  * Return the size of the inner token given the use of the key's
846  * encryption class. For wrap tokens, the length of the padded
847  * plaintext will be added to this.
848  */
849 static size_t
850 token_length(struct krb5_key_state *key)
851 {
852 
853 	return (16 + key->ks_class->ec_checksumlen);
854 }
855 
856 static OM_uint32
857 krb5_get_mic_old(struct krb5_context *kc, struct mbuf *m,
858     struct mbuf **micp, uint8_t sgn_alg[2])
859 {
860 	struct mbuf *mlast, *mic, *tm;
861 	uint8_t *p, dir;
862 	size_t tlen, mlen, cklen;
863 	uint32_t seq;
864 	char buf[8];
865 
866 	mlen = m_length(m, &mlast);
867 
868 	tlen = token_length(kc->kc_tokenkey);
869 	p = krb5_make_token("\x01\x01", tlen, tlen, &mic);
870 	p += 2;			/* TOK_ID */
871 	*p++ = sgn_alg[0];	/* SGN_ALG */
872 	*p++ = sgn_alg[1];
873 
874 	*p++ = 0xff;		/* filler */
875 	*p++ = 0xff;
876 	*p++ = 0xff;
877 	*p++ = 0xff;
878 
879 	/*
880 	 * SGN_CKSUM:
881 	 *
882 	 * Calculate the keyed checksum of the token header plus the
883 	 * message.
884 	 */
885 	cklen = kc->kc_checksumkey->ks_class->ec_checksumlen;
886 
887 	mic->m_len = p - (uint8_t *) mic->m_data;
888 	mic->m_next = m;
889 	MGET(tm, M_WAITOK, MT_DATA);
890 	tm->m_len = cklen;
891 	mlast->m_next = tm;
892 
893 	krb5_checksum(kc->kc_checksumkey, 15, mic, mic->m_len - 8,
894 	    8 + mlen, cklen);
895 	bcopy(tm->m_data, p + 8, cklen);
896 	mic->m_next = NULL;
897 	mlast->m_next = NULL;
898 	m_free(tm);
899 
900 	/*
901 	 * SND_SEQ:
902 	 *
903 	 * Take the four bytes of the sequence number least
904 	 * significant first followed by four bytes of direction
905 	 * marker (zero for initiator and 0xff for acceptor). Encrypt
906 	 * that data using the SGN_CKSUM as IV. Note: ARC4 wants the
907 	 * sequence number big-endian.
908 	 */
909 	seq = atomic_fetchadd_32(&kc->kc_local_seqnumber, 1);
910 	if (sgn_alg[0] == 0x11) {
911 		p[0] = (seq >> 24);
912 		p[1] = (seq >> 16);
913 		p[2] = (seq >> 8);
914 		p[3] = (seq >> 0);
915 	} else {
916 		p[0] = (seq >> 0);
917 		p[1] = (seq >> 8);
918 		p[2] = (seq >> 16);
919 		p[3] = (seq >> 24);
920 	}
921 	if (is_initiator(kc)) {
922 		dir = 0;
923 	} else {
924 		dir = 0xff;
925 	}
926 	p[4] = dir;
927 	p[5] = dir;
928 	p[6] = dir;
929 	p[7] = dir;
930 	bcopy(p + 8, buf, 8);
931 
932 	/*
933 	 * Set the mic buffer to its final size so that the encrypt
934 	 * can see the SND_SEQ part.
935 	 */
936 	mic->m_len += 8 + cklen;
937 	krb5_encrypt(kc->kc_tokenkey, mic, mic->m_len - cklen - 8, 8, buf, 8);
938 
939 	*micp = mic;
940 	return (GSS_S_COMPLETE);
941 }
942 
943 static OM_uint32
944 krb5_get_mic_new(struct krb5_context *kc,  struct mbuf *m,
945     struct mbuf **micp)
946 {
947 	struct krb5_key_state *key = kc->kc_send_sign_Kc;
948 	struct mbuf *mlast, *mic;
949 	uint8_t *p;
950 	int flags;
951 	size_t mlen, cklen;
952 	uint32_t seq;
953 
954 	mlen = m_length(m, &mlast);
955 	cklen = key->ks_class->ec_checksumlen;
956 
957 	KASSERT(16 + cklen <= MLEN, ("checksum too large for an mbuf"));
958 	MGET(mic, M_WAITOK, MT_DATA);
959 	M_ALIGN(mic, 16 + cklen);
960 	mic->m_len = 16 + cklen;
961 	p = mic->m_data;
962 
963 	/* TOK_ID */
964 	p[0] = 0x04;
965 	p[1] = 0x04;
966 
967 	/* Flags */
968 	flags = 0;
969 	if (is_acceptor(kc))
970 		flags |= GSS_TOKEN_SENT_BY_ACCEPTOR;
971 	if (kc->kc_more_flags & ACCEPTOR_SUBKEY)
972 		flags |= GSS_TOKEN_ACCEPTOR_SUBKEY;
973 	p[2] = flags;
974 
975 	/* Filler */
976 	p[3] = 0xff;
977 	p[4] = 0xff;
978 	p[5] = 0xff;
979 	p[6] = 0xff;
980 	p[7] = 0xff;
981 
982 	/* SND_SEQ */
983 	p[8] = 0;
984 	p[9] = 0;
985 	p[10] = 0;
986 	p[11] = 0;
987 	seq = atomic_fetchadd_32(&kc->kc_local_seqnumber, 1);
988 	p[12] = (seq >> 24);
989 	p[13] = (seq >> 16);
990 	p[14] = (seq >> 8);
991 	p[15] = (seq >> 0);
992 
993 	/*
994 	 * SGN_CKSUM:
995 	 *
996 	 * Calculate the keyed checksum of the message plus the first
997 	 * 16 bytes of the token header.
998 	 */
999 	mlast->m_next = mic;
1000 	krb5_checksum(key, 0, m, 0, mlen + 16, cklen);
1001 	mlast->m_next = NULL;
1002 
1003 	*micp = mic;
1004 	return (GSS_S_COMPLETE);
1005 }
1006 
1007 static OM_uint32
1008 krb5_get_mic(gss_ctx_id_t ctx, OM_uint32 *minor_status,
1009     gss_qop_t qop_req, struct mbuf *m, struct mbuf **micp)
1010 {
1011 	struct krb5_context *kc = (struct krb5_context *)ctx;
1012 
1013 	*minor_status = 0;
1014 
1015 	if (qop_req != GSS_C_QOP_DEFAULT)
1016 		return (GSS_S_BAD_QOP);
1017 
1018 	if (time_uptime > kc->kc_lifetime)
1019 		return (GSS_S_CONTEXT_EXPIRED);
1020 
1021 	switch (kc->kc_tokenkey->ks_class->ec_type) {
1022 	case ETYPE_DES_CBC_CRC:
1023 		return (krb5_get_mic_old(kc, m, micp, sgn_alg_des_md5));
1024 
1025 	case ETYPE_DES3_CBC_SHA1:
1026 		return (krb5_get_mic_old(kc, m, micp, sgn_alg_des3_sha1));
1027 
1028 	case ETYPE_ARCFOUR_HMAC_MD5:
1029 	case ETYPE_ARCFOUR_HMAC_MD5_56:
1030 		return (krb5_get_mic_old(kc, m, micp, sgn_alg_hmac_md5));
1031 
1032 	default:
1033 		return (krb5_get_mic_new(kc, m, micp));
1034 	}
1035 
1036 	return (GSS_S_FAILURE);
1037 }
1038 
1039 static OM_uint32
1040 krb5_verify_mic_old(struct krb5_context *kc, struct mbuf *m, struct mbuf *mic,
1041     uint8_t sgn_alg[2])
1042 {
1043 	struct mbuf *mlast, *tm;
1044 	uint8_t *p, *tp, dir;
1045 	size_t mlen, tlen, elen, miclen;
1046 	size_t cklen;
1047 	uint32_t seq;
1048 
1049 	mlen = m_length(m, &mlast);
1050 
1051 	tlen = token_length(kc->kc_tokenkey);
1052 	p = krb5_verify_token("\x01\x01", tlen, &mic, &elen, FALSE);
1053 	if (!p)
1054 		return (GSS_S_DEFECTIVE_TOKEN);
1055 #if 0
1056 	/*
1057 	 * Disable this check - heimdal-1.1 generates DES3 MIC tokens
1058 	 * that are 2 bytes too big.
1059 	 */
1060 	if (elen != tlen)
1061 		return (GSS_S_DEFECTIVE_TOKEN);
1062 #endif
1063 	/* TOK_ID */
1064 	p += 2;
1065 
1066 	/* SGN_ALG */
1067 	if (p[0] != sgn_alg[0] || p[1] != sgn_alg[1])
1068 		return (GSS_S_DEFECTIVE_TOKEN);
1069 	p += 2;
1070 
1071 	if (p[0] != 0xff || p[1] != 0xff || p[2] != 0xff || p[3] != 0xff)
1072 		return (GSS_S_DEFECTIVE_TOKEN);
1073 	p += 4;
1074 
1075 	/*
1076 	 * SGN_CKSUM:
1077 	 *
1078 	 * Calculate the keyed checksum of the token header plus the
1079 	 * message.
1080 	 */
1081 	cklen = kc->kc_checksumkey->ks_class->ec_checksumlen;
1082 	miclen = mic->m_len;
1083 	mic->m_len = p - (uint8_t *) mic->m_data;
1084 	mic->m_next = m;
1085 	MGET(tm, M_WAITOK, MT_DATA);
1086 	tm->m_len = cklen;
1087 	mlast->m_next = tm;
1088 
1089 	krb5_checksum(kc->kc_checksumkey, 15, mic, mic->m_len - 8,
1090 	    8 + mlen, cklen);
1091 	mic->m_next = NULL;
1092 	mlast->m_next = NULL;
1093 	if (bcmp(tm->m_data, p + 8, cklen)) {
1094 		m_free(tm);
1095 		return (GSS_S_BAD_SIG);
1096 	}
1097 
1098 	/*
1099 	 * SND_SEQ:
1100 	 *
1101 	 * Take the four bytes of the sequence number least
1102 	 * significant first followed by four bytes of direction
1103 	 * marker (zero for initiator and 0xff for acceptor). Encrypt
1104 	 * that data using the SGN_CKSUM as IV.  Note: ARC4 wants the
1105 	 * sequence number big-endian.
1106 	 */
1107 	bcopy(p, tm->m_data, 8);
1108 	tm->m_len = 8;
1109 	krb5_decrypt(kc->kc_tokenkey, tm, 0, 8, p + 8, 8);
1110 
1111 	tp = tm->m_data;
1112 	if (sgn_alg[0] == 0x11) {
1113 		seq = tp[3] | (tp[2] << 8) | (tp[1] << 16) | (tp[0] << 24);
1114 	} else {
1115 		seq = tp[0] | (tp[1] << 8) | (tp[2] << 16) | (tp[3] << 24);
1116 	}
1117 
1118 	if (is_initiator(kc)) {
1119 		dir = 0xff;
1120 	} else {
1121 		dir = 0;
1122 	}
1123 	if (tp[4] != dir || tp[5] != dir || tp[6] != dir || tp[7] != dir) {
1124 		m_free(tm);
1125 		return (GSS_S_DEFECTIVE_TOKEN);
1126 	}
1127 	m_free(tm);
1128 
1129 	if (kc->kc_msg_order.km_flags &
1130 		(GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG)) {
1131 		return (krb5_sequence_check(kc, seq));
1132 	}
1133 
1134 	return (GSS_S_COMPLETE);
1135 }
1136 
1137 static OM_uint32
1138 krb5_verify_mic_new(struct krb5_context *kc, struct mbuf *m, struct mbuf *mic)
1139 {
1140 	OM_uint32 res;
1141 	struct krb5_key_state *key = kc->kc_recv_sign_Kc;
1142 	struct mbuf *mlast;
1143 	uint8_t *p;
1144 	int flags;
1145 	size_t mlen, cklen;
1146 	char buf[32];
1147 
1148 	mlen = m_length(m, &mlast);
1149 	cklen = key->ks_class->ec_checksumlen;
1150 
1151 	KASSERT(mic->m_next == NULL, ("MIC should be contiguous"));
1152 	if (mic->m_len != 16 + cklen)
1153 		return (GSS_S_DEFECTIVE_TOKEN);
1154 	p = mic->m_data;
1155 
1156 	/* TOK_ID */
1157 	if (p[0] != 0x04)
1158 		return (GSS_S_DEFECTIVE_TOKEN);
1159 	if (p[1] != 0x04)
1160 		return (GSS_S_DEFECTIVE_TOKEN);
1161 
1162 	/* Flags */
1163 	flags = 0;
1164 	if (is_initiator(kc))
1165 		flags |= GSS_TOKEN_SENT_BY_ACCEPTOR;
1166 	if (kc->kc_more_flags & ACCEPTOR_SUBKEY)
1167 		flags |= GSS_TOKEN_ACCEPTOR_SUBKEY;
1168 	if (p[2] != flags)
1169 		return (GSS_S_DEFECTIVE_TOKEN);
1170 
1171 	/* Filler */
1172 	if (p[3] != 0xff)
1173 		return (GSS_S_DEFECTIVE_TOKEN);
1174 	if (p[4] != 0xff)
1175 		return (GSS_S_DEFECTIVE_TOKEN);
1176 	if (p[5] != 0xff)
1177 		return (GSS_S_DEFECTIVE_TOKEN);
1178 	if (p[6] != 0xff)
1179 		return (GSS_S_DEFECTIVE_TOKEN);
1180 	if (p[7] != 0xff)
1181 		return (GSS_S_DEFECTIVE_TOKEN);
1182 
1183 	/* SND_SEQ */
1184 	if (kc->kc_msg_order.km_flags &
1185 		(GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG)) {
1186 		uint32_t seq;
1187 		if (p[8] || p[9] || p[10] || p[11]) {
1188 			res = GSS_S_UNSEQ_TOKEN;
1189 		} else {
1190 			seq = (p[12] << 24) | (p[13] << 16)
1191 				| (p[14] << 8) | p[15];
1192 			res = krb5_sequence_check(kc, seq);
1193 		}
1194 		if (GSS_ERROR(res))
1195 			return (res);
1196 	} else {
1197 		res = GSS_S_COMPLETE;
1198 	}
1199 
1200 	/*
1201 	 * SGN_CKSUM:
1202 	 *
1203 	 * Calculate the keyed checksum of the message plus the first
1204 	 * 16 bytes of the token header.
1205 	 */
1206 	m_copydata(mic, 16, cklen, buf);
1207 	mlast->m_next = mic;
1208 	krb5_checksum(key, 0, m, 0, mlen + 16, cklen);
1209 	mlast->m_next = NULL;
1210 	if (bcmp(buf, p + 16, cklen)) {
1211 		return (GSS_S_BAD_SIG);
1212 	}
1213 
1214 	return (GSS_S_COMPLETE);
1215 }
1216 
1217 static OM_uint32
1218 krb5_verify_mic(gss_ctx_id_t ctx, OM_uint32 *minor_status,
1219     struct mbuf *m, struct mbuf *mic, gss_qop_t *qop_state)
1220 {
1221 	struct krb5_context *kc = (struct krb5_context *)ctx;
1222 
1223 	*minor_status = 0;
1224 	if (qop_state)
1225 		*qop_state = GSS_C_QOP_DEFAULT;
1226 
1227 	if (time_uptime > kc->kc_lifetime)
1228 		return (GSS_S_CONTEXT_EXPIRED);
1229 
1230 	switch (kc->kc_tokenkey->ks_class->ec_type) {
1231 	case ETYPE_DES_CBC_CRC:
1232 		return (krb5_verify_mic_old(kc, m, mic, sgn_alg_des_md5));
1233 
1234 	case ETYPE_ARCFOUR_HMAC_MD5:
1235 	case ETYPE_ARCFOUR_HMAC_MD5_56:
1236 		return (krb5_verify_mic_old(kc, m, mic, sgn_alg_hmac_md5));
1237 
1238 	case ETYPE_DES3_CBC_SHA1:
1239 		return (krb5_verify_mic_old(kc, m, mic, sgn_alg_des3_sha1));
1240 
1241 	default:
1242 		return (krb5_verify_mic_new(kc, m, mic));
1243 	}
1244 
1245 	return (GSS_S_FAILURE);
1246 }
1247 
1248 static OM_uint32
1249 krb5_wrap_old(struct krb5_context *kc, int conf_req_flag,
1250     struct mbuf **mp, int *conf_state,
1251     uint8_t sgn_alg[2], uint8_t seal_alg[2])
1252 {
1253 	struct mbuf *m, *mlast, *tm, *cm, *pm;
1254 	size_t mlen, tlen, padlen, datalen;
1255 	uint8_t *p, dir;
1256 	size_t cklen;
1257 	uint8_t buf[8];
1258 	uint32_t seq;
1259 
1260 	/*
1261 	 * How many trailing pad bytes do we need?
1262 	 */
1263 	m = *mp;
1264 	mlen = m_length(m, &mlast);
1265 	tlen = kc->kc_tokenkey->ks_class->ec_msgblocklen;
1266 	padlen = tlen - (mlen % tlen);
1267 
1268 	/*
1269 	 * The data part of the token has eight bytes of random
1270 	 * confounder prepended and followed by up to eight bytes of
1271 	 * padding bytes each of which is set to the number of padding
1272 	 * bytes.
1273 	 */
1274 	datalen = mlen + 8 + padlen;
1275 	tlen = token_length(kc->kc_tokenkey);
1276 
1277 	p = krb5_make_token("\x02\x01", tlen, datalen + tlen, &tm);
1278 	p += 2;			/* TOK_ID */
1279 	*p++ = sgn_alg[0];	/* SGN_ALG */
1280 	*p++ = sgn_alg[1];
1281 	if (conf_req_flag) {
1282 		*p++ = seal_alg[0]; /* SEAL_ALG */
1283 		*p++ = seal_alg[1];
1284 	} else {
1285 		*p++ = 0xff;	/* SEAL_ALG = none */
1286 		*p++ = 0xff;
1287 	}
1288 
1289 	*p++ = 0xff;		/* filler */
1290 	*p++ = 0xff;
1291 
1292 	/*
1293 	 * Copy the padded message data.
1294 	 */
1295 	if (M_LEADINGSPACE(m) >= 8) {
1296 		m->m_data -= 8;
1297 		m->m_len += 8;
1298 	} else {
1299 		MGET(cm, M_WAITOK, MT_DATA);
1300 		cm->m_len = 8;
1301 		cm->m_next = m;
1302 		m = cm;
1303 	}
1304 	arc4rand(m->m_data, 8, 0);
1305 	if (M_TRAILINGSPACE(mlast) >= padlen) {
1306 		memset(mlast->m_data + mlast->m_len, padlen, padlen);
1307 		mlast->m_len += padlen;
1308 	} else {
1309 		MGET(pm, M_WAITOK, MT_DATA);
1310 		memset(pm->m_data, padlen, padlen);
1311 		pm->m_len = padlen;
1312 		mlast->m_next = pm;
1313 		mlast = pm;
1314 	}
1315 	tm->m_next = m;
1316 
1317 	/*
1318 	 * SGN_CKSUM:
1319 	 *
1320 	 * Calculate the keyed checksum of the token header plus the
1321 	 * padded message. Fiddle with tm->m_len so that we only
1322 	 * checksum the 8 bytes of head that we care about.
1323 	 */
1324 	cklen = kc->kc_checksumkey->ks_class->ec_checksumlen;
1325 	tlen = tm->m_len;
1326 	tm->m_len = p - (uint8_t *) tm->m_data;
1327 	MGET(cm, M_WAITOK, MT_DATA);
1328 	cm->m_len = cklen;
1329 	mlast->m_next = cm;
1330 	krb5_checksum(kc->kc_checksumkey, 13, tm, tm->m_len - 8,
1331 	    datalen + 8, cklen);
1332 	tm->m_len = tlen;
1333 	mlast->m_next = NULL;
1334 	bcopy(cm->m_data, p + 8, cklen);
1335 	m_free(cm);
1336 
1337 	/*
1338 	 * SND_SEQ:
1339 	 *
1340 	 * Take the four bytes of the sequence number least
1341 	 * significant first (most signficant first for ARCFOUR)
1342 	 * followed by four bytes of direction marker (zero for
1343 	 * initiator and 0xff for acceptor). Encrypt that data using
1344 	 * the SGN_CKSUM as IV.
1345 	 */
1346 	seq = atomic_fetchadd_32(&kc->kc_local_seqnumber, 1);
1347 	if (sgn_alg[0] == 0x11) {
1348 		p[0] = (seq >> 24);
1349 		p[1] = (seq >> 16);
1350 		p[2] = (seq >> 8);
1351 		p[3] = (seq >> 0);
1352 	} else {
1353 		p[0] = (seq >> 0);
1354 		p[1] = (seq >> 8);
1355 		p[2] = (seq >> 16);
1356 		p[3] = (seq >> 24);
1357 	}
1358 	if (is_initiator(kc)) {
1359 		dir = 0;
1360 	} else {
1361 		dir = 0xff;
1362 	}
1363 	p[4] = dir;
1364 	p[5] = dir;
1365 	p[6] = dir;
1366 	p[7] = dir;
1367 	krb5_encrypt(kc->kc_tokenkey, tm, p - (uint8_t *) tm->m_data,
1368 	    8, p + 8, 8);
1369 
1370 	if (conf_req_flag) {
1371 		/*
1372 		 * Encrypt the padded message with an IV of zero for
1373 		 * DES and DES3, or an IV of the sequence number in
1374 		 * big-endian format for ARCFOUR.
1375 		 */
1376 		if (seal_alg[0] == 0x10) {
1377 			buf[0] = (seq >> 24);
1378 			buf[1] = (seq >> 16);
1379 			buf[2] = (seq >> 8);
1380 			buf[3] = (seq >> 0);
1381 			krb5_encrypt(kc->kc_encryptkey, m, 0, datalen,
1382 			    buf, 4);
1383 		} else {
1384 			krb5_encrypt(kc->kc_encryptkey, m, 0, datalen,
1385 			    NULL, 0);
1386 		}
1387 	}
1388 
1389 	if (conf_state)
1390 		*conf_state = conf_req_flag;
1391 
1392 	*mp = tm;
1393 	return (GSS_S_COMPLETE);
1394 }
1395 
1396 static OM_uint32
1397 krb5_wrap_new(struct krb5_context *kc, int conf_req_flag,
1398     struct mbuf **mp, int *conf_state)
1399 {
1400 	struct krb5_key_state *Ke = kc->kc_send_seal_Ke;
1401 	struct krb5_key_state *Ki = kc->kc_send_seal_Ki;
1402 	struct krb5_key_state *Kc = kc->kc_send_seal_Kc;
1403 	const struct krb5_encryption_class *ec = Ke->ks_class;
1404 	struct mbuf *m, *mlast, *tm;
1405 	uint8_t *p;
1406 	int flags, EC;
1407 	size_t mlen, blen, mblen, cklen, ctlen;
1408 	uint32_t seq;
1409 	static char zpad[32];
1410 
1411 	m = *mp;
1412 	mlen = m_length(m, &mlast);
1413 
1414 	blen = ec->ec_blocklen;
1415 	mblen = ec->ec_msgblocklen;
1416 	cklen = ec->ec_checksumlen;
1417 
1418 	if (conf_req_flag) {
1419 		/*
1420 		 * For sealed messages, we need space for 16 bytes of
1421 		 * header, blen confounder, plaintext, padding, copy
1422 		 * of header and checksum.
1423 		 *
1424 		 * We pad to mblen (which may be different from
1425 		 * blen). If the encryption class is using CTS, mblen
1426 		 * will be one (i.e. no padding required).
1427 		 */
1428 		if (mblen > 1)
1429 			EC = mlen % mblen;
1430 		else
1431 			EC = 0;
1432 		ctlen = blen + mlen + EC + 16;
1433 
1434 		/*
1435 		 * Put initial header and confounder before the
1436 		 * message.
1437 		 */
1438 		M_PREPEND(m, 16 + blen, M_WAITOK);
1439 
1440 		/*
1441 		 * Append padding + copy of header and checksum. Try
1442 		 * to fit this into the end of the original message,
1443 		 * otherwise allocate a trailer.
1444 		 */
1445 		if (M_TRAILINGSPACE(mlast) >= EC + 16 + cklen) {
1446 			tm = NULL;
1447 			mlast->m_len += EC + 16 + cklen;
1448 		} else {
1449 			MGET(tm, M_WAITOK, MT_DATA);
1450 			tm->m_len = EC + 16 + cklen;
1451 			mlast->m_next = tm;
1452 		}
1453 	} else {
1454 		/*
1455 		 * For unsealed messages, we need 16 bytes of header
1456 		 * plus space for the plaintext and a checksum. EC is
1457 		 * set to the checksum size. We leave space in tm for
1458 		 * a copy of the header - this will be trimmed later.
1459 		 */
1460 		M_PREPEND(m, 16, M_WAITOK);
1461 
1462 		MGET(tm, M_WAITOK, MT_DATA);
1463 		tm->m_len = cklen + 16;
1464 		mlast->m_next = tm;
1465 		ctlen = 0;
1466 		EC = cklen;
1467 	}
1468 
1469 	p = m->m_data;
1470 
1471 	/* TOK_ID */
1472 	p[0] = 0x05;
1473 	p[1] = 0x04;
1474 
1475 	/* Flags */
1476 	flags = 0;
1477 	if (conf_req_flag)
1478 		flags = GSS_TOKEN_SEALED;
1479 	if (is_acceptor(kc))
1480 		flags |= GSS_TOKEN_SENT_BY_ACCEPTOR;
1481 	if (kc->kc_more_flags & ACCEPTOR_SUBKEY)
1482 		flags |= GSS_TOKEN_ACCEPTOR_SUBKEY;
1483 	p[2] = flags;
1484 
1485 	/* Filler */
1486 	p[3] = 0xff;
1487 
1488 	/* EC + RRC - set to zero initially */
1489 	p[4] = 0;
1490 	p[5] = 0;
1491 	p[6] = 0;
1492 	p[7] = 0;
1493 
1494 	/* SND_SEQ */
1495 	p[8] = 0;
1496 	p[9] = 0;
1497 	p[10] = 0;
1498 	p[11] = 0;
1499 	seq = atomic_fetchadd_32(&kc->kc_local_seqnumber, 1);
1500 	p[12] = (seq >> 24);
1501 	p[13] = (seq >> 16);
1502 	p[14] = (seq >> 8);
1503 	p[15] = (seq >> 0);
1504 
1505 	if (conf_req_flag) {
1506 		/*
1507 		 * Encrypt according to RFC 4121 section 4.2 and RFC
1508 		 * 3961 section 5.3. Note: we don't generate tokens
1509 		 * with RRC values other than zero. If we did, we
1510 		 * should zero RRC in the copied header.
1511 		 */
1512 		arc4rand(p + 16, blen, 0);
1513 		if (EC) {
1514 			m_copyback(m, 16 + blen + mlen, EC, zpad);
1515 		}
1516 		m_copyback(m, 16 + blen + mlen + EC, 16, p);
1517 
1518 		krb5_checksum(Ki, 0, m, 16, ctlen, cklen);
1519 		krb5_encrypt(Ke, m, 16, ctlen, NULL, 0);
1520 	} else {
1521 		/*
1522 		 * The plaintext message is followed by a checksum of
1523 		 * the plaintext plus a version of the header where EC
1524 		 * and RRC are set to zero. Also, the original EC must
1525 		 * be our checksum size.
1526 		 */
1527 		bcopy(p, tm->m_data, 16);
1528 		krb5_checksum(Kc, 0, m, 16, mlen + 16, cklen);
1529 		tm->m_data += 16;
1530 		tm->m_len -= 16;
1531 	}
1532 
1533 	/*
1534 	 * Finally set EC to its actual value
1535 	 */
1536 	p[4] = EC >> 8;
1537 	p[5] = EC;
1538 
1539 	*mp = m;
1540 	return (GSS_S_COMPLETE);
1541 }
1542 
1543 static OM_uint32
1544 krb5_wrap(gss_ctx_id_t ctx, OM_uint32 *minor_status,
1545     int conf_req_flag, gss_qop_t qop_req,
1546     struct mbuf **mp, int *conf_state)
1547 {
1548 	struct krb5_context *kc = (struct krb5_context *)ctx;
1549 
1550 	*minor_status = 0;
1551 	if (conf_state)
1552 		*conf_state = 0;
1553 
1554 	if (qop_req != GSS_C_QOP_DEFAULT)
1555 		return (GSS_S_BAD_QOP);
1556 
1557 	if (time_uptime > kc->kc_lifetime)
1558 		return (GSS_S_CONTEXT_EXPIRED);
1559 
1560 	switch (kc->kc_tokenkey->ks_class->ec_type) {
1561 	case ETYPE_DES_CBC_CRC:
1562 		return (krb5_wrap_old(kc, conf_req_flag,
1563 			mp, conf_state, sgn_alg_des_md5, seal_alg_des));
1564 
1565 	case ETYPE_ARCFOUR_HMAC_MD5:
1566 	case ETYPE_ARCFOUR_HMAC_MD5_56:
1567 		return (krb5_wrap_old(kc, conf_req_flag,
1568 			mp, conf_state, sgn_alg_hmac_md5, seal_alg_rc4));
1569 
1570 	case ETYPE_DES3_CBC_SHA1:
1571 		return (krb5_wrap_old(kc, conf_req_flag,
1572 			mp, conf_state, sgn_alg_des3_sha1, seal_alg_des3));
1573 
1574 	default:
1575 		return (krb5_wrap_new(kc, conf_req_flag, mp, conf_state));
1576 	}
1577 
1578 	return (GSS_S_FAILURE);
1579 }
1580 
1581 static void
1582 m_trim(struct mbuf *m, int len)
1583 {
1584 	struct mbuf *n;
1585 	int off;
1586 
1587 	n = m_getptr(m, len, &off);
1588 	if (n) {
1589 		n->m_len = off;
1590 		if (n->m_next) {
1591 			m_freem(n->m_next);
1592 			n->m_next = NULL;
1593 		}
1594 	}
1595 }
1596 
1597 static OM_uint32
1598 krb5_unwrap_old(struct krb5_context *kc, struct mbuf **mp, int *conf_state,
1599     uint8_t sgn_alg[2], uint8_t seal_alg[2])
1600 {
1601 	OM_uint32 res;
1602 	struct mbuf *m, *mlast, *hm, *cm;
1603 	uint8_t *p, dir;
1604 	size_t mlen, tlen, elen, datalen, padlen;
1605 	size_t cklen;
1606 	uint8_t buf[32];
1607 	uint32_t seq;
1608 	int i, conf;
1609 
1610 	m = *mp;
1611 	mlen = m_length(m, &mlast);
1612 
1613 	tlen = token_length(kc->kc_tokenkey);
1614 	cklen = kc->kc_tokenkey->ks_class->ec_checksumlen;
1615 
1616 	p = krb5_verify_token("\x02\x01", tlen, &m, &elen, TRUE);
1617 	*mp = m;
1618 	if (!p)
1619 		return (GSS_S_DEFECTIVE_TOKEN);
1620 	datalen = elen - tlen;
1621 
1622 	/*
1623 	 * Trim the framing header first to make life a little easier
1624 	 * later.
1625 	 */
1626 	m_adj(m, p - (uint8_t *) m->m_data);
1627 
1628 	/* TOK_ID */
1629 	p += 2;
1630 
1631 	/* SGN_ALG */
1632 	if (p[0] != sgn_alg[0] || p[1] != sgn_alg[1])
1633 		return (GSS_S_DEFECTIVE_TOKEN);
1634 	p += 2;
1635 
1636 	/* SEAL_ALG */
1637 	if (p[0] == seal_alg[0] && p[1] == seal_alg[1])
1638 		conf = 1;
1639 	else if (p[0] == 0xff && p[1] == 0xff)
1640 		conf = 0;
1641 	else
1642 		return (GSS_S_DEFECTIVE_TOKEN);
1643 	p += 2;
1644 
1645 	if (p[0] != 0xff || p[1] != 0xff)
1646 		return (GSS_S_DEFECTIVE_TOKEN);
1647 	p += 2;
1648 
1649 	/*
1650 	 * SND_SEQ:
1651 	 *
1652 	 * Take the four bytes of the sequence number least
1653 	 * significant first (most significant for ARCFOUR) followed
1654 	 * by four bytes of direction marker (zero for initiator and
1655 	 * 0xff for acceptor). Encrypt that data using the SGN_CKSUM
1656 	 * as IV.
1657 	 */
1658 	krb5_decrypt(kc->kc_tokenkey, m, 8, 8, p + 8, 8);
1659 	if (sgn_alg[0] == 0x11) {
1660 		seq = p[3] | (p[2] << 8) | (p[1] << 16) | (p[0] << 24);
1661 	} else {
1662 		seq = p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
1663 	}
1664 
1665 	if (is_initiator(kc)) {
1666 		dir = 0xff;
1667 	} else {
1668 		dir = 0;
1669 	}
1670 	if (p[4] != dir || p[5] != dir || p[6] != dir || p[7] != dir)
1671 		return (GSS_S_DEFECTIVE_TOKEN);
1672 
1673 	if (kc->kc_msg_order.km_flags &
1674 	    (GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG)) {
1675 		res = krb5_sequence_check(kc, seq);
1676 		if (GSS_ERROR(res))
1677 			return (res);
1678 	} else {
1679 		res = GSS_S_COMPLETE;
1680 	}
1681 
1682 	/*
1683 	 * If the token was encrypted, decode it in-place.
1684 	 */
1685 	if (conf) {
1686 		/*
1687 		 * Decrypt the padded message with an IV of zero for
1688 		 * DES and DES3 or an IV of the big-endian encoded
1689 		 * sequence number for ARCFOUR.
1690 		 */
1691 		if (seal_alg[0] == 0x10) {
1692 			krb5_decrypt(kc->kc_encryptkey, m, 16 + cklen,
1693 			    datalen, p, 4);
1694 		} else {
1695 			krb5_decrypt(kc->kc_encryptkey, m, 16 + cklen,
1696 			    datalen, NULL, 0);
1697 		}
1698 	}
1699 	if (conf_state)
1700 		*conf_state = conf;
1701 
1702 	/*
1703 	 * Check the trailing pad bytes.
1704 	 */
1705 	KASSERT(mlast->m_len > 0, ("Unexpected empty mbuf"));
1706 	padlen = mlast->m_data[mlast->m_len - 1];
1707 	m_copydata(m, tlen + datalen - padlen, padlen, buf);
1708 	for (i = 0; i < padlen; i++) {
1709 		if (buf[i] != padlen) {
1710 			return (GSS_S_DEFECTIVE_TOKEN);
1711 		}
1712 	}
1713 
1714 	/*
1715 	 * SGN_CKSUM:
1716 	 *
1717 	 * Calculate the keyed checksum of the token header plus the
1718 	 * padded message. We do a little mbuf surgery to trim out the
1719 	 * parts we don't want to checksum.
1720 	 */
1721 	hm = m;
1722 	*mp = m = m_split(m, 16 + cklen, M_WAITOK);
1723 	mlast = m_last(m);
1724 	hm->m_len = 8;
1725 	hm->m_next = m;
1726 	MGET(cm, M_WAITOK, MT_DATA);
1727 	cm->m_len = cklen;
1728 	mlast->m_next = cm;
1729 
1730 	krb5_checksum(kc->kc_checksumkey, 13, hm, 0, datalen + 8, cklen);
1731 	hm->m_next = NULL;
1732 	mlast->m_next = NULL;
1733 
1734 	if (bcmp(cm->m_data, hm->m_data + 16, cklen)) {
1735 		m_freem(hm);
1736 		m_free(cm);
1737 		return (GSS_S_BAD_SIG);
1738 	}
1739 	m_freem(hm);
1740 	m_free(cm);
1741 
1742 	/*
1743 	 * Trim off the confounder and padding.
1744 	 */
1745 	m_adj(m, 8);
1746 	if (mlast->m_len >= padlen) {
1747 		mlast->m_len -= padlen;
1748 	} else {
1749 		m_trim(m, datalen - 8 - padlen);
1750 	}
1751 
1752 	*mp = m;
1753 	return (res);
1754 }
1755 
1756 static OM_uint32
1757 krb5_unwrap_new(struct krb5_context *kc, struct mbuf **mp, int *conf_state)
1758 {
1759 	OM_uint32 res;
1760 	struct krb5_key_state *Ke = kc->kc_recv_seal_Ke;
1761 	struct krb5_key_state *Ki = kc->kc_recv_seal_Ki;
1762 	struct krb5_key_state *Kc = kc->kc_recv_seal_Kc;
1763 	const struct krb5_encryption_class *ec = Ke->ks_class;
1764 	struct mbuf *m, *mlast, *hm, *cm;
1765 	uint8_t *p, *pp;
1766 	int sealed, flags, EC, RRC;
1767 	size_t blen, cklen, ctlen, mlen, plen, tlen;
1768 	char buf[32], buf2[32];
1769 
1770 	m = *mp;
1771 	mlen = m_length(m, &mlast);
1772 
1773 	if (mlen <= 16)
1774 		return (GSS_S_DEFECTIVE_TOKEN);
1775 	if (m->m_len < 16) {
1776 		m = m_pullup(m, 16);
1777 		*mp = m;
1778 	}
1779 	p = m->m_data;
1780 
1781 	/* TOK_ID */
1782 	if (p[0] != 0x05)
1783 		return (GSS_S_DEFECTIVE_TOKEN);
1784 	if (p[1] != 0x04)
1785 		return (GSS_S_DEFECTIVE_TOKEN);
1786 
1787 	/* Flags */
1788 	sealed = p[2] & GSS_TOKEN_SEALED;
1789 	flags = sealed;
1790 	if (is_initiator(kc))
1791 		flags |= GSS_TOKEN_SENT_BY_ACCEPTOR;
1792 	if (kc->kc_more_flags & ACCEPTOR_SUBKEY)
1793 		flags |= GSS_TOKEN_ACCEPTOR_SUBKEY;
1794 	if (p[2] != flags)
1795 		return (GSS_S_DEFECTIVE_TOKEN);
1796 
1797 	/* Filler */
1798 	if (p[3] != 0xff)
1799 		return (GSS_S_DEFECTIVE_TOKEN);
1800 
1801 	/* EC + RRC */
1802 	EC = (p[4] << 8) + p[5];
1803 	RRC = (p[6] << 8) + p[7];
1804 
1805 	/* SND_SEQ */
1806 	if (kc->kc_msg_order.km_flags &
1807 		(GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG)) {
1808 		uint32_t seq;
1809 		if (p[8] || p[9] || p[10] || p[11]) {
1810 			res = GSS_S_UNSEQ_TOKEN;
1811 		} else {
1812 			seq = (p[12] << 24) | (p[13] << 16)
1813 				| (p[14] << 8) | p[15];
1814 			res = krb5_sequence_check(kc, seq);
1815 		}
1816 		if (GSS_ERROR(res))
1817 			return (res);
1818 	} else {
1819 		res = GSS_S_COMPLETE;
1820 	}
1821 
1822 	/*
1823 	 * Separate the header before dealing with RRC. We only need
1824 	 * to keep the header if the message isn't encrypted.
1825 	 */
1826 	if (sealed) {
1827 		hm = NULL;
1828 		m_adj(m, 16);
1829 	} else {
1830 		hm = m;
1831 		*mp = m = m_split(m, 16, M_WAITOK);
1832 		mlast = m_last(m);
1833 	}
1834 
1835 	/*
1836 	 * Undo the effects of RRC by rotating left.
1837 	 */
1838 	if (RRC > 0) {
1839 		struct mbuf *rm;
1840 		size_t rlen;
1841 
1842 		rlen = mlen - 16;
1843 		if (RRC <= sizeof(buf) && m->m_len >= rlen) {
1844 			/*
1845 			 * Simple case, just rearrange the bytes in m.
1846 			 */
1847 			bcopy(m->m_data, buf, RRC);
1848 			bcopy(m->m_data + RRC, m->m_data, rlen - RRC);
1849 			bcopy(buf, m->m_data + rlen - RRC, RRC);
1850 		} else {
1851 			/*
1852 			 * More complicated - rearrange the mbuf
1853 			 * chain.
1854 			 */
1855 			rm = m;
1856 			*mp = m = m_split(m, RRC, M_WAITOK);
1857 			m_cat(m, rm);
1858 			mlast = rm;
1859 		}
1860 	}
1861 
1862 	blen = ec->ec_blocklen;
1863 	cklen = ec->ec_checksumlen;
1864 	if (sealed) {
1865 		/*
1866 		 * Decrypt according to RFC 4121 section 4.2 and RFC
1867 		 * 3961 section 5.3. The message must be large enough
1868 		 * for a blocksize confounder, at least one block of
1869 		 * cyphertext and a checksum.
1870 		 */
1871 		if (mlen < 16 + 2*blen + cklen)
1872 			return (GSS_S_DEFECTIVE_TOKEN);
1873 
1874 		ctlen = mlen - 16 - cklen;
1875 		krb5_decrypt(Ke, m, 0, ctlen, NULL, 0);
1876 
1877 		/*
1878 		 * The size of the plaintext is ctlen minus blocklen
1879 		 * (for the confounder), 16 (for the copy of the token
1880 		 * header) and EC (for the filler). The actual
1881 		 * plaintext starts after the confounder.
1882 		 */
1883 		plen = ctlen - blen - 16 - EC;
1884 		pp = p + 16 + blen;
1885 
1886 		/*
1887 		 * Checksum the padded plaintext.
1888 		 */
1889 		m_copydata(m, ctlen, cklen, buf);
1890 		krb5_checksum(Ki, 0, m, 0, ctlen, cklen);
1891 		m_copydata(m, ctlen, cklen, buf2);
1892 
1893 		if (bcmp(buf, buf2, cklen))
1894 			return (GSS_S_BAD_SIG);
1895 
1896 		/*
1897 		 * Trim the message back to just plaintext.
1898 		 */
1899 		m_adj(m, blen);
1900 		tlen = 16 + EC + cklen;
1901 		if (mlast->m_len >= tlen) {
1902 			mlast->m_len -= tlen;
1903 		} else {
1904 			m_trim(m, plen);
1905 		}
1906 	} else {
1907 		/*
1908 		 * The plaintext message is followed by a checksum of
1909 		 * the plaintext plus a version of the header where EC
1910 		 * and RRC are set to zero. Also, the original EC must
1911 		 * be our checksum size.
1912 		 */
1913 		if (mlen < 16 + cklen || EC != cklen)
1914 			return (GSS_S_DEFECTIVE_TOKEN);
1915 
1916 		/*
1917 		 * The size of the plaintext is simply the message
1918 		 * size less header and checksum. The plaintext starts
1919 		 * right after the header (which we have saved in hm).
1920 		 */
1921 		plen = mlen - 16 - cklen;
1922 
1923 		/*
1924 		 * Insert a copy of the header (with EC and RRC set to
1925 		 * zero) between the plaintext message and the
1926 		 * checksum.
1927 		 */
1928 		p = hm->m_data;
1929 		p[4] = p[5] = p[6] = p[7] = 0;
1930 
1931 		cm = m_split(m, plen, M_WAITOK);
1932 		mlast = m_last(m);
1933 		m->m_next = hm;
1934 		hm->m_next = cm;
1935 
1936 		bcopy(cm->m_data, buf, cklen);
1937 		krb5_checksum(Kc, 0, m, 0, plen + 16, cklen);
1938 		if (bcmp(cm->m_data, buf, cklen))
1939 			return (GSS_S_BAD_SIG);
1940 
1941 		/*
1942 		 * The checksum matches, discard all buf the plaintext.
1943 		 */
1944 		mlast->m_next = NULL;
1945 		m_freem(hm);
1946 	}
1947 
1948 	if (conf_state)
1949 		*conf_state = (sealed != 0);
1950 
1951 	return (res);
1952 }
1953 
1954 static OM_uint32
1955 krb5_unwrap(gss_ctx_id_t ctx, OM_uint32 *minor_status,
1956     struct mbuf **mp, int *conf_state, gss_qop_t *qop_state)
1957 {
1958 	struct krb5_context *kc = (struct krb5_context *)ctx;
1959 	OM_uint32 maj_stat;
1960 
1961 	*minor_status = 0;
1962 	if (qop_state)
1963 		*qop_state = GSS_C_QOP_DEFAULT;
1964 	if (conf_state)
1965 		*conf_state = 0;
1966 
1967 	if (time_uptime > kc->kc_lifetime)
1968 		return (GSS_S_CONTEXT_EXPIRED);
1969 
1970 	switch (kc->kc_tokenkey->ks_class->ec_type) {
1971 	case ETYPE_DES_CBC_CRC:
1972 		maj_stat = krb5_unwrap_old(kc, mp, conf_state,
1973 			sgn_alg_des_md5, seal_alg_des);
1974 		break;
1975 
1976 	case ETYPE_ARCFOUR_HMAC_MD5:
1977 	case ETYPE_ARCFOUR_HMAC_MD5_56:
1978 		maj_stat = krb5_unwrap_old(kc, mp, conf_state,
1979 			sgn_alg_hmac_md5, seal_alg_rc4);
1980 		break;
1981 
1982 	case ETYPE_DES3_CBC_SHA1:
1983 		maj_stat = krb5_unwrap_old(kc, mp, conf_state,
1984 			sgn_alg_des3_sha1, seal_alg_des3);
1985 		break;
1986 
1987 	default:
1988 		maj_stat = krb5_unwrap_new(kc, mp, conf_state);
1989 		break;
1990 	}
1991 
1992 	if (GSS_ERROR(maj_stat)) {
1993 		m_freem(*mp);
1994 		*mp = NULL;
1995 	}
1996 
1997 	return (maj_stat);
1998 }
1999 
2000 static OM_uint32
2001 krb5_wrap_size_limit(gss_ctx_id_t ctx, OM_uint32 *minor_status,
2002     int conf_req_flag, gss_qop_t qop_req, OM_uint32 req_output_size,
2003     OM_uint32 *max_input_size)
2004 {
2005 	struct krb5_context *kc = (struct krb5_context *)ctx;
2006 	const struct krb5_encryption_class *ec;
2007 	OM_uint32 overhead;
2008 
2009 	*minor_status = 0;
2010 	*max_input_size = 0;
2011 
2012 	if (qop_req != GSS_C_QOP_DEFAULT)
2013 		return (GSS_S_BAD_QOP);
2014 
2015 	ec = kc->kc_tokenkey->ks_class;
2016 	switch (ec->ec_type) {
2017 	case ETYPE_DES_CBC_CRC:
2018 	case ETYPE_DES3_CBC_SHA1:
2019 	case ETYPE_ARCFOUR_HMAC_MD5:
2020 	case ETYPE_ARCFOUR_HMAC_MD5_56:
2021 		/*
2022 		 * up to 5 bytes for [APPLICATION 0] SEQUENCE
2023 		 * 2 + krb5 oid length
2024 		 * 8 bytes of header
2025 		 * 8 bytes of confounder
2026 		 * maximum of 8 bytes of padding
2027 		 * checksum
2028 		 */
2029 		overhead = 5 + 2 + krb5_mech_oid.length;
2030 		overhead += 8 + 8 + ec->ec_msgblocklen;
2031 		overhead += ec->ec_checksumlen;
2032 		break;
2033 
2034 	default:
2035 		if (conf_req_flag) {
2036 			/*
2037 			 * 16 byts of header
2038 			 * blocklen bytes of confounder
2039 			 * up to msgblocklen - 1 bytes of padding
2040 			 * 16 bytes for copy of header
2041 			 * checksum
2042 			 */
2043 			overhead = 16 + ec->ec_blocklen;
2044 			overhead += ec->ec_msgblocklen - 1;
2045 			overhead += 16;
2046 			overhead += ec->ec_checksumlen;
2047 		} else {
2048 			/*
2049 			 * 16 bytes of header plus checksum.
2050 			 */
2051 			overhead = 16 + ec->ec_checksumlen;
2052 		}
2053 	}
2054 
2055 	*max_input_size = req_output_size - overhead;
2056 
2057 	return (GSS_S_COMPLETE);
2058 }
2059 
2060 static kobj_method_t krb5_methods[] = {
2061 	KOBJMETHOD(kgss_init,		krb5_init),
2062 	KOBJMETHOD(kgss_import,		krb5_import),
2063 	KOBJMETHOD(kgss_delete,		krb5_delete),
2064 	KOBJMETHOD(kgss_mech_type,	krb5_mech_type),
2065 	KOBJMETHOD(kgss_get_mic,	krb5_get_mic),
2066 	KOBJMETHOD(kgss_verify_mic,	krb5_verify_mic),
2067 	KOBJMETHOD(kgss_wrap,		krb5_wrap),
2068 	KOBJMETHOD(kgss_unwrap,		krb5_unwrap),
2069 	KOBJMETHOD(kgss_wrap_size_limit, krb5_wrap_size_limit),
2070 	{ 0, 0 }
2071 };
2072 
2073 static struct kobj_class krb5_class = {
2074 	"kerberosv5",
2075 	krb5_methods,
2076 	sizeof(struct krb5_context)
2077 };
2078 
2079 /*
2080  * Kernel module glue
2081  */
2082 static int
2083 kgssapi_krb5_modevent(module_t mod, int type, void *data)
2084 {
2085 
2086 	switch (type) {
2087 	case MOD_LOAD:
2088 		kgss_install_mech(&krb5_mech_oid, "kerberosv5", &krb5_class);
2089 		break;
2090 
2091 	case MOD_UNLOAD:
2092 		kgss_uninstall_mech(&krb5_mech_oid);
2093 		break;
2094 	}
2095 
2096 
2097 	return (0);
2098 }
2099 static moduledata_t kgssapi_krb5_mod = {
2100 	"kgssapi_krb5",
2101 	kgssapi_krb5_modevent,
2102 	NULL,
2103 };
2104 DECLARE_MODULE(kgssapi_krb5, kgssapi_krb5_mod, SI_SUB_VFS, SI_ORDER_ANY);
2105 MODULE_DEPEND(kgssapi_krb5, kgssapi, 1, 1, 1);
2106 MODULE_DEPEND(kgssapi_krb5, crypto, 1, 1, 1);
2107 MODULE_DEPEND(kgssapi_krb5, rc4, 1, 1, 1);
2108 MODULE_VERSION(kgssapi_krb5, 1);
2109