1 /*
2  * COPYRIGHT (c) 2008
3  * The Regents of the University of Michigan
4  * ALL RIGHTS RESERVED
5  *
6  * Permission is granted to use, copy, create derivative works
7  * and redistribute this software and such derivative works
8  * for any purpose, so long as the name of The University of
9  * Michigan is not used in any advertising or publicity
10  * pertaining to the use of distribution of this software
11  * without specific, written prior authorization.  If the
12  * above copyright notice or any other identification of the
13  * University of Michigan is included in any copy of any
14  * portion of this software, then the disclaimer below must
15  * also be included.
16  *
17  * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
18  * FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
19  * PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
20  * MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
21  * WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
22  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
23  * REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
24  * FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
25  * CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
26  * OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
27  * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGES.
29  */
30 
31 #include <linux/types.h>
32 #include <linux/jiffies.h>
33 #include <linux/sunrpc/gss_krb5.h>
34 #include <linux/random.h>
35 #include <linux/pagemap.h>
36 #include <linux/crypto.h>
37 
38 #ifdef RPC_DEBUG
39 # define RPCDBG_FACILITY	RPCDBG_AUTH
40 #endif
41 
42 static inline int
43 gss_krb5_padding(int blocksize, int length)
44 {
45 	return blocksize - (length % blocksize);
46 }
47 
48 static inline void
49 gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize)
50 {
51 	int padding = gss_krb5_padding(blocksize, buf->len - offset);
52 	char *p;
53 	struct kvec *iov;
54 
55 	if (buf->page_len || buf->tail[0].iov_len)
56 		iov = &buf->tail[0];
57 	else
58 		iov = &buf->head[0];
59 	p = iov->iov_base + iov->iov_len;
60 	iov->iov_len += padding;
61 	buf->len += padding;
62 	memset(p, padding, padding);
63 }
64 
65 static inline int
66 gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize)
67 {
68 	u8 *ptr;
69 	u8 pad;
70 	size_t len = buf->len;
71 
72 	if (len <= buf->head[0].iov_len) {
73 		pad = *(u8 *)(buf->head[0].iov_base + len - 1);
74 		if (pad > buf->head[0].iov_len)
75 			return -EINVAL;
76 		buf->head[0].iov_len -= pad;
77 		goto out;
78 	} else
79 		len -= buf->head[0].iov_len;
80 	if (len <= buf->page_len) {
81 		unsigned int last = (buf->page_base + len - 1)
82 					>>PAGE_CACHE_SHIFT;
83 		unsigned int offset = (buf->page_base + len - 1)
84 					& (PAGE_CACHE_SIZE - 1);
85 		ptr = kmap_atomic(buf->pages[last]);
86 		pad = *(ptr + offset);
87 		kunmap_atomic(ptr);
88 		goto out;
89 	} else
90 		len -= buf->page_len;
91 	BUG_ON(len > buf->tail[0].iov_len);
92 	pad = *(u8 *)(buf->tail[0].iov_base + len - 1);
93 out:
94 	/* XXX: NOTE: we do not adjust the page lengths--they represent
95 	 * a range of data in the real filesystem page cache, and we need
96 	 * to know that range so the xdr code can properly place read data.
97 	 * However adjusting the head length, as we do above, is harmless.
98 	 * In the case of a request that fits into a single page, the server
99 	 * also uses length and head length together to determine the original
100 	 * start of the request to copy the request for deferal; so it's
101 	 * easier on the server if we adjust head and tail length in tandem.
102 	 * It's not really a problem that we don't fool with the page and
103 	 * tail lengths, though--at worst badly formed xdr might lead the
104 	 * server to attempt to parse the padding.
105 	 * XXX: Document all these weird requirements for gss mechanism
106 	 * wrap/unwrap functions. */
107 	if (pad > blocksize)
108 		return -EINVAL;
109 	if (buf->len > pad)
110 		buf->len -= pad;
111 	else
112 		return -EINVAL;
113 	return 0;
114 }
115 
116 void
117 gss_krb5_make_confounder(char *p, u32 conflen)
118 {
119 	static u64 i = 0;
120 	u64 *q = (u64 *)p;
121 
122 	/* rfc1964 claims this should be "random".  But all that's really
123 	 * necessary is that it be unique.  And not even that is necessary in
124 	 * our case since our "gssapi" implementation exists only to support
125 	 * rpcsec_gss, so we know that the only buffers we will ever encrypt
126 	 * already begin with a unique sequence number.  Just to hedge my bets
127 	 * I'll make a half-hearted attempt at something unique, but ensuring
128 	 * uniqueness would mean worrying about atomicity and rollover, and I
129 	 * don't care enough. */
130 
131 	/* initialize to random value */
132 	if (i == 0) {
133 		i = prandom_u32();
134 		i = (i << 32) | prandom_u32();
135 	}
136 
137 	switch (conflen) {
138 	case 16:
139 		*q++ = i++;
140 		/* fall through */
141 	case 8:
142 		*q++ = i++;
143 		break;
144 	default:
145 		BUG();
146 	}
147 }
148 
149 /* Assumptions: the head and tail of inbuf are ours to play with.
150  * The pages, however, may be real pages in the page cache and we replace
151  * them with scratch pages from **pages before writing to them. */
152 /* XXX: obviously the above should be documentation of wrap interface,
153  * and shouldn't be in this kerberos-specific file. */
154 
155 /* XXX factor out common code with seal/unseal. */
156 
157 static u32
158 gss_wrap_kerberos_v1(struct krb5_ctx *kctx, int offset,
159 		struct xdr_buf *buf, struct page **pages)
160 {
161 	char			cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
162 	struct xdr_netobj	md5cksum = {.len = sizeof(cksumdata),
163 					    .data = cksumdata};
164 	int			blocksize = 0, plainlen;
165 	unsigned char		*ptr, *msg_start;
166 	s32			now;
167 	int			headlen;
168 	struct page		**tmp_pages;
169 	u32			seq_send;
170 	u8			*cksumkey;
171 	u32			conflen = kctx->gk5e->conflen;
172 
173 	dprintk("RPC:       %s\n", __func__);
174 
175 	now = get_seconds();
176 
177 	blocksize = crypto_blkcipher_blocksize(kctx->enc);
178 	gss_krb5_add_padding(buf, offset, blocksize);
179 	BUG_ON((buf->len - offset) % blocksize);
180 	plainlen = conflen + buf->len - offset;
181 
182 	headlen = g_token_size(&kctx->mech_used,
183 		GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength + plainlen) -
184 		(buf->len - offset);
185 
186 	ptr = buf->head[0].iov_base + offset;
187 	/* shift data to make room for header. */
188 	xdr_extend_head(buf, offset, headlen);
189 
190 	/* XXX Would be cleverer to encrypt while copying. */
191 	BUG_ON((buf->len - offset - headlen) % blocksize);
192 
193 	g_make_token_header(&kctx->mech_used,
194 				GSS_KRB5_TOK_HDR_LEN +
195 				kctx->gk5e->cksumlength + plainlen, &ptr);
196 
197 
198 	/* ptr now at header described in rfc 1964, section 1.2.1: */
199 	ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff);
200 	ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff);
201 
202 	msg_start = ptr + GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength;
203 
204 	*(__be16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg);
205 	memset(ptr + 4, 0xff, 4);
206 	*(__be16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg);
207 
208 	gss_krb5_make_confounder(msg_start, conflen);
209 
210 	if (kctx->gk5e->keyed_cksum)
211 		cksumkey = kctx->cksum;
212 	else
213 		cksumkey = NULL;
214 
215 	/* XXXJBF: UGH!: */
216 	tmp_pages = buf->pages;
217 	buf->pages = pages;
218 	if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen,
219 					cksumkey, KG_USAGE_SEAL, &md5cksum))
220 		return GSS_S_FAILURE;
221 	buf->pages = tmp_pages;
222 
223 	memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
224 
225 	spin_lock(&krb5_seq_lock);
226 	seq_send = kctx->seq_send++;
227 	spin_unlock(&krb5_seq_lock);
228 
229 	/* XXX would probably be more efficient to compute checksum
230 	 * and encrypt at the same time: */
231 	if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff,
232 			       seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
233 		return GSS_S_FAILURE;
234 
235 	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
236 		struct crypto_blkcipher *cipher;
237 		int err;
238 		cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0,
239 						CRYPTO_ALG_ASYNC);
240 		if (IS_ERR(cipher))
241 			return GSS_S_FAILURE;
242 
243 		krb5_rc4_setup_enc_key(kctx, cipher, seq_send);
244 
245 		err = gss_encrypt_xdr_buf(cipher, buf,
246 					  offset + headlen - conflen, pages);
247 		crypto_free_blkcipher(cipher);
248 		if (err)
249 			return GSS_S_FAILURE;
250 	} else {
251 		if (gss_encrypt_xdr_buf(kctx->enc, buf,
252 					offset + headlen - conflen, pages))
253 			return GSS_S_FAILURE;
254 	}
255 
256 	return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
257 }
258 
259 static u32
260 gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
261 {
262 	int			signalg;
263 	int			sealalg;
264 	char			cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
265 	struct xdr_netobj	md5cksum = {.len = sizeof(cksumdata),
266 					    .data = cksumdata};
267 	s32			now;
268 	int			direction;
269 	s32			seqnum;
270 	unsigned char		*ptr;
271 	int			bodysize;
272 	void			*data_start, *orig_start;
273 	int			data_len;
274 	int			blocksize;
275 	u32			conflen = kctx->gk5e->conflen;
276 	int			crypt_offset;
277 	u8			*cksumkey;
278 
279 	dprintk("RPC:       gss_unwrap_kerberos\n");
280 
281 	ptr = (u8 *)buf->head[0].iov_base + offset;
282 	if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
283 					buf->len - offset))
284 		return GSS_S_DEFECTIVE_TOKEN;
285 
286 	if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
287 	    (ptr[1] !=  (KG_TOK_WRAP_MSG & 0xff)))
288 		return GSS_S_DEFECTIVE_TOKEN;
289 
290 	/* XXX sanity-check bodysize?? */
291 
292 	/* get the sign and seal algorithms */
293 
294 	signalg = ptr[2] + (ptr[3] << 8);
295 	if (signalg != kctx->gk5e->signalg)
296 		return GSS_S_DEFECTIVE_TOKEN;
297 
298 	sealalg = ptr[4] + (ptr[5] << 8);
299 	if (sealalg != kctx->gk5e->sealalg)
300 		return GSS_S_DEFECTIVE_TOKEN;
301 
302 	if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
303 		return GSS_S_DEFECTIVE_TOKEN;
304 
305 	/*
306 	 * Data starts after token header and checksum.  ptr points
307 	 * to the beginning of the token header
308 	 */
309 	crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) -
310 					(unsigned char *)buf->head[0].iov_base;
311 
312 	/*
313 	 * Need plaintext seqnum to derive encryption key for arcfour-hmac
314 	 */
315 	if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
316 			     ptr + 8, &direction, &seqnum))
317 		return GSS_S_BAD_SIG;
318 
319 	if ((kctx->initiate && direction != 0xff) ||
320 	    (!kctx->initiate && direction != 0))
321 		return GSS_S_BAD_SIG;
322 
323 	if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
324 		struct crypto_blkcipher *cipher;
325 		int err;
326 
327 		cipher = crypto_alloc_blkcipher(kctx->gk5e->encrypt_name, 0,
328 						CRYPTO_ALG_ASYNC);
329 		if (IS_ERR(cipher))
330 			return GSS_S_FAILURE;
331 
332 		krb5_rc4_setup_enc_key(kctx, cipher, seqnum);
333 
334 		err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset);
335 		crypto_free_blkcipher(cipher);
336 		if (err)
337 			return GSS_S_DEFECTIVE_TOKEN;
338 	} else {
339 		if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
340 			return GSS_S_DEFECTIVE_TOKEN;
341 	}
342 
343 	if (kctx->gk5e->keyed_cksum)
344 		cksumkey = kctx->cksum;
345 	else
346 		cksumkey = NULL;
347 
348 	if (make_checksum(kctx, ptr, 8, buf, crypt_offset,
349 					cksumkey, KG_USAGE_SEAL, &md5cksum))
350 		return GSS_S_FAILURE;
351 
352 	if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
353 						kctx->gk5e->cksumlength))
354 		return GSS_S_BAD_SIG;
355 
356 	/* it got through unscathed.  Make sure the context is unexpired */
357 
358 	now = get_seconds();
359 
360 	if (now > kctx->endtime)
361 		return GSS_S_CONTEXT_EXPIRED;
362 
363 	/* do sequencing checks */
364 
365 	/* Copy the data back to the right position.  XXX: Would probably be
366 	 * better to copy and encrypt at the same time. */
367 
368 	blocksize = crypto_blkcipher_blocksize(kctx->enc);
369 	data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) +
370 					conflen;
371 	orig_start = buf->head[0].iov_base + offset;
372 	data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
373 	memmove(orig_start, data_start, data_len);
374 	buf->head[0].iov_len -= (data_start - orig_start);
375 	buf->len -= (data_start - orig_start);
376 
377 	if (gss_krb5_remove_padding(buf, blocksize))
378 		return GSS_S_DEFECTIVE_TOKEN;
379 
380 	return GSS_S_COMPLETE;
381 }
382 
383 /*
384  * We can shift data by up to LOCAL_BUF_LEN bytes in a pass.  If we need
385  * to do more than that, we shift repeatedly.  Kevin Coffman reports
386  * seeing 28 bytes as the value used by Microsoft clients and servers
387  * with AES, so this constant is chosen to allow handling 28 in one pass
388  * without using too much stack space.
389  *
390  * If that proves to a problem perhaps we could use a more clever
391  * algorithm.
392  */
393 #define LOCAL_BUF_LEN 32u
394 
395 static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift)
396 {
397 	char head[LOCAL_BUF_LEN];
398 	char tmp[LOCAL_BUF_LEN];
399 	unsigned int this_len, i;
400 
401 	BUG_ON(shift > LOCAL_BUF_LEN);
402 
403 	read_bytes_from_xdr_buf(buf, 0, head, shift);
404 	for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) {
405 		this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift));
406 		read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len);
407 		write_bytes_to_xdr_buf(buf, i, tmp, this_len);
408 	}
409 	write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift);
410 }
411 
412 static void _rotate_left(struct xdr_buf *buf, unsigned int shift)
413 {
414 	int shifted = 0;
415 	int this_shift;
416 
417 	shift %= buf->len;
418 	while (shifted < shift) {
419 		this_shift = min(shift - shifted, LOCAL_BUF_LEN);
420 		rotate_buf_a_little(buf, this_shift);
421 		shifted += this_shift;
422 	}
423 }
424 
425 static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift)
426 {
427 	struct xdr_buf subbuf;
428 
429 	xdr_buf_subsegment(buf, &subbuf, base, buf->len - base);
430 	_rotate_left(&subbuf, shift);
431 }
432 
433 static u32
434 gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
435 		     struct xdr_buf *buf, struct page **pages)
436 {
437 	int		blocksize;
438 	u8		*ptr, *plainhdr;
439 	s32		now;
440 	u8		flags = 0x00;
441 	__be16		*be16ptr, ec = 0;
442 	__be64		*be64ptr;
443 	u32		err;
444 
445 	dprintk("RPC:       %s\n", __func__);
446 
447 	if (kctx->gk5e->encrypt_v2 == NULL)
448 		return GSS_S_FAILURE;
449 
450 	/* make room for gss token header */
451 	if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN))
452 		return GSS_S_FAILURE;
453 
454 	/* construct gss token header */
455 	ptr = plainhdr = buf->head[0].iov_base + offset;
456 	*ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff);
457 	*ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff);
458 
459 	if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
460 		flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
461 	if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0)
462 		flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;
463 	/* We always do confidentiality in wrap tokens */
464 	flags |= KG2_TOKEN_FLAG_SEALED;
465 
466 	*ptr++ = flags;
467 	*ptr++ = 0xff;
468 	be16ptr = (__be16 *)ptr;
469 
470 	blocksize = crypto_blkcipher_blocksize(kctx->acceptor_enc);
471 	*be16ptr++ = cpu_to_be16(ec);
472 	/* "inner" token header always uses 0 for RRC */
473 	*be16ptr++ = cpu_to_be16(0);
474 
475 	be64ptr = (__be64 *)be16ptr;
476 	spin_lock(&krb5_seq_lock);
477 	*be64ptr = cpu_to_be64(kctx->seq_send64++);
478 	spin_unlock(&krb5_seq_lock);
479 
480 	err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, ec, pages);
481 	if (err)
482 		return err;
483 
484 	now = get_seconds();
485 	return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
486 }
487 
488 static u32
489 gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
490 {
491 	s32		now;
492 	u8		*ptr;
493 	u8		flags = 0x00;
494 	u16		ec, rrc;
495 	int		err;
496 	u32		headskip, tailskip;
497 	u8		decrypted_hdr[GSS_KRB5_TOK_HDR_LEN];
498 	unsigned int	movelen;
499 
500 
501 	dprintk("RPC:       %s\n", __func__);
502 
503 	if (kctx->gk5e->decrypt_v2 == NULL)
504 		return GSS_S_FAILURE;
505 
506 	ptr = buf->head[0].iov_base + offset;
507 
508 	if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP)
509 		return GSS_S_DEFECTIVE_TOKEN;
510 
511 	flags = ptr[2];
512 	if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
513 	    (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
514 		return GSS_S_BAD_SIG;
515 
516 	if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) {
517 		dprintk("%s: token missing expected sealed flag\n", __func__);
518 		return GSS_S_DEFECTIVE_TOKEN;
519 	}
520 
521 	if (ptr[3] != 0xff)
522 		return GSS_S_DEFECTIVE_TOKEN;
523 
524 	ec = be16_to_cpup((__be16 *)(ptr + 4));
525 	rrc = be16_to_cpup((__be16 *)(ptr + 6));
526 
527 	/*
528 	 * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
529 	 * doesn't want it checked; see page 6 of rfc 2203.
530 	 */
531 
532 	if (rrc != 0)
533 		rotate_left(offset + 16, buf, rrc);
534 
535 	err = (*kctx->gk5e->decrypt_v2)(kctx, offset, buf,
536 					&headskip, &tailskip);
537 	if (err)
538 		return GSS_S_FAILURE;
539 
540 	/*
541 	 * Retrieve the decrypted gss token header and verify
542 	 * it against the original
543 	 */
544 	err = read_bytes_from_xdr_buf(buf,
545 				buf->len - GSS_KRB5_TOK_HDR_LEN - tailskip,
546 				decrypted_hdr, GSS_KRB5_TOK_HDR_LEN);
547 	if (err) {
548 		dprintk("%s: error %u getting decrypted_hdr\n", __func__, err);
549 		return GSS_S_FAILURE;
550 	}
551 	if (memcmp(ptr, decrypted_hdr, 6)
552 				|| memcmp(ptr + 8, decrypted_hdr + 8, 8)) {
553 		dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__);
554 		return GSS_S_FAILURE;
555 	}
556 
557 	/* do sequencing checks */
558 
559 	/* it got through unscathed.  Make sure the context is unexpired */
560 	now = get_seconds();
561 	if (now > kctx->endtime)
562 		return GSS_S_CONTEXT_EXPIRED;
563 
564 	/*
565 	 * Move the head data back to the right position in xdr_buf.
566 	 * We ignore any "ec" data since it might be in the head or
567 	 * the tail, and we really don't need to deal with it.
568 	 * Note that buf->head[0].iov_len may indicate the available
569 	 * head buffer space rather than that actually occupied.
570 	 */
571 	movelen = min_t(unsigned int, buf->head[0].iov_len, buf->len);
572 	movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
573 	BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
574 							buf->head[0].iov_len);
575 	memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
576 	buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
577 	buf->len -= GSS_KRB5_TOK_HDR_LEN + headskip;
578 
579 	/* Trim off the trailing "extra count" and checksum blob */
580 	xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
581 	return GSS_S_COMPLETE;
582 }
583 
584 u32
585 gss_wrap_kerberos(struct gss_ctx *gctx, int offset,
586 		  struct xdr_buf *buf, struct page **pages)
587 {
588 	struct krb5_ctx	*kctx = gctx->internal_ctx_id;
589 
590 	switch (kctx->enctype) {
591 	default:
592 		BUG();
593 	case ENCTYPE_DES_CBC_RAW:
594 	case ENCTYPE_DES3_CBC_RAW:
595 	case ENCTYPE_ARCFOUR_HMAC:
596 		return gss_wrap_kerberos_v1(kctx, offset, buf, pages);
597 	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
598 	case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
599 		return gss_wrap_kerberos_v2(kctx, offset, buf, pages);
600 	}
601 }
602 
603 u32
604 gss_unwrap_kerberos(struct gss_ctx *gctx, int offset, struct xdr_buf *buf)
605 {
606 	struct krb5_ctx	*kctx = gctx->internal_ctx_id;
607 
608 	switch (kctx->enctype) {
609 	default:
610 		BUG();
611 	case ENCTYPE_DES_CBC_RAW:
612 	case ENCTYPE_DES3_CBC_RAW:
613 	case ENCTYPE_ARCFOUR_HMAC:
614 		return gss_unwrap_kerberos_v1(kctx, offset, buf);
615 	case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
616 	case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
617 		return gss_unwrap_kerberos_v2(kctx, offset, buf);
618 	}
619 }
620 
621