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Linux/net/sunrpc/auth_gss/gss_krb5_wrap.c

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  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 

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