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TOMOYO Linux Cross Reference
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 <crypto/skcipher.h>
 32 #include <linux/types.h>
 33 #include <linux/jiffies.h>
 34 #include <linux/sunrpc/gss_krb5.h>
 35 #include <linux/random.h>
 36 #include <linux/pagemap.h>
 37 
 38 #if IS_ENABLED(CONFIG_SUNRPC_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_SHIFT;
 83                 unsigned int offset = (buf->page_base + len - 1)
 84                                         & (PAGE_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_sync_skcipher_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         /*
205          * signalg and sealalg are stored as if they were converted from LE
206          * to host endian, even though they're opaque pairs of bytes according
207          * to the RFC.
208          */
209         *(__le16 *)(ptr + 2) = cpu_to_le16(kctx->gk5e->signalg);
210         *(__le16 *)(ptr + 4) = cpu_to_le16(kctx->gk5e->sealalg);
211         ptr[6] = 0xff;
212         ptr[7] = 0xff;
213 
214         gss_krb5_make_confounder(msg_start, conflen);
215 
216         if (kctx->gk5e->keyed_cksum)
217                 cksumkey = kctx->cksum;
218         else
219                 cksumkey = NULL;
220 
221         /* XXXJBF: UGH!: */
222         tmp_pages = buf->pages;
223         buf->pages = pages;
224         if (make_checksum(kctx, ptr, 8, buf, offset + headlen - conflen,
225                                         cksumkey, KG_USAGE_SEAL, &md5cksum))
226                 return GSS_S_FAILURE;
227         buf->pages = tmp_pages;
228 
229         memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);
230 
231         seq_send = atomic_fetch_inc(&kctx->seq_send);
232 
233         /* XXX would probably be more efficient to compute checksum
234          * and encrypt at the same time: */
235         if ((krb5_make_seq_num(kctx, kctx->seq, kctx->initiate ? 0 : 0xff,
236                                seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8)))
237                 return GSS_S_FAILURE;
238 
239         if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
240                 struct crypto_sync_skcipher *cipher;
241                 int err;
242                 cipher = crypto_alloc_sync_skcipher(kctx->gk5e->encrypt_name,
243                                                     0, 0);
244                 if (IS_ERR(cipher))
245                         return GSS_S_FAILURE;
246 
247                 krb5_rc4_setup_enc_key(kctx, cipher, seq_send);
248 
249                 err = gss_encrypt_xdr_buf(cipher, buf,
250                                           offset + headlen - conflen, pages);
251                 crypto_free_sync_skcipher(cipher);
252                 if (err)
253                         return GSS_S_FAILURE;
254         } else {
255                 if (gss_encrypt_xdr_buf(kctx->enc, buf,
256                                         offset + headlen - conflen, pages))
257                         return GSS_S_FAILURE;
258         }
259 
260         return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
261 }
262 
263 static u32
264 gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, struct xdr_buf *buf)
265 {
266         int                     signalg;
267         int                     sealalg;
268         char                    cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
269         struct xdr_netobj       md5cksum = {.len = sizeof(cksumdata),
270                                             .data = cksumdata};
271         s32                     now;
272         int                     direction;
273         s32                     seqnum;
274         unsigned char           *ptr;
275         int                     bodysize;
276         void                    *data_start, *orig_start;
277         int                     data_len;
278         int                     blocksize;
279         u32                     conflen = kctx->gk5e->conflen;
280         int                     crypt_offset;
281         u8                      *cksumkey;
282 
283         dprintk("RPC:       gss_unwrap_kerberos\n");
284 
285         ptr = (u8 *)buf->head[0].iov_base + offset;
286         if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
287                                         buf->len - offset))
288                 return GSS_S_DEFECTIVE_TOKEN;
289 
290         if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
291             (ptr[1] !=  (KG_TOK_WRAP_MSG & 0xff)))
292                 return GSS_S_DEFECTIVE_TOKEN;
293 
294         /* XXX sanity-check bodysize?? */
295 
296         /* get the sign and seal algorithms */
297 
298         signalg = ptr[2] + (ptr[3] << 8);
299         if (signalg != kctx->gk5e->signalg)
300                 return GSS_S_DEFECTIVE_TOKEN;
301 
302         sealalg = ptr[4] + (ptr[5] << 8);
303         if (sealalg != kctx->gk5e->sealalg)
304                 return GSS_S_DEFECTIVE_TOKEN;
305 
306         if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
307                 return GSS_S_DEFECTIVE_TOKEN;
308 
309         /*
310          * Data starts after token header and checksum.  ptr points
311          * to the beginning of the token header
312          */
313         crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) -
314                                         (unsigned char *)buf->head[0].iov_base;
315 
316         /*
317          * Need plaintext seqnum to derive encryption key for arcfour-hmac
318          */
319         if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
320                              ptr + 8, &direction, &seqnum))
321                 return GSS_S_BAD_SIG;
322 
323         if ((kctx->initiate && direction != 0xff) ||
324             (!kctx->initiate && direction != 0))
325                 return GSS_S_BAD_SIG;
326 
327         if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
328                 struct crypto_sync_skcipher *cipher;
329                 int err;
330 
331                 cipher = crypto_alloc_sync_skcipher(kctx->gk5e->encrypt_name,
332                                                     0, 0);
333                 if (IS_ERR(cipher))
334                         return GSS_S_FAILURE;
335 
336                 krb5_rc4_setup_enc_key(kctx, cipher, seqnum);
337 
338                 err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset);
339                 crypto_free_sync_skcipher(cipher);
340                 if (err)
341                         return GSS_S_DEFECTIVE_TOKEN;
342         } else {
343                 if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
344                         return GSS_S_DEFECTIVE_TOKEN;
345         }
346 
347         if (kctx->gk5e->keyed_cksum)
348                 cksumkey = kctx->cksum;
349         else
350                 cksumkey = NULL;
351 
352         if (make_checksum(kctx, ptr, 8, buf, crypt_offset,
353                                         cksumkey, KG_USAGE_SEAL, &md5cksum))
354                 return GSS_S_FAILURE;
355 
356         if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
357                                                 kctx->gk5e->cksumlength))
358                 return GSS_S_BAD_SIG;
359 
360         /* it got through unscathed.  Make sure the context is unexpired */
361 
362         now = get_seconds();
363 
364         if (now > kctx->endtime)
365                 return GSS_S_CONTEXT_EXPIRED;
366 
367         /* do sequencing checks */
368 
369         /* Copy the data back to the right position.  XXX: Would probably be
370          * better to copy and encrypt at the same time. */
371 
372         blocksize = crypto_sync_skcipher_blocksize(kctx->enc);
373         data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) +
374                                         conflen;
375         orig_start = buf->head[0].iov_base + offset;
376         data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
377         memmove(orig_start, data_start, data_len);
378         buf->head[0].iov_len -= (data_start - orig_start);
379         buf->len -= (data_start - orig_start);
380 
381         if (gss_krb5_remove_padding(buf, blocksize))
382                 return GSS_S_DEFECTIVE_TOKEN;
383 
384         return GSS_S_COMPLETE;
385 }
386 
387 /*
388  * We can shift data by up to LOCAL_BUF_LEN bytes in a pass.  If we need
389  * to do more than that, we shift repeatedly.  Kevin Coffman reports
390  * seeing 28 bytes as the value used by Microsoft clients and servers
391  * with AES, so this constant is chosen to allow handling 28 in one pass
392  * without using too much stack space.
393  *
394  * If that proves to a problem perhaps we could use a more clever
395  * algorithm.
396  */
397 #define LOCAL_BUF_LEN 32u
398 
399 static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift)
400 {
401         char head[LOCAL_BUF_LEN];
402         char tmp[LOCAL_BUF_LEN];
403         unsigned int this_len, i;
404 
405         BUG_ON(shift > LOCAL_BUF_LEN);
406 
407         read_bytes_from_xdr_buf(buf, 0, head, shift);
408         for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) {
409                 this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift));
410                 read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len);
411                 write_bytes_to_xdr_buf(buf, i, tmp, this_len);
412         }
413         write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift);
414 }
415 
416 static void _rotate_left(struct xdr_buf *buf, unsigned int shift)
417 {
418         int shifted = 0;
419         int this_shift;
420 
421         shift %= buf->len;
422         while (shifted < shift) {
423                 this_shift = min(shift - shifted, LOCAL_BUF_LEN);
424                 rotate_buf_a_little(buf, this_shift);
425                 shifted += this_shift;
426         }
427 }
428 
429 static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift)
430 {
431         struct xdr_buf subbuf;
432 
433         xdr_buf_subsegment(buf, &subbuf, base, buf->len - base);
434         _rotate_left(&subbuf, shift);
435 }
436 
437 static u32
438 gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
439                      struct xdr_buf *buf, struct page **pages)
440 {
441         u8              *ptr, *plainhdr;
442         s32             now;
443         u8              flags = 0x00;
444         __be16          *be16ptr;
445         __be64          *be64ptr;
446         u32             err;
447 
448         dprintk("RPC:       %s\n", __func__);
449 
450         if (kctx->gk5e->encrypt_v2 == NULL)
451                 return GSS_S_FAILURE;
452 
453         /* make room for gss token header */
454         if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN))
455                 return GSS_S_FAILURE;
456 
457         /* construct gss token header */
458         ptr = plainhdr = buf->head[0].iov_base + offset;
459         *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff);
460         *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff);
461 
462         if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
463                 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
464         if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0)
465                 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;
466         /* We always do confidentiality in wrap tokens */
467         flags |= KG2_TOKEN_FLAG_SEALED;
468 
469         *ptr++ = flags;
470         *ptr++ = 0xff;
471         be16ptr = (__be16 *)ptr;
472 
473         *be16ptr++ = 0;
474         /* "inner" token header always uses 0 for RRC */
475         *be16ptr++ = 0;
476 
477         be64ptr = (__be64 *)be16ptr;
478         *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64));
479 
480         err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, 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 

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