net/sunrpc/auth_gss/gss_krb5_wrap.c

   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                 fallthrough;
 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         time64_t                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 = ktime_get_real_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 (gss_encrypt_xdr_buf(kctx->enc, buf,
 240                                 offset + headlen - conflen, pages))
 241                 return GSS_S_FAILURE;
 242
 243         return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
 244 }
 245
 246 static u32
 247 gss_unwrap_kerberos_v1(struct krb5_ctx *kctx, int offset, int len,
 248                        struct xdr_buf *buf, unsigned int *slack,
 249                        unsigned int *align)
 250 {
 251         int                     signalg;
 252         int                     sealalg;
 253         char                    cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
 254         struct xdr_netobj       md5cksum = {.len = sizeof(cksumdata),
 255                                             .data = cksumdata};
 256         time64_t                now;
 257         int                     direction;
 258         s32                     seqnum;
 259         unsigned char           *ptr;
 260         int                     bodysize;
 261         void                    *data_start, *orig_start;
 262         int                     data_len;
 263         int                     blocksize;
 264         u32                     conflen = kctx->gk5e->conflen;
 265         int                     crypt_offset;
 266         u8                      *cksumkey;
 267         unsigned int            saved_len = buf->len;
 268
 269         dprintk("RPC:       gss_unwrap_kerberos\n");
 270
 271         ptr = (u8 *)buf->head[0].iov_base + offset;
 272         if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
 273                                         len - offset))
 274                 return GSS_S_DEFECTIVE_TOKEN;
 275
 276         if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
 277             (ptr[1] !=  (KG_TOK_WRAP_MSG & 0xff)))
 278                 return GSS_S_DEFECTIVE_TOKEN;
 279
 280         /* XXX sanity-check bodysize?? */
 281
 282         /* get the sign and seal algorithms */
 283
 284         signalg = ptr[2] + (ptr[3] << 8);
 285         if (signalg != kctx->gk5e->signalg)
 286                 return GSS_S_DEFECTIVE_TOKEN;
 287
 288         sealalg = ptr[4] + (ptr[5] << 8);
 289         if (sealalg != kctx->gk5e->sealalg)
 290                 return GSS_S_DEFECTIVE_TOKEN;
 291
 292         if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
 293                 return GSS_S_DEFECTIVE_TOKEN;
 294
 295         /*
 296          * Data starts after token header and checksum.  ptr points
 297          * to the beginning of the token header
 298          */
 299         crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) -
 300                                         (unsigned char *)buf->head[0].iov_base;
 301
 302         buf->len = len;
 303         if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
 304                 return GSS_S_DEFECTIVE_TOKEN;
 305
 306         if (kctx->gk5e->keyed_cksum)
 307                 cksumkey = kctx->cksum;
 308         else
 309                 cksumkey = NULL;
 310
 311         if (make_checksum(kctx, ptr, 8, buf, crypt_offset,
 312                                         cksumkey, KG_USAGE_SEAL, &md5cksum))
 313                 return GSS_S_FAILURE;
 314
 315         if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
 316                                                 kctx->gk5e->cksumlength))
 317                 return GSS_S_BAD_SIG;
 318
 319         /* it got through unscathed.  Make sure the context is unexpired */
 320
 321         now = ktime_get_real_seconds();
 322
 323         if (now > kctx->endtime)
 324                 return GSS_S_CONTEXT_EXPIRED;
 325
 326         /* do sequencing checks */
 327
 328         if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
 329                              ptr + 8, &direction, &seqnum))
 330                 return GSS_S_BAD_SIG;
 331
 332         if ((kctx->initiate && direction != 0xff) ||
 333             (!kctx->initiate && direction != 0))
 334                 return GSS_S_BAD_SIG;
 335
 336         /* Copy the data back to the right position.  XXX: Would probably be
 337          * better to copy and encrypt at the same time. */
 338
 339         blocksize = crypto_sync_skcipher_blocksize(kctx->enc);
 340         data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) +
 341                                         conflen;
 342         orig_start = buf->head[0].iov_base + offset;
 343         data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
 344         memmove(orig_start, data_start, data_len);
 345         buf->head[0].iov_len -= (data_start - orig_start);
 346         buf->len = len - (data_start - orig_start);
 347
 348         if (gss_krb5_remove_padding(buf, blocksize))
 349                 return GSS_S_DEFECTIVE_TOKEN;
 350
 351         /* slack must include room for krb5 padding */
 352         *slack = XDR_QUADLEN(saved_len - buf->len);
 353         /* The GSS blob always precedes the RPC message payload */
 354         *align = *slack;
 355         return GSS_S_COMPLETE;
 356 }
 357
 358 /*
 359  * We can shift data by up to LOCAL_BUF_LEN bytes in a pass.  If we need
 360  * to do more than that, we shift repeatedly.  Kevin Coffman reports
 361  * seeing 28 bytes as the value used by Microsoft clients and servers
 362  * with AES, so this constant is chosen to allow handling 28 in one pass
 363  * without using too much stack space.
 364  *
 365  * If that proves to a problem perhaps we could use a more clever
 366  * algorithm.
 367  */
 368 #define LOCAL_BUF_LEN 32u
 369
 370 static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift)
 371 {
 372         char head[LOCAL_BUF_LEN];
 373         char tmp[LOCAL_BUF_LEN];
 374         unsigned int this_len, i;
 375
 376         BUG_ON(shift > LOCAL_BUF_LEN);
 377
 378         read_bytes_from_xdr_buf(buf, 0, head, shift);
 379         for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) {
 380                 this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift));
 381                 read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len);
 382                 write_bytes_to_xdr_buf(buf, i, tmp, this_len);
 383         }
 384         write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift);
 385 }
 386
 387 static void _rotate_left(struct xdr_buf *buf, unsigned int shift)
 388 {
 389         int shifted = 0;
 390         int this_shift;
 391
 392         shift %= buf->len;
 393         while (shifted < shift) {
 394                 this_shift = min(shift - shifted, LOCAL_BUF_LEN);
 395                 rotate_buf_a_little(buf, this_shift);
 396                 shifted += this_shift;
 397         }
 398 }
 399
 400 static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift)
 401 {
 402         struct xdr_buf subbuf;
 403
 404         xdr_buf_subsegment(buf, &subbuf, base, buf->len - base);
 405         _rotate_left(&subbuf, shift);
 406 }
 407
 408 static u32
 409 gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
 410                      struct xdr_buf *buf, struct page **pages)
 411 {
 412         u8              *ptr, *plainhdr;
 413         time64_t        now;
 414         u8              flags = 0x00;
 415         __be16          *be16ptr;
 416         __be64          *be64ptr;
 417         u32             err;
 418
 419         dprintk("RPC:       %s\n", __func__);
 420
 421         if (kctx->gk5e->encrypt_v2 == NULL)
 422                 return GSS_S_FAILURE;
 423
 424         /* make room for gss token header */
 425         if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN))
 426                 return GSS_S_FAILURE;
 427
 428         /* construct gss token header */
 429         ptr = plainhdr = buf->head[0].iov_base + offset;
 430         *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff);
 431         *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff);
 432
 433         if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
 434                 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
 435         if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0)
 436                 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;
 437         /* We always do confidentiality in wrap tokens */
 438         flags |= KG2_TOKEN_FLAG_SEALED;
 439
 440         *ptr++ = flags;
 441         *ptr++ = 0xff;
 442         be16ptr = (__be16 *)ptr;
 443
 444         *be16ptr++ = 0;
 445         /* "inner" token header always uses 0 for RRC */
 446         *be16ptr++ = 0;
 447
 448         be64ptr = (__be64 *)be16ptr;
 449         *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64));
 450
 451         err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages);
 452         if (err)
 453                 return err;
 454
 455         now = ktime_get_real_seconds();
 456         return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
 457 }
 458
 459 static u32
 460 gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len,
 461                        struct xdr_buf *buf, unsigned int *slack,
 462                        unsigned int *align)
 463 {
 464         time64_t        now;
 465         u8              *ptr;
 466         u8              flags = 0x00;
 467         u16             ec, rrc;
 468         int             err;
 469         u32             headskip, tailskip;
 470         u8              decrypted_hdr[GSS_KRB5_TOK_HDR_LEN];
 471         unsigned int    movelen;
 472
 473
 474         dprintk("RPC:       %s\n", __func__);
 475
 476         if (kctx->gk5e->decrypt_v2 == NULL)
 477                 return GSS_S_FAILURE;
 478
 479         ptr = buf->head[0].iov_base + offset;
 480
 481         if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP)
 482                 return GSS_S_DEFECTIVE_TOKEN;
 483
 484         flags = ptr[2];
 485         if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
 486             (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
 487                 return GSS_S_BAD_SIG;
 488
 489         if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) {
 490                 dprintk("%s: token missing expected sealed flag\n", __func__);
 491                 return GSS_S_DEFECTIVE_TOKEN;
 492         }
 493
 494         if (ptr[3] != 0xff)
 495                 return GSS_S_DEFECTIVE_TOKEN;
 496
 497         ec = be16_to_cpup((__be16 *)(ptr + 4));
 498         rrc = be16_to_cpup((__be16 *)(ptr + 6));
 499
 500         /*
 501          * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
 502          * doesn't want it checked; see page 6 of rfc 2203.
 503          */
 504
 505         if (rrc != 0)
 506                 rotate_left(offset + 16, buf, rrc);
 507
 508         err = (*kctx->gk5e->decrypt_v2)(kctx, offset, len, buf,
 509                                         &headskip, &tailskip);
 510         if (err)
 511                 return GSS_S_FAILURE;
 512
 513         /*
 514          * Retrieve the decrypted gss token header and verify
 515          * it against the original
 516          */
 517         err = read_bytes_from_xdr_buf(buf,
 518                                 len - GSS_KRB5_TOK_HDR_LEN - tailskip,
 519                                 decrypted_hdr, GSS_KRB5_TOK_HDR_LEN);
 520         if (err) {
 521                 dprintk("%s: error %u getting decrypted_hdr\n", __func__, err);
 522                 return GSS_S_FAILURE;
 523         }
 524         if (memcmp(ptr, decrypted_hdr, 6)
 525                                 || memcmp(ptr + 8, decrypted_hdr + 8, 8)) {
 526                 dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__);
 527                 return GSS_S_FAILURE;
 528         }
 529
 530         /* do sequencing checks */
 531
 532         /* it got through unscathed.  Make sure the context is unexpired */
 533         now = ktime_get_real_seconds();
 534         if (now > kctx->endtime)
 535                 return GSS_S_CONTEXT_EXPIRED;
 536
 537         /*
 538          * Move the head data back to the right position in xdr_buf.
 539          * We ignore any "ec" data since it might be in the head or
 540          * the tail, and we really don't need to deal with it.
 541          * Note that buf->head[0].iov_len may indicate the available
 542          * head buffer space rather than that actually occupied.
 543          */
 544         movelen = min_t(unsigned int, buf->head[0].iov_len, len);
 545         movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
 546         BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
 547                                                         buf->head[0].iov_len);
 548         memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
 549         buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
 550         buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);
 551
 552         /* Trim off the trailing "extra count" and checksum blob */
 553         xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
 554
 555         *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip);
 556         *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
 557         return GSS_S_COMPLETE;
 558 }
 559
 560 u32
 561 gss_wrap_kerberos(struct gss_ctx *gctx, int offset,
 562                   struct xdr_buf *buf, struct page **pages)
 563 {
 564         struct krb5_ctx *kctx = gctx->internal_ctx_id;
 565
 566         switch (kctx->enctype) {
 567         default:
 568                 BUG();
 569         case ENCTYPE_DES_CBC_RAW:
 570         case ENCTYPE_DES3_CBC_RAW:
 571                 return gss_wrap_kerberos_v1(kctx, offset, buf, pages);
 572         case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 573         case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
 574                 return gss_wrap_kerberos_v2(kctx, offset, buf, pages);
 575         }
 576 }
 577
 578 u32
 579 gss_unwrap_kerberos(struct gss_ctx *gctx, int offset,
 580                     int len, struct xdr_buf *buf)
 581 {
 582         struct krb5_ctx *kctx = gctx->internal_ctx_id;
 583
 584         switch (kctx->enctype) {
 585         default:
 586                 BUG();
 587         case ENCTYPE_DES_CBC_RAW:
 588         case ENCTYPE_DES3_CBC_RAW:
 589                 return gss_unwrap_kerberos_v1(kctx, offset, len, buf,
 590                                               &gctx->slack, &gctx->align);
 591         case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 592         case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
 593                 return gss_unwrap_kerberos_v2(kctx, offset, len, buf,
 594                                               &gctx->slack, &gctx->align);
 595         }
 596 }