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                 /* 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 = gss_seq_send_fetch_and_inc(kctx);
 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(gss_seq_send64_fetch_and_inc(kctx));
 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 }