net/sunrpc/auth_gss/gss_krb5

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This source file includes following definitions.
gss_krb5_padding
gss_krb5_add_padding
gss_krb5_remove_padding
gss_krb5_make_confounder
gss_wrap_kerberos_v1
gss_unwrap_kerberos_v1
rotate_buf_a_little
_rotate_left
rotate_left
gss_wrap_kerberos_v2
gss_unwrap_kerberos_v2
gss_wrap_kerberos
gss_unwrap_kerberos
   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, int len,
 265                        struct xdr_buf *buf, unsigned int *slack,
 266                        unsigned int *align)
 267 {
 268         int                     signalg;
 269         int                     sealalg;
 270         char                    cksumdata[GSS_KRB5_MAX_CKSUM_LEN];
 271         struct xdr_netobj       md5cksum = {.len = sizeof(cksumdata),
 272                                             .data = cksumdata};
 273         s32                     now;
 274         int                     direction;
 275         s32                     seqnum;
 276         unsigned char           *ptr;
 277         int                     bodysize;
 278         void                    *data_start, *orig_start;
 279         int                     data_len;
 280         int                     blocksize;
 281         u32                     conflen = kctx->gk5e->conflen;
 282         int                     crypt_offset;
 283         u8                      *cksumkey;
 284         unsigned int            saved_len = buf->len;
 285 
 286         dprintk("RPC:       gss_unwrap_kerberos\n");
 287 
 288         ptr = (u8 *)buf->head[0].iov_base + offset;
 289         if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr,
 290                                         len - offset))
 291                 return GSS_S_DEFECTIVE_TOKEN;
 292 
 293         if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) ||
 294             (ptr[1] !=  (KG_TOK_WRAP_MSG & 0xff)))
 295                 return GSS_S_DEFECTIVE_TOKEN;
 296 
 297         /* XXX sanity-check bodysize?? */
 298 
 299         /* get the sign and seal algorithms */
 300 
 301         signalg = ptr[2] + (ptr[3] << 8);
 302         if (signalg != kctx->gk5e->signalg)
 303                 return GSS_S_DEFECTIVE_TOKEN;
 304 
 305         sealalg = ptr[4] + (ptr[5] << 8);
 306         if (sealalg != kctx->gk5e->sealalg)
 307                 return GSS_S_DEFECTIVE_TOKEN;
 308 
 309         if ((ptr[6] != 0xff) || (ptr[7] != 0xff))
 310                 return GSS_S_DEFECTIVE_TOKEN;
 311 
 312         /*
 313          * Data starts after token header and checksum.  ptr points
 314          * to the beginning of the token header
 315          */
 316         crypt_offset = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) -
 317                                         (unsigned char *)buf->head[0].iov_base;
 318 
 319         /*
 320          * Need plaintext seqnum to derive encryption key for arcfour-hmac
 321          */
 322         if (krb5_get_seq_num(kctx, ptr + GSS_KRB5_TOK_HDR_LEN,
 323                              ptr + 8, &direction, &seqnum))
 324                 return GSS_S_BAD_SIG;
 325 
 326         if ((kctx->initiate && direction != 0xff) ||
 327             (!kctx->initiate && direction != 0))
 328                 return GSS_S_BAD_SIG;
 329 
 330         buf->len = len;
 331         if (kctx->enctype == ENCTYPE_ARCFOUR_HMAC) {
 332                 struct crypto_sync_skcipher *cipher;
 333                 int err;
 334 
 335                 cipher = crypto_alloc_sync_skcipher(kctx->gk5e->encrypt_name,
 336                                                     0, 0);
 337                 if (IS_ERR(cipher))
 338                         return GSS_S_FAILURE;
 339 
 340                 krb5_rc4_setup_enc_key(kctx, cipher, seqnum);
 341 
 342                 err = gss_decrypt_xdr_buf(cipher, buf, crypt_offset);
 343                 crypto_free_sync_skcipher(cipher);
 344                 if (err)
 345                         return GSS_S_DEFECTIVE_TOKEN;
 346         } else {
 347                 if (gss_decrypt_xdr_buf(kctx->enc, buf, crypt_offset))
 348                         return GSS_S_DEFECTIVE_TOKEN;
 349         }
 350 
 351         if (kctx->gk5e->keyed_cksum)
 352                 cksumkey = kctx->cksum;
 353         else
 354                 cksumkey = NULL;
 355 
 356         if (make_checksum(kctx, ptr, 8, buf, crypt_offset,
 357                                         cksumkey, KG_USAGE_SEAL, &md5cksum))
 358                 return GSS_S_FAILURE;
 359 
 360         if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,
 361                                                 kctx->gk5e->cksumlength))
 362                 return GSS_S_BAD_SIG;
 363 
 364         /* it got through unscathed.  Make sure the context is unexpired */
 365 
 366         now = get_seconds();
 367 
 368         if (now > kctx->endtime)
 369                 return GSS_S_CONTEXT_EXPIRED;
 370 
 371         /* do sequencing checks */
 372 
 373         /* Copy the data back to the right position.  XXX: Would probably be
 374          * better to copy and encrypt at the same time. */
 375 
 376         blocksize = crypto_sync_skcipher_blocksize(kctx->enc);
 377         data_start = ptr + (GSS_KRB5_TOK_HDR_LEN + kctx->gk5e->cksumlength) +
 378                                         conflen;
 379         orig_start = buf->head[0].iov_base + offset;
 380         data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start;
 381         memmove(orig_start, data_start, data_len);
 382         buf->head[0].iov_len -= (data_start - orig_start);
 383         buf->len = len - (data_start - orig_start);
 384 
 385         if (gss_krb5_remove_padding(buf, blocksize))
 386                 return GSS_S_DEFECTIVE_TOKEN;
 387 
 388         /* slack must include room for krb5 padding */
 389         *slack = XDR_QUADLEN(saved_len - buf->len);
 390         /* The GSS blob always precedes the RPC message payload */
 391         *align = *slack;
 392         return GSS_S_COMPLETE;
 393 }
 394 
 395 /*
 396  * We can shift data by up to LOCAL_BUF_LEN bytes in a pass.  If we need
 397  * to do more than that, we shift repeatedly.  Kevin Coffman reports
 398  * seeing 28 bytes as the value used by Microsoft clients and servers
 399  * with AES, so this constant is chosen to allow handling 28 in one pass
 400  * without using too much stack space.
 401  *
 402  * If that proves to a problem perhaps we could use a more clever
 403  * algorithm.
 404  */
 405 #define LOCAL_BUF_LEN 32u
 406 
 407 static void rotate_buf_a_little(struct xdr_buf *buf, unsigned int shift)
 408 {
 409         char head[LOCAL_BUF_LEN];
 410         char tmp[LOCAL_BUF_LEN];
 411         unsigned int this_len, i;
 412 
 413         BUG_ON(shift > LOCAL_BUF_LEN);
 414 
 415         read_bytes_from_xdr_buf(buf, 0, head, shift);
 416         for (i = 0; i + shift < buf->len; i += LOCAL_BUF_LEN) {
 417                 this_len = min(LOCAL_BUF_LEN, buf->len - (i + shift));
 418                 read_bytes_from_xdr_buf(buf, i+shift, tmp, this_len);
 419                 write_bytes_to_xdr_buf(buf, i, tmp, this_len);
 420         }
 421         write_bytes_to_xdr_buf(buf, buf->len - shift, head, shift);
 422 }
 423 
 424 static void _rotate_left(struct xdr_buf *buf, unsigned int shift)
 425 {
 426         int shifted = 0;
 427         int this_shift;
 428 
 429         shift %= buf->len;
 430         while (shifted < shift) {
 431                 this_shift = min(shift - shifted, LOCAL_BUF_LEN);
 432                 rotate_buf_a_little(buf, this_shift);
 433                 shifted += this_shift;
 434         }
 435 }
 436 
 437 static void rotate_left(u32 base, struct xdr_buf *buf, unsigned int shift)
 438 {
 439         struct xdr_buf subbuf;
 440 
 441         xdr_buf_subsegment(buf, &subbuf, base, buf->len - base);
 442         _rotate_left(&subbuf, shift);
 443 }
 444 
 445 static u32
 446 gss_wrap_kerberos_v2(struct krb5_ctx *kctx, u32 offset,
 447                      struct xdr_buf *buf, struct page **pages)
 448 {
 449         u8              *ptr, *plainhdr;
 450         s32             now;
 451         u8              flags = 0x00;
 452         __be16          *be16ptr;
 453         __be64          *be64ptr;
 454         u32             err;
 455 
 456         dprintk("RPC:       %s\n", __func__);
 457 
 458         if (kctx->gk5e->encrypt_v2 == NULL)
 459                 return GSS_S_FAILURE;
 460 
 461         /* make room for gss token header */
 462         if (xdr_extend_head(buf, offset, GSS_KRB5_TOK_HDR_LEN))
 463                 return GSS_S_FAILURE;
 464 
 465         /* construct gss token header */
 466         ptr = plainhdr = buf->head[0].iov_base + offset;
 467         *ptr++ = (unsigned char) ((KG2_TOK_WRAP>>8) & 0xff);
 468         *ptr++ = (unsigned char) (KG2_TOK_WRAP & 0xff);
 469 
 470         if ((kctx->flags & KRB5_CTX_FLAG_INITIATOR) == 0)
 471                 flags |= KG2_TOKEN_FLAG_SENTBYACCEPTOR;
 472         if ((kctx->flags & KRB5_CTX_FLAG_ACCEPTOR_SUBKEY) != 0)
 473                 flags |= KG2_TOKEN_FLAG_ACCEPTORSUBKEY;
 474         /* We always do confidentiality in wrap tokens */
 475         flags |= KG2_TOKEN_FLAG_SEALED;
 476 
 477         *ptr++ = flags;
 478         *ptr++ = 0xff;
 479         be16ptr = (__be16 *)ptr;
 480 
 481         *be16ptr++ = 0;
 482         /* "inner" token header always uses 0 for RRC */
 483         *be16ptr++ = 0;
 484 
 485         be64ptr = (__be64 *)be16ptr;
 486         *be64ptr = cpu_to_be64(atomic64_fetch_inc(&kctx->seq_send64));
 487 
 488         err = (*kctx->gk5e->encrypt_v2)(kctx, offset, buf, pages);
 489         if (err)
 490                 return err;
 491 
 492         now = get_seconds();
 493         return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE;
 494 }
 495 
 496 static u32
 497 gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len,
 498                        struct xdr_buf *buf, unsigned int *slack,
 499                        unsigned int *align)
 500 {
 501         s32             now;
 502         u8              *ptr;
 503         u8              flags = 0x00;
 504         u16             ec, rrc;
 505         int             err;
 506         u32             headskip, tailskip;
 507         u8              decrypted_hdr[GSS_KRB5_TOK_HDR_LEN];
 508         unsigned int    movelen;
 509 
 510 
 511         dprintk("RPC:       %s\n", __func__);
 512 
 513         if (kctx->gk5e->decrypt_v2 == NULL)
 514                 return GSS_S_FAILURE;
 515 
 516         ptr = buf->head[0].iov_base + offset;
 517 
 518         if (be16_to_cpu(*((__be16 *)ptr)) != KG2_TOK_WRAP)
 519                 return GSS_S_DEFECTIVE_TOKEN;
 520 
 521         flags = ptr[2];
 522         if ((!kctx->initiate && (flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)) ||
 523             (kctx->initiate && !(flags & KG2_TOKEN_FLAG_SENTBYACCEPTOR)))
 524                 return GSS_S_BAD_SIG;
 525 
 526         if ((flags & KG2_TOKEN_FLAG_SEALED) == 0) {
 527                 dprintk("%s: token missing expected sealed flag\n", __func__);
 528                 return GSS_S_DEFECTIVE_TOKEN;
 529         }
 530 
 531         if (ptr[3] != 0xff)
 532                 return GSS_S_DEFECTIVE_TOKEN;
 533 
 534         ec = be16_to_cpup((__be16 *)(ptr + 4));
 535         rrc = be16_to_cpup((__be16 *)(ptr + 6));
 536 
 537         /*
 538          * NOTE: the sequence number at ptr + 8 is skipped, rpcsec_gss
 539          * doesn't want it checked; see page 6 of rfc 2203.
 540          */
 541 
 542         if (rrc != 0)
 543                 rotate_left(offset + 16, buf, rrc);
 544 
 545         err = (*kctx->gk5e->decrypt_v2)(kctx, offset, len, buf,
 546                                         &headskip, &tailskip);
 547         if (err)
 548                 return GSS_S_FAILURE;
 549 
 550         /*
 551          * Retrieve the decrypted gss token header and verify
 552          * it against the original
 553          */
 554         err = read_bytes_from_xdr_buf(buf,
 555                                 len - GSS_KRB5_TOK_HDR_LEN - tailskip,
 556                                 decrypted_hdr, GSS_KRB5_TOK_HDR_LEN);
 557         if (err) {
 558                 dprintk("%s: error %u getting decrypted_hdr\n", __func__, err);
 559                 return GSS_S_FAILURE;
 560         }
 561         if (memcmp(ptr, decrypted_hdr, 6)
 562                                 || memcmp(ptr + 8, decrypted_hdr + 8, 8)) {
 563                 dprintk("%s: token hdr, plaintext hdr mismatch!\n", __func__);
 564                 return GSS_S_FAILURE;
 565         }
 566 
 567         /* do sequencing checks */
 568 
 569         /* it got through unscathed.  Make sure the context is unexpired */
 570         now = get_seconds();
 571         if (now > kctx->endtime)
 572                 return GSS_S_CONTEXT_EXPIRED;
 573 
 574         /*
 575          * Move the head data back to the right position in xdr_buf.
 576          * We ignore any "ec" data since it might be in the head or
 577          * the tail, and we really don't need to deal with it.
 578          * Note that buf->head[0].iov_len may indicate the available
 579          * head buffer space rather than that actually occupied.
 580          */
 581         movelen = min_t(unsigned int, buf->head[0].iov_len, len);
 582         movelen -= offset + GSS_KRB5_TOK_HDR_LEN + headskip;
 583         BUG_ON(offset + GSS_KRB5_TOK_HDR_LEN + headskip + movelen >
 584                                                         buf->head[0].iov_len);
 585         memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
 586         buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
 587         buf->len = len - GSS_KRB5_TOK_HDR_LEN + headskip;
 588 
 589         /* Trim off the trailing "extra count" and checksum blob */
 590         xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
 591 
 592         *align = XDR_QUADLEN(GSS_KRB5_TOK_HDR_LEN + headskip);
 593         *slack = *align + XDR_QUADLEN(ec + GSS_KRB5_TOK_HDR_LEN + tailskip);
 594         return GSS_S_COMPLETE;
 595 }
 596 
 597 u32
 598 gss_wrap_kerberos(struct gss_ctx *gctx, int offset,
 599                   struct xdr_buf *buf, struct page **pages)
 600 {
 601         struct krb5_ctx *kctx = gctx->internal_ctx_id;
 602 
 603         switch (kctx->enctype) {
 604         default:
 605                 BUG();
 606         case ENCTYPE_DES_CBC_RAW:
 607         case ENCTYPE_DES3_CBC_RAW:
 608         case ENCTYPE_ARCFOUR_HMAC:
 609                 return gss_wrap_kerberos_v1(kctx, offset, buf, pages);
 610         case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 611         case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
 612                 return gss_wrap_kerberos_v2(kctx, offset, buf, pages);
 613         }
 614 }
 615 
 616 u32
 617 gss_unwrap_kerberos(struct gss_ctx *gctx, int offset,
 618                     int len, struct xdr_buf *buf)
 619 {
 620         struct krb5_ctx *kctx = gctx->internal_ctx_id;
 621 
 622         switch (kctx->enctype) {
 623         default:
 624                 BUG();
 625         case ENCTYPE_DES_CBC_RAW:
 626         case ENCTYPE_DES3_CBC_RAW:
 627         case ENCTYPE_ARCFOUR_HMAC:
 628                 return gss_unwrap_kerberos_v1(kctx, offset, len, buf,
 629                                               &gctx->slack, &gctx->align);
 630         case ENCTYPE_AES128_CTS_HMAC_SHA1_96:
 631         case ENCTYPE_AES256_CTS_HMAC_SHA1_96:
 632                 return gss_unwrap_kerberos_v2(kctx, offset, len, buf,
 633                                               &gctx->slack, &gctx->align);
 634         }
 635 }
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root/net/sunrpc/auth_gss/gss_krb5_wrap.c

DEFINITIONS
