net/sunrpc/auth_gss/gss_krb5_crypto.c

   1 /*
   2  *  linux/net/sunrpc/gss_krb5_crypto.c
   3  *
   4  *  Copyright (c) 2000-2008 The Regents of the University of Michigan.
   5  *  All rights reserved.
   6  *
   7  *  Andy Adamson   <andros@umich.edu>
   8  *  Bruce Fields   <bfields@umich.edu>
   9  */
  10
  11 /*
  12  * Copyright (C) 1998 by the FundsXpress, INC.
  13  *
  14  * All rights reserved.
  15  *
  16  * Export of this software from the United States of America may require
  17  * a specific license from the United States Government.  It is the
  18  * responsibility of any person or organization contemplating export to
  19  * obtain such a license before exporting.
  20  *
  21  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
  22  * distribute this software and its documentation for any purpose and
  23  * without fee is hereby granted, provided that the above copyright
  24  * notice appear in all copies and that both that copyright notice and
  25  * this permission notice appear in supporting documentation, and that
  26  * the name of FundsXpress. not be used in advertising or publicity pertaining
  27  * to distribution of the software without specific, written prior
  28  * permission.  FundsXpress makes no representations about the suitability of
  29  * this software for any purpose.  It is provided "as is" without express
  30  * or implied warranty.
  31  *
  32  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  33  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  34  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  35  */
  36
  37 #include <linux/err.h>
  38 #include <linux/types.h>
  39 #include <linux/mm.h>
  40 #include <linux/scatterlist.h>
  41 #include <linux/crypto.h>
  42 #include <linux/highmem.h>
  43 #include <linux/pagemap.h>
  44 #include <linux/random.h>
  45 #include <linux/sunrpc/gss_krb5.h>
  46 #include <linux/sunrpc/xdr.h>
  47
  48 #ifdef RPC_DEBUG
  49 # define RPCDBG_FACILITY        RPCDBG_AUTH
  50 #endif
  51
  52 u32
  53 krb5_encrypt(
  54         struct crypto_blkcipher *tfm,
  55         void * iv,
  56         void * in,
  57         void * out,
  58         int length)
  59 {
  60         u32 ret = -EINVAL;
  61         struct scatterlist sg[1];
  62         u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
  63         struct blkcipher_desc desc = { .tfm = tfm, .info = local_iv };
  64
  65         if (length % crypto_blkcipher_blocksize(tfm) != 0)
  66                 goto out;
  67
  68         if (crypto_blkcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
  69                 dprintk("RPC:       gss_k5encrypt: tfm iv size too large %d\n",
  70                         crypto_blkcipher_ivsize(tfm));
  71                 goto out;
  72         }
  73
  74         if (iv)
  75                 memcpy(local_iv, iv, crypto_blkcipher_ivsize(tfm));
  76
  77         memcpy(out, in, length);
  78         sg_init_one(sg, out, length);
  79
  80         ret = crypto_blkcipher_encrypt_iv(&desc, sg, sg, length);
  81 out:
  82         dprintk("RPC:       krb5_encrypt returns %d\n", ret);
  83         return ret;
  84 }
  85
  86 u32
  87 krb5_decrypt(
  88      struct crypto_blkcipher *tfm,
  89      void * iv,
  90      void * in,
  91      void * out,
  92      int length)
  93 {
  94         u32 ret = -EINVAL;
  95         struct scatterlist sg[1];
  96         u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
  97         struct blkcipher_desc desc = { .tfm = tfm, .info = local_iv };
  98
  99         if (length % crypto_blkcipher_blocksize(tfm) != 0)
 100                 goto out;
 101
 102         if (crypto_blkcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
 103                 dprintk("RPC:       gss_k5decrypt: tfm iv size too large %d\n",
 104                         crypto_blkcipher_ivsize(tfm));
 105                 goto out;
 106         }
 107         if (iv)
 108                 memcpy(local_iv,iv, crypto_blkcipher_ivsize(tfm));
 109
 110         memcpy(out, in, length);
 111         sg_init_one(sg, out, length);
 112
 113         ret = crypto_blkcipher_decrypt_iv(&desc, sg, sg, length);
 114 out:
 115         dprintk("RPC:       gss_k5decrypt returns %d\n",ret);
 116         return ret;
 117 }
 118
 119 static int
 120 checksummer(struct scatterlist *sg, void *data)
 121 {
 122         struct hash_desc *desc = data;
 123
 124         return crypto_hash_update(desc, sg, sg->length);
 125 }
 126
 127 static int
 128 arcfour_hmac_md5_usage_to_salt(unsigned int usage, u8 salt[4])
 129 {
 130         unsigned int ms_usage;
 131
 132         switch (usage) {
 133         case KG_USAGE_SIGN:
 134                 ms_usage = 15;
 135                 break;
 136         case KG_USAGE_SEAL:
 137                 ms_usage = 13;
 138                 break;
 139         default:
 140                 return -EINVAL;
 141         }
 142         salt[0] = (ms_usage >> 0) & 0xff;
 143         salt[1] = (ms_usage >> 8) & 0xff;
 144         salt[2] = (ms_usage >> 16) & 0xff;
 145         salt[3] = (ms_usage >> 24) & 0xff;
 146
 147         return 0;
 148 }
 149
 150 static u32
 151 make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
 152                        struct xdr_buf *body, int body_offset, u8 *cksumkey,
 153                        unsigned int usage, struct xdr_netobj *cksumout)
 154 {
 155         struct hash_desc                desc;
 156         struct scatterlist              sg[1];
 157         int err;
 158         u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
 159         u8 rc4salt[4];
 160         struct crypto_hash *md5;
 161         struct crypto_hash *hmac_md5;
 162
 163         if (cksumkey == NULL)
 164                 return GSS_S_FAILURE;
 165
 166         if (cksumout->len < kctx->gk5e->cksumlength) {
 167                 dprintk("%s: checksum buffer length, %u, too small for %s\n",
 168                         __func__, cksumout->len, kctx->gk5e->name);
 169                 return GSS_S_FAILURE;
 170         }
 171
 172         if (arcfour_hmac_md5_usage_to_salt(usage, rc4salt)) {
 173                 dprintk("%s: invalid usage value %u\n", __func__, usage);
 174                 return GSS_S_FAILURE;
 175         }
 176
 177         md5 = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
 178         if (IS_ERR(md5))
 179                 return GSS_S_FAILURE;
 180
 181         hmac_md5 = crypto_alloc_hash(kctx->gk5e->cksum_name, 0,
 182                                      CRYPTO_ALG_ASYNC);
 183         if (IS_ERR(hmac_md5)) {
 184                 crypto_free_hash(md5);
 185                 return GSS_S_FAILURE;
 186         }
 187
 188         desc.tfm = md5;
 189         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 190
 191         err = crypto_hash_init(&desc);
 192         if (err)
 193                 goto out;
 194         sg_init_one(sg, rc4salt, 4);
 195         err = crypto_hash_update(&desc, sg, 4);
 196         if (err)
 197                 goto out;
 198
 199         sg_init_one(sg, header, hdrlen);
 200         err = crypto_hash_update(&desc, sg, hdrlen);
 201         if (err)
 202                 goto out;
 203         err = xdr_process_buf(body, body_offset, body->len - body_offset,
 204                               checksummer, &desc);
 205         if (err)
 206                 goto out;
 207         err = crypto_hash_final(&desc, checksumdata);
 208         if (err)
 209                 goto out;
 210
 211         desc.tfm = hmac_md5;
 212         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 213
 214         err = crypto_hash_init(&desc);
 215         if (err)
 216                 goto out;
 217         err = crypto_hash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength);
 218         if (err)
 219                 goto out;
 220
 221         sg_init_one(sg, checksumdata, crypto_hash_digestsize(md5));
 222         err = crypto_hash_digest(&desc, sg, crypto_hash_digestsize(md5),
 223                                  checksumdata);
 224         if (err)
 225                 goto out;
 226
 227         memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
 228         cksumout->len = kctx->gk5e->cksumlength;
 229 out:
 230         crypto_free_hash(md5);
 231         crypto_free_hash(hmac_md5);
 232         return err ? GSS_S_FAILURE : 0;
 233 }
 234
 235 /*
 236  * checksum the plaintext data and hdrlen bytes of the token header
 237  * The checksum is performed over the first 8 bytes of the
 238  * gss token header and then over the data body
 239  */
 240 u32
 241 make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
 242               struct xdr_buf *body, int body_offset, u8 *cksumkey,
 243               unsigned int usage, struct xdr_netobj *cksumout)
 244 {
 245         struct hash_desc                desc;
 246         struct scatterlist              sg[1];
 247         int err;
 248         u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
 249         unsigned int checksumlen;
 250
 251         if (kctx->gk5e->ctype == CKSUMTYPE_HMAC_MD5_ARCFOUR)
 252                 return make_checksum_hmac_md5(kctx, header, hdrlen,
 253                                               body, body_offset,
 254                                               cksumkey, usage, cksumout);
 255
 256         if (cksumout->len < kctx->gk5e->cksumlength) {
 257                 dprintk("%s: checksum buffer length, %u, too small for %s\n",
 258                         __func__, cksumout->len, kctx->gk5e->name);
 259                 return GSS_S_FAILURE;
 260         }
 261
 262         desc.tfm = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
 263         if (IS_ERR(desc.tfm))
 264                 return GSS_S_FAILURE;
 265         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 266
 267         checksumlen = crypto_hash_digestsize(desc.tfm);
 268
 269         if (cksumkey != NULL) {
 270                 err = crypto_hash_setkey(desc.tfm, cksumkey,
 271                                          kctx->gk5e->keylength);
 272                 if (err)
 273                         goto out;
 274         }
 275
 276         err = crypto_hash_init(&desc);
 277         if (err)
 278                 goto out;
 279         sg_init_one(sg, header, hdrlen);
 280         err = crypto_hash_update(&desc, sg, hdrlen);
 281         if (err)
 282                 goto out;
 283         err = xdr_process_buf(body, body_offset, body->len - body_offset,
 284                               checksummer, &desc);
 285         if (err)
 286                 goto out;
 287         err = crypto_hash_final(&desc, checksumdata);
 288         if (err)
 289                 goto out;
 290
 291         switch (kctx->gk5e->ctype) {
 292         case CKSUMTYPE_RSA_MD5:
 293                 err = kctx->gk5e->encrypt(kctx->seq, NULL, checksumdata,
 294                                           checksumdata, checksumlen);
 295                 if (err)
 296                         goto out;
 297                 memcpy(cksumout->data,
 298                        checksumdata + checksumlen - kctx->gk5e->cksumlength,
 299                        kctx->gk5e->cksumlength);
 300                 break;
 301         case CKSUMTYPE_HMAC_SHA1_DES3:
 302                 memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
 303                 break;
 304         default:
 305                 BUG();
 306                 break;
 307         }
 308         cksumout->len = kctx->gk5e->cksumlength;
 309 out:
 310         crypto_free_hash(desc.tfm);
 311         return err ? GSS_S_FAILURE : 0;
 312 }
 313
 314 /*
 315  * checksum the plaintext data and hdrlen bytes of the token header
 316  * Per rfc4121, sec. 4.2.4, the checksum is performed over the data
 317  * body then over the first 16 octets of the MIC token
 318  * Inclusion of the header data in the calculation of the
 319  * checksum is optional.
 320  */
 321 u32
 322 make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
 323                  struct xdr_buf *body, int body_offset, u8 *cksumkey,
 324                  unsigned int usage, struct xdr_netobj *cksumout)
 325 {
 326         struct hash_desc desc;
 327         struct scatterlist sg[1];
 328         int err;
 329         u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];
 330         unsigned int checksumlen;
 331
 332         if (kctx->gk5e->keyed_cksum == 0) {
 333                 dprintk("%s: expected keyed hash for %s\n",
 334                         __func__, kctx->gk5e->name);
 335                 return GSS_S_FAILURE;
 336         }
 337         if (cksumkey == NULL) {
 338                 dprintk("%s: no key supplied for %s\n",
 339                         __func__, kctx->gk5e->name);
 340                 return GSS_S_FAILURE;
 341         }
 342
 343         desc.tfm = crypto_alloc_hash(kctx->gk5e->cksum_name, 0,
 344                                                         CRYPTO_ALG_ASYNC);
 345         if (IS_ERR(desc.tfm))
 346                 return GSS_S_FAILURE;
 347         checksumlen = crypto_hash_digestsize(desc.tfm);
 348         desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 349
 350         err = crypto_hash_setkey(desc.tfm, cksumkey, kctx->gk5e->keylength);
 351         if (err)
 352                 goto out;
 353
 354         err = crypto_hash_init(&desc);
 355         if (err)
 356                 goto out;
 357         err = xdr_process_buf(body, body_offset, body->len - body_offset,
 358                               checksummer, &desc);
 359         if (err)
 360                 goto out;
 361         if (header != NULL) {
 362                 sg_init_one(sg, header, hdrlen);
 363                 err = crypto_hash_update(&desc, sg, hdrlen);
 364                 if (err)
 365                         goto out;
 366         }
 367         err = crypto_hash_final(&desc, checksumdata);
 368         if (err)
 369                 goto out;
 370
 371         cksumout->len = kctx->gk5e->cksumlength;
 372
 373         switch (kctx->gk5e->ctype) {
 374         case CKSUMTYPE_HMAC_SHA1_96_AES128:
 375         case CKSUMTYPE_HMAC_SHA1_96_AES256:
 376                 /* note that this truncates the hash */
 377                 memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
 378                 break;
 379         default:
 380                 BUG();
 381                 break;
 382         }
 383 out:
 384         crypto_free_hash(desc.tfm);
 385         return err ? GSS_S_FAILURE : 0;
 386 }
 387
 388 struct encryptor_desc {
 389         u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
 390         struct blkcipher_desc desc;
 391         int pos;
 392         struct xdr_buf *outbuf;
 393         struct page **pages;
 394         struct scatterlist infrags[4];
 395         struct scatterlist outfrags[4];
 396         int fragno;
 397         int fraglen;
 398 };
 399
 400 static int
 401 encryptor(struct scatterlist *sg, void *data)
 402 {
 403         struct encryptor_desc *desc = data;
 404         struct xdr_buf *outbuf = desc->outbuf;
 405         struct page *in_page;
 406         int thislen = desc->fraglen + sg->length;
 407         int fraglen, ret;
 408         int page_pos;
 409
 410         /* Worst case is 4 fragments: head, end of page 1, start
 411          * of page 2, tail.  Anything more is a bug. */
 412         BUG_ON(desc->fragno > 3);
 413
 414         page_pos = desc->pos - outbuf->head[0].iov_len;
 415         if (page_pos >= 0 && page_pos < outbuf->page_len) {
 416                 /* pages are not in place: */
 417                 int i = (page_pos + outbuf->page_base) >> PAGE_CACHE_SHIFT;
 418                 in_page = desc->pages[i];
 419         } else {
 420                 in_page = sg_page(sg);
 421         }
 422         sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length,
 423                     sg->offset);
 424         sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length,
 425                     sg->offset);
 426         desc->fragno++;
 427         desc->fraglen += sg->length;
 428         desc->pos += sg->length;
 429
 430         fraglen = thislen & (crypto_blkcipher_blocksize(desc->desc.tfm) - 1);
 431         thislen -= fraglen;
 432
 433         if (thislen == 0)
 434                 return 0;
 435
 436         sg_mark_end(&desc->infrags[desc->fragno - 1]);
 437         sg_mark_end(&desc->outfrags[desc->fragno - 1]);
 438
 439         ret = crypto_blkcipher_encrypt_iv(&desc->desc, desc->outfrags,
 440                                           desc->infrags, thislen);
 441         if (ret)
 442                 return ret;
 443
 444         sg_init_table(desc->infrags, 4);
 445         sg_init_table(desc->outfrags, 4);
 446
 447         if (fraglen) {
 448                 sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen,
 449                                 sg->offset + sg->length - fraglen);
 450                 desc->infrags[0] = desc->outfrags[0];
 451                 sg_assign_page(&desc->infrags[0], in_page);
 452                 desc->fragno = 1;
 453                 desc->fraglen = fraglen;
 454         } else {
 455                 desc->fragno = 0;
 456                 desc->fraglen = 0;
 457         }
 458         return 0;
 459 }
 460
 461 int
 462 gss_encrypt_xdr_buf(struct crypto_blkcipher *tfm, struct xdr_buf *buf,
 463                     int offset, struct page **pages)
 464 {
 465         int ret;
 466         struct encryptor_desc desc;
 467
 468         BUG_ON((buf->len - offset) % crypto_blkcipher_blocksize(tfm) != 0);
 469
 470         memset(desc.iv, 0, sizeof(desc.iv));
 471         desc.desc.tfm = tfm;
 472         desc.desc.info = desc.iv;
 473         desc.desc.flags = 0;
 474         desc.pos = offset;
 475         desc.outbuf = buf;
 476         desc.pages = pages;
 477         desc.fragno = 0;
 478         desc.fraglen = 0;
 479
 480         sg_init_table(desc.infrags, 4);
 481         sg_init_table(desc.outfrags, 4);
 482
 483         ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc);
 484         return ret;
 485 }
 486
 487 struct decryptor_desc {
 488         u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
 489         struct blkcipher_desc desc;
 490         struct scatterlist frags[4];
 491         int fragno;
 492         int fraglen;
 493 };
 494
 495 static int
 496 decryptor(struct scatterlist *sg, void *data)
 497 {
 498         struct decryptor_desc *desc = data;
 499         int thislen = desc->fraglen + sg->length;
 500         int fraglen, ret;
 501
 502         /* Worst case is 4 fragments: head, end of page 1, start
 503          * of page 2, tail.  Anything more is a bug. */
 504         BUG_ON(desc->fragno > 3);
 505         sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length,
 506                     sg->offset);
 507         desc->fragno++;
 508         desc->fraglen += sg->length;
 509
 510         fraglen = thislen & (crypto_blkcipher_blocksize(desc->desc.tfm) - 1);
 511         thislen -= fraglen;
 512
 513         if (thislen == 0)
 514                 return 0;
 515
 516         sg_mark_end(&desc->frags[desc->fragno - 1]);
 517
 518         ret = crypto_blkcipher_decrypt_iv(&desc->desc, desc->frags,
 519                                           desc->frags, thislen);
 520         if (ret)
 521                 return ret;
 522
 523         sg_init_table(desc->frags, 4);
 524
 525         if (fraglen) {
 526                 sg_set_page(&desc->frags[0], sg_page(sg), fraglen,
 527                                 sg->offset + sg->length - fraglen);
 528                 desc->fragno = 1;
 529                 desc->fraglen = fraglen;
 530         } else {
 531                 desc->fragno = 0;
 532                 desc->fraglen = 0;
 533         }
 534         return 0;
 535 }
 536
 537 int
 538 gss_decrypt_xdr_buf(struct crypto_blkcipher *tfm, struct xdr_buf *buf,
 539                     int offset)
 540 {
 541         struct decryptor_desc desc;
 542
 543         /* XXXJBF: */
 544         BUG_ON((buf->len - offset) % crypto_blkcipher_blocksize(tfm) != 0);
 545
 546         memset(desc.iv, 0, sizeof(desc.iv));
 547         desc.desc.tfm = tfm;
 548         desc.desc.info = desc.iv;
 549         desc.desc.flags = 0;
 550         desc.fragno = 0;
 551         desc.fraglen = 0;
 552
 553         sg_init_table(desc.frags, 4);
 554
 555         return xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
 556 }
 557
 558 /*
 559  * This function makes the assumption that it was ultimately called
 560  * from gss_wrap().
 561  *
 562  * The client auth_gss code moves any existing tail data into a
 563  * separate page before calling gss_wrap.
 564  * The server svcauth_gss code ensures that both the head and the
 565  * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
 566  *
 567  * Even with that guarantee, this function may be called more than
 568  * once in the processing of gss_wrap().  The best we can do is
 569  * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
 570  * largest expected shift will fit within RPC_MAX_AUTH_SIZE.
 571  * At run-time we can verify that a single invocation of this
 572  * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
 573  */
 574
 575 int
 576 xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
 577 {
 578         u8 *p;
 579
 580         if (shiftlen == 0)
 581                 return 0;
 582
 583         BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE);
 584         BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
 585
 586         p = buf->head[0].iov_base + base;
 587
 588         memmove(p + shiftlen, p, buf->head[0].iov_len - base);
 589
 590         buf->head[0].iov_len += shiftlen;
 591         buf->len += shiftlen;
 592
 593         return 0;
 594 }
 595
 596 static u32
 597 gss_krb5_cts_crypt(struct crypto_blkcipher *cipher, struct xdr_buf *buf,
 598                    u32 offset, u8 *iv, struct page **pages, int encrypt)
 599 {
 600         u32 ret;
 601         struct scatterlist sg[1];
 602         struct blkcipher_desc desc = { .tfm = cipher, .info = iv };
 603         u8 data[GSS_KRB5_MAX_BLOCKSIZE * 2];
 604         struct page **save_pages;
 605         u32 len = buf->len - offset;
 606
 607         if (len > ARRAY_SIZE(data)) {
 608                 WARN_ON(0);
 609                 return -ENOMEM;
 610         }
 611
 612         /*
 613          * For encryption, we want to read from the cleartext
 614          * page cache pages, and write the encrypted data to
 615          * the supplied xdr_buf pages.
 616          */
 617         save_pages = buf->pages;
 618         if (encrypt)
 619                 buf->pages = pages;
 620
 621         ret = read_bytes_from_xdr_buf(buf, offset, data, len);
 622         buf->pages = save_pages;
 623         if (ret)
 624                 goto out;
 625
 626         sg_init_one(sg, data, len);
 627
 628         if (encrypt)
 629                 ret = crypto_blkcipher_encrypt_iv(&desc, sg, sg, len);
 630         else
 631                 ret = crypto_blkcipher_decrypt_iv(&desc, sg, sg, len);
 632
 633         if (ret)
 634                 goto out;
 635
 636         ret = write_bytes_to_xdr_buf(buf, offset, data, len);
 637
 638 out:
 639         return ret;
 640 }
 641
 642 u32
 643 gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
 644                      struct xdr_buf *buf, int ec, struct page **pages)
 645 {
 646         u32 err;
 647         struct xdr_netobj hmac;
 648         u8 *cksumkey;
 649         u8 *ecptr;
 650         struct crypto_blkcipher *cipher, *aux_cipher;
 651         int blocksize;
 652         struct page **save_pages;
 653         int nblocks, nbytes;
 654         struct encryptor_desc desc;
 655         u32 cbcbytes;
 656         unsigned int usage;
 657
 658         if (kctx->initiate) {
 659                 cipher = kctx->initiator_enc;
 660                 aux_cipher = kctx->initiator_enc_aux;
 661                 cksumkey = kctx->initiator_integ;
 662                 usage = KG_USAGE_INITIATOR_SEAL;
 663         } else {
 664                 cipher = kctx->acceptor_enc;
 665                 aux_cipher = kctx->acceptor_enc_aux;
 666                 cksumkey = kctx->acceptor_integ;
 667                 usage = KG_USAGE_ACCEPTOR_SEAL;
 668         }
 669         blocksize = crypto_blkcipher_blocksize(cipher);
 670
 671         /* hide the gss token header and insert the confounder */
 672         offset += GSS_KRB5_TOK_HDR_LEN;
 673         if (xdr_extend_head(buf, offset, kctx->gk5e->conflen))
 674                 return GSS_S_FAILURE;
 675         gss_krb5_make_confounder(buf->head[0].iov_base + offset, kctx->gk5e->conflen);
 676         offset -= GSS_KRB5_TOK_HDR_LEN;
 677
 678         if (buf->tail[0].iov_base != NULL) {
 679                 ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
 680         } else {
 681                 buf->tail[0].iov_base = buf->head[0].iov_base
 682                                                         + buf->head[0].iov_len;
 683                 buf->tail[0].iov_len = 0;
 684                 ecptr = buf->tail[0].iov_base;
 685         }
 686
 687         memset(ecptr, 'X', ec);
 688         buf->tail[0].iov_len += ec;
 689         buf->len += ec;
 690
 691         /* copy plaintext gss token header after filler (if any) */
 692         memcpy(ecptr + ec, buf->head[0].iov_base + offset,
 693                                                 GSS_KRB5_TOK_HDR_LEN);
 694         buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
 695         buf->len += GSS_KRB5_TOK_HDR_LEN;
 696
 697         /* Do the HMAC */
 698         hmac.len = GSS_KRB5_MAX_CKSUM_LEN;
 699         hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
 700
 701         /*
 702          * When we are called, pages points to the real page cache
 703          * data -- which we can't go and encrypt!  buf->pages points
 704          * to scratch pages which we are going to send off to the
 705          * client/server.  Swap in the plaintext pages to calculate
 706          * the hmac.
 707          */
 708         save_pages = buf->pages;
 709         buf->pages = pages;
 710
 711         err = make_checksum_v2(kctx, NULL, 0, buf,
 712                                offset + GSS_KRB5_TOK_HDR_LEN,
 713                                cksumkey, usage, &hmac);
 714         buf->pages = save_pages;
 715         if (err)
 716                 return GSS_S_FAILURE;
 717
 718         nbytes = buf->len - offset - GSS_KRB5_TOK_HDR_LEN;
 719         nblocks = (nbytes + blocksize - 1) / blocksize;
 720         cbcbytes = 0;
 721         if (nblocks > 2)
 722                 cbcbytes = (nblocks - 2) * blocksize;
 723
 724         memset(desc.iv, 0, sizeof(desc.iv));
 725
 726         if (cbcbytes) {
 727                 desc.pos = offset + GSS_KRB5_TOK_HDR_LEN;
 728                 desc.fragno = 0;
 729                 desc.fraglen = 0;
 730                 desc.pages = pages;
 731                 desc.outbuf = buf;
 732                 desc.desc.info = desc.iv;
 733                 desc.desc.flags = 0;
 734                 desc.desc.tfm = aux_cipher;
 735
 736                 sg_init_table(desc.infrags, 4);
 737                 sg_init_table(desc.outfrags, 4);
 738
 739                 err = xdr_process_buf(buf, offset + GSS_KRB5_TOK_HDR_LEN,
 740                                       cbcbytes, encryptor, &desc);
 741                 if (err)
 742                         goto out_err;
 743         }
 744
 745         /* Make sure IV carries forward from any CBC results. */
 746         err = gss_krb5_cts_crypt(cipher, buf,
 747                                  offset + GSS_KRB5_TOK_HDR_LEN + cbcbytes,
 748                                  desc.iv, pages, 1);
 749         if (err) {
 750                 err = GSS_S_FAILURE;
 751                 goto out_err;
 752         }
 753
 754         /* Now update buf to account for HMAC */
 755         buf->tail[0].iov_len += kctx->gk5e->cksumlength;
 756         buf->len += kctx->gk5e->cksumlength;
 757
 758 out_err:
 759         if (err)
 760                 err = GSS_S_FAILURE;
 761         return err;
 762 }
 763
 764 u32
 765 gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
 766                      u32 *headskip, u32 *tailskip)
 767 {
 768         struct xdr_buf subbuf;
 769         u32 ret = 0;
 770         u8 *cksum_key;
 771         struct crypto_blkcipher *cipher, *aux_cipher;
 772         struct xdr_netobj our_hmac_obj;
 773         u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
 774         u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
 775         int nblocks, blocksize, cbcbytes;
 776         struct decryptor_desc desc;
 777         unsigned int usage;
 778
 779         if (kctx->initiate) {
 780                 cipher = kctx->acceptor_enc;
 781                 aux_cipher = kctx->acceptor_enc_aux;
 782                 cksum_key = kctx->acceptor_integ;
 783                 usage = KG_USAGE_ACCEPTOR_SEAL;
 784         } else {
 785                 cipher = kctx->initiator_enc;
 786                 aux_cipher = kctx->initiator_enc_aux;
 787                 cksum_key = kctx->initiator_integ;
 788                 usage = KG_USAGE_INITIATOR_SEAL;
 789         }
 790         blocksize = crypto_blkcipher_blocksize(cipher);
 791
 792
 793         /* create a segment skipping the header and leaving out the checksum */
 794         xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
 795                                     (buf->len - offset - GSS_KRB5_TOK_HDR_LEN -
 796                                      kctx->gk5e->cksumlength));
 797
 798         nblocks = (subbuf.len + blocksize - 1) / blocksize;
 799
 800         cbcbytes = 0;
 801         if (nblocks > 2)
 802                 cbcbytes = (nblocks - 2) * blocksize;
 803
 804         memset(desc.iv, 0, sizeof(desc.iv));
 805
 806         if (cbcbytes) {
 807                 desc.fragno = 0;
 808                 desc.fraglen = 0;
 809                 desc.desc.info = desc.iv;
 810                 desc.desc.flags = 0;
 811                 desc.desc.tfm = aux_cipher;
 812
 813                 sg_init_table(desc.frags, 4);
 814
 815                 ret = xdr_process_buf(&subbuf, 0, cbcbytes, decryptor, &desc);
 816                 if (ret)
 817                         goto out_err;
 818         }
 819
 820         /* Make sure IV carries forward from any CBC results. */
 821         ret = gss_krb5_cts_crypt(cipher, &subbuf, cbcbytes, desc.iv, NULL, 0);
 822         if (ret)
 823                 goto out_err;
 824
 825
 826         /* Calculate our hmac over the plaintext data */
 827         our_hmac_obj.len = sizeof(our_hmac);
 828         our_hmac_obj.data = our_hmac;
 829
 830         ret = make_checksum_v2(kctx, NULL, 0, &subbuf, 0,
 831                                cksum_key, usage, &our_hmac_obj);
 832         if (ret)
 833                 goto out_err;
 834
 835         /* Get the packet's hmac value */
 836         ret = read_bytes_from_xdr_buf(buf, buf->len - kctx->gk5e->cksumlength,
 837                                       pkt_hmac, kctx->gk5e->cksumlength);
 838         if (ret)
 839                 goto out_err;
 840
 841         if (memcmp(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
 842                 ret = GSS_S_BAD_SIG;
 843                 goto out_err;
 844         }
 845         *headskip = kctx->gk5e->conflen;
 846         *tailskip = kctx->gk5e->cksumlength;
 847 out_err:
 848         if (ret && ret != GSS_S_BAD_SIG)
 849                 ret = GSS_S_FAILURE;
 850         return ret;
 851 }
 852
 853 /*
 854  * Compute Kseq given the initial session key and the checksum.
 855  * Set the key of the given cipher.
 856  */
 857 int
 858 krb5_rc4_setup_seq_key(struct krb5_ctx *kctx, struct crypto_blkcipher *cipher,
 859                        unsigned char *cksum)
 860 {
 861         struct crypto_hash *hmac;
 862         struct hash_desc desc;
 863         struct scatterlist sg[1];
 864         u8 Kseq[GSS_KRB5_MAX_KEYLEN];
 865         u32 zeroconstant = 0;
 866         int err;
 867
 868         dprintk("%s: entered\n", __func__);
 869
 870         hmac = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
 871         if (IS_ERR(hmac)) {
 872                 dprintk("%s: error %ld, allocating hash '%s'\n",
 873                         __func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
 874                 return PTR_ERR(hmac);
 875         }
 876
 877         desc.tfm = hmac;
 878         desc.flags = 0;
 879
 880         err = crypto_hash_init(&desc);
 881         if (err)
 882                 goto out_err;
 883
 884         /* Compute intermediate Kseq from session key */
 885         err = crypto_hash_setkey(hmac, kctx->Ksess, kctx->gk5e->keylength);
 886         if (err)
 887                 goto out_err;
 888
 889         sg_init_table(sg, 1);
 890         sg_set_buf(sg, &zeroconstant, 4);
 891
 892         err = crypto_hash_digest(&desc, sg, 4, Kseq);
 893         if (err)
 894                 goto out_err;
 895
 896         /* Compute final Kseq from the checksum and intermediate Kseq */
 897         err = crypto_hash_setkey(hmac, Kseq, kctx->gk5e->keylength);
 898         if (err)
 899                 goto out_err;
 900
 901         sg_set_buf(sg, cksum, 8);
 902
 903         err = crypto_hash_digest(&desc, sg, 8, Kseq);
 904         if (err)
 905                 goto out_err;
 906
 907         err = crypto_blkcipher_setkey(cipher, Kseq, kctx->gk5e->keylength);
 908         if (err)
 909                 goto out_err;
 910
 911         err = 0;
 912
 913 out_err:
 914         crypto_free_hash(hmac);
 915         dprintk("%s: returning %d\n", __func__, err);
 916         return err;
 917 }
 918
 919 /*
 920  * Compute Kcrypt given the initial session key and the plaintext seqnum.
 921  * Set the key of cipher kctx->enc.
 922  */
 923 int
 924 krb5_rc4_setup_enc_key(struct krb5_ctx *kctx, struct crypto_blkcipher *cipher,
 925                        s32 seqnum)
 926 {
 927         struct crypto_hash *hmac;
 928         struct hash_desc desc;
 929         struct scatterlist sg[1];
 930         u8 Kcrypt[GSS_KRB5_MAX_KEYLEN];
 931         u8 zeroconstant[4] = {0};
 932         u8 seqnumarray[4];
 933         int err, i;
 934
 935         dprintk("%s: entered, seqnum %u\n", __func__, seqnum);
 936
 937         hmac = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
 938         if (IS_ERR(hmac)) {
 939                 dprintk("%s: error %ld, allocating hash '%s'\n",
 940                         __func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
 941                 return PTR_ERR(hmac);
 942         }
 943
 944         desc.tfm = hmac;
 945         desc.flags = 0;
 946
 947         err = crypto_hash_init(&desc);
 948         if (err)
 949                 goto out_err;
 950
 951         /* Compute intermediate Kcrypt from session key */
 952         for (i = 0; i < kctx->gk5e->keylength; i++)
 953                 Kcrypt[i] = kctx->Ksess[i] ^ 0xf0;
 954
 955         err = crypto_hash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
 956         if (err)
 957                 goto out_err;
 958
 959         sg_init_table(sg, 1);
 960         sg_set_buf(sg, zeroconstant, 4);
 961
 962         err = crypto_hash_digest(&desc, sg, 4, Kcrypt);
 963         if (err)
 964                 goto out_err;
 965
 966         /* Compute final Kcrypt from the seqnum and intermediate Kcrypt */
 967         err = crypto_hash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
 968         if (err)
 969                 goto out_err;
 970
 971         seqnumarray[0] = (unsigned char) ((seqnum >> 24) & 0xff);
 972         seqnumarray[1] = (unsigned char) ((seqnum >> 16) & 0xff);
 973         seqnumarray[2] = (unsigned char) ((seqnum >> 8) & 0xff);
 974         seqnumarray[3] = (unsigned char) ((seqnum >> 0) & 0xff);
 975
 976         sg_set_buf(sg, seqnumarray, 4);
 977
 978         err = crypto_hash_digest(&desc, sg, 4, Kcrypt);
 979         if (err)
 980                 goto out_err;
 981
 982         err = crypto_blkcipher_setkey(cipher, Kcrypt, kctx->gk5e->keylength);
 983         if (err)
 984                 goto out_err;
 985
 986         err = 0;
 987
 988 out_err:
 989         crypto_free_hash(hmac);
 990         dprintk("%s: returning %d\n", __func__, err);
 991         return err;
 992 }
 993