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 <crypto/hash.h>
  38 #include <crypto/skcipher.h>
  39 #include <linux/err.h>
  40 #include <linux/types.h>
  41 #include <linux/mm.h>
  42 #include <linux/scatterlist.h>
  43 #include <linux/highmem.h>
  44 #include <linux/pagemap.h>
  45 #include <linux/random.h>
  46 #include <linux/sunrpc/gss_krb5.h>
  47 #include <linux/sunrpc/xdr.h>
  48
  49 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  50 # define RPCDBG_FACILITY        RPCDBG_AUTH
  51 #endif
  52
  53 u32
  54 krb5_encrypt(
  55         struct crypto_skcipher *tfm,
  56         void * iv,
  57         void * in,
  58         void * out,
  59         int length)
  60 {
  61         u32 ret = -EINVAL;
  62         struct scatterlist sg[1];
  63         u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
  64         SKCIPHER_REQUEST_ON_STACK(req, tfm);
  65
  66         if (length % crypto_skcipher_blocksize(tfm) != 0)
  67                 goto out;
  68
  69         if (crypto_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
  70                 dprintk("RPC:       gss_k5encrypt: tfm iv size too large %d\n",
  71                         crypto_skcipher_ivsize(tfm));
  72                 goto out;
  73         }
  74
  75         if (iv)
  76                 memcpy(local_iv, iv, crypto_skcipher_ivsize(tfm));
  77
  78         memcpy(out, in, length);
  79         sg_init_one(sg, out, length);
  80
  81         skcipher_request_set_tfm(req, tfm);
  82         skcipher_request_set_callback(req, 0, NULL, NULL);
  83         skcipher_request_set_crypt(req, sg, sg, length, local_iv);
  84
  85         ret = crypto_skcipher_encrypt(req);
  86         skcipher_request_zero(req);
  87 out:
  88         dprintk("RPC:       krb5_encrypt returns %d\n", ret);
  89         return ret;
  90 }
  91
  92 u32
  93 krb5_decrypt(
  94      struct crypto_skcipher *tfm,
  95      void * iv,
  96      void * in,
  97      void * out,
  98      int length)
  99 {
 100         u32 ret = -EINVAL;
 101         struct scatterlist sg[1];
 102         u8 local_iv[GSS_KRB5_MAX_BLOCKSIZE] = {0};
 103         SKCIPHER_REQUEST_ON_STACK(req, tfm);
 104
 105         if (length % crypto_skcipher_blocksize(tfm) != 0)
 106                 goto out;
 107
 108         if (crypto_skcipher_ivsize(tfm) > GSS_KRB5_MAX_BLOCKSIZE) {
 109                 dprintk("RPC:       gss_k5decrypt: tfm iv size too large %d\n",
 110                         crypto_skcipher_ivsize(tfm));
 111                 goto out;
 112         }
 113         if (iv)
 114                 memcpy(local_iv,iv, crypto_skcipher_ivsize(tfm));
 115
 116         memcpy(out, in, length);
 117         sg_init_one(sg, out, length);
 118
 119         skcipher_request_set_tfm(req, tfm);
 120         skcipher_request_set_callback(req, 0, NULL, NULL);
 121         skcipher_request_set_crypt(req, sg, sg, length, local_iv);
 122
 123         ret = crypto_skcipher_decrypt(req);
 124         skcipher_request_zero(req);
 125 out:
 126         dprintk("RPC:       gss_k5decrypt returns %d\n",ret);
 127         return ret;
 128 }
 129
 130 static int
 131 checksummer(struct scatterlist *sg, void *data)
 132 {
 133         struct ahash_request *req = data;
 134
 135         ahash_request_set_crypt(req, sg, NULL, sg->length);
 136
 137         return crypto_ahash_update(req);
 138 }
 139
 140 static int
 141 arcfour_hmac_md5_usage_to_salt(unsigned int usage, u8 salt[4])
 142 {
 143         unsigned int ms_usage;
 144
 145         switch (usage) {
 146         case KG_USAGE_SIGN:
 147                 ms_usage = 15;
 148                 break;
 149         case KG_USAGE_SEAL:
 150                 ms_usage = 13;
 151                 break;
 152         default:
 153                 return -EINVAL;
 154         }
 155         salt[0] = (ms_usage >> 0) & 0xff;
 156         salt[1] = (ms_usage >> 8) & 0xff;
 157         salt[2] = (ms_usage >> 16) & 0xff;
 158         salt[3] = (ms_usage >> 24) & 0xff;
 159
 160         return 0;
 161 }
 162
 163 static u32
 164 make_checksum_hmac_md5(struct krb5_ctx *kctx, char *header, int hdrlen,
 165                        struct xdr_buf *body, int body_offset, u8 *cksumkey,
 166                        unsigned int usage, struct xdr_netobj *cksumout)
 167 {
 168         struct scatterlist              sg[1];
 169         int err = -1;
 170         u8 *checksumdata;
 171         u8 rc4salt[4];
 172         struct crypto_ahash *md5;
 173         struct crypto_ahash *hmac_md5;
 174         struct ahash_request *req;
 175
 176         if (cksumkey == NULL)
 177                 return GSS_S_FAILURE;
 178
 179         if (cksumout->len < kctx->gk5e->cksumlength) {
 180                 dprintk("%s: checksum buffer length, %u, too small for %s\n",
 181                         __func__, cksumout->len, kctx->gk5e->name);
 182                 return GSS_S_FAILURE;
 183         }
 184
 185         if (arcfour_hmac_md5_usage_to_salt(usage, rc4salt)) {
 186                 dprintk("%s: invalid usage value %u\n", __func__, usage);
 187                 return GSS_S_FAILURE;
 188         }
 189
 190         checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
 191         if (!checksumdata)
 192                 return GSS_S_FAILURE;
 193
 194         md5 = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
 195         if (IS_ERR(md5))
 196                 goto out_free_cksum;
 197
 198         hmac_md5 = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0,
 199                                       CRYPTO_ALG_ASYNC);
 200         if (IS_ERR(hmac_md5))
 201                 goto out_free_md5;
 202
 203         req = ahash_request_alloc(md5, GFP_NOFS);
 204         if (!req)
 205                 goto out_free_hmac_md5;
 206
 207         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
 208
 209         err = crypto_ahash_init(req);
 210         if (err)
 211                 goto out;
 212         sg_init_one(sg, rc4salt, 4);
 213         ahash_request_set_crypt(req, sg, NULL, 4);
 214         err = crypto_ahash_update(req);
 215         if (err)
 216                 goto out;
 217
 218         sg_init_one(sg, header, hdrlen);
 219         ahash_request_set_crypt(req, sg, NULL, hdrlen);
 220         err = crypto_ahash_update(req);
 221         if (err)
 222                 goto out;
 223         err = xdr_process_buf(body, body_offset, body->len - body_offset,
 224                               checksummer, req);
 225         if (err)
 226                 goto out;
 227         ahash_request_set_crypt(req, NULL, checksumdata, 0);
 228         err = crypto_ahash_final(req);
 229         if (err)
 230                 goto out;
 231
 232         ahash_request_free(req);
 233         req = ahash_request_alloc(hmac_md5, GFP_NOFS);
 234         if (!req)
 235                 goto out_free_hmac_md5;
 236
 237         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
 238
 239         err = crypto_ahash_init(req);
 240         if (err)
 241                 goto out;
 242         err = crypto_ahash_setkey(hmac_md5, cksumkey, kctx->gk5e->keylength);
 243         if (err)
 244                 goto out;
 245
 246         sg_init_one(sg, checksumdata, crypto_ahash_digestsize(md5));
 247         ahash_request_set_crypt(req, sg, checksumdata,
 248                                 crypto_ahash_digestsize(md5));
 249         err = crypto_ahash_digest(req);
 250         if (err)
 251                 goto out;
 252
 253         memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
 254         cksumout->len = kctx->gk5e->cksumlength;
 255 out:
 256         ahash_request_free(req);
 257 out_free_hmac_md5:
 258         crypto_free_ahash(hmac_md5);
 259 out_free_md5:
 260         crypto_free_ahash(md5);
 261 out_free_cksum:
 262         kfree(checksumdata);
 263         return err ? GSS_S_FAILURE : 0;
 264 }
 265
 266 /*
 267  * checksum the plaintext data and hdrlen bytes of the token header
 268  * The checksum is performed over the first 8 bytes of the
 269  * gss token header and then over the data body
 270  */
 271 u32
 272 make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,
 273               struct xdr_buf *body, int body_offset, u8 *cksumkey,
 274               unsigned int usage, struct xdr_netobj *cksumout)
 275 {
 276         struct crypto_ahash *tfm;
 277         struct ahash_request *req;
 278         struct scatterlist              sg[1];
 279         int err = -1;
 280         u8 *checksumdata;
 281         unsigned int checksumlen;
 282
 283         if (kctx->gk5e->ctype == CKSUMTYPE_HMAC_MD5_ARCFOUR)
 284                 return make_checksum_hmac_md5(kctx, header, hdrlen,
 285                                               body, body_offset,
 286                                               cksumkey, usage, cksumout);
 287
 288         if (cksumout->len < kctx->gk5e->cksumlength) {
 289                 dprintk("%s: checksum buffer length, %u, too small for %s\n",
 290                         __func__, cksumout->len, kctx->gk5e->name);
 291                 return GSS_S_FAILURE;
 292         }
 293
 294         checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
 295         if (checksumdata == NULL)
 296                 return GSS_S_FAILURE;
 297
 298         tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
 299         if (IS_ERR(tfm))
 300                 goto out_free_cksum;
 301
 302         req = ahash_request_alloc(tfm, GFP_NOFS);
 303         if (!req)
 304                 goto out_free_ahash;
 305
 306         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
 307
 308         checksumlen = crypto_ahash_digestsize(tfm);
 309
 310         if (cksumkey != NULL) {
 311                 err = crypto_ahash_setkey(tfm, cksumkey,
 312                                           kctx->gk5e->keylength);
 313                 if (err)
 314                         goto out;
 315         }
 316
 317         err = crypto_ahash_init(req);
 318         if (err)
 319                 goto out;
 320         sg_init_one(sg, header, hdrlen);
 321         ahash_request_set_crypt(req, sg, NULL, hdrlen);
 322         err = crypto_ahash_update(req);
 323         if (err)
 324                 goto out;
 325         err = xdr_process_buf(body, body_offset, body->len - body_offset,
 326                               checksummer, req);
 327         if (err)
 328                 goto out;
 329         ahash_request_set_crypt(req, NULL, checksumdata, 0);
 330         err = crypto_ahash_final(req);
 331         if (err)
 332                 goto out;
 333
 334         switch (kctx->gk5e->ctype) {
 335         case CKSUMTYPE_RSA_MD5:
 336                 err = kctx->gk5e->encrypt(kctx->seq, NULL, checksumdata,
 337                                           checksumdata, checksumlen);
 338                 if (err)
 339                         goto out;
 340                 memcpy(cksumout->data,
 341                        checksumdata + checksumlen - kctx->gk5e->cksumlength,
 342                        kctx->gk5e->cksumlength);
 343                 break;
 344         case CKSUMTYPE_HMAC_SHA1_DES3:
 345                 memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
 346                 break;
 347         default:
 348                 BUG();
 349                 break;
 350         }
 351         cksumout->len = kctx->gk5e->cksumlength;
 352 out:
 353         ahash_request_free(req);
 354 out_free_ahash:
 355         crypto_free_ahash(tfm);
 356 out_free_cksum:
 357         kfree(checksumdata);
 358         return err ? GSS_S_FAILURE : 0;
 359 }
 360
 361 /*
 362  * checksum the plaintext data and hdrlen bytes of the token header
 363  * Per rfc4121, sec. 4.2.4, the checksum is performed over the data
 364  * body then over the first 16 octets of the MIC token
 365  * Inclusion of the header data in the calculation of the
 366  * checksum is optional.
 367  */
 368 u32
 369 make_checksum_v2(struct krb5_ctx *kctx, char *header, int hdrlen,
 370                  struct xdr_buf *body, int body_offset, u8 *cksumkey,
 371                  unsigned int usage, struct xdr_netobj *cksumout)
 372 {
 373         struct crypto_ahash *tfm;
 374         struct ahash_request *req;
 375         struct scatterlist sg[1];
 376         int err = -1;
 377         u8 *checksumdata;
 378         unsigned int checksumlen;
 379
 380         if (kctx->gk5e->keyed_cksum == 0) {
 381                 dprintk("%s: expected keyed hash for %s\n",
 382                         __func__, kctx->gk5e->name);
 383                 return GSS_S_FAILURE;
 384         }
 385         if (cksumkey == NULL) {
 386                 dprintk("%s: no key supplied for %s\n",
 387                         __func__, kctx->gk5e->name);
 388                 return GSS_S_FAILURE;
 389         }
 390
 391         checksumdata = kmalloc(GSS_KRB5_MAX_CKSUM_LEN, GFP_NOFS);
 392         if (!checksumdata)
 393                 return GSS_S_FAILURE;
 394
 395         tfm = crypto_alloc_ahash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);
 396         if (IS_ERR(tfm))
 397                 goto out_free_cksum;
 398         checksumlen = crypto_ahash_digestsize(tfm);
 399
 400         req = ahash_request_alloc(tfm, GFP_NOFS);
 401         if (!req)
 402                 goto out_free_ahash;
 403
 404         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
 405
 406         err = crypto_ahash_setkey(tfm, cksumkey, kctx->gk5e->keylength);
 407         if (err)
 408                 goto out;
 409
 410         err = crypto_ahash_init(req);
 411         if (err)
 412                 goto out;
 413         err = xdr_process_buf(body, body_offset, body->len - body_offset,
 414                               checksummer, req);
 415         if (err)
 416                 goto out;
 417         if (header != NULL) {
 418                 sg_init_one(sg, header, hdrlen);
 419                 ahash_request_set_crypt(req, sg, NULL, hdrlen);
 420                 err = crypto_ahash_update(req);
 421                 if (err)
 422                         goto out;
 423         }
 424         ahash_request_set_crypt(req, NULL, checksumdata, 0);
 425         err = crypto_ahash_final(req);
 426         if (err)
 427                 goto out;
 428
 429         cksumout->len = kctx->gk5e->cksumlength;
 430
 431         switch (kctx->gk5e->ctype) {
 432         case CKSUMTYPE_HMAC_SHA1_96_AES128:
 433         case CKSUMTYPE_HMAC_SHA1_96_AES256:
 434                 /* note that this truncates the hash */
 435                 memcpy(cksumout->data, checksumdata, kctx->gk5e->cksumlength);
 436                 break;
 437         default:
 438                 BUG();
 439                 break;
 440         }
 441 out:
 442         ahash_request_free(req);
 443 out_free_ahash:
 444         crypto_free_ahash(tfm);
 445 out_free_cksum:
 446         kfree(checksumdata);
 447         return err ? GSS_S_FAILURE : 0;
 448 }
 449
 450 struct encryptor_desc {
 451         u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
 452         struct skcipher_request *req;
 453         int pos;
 454         struct xdr_buf *outbuf;
 455         struct page **pages;
 456         struct scatterlist infrags[4];
 457         struct scatterlist outfrags[4];
 458         int fragno;
 459         int fraglen;
 460 };
 461
 462 static int
 463 encryptor(struct scatterlist *sg, void *data)
 464 {
 465         struct encryptor_desc *desc = data;
 466         struct xdr_buf *outbuf = desc->outbuf;
 467         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(desc->req);
 468         struct page *in_page;
 469         int thislen = desc->fraglen + sg->length;
 470         int fraglen, ret;
 471         int page_pos;
 472
 473         /* Worst case is 4 fragments: head, end of page 1, start
 474          * of page 2, tail.  Anything more is a bug. */
 475         BUG_ON(desc->fragno > 3);
 476
 477         page_pos = desc->pos - outbuf->head[0].iov_len;
 478         if (page_pos >= 0 && page_pos < outbuf->page_len) {
 479                 /* pages are not in place: */
 480                 int i = (page_pos + outbuf->page_base) >> PAGE_SHIFT;
 481                 in_page = desc->pages[i];
 482         } else {
 483                 in_page = sg_page(sg);
 484         }
 485         sg_set_page(&desc->infrags[desc->fragno], in_page, sg->length,
 486                     sg->offset);
 487         sg_set_page(&desc->outfrags[desc->fragno], sg_page(sg), sg->length,
 488                     sg->offset);
 489         desc->fragno++;
 490         desc->fraglen += sg->length;
 491         desc->pos += sg->length;
 492
 493         fraglen = thislen & (crypto_skcipher_blocksize(tfm) - 1);
 494         thislen -= fraglen;
 495
 496         if (thislen == 0)
 497                 return 0;
 498
 499         sg_mark_end(&desc->infrags[desc->fragno - 1]);
 500         sg_mark_end(&desc->outfrags[desc->fragno - 1]);
 501
 502         skcipher_request_set_crypt(desc->req, desc->infrags, desc->outfrags,
 503                                    thislen, desc->iv);
 504
 505         ret = crypto_skcipher_encrypt(desc->req);
 506         if (ret)
 507                 return ret;
 508
 509         sg_init_table(desc->infrags, 4);
 510         sg_init_table(desc->outfrags, 4);
 511
 512         if (fraglen) {
 513                 sg_set_page(&desc->outfrags[0], sg_page(sg), fraglen,
 514                                 sg->offset + sg->length - fraglen);
 515                 desc->infrags[0] = desc->outfrags[0];
 516                 sg_assign_page(&desc->infrags[0], in_page);
 517                 desc->fragno = 1;
 518                 desc->fraglen = fraglen;
 519         } else {
 520                 desc->fragno = 0;
 521                 desc->fraglen = 0;
 522         }
 523         return 0;
 524 }
 525
 526 int
 527 gss_encrypt_xdr_buf(struct crypto_skcipher *tfm, struct xdr_buf *buf,
 528                     int offset, struct page **pages)
 529 {
 530         int ret;
 531         struct encryptor_desc desc;
 532         SKCIPHER_REQUEST_ON_STACK(req, tfm);
 533
 534         BUG_ON((buf->len - offset) % crypto_skcipher_blocksize(tfm) != 0);
 535
 536         skcipher_request_set_tfm(req, tfm);
 537         skcipher_request_set_callback(req, 0, NULL, NULL);
 538
 539         memset(desc.iv, 0, sizeof(desc.iv));
 540         desc.req = req;
 541         desc.pos = offset;
 542         desc.outbuf = buf;
 543         desc.pages = pages;
 544         desc.fragno = 0;
 545         desc.fraglen = 0;
 546
 547         sg_init_table(desc.infrags, 4);
 548         sg_init_table(desc.outfrags, 4);
 549
 550         ret = xdr_process_buf(buf, offset, buf->len - offset, encryptor, &desc);
 551         skcipher_request_zero(req);
 552         return ret;
 553 }
 554
 555 struct decryptor_desc {
 556         u8 iv[GSS_KRB5_MAX_BLOCKSIZE];
 557         struct skcipher_request *req;
 558         struct scatterlist frags[4];
 559         int fragno;
 560         int fraglen;
 561 };
 562
 563 static int
 564 decryptor(struct scatterlist *sg, void *data)
 565 {
 566         struct decryptor_desc *desc = data;
 567         int thislen = desc->fraglen + sg->length;
 568         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(desc->req);
 569         int fraglen, ret;
 570
 571         /* Worst case is 4 fragments: head, end of page 1, start
 572          * of page 2, tail.  Anything more is a bug. */
 573         BUG_ON(desc->fragno > 3);
 574         sg_set_page(&desc->frags[desc->fragno], sg_page(sg), sg->length,
 575                     sg->offset);
 576         desc->fragno++;
 577         desc->fraglen += sg->length;
 578
 579         fraglen = thislen & (crypto_skcipher_blocksize(tfm) - 1);
 580         thislen -= fraglen;
 581
 582         if (thislen == 0)
 583                 return 0;
 584
 585         sg_mark_end(&desc->frags[desc->fragno - 1]);
 586
 587         skcipher_request_set_crypt(desc->req, desc->frags, desc->frags,
 588                                    thislen, desc->iv);
 589
 590         ret = crypto_skcipher_decrypt(desc->req);
 591         if (ret)
 592                 return ret;
 593
 594         sg_init_table(desc->frags, 4);
 595
 596         if (fraglen) {
 597                 sg_set_page(&desc->frags[0], sg_page(sg), fraglen,
 598                                 sg->offset + sg->length - fraglen);
 599                 desc->fragno = 1;
 600                 desc->fraglen = fraglen;
 601         } else {
 602                 desc->fragno = 0;
 603                 desc->fraglen = 0;
 604         }
 605         return 0;
 606 }
 607
 608 int
 609 gss_decrypt_xdr_buf(struct crypto_skcipher *tfm, struct xdr_buf *buf,
 610                     int offset)
 611 {
 612         int ret;
 613         struct decryptor_desc desc;
 614         SKCIPHER_REQUEST_ON_STACK(req, tfm);
 615
 616         /* XXXJBF: */
 617         BUG_ON((buf->len - offset) % crypto_skcipher_blocksize(tfm) != 0);
 618
 619         skcipher_request_set_tfm(req, tfm);
 620         skcipher_request_set_callback(req, 0, NULL, NULL);
 621
 622         memset(desc.iv, 0, sizeof(desc.iv));
 623         desc.req = req;
 624         desc.fragno = 0;
 625         desc.fraglen = 0;
 626
 627         sg_init_table(desc.frags, 4);
 628
 629         ret = xdr_process_buf(buf, offset, buf->len - offset, decryptor, &desc);
 630         skcipher_request_zero(req);
 631         return ret;
 632 }
 633
 634 /*
 635  * This function makes the assumption that it was ultimately called
 636  * from gss_wrap().
 637  *
 638  * The client auth_gss code moves any existing tail data into a
 639  * separate page before calling gss_wrap.
 640  * The server svcauth_gss code ensures that both the head and the
 641  * tail have slack space of RPC_MAX_AUTH_SIZE before calling gss_wrap.
 642  *
 643  * Even with that guarantee, this function may be called more than
 644  * once in the processing of gss_wrap().  The best we can do is
 645  * verify at compile-time (see GSS_KRB5_SLACK_CHECK) that the
 646  * largest expected shift will fit within RPC_MAX_AUTH_SIZE.
 647  * At run-time we can verify that a single invocation of this
 648  * function doesn't attempt to use more the RPC_MAX_AUTH_SIZE.
 649  */
 650
 651 int
 652 xdr_extend_head(struct xdr_buf *buf, unsigned int base, unsigned int shiftlen)
 653 {
 654         u8 *p;
 655
 656         if (shiftlen == 0)
 657                 return 0;
 658
 659         BUILD_BUG_ON(GSS_KRB5_MAX_SLACK_NEEDED > RPC_MAX_AUTH_SIZE);
 660         BUG_ON(shiftlen > RPC_MAX_AUTH_SIZE);
 661
 662         p = buf->head[0].iov_base + base;
 663
 664         memmove(p + shiftlen, p, buf->head[0].iov_len - base);
 665
 666         buf->head[0].iov_len += shiftlen;
 667         buf->len += shiftlen;
 668
 669         return 0;
 670 }
 671
 672 static u32
 673 gss_krb5_cts_crypt(struct crypto_skcipher *cipher, struct xdr_buf *buf,
 674                    u32 offset, u8 *iv, struct page **pages, int encrypt)
 675 {
 676         u32 ret;
 677         struct scatterlist sg[1];
 678         SKCIPHER_REQUEST_ON_STACK(req, cipher);
 679         u8 *data;
 680         struct page **save_pages;
 681         u32 len = buf->len - offset;
 682
 683         if (len > GSS_KRB5_MAX_BLOCKSIZE * 2) {
 684                 WARN_ON(0);
 685                 return -ENOMEM;
 686         }
 687         data = kmalloc(GSS_KRB5_MAX_BLOCKSIZE * 2, GFP_NOFS);
 688         if (!data)
 689                 return -ENOMEM;
 690
 691         /*
 692          * For encryption, we want to read from the cleartext
 693          * page cache pages, and write the encrypted data to
 694          * the supplied xdr_buf pages.
 695          */
 696         save_pages = buf->pages;
 697         if (encrypt)
 698                 buf->pages = pages;
 699
 700         ret = read_bytes_from_xdr_buf(buf, offset, data, len);
 701         buf->pages = save_pages;
 702         if (ret)
 703                 goto out;
 704
 705         sg_init_one(sg, data, len);
 706
 707         skcipher_request_set_tfm(req, cipher);
 708         skcipher_request_set_callback(req, 0, NULL, NULL);
 709         skcipher_request_set_crypt(req, sg, sg, len, iv);
 710
 711         if (encrypt)
 712                 ret = crypto_skcipher_encrypt(req);
 713         else
 714                 ret = crypto_skcipher_decrypt(req);
 715
 716         skcipher_request_zero(req);
 717
 718         if (ret)
 719                 goto out;
 720
 721         ret = write_bytes_to_xdr_buf(buf, offset, data, len);
 722
 723 out:
 724         kfree(data);
 725         return ret;
 726 }
 727
 728 u32
 729 gss_krb5_aes_encrypt(struct krb5_ctx *kctx, u32 offset,
 730                      struct xdr_buf *buf, struct page **pages)
 731 {
 732         u32 err;
 733         struct xdr_netobj hmac;
 734         u8 *cksumkey;
 735         u8 *ecptr;
 736         struct crypto_skcipher *cipher, *aux_cipher;
 737         int blocksize;
 738         struct page **save_pages;
 739         int nblocks, nbytes;
 740         struct encryptor_desc desc;
 741         u32 cbcbytes;
 742         unsigned int usage;
 743
 744         if (kctx->initiate) {
 745                 cipher = kctx->initiator_enc;
 746                 aux_cipher = kctx->initiator_enc_aux;
 747                 cksumkey = kctx->initiator_integ;
 748                 usage = KG_USAGE_INITIATOR_SEAL;
 749         } else {
 750                 cipher = kctx->acceptor_enc;
 751                 aux_cipher = kctx->acceptor_enc_aux;
 752                 cksumkey = kctx->acceptor_integ;
 753                 usage = KG_USAGE_ACCEPTOR_SEAL;
 754         }
 755         blocksize = crypto_skcipher_blocksize(cipher);
 756
 757         /* hide the gss token header and insert the confounder */
 758         offset += GSS_KRB5_TOK_HDR_LEN;
 759         if (xdr_extend_head(buf, offset, kctx->gk5e->conflen))
 760                 return GSS_S_FAILURE;
 761         gss_krb5_make_confounder(buf->head[0].iov_base + offset, kctx->gk5e->conflen);
 762         offset -= GSS_KRB5_TOK_HDR_LEN;
 763
 764         if (buf->tail[0].iov_base != NULL) {
 765                 ecptr = buf->tail[0].iov_base + buf->tail[0].iov_len;
 766         } else {
 767                 buf->tail[0].iov_base = buf->head[0].iov_base
 768                                                         + buf->head[0].iov_len;
 769                 buf->tail[0].iov_len = 0;
 770                 ecptr = buf->tail[0].iov_base;
 771         }
 772
 773         /* copy plaintext gss token header after filler (if any) */
 774         memcpy(ecptr, buf->head[0].iov_base + offset, GSS_KRB5_TOK_HDR_LEN);
 775         buf->tail[0].iov_len += GSS_KRB5_TOK_HDR_LEN;
 776         buf->len += GSS_KRB5_TOK_HDR_LEN;
 777
 778         /* Do the HMAC */
 779         hmac.len = GSS_KRB5_MAX_CKSUM_LEN;
 780         hmac.data = buf->tail[0].iov_base + buf->tail[0].iov_len;
 781
 782         /*
 783          * When we are called, pages points to the real page cache
 784          * data -- which we can't go and encrypt!  buf->pages points
 785          * to scratch pages which we are going to send off to the
 786          * client/server.  Swap in the plaintext pages to calculate
 787          * the hmac.
 788          */
 789         save_pages = buf->pages;
 790         buf->pages = pages;
 791
 792         err = make_checksum_v2(kctx, NULL, 0, buf,
 793                                offset + GSS_KRB5_TOK_HDR_LEN,
 794                                cksumkey, usage, &hmac);
 795         buf->pages = save_pages;
 796         if (err)
 797                 return GSS_S_FAILURE;
 798
 799         nbytes = buf->len - offset - GSS_KRB5_TOK_HDR_LEN;
 800         nblocks = (nbytes + blocksize - 1) / blocksize;
 801         cbcbytes = 0;
 802         if (nblocks > 2)
 803                 cbcbytes = (nblocks - 2) * blocksize;
 804
 805         memset(desc.iv, 0, sizeof(desc.iv));
 806
 807         if (cbcbytes) {
 808                 SKCIPHER_REQUEST_ON_STACK(req, aux_cipher);
 809
 810                 desc.pos = offset + GSS_KRB5_TOK_HDR_LEN;
 811                 desc.fragno = 0;
 812                 desc.fraglen = 0;
 813                 desc.pages = pages;
 814                 desc.outbuf = buf;
 815                 desc.req = req;
 816
 817                 skcipher_request_set_tfm(req, aux_cipher);
 818                 skcipher_request_set_callback(req, 0, NULL, NULL);
 819
 820                 sg_init_table(desc.infrags, 4);
 821                 sg_init_table(desc.outfrags, 4);
 822
 823                 err = xdr_process_buf(buf, offset + GSS_KRB5_TOK_HDR_LEN,
 824                                       cbcbytes, encryptor, &desc);
 825                 skcipher_request_zero(req);
 826                 if (err)
 827                         goto out_err;
 828         }
 829
 830         /* Make sure IV carries forward from any CBC results. */
 831         err = gss_krb5_cts_crypt(cipher, buf,
 832                                  offset + GSS_KRB5_TOK_HDR_LEN + cbcbytes,
 833                                  desc.iv, pages, 1);
 834         if (err) {
 835                 err = GSS_S_FAILURE;
 836                 goto out_err;
 837         }
 838
 839         /* Now update buf to account for HMAC */
 840         buf->tail[0].iov_len += kctx->gk5e->cksumlength;
 841         buf->len += kctx->gk5e->cksumlength;
 842
 843 out_err:
 844         if (err)
 845                 err = GSS_S_FAILURE;
 846         return err;
 847 }
 848
 849 u32
 850 gss_krb5_aes_decrypt(struct krb5_ctx *kctx, u32 offset, struct xdr_buf *buf,
 851                      u32 *headskip, u32 *tailskip)
 852 {
 853         struct xdr_buf subbuf;
 854         u32 ret = 0;
 855         u8 *cksum_key;
 856         struct crypto_skcipher *cipher, *aux_cipher;
 857         struct xdr_netobj our_hmac_obj;
 858         u8 our_hmac[GSS_KRB5_MAX_CKSUM_LEN];
 859         u8 pkt_hmac[GSS_KRB5_MAX_CKSUM_LEN];
 860         int nblocks, blocksize, cbcbytes;
 861         struct decryptor_desc desc;
 862         unsigned int usage;
 863
 864         if (kctx->initiate) {
 865                 cipher = kctx->acceptor_enc;
 866                 aux_cipher = kctx->acceptor_enc_aux;
 867                 cksum_key = kctx->acceptor_integ;
 868                 usage = KG_USAGE_ACCEPTOR_SEAL;
 869         } else {
 870                 cipher = kctx->initiator_enc;
 871                 aux_cipher = kctx->initiator_enc_aux;
 872                 cksum_key = kctx->initiator_integ;
 873                 usage = KG_USAGE_INITIATOR_SEAL;
 874         }
 875         blocksize = crypto_skcipher_blocksize(cipher);
 876
 877
 878         /* create a segment skipping the header and leaving out the checksum */
 879         xdr_buf_subsegment(buf, &subbuf, offset + GSS_KRB5_TOK_HDR_LEN,
 880                                     (buf->len - offset - GSS_KRB5_TOK_HDR_LEN -
 881                                      kctx->gk5e->cksumlength));
 882
 883         nblocks = (subbuf.len + blocksize - 1) / blocksize;
 884
 885         cbcbytes = 0;
 886         if (nblocks > 2)
 887                 cbcbytes = (nblocks - 2) * blocksize;
 888
 889         memset(desc.iv, 0, sizeof(desc.iv));
 890
 891         if (cbcbytes) {
 892                 SKCIPHER_REQUEST_ON_STACK(req, aux_cipher);
 893
 894                 desc.fragno = 0;
 895                 desc.fraglen = 0;
 896                 desc.req = req;
 897
 898                 skcipher_request_set_tfm(req, aux_cipher);
 899                 skcipher_request_set_callback(req, 0, NULL, NULL);
 900
 901                 sg_init_table(desc.frags, 4);
 902
 903                 ret = xdr_process_buf(&subbuf, 0, cbcbytes, decryptor, &desc);
 904                 skcipher_request_zero(req);
 905                 if (ret)
 906                         goto out_err;
 907         }
 908
 909         /* Make sure IV carries forward from any CBC results. */
 910         ret = gss_krb5_cts_crypt(cipher, &subbuf, cbcbytes, desc.iv, NULL, 0);
 911         if (ret)
 912                 goto out_err;
 913
 914
 915         /* Calculate our hmac over the plaintext data */
 916         our_hmac_obj.len = sizeof(our_hmac);
 917         our_hmac_obj.data = our_hmac;
 918
 919         ret = make_checksum_v2(kctx, NULL, 0, &subbuf, 0,
 920                                cksum_key, usage, &our_hmac_obj);
 921         if (ret)
 922                 goto out_err;
 923
 924         /* Get the packet's hmac value */
 925         ret = read_bytes_from_xdr_buf(buf, buf->len - kctx->gk5e->cksumlength,
 926                                       pkt_hmac, kctx->gk5e->cksumlength);
 927         if (ret)
 928                 goto out_err;
 929
 930         if (memcmp(pkt_hmac, our_hmac, kctx->gk5e->cksumlength) != 0) {
 931                 ret = GSS_S_BAD_SIG;
 932                 goto out_err;
 933         }
 934         *headskip = kctx->gk5e->conflen;
 935         *tailskip = kctx->gk5e->cksumlength;
 936 out_err:
 937         if (ret && ret != GSS_S_BAD_SIG)
 938                 ret = GSS_S_FAILURE;
 939         return ret;
 940 }
 941
 942 /*
 943  * Compute Kseq given the initial session key and the checksum.
 944  * Set the key of the given cipher.
 945  */
 946 int
 947 krb5_rc4_setup_seq_key(struct krb5_ctx *kctx, struct crypto_skcipher *cipher,
 948                        unsigned char *cksum)
 949 {
 950         struct crypto_shash *hmac;
 951         struct shash_desc *desc;
 952         u8 Kseq[GSS_KRB5_MAX_KEYLEN];
 953         u32 zeroconstant = 0;
 954         int err;
 955
 956         dprintk("%s: entered\n", __func__);
 957
 958         hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
 959         if (IS_ERR(hmac)) {
 960                 dprintk("%s: error %ld, allocating hash '%s'\n",
 961                         __func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
 962                 return PTR_ERR(hmac);
 963         }
 964
 965         desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
 966                        GFP_NOFS);
 967         if (!desc) {
 968                 dprintk("%s: failed to allocate shash descriptor for '%s'\n",
 969                         __func__, kctx->gk5e->cksum_name);
 970                 crypto_free_shash(hmac);
 971                 return -ENOMEM;
 972         }
 973
 974         desc->tfm = hmac;
 975         desc->flags = 0;
 976
 977         /* Compute intermediate Kseq from session key */
 978         err = crypto_shash_setkey(hmac, kctx->Ksess, kctx->gk5e->keylength);
 979         if (err)
 980                 goto out_err;
 981
 982         err = crypto_shash_digest(desc, (u8 *)&zeroconstant, 4, Kseq);
 983         if (err)
 984                 goto out_err;
 985
 986         /* Compute final Kseq from the checksum and intermediate Kseq */
 987         err = crypto_shash_setkey(hmac, Kseq, kctx->gk5e->keylength);
 988         if (err)
 989                 goto out_err;
 990
 991         err = crypto_shash_digest(desc, cksum, 8, Kseq);
 992         if (err)
 993                 goto out_err;
 994
 995         err = crypto_skcipher_setkey(cipher, Kseq, kctx->gk5e->keylength);
 996         if (err)
 997                 goto out_err;
 998
 999         err = 0;
1000
1001 out_err:
1002         kzfree(desc);
1003         crypto_free_shash(hmac);
1004         dprintk("%s: returning %d\n", __func__, err);
1005         return err;
1006 }
1007
1008 /*
1009  * Compute Kcrypt given the initial session key and the plaintext seqnum.
1010  * Set the key of cipher kctx->enc.
1011  */
1012 int
1013 krb5_rc4_setup_enc_key(struct krb5_ctx *kctx, struct crypto_skcipher *cipher,
1014                        s32 seqnum)
1015 {
1016         struct crypto_shash *hmac;
1017         struct shash_desc *desc;
1018         u8 Kcrypt[GSS_KRB5_MAX_KEYLEN];
1019         u8 zeroconstant[4] = {0};
1020         u8 seqnumarray[4];
1021         int err, i;
1022
1023         dprintk("%s: entered, seqnum %u\n", __func__, seqnum);
1024
1025         hmac = crypto_alloc_shash(kctx->gk5e->cksum_name, 0, 0);
1026         if (IS_ERR(hmac)) {
1027                 dprintk("%s: error %ld, allocating hash '%s'\n",
1028                         __func__, PTR_ERR(hmac), kctx->gk5e->cksum_name);
1029                 return PTR_ERR(hmac);
1030         }
1031
1032         desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(hmac),
1033                        GFP_NOFS);
1034         if (!desc) {
1035                 dprintk("%s: failed to allocate shash descriptor for '%s'\n",
1036                         __func__, kctx->gk5e->cksum_name);
1037                 crypto_free_shash(hmac);
1038                 return -ENOMEM;
1039         }
1040
1041         desc->tfm = hmac;
1042         desc->flags = 0;
1043
1044         /* Compute intermediate Kcrypt from session key */
1045         for (i = 0; i < kctx->gk5e->keylength; i++)
1046                 Kcrypt[i] = kctx->Ksess[i] ^ 0xf0;
1047
1048         err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
1049         if (err)
1050                 goto out_err;
1051
1052         err = crypto_shash_digest(desc, zeroconstant, 4, Kcrypt);
1053         if (err)
1054                 goto out_err;
1055
1056         /* Compute final Kcrypt from the seqnum and intermediate Kcrypt */
1057         err = crypto_shash_setkey(hmac, Kcrypt, kctx->gk5e->keylength);
1058         if (err)
1059                 goto out_err;
1060
1061         seqnumarray[0] = (unsigned char) ((seqnum >> 24) & 0xff);
1062         seqnumarray[1] = (unsigned char) ((seqnum >> 16) & 0xff);
1063         seqnumarray[2] = (unsigned char) ((seqnum >> 8) & 0xff);
1064         seqnumarray[3] = (unsigned char) ((seqnum >> 0) & 0xff);
1065
1066         err = crypto_shash_digest(desc, seqnumarray, 4, Kcrypt);
1067         if (err)
1068                 goto out_err;
1069
1070         err = crypto_skcipher_setkey(cipher, Kcrypt, kctx->gk5e->keylength);
1071         if (err)
1072                 goto out_err;
1073
1074         err = 0;
1075
1076 out_err:
1077         kzfree(desc);
1078         crypto_free_shash(hmac);
1079         dprintk("%s: returning %d\n", __func__, err);
1080         return err;
1081 }
1082