security/keys/encrypted-keys/encrypted.c

   1 /*
   2  * Copyright (C) 2010 IBM Corporation
   3  * Copyright (C) 2010 Politecnico di Torino, Italy
   4  *                    TORSEC group -- http://security.polito.it
   5  *
   6  * Authors:
   7  * Mimi Zohar <zohar@us.ibm.com>
   8  * Roberto Sassu <roberto.sassu@polito.it>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation, version 2 of the License.
  13  *
  14  * See Documentation/security/keys-trusted-encrypted.txt
  15  */
  16
  17 #include <linux/uaccess.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/slab.h>
  21 #include <linux/parser.h>
  22 #include <linux/string.h>
  23 #include <linux/err.h>
  24 #include <keys/user-type.h>
  25 #include <keys/trusted-type.h>
  26 #include <keys/encrypted-type.h>
  27 #include <linux/key-type.h>
  28 #include <linux/random.h>
  29 #include <linux/rcupdate.h>
  30 #include <linux/scatterlist.h>
  31 #include <linux/crypto.h>
  32 #include <linux/ctype.h>
  33 #include <crypto/hash.h>
  34 #include <crypto/sha.h>
  35 #include <crypto/aes.h>
  36
  37 #include "encrypted.h"
  38 #include "ecryptfs_format.h"
  39
  40 static const char KEY_TRUSTED_PREFIX[] = "trusted:";
  41 static const char KEY_USER_PREFIX[] = "user:";
  42 static const char hash_alg[] = "sha256";
  43 static const char hmac_alg[] = "hmac(sha256)";
  44 static const char blkcipher_alg[] = "cbc(aes)";
  45 static const char key_format_default[] = "default";
  46 static const char key_format_ecryptfs[] = "ecryptfs";
  47 static unsigned int ivsize;
  48 static int blksize;
  49
  50 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
  51 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
  52 #define KEY_ECRYPTFS_DESC_LEN 16
  53 #define HASH_SIZE SHA256_DIGEST_SIZE
  54 #define MAX_DATA_SIZE 4096
  55 #define MIN_DATA_SIZE  20
  56
  57 struct sdesc {
  58         struct shash_desc shash;
  59         char ctx[];
  60 };
  61
  62 static struct crypto_shash *hashalg;
  63 static struct crypto_shash *hmacalg;
  64
  65 enum {
  66         Opt_err = -1, Opt_new, Opt_load, Opt_update
  67 };
  68
  69 enum {
  70         Opt_error = -1, Opt_default, Opt_ecryptfs
  71 };
  72
  73 static const match_table_t key_format_tokens = {
  74         {Opt_default, "default"},
  75         {Opt_ecryptfs, "ecryptfs"},
  76         {Opt_error, NULL}
  77 };
  78
  79 static const match_table_t key_tokens = {
  80         {Opt_new, "new"},
  81         {Opt_load, "load"},
  82         {Opt_update, "update"},
  83         {Opt_err, NULL}
  84 };
  85
  86 static int aes_get_sizes(void)
  87 {
  88         struct crypto_blkcipher *tfm;
  89
  90         tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
  91         if (IS_ERR(tfm)) {
  92                 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
  93                        PTR_ERR(tfm));
  94                 return PTR_ERR(tfm);
  95         }
  96         ivsize = crypto_blkcipher_ivsize(tfm);
  97         blksize = crypto_blkcipher_blocksize(tfm);
  98         crypto_free_blkcipher(tfm);
  99         return 0;
 100 }
 101
 102 /*
 103  * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
 104  *
 105  * The description of a encrypted key with format 'ecryptfs' must contain
 106  * exactly 16 hexadecimal characters.
 107  *
 108  */
 109 static int valid_ecryptfs_desc(const char *ecryptfs_desc)
 110 {
 111         int i;
 112
 113         if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
 114                 pr_err("encrypted_key: key description must be %d hexadecimal "
 115                        "characters long\n", KEY_ECRYPTFS_DESC_LEN);
 116                 return -EINVAL;
 117         }
 118
 119         for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
 120                 if (!isxdigit(ecryptfs_desc[i])) {
 121                         pr_err("encrypted_key: key description must contain "
 122                                "only hexadecimal characters\n");
 123                         return -EINVAL;
 124                 }
 125         }
 126
 127         return 0;
 128 }
 129
 130 /*
 131  * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
 132  *
 133  * key-type:= "trusted:" | "user:"
 134  * desc:= master-key description
 135  *
 136  * Verify that 'key-type' is valid and that 'desc' exists. On key update,
 137  * only the master key description is permitted to change, not the key-type.
 138  * The key-type remains constant.
 139  *
 140  * On success returns 0, otherwise -EINVAL.
 141  */
 142 static int valid_master_desc(const char *new_desc, const char *orig_desc)
 143 {
 144         if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
 145                 if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
 146                         goto out;
 147                 if (orig_desc)
 148                         if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
 149                                 goto out;
 150         } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
 151                 if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
 152                         goto out;
 153                 if (orig_desc)
 154                         if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
 155                                 goto out;
 156         } else
 157                 goto out;
 158         return 0;
 159 out:
 160         return -EINVAL;
 161 }
 162
 163 /*
 164  * datablob_parse - parse the keyctl data
 165  *
 166  * datablob format:
 167  * new [<format>] <master-key name> <decrypted data length>
 168  * load [<format>] <master-key name> <decrypted data length>
 169  *     <encrypted iv + data>
 170  * update <new-master-key name>
 171  *
 172  * Tokenizes a copy of the keyctl data, returning a pointer to each token,
 173  * which is null terminated.
 174  *
 175  * On success returns 0, otherwise -EINVAL.
 176  */
 177 static int datablob_parse(char *datablob, const char **format,
 178                           char **master_desc, char **decrypted_datalen,
 179                           char **hex_encoded_iv)
 180 {
 181         substring_t args[MAX_OPT_ARGS];
 182         int ret = -EINVAL;
 183         int key_cmd;
 184         int key_format;
 185         char *p, *keyword;
 186
 187         keyword = strsep(&datablob, " \t");
 188         if (!keyword) {
 189                 pr_info("encrypted_key: insufficient parameters specified\n");
 190                 return ret;
 191         }
 192         key_cmd = match_token(keyword, key_tokens, args);
 193
 194         /* Get optional format: default | ecryptfs */
 195         p = strsep(&datablob, " \t");
 196         if (!p) {
 197                 pr_err("encrypted_key: insufficient parameters specified\n");
 198                 return ret;
 199         }
 200
 201         key_format = match_token(p, key_format_tokens, args);
 202         switch (key_format) {
 203         case Opt_ecryptfs:
 204         case Opt_default:
 205                 *format = p;
 206                 *master_desc = strsep(&datablob, " \t");
 207                 break;
 208         case Opt_error:
 209                 *master_desc = p;
 210                 break;
 211         }
 212
 213         if (!*master_desc) {
 214                 pr_info("encrypted_key: master key parameter is missing\n");
 215                 goto out;
 216         }
 217
 218         if (valid_master_desc(*master_desc, NULL) < 0) {
 219                 pr_info("encrypted_key: master key parameter \'%s\' "
 220                         "is invalid\n", *master_desc);
 221                 goto out;
 222         }
 223
 224         if (decrypted_datalen) {
 225                 *decrypted_datalen = strsep(&datablob, " \t");
 226                 if (!*decrypted_datalen) {
 227                         pr_info("encrypted_key: keylen parameter is missing\n");
 228                         goto out;
 229                 }
 230         }
 231
 232         switch (key_cmd) {
 233         case Opt_new:
 234                 if (!decrypted_datalen) {
 235                         pr_info("encrypted_key: keyword \'%s\' not allowed "
 236                                 "when called from .update method\n", keyword);
 237                         break;
 238                 }
 239                 ret = 0;
 240                 break;
 241         case Opt_load:
 242                 if (!decrypted_datalen) {
 243                         pr_info("encrypted_key: keyword \'%s\' not allowed "
 244                                 "when called from .update method\n", keyword);
 245                         break;
 246                 }
 247                 *hex_encoded_iv = strsep(&datablob, " \t");
 248                 if (!*hex_encoded_iv) {
 249                         pr_info("encrypted_key: hex blob is missing\n");
 250                         break;
 251                 }
 252                 ret = 0;
 253                 break;
 254         case Opt_update:
 255                 if (decrypted_datalen) {
 256                         pr_info("encrypted_key: keyword \'%s\' not allowed "
 257                                 "when called from .instantiate method\n",
 258                                 keyword);
 259                         break;
 260                 }
 261                 ret = 0;
 262                 break;
 263         case Opt_err:
 264                 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
 265                         keyword);
 266                 break;
 267         }
 268 out:
 269         return ret;
 270 }
 271
 272 /*
 273  * datablob_format - format as an ascii string, before copying to userspace
 274  */
 275 static char *datablob_format(struct encrypted_key_payload *epayload,
 276                              size_t asciiblob_len)
 277 {
 278         char *ascii_buf, *bufp;
 279         u8 *iv = epayload->iv;
 280         int len;
 281         int i;
 282
 283         ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
 284         if (!ascii_buf)
 285                 goto out;
 286
 287         ascii_buf[asciiblob_len] = '\0';
 288
 289         /* copy datablob master_desc and datalen strings */
 290         len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
 291                       epayload->master_desc, epayload->datalen);
 292
 293         /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
 294         bufp = &ascii_buf[len];
 295         for (i = 0; i < (asciiblob_len - len) / 2; i++)
 296                 bufp = pack_hex_byte(bufp, iv[i]);
 297 out:
 298         return ascii_buf;
 299 }
 300
 301 /*
 302  * request_user_key - request the user key
 303  *
 304  * Use a user provided key to encrypt/decrypt an encrypted-key.
 305  */
 306 static struct key *request_user_key(const char *master_desc, u8 **master_key,
 307                                     size_t *master_keylen)
 308 {
 309         struct user_key_payload *upayload;
 310         struct key *ukey;
 311
 312         ukey = request_key(&key_type_user, master_desc, NULL);
 313         if (IS_ERR(ukey))
 314                 goto error;
 315
 316         down_read(&ukey->sem);
 317         upayload = rcu_dereference(ukey->payload.data);
 318         *master_key = upayload->data;
 319         *master_keylen = upayload->datalen;
 320 error:
 321         return ukey;
 322 }
 323
 324 static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
 325 {
 326         struct sdesc *sdesc;
 327         int size;
 328
 329         size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
 330         sdesc = kmalloc(size, GFP_KERNEL);
 331         if (!sdesc)
 332                 return ERR_PTR(-ENOMEM);
 333         sdesc->shash.tfm = alg;
 334         sdesc->shash.flags = 0x0;
 335         return sdesc;
 336 }
 337
 338 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
 339                      const u8 *buf, unsigned int buflen)
 340 {
 341         struct sdesc *sdesc;
 342         int ret;
 343
 344         sdesc = alloc_sdesc(hmacalg);
 345         if (IS_ERR(sdesc)) {
 346                 pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
 347                 return PTR_ERR(sdesc);
 348         }
 349
 350         ret = crypto_shash_setkey(hmacalg, key, keylen);
 351         if (!ret)
 352                 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
 353         kfree(sdesc);
 354         return ret;
 355 }
 356
 357 static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
 358 {
 359         struct sdesc *sdesc;
 360         int ret;
 361
 362         sdesc = alloc_sdesc(hashalg);
 363         if (IS_ERR(sdesc)) {
 364                 pr_info("encrypted_key: can't alloc %s\n", hash_alg);
 365                 return PTR_ERR(sdesc);
 366         }
 367
 368         ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
 369         kfree(sdesc);
 370         return ret;
 371 }
 372
 373 enum derived_key_type { ENC_KEY, AUTH_KEY };
 374
 375 /* Derive authentication/encryption key from trusted key */
 376 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
 377                            const u8 *master_key, size_t master_keylen)
 378 {
 379         u8 *derived_buf;
 380         unsigned int derived_buf_len;
 381         int ret;
 382
 383         derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
 384         if (derived_buf_len < HASH_SIZE)
 385                 derived_buf_len = HASH_SIZE;
 386
 387         derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
 388         if (!derived_buf) {
 389                 pr_err("encrypted_key: out of memory\n");
 390                 return -ENOMEM;
 391         }
 392         if (key_type)
 393                 strcpy(derived_buf, "AUTH_KEY");
 394         else
 395                 strcpy(derived_buf, "ENC_KEY");
 396
 397         memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
 398                master_keylen);
 399         ret = calc_hash(derived_key, derived_buf, derived_buf_len);
 400         kfree(derived_buf);
 401         return ret;
 402 }
 403
 404 static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key,
 405                                unsigned int key_len, const u8 *iv,
 406                                unsigned int ivsize)
 407 {
 408         int ret;
 409
 410         desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
 411         if (IS_ERR(desc->tfm)) {
 412                 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
 413                        blkcipher_alg, PTR_ERR(desc->tfm));
 414                 return PTR_ERR(desc->tfm);
 415         }
 416         desc->flags = 0;
 417
 418         ret = crypto_blkcipher_setkey(desc->tfm, key, key_len);
 419         if (ret < 0) {
 420                 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
 421                 crypto_free_blkcipher(desc->tfm);
 422                 return ret;
 423         }
 424         crypto_blkcipher_set_iv(desc->tfm, iv, ivsize);
 425         return 0;
 426 }
 427
 428 static struct key *request_master_key(struct encrypted_key_payload *epayload,
 429                                       u8 **master_key, size_t *master_keylen)
 430 {
 431         struct key *mkey = NULL;
 432
 433         if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
 434                      KEY_TRUSTED_PREFIX_LEN)) {
 435                 mkey = request_trusted_key(epayload->master_desc +
 436                                            KEY_TRUSTED_PREFIX_LEN,
 437                                            master_key, master_keylen);
 438         } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
 439                             KEY_USER_PREFIX_LEN)) {
 440                 mkey = request_user_key(epayload->master_desc +
 441                                         KEY_USER_PREFIX_LEN,
 442                                         master_key, master_keylen);
 443         } else
 444                 goto out;
 445
 446         if (IS_ERR(mkey)) {
 447                 int ret = PTR_ERR(epayload);
 448
 449                 if (ret == -ENOTSUPP)
 450                         pr_info("encrypted_key: key %s not supported",
 451                                 epayload->master_desc);
 452                 else
 453                         pr_info("encrypted_key: key %s not found",
 454                                 epayload->master_desc);
 455                 goto out;
 456         }
 457
 458         dump_master_key(*master_key, *master_keylen);
 459 out:
 460         return mkey;
 461 }
 462
 463 /* Before returning data to userspace, encrypt decrypted data. */
 464 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
 465                                const u8 *derived_key,
 466                                unsigned int derived_keylen)
 467 {
 468         struct scatterlist sg_in[2];
 469         struct scatterlist sg_out[1];
 470         struct blkcipher_desc desc;
 471         unsigned int encrypted_datalen;
 472         unsigned int padlen;
 473         char pad[16];
 474         int ret;
 475
 476         encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
 477         padlen = encrypted_datalen - epayload->decrypted_datalen;
 478
 479         ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
 480                                   epayload->iv, ivsize);
 481         if (ret < 0)
 482                 goto out;
 483         dump_decrypted_data(epayload);
 484
 485         memset(pad, 0, sizeof pad);
 486         sg_init_table(sg_in, 2);
 487         sg_set_buf(&sg_in[0], epayload->decrypted_data,
 488                    epayload->decrypted_datalen);
 489         sg_set_buf(&sg_in[1], pad, padlen);
 490
 491         sg_init_table(sg_out, 1);
 492         sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
 493
 494         ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen);
 495         crypto_free_blkcipher(desc.tfm);
 496         if (ret < 0)
 497                 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
 498         else
 499                 dump_encrypted_data(epayload, encrypted_datalen);
 500 out:
 501         return ret;
 502 }
 503
 504 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
 505                                 const u8 *master_key, size_t master_keylen)
 506 {
 507         u8 derived_key[HASH_SIZE];
 508         u8 *digest;
 509         int ret;
 510
 511         ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
 512         if (ret < 0)
 513                 goto out;
 514
 515         digest = epayload->format + epayload->datablob_len;
 516         ret = calc_hmac(digest, derived_key, sizeof derived_key,
 517                         epayload->format, epayload->datablob_len);
 518         if (!ret)
 519                 dump_hmac(NULL, digest, HASH_SIZE);
 520 out:
 521         return ret;
 522 }
 523
 524 /* verify HMAC before decrypting encrypted key */
 525 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
 526                                 const u8 *format, const u8 *master_key,
 527                                 size_t master_keylen)
 528 {
 529         u8 derived_key[HASH_SIZE];
 530         u8 digest[HASH_SIZE];
 531         int ret;
 532         char *p;
 533         unsigned short len;
 534
 535         ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
 536         if (ret < 0)
 537                 goto out;
 538
 539         len = epayload->datablob_len;
 540         if (!format) {
 541                 p = epayload->master_desc;
 542                 len -= strlen(epayload->format) + 1;
 543         } else
 544                 p = epayload->format;
 545
 546         ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
 547         if (ret < 0)
 548                 goto out;
 549         ret = memcmp(digest, epayload->format + epayload->datablob_len,
 550                      sizeof digest);
 551         if (ret) {
 552                 ret = -EINVAL;
 553                 dump_hmac("datablob",
 554                           epayload->format + epayload->datablob_len,
 555                           HASH_SIZE);
 556                 dump_hmac("calc", digest, HASH_SIZE);
 557         }
 558 out:
 559         return ret;
 560 }
 561
 562 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
 563                                const u8 *derived_key,
 564                                unsigned int derived_keylen)
 565 {
 566         struct scatterlist sg_in[1];
 567         struct scatterlist sg_out[2];
 568         struct blkcipher_desc desc;
 569         unsigned int encrypted_datalen;
 570         char pad[16];
 571         int ret;
 572
 573         encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
 574         ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
 575                                   epayload->iv, ivsize);
 576         if (ret < 0)
 577                 goto out;
 578         dump_encrypted_data(epayload, encrypted_datalen);
 579
 580         memset(pad, 0, sizeof pad);
 581         sg_init_table(sg_in, 1);
 582         sg_init_table(sg_out, 2);
 583         sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
 584         sg_set_buf(&sg_out[0], epayload->decrypted_data,
 585                    epayload->decrypted_datalen);
 586         sg_set_buf(&sg_out[1], pad, sizeof pad);
 587
 588         ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen);
 589         crypto_free_blkcipher(desc.tfm);
 590         if (ret < 0)
 591                 goto out;
 592         dump_decrypted_data(epayload);
 593 out:
 594         return ret;
 595 }
 596
 597 /* Allocate memory for decrypted key and datablob. */
 598 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
 599                                                          const char *format,
 600                                                          const char *master_desc,
 601                                                          const char *datalen)
 602 {
 603         struct encrypted_key_payload *epayload = NULL;
 604         unsigned short datablob_len;
 605         unsigned short decrypted_datalen;
 606         unsigned short payload_datalen;
 607         unsigned int encrypted_datalen;
 608         unsigned int format_len;
 609         long dlen;
 610         int ret;
 611
 612         ret = strict_strtol(datalen, 10, &dlen);
 613         if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
 614                 return ERR_PTR(-EINVAL);
 615
 616         format_len = (!format) ? strlen(key_format_default) : strlen(format);
 617         decrypted_datalen = dlen;
 618         payload_datalen = decrypted_datalen;
 619         if (format && !strcmp(format, key_format_ecryptfs)) {
 620                 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
 621                         pr_err("encrypted_key: keylen for the ecryptfs format "
 622                                "must be equal to %d bytes\n",
 623                                ECRYPTFS_MAX_KEY_BYTES);
 624                         return ERR_PTR(-EINVAL);
 625                 }
 626                 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
 627                 payload_datalen = sizeof(struct ecryptfs_auth_tok);
 628         }
 629
 630         encrypted_datalen = roundup(decrypted_datalen, blksize);
 631
 632         datablob_len = format_len + 1 + strlen(master_desc) + 1
 633             + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
 634
 635         ret = key_payload_reserve(key, payload_datalen + datablob_len
 636                                   + HASH_SIZE + 1);
 637         if (ret < 0)
 638                 return ERR_PTR(ret);
 639
 640         epayload = kzalloc(sizeof(*epayload) + payload_datalen +
 641                            datablob_len + HASH_SIZE + 1, GFP_KERNEL);
 642         if (!epayload)
 643                 return ERR_PTR(-ENOMEM);
 644
 645         epayload->payload_datalen = payload_datalen;
 646         epayload->decrypted_datalen = decrypted_datalen;
 647         epayload->datablob_len = datablob_len;
 648         return epayload;
 649 }
 650
 651 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
 652                                  const char *format, const char *hex_encoded_iv)
 653 {
 654         struct key *mkey;
 655         u8 derived_key[HASH_SIZE];
 656         u8 *master_key;
 657         u8 *hmac;
 658         const char *hex_encoded_data;
 659         unsigned int encrypted_datalen;
 660         size_t master_keylen;
 661         size_t asciilen;
 662         int ret;
 663
 664         encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
 665         asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
 666         if (strlen(hex_encoded_iv) != asciilen)
 667                 return -EINVAL;
 668
 669         hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
 670         hex2bin(epayload->iv, hex_encoded_iv, ivsize);
 671         hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen);
 672
 673         hmac = epayload->format + epayload->datablob_len;
 674         hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE);
 675
 676         mkey = request_master_key(epayload, &master_key, &master_keylen);
 677         if (IS_ERR(mkey))
 678                 return PTR_ERR(mkey);
 679
 680         ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
 681         if (ret < 0) {
 682                 pr_err("encrypted_key: bad hmac (%d)\n", ret);
 683                 goto out;
 684         }
 685
 686         ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
 687         if (ret < 0)
 688                 goto out;
 689
 690         ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
 691         if (ret < 0)
 692                 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
 693 out:
 694         up_read(&mkey->sem);
 695         key_put(mkey);
 696         return ret;
 697 }
 698
 699 static void __ekey_init(struct encrypted_key_payload *epayload,
 700                         const char *format, const char *master_desc,
 701                         const char *datalen)
 702 {
 703         unsigned int format_len;
 704
 705         format_len = (!format) ? strlen(key_format_default) : strlen(format);
 706         epayload->format = epayload->payload_data + epayload->payload_datalen;
 707         epayload->master_desc = epayload->format + format_len + 1;
 708         epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
 709         epayload->iv = epayload->datalen + strlen(datalen) + 1;
 710         epayload->encrypted_data = epayload->iv + ivsize + 1;
 711         epayload->decrypted_data = epayload->payload_data;
 712
 713         if (!format)
 714                 memcpy(epayload->format, key_format_default, format_len);
 715         else {
 716                 if (!strcmp(format, key_format_ecryptfs))
 717                         epayload->decrypted_data =
 718                                 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
 719
 720                 memcpy(epayload->format, format, format_len);
 721         }
 722
 723         memcpy(epayload->master_desc, master_desc, strlen(master_desc));
 724         memcpy(epayload->datalen, datalen, strlen(datalen));
 725 }
 726
 727 /*
 728  * encrypted_init - initialize an encrypted key
 729  *
 730  * For a new key, use a random number for both the iv and data
 731  * itself.  For an old key, decrypt the hex encoded data.
 732  */
 733 static int encrypted_init(struct encrypted_key_payload *epayload,
 734                           const char *key_desc, const char *format,
 735                           const char *master_desc, const char *datalen,
 736                           const char *hex_encoded_iv)
 737 {
 738         int ret = 0;
 739
 740         if (format && !strcmp(format, key_format_ecryptfs)) {
 741                 ret = valid_ecryptfs_desc(key_desc);
 742                 if (ret < 0)
 743                         return ret;
 744
 745                 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
 746                                        key_desc);
 747         }
 748
 749         __ekey_init(epayload, format, master_desc, datalen);
 750         if (!hex_encoded_iv) {
 751                 get_random_bytes(epayload->iv, ivsize);
 752
 753                 get_random_bytes(epayload->decrypted_data,
 754                                  epayload->decrypted_datalen);
 755         } else
 756                 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
 757         return ret;
 758 }
 759
 760 /*
 761  * encrypted_instantiate - instantiate an encrypted key
 762  *
 763  * Decrypt an existing encrypted datablob or create a new encrypted key
 764  * based on a kernel random number.
 765  *
 766  * On success, return 0. Otherwise return errno.
 767  */
 768 static int encrypted_instantiate(struct key *key, const void *data,
 769                                  size_t datalen)
 770 {
 771         struct encrypted_key_payload *epayload = NULL;
 772         char *datablob = NULL;
 773         const char *format = NULL;
 774         char *master_desc = NULL;
 775         char *decrypted_datalen = NULL;
 776         char *hex_encoded_iv = NULL;
 777         int ret;
 778
 779         if (datalen <= 0 || datalen > 32767 || !data)
 780                 return -EINVAL;
 781
 782         datablob = kmalloc(datalen + 1, GFP_KERNEL);
 783         if (!datablob)
 784                 return -ENOMEM;
 785         datablob[datalen] = 0;
 786         memcpy(datablob, data, datalen);
 787         ret = datablob_parse(datablob, &format, &master_desc,
 788                              &decrypted_datalen, &hex_encoded_iv);
 789         if (ret < 0)
 790                 goto out;
 791
 792         epayload = encrypted_key_alloc(key, format, master_desc,
 793                                        decrypted_datalen);
 794         if (IS_ERR(epayload)) {
 795                 ret = PTR_ERR(epayload);
 796                 goto out;
 797         }
 798         ret = encrypted_init(epayload, key->description, format, master_desc,
 799                              decrypted_datalen, hex_encoded_iv);
 800         if (ret < 0) {
 801                 kfree(epayload);
 802                 goto out;
 803         }
 804
 805         rcu_assign_pointer(key->payload.data, epayload);
 806 out:
 807         kfree(datablob);
 808         return ret;
 809 }
 810
 811 static void encrypted_rcu_free(struct rcu_head *rcu)
 812 {
 813         struct encrypted_key_payload *epayload;
 814
 815         epayload = container_of(rcu, struct encrypted_key_payload, rcu);
 816         memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
 817         kfree(epayload);
 818 }
 819
 820 /*
 821  * encrypted_update - update the master key description
 822  *
 823  * Change the master key description for an existing encrypted key.
 824  * The next read will return an encrypted datablob using the new
 825  * master key description.
 826  *
 827  * On success, return 0. Otherwise return errno.
 828  */
 829 static int encrypted_update(struct key *key, const void *data, size_t datalen)
 830 {
 831         struct encrypted_key_payload *epayload = key->payload.data;
 832         struct encrypted_key_payload *new_epayload;
 833         char *buf;
 834         char *new_master_desc = NULL;
 835         const char *format = NULL;
 836         int ret = 0;
 837
 838         if (datalen <= 0 || datalen > 32767 || !data)
 839                 return -EINVAL;
 840
 841         buf = kmalloc(datalen + 1, GFP_KERNEL);
 842         if (!buf)
 843                 return -ENOMEM;
 844
 845         buf[datalen] = 0;
 846         memcpy(buf, data, datalen);
 847         ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
 848         if (ret < 0)
 849                 goto out;
 850
 851         ret = valid_master_desc(new_master_desc, epayload->master_desc);
 852         if (ret < 0)
 853                 goto out;
 854
 855         new_epayload = encrypted_key_alloc(key, epayload->format,
 856                                            new_master_desc, epayload->datalen);
 857         if (IS_ERR(new_epayload)) {
 858                 ret = PTR_ERR(new_epayload);
 859                 goto out;
 860         }
 861
 862         __ekey_init(new_epayload, epayload->format, new_master_desc,
 863                     epayload->datalen);
 864
 865         memcpy(new_epayload->iv, epayload->iv, ivsize);
 866         memcpy(new_epayload->payload_data, epayload->payload_data,
 867                epayload->payload_datalen);
 868
 869         rcu_assign_pointer(key->payload.data, new_epayload);
 870         call_rcu(&epayload->rcu, encrypted_rcu_free);
 871 out:
 872         kfree(buf);
 873         return ret;
 874 }
 875
 876 /*
 877  * encrypted_read - format and copy the encrypted data to userspace
 878  *
 879  * The resulting datablob format is:
 880  * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
 881  *
 882  * On success, return to userspace the encrypted key datablob size.
 883  */
 884 static long encrypted_read(const struct key *key, char __user *buffer,
 885                            size_t buflen)
 886 {
 887         struct encrypted_key_payload *epayload;
 888         struct key *mkey;
 889         u8 *master_key;
 890         size_t master_keylen;
 891         char derived_key[HASH_SIZE];
 892         char *ascii_buf;
 893         size_t asciiblob_len;
 894         int ret;
 895
 896         epayload = rcu_dereference_key(key);
 897
 898         /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
 899         asciiblob_len = epayload->datablob_len + ivsize + 1
 900             + roundup(epayload->decrypted_datalen, blksize)
 901             + (HASH_SIZE * 2);
 902
 903         if (!buffer || buflen < asciiblob_len)
 904                 return asciiblob_len;
 905
 906         mkey = request_master_key(epayload, &master_key, &master_keylen);
 907         if (IS_ERR(mkey))
 908                 return PTR_ERR(mkey);
 909
 910         ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
 911         if (ret < 0)
 912                 goto out;
 913
 914         ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
 915         if (ret < 0)
 916                 goto out;
 917
 918         ret = datablob_hmac_append(epayload, master_key, master_keylen);
 919         if (ret < 0)
 920                 goto out;
 921
 922         ascii_buf = datablob_format(epayload, asciiblob_len);
 923         if (!ascii_buf) {
 924                 ret = -ENOMEM;
 925                 goto out;
 926         }
 927
 928         up_read(&mkey->sem);
 929         key_put(mkey);
 930
 931         if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
 932                 ret = -EFAULT;
 933         kfree(ascii_buf);
 934
 935         return asciiblob_len;
 936 out:
 937         up_read(&mkey->sem);
 938         key_put(mkey);
 939         return ret;
 940 }
 941
 942 /*
 943  * encrypted_destroy - before freeing the key, clear the decrypted data
 944  *
 945  * Before freeing the key, clear the memory containing the decrypted
 946  * key data.
 947  */
 948 static void encrypted_destroy(struct key *key)
 949 {
 950         struct encrypted_key_payload *epayload = key->payload.data;
 951
 952         if (!epayload)
 953                 return;
 954
 955         memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
 956         kfree(key->payload.data);
 957 }
 958
 959 struct key_type key_type_encrypted = {
 960         .name = "encrypted",
 961         .instantiate = encrypted_instantiate,
 962         .update = encrypted_update,
 963         .match = user_match,
 964         .destroy = encrypted_destroy,
 965         .describe = user_describe,
 966         .read = encrypted_read,
 967 };
 968 EXPORT_SYMBOL_GPL(key_type_encrypted);
 969
 970 static void encrypted_shash_release(void)
 971 {
 972         if (hashalg)
 973                 crypto_free_shash(hashalg);
 974         if (hmacalg)
 975                 crypto_free_shash(hmacalg);
 976 }
 977
 978 static int __init encrypted_shash_alloc(void)
 979 {
 980         int ret;
 981
 982         hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
 983         if (IS_ERR(hmacalg)) {
 984                 pr_info("encrypted_key: could not allocate crypto %s\n",
 985                         hmac_alg);
 986                 return PTR_ERR(hmacalg);
 987         }
 988
 989         hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
 990         if (IS_ERR(hashalg)) {
 991                 pr_info("encrypted_key: could not allocate crypto %s\n",
 992                         hash_alg);
 993                 ret = PTR_ERR(hashalg);
 994                 goto hashalg_fail;
 995         }
 996
 997         return 0;
 998
 999 hashalg_fail:
1000         crypto_free_shash(hmacalg);
1001         return ret;
1002 }
1003
1004 static int __init init_encrypted(void)
1005 {
1006         int ret;
1007
1008         ret = encrypted_shash_alloc();
1009         if (ret < 0)
1010                 return ret;
1011         ret = register_key_type(&key_type_encrypted);
1012         if (ret < 0)
1013                 goto out;
1014         return aes_get_sizes();
1015 out:
1016         encrypted_shash_release();
1017         return ret;
1018
1019 }
1020
1021 static void __exit cleanup_encrypted(void)
1022 {
1023         encrypted_shash_release();
1024         unregister_key_type(&key_type_encrypted);
1025 }
1026
1027 late_initcall(init_encrypted);
1028 module_exit(cleanup_encrypted);
1029
1030 MODULE_LICENSE("GPL");