crypto/drbg.c

   1 /*
   2  * DRBG: Deterministic Random Bits Generator
   3  *       Based on NIST Recommended DRBG from NIST SP800-90A with the following
   4  *       properties:
   5  *              * CTR DRBG with DF with AES-128, AES-192, AES-256 cores
   6  *              * Hash DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
   7  *              * HMAC DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
   8  *              * with and without prediction resistance
   9  *
  10  * Copyright Stephan Mueller <smueller@chronox.de>, 2014
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, and the entire permission notice in its entirety,
  17  *    including the disclaimer of warranties.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. The name of the author may not be used to endorse or promote
  22  *    products derived from this software without specific prior
  23  *    written permission.
  24  *
  25  * ALTERNATIVELY, this product may be distributed under the terms of
  26  * the GNU General Public License, in which case the provisions of the GPL are
  27  * required INSTEAD OF the above restrictions.  (This clause is
  28  * necessary due to a potential bad interaction between the GPL and
  29  * the restrictions contained in a BSD-style copyright.)
  30  *
  31  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  32  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
  34  * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
  35  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  36  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  37  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  38  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  39  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  40  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
  41  * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
  42  * DAMAGE.
  43  *
  44  * DRBG Usage
  45  * ==========
  46  * The SP 800-90A DRBG allows the user to specify a personalization string
  47  * for initialization as well as an additional information string for each
  48  * random number request. The following code fragments show how a caller
  49  * uses the kernel crypto API to use the full functionality of the DRBG.
  50  *
  51  * Usage without any additional data
  52  * ---------------------------------
  53  * struct crypto_rng *drng;
  54  * int err;
  55  * char data[DATALEN];
  56  *
  57  * drng = crypto_alloc_rng(drng_name, 0, 0);
  58  * err = crypto_rng_get_bytes(drng, &data, DATALEN);
  59  * crypto_free_rng(drng);
  60  *
  61  *
  62  * Usage with personalization string during initialization
  63  * -------------------------------------------------------
  64  * struct crypto_rng *drng;
  65  * int err;
  66  * char data[DATALEN];
  67  * struct drbg_string pers;
  68  * char personalization[11] = "some-string";
  69  *
  70  * drbg_string_fill(&pers, personalization, strlen(personalization));
  71  * drng = crypto_alloc_rng(drng_name, 0, 0);
  72  * // The reset completely re-initializes the DRBG with the provided
  73  * // personalization string
  74  * err = crypto_rng_reset(drng, &personalization, strlen(personalization));
  75  * err = crypto_rng_get_bytes(drng, &data, DATALEN);
  76  * crypto_free_rng(drng);
  77  *
  78  *
  79  * Usage with additional information string during random number request
  80  * ---------------------------------------------------------------------
  81  * struct crypto_rng *drng;
  82  * int err;
  83  * char data[DATALEN];
  84  * char addtl_string[11] = "some-string";
  85  * string drbg_string addtl;
  86  *
  87  * drbg_string_fill(&addtl, addtl_string, strlen(addtl_string));
  88  * drng = crypto_alloc_rng(drng_name, 0, 0);
  89  * // The following call is a wrapper to crypto_rng_get_bytes() and returns
  90  * // the same error codes.
  91  * err = crypto_drbg_get_bytes_addtl(drng, &data, DATALEN, &addtl);
  92  * crypto_free_rng(drng);
  93  *
  94  *
  95  * Usage with personalization and additional information strings
  96  * -------------------------------------------------------------
  97  * Just mix both scenarios above.
  98  */
  99
 100 #include <crypto/drbg.h>
 101 #include <linux/kernel.h>
 102
 103 /***************************************************************
 104  * Backend cipher definitions available to DRBG
 105  ***************************************************************/
 106
 107 /*
 108  * The order of the DRBG definitions here matter: every DRBG is registered
 109  * as stdrng. Each DRBG receives an increasing cra_priority values the later
 110  * they are defined in this array (see drbg_fill_array).
 111  *
 112  * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
 113  * the SHA256 / AES 256 over other ciphers. Thus, the favored
 114  * DRBGs are the latest entries in this array.
 115  */
 116 static const struct drbg_core drbg_cores[] = {
 117 #ifdef CONFIG_CRYPTO_DRBG_CTR
 118         {
 119                 .flags = DRBG_CTR | DRBG_STRENGTH128,
 120                 .statelen = 32, /* 256 bits as defined in 10.2.1 */
 121                 .blocklen_bytes = 16,
 122                 .cra_name = "ctr_aes128",
 123                 .backend_cra_name = "aes",
 124         }, {
 125                 .flags = DRBG_CTR | DRBG_STRENGTH192,
 126                 .statelen = 40, /* 320 bits as defined in 10.2.1 */
 127                 .blocklen_bytes = 16,
 128                 .cra_name = "ctr_aes192",
 129                 .backend_cra_name = "aes",
 130         }, {
 131                 .flags = DRBG_CTR | DRBG_STRENGTH256,
 132                 .statelen = 48, /* 384 bits as defined in 10.2.1 */
 133                 .blocklen_bytes = 16,
 134                 .cra_name = "ctr_aes256",
 135                 .backend_cra_name = "aes",
 136         },
 137 #endif /* CONFIG_CRYPTO_DRBG_CTR */
 138 #ifdef CONFIG_CRYPTO_DRBG_HASH
 139         {
 140                 .flags = DRBG_HASH | DRBG_STRENGTH128,
 141                 .statelen = 55, /* 440 bits */
 142                 .blocklen_bytes = 20,
 143                 .cra_name = "sha1",
 144                 .backend_cra_name = "sha1",
 145         }, {
 146                 .flags = DRBG_HASH | DRBG_STRENGTH256,
 147                 .statelen = 111, /* 888 bits */
 148                 .blocklen_bytes = 48,
 149                 .cra_name = "sha384",
 150                 .backend_cra_name = "sha384",
 151         }, {
 152                 .flags = DRBG_HASH | DRBG_STRENGTH256,
 153                 .statelen = 111, /* 888 bits */
 154                 .blocklen_bytes = 64,
 155                 .cra_name = "sha512",
 156                 .backend_cra_name = "sha512",
 157         }, {
 158                 .flags = DRBG_HASH | DRBG_STRENGTH256,
 159                 .statelen = 55, /* 440 bits */
 160                 .blocklen_bytes = 32,
 161                 .cra_name = "sha256",
 162                 .backend_cra_name = "sha256",
 163         },
 164 #endif /* CONFIG_CRYPTO_DRBG_HASH */
 165 #ifdef CONFIG_CRYPTO_DRBG_HMAC
 166         {
 167                 .flags = DRBG_HMAC | DRBG_STRENGTH128,
 168                 .statelen = 20, /* block length of cipher */
 169                 .blocklen_bytes = 20,
 170                 .cra_name = "hmac_sha1",
 171                 .backend_cra_name = "hmac(sha1)",
 172         }, {
 173                 .flags = DRBG_HMAC | DRBG_STRENGTH256,
 174                 .statelen = 48, /* block length of cipher */
 175                 .blocklen_bytes = 48,
 176                 .cra_name = "hmac_sha384",
 177                 .backend_cra_name = "hmac(sha384)",
 178         }, {
 179                 .flags = DRBG_HMAC | DRBG_STRENGTH256,
 180                 .statelen = 64, /* block length of cipher */
 181                 .blocklen_bytes = 64,
 182                 .cra_name = "hmac_sha512",
 183                 .backend_cra_name = "hmac(sha512)",
 184         }, {
 185                 .flags = DRBG_HMAC | DRBG_STRENGTH256,
 186                 .statelen = 32, /* block length of cipher */
 187                 .blocklen_bytes = 32,
 188                 .cra_name = "hmac_sha256",
 189                 .backend_cra_name = "hmac(sha256)",
 190         },
 191 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
 192 };
 193
 194 static int drbg_uninstantiate(struct drbg_state *drbg);
 195
 196 /******************************************************************
 197  * Generic helper functions
 198  ******************************************************************/
 199
 200 /*
 201  * Return strength of DRBG according to SP800-90A section 8.4
 202  *
 203  * @flags DRBG flags reference
 204  *
 205  * Return: normalized strength in *bytes* value or 32 as default
 206  *         to counter programming errors
 207  */
 208 static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
 209 {
 210         switch (flags & DRBG_STRENGTH_MASK) {
 211         case DRBG_STRENGTH128:
 212                 return 16;
 213         case DRBG_STRENGTH192:
 214                 return 24;
 215         case DRBG_STRENGTH256:
 216                 return 32;
 217         default:
 218                 return 32;
 219         }
 220 }
 221
 222 /*
 223  * Convert an integer into a byte representation of this integer.
 224  * The byte representation is big-endian
 225  *
 226  * @val value to be converted
 227  * @buf buffer holding the converted integer -- caller must ensure that
 228  *      buffer size is at least 32 bit
 229  */
 230 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
 231 static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
 232 {
 233         struct s {
 234                 __be32 conv;
 235         };
 236         struct s *conversion = (struct s *) buf;
 237
 238         conversion->conv = cpu_to_be32(val);
 239 }
 240 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
 241
 242 /******************************************************************
 243  * CTR DRBG callback functions
 244  ******************************************************************/
 245
 246 #ifdef CONFIG_CRYPTO_DRBG_CTR
 247 #define CRYPTO_DRBG_CTR_STRING "CTR "
 248 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
 249 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
 250 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
 251 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
 252 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
 253 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");
 254
 255 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
 256                                  const unsigned char *key);
 257 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
 258                           const struct drbg_string *in);
 259 static int drbg_init_sym_kernel(struct drbg_state *drbg);
 260 static int drbg_fini_sym_kernel(struct drbg_state *drbg);
 261 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
 262                               u8 *inbuf, u32 inbuflen,
 263                               u8 *outbuf, u32 outlen);
 264 #define DRBG_CTR_NULL_LEN 128
 265
 266 /* BCC function for CTR DRBG as defined in 10.4.3 */
 267 static int drbg_ctr_bcc(struct drbg_state *drbg,
 268                         unsigned char *out, const unsigned char *key,
 269                         struct list_head *in)
 270 {
 271         int ret = 0;
 272         struct drbg_string *curr = NULL;
 273         struct drbg_string data;
 274         short cnt = 0;
 275
 276         drbg_string_fill(&data, out, drbg_blocklen(drbg));
 277
 278         /* 10.4.3 step 2 / 4 */
 279         drbg_kcapi_symsetkey(drbg, key);
 280         list_for_each_entry(curr, in, list) {
 281                 const unsigned char *pos = curr->buf;
 282                 size_t len = curr->len;
 283                 /* 10.4.3 step 4.1 */
 284                 while (len) {
 285                         /* 10.4.3 step 4.2 */
 286                         if (drbg_blocklen(drbg) == cnt) {
 287                                 cnt = 0;
 288                                 ret = drbg_kcapi_sym(drbg, out, &data);
 289                                 if (ret)
 290                                         return ret;
 291                         }
 292                         out[cnt] ^= *pos;
 293                         pos++;
 294                         cnt++;
 295                         len--;
 296                 }
 297         }
 298         /* 10.4.3 step 4.2 for last block */
 299         if (cnt)
 300                 ret = drbg_kcapi_sym(drbg, out, &data);
 301
 302         return ret;
 303 }
 304
 305 /*
 306  * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
 307  * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
 308  * the scratchpad is used as follows:
 309  * drbg_ctr_update:
 310  *      temp
 311  *              start: drbg->scratchpad
 312  *              length: drbg_statelen(drbg) + drbg_blocklen(drbg)
 313  *                      note: the cipher writing into this variable works
 314  *                      blocklen-wise. Now, when the statelen is not a multiple
 315  *                      of blocklen, the generateion loop below "spills over"
 316  *                      by at most blocklen. Thus, we need to give sufficient
 317  *                      memory.
 318  *      df_data
 319  *              start: drbg->scratchpad +
 320  *                              drbg_statelen(drbg) + drbg_blocklen(drbg)
 321  *              length: drbg_statelen(drbg)
 322  *
 323  * drbg_ctr_df:
 324  *      pad
 325  *              start: df_data + drbg_statelen(drbg)
 326  *              length: drbg_blocklen(drbg)
 327  *      iv
 328  *              start: pad + drbg_blocklen(drbg)
 329  *              length: drbg_blocklen(drbg)
 330  *      temp
 331  *              start: iv + drbg_blocklen(drbg)
 332  *              length: drbg_satelen(drbg) + drbg_blocklen(drbg)
 333  *                      note: temp is the buffer that the BCC function operates
 334  *                      on. BCC operates blockwise. drbg_statelen(drbg)
 335  *                      is sufficient when the DRBG state length is a multiple
 336  *                      of the block size. For AES192 (and maybe other ciphers)
 337  *                      this is not correct and the length for temp is
 338  *                      insufficient (yes, that also means for such ciphers,
 339  *                      the final output of all BCC rounds are truncated).
 340  *                      Therefore, add drbg_blocklen(drbg) to cover all
 341  *                      possibilities.
 342  */
 343
 344 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
 345 static int drbg_ctr_df(struct drbg_state *drbg,
 346                        unsigned char *df_data, size_t bytes_to_return,
 347                        struct list_head *seedlist)
 348 {
 349         int ret = -EFAULT;
 350         unsigned char L_N[8];
 351         /* S3 is input */
 352         struct drbg_string S1, S2, S4, cipherin;
 353         LIST_HEAD(bcc_list);
 354         unsigned char *pad = df_data + drbg_statelen(drbg);
 355         unsigned char *iv = pad + drbg_blocklen(drbg);
 356         unsigned char *temp = iv + drbg_blocklen(drbg);
 357         size_t padlen = 0;
 358         unsigned int templen = 0;
 359         /* 10.4.2 step 7 */
 360         unsigned int i = 0;
 361         /* 10.4.2 step 8 */
 362         const unsigned char *K = (unsigned char *)
 363                            "\x00\x01\x02\x03\x04\x05\x06\x07"
 364                            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
 365                            "\x10\x11\x12\x13\x14\x15\x16\x17"
 366                            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
 367         unsigned char *X;
 368         size_t generated_len = 0;
 369         size_t inputlen = 0;
 370         struct drbg_string *seed = NULL;
 371
 372         memset(pad, 0, drbg_blocklen(drbg));
 373         memset(iv, 0, drbg_blocklen(drbg));
 374
 375         /* 10.4.2 step 1 is implicit as we work byte-wise */
 376
 377         /* 10.4.2 step 2 */
 378         if ((512/8) < bytes_to_return)
 379                 return -EINVAL;
 380
 381         /* 10.4.2 step 2 -- calculate the entire length of all input data */
 382         list_for_each_entry(seed, seedlist, list)
 383                 inputlen += seed->len;
 384         drbg_cpu_to_be32(inputlen, &L_N[0]);
 385
 386         /* 10.4.2 step 3 */
 387         drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
 388
 389         /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
 390         padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
 391         /* wrap the padlen appropriately */
 392         if (padlen)
 393                 padlen = drbg_blocklen(drbg) - padlen;
 394         /*
 395          * pad / padlen contains the 0x80 byte and the following zero bytes.
 396          * As the calculated padlen value only covers the number of zero
 397          * bytes, this value has to be incremented by one for the 0x80 byte.
 398          */
 399         padlen++;
 400         pad[0] = 0x80;
 401
 402         /* 10.4.2 step 4 -- first fill the linked list and then order it */
 403         drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
 404         list_add_tail(&S1.list, &bcc_list);
 405         drbg_string_fill(&S2, L_N, sizeof(L_N));
 406         list_add_tail(&S2.list, &bcc_list);
 407         list_splice_tail(seedlist, &bcc_list);
 408         drbg_string_fill(&S4, pad, padlen);
 409         list_add_tail(&S4.list, &bcc_list);
 410
 411         /* 10.4.2 step 9 */
 412         while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
 413                 /*
 414                  * 10.4.2 step 9.1 - the padding is implicit as the buffer
 415                  * holds zeros after allocation -- even the increment of i
 416                  * is irrelevant as the increment remains within length of i
 417                  */
 418                 drbg_cpu_to_be32(i, iv);
 419                 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
 420                 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
 421                 if (ret)
 422                         goto out;
 423                 /* 10.4.2 step 9.3 */
 424                 i++;
 425                 templen += drbg_blocklen(drbg);
 426         }
 427
 428         /* 10.4.2 step 11 */
 429         X = temp + (drbg_keylen(drbg));
 430         drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
 431
 432         /* 10.4.2 step 12: overwriting of outval is implemented in next step */
 433
 434         /* 10.4.2 step 13 */
 435         drbg_kcapi_symsetkey(drbg, temp);
 436         while (generated_len < bytes_to_return) {
 437                 short blocklen = 0;
 438                 /*
 439                  * 10.4.2 step 13.1: the truncation of the key length is
 440                  * implicit as the key is only drbg_blocklen in size based on
 441                  * the implementation of the cipher function callback
 442                  */
 443                 ret = drbg_kcapi_sym(drbg, X, &cipherin);
 444                 if (ret)
 445                         goto out;
 446                 blocklen = (drbg_blocklen(drbg) <
 447                                 (bytes_to_return - generated_len)) ?
 448                             drbg_blocklen(drbg) :
 449                                 (bytes_to_return - generated_len);
 450                 /* 10.4.2 step 13.2 and 14 */
 451                 memcpy(df_data + generated_len, X, blocklen);
 452                 generated_len += blocklen;
 453         }
 454
 455         ret = 0;
 456
 457 out:
 458         memset(iv, 0, drbg_blocklen(drbg));
 459         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 460         memset(pad, 0, drbg_blocklen(drbg));
 461         return ret;
 462 }
 463
 464 /*
 465  * update function of CTR DRBG as defined in 10.2.1.2
 466  *
 467  * The reseed variable has an enhanced meaning compared to the update
 468  * functions of the other DRBGs as follows:
 469  * 0 => initial seed from initialization
 470  * 1 => reseed via drbg_seed
 471  * 2 => first invocation from drbg_ctr_update when addtl is present. In
 472  *      this case, the df_data scratchpad is not deleted so that it is
 473  *      available for another calls to prevent calling the DF function
 474  *      again.
 475  * 3 => second invocation from drbg_ctr_update. When the update function
 476  *      was called with addtl, the df_data memory already contains the
 477  *      DFed addtl information and we do not need to call DF again.
 478  */
 479 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
 480                            int reseed)
 481 {
 482         int ret = -EFAULT;
 483         /* 10.2.1.2 step 1 */
 484         unsigned char *temp = drbg->scratchpad;
 485         unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
 486                                  drbg_blocklen(drbg);
 487
 488         if (3 > reseed)
 489                 memset(df_data, 0, drbg_statelen(drbg));
 490
 491         if (!reseed) {
 492                 /*
 493                  * The DRBG uses the CTR mode of the underlying AES cipher. The
 494                  * CTR mode increments the counter value after the AES operation
 495                  * but SP800-90A requires that the counter is incremented before
 496                  * the AES operation. Hence, we increment it at the time we set
 497                  * it by one.
 498                  */
 499                 crypto_inc(drbg->V, drbg_blocklen(drbg));
 500
 501                 ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
 502                                              drbg_keylen(drbg));
 503                 if (ret)
 504                         goto out;
 505         }
 506
 507         /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
 508         if (seed) {
 509                 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
 510                 if (ret)
 511                         goto out;
 512         }
 513
 514         ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
 515                                  temp, drbg_statelen(drbg));
 516         if (ret)
 517                 return ret;
 518
 519         /* 10.2.1.2 step 5 */
 520         ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
 521                                      drbg_keylen(drbg));
 522         if (ret)
 523                 goto out;
 524         /* 10.2.1.2 step 6 */
 525         memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
 526         /* See above: increment counter by one to compensate timing of CTR op */
 527         crypto_inc(drbg->V, drbg_blocklen(drbg));
 528         ret = 0;
 529
 530 out:
 531         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 532         if (2 != reseed)
 533                 memset(df_data, 0, drbg_statelen(drbg));
 534         return ret;
 535 }
 536
 537 /*
 538  * scratchpad use: drbg_ctr_update is called independently from
 539  * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
 540  */
 541 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
 542 static int drbg_ctr_generate(struct drbg_state *drbg,
 543                              unsigned char *buf, unsigned int buflen,
 544                              struct list_head *addtl)
 545 {
 546         int ret;
 547         int len = min_t(int, buflen, INT_MAX);
 548
 549         /* 10.2.1.5.2 step 2 */
 550         if (addtl && !list_empty(addtl)) {
 551                 ret = drbg_ctr_update(drbg, addtl, 2);
 552                 if (ret)
 553                         return 0;
 554         }
 555
 556         /* 10.2.1.5.2 step 4.1 */
 557         ret = drbg_kcapi_sym_ctr(drbg, drbg->ctr_null_value, DRBG_CTR_NULL_LEN,
 558                                  buf, len);
 559         if (ret)
 560                 return ret;
 561
 562         /* 10.2.1.5.2 step 6 */
 563         ret = drbg_ctr_update(drbg, NULL, 3);
 564         if (ret)
 565                 len = ret;
 566
 567         return len;
 568 }
 569
 570 static const struct drbg_state_ops drbg_ctr_ops = {
 571         .update         = drbg_ctr_update,
 572         .generate       = drbg_ctr_generate,
 573         .crypto_init    = drbg_init_sym_kernel,
 574         .crypto_fini    = drbg_fini_sym_kernel,
 575 };
 576 #endif /* CONFIG_CRYPTO_DRBG_CTR */
 577
 578 /******************************************************************
 579  * HMAC DRBG callback functions
 580  ******************************************************************/
 581
 582 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
 583 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
 584                            const struct list_head *in);
 585 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
 586                                   const unsigned char *key);
 587 static int drbg_init_hash_kernel(struct drbg_state *drbg);
 588 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
 589 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
 590
 591 #ifdef CONFIG_CRYPTO_DRBG_HMAC
 592 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
 593 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
 594 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
 595 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
 596 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
 597 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
 598 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
 599 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
 600 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
 601
 602 /* update function of HMAC DRBG as defined in 10.1.2.2 */
 603 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
 604                             int reseed)
 605 {
 606         int ret = -EFAULT;
 607         int i = 0;
 608         struct drbg_string seed1, seed2, vdata;
 609         LIST_HEAD(seedlist);
 610         LIST_HEAD(vdatalist);
 611
 612         if (!reseed) {
 613                 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
 614                 memset(drbg->V, 1, drbg_statelen(drbg));
 615                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
 616         }
 617
 618         drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
 619         list_add_tail(&seed1.list, &seedlist);
 620         /* buffer of seed2 will be filled in for loop below with one byte */
 621         drbg_string_fill(&seed2, NULL, 1);
 622         list_add_tail(&seed2.list, &seedlist);
 623         /* input data of seed is allowed to be NULL at this point */
 624         if (seed)
 625                 list_splice_tail(seed, &seedlist);
 626
 627         drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
 628         list_add_tail(&vdata.list, &vdatalist);
 629         for (i = 2; 0 < i; i--) {
 630                 /* first round uses 0x0, second 0x1 */
 631                 unsigned char prefix = DRBG_PREFIX0;
 632                 if (1 == i)
 633                         prefix = DRBG_PREFIX1;
 634                 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
 635                 seed2.buf = &prefix;
 636                 ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
 637                 if (ret)
 638                         return ret;
 639                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
 640
 641                 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
 642                 ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
 643                 if (ret)
 644                         return ret;
 645
 646                 /* 10.1.2.2 step 3 */
 647                 if (!seed)
 648                         return ret;
 649         }
 650
 651         return 0;
 652 }
 653
 654 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
 655 static int drbg_hmac_generate(struct drbg_state *drbg,
 656                               unsigned char *buf,
 657                               unsigned int buflen,
 658                               struct list_head *addtl)
 659 {
 660         int len = 0;
 661         int ret = 0;
 662         struct drbg_string data;
 663         LIST_HEAD(datalist);
 664
 665         /* 10.1.2.5 step 2 */
 666         if (addtl && !list_empty(addtl)) {
 667                 ret = drbg_hmac_update(drbg, addtl, 1);
 668                 if (ret)
 669                         return ret;
 670         }
 671
 672         drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
 673         list_add_tail(&data.list, &datalist);
 674         while (len < buflen) {
 675                 unsigned int outlen = 0;
 676                 /* 10.1.2.5 step 4.1 */
 677                 ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
 678                 if (ret)
 679                         return ret;
 680                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 681                           drbg_blocklen(drbg) : (buflen - len);
 682
 683                 /* 10.1.2.5 step 4.2 */
 684                 memcpy(buf + len, drbg->V, outlen);
 685                 len += outlen;
 686         }
 687
 688         /* 10.1.2.5 step 6 */
 689         if (addtl && !list_empty(addtl))
 690                 ret = drbg_hmac_update(drbg, addtl, 1);
 691         else
 692                 ret = drbg_hmac_update(drbg, NULL, 1);
 693         if (ret)
 694                 return ret;
 695
 696         return len;
 697 }
 698
 699 static const struct drbg_state_ops drbg_hmac_ops = {
 700         .update         = drbg_hmac_update,
 701         .generate       = drbg_hmac_generate,
 702         .crypto_init    = drbg_init_hash_kernel,
 703         .crypto_fini    = drbg_fini_hash_kernel,
 704 };
 705 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
 706
 707 /******************************************************************
 708  * Hash DRBG callback functions
 709  ******************************************************************/
 710
 711 #ifdef CONFIG_CRYPTO_DRBG_HASH
 712 #define CRYPTO_DRBG_HASH_STRING "HASH "
 713 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
 714 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
 715 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
 716 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
 717 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
 718 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
 719 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
 720 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
 721
 722 /*
 723  * Increment buffer
 724  *
 725  * @dst buffer to increment
 726  * @add value to add
 727  */
 728 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
 729                                 const unsigned char *add, size_t addlen)
 730 {
 731         /* implied: dstlen > addlen */
 732         unsigned char *dstptr;
 733         const unsigned char *addptr;
 734         unsigned int remainder = 0;
 735         size_t len = addlen;
 736
 737         dstptr = dst + (dstlen-1);
 738         addptr = add + (addlen-1);
 739         while (len) {
 740                 remainder += *dstptr + *addptr;
 741                 *dstptr = remainder & 0xff;
 742                 remainder >>= 8;
 743                 len--; dstptr--; addptr--;
 744         }
 745         len = dstlen - addlen;
 746         while (len && remainder > 0) {
 747                 remainder = *dstptr + 1;
 748                 *dstptr = remainder & 0xff;
 749                 remainder >>= 8;
 750                 len--; dstptr--;
 751         }
 752 }
 753
 754 /*
 755  * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
 756  * interlinked, the scratchpad is used as follows:
 757  * drbg_hash_update
 758  *      start: drbg->scratchpad
 759  *      length: drbg_statelen(drbg)
 760  * drbg_hash_df:
 761  *      start: drbg->scratchpad + drbg_statelen(drbg)
 762  *      length: drbg_blocklen(drbg)
 763  *
 764  * drbg_hash_process_addtl uses the scratchpad, but fully completes
 765  * before either of the functions mentioned before are invoked. Therefore,
 766  * drbg_hash_process_addtl does not need to be specifically considered.
 767  */
 768
 769 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
 770 static int drbg_hash_df(struct drbg_state *drbg,
 771                         unsigned char *outval, size_t outlen,
 772                         struct list_head *entropylist)
 773 {
 774         int ret = 0;
 775         size_t len = 0;
 776         unsigned char input[5];
 777         unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
 778         struct drbg_string data;
 779
 780         /* 10.4.1 step 3 */
 781         input[0] = 1;
 782         drbg_cpu_to_be32((outlen * 8), &input[1]);
 783
 784         /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
 785         drbg_string_fill(&data, input, 5);
 786         list_add(&data.list, entropylist);
 787
 788         /* 10.4.1 step 4 */
 789         while (len < outlen) {
 790                 short blocklen = 0;
 791                 /* 10.4.1 step 4.1 */
 792                 ret = drbg_kcapi_hash(drbg, tmp, entropylist);
 793                 if (ret)
 794                         goto out;
 795                 /* 10.4.1 step 4.2 */
 796                 input[0]++;
 797                 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
 798                             drbg_blocklen(drbg) : (outlen - len);
 799                 memcpy(outval + len, tmp, blocklen);
 800                 len += blocklen;
 801         }
 802
 803 out:
 804         memset(tmp, 0, drbg_blocklen(drbg));
 805         return ret;
 806 }
 807
 808 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
 809 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
 810                             int reseed)
 811 {
 812         int ret = 0;
 813         struct drbg_string data1, data2;
 814         LIST_HEAD(datalist);
 815         LIST_HEAD(datalist2);
 816         unsigned char *V = drbg->scratchpad;
 817         unsigned char prefix = DRBG_PREFIX1;
 818
 819         if (!seed)
 820                 return -EINVAL;
 821
 822         if (reseed) {
 823                 /* 10.1.1.3 step 1 */
 824                 memcpy(V, drbg->V, drbg_statelen(drbg));
 825                 drbg_string_fill(&data1, &prefix, 1);
 826                 list_add_tail(&data1.list, &datalist);
 827                 drbg_string_fill(&data2, V, drbg_statelen(drbg));
 828                 list_add_tail(&data2.list, &datalist);
 829         }
 830         list_splice_tail(seed, &datalist);
 831
 832         /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
 833         ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
 834         if (ret)
 835                 goto out;
 836
 837         /* 10.1.1.2 / 10.1.1.3 step 4  */
 838         prefix = DRBG_PREFIX0;
 839         drbg_string_fill(&data1, &prefix, 1);
 840         list_add_tail(&data1.list, &datalist2);
 841         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 842         list_add_tail(&data2.list, &datalist2);
 843         /* 10.1.1.2 / 10.1.1.3 step 4 */
 844         ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
 845
 846 out:
 847         memset(drbg->scratchpad, 0, drbg_statelen(drbg));
 848         return ret;
 849 }
 850
 851 /* processing of additional information string for Hash DRBG */
 852 static int drbg_hash_process_addtl(struct drbg_state *drbg,
 853                                    struct list_head *addtl)
 854 {
 855         int ret = 0;
 856         struct drbg_string data1, data2;
 857         LIST_HEAD(datalist);
 858         unsigned char prefix = DRBG_PREFIX2;
 859
 860         /* 10.1.1.4 step 2 */
 861         if (!addtl || list_empty(addtl))
 862                 return 0;
 863
 864         /* 10.1.1.4 step 2a */
 865         drbg_string_fill(&data1, &prefix, 1);
 866         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 867         list_add_tail(&data1.list, &datalist);
 868         list_add_tail(&data2.list, &datalist);
 869         list_splice_tail(addtl, &datalist);
 870         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
 871         if (ret)
 872                 goto out;
 873
 874         /* 10.1.1.4 step 2b */
 875         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 876                      drbg->scratchpad, drbg_blocklen(drbg));
 877
 878 out:
 879         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 880         return ret;
 881 }
 882
 883 /* Hashgen defined in 10.1.1.4 */
 884 static int drbg_hash_hashgen(struct drbg_state *drbg,
 885                              unsigned char *buf,
 886                              unsigned int buflen)
 887 {
 888         int len = 0;
 889         int ret = 0;
 890         unsigned char *src = drbg->scratchpad;
 891         unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
 892         struct drbg_string data;
 893         LIST_HEAD(datalist);
 894
 895         /* 10.1.1.4 step hashgen 2 */
 896         memcpy(src, drbg->V, drbg_statelen(drbg));
 897
 898         drbg_string_fill(&data, src, drbg_statelen(drbg));
 899         list_add_tail(&data.list, &datalist);
 900         while (len < buflen) {
 901                 unsigned int outlen = 0;
 902                 /* 10.1.1.4 step hashgen 4.1 */
 903                 ret = drbg_kcapi_hash(drbg, dst, &datalist);
 904                 if (ret) {
 905                         len = ret;
 906                         goto out;
 907                 }
 908                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 909                           drbg_blocklen(drbg) : (buflen - len);
 910                 /* 10.1.1.4 step hashgen 4.2 */
 911                 memcpy(buf + len, dst, outlen);
 912                 len += outlen;
 913                 /* 10.1.1.4 hashgen step 4.3 */
 914                 if (len < buflen)
 915                         crypto_inc(src, drbg_statelen(drbg));
 916         }
 917
 918 out:
 919         memset(drbg->scratchpad, 0,
 920                (drbg_statelen(drbg) + drbg_blocklen(drbg)));
 921         return len;
 922 }
 923
 924 /* generate function for Hash DRBG as defined in  10.1.1.4 */
 925 static int drbg_hash_generate(struct drbg_state *drbg,
 926                               unsigned char *buf, unsigned int buflen,
 927                               struct list_head *addtl)
 928 {
 929         int len = 0;
 930         int ret = 0;
 931         union {
 932                 unsigned char req[8];
 933                 __be64 req_int;
 934         } u;
 935         unsigned char prefix = DRBG_PREFIX3;
 936         struct drbg_string data1, data2;
 937         LIST_HEAD(datalist);
 938
 939         /* 10.1.1.4 step 2 */
 940         ret = drbg_hash_process_addtl(drbg, addtl);
 941         if (ret)
 942                 return ret;
 943         /* 10.1.1.4 step 3 */
 944         len = drbg_hash_hashgen(drbg, buf, buflen);
 945
 946         /* this is the value H as documented in 10.1.1.4 */
 947         /* 10.1.1.4 step 4 */
 948         drbg_string_fill(&data1, &prefix, 1);
 949         list_add_tail(&data1.list, &datalist);
 950         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 951         list_add_tail(&data2.list, &datalist);
 952         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
 953         if (ret) {
 954                 len = ret;
 955                 goto out;
 956         }
 957
 958         /* 10.1.1.4 step 5 */
 959         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 960                      drbg->scratchpad, drbg_blocklen(drbg));
 961         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 962                      drbg->C, drbg_statelen(drbg));
 963         u.req_int = cpu_to_be64(drbg->reseed_ctr);
 964         drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
 965
 966 out:
 967         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 968         return len;
 969 }
 970
 971 /*
 972  * scratchpad usage: as update and generate are used isolated, both
 973  * can use the scratchpad
 974  */
 975 static const struct drbg_state_ops drbg_hash_ops = {
 976         .update         = drbg_hash_update,
 977         .generate       = drbg_hash_generate,
 978         .crypto_init    = drbg_init_hash_kernel,
 979         .crypto_fini    = drbg_fini_hash_kernel,
 980 };
 981 #endif /* CONFIG_CRYPTO_DRBG_HASH */
 982
 983 /******************************************************************
 984  * Functions common for DRBG implementations
 985  ******************************************************************/
 986
 987 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
 988                               int reseed)
 989 {
 990         int ret = drbg->d_ops->update(drbg, seed, reseed);
 991
 992         if (ret)
 993                 return ret;
 994
 995         drbg->seeded = true;
 996         /* 10.1.1.2 / 10.1.1.3 step 5 */
 997         drbg->reseed_ctr = 1;
 998
 999         return ret;
1000 }
1001
1002 static void drbg_async_seed(struct work_struct *work)
1003 {
1004         struct drbg_string data;
1005         LIST_HEAD(seedlist);
1006         struct drbg_state *drbg = container_of(work, struct drbg_state,
1007                                                seed_work);
1008         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1009         unsigned char entropy[32];
1010
1011         BUG_ON(!entropylen);
1012         BUG_ON(entropylen > sizeof(entropy));
1013         get_random_bytes(entropy, entropylen);
1014
1015         drbg_string_fill(&data, entropy, entropylen);
1016         list_add_tail(&data.list, &seedlist);
1017
1018         mutex_lock(&drbg->drbg_mutex);
1019
1020         /* If nonblocking pool is initialized, deactivate Jitter RNG */
1021         crypto_free_rng(drbg->jent);
1022         drbg->jent = NULL;
1023
1024         /* Set seeded to false so that if __drbg_seed fails the
1025          * next generate call will trigger a reseed.
1026          */
1027         drbg->seeded = false;
1028
1029         __drbg_seed(drbg, &seedlist, true);
1030
1031         if (drbg->seeded)
1032                 drbg->reseed_threshold = drbg_max_requests(drbg);
1033
1034         mutex_unlock(&drbg->drbg_mutex);
1035
1036         memzero_explicit(entropy, entropylen);
1037 }
1038
1039 /*
1040  * Seeding or reseeding of the DRBG
1041  *
1042  * @drbg: DRBG state struct
1043  * @pers: personalization / additional information buffer
1044  * @reseed: 0 for initial seed process, 1 for reseeding
1045  *
1046  * return:
1047  *      0 on success
1048  *      error value otherwise
1049  */
1050 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1051                      bool reseed)
1052 {
1053         int ret;
1054         unsigned char entropy[((32 + 16) * 2)];
1055         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1056         struct drbg_string data1;
1057         LIST_HEAD(seedlist);
1058
1059         /* 9.1 / 9.2 / 9.3.1 step 3 */
1060         if (pers && pers->len > (drbg_max_addtl(drbg))) {
1061                 pr_devel("DRBG: personalization string too long %zu\n",
1062                          pers->len);
1063                 return -EINVAL;
1064         }
1065
1066         if (list_empty(&drbg->test_data.list)) {
1067                 drbg_string_fill(&data1, drbg->test_data.buf,
1068                                  drbg->test_data.len);
1069                 pr_devel("DRBG: using test entropy\n");
1070         } else {
1071                 /*
1072                  * Gather entropy equal to the security strength of the DRBG.
1073                  * With a derivation function, a nonce is required in addition
1074                  * to the entropy. A nonce must be at least 1/2 of the security
1075                  * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1076                  * of the strength. The consideration of a nonce is only
1077                  * applicable during initial seeding.
1078                  */
1079                 BUG_ON(!entropylen);
1080                 if (!reseed)
1081                         entropylen = ((entropylen + 1) / 2) * 3;
1082                 BUG_ON((entropylen * 2) > sizeof(entropy));
1083
1084                 /* Get seed from in-kernel /dev/urandom */
1085                 get_random_bytes(entropy, entropylen);
1086
1087                 if (!drbg->jent) {
1088                         drbg_string_fill(&data1, entropy, entropylen);
1089                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1090                                  entropylen);
1091                 } else {
1092                         /* Get seed from Jitter RNG */
1093                         ret = crypto_rng_get_bytes(drbg->jent,
1094                                                    entropy + entropylen,
1095                                                    entropylen);
1096                         if (ret) {
1097                                 pr_devel("DRBG: jent failed with %d\n", ret);
1098                                 return ret;
1099                         }
1100
1101                         drbg_string_fill(&data1, entropy, entropylen * 2);
1102                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1103                                  entropylen * 2);
1104                 }
1105         }
1106         list_add_tail(&data1.list, &seedlist);
1107
1108         /*
1109          * concatenation of entropy with personalization str / addtl input)
1110          * the variable pers is directly handed in by the caller, so check its
1111          * contents whether it is appropriate
1112          */
1113         if (pers && pers->buf && 0 < pers->len) {
1114                 list_add_tail(&pers->list, &seedlist);
1115                 pr_devel("DRBG: using personalization string\n");
1116         }
1117
1118         if (!reseed) {
1119                 memset(drbg->V, 0, drbg_statelen(drbg));
1120                 memset(drbg->C, 0, drbg_statelen(drbg));
1121         }
1122
1123         ret = __drbg_seed(drbg, &seedlist, reseed);
1124
1125         memzero_explicit(entropy, entropylen * 2);
1126
1127         return ret;
1128 }
1129
1130 /* Free all substructures in a DRBG state without the DRBG state structure */
1131 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1132 {
1133         if (!drbg)
1134                 return;
1135         kzfree(drbg->V);
1136         drbg->Vbuf = NULL;
1137         kzfree(drbg->C);
1138         drbg->Cbuf = NULL;
1139         kzfree(drbg->scratchpadbuf);
1140         drbg->scratchpadbuf = NULL;
1141         drbg->reseed_ctr = 0;
1142         drbg->d_ops = NULL;
1143         drbg->core = NULL;
1144 }
1145
1146 /*
1147  * Allocate all sub-structures for a DRBG state.
1148  * The DRBG state structure must already be allocated.
1149  */
1150 static inline int drbg_alloc_state(struct drbg_state *drbg)
1151 {
1152         int ret = -ENOMEM;
1153         unsigned int sb_size = 0;
1154
1155         switch (drbg->core->flags & DRBG_TYPE_MASK) {
1156 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1157         case DRBG_HMAC:
1158                 drbg->d_ops = &drbg_hmac_ops;
1159                 break;
1160 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1161 #ifdef CONFIG_CRYPTO_DRBG_HASH
1162         case DRBG_HASH:
1163                 drbg->d_ops = &drbg_hash_ops;
1164                 break;
1165 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1166 #ifdef CONFIG_CRYPTO_DRBG_CTR
1167         case DRBG_CTR:
1168                 drbg->d_ops = &drbg_ctr_ops;
1169                 break;
1170 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1171         default:
1172                 ret = -EOPNOTSUPP;
1173                 goto err;
1174         }
1175
1176         ret = drbg->d_ops->crypto_init(drbg);
1177         if (ret < 0)
1178                 goto err;
1179
1180         drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1181         if (!drbg->Vbuf)
1182                 goto fini;
1183         drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
1184         drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1185         if (!drbg->Cbuf)
1186                 goto fini;
1187         drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);
1188         /* scratchpad is only generated for CTR and Hash */
1189         if (drbg->core->flags & DRBG_HMAC)
1190                 sb_size = 0;
1191         else if (drbg->core->flags & DRBG_CTR)
1192                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1193                           drbg_statelen(drbg) + /* df_data */
1194                           drbg_blocklen(drbg) + /* pad */
1195                           drbg_blocklen(drbg) + /* iv */
1196                           drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1197         else
1198                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1199
1200         if (0 < sb_size) {
1201                 drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);
1202                 if (!drbg->scratchpadbuf)
1203                         goto fini;
1204                 drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);
1205         }
1206
1207         return 0;
1208
1209 fini:
1210         drbg->d_ops->crypto_fini(drbg);
1211 err:
1212         drbg_dealloc_state(drbg);
1213         return ret;
1214 }
1215
1216 /*************************************************************************
1217  * DRBG interface functions
1218  *************************************************************************/
1219
1220 /*
1221  * DRBG generate function as required by SP800-90A - this function
1222  * generates random numbers
1223  *
1224  * @drbg DRBG state handle
1225  * @buf Buffer where to store the random numbers -- the buffer must already
1226  *      be pre-allocated by caller
1227  * @buflen Length of output buffer - this value defines the number of random
1228  *         bytes pulled from DRBG
1229  * @addtl Additional input that is mixed into state, may be NULL -- note
1230  *        the entropy is pulled by the DRBG internally unconditionally
1231  *        as defined in SP800-90A. The additional input is mixed into
1232  *        the state in addition to the pulled entropy.
1233  *
1234  * return: 0 when all bytes are generated; < 0 in case of an error
1235  */
1236 static int drbg_generate(struct drbg_state *drbg,
1237                          unsigned char *buf, unsigned int buflen,
1238                          struct drbg_string *addtl)
1239 {
1240         int len = 0;
1241         LIST_HEAD(addtllist);
1242
1243         if (!drbg->core) {
1244                 pr_devel("DRBG: not yet seeded\n");
1245                 return -EINVAL;
1246         }
1247         if (0 == buflen || !buf) {
1248                 pr_devel("DRBG: no output buffer provided\n");
1249                 return -EINVAL;
1250         }
1251         if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1252                 pr_devel("DRBG: wrong format of additional information\n");
1253                 return -EINVAL;
1254         }
1255
1256         /* 9.3.1 step 2 */
1257         len = -EINVAL;
1258         if (buflen > (drbg_max_request_bytes(drbg))) {
1259                 pr_devel("DRBG: requested random numbers too large %u\n",
1260                          buflen);
1261                 goto err;
1262         }
1263
1264         /* 9.3.1 step 3 is implicit with the chosen DRBG */
1265
1266         /* 9.3.1 step 4 */
1267         if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1268                 pr_devel("DRBG: additional information string too long %zu\n",
1269                          addtl->len);
1270                 goto err;
1271         }
1272         /* 9.3.1 step 5 is implicit with the chosen DRBG */
1273
1274         /*
1275          * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1276          * here. The spec is a bit convoluted here, we make it simpler.
1277          */
1278         if (drbg->reseed_threshold < drbg->reseed_ctr)
1279                 drbg->seeded = false;
1280
1281         if (drbg->pr || !drbg->seeded) {
1282                 pr_devel("DRBG: reseeding before generation (prediction "
1283                          "resistance: %s, state %s)\n",
1284                          drbg->pr ? "true" : "false",
1285                          drbg->seeded ? "seeded" : "unseeded");
1286                 /* 9.3.1 steps 7.1 through 7.3 */
1287                 len = drbg_seed(drbg, addtl, true);
1288                 if (len)
1289                         goto err;
1290                 /* 9.3.1 step 7.4 */
1291                 addtl = NULL;
1292         }
1293
1294         if (addtl && 0 < addtl->len)
1295                 list_add_tail(&addtl->list, &addtllist);
1296         /* 9.3.1 step 8 and 10 */
1297         len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1298
1299         /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1300         drbg->reseed_ctr++;
1301         if (0 >= len)
1302                 goto err;
1303
1304         /*
1305          * Section 11.3.3 requires to re-perform self tests after some
1306          * generated random numbers. The chosen value after which self
1307          * test is performed is arbitrary, but it should be reasonable.
1308          * However, we do not perform the self tests because of the following
1309          * reasons: it is mathematically impossible that the initial self tests
1310          * were successfully and the following are not. If the initial would
1311          * pass and the following would not, the kernel integrity is violated.
1312          * In this case, the entire kernel operation is questionable and it
1313          * is unlikely that the integrity violation only affects the
1314          * correct operation of the DRBG.
1315          *
1316          * Albeit the following code is commented out, it is provided in
1317          * case somebody has a need to implement the test of 11.3.3.
1318          */
1319 #if 0
1320         if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1321                 int err = 0;
1322                 pr_devel("DRBG: start to perform self test\n");
1323                 if (drbg->core->flags & DRBG_HMAC)
1324                         err = alg_test("drbg_pr_hmac_sha256",
1325                                        "drbg_pr_hmac_sha256", 0, 0);
1326                 else if (drbg->core->flags & DRBG_CTR)
1327                         err = alg_test("drbg_pr_ctr_aes128",
1328                                        "drbg_pr_ctr_aes128", 0, 0);
1329                 else
1330                         err = alg_test("drbg_pr_sha256",
1331                                        "drbg_pr_sha256", 0, 0);
1332                 if (err) {
1333                         pr_err("DRBG: periodical self test failed\n");
1334                         /*
1335                          * uninstantiate implies that from now on, only errors
1336                          * are returned when reusing this DRBG cipher handle
1337                          */
1338                         drbg_uninstantiate(drbg);
1339                         return 0;
1340                 } else {
1341                         pr_devel("DRBG: self test successful\n");
1342                 }
1343         }
1344 #endif
1345
1346         /*
1347          * All operations were successful, return 0 as mandated by
1348          * the kernel crypto API interface.
1349          */
1350         len = 0;
1351 err:
1352         return len;
1353 }
1354
1355 /*
1356  * Wrapper around drbg_generate which can pull arbitrary long strings
1357  * from the DRBG without hitting the maximum request limitation.
1358  *
1359  * Parameters: see drbg_generate
1360  * Return codes: see drbg_generate -- if one drbg_generate request fails,
1361  *               the entire drbg_generate_long request fails
1362  */
1363 static int drbg_generate_long(struct drbg_state *drbg,
1364                               unsigned char *buf, unsigned int buflen,
1365                               struct drbg_string *addtl)
1366 {
1367         unsigned int len = 0;
1368         unsigned int slice = 0;
1369         do {
1370                 int err = 0;
1371                 unsigned int chunk = 0;
1372                 slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1373                 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1374                 mutex_lock(&drbg->drbg_mutex);
1375                 err = drbg_generate(drbg, buf + len, chunk, addtl);
1376                 mutex_unlock(&drbg->drbg_mutex);
1377                 if (0 > err)
1378                         return err;
1379                 len += chunk;
1380         } while (slice > 0 && (len < buflen));
1381         return 0;
1382 }
1383
1384 static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
1385 {
1386         struct drbg_state *drbg = container_of(rdy, struct drbg_state,
1387                                                random_ready);
1388
1389         schedule_work(&drbg->seed_work);
1390 }
1391
1392 static int drbg_prepare_hrng(struct drbg_state *drbg)
1393 {
1394         int err;
1395
1396         /* We do not need an HRNG in test mode. */
1397         if (list_empty(&drbg->test_data.list))
1398                 return 0;
1399
1400         INIT_WORK(&drbg->seed_work, drbg_async_seed);
1401
1402         drbg->random_ready.owner = THIS_MODULE;
1403         drbg->random_ready.func = drbg_schedule_async_seed;
1404
1405         err = add_random_ready_callback(&drbg->random_ready);
1406
1407         switch (err) {
1408         case 0:
1409                 break;
1410
1411         case -EALREADY:
1412                 err = 0;
1413                 /* fall through */
1414
1415         default:
1416                 drbg->random_ready.func = NULL;
1417                 return err;
1418         }
1419
1420         drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
1421
1422         /*
1423          * Require frequent reseeds until the seed source is fully
1424          * initialized.
1425          */
1426         drbg->reseed_threshold = 50;
1427
1428         return err;
1429 }
1430
1431 /*
1432  * DRBG instantiation function as required by SP800-90A - this function
1433  * sets up the DRBG handle, performs the initial seeding and all sanity
1434  * checks required by SP800-90A
1435  *
1436  * @drbg memory of state -- if NULL, new memory is allocated
1437  * @pers Personalization string that is mixed into state, may be NULL -- note
1438  *       the entropy is pulled by the DRBG internally unconditionally
1439  *       as defined in SP800-90A. The additional input is mixed into
1440  *       the state in addition to the pulled entropy.
1441  * @coreref reference to core
1442  * @pr prediction resistance enabled
1443  *
1444  * return
1445  *      0 on success
1446  *      error value otherwise
1447  */
1448 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1449                             int coreref, bool pr)
1450 {
1451         int ret;
1452         bool reseed = true;
1453
1454         pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1455                  "%s\n", coreref, pr ? "enabled" : "disabled");
1456         mutex_lock(&drbg->drbg_mutex);
1457
1458         /* 9.1 step 1 is implicit with the selected DRBG type */
1459
1460         /*
1461          * 9.1 step 2 is implicit as caller can select prediction resistance
1462          * and the flag is copied into drbg->flags --
1463          * all DRBG types support prediction resistance
1464          */
1465
1466         /* 9.1 step 4 is implicit in  drbg_sec_strength */
1467
1468         if (!drbg->core) {
1469                 drbg->core = &drbg_cores[coreref];
1470                 drbg->pr = pr;
1471                 drbg->seeded = false;
1472                 drbg->reseed_threshold = drbg_max_requests(drbg);
1473
1474                 ret = drbg_alloc_state(drbg);
1475                 if (ret)
1476                         goto unlock;
1477
1478                 ret = drbg_prepare_hrng(drbg);
1479                 if (ret)
1480                         goto free_everything;
1481
1482                 if (IS_ERR(drbg->jent)) {
1483                         ret = PTR_ERR(drbg->jent);
1484                         drbg->jent = NULL;
1485                         if (fips_enabled || ret != -ENOENT)
1486                                 goto free_everything;
1487                         pr_info("DRBG: Continuing without Jitter RNG\n");
1488                 }
1489
1490                 reseed = false;
1491         }
1492
1493         ret = drbg_seed(drbg, pers, reseed);
1494
1495         if (ret && !reseed)
1496                 goto free_everything;
1497
1498         mutex_unlock(&drbg->drbg_mutex);
1499         return ret;
1500
1501 unlock:
1502         mutex_unlock(&drbg->drbg_mutex);
1503         return ret;
1504
1505 free_everything:
1506         mutex_unlock(&drbg->drbg_mutex);
1507         drbg_uninstantiate(drbg);
1508         return ret;
1509 }
1510
1511 /*
1512  * DRBG uninstantiate function as required by SP800-90A - this function
1513  * frees all buffers and the DRBG handle
1514  *
1515  * @drbg DRBG state handle
1516  *
1517  * return
1518  *      0 on success
1519  */
1520 static int drbg_uninstantiate(struct drbg_state *drbg)
1521 {
1522         if (drbg->random_ready.func) {
1523                 del_random_ready_callback(&drbg->random_ready);
1524                 cancel_work_sync(&drbg->seed_work);
1525                 crypto_free_rng(drbg->jent);
1526                 drbg->jent = NULL;
1527         }
1528
1529         if (drbg->d_ops)
1530                 drbg->d_ops->crypto_fini(drbg);
1531         drbg_dealloc_state(drbg);
1532         /* no scrubbing of test_data -- this shall survive an uninstantiate */
1533         return 0;
1534 }
1535
1536 /*
1537  * Helper function for setting the test data in the DRBG
1538  *
1539  * @drbg DRBG state handle
1540  * @data test data
1541  * @len test data length
1542  */
1543 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
1544                                    const u8 *data, unsigned int len)
1545 {
1546         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1547
1548         mutex_lock(&drbg->drbg_mutex);
1549         drbg_string_fill(&drbg->test_data, data, len);
1550         mutex_unlock(&drbg->drbg_mutex);
1551 }
1552
1553 /***************************************************************
1554  * Kernel crypto API cipher invocations requested by DRBG
1555  ***************************************************************/
1556
1557 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1558 struct sdesc {
1559         struct shash_desc shash;
1560         char ctx[];
1561 };
1562
1563 static int drbg_init_hash_kernel(struct drbg_state *drbg)
1564 {
1565         struct sdesc *sdesc;
1566         struct crypto_shash *tfm;
1567
1568         tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1569         if (IS_ERR(tfm)) {
1570                 pr_info("DRBG: could not allocate digest TFM handle: %s\n",
1571                                 drbg->core->backend_cra_name);
1572                 return PTR_ERR(tfm);
1573         }
1574         BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1575         sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1576                         GFP_KERNEL);
1577         if (!sdesc) {
1578                 crypto_free_shash(tfm);
1579                 return -ENOMEM;
1580         }
1581
1582         sdesc->shash.tfm = tfm;
1583         sdesc->shash.flags = 0;
1584         drbg->priv_data = sdesc;
1585
1586         return crypto_shash_alignmask(tfm);
1587 }
1588
1589 static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1590 {
1591         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1592         if (sdesc) {
1593                 crypto_free_shash(sdesc->shash.tfm);
1594                 kzfree(sdesc);
1595         }
1596         drbg->priv_data = NULL;
1597         return 0;
1598 }
1599
1600 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
1601                                   const unsigned char *key)
1602 {
1603         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1604
1605         crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
1606 }
1607
1608 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
1609                            const struct list_head *in)
1610 {
1611         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1612         struct drbg_string *input = NULL;
1613
1614         crypto_shash_init(&sdesc->shash);
1615         list_for_each_entry(input, in, list)
1616                 crypto_shash_update(&sdesc->shash, input->buf, input->len);
1617         return crypto_shash_final(&sdesc->shash, outval);
1618 }
1619 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1620
1621 #ifdef CONFIG_CRYPTO_DRBG_CTR
1622 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1623 {
1624         struct crypto_cipher *tfm =
1625                 (struct crypto_cipher *)drbg->priv_data;
1626         if (tfm)
1627                 crypto_free_cipher(tfm);
1628         drbg->priv_data = NULL;
1629
1630         if (drbg->ctr_handle)
1631                 crypto_free_skcipher(drbg->ctr_handle);
1632         drbg->ctr_handle = NULL;
1633
1634         if (drbg->ctr_req)
1635                 skcipher_request_free(drbg->ctr_req);
1636         drbg->ctr_req = NULL;
1637
1638         kfree(drbg->ctr_null_value_buf);
1639         drbg->ctr_null_value = NULL;
1640
1641         return 0;
1642 }
1643
1644 static void drbg_skcipher_cb(struct crypto_async_request *req, int error)
1645 {
1646         struct drbg_state *drbg = req->data;
1647
1648         if (error == -EINPROGRESS)
1649                 return;
1650         drbg->ctr_async_err = error;
1651         complete(&drbg->ctr_completion);
1652 }
1653
1654 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1655 {
1656         struct crypto_cipher *tfm;
1657         struct crypto_skcipher *sk_tfm;
1658         struct skcipher_request *req;
1659         unsigned int alignmask;
1660         char ctr_name[CRYPTO_MAX_ALG_NAME];
1661
1662         tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1663         if (IS_ERR(tfm)) {
1664                 pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1665                                 drbg->core->backend_cra_name);
1666                 return PTR_ERR(tfm);
1667         }
1668         BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1669         drbg->priv_data = tfm;
1670
1671         if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1672             drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1673                 drbg_fini_sym_kernel(drbg);
1674                 return -EINVAL;
1675         }
1676         sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1677         if (IS_ERR(sk_tfm)) {
1678                 pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1679                                 ctr_name);
1680                 drbg_fini_sym_kernel(drbg);
1681                 return PTR_ERR(sk_tfm);
1682         }
1683         drbg->ctr_handle = sk_tfm;
1684
1685         req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1686         if (!req) {
1687                 pr_info("DRBG: could not allocate request queue\n");
1688                 drbg_fini_sym_kernel(drbg);
1689                 return -ENOMEM;
1690         }
1691         drbg->ctr_req = req;
1692         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
1693                                         drbg_skcipher_cb, drbg);
1694
1695         alignmask = crypto_skcipher_alignmask(sk_tfm);
1696         drbg->ctr_null_value_buf = kzalloc(DRBG_CTR_NULL_LEN + alignmask,
1697                                            GFP_KERNEL);
1698         if (!drbg->ctr_null_value_buf) {
1699                 drbg_fini_sym_kernel(drbg);
1700                 return -ENOMEM;
1701         }
1702         drbg->ctr_null_value = (u8 *)PTR_ALIGN(drbg->ctr_null_value_buf,
1703                                                alignmask + 1);
1704
1705         return alignmask;
1706 }
1707
1708 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1709                                  const unsigned char *key)
1710 {
1711         struct crypto_cipher *tfm =
1712                 (struct crypto_cipher *)drbg->priv_data;
1713
1714         crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1715 }
1716
1717 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1718                           const struct drbg_string *in)
1719 {
1720         struct crypto_cipher *tfm =
1721                 (struct crypto_cipher *)drbg->priv_data;
1722
1723         /* there is only component in *in */
1724         BUG_ON(in->len < drbg_blocklen(drbg));
1725         crypto_cipher_encrypt_one(tfm, outval, in->buf);
1726         return 0;
1727 }
1728
1729 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1730                               u8 *inbuf, u32 inlen,
1731                               u8 *outbuf, u32 outlen)
1732 {
1733         struct scatterlist sg_in;
1734
1735         sg_init_one(&sg_in, inbuf, inlen);
1736
1737         while (outlen) {
1738                 u32 cryptlen = min_t(u32, inlen, outlen);
1739                 struct scatterlist sg_out;
1740                 int ret;
1741
1742                 sg_init_one(&sg_out, outbuf, cryptlen);
1743                 skcipher_request_set_crypt(drbg->ctr_req, &sg_in, &sg_out,
1744                                            cryptlen, drbg->V);
1745                 ret = crypto_skcipher_encrypt(drbg->ctr_req);
1746                 switch (ret) {
1747                 case 0:
1748                         break;
1749                 case -EINPROGRESS:
1750                 case -EBUSY:
1751                         ret = wait_for_completion_interruptible(
1752                                 &drbg->ctr_completion);
1753                         if (!ret && !drbg->ctr_async_err) {
1754                                 reinit_completion(&drbg->ctr_completion);
1755                                 break;
1756                         }
1757                 default:
1758                         return ret;
1759                 }
1760                 init_completion(&drbg->ctr_completion);
1761
1762                 outlen -= cryptlen;
1763         }
1764
1765         return 0;
1766 }
1767 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1768
1769 /***************************************************************
1770  * Kernel crypto API interface to register DRBG
1771  ***************************************************************/
1772
1773 /*
1774  * Look up the DRBG flags by given kernel crypto API cra_name
1775  * The code uses the drbg_cores definition to do this
1776  *
1777  * @cra_name kernel crypto API cra_name
1778  * @coreref reference to integer which is filled with the pointer to
1779  *  the applicable core
1780  * @pr reference for setting prediction resistance
1781  *
1782  * return: flags
1783  */
1784 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1785                                          int *coreref, bool *pr)
1786 {
1787         int i = 0;
1788         size_t start = 0;
1789         int len = 0;
1790
1791         *pr = true;
1792         /* disassemble the names */
1793         if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1794                 start = 10;
1795                 *pr = false;
1796         } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1797                 start = 8;
1798         } else {
1799                 return;
1800         }
1801
1802         /* remove the first part */
1803         len = strlen(cra_driver_name) - start;
1804         for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1805                 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1806                             len)) {
1807                         *coreref = i;
1808                         return;
1809                 }
1810         }
1811 }
1812
1813 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1814 {
1815         struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1816
1817         mutex_init(&drbg->drbg_mutex);
1818
1819         return 0;
1820 }
1821
1822 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1823 {
1824         drbg_uninstantiate(crypto_tfm_ctx(tfm));
1825 }
1826
1827 /*
1828  * Generate random numbers invoked by the kernel crypto API:
1829  * The API of the kernel crypto API is extended as follows:
1830  *
1831  * src is additional input supplied to the RNG.
1832  * slen is the length of src.
1833  * dst is the output buffer where random data is to be stored.
1834  * dlen is the length of dst.
1835  */
1836 static int drbg_kcapi_random(struct crypto_rng *tfm,
1837                              const u8 *src, unsigned int slen,
1838                              u8 *dst, unsigned int dlen)
1839 {
1840         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1841         struct drbg_string *addtl = NULL;
1842         struct drbg_string string;
1843
1844         if (slen) {
1845                 /* linked list variable is now local to allow modification */
1846                 drbg_string_fill(&string, src, slen);
1847                 addtl = &string;
1848         }
1849
1850         return drbg_generate_long(drbg, dst, dlen, addtl);
1851 }
1852
1853 /*
1854  * Seed the DRBG invoked by the kernel crypto API
1855  */
1856 static int drbg_kcapi_seed(struct crypto_rng *tfm,
1857                            const u8 *seed, unsigned int slen)
1858 {
1859         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1860         struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1861         bool pr = false;
1862         struct drbg_string string;
1863         struct drbg_string *seed_string = NULL;
1864         int coreref = 0;
1865
1866         drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1867                               &pr);
1868         if (0 < slen) {
1869                 drbg_string_fill(&string, seed, slen);
1870                 seed_string = &string;
1871         }
1872
1873         return drbg_instantiate(drbg, seed_string, coreref, pr);
1874 }
1875
1876 /***************************************************************
1877  * Kernel module: code to load the module
1878  ***************************************************************/
1879
1880 /*
1881  * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1882  * of the error handling.
1883  *
1884  * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1885  * as seed source of get_random_bytes does not fail.
1886  *
1887  * Note 2: There is no sensible way of testing the reseed counter
1888  * enforcement, so skip it.
1889  */
1890 static inline int __init drbg_healthcheck_sanity(void)
1891 {
1892         int len = 0;
1893 #define OUTBUFLEN 16
1894         unsigned char buf[OUTBUFLEN];
1895         struct drbg_state *drbg = NULL;
1896         int ret = -EFAULT;
1897         int rc = -EFAULT;
1898         bool pr = false;
1899         int coreref = 0;
1900         struct drbg_string addtl;
1901         size_t max_addtllen, max_request_bytes;
1902
1903         /* only perform test in FIPS mode */
1904         if (!fips_enabled)
1905                 return 0;
1906
1907 #ifdef CONFIG_CRYPTO_DRBG_CTR
1908         drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1909 #elif defined CONFIG_CRYPTO_DRBG_HASH
1910         drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1911 #else
1912         drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1913 #endif
1914
1915         drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1916         if (!drbg)
1917                 return -ENOMEM;
1918
1919         mutex_init(&drbg->drbg_mutex);
1920
1921         /*
1922          * if the following tests fail, it is likely that there is a buffer
1923          * overflow as buf is much smaller than the requested or provided
1924          * string lengths -- in case the error handling does not succeed
1925          * we may get an OOPS. And we want to get an OOPS as this is a
1926          * grave bug.
1927          */
1928
1929         /* get a valid instance of DRBG for following tests */
1930         ret = drbg_instantiate(drbg, NULL, coreref, pr);
1931         if (ret) {
1932                 rc = ret;
1933                 goto outbuf;
1934         }
1935         max_addtllen = drbg_max_addtl(drbg);
1936         max_request_bytes = drbg_max_request_bytes(drbg);
1937         drbg_string_fill(&addtl, buf, max_addtllen + 1);
1938         /* overflow addtllen with additonal info string */
1939         len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1940         BUG_ON(0 < len);
1941         /* overflow max_bits */
1942         len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1943         BUG_ON(0 < len);
1944         drbg_uninstantiate(drbg);
1945
1946         /* overflow max addtllen with personalization string */
1947         ret = drbg_instantiate(drbg, &addtl, coreref, pr);
1948         BUG_ON(0 == ret);
1949         /* all tests passed */
1950         rc = 0;
1951
1952         pr_devel("DRBG: Sanity tests for failure code paths successfully "
1953                  "completed\n");
1954
1955         drbg_uninstantiate(drbg);
1956 outbuf:
1957         kzfree(drbg);
1958         return rc;
1959 }
1960
1961 static struct rng_alg drbg_algs[22];
1962
1963 /*
1964  * Fill the array drbg_algs used to register the different DRBGs
1965  * with the kernel crypto API. To fill the array, the information
1966  * from drbg_cores[] is used.
1967  */
1968 static inline void __init drbg_fill_array(struct rng_alg *alg,
1969                                           const struct drbg_core *core, int pr)
1970 {
1971         int pos = 0;
1972         static int priority = 200;
1973
1974         memcpy(alg->base.cra_name, "stdrng", 6);
1975         if (pr) {
1976                 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
1977                 pos = 8;
1978         } else {
1979                 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
1980                 pos = 10;
1981         }
1982         memcpy(alg->base.cra_driver_name + pos, core->cra_name,
1983                strlen(core->cra_name));
1984
1985         alg->base.cra_priority = priority;
1986         priority++;
1987         /*
1988          * If FIPS mode enabled, the selected DRBG shall have the
1989          * highest cra_priority over other stdrng instances to ensure
1990          * it is selected.
1991          */
1992         if (fips_enabled)
1993                 alg->base.cra_priority += 200;
1994
1995         alg->base.cra_ctxsize   = sizeof(struct drbg_state);
1996         alg->base.cra_module    = THIS_MODULE;
1997         alg->base.cra_init      = drbg_kcapi_init;
1998         alg->base.cra_exit      = drbg_kcapi_cleanup;
1999         alg->generate           = drbg_kcapi_random;
2000         alg->seed               = drbg_kcapi_seed;
2001         alg->set_ent            = drbg_kcapi_set_entropy;
2002         alg->seedsize           = 0;
2003 }
2004
2005 static int __init drbg_init(void)
2006 {
2007         unsigned int i = 0; /* pointer to drbg_algs */
2008         unsigned int j = 0; /* pointer to drbg_cores */
2009         int ret = -EFAULT;
2010
2011         ret = drbg_healthcheck_sanity();
2012         if (ret)
2013                 return ret;
2014
2015         if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2016                 pr_info("DRBG: Cannot register all DRBG types"
2017                         "(slots needed: %zu, slots available: %zu)\n",
2018                         ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2019                 return ret;
2020         }
2021
2022         /*
2023          * each DRBG definition can be used with PR and without PR, thus
2024          * we instantiate each DRBG in drbg_cores[] twice.
2025          *
2026          * As the order of placing them into the drbg_algs array matters
2027          * (the later DRBGs receive a higher cra_priority) we register the
2028          * prediction resistance DRBGs first as the should not be too
2029          * interesting.
2030          */
2031         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2032                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2033         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2034                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2035         return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2036 }
2037
2038 static void __exit drbg_exit(void)
2039 {
2040         crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2041 }
2042
2043 module_init(drbg_init);
2044 module_exit(drbg_exit);
2045 #ifndef CRYPTO_DRBG_HASH_STRING
2046 #define CRYPTO_DRBG_HASH_STRING ""
2047 #endif
2048 #ifndef CRYPTO_DRBG_HMAC_STRING
2049 #define CRYPTO_DRBG_HMAC_STRING ""
2050 #endif
2051 #ifndef CRYPTO_DRBG_CTR_STRING
2052 #define CRYPTO_DRBG_CTR_STRING ""
2053 #endif
2054 MODULE_LICENSE("GPL");
2055 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2056 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2057                    "using following cores: "
2058                    CRYPTO_DRBG_HASH_STRING
2059                    CRYPTO_DRBG_HMAC_STRING
2060                    CRYPTO_DRBG_CTR_STRING);
2061 MODULE_ALIAS_CRYPTO("stdrng");