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 int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
 256                           unsigned char *outval, const struct drbg_string *in);
 257 static int drbg_init_sym_kernel(struct drbg_state *drbg);
 258 static int drbg_fini_sym_kernel(struct drbg_state *drbg);
 259
 260 /* BCC function for CTR DRBG as defined in 10.4.3 */
 261 static int drbg_ctr_bcc(struct drbg_state *drbg,
 262                         unsigned char *out, const unsigned char *key,
 263                         struct list_head *in)
 264 {
 265         int ret = 0;
 266         struct drbg_string *curr = NULL;
 267         struct drbg_string data;
 268         short cnt = 0;
 269
 270         drbg_string_fill(&data, out, drbg_blocklen(drbg));
 271
 272         /* 10.4.3 step 2 / 4 */
 273         list_for_each_entry(curr, in, list) {
 274                 const unsigned char *pos = curr->buf;
 275                 size_t len = curr->len;
 276                 /* 10.4.3 step 4.1 */
 277                 while (len) {
 278                         /* 10.4.3 step 4.2 */
 279                         if (drbg_blocklen(drbg) == cnt) {
 280                                 cnt = 0;
 281                                 ret = drbg_kcapi_sym(drbg, key, out, &data);
 282                                 if (ret)
 283                                         return ret;
 284                         }
 285                         out[cnt] ^= *pos;
 286                         pos++;
 287                         cnt++;
 288                         len--;
 289                 }
 290         }
 291         /* 10.4.3 step 4.2 for last block */
 292         if (cnt)
 293                 ret = drbg_kcapi_sym(drbg, key, out, &data);
 294
 295         return ret;
 296 }
 297
 298 /*
 299  * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
 300  * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
 301  * the scratchpad is used as follows:
 302  * drbg_ctr_update:
 303  *      temp
 304  *              start: drbg->scratchpad
 305  *              length: drbg_statelen(drbg) + drbg_blocklen(drbg)
 306  *                      note: the cipher writing into this variable works
 307  *                      blocklen-wise. Now, when the statelen is not a multiple
 308  *                      of blocklen, the generateion loop below "spills over"
 309  *                      by at most blocklen. Thus, we need to give sufficient
 310  *                      memory.
 311  *      df_data
 312  *              start: drbg->scratchpad +
 313  *                              drbg_statelen(drbg) + drbg_blocklen(drbg)
 314  *              length: drbg_statelen(drbg)
 315  *
 316  * drbg_ctr_df:
 317  *      pad
 318  *              start: df_data + drbg_statelen(drbg)
 319  *              length: drbg_blocklen(drbg)
 320  *      iv
 321  *              start: pad + drbg_blocklen(drbg)
 322  *              length: drbg_blocklen(drbg)
 323  *      temp
 324  *              start: iv + drbg_blocklen(drbg)
 325  *              length: drbg_satelen(drbg) + drbg_blocklen(drbg)
 326  *                      note: temp is the buffer that the BCC function operates
 327  *                      on. BCC operates blockwise. drbg_statelen(drbg)
 328  *                      is sufficient when the DRBG state length is a multiple
 329  *                      of the block size. For AES192 (and maybe other ciphers)
 330  *                      this is not correct and the length for temp is
 331  *                      insufficient (yes, that also means for such ciphers,
 332  *                      the final output of all BCC rounds are truncated).
 333  *                      Therefore, add drbg_blocklen(drbg) to cover all
 334  *                      possibilities.
 335  */
 336
 337 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
 338 static int drbg_ctr_df(struct drbg_state *drbg,
 339                        unsigned char *df_data, size_t bytes_to_return,
 340                        struct list_head *seedlist)
 341 {
 342         int ret = -EFAULT;
 343         unsigned char L_N[8];
 344         /* S3 is input */
 345         struct drbg_string S1, S2, S4, cipherin;
 346         LIST_HEAD(bcc_list);
 347         unsigned char *pad = df_data + drbg_statelen(drbg);
 348         unsigned char *iv = pad + drbg_blocklen(drbg);
 349         unsigned char *temp = iv + drbg_blocklen(drbg);
 350         size_t padlen = 0;
 351         unsigned int templen = 0;
 352         /* 10.4.2 step 7 */
 353         unsigned int i = 0;
 354         /* 10.4.2 step 8 */
 355         const unsigned char *K = (unsigned char *)
 356                            "\x00\x01\x02\x03\x04\x05\x06\x07"
 357                            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
 358                            "\x10\x11\x12\x13\x14\x15\x16\x17"
 359                            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
 360         unsigned char *X;
 361         size_t generated_len = 0;
 362         size_t inputlen = 0;
 363         struct drbg_string *seed = NULL;
 364
 365         memset(pad, 0, drbg_blocklen(drbg));
 366         memset(iv, 0, drbg_blocklen(drbg));
 367
 368         /* 10.4.2 step 1 is implicit as we work byte-wise */
 369
 370         /* 10.4.2 step 2 */
 371         if ((512/8) < bytes_to_return)
 372                 return -EINVAL;
 373
 374         /* 10.4.2 step 2 -- calculate the entire length of all input data */
 375         list_for_each_entry(seed, seedlist, list)
 376                 inputlen += seed->len;
 377         drbg_cpu_to_be32(inputlen, &L_N[0]);
 378
 379         /* 10.4.2 step 3 */
 380         drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
 381
 382         /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
 383         padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
 384         /* wrap the padlen appropriately */
 385         if (padlen)
 386                 padlen = drbg_blocklen(drbg) - padlen;
 387         /*
 388          * pad / padlen contains the 0x80 byte and the following zero bytes.
 389          * As the calculated padlen value only covers the number of zero
 390          * bytes, this value has to be incremented by one for the 0x80 byte.
 391          */
 392         padlen++;
 393         pad[0] = 0x80;
 394
 395         /* 10.4.2 step 4 -- first fill the linked list and then order it */
 396         drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
 397         list_add_tail(&S1.list, &bcc_list);
 398         drbg_string_fill(&S2, L_N, sizeof(L_N));
 399         list_add_tail(&S2.list, &bcc_list);
 400         list_splice_tail(seedlist, &bcc_list);
 401         drbg_string_fill(&S4, pad, padlen);
 402         list_add_tail(&S4.list, &bcc_list);
 403
 404         /* 10.4.2 step 9 */
 405         while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
 406                 /*
 407                  * 10.4.2 step 9.1 - the padding is implicit as the buffer
 408                  * holds zeros after allocation -- even the increment of i
 409                  * is irrelevant as the increment remains within length of i
 410                  */
 411                 drbg_cpu_to_be32(i, iv);
 412                 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
 413                 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
 414                 if (ret)
 415                         goto out;
 416                 /* 10.4.2 step 9.3 */
 417                 i++;
 418                 templen += drbg_blocklen(drbg);
 419         }
 420
 421         /* 10.4.2 step 11 */
 422         X = temp + (drbg_keylen(drbg));
 423         drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
 424
 425         /* 10.4.2 step 12: overwriting of outval is implemented in next step */
 426
 427         /* 10.4.2 step 13 */
 428         while (generated_len < bytes_to_return) {
 429                 short blocklen = 0;
 430                 /*
 431                  * 10.4.2 step 13.1: the truncation of the key length is
 432                  * implicit as the key is only drbg_blocklen in size based on
 433                  * the implementation of the cipher function callback
 434                  */
 435                 ret = drbg_kcapi_sym(drbg, temp, X, &cipherin);
 436                 if (ret)
 437                         goto out;
 438                 blocklen = (drbg_blocklen(drbg) <
 439                                 (bytes_to_return - generated_len)) ?
 440                             drbg_blocklen(drbg) :
 441                                 (bytes_to_return - generated_len);
 442                 /* 10.4.2 step 13.2 and 14 */
 443                 memcpy(df_data + generated_len, X, blocklen);
 444                 generated_len += blocklen;
 445         }
 446
 447         ret = 0;
 448
 449 out:
 450         memset(iv, 0, drbg_blocklen(drbg));
 451         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 452         memset(pad, 0, drbg_blocklen(drbg));
 453         return ret;
 454 }
 455
 456 /*
 457  * update function of CTR DRBG as defined in 10.2.1.2
 458  *
 459  * The reseed variable has an enhanced meaning compared to the update
 460  * functions of the other DRBGs as follows:
 461  * 0 => initial seed from initialization
 462  * 1 => reseed via drbg_seed
 463  * 2 => first invocation from drbg_ctr_update when addtl is present. In
 464  *      this case, the df_data scratchpad is not deleted so that it is
 465  *      available for another calls to prevent calling the DF function
 466  *      again.
 467  * 3 => second invocation from drbg_ctr_update. When the update function
 468  *      was called with addtl, the df_data memory already contains the
 469  *      DFed addtl information and we do not need to call DF again.
 470  */
 471 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
 472                            int reseed)
 473 {
 474         int ret = -EFAULT;
 475         /* 10.2.1.2 step 1 */
 476         unsigned char *temp = drbg->scratchpad;
 477         unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
 478                                  drbg_blocklen(drbg);
 479         unsigned char *temp_p, *df_data_p; /* pointer to iterate over buffers */
 480         unsigned int len = 0;
 481         struct drbg_string cipherin;
 482
 483         if (3 > reseed)
 484                 memset(df_data, 0, drbg_statelen(drbg));
 485
 486         /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
 487         if (seed) {
 488                 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
 489                 if (ret)
 490                         goto out;
 491         }
 492
 493         drbg_string_fill(&cipherin, drbg->V, drbg_blocklen(drbg));
 494         /*
 495          * 10.2.1.3.2 steps 2 and 3 are already covered as the allocation
 496          * zeroizes all memory during initialization
 497          */
 498         while (len < (drbg_statelen(drbg))) {
 499                 /* 10.2.1.2 step 2.1 */
 500                 crypto_inc(drbg->V, drbg_blocklen(drbg));
 501                 /*
 502                  * 10.2.1.2 step 2.2 */
 503                 ret = drbg_kcapi_sym(drbg, drbg->C, temp + len, &cipherin);
 504                 if (ret)
 505                         goto out;
 506                 /* 10.2.1.2 step 2.3 and 3 */
 507                 len += drbg_blocklen(drbg);
 508         }
 509
 510         /* 10.2.1.2 step 4 */
 511         temp_p = temp;
 512         df_data_p = df_data;
 513         for (len = 0; len < drbg_statelen(drbg); len++) {
 514                 *temp_p ^= *df_data_p;
 515                 df_data_p++; temp_p++;
 516         }
 517
 518         /* 10.2.1.2 step 5 */
 519         memcpy(drbg->C, temp, drbg_keylen(drbg));
 520         /* 10.2.1.2 step 6 */
 521         memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
 522         ret = 0;
 523
 524 out:
 525         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 526         if (2 != reseed)
 527                 memset(df_data, 0, drbg_statelen(drbg));
 528         return ret;
 529 }
 530
 531 /*
 532  * scratchpad use: drbg_ctr_update is called independently from
 533  * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
 534  */
 535 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
 536 static int drbg_ctr_generate(struct drbg_state *drbg,
 537                              unsigned char *buf, unsigned int buflen,
 538                              struct list_head *addtl)
 539 {
 540         int len = 0;
 541         int ret = 0;
 542         struct drbg_string data;
 543
 544         /* 10.2.1.5.2 step 2 */
 545         if (addtl && !list_empty(addtl)) {
 546                 ret = drbg_ctr_update(drbg, addtl, 2);
 547                 if (ret)
 548                         return 0;
 549         }
 550
 551         /* 10.2.1.5.2 step 4.1 */
 552         crypto_inc(drbg->V, drbg_blocklen(drbg));
 553         drbg_string_fill(&data, drbg->V, drbg_blocklen(drbg));
 554         while (len < buflen) {
 555                 int outlen = 0;
 556                 /* 10.2.1.5.2 step 4.2 */
 557                 ret = drbg_kcapi_sym(drbg, drbg->C, drbg->scratchpad, &data);
 558                 if (ret) {
 559                         len = ret;
 560                         goto out;
 561                 }
 562                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 563                           drbg_blocklen(drbg) : (buflen - len);
 564                 /* 10.2.1.5.2 step 4.3 */
 565                 memcpy(buf + len, drbg->scratchpad, outlen);
 566                 len += outlen;
 567                 /* 10.2.1.5.2 step 6 */
 568                 if (len < buflen)
 569                         crypto_inc(drbg->V, drbg_blocklen(drbg));
 570         }
 571
 572         /* 10.2.1.5.2 step 6 */
 573         ret = drbg_ctr_update(drbg, NULL, 3);
 574         if (ret)
 575                 len = ret;
 576
 577 out:
 578         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 579         return len;
 580 }
 581
 582 static const struct drbg_state_ops drbg_ctr_ops = {
 583         .update         = drbg_ctr_update,
 584         .generate       = drbg_ctr_generate,
 585         .crypto_init    = drbg_init_sym_kernel,
 586         .crypto_fini    = drbg_fini_sym_kernel,
 587 };
 588 #endif /* CONFIG_CRYPTO_DRBG_CTR */
 589
 590 /******************************************************************
 591  * HMAC DRBG callback functions
 592  ******************************************************************/
 593
 594 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
 595 static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
 596                            unsigned char *outval, const struct list_head *in);
 597 static int drbg_init_hash_kernel(struct drbg_state *drbg);
 598 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
 599 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
 600
 601 #ifdef CONFIG_CRYPTO_DRBG_HMAC
 602 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
 603 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
 604 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
 605 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
 606 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
 607 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
 608 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
 609 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
 610 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
 611
 612 /* update function of HMAC DRBG as defined in 10.1.2.2 */
 613 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
 614                             int reseed)
 615 {
 616         int ret = -EFAULT;
 617         int i = 0;
 618         struct drbg_string seed1, seed2, vdata;
 619         LIST_HEAD(seedlist);
 620         LIST_HEAD(vdatalist);
 621
 622         if (!reseed)
 623                 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
 624                 memset(drbg->V, 1, drbg_statelen(drbg));
 625
 626         drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
 627         list_add_tail(&seed1.list, &seedlist);
 628         /* buffer of seed2 will be filled in for loop below with one byte */
 629         drbg_string_fill(&seed2, NULL, 1);
 630         list_add_tail(&seed2.list, &seedlist);
 631         /* input data of seed is allowed to be NULL at this point */
 632         if (seed)
 633                 list_splice_tail(seed, &seedlist);
 634
 635         drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
 636         list_add_tail(&vdata.list, &vdatalist);
 637         for (i = 2; 0 < i; i--) {
 638                 /* first round uses 0x0, second 0x1 */
 639                 unsigned char prefix = DRBG_PREFIX0;
 640                 if (1 == i)
 641                         prefix = DRBG_PREFIX1;
 642                 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
 643                 seed2.buf = &prefix;
 644                 ret = drbg_kcapi_hash(drbg, drbg->C, drbg->C, &seedlist);
 645                 if (ret)
 646                         return ret;
 647
 648                 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
 649                 ret = drbg_kcapi_hash(drbg, drbg->C, drbg->V, &vdatalist);
 650                 if (ret)
 651                         return ret;
 652
 653                 /* 10.1.2.2 step 3 */
 654                 if (!seed)
 655                         return ret;
 656         }
 657
 658         return 0;
 659 }
 660
 661 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
 662 static int drbg_hmac_generate(struct drbg_state *drbg,
 663                               unsigned char *buf,
 664                               unsigned int buflen,
 665                               struct list_head *addtl)
 666 {
 667         int len = 0;
 668         int ret = 0;
 669         struct drbg_string data;
 670         LIST_HEAD(datalist);
 671
 672         /* 10.1.2.5 step 2 */
 673         if (addtl && !list_empty(addtl)) {
 674                 ret = drbg_hmac_update(drbg, addtl, 1);
 675                 if (ret)
 676                         return ret;
 677         }
 678
 679         drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
 680         list_add_tail(&data.list, &datalist);
 681         while (len < buflen) {
 682                 unsigned int outlen = 0;
 683                 /* 10.1.2.5 step 4.1 */
 684                 ret = drbg_kcapi_hash(drbg, drbg->C, drbg->V, &datalist);
 685                 if (ret)
 686                         return ret;
 687                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 688                           drbg_blocklen(drbg) : (buflen - len);
 689
 690                 /* 10.1.2.5 step 4.2 */
 691                 memcpy(buf + len, drbg->V, outlen);
 692                 len += outlen;
 693         }
 694
 695         /* 10.1.2.5 step 6 */
 696         if (addtl && !list_empty(addtl))
 697                 ret = drbg_hmac_update(drbg, addtl, 1);
 698         else
 699                 ret = drbg_hmac_update(drbg, NULL, 1);
 700         if (ret)
 701                 return ret;
 702
 703         return len;
 704 }
 705
 706 static const struct drbg_state_ops drbg_hmac_ops = {
 707         .update         = drbg_hmac_update,
 708         .generate       = drbg_hmac_generate,
 709         .crypto_init    = drbg_init_hash_kernel,
 710         .crypto_fini    = drbg_fini_hash_kernel,
 711 };
 712 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
 713
 714 /******************************************************************
 715  * Hash DRBG callback functions
 716  ******************************************************************/
 717
 718 #ifdef CONFIG_CRYPTO_DRBG_HASH
 719 #define CRYPTO_DRBG_HASH_STRING "HASH "
 720 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
 721 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
 722 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
 723 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
 724 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
 725 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
 726 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
 727 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
 728
 729 /*
 730  * Increment buffer
 731  *
 732  * @dst buffer to increment
 733  * @add value to add
 734  */
 735 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
 736                                 const unsigned char *add, size_t addlen)
 737 {
 738         /* implied: dstlen > addlen */
 739         unsigned char *dstptr;
 740         const unsigned char *addptr;
 741         unsigned int remainder = 0;
 742         size_t len = addlen;
 743
 744         dstptr = dst + (dstlen-1);
 745         addptr = add + (addlen-1);
 746         while (len) {
 747                 remainder += *dstptr + *addptr;
 748                 *dstptr = remainder & 0xff;
 749                 remainder >>= 8;
 750                 len--; dstptr--; addptr--;
 751         }
 752         len = dstlen - addlen;
 753         while (len && remainder > 0) {
 754                 remainder = *dstptr + 1;
 755                 *dstptr = remainder & 0xff;
 756                 remainder >>= 8;
 757                 len--; dstptr--;
 758         }
 759 }
 760
 761 /*
 762  * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
 763  * interlinked, the scratchpad is used as follows:
 764  * drbg_hash_update
 765  *      start: drbg->scratchpad
 766  *      length: drbg_statelen(drbg)
 767  * drbg_hash_df:
 768  *      start: drbg->scratchpad + drbg_statelen(drbg)
 769  *      length: drbg_blocklen(drbg)
 770  *
 771  * drbg_hash_process_addtl uses the scratchpad, but fully completes
 772  * before either of the functions mentioned before are invoked. Therefore,
 773  * drbg_hash_process_addtl does not need to be specifically considered.
 774  */
 775
 776 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
 777 static int drbg_hash_df(struct drbg_state *drbg,
 778                         unsigned char *outval, size_t outlen,
 779                         struct list_head *entropylist)
 780 {
 781         int ret = 0;
 782         size_t len = 0;
 783         unsigned char input[5];
 784         unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
 785         struct drbg_string data;
 786
 787         /* 10.4.1 step 3 */
 788         input[0] = 1;
 789         drbg_cpu_to_be32((outlen * 8), &input[1]);
 790
 791         /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
 792         drbg_string_fill(&data, input, 5);
 793         list_add(&data.list, entropylist);
 794
 795         /* 10.4.1 step 4 */
 796         while (len < outlen) {
 797                 short blocklen = 0;
 798                 /* 10.4.1 step 4.1 */
 799                 ret = drbg_kcapi_hash(drbg, NULL, tmp, entropylist);
 800                 if (ret)
 801                         goto out;
 802                 /* 10.4.1 step 4.2 */
 803                 input[0]++;
 804                 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
 805                             drbg_blocklen(drbg) : (outlen - len);
 806                 memcpy(outval + len, tmp, blocklen);
 807                 len += blocklen;
 808         }
 809
 810 out:
 811         memset(tmp, 0, drbg_blocklen(drbg));
 812         return ret;
 813 }
 814
 815 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
 816 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
 817                             int reseed)
 818 {
 819         int ret = 0;
 820         struct drbg_string data1, data2;
 821         LIST_HEAD(datalist);
 822         LIST_HEAD(datalist2);
 823         unsigned char *V = drbg->scratchpad;
 824         unsigned char prefix = DRBG_PREFIX1;
 825
 826         if (!seed)
 827                 return -EINVAL;
 828
 829         if (reseed) {
 830                 /* 10.1.1.3 step 1 */
 831                 memcpy(V, drbg->V, drbg_statelen(drbg));
 832                 drbg_string_fill(&data1, &prefix, 1);
 833                 list_add_tail(&data1.list, &datalist);
 834                 drbg_string_fill(&data2, V, drbg_statelen(drbg));
 835                 list_add_tail(&data2.list, &datalist);
 836         }
 837         list_splice_tail(seed, &datalist);
 838
 839         /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
 840         ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
 841         if (ret)
 842                 goto out;
 843
 844         /* 10.1.1.2 / 10.1.1.3 step 4  */
 845         prefix = DRBG_PREFIX0;
 846         drbg_string_fill(&data1, &prefix, 1);
 847         list_add_tail(&data1.list, &datalist2);
 848         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 849         list_add_tail(&data2.list, &datalist2);
 850         /* 10.1.1.2 / 10.1.1.3 step 4 */
 851         ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
 852
 853 out:
 854         memset(drbg->scratchpad, 0, drbg_statelen(drbg));
 855         return ret;
 856 }
 857
 858 /* processing of additional information string for Hash DRBG */
 859 static int drbg_hash_process_addtl(struct drbg_state *drbg,
 860                                    struct list_head *addtl)
 861 {
 862         int ret = 0;
 863         struct drbg_string data1, data2;
 864         LIST_HEAD(datalist);
 865         unsigned char prefix = DRBG_PREFIX2;
 866
 867         /* 10.1.1.4 step 2 */
 868         if (!addtl || list_empty(addtl))
 869                 return 0;
 870
 871         /* 10.1.1.4 step 2a */
 872         drbg_string_fill(&data1, &prefix, 1);
 873         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 874         list_add_tail(&data1.list, &datalist);
 875         list_add_tail(&data2.list, &datalist);
 876         list_splice_tail(addtl, &datalist);
 877         ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &datalist);
 878         if (ret)
 879                 goto out;
 880
 881         /* 10.1.1.4 step 2b */
 882         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 883                      drbg->scratchpad, drbg_blocklen(drbg));
 884
 885 out:
 886         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 887         return ret;
 888 }
 889
 890 /* Hashgen defined in 10.1.1.4 */
 891 static int drbg_hash_hashgen(struct drbg_state *drbg,
 892                              unsigned char *buf,
 893                              unsigned int buflen)
 894 {
 895         int len = 0;
 896         int ret = 0;
 897         unsigned char *src = drbg->scratchpad;
 898         unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
 899         struct drbg_string data;
 900         LIST_HEAD(datalist);
 901
 902         /* 10.1.1.4 step hashgen 2 */
 903         memcpy(src, drbg->V, drbg_statelen(drbg));
 904
 905         drbg_string_fill(&data, src, drbg_statelen(drbg));
 906         list_add_tail(&data.list, &datalist);
 907         while (len < buflen) {
 908                 unsigned int outlen = 0;
 909                 /* 10.1.1.4 step hashgen 4.1 */
 910                 ret = drbg_kcapi_hash(drbg, NULL, dst, &datalist);
 911                 if (ret) {
 912                         len = ret;
 913                         goto out;
 914                 }
 915                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 916                           drbg_blocklen(drbg) : (buflen - len);
 917                 /* 10.1.1.4 step hashgen 4.2 */
 918                 memcpy(buf + len, dst, outlen);
 919                 len += outlen;
 920                 /* 10.1.1.4 hashgen step 4.3 */
 921                 if (len < buflen)
 922                         crypto_inc(src, drbg_statelen(drbg));
 923         }
 924
 925 out:
 926         memset(drbg->scratchpad, 0,
 927                (drbg_statelen(drbg) + drbg_blocklen(drbg)));
 928         return len;
 929 }
 930
 931 /* generate function for Hash DRBG as defined in  10.1.1.4 */
 932 static int drbg_hash_generate(struct drbg_state *drbg,
 933                               unsigned char *buf, unsigned int buflen,
 934                               struct list_head *addtl)
 935 {
 936         int len = 0;
 937         int ret = 0;
 938         union {
 939                 unsigned char req[8];
 940                 __be64 req_int;
 941         } u;
 942         unsigned char prefix = DRBG_PREFIX3;
 943         struct drbg_string data1, data2;
 944         LIST_HEAD(datalist);
 945
 946         /* 10.1.1.4 step 2 */
 947         ret = drbg_hash_process_addtl(drbg, addtl);
 948         if (ret)
 949                 return ret;
 950         /* 10.1.1.4 step 3 */
 951         len = drbg_hash_hashgen(drbg, buf, buflen);
 952
 953         /* this is the value H as documented in 10.1.1.4 */
 954         /* 10.1.1.4 step 4 */
 955         drbg_string_fill(&data1, &prefix, 1);
 956         list_add_tail(&data1.list, &datalist);
 957         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 958         list_add_tail(&data2.list, &datalist);
 959         ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &datalist);
 960         if (ret) {
 961                 len = ret;
 962                 goto out;
 963         }
 964
 965         /* 10.1.1.4 step 5 */
 966         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 967                      drbg->scratchpad, drbg_blocklen(drbg));
 968         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 969                      drbg->C, drbg_statelen(drbg));
 970         u.req_int = cpu_to_be64(drbg->reseed_ctr);
 971         drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
 972
 973 out:
 974         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 975         return len;
 976 }
 977
 978 /*
 979  * scratchpad usage: as update and generate are used isolated, both
 980  * can use the scratchpad
 981  */
 982 static const struct drbg_state_ops drbg_hash_ops = {
 983         .update         = drbg_hash_update,
 984         .generate       = drbg_hash_generate,
 985         .crypto_init    = drbg_init_hash_kernel,
 986         .crypto_fini    = drbg_fini_hash_kernel,
 987 };
 988 #endif /* CONFIG_CRYPTO_DRBG_HASH */
 989
 990 /******************************************************************
 991  * Functions common for DRBG implementations
 992  ******************************************************************/
 993
 994 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
 995                               int reseed)
 996 {
 997         int ret = drbg->d_ops->update(drbg, seed, reseed);
 998
 999         if (ret)
1000                 return ret;
1001
1002         drbg->seeded = true;
1003         /* 10.1.1.2 / 10.1.1.3 step 5 */
1004         drbg->reseed_ctr = 1;
1005
1006         return ret;
1007 }
1008
1009 static void drbg_async_seed(struct work_struct *work)
1010 {
1011         struct drbg_string data;
1012         LIST_HEAD(seedlist);
1013         struct drbg_state *drbg = container_of(work, struct drbg_state,
1014                                                seed_work);
1015         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1016         unsigned char entropy[32];
1017
1018         BUG_ON(!entropylen);
1019         BUG_ON(entropylen > sizeof(entropy));
1020         get_random_bytes(entropy, entropylen);
1021
1022         drbg_string_fill(&data, entropy, entropylen);
1023         list_add_tail(&data.list, &seedlist);
1024
1025         mutex_lock(&drbg->drbg_mutex);
1026
1027         /* If nonblocking pool is initialized, deactivate Jitter RNG */
1028         crypto_free_rng(drbg->jent);
1029         drbg->jent = NULL;
1030
1031         /* Set seeded to false so that if __drbg_seed fails the
1032          * next generate call will trigger a reseed.
1033          */
1034         drbg->seeded = false;
1035
1036         __drbg_seed(drbg, &seedlist, true);
1037
1038         if (drbg->seeded)
1039                 drbg->reseed_threshold = drbg_max_requests(drbg);
1040
1041         mutex_unlock(&drbg->drbg_mutex);
1042
1043         memzero_explicit(entropy, entropylen);
1044 }
1045
1046 /*
1047  * Seeding or reseeding of the DRBG
1048  *
1049  * @drbg: DRBG state struct
1050  * @pers: personalization / additional information buffer
1051  * @reseed: 0 for initial seed process, 1 for reseeding
1052  *
1053  * return:
1054  *      0 on success
1055  *      error value otherwise
1056  */
1057 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1058                      bool reseed)
1059 {
1060         int ret;
1061         unsigned char entropy[((32 + 16) * 2)];
1062         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1063         struct drbg_string data1;
1064         LIST_HEAD(seedlist);
1065
1066         /* 9.1 / 9.2 / 9.3.1 step 3 */
1067         if (pers && pers->len > (drbg_max_addtl(drbg))) {
1068                 pr_devel("DRBG: personalization string too long %zu\n",
1069                          pers->len);
1070                 return -EINVAL;
1071         }
1072
1073         if (list_empty(&drbg->test_data.list)) {
1074                 drbg_string_fill(&data1, drbg->test_data.buf,
1075                                  drbg->test_data.len);
1076                 pr_devel("DRBG: using test entropy\n");
1077         } else {
1078                 /*
1079                  * Gather entropy equal to the security strength of the DRBG.
1080                  * With a derivation function, a nonce is required in addition
1081                  * to the entropy. A nonce must be at least 1/2 of the security
1082                  * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1083                  * of the strength. The consideration of a nonce is only
1084                  * applicable during initial seeding.
1085                  */
1086                 BUG_ON(!entropylen);
1087                 if (!reseed)
1088                         entropylen = ((entropylen + 1) / 2) * 3;
1089                 BUG_ON((entropylen * 2) > sizeof(entropy));
1090
1091                 /* Get seed from in-kernel /dev/urandom */
1092                 get_random_bytes(entropy, entropylen);
1093
1094                 if (!drbg->jent) {
1095                         drbg_string_fill(&data1, entropy, entropylen);
1096                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1097                                  entropylen);
1098                 } else {
1099                         /* Get seed from Jitter RNG */
1100                         ret = crypto_rng_get_bytes(drbg->jent,
1101                                                    entropy + entropylen,
1102                                                    entropylen);
1103                         if (ret) {
1104                                 pr_devel("DRBG: jent failed with %d\n", ret);
1105                                 return ret;
1106                         }
1107
1108                         drbg_string_fill(&data1, entropy, entropylen * 2);
1109                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1110                                  entropylen * 2);
1111                 }
1112         }
1113         list_add_tail(&data1.list, &seedlist);
1114
1115         /*
1116          * concatenation of entropy with personalization str / addtl input)
1117          * the variable pers is directly handed in by the caller, so check its
1118          * contents whether it is appropriate
1119          */
1120         if (pers && pers->buf && 0 < pers->len) {
1121                 list_add_tail(&pers->list, &seedlist);
1122                 pr_devel("DRBG: using personalization string\n");
1123         }
1124
1125         if (!reseed) {
1126                 memset(drbg->V, 0, drbg_statelen(drbg));
1127                 memset(drbg->C, 0, drbg_statelen(drbg));
1128         }
1129
1130         ret = __drbg_seed(drbg, &seedlist, reseed);
1131
1132         memzero_explicit(entropy, entropylen * 2);
1133
1134         return ret;
1135 }
1136
1137 /* Free all substructures in a DRBG state without the DRBG state structure */
1138 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1139 {
1140         if (!drbg)
1141                 return;
1142         kzfree(drbg->V);
1143         drbg->V = NULL;
1144         kzfree(drbg->C);
1145         drbg->C = NULL;
1146         kzfree(drbg->scratchpad);
1147         drbg->scratchpad = NULL;
1148         drbg->reseed_ctr = 0;
1149         drbg->d_ops = NULL;
1150         drbg->core = NULL;
1151 }
1152
1153 /*
1154  * Allocate all sub-structures for a DRBG state.
1155  * The DRBG state structure must already be allocated.
1156  */
1157 static inline int drbg_alloc_state(struct drbg_state *drbg)
1158 {
1159         int ret = -ENOMEM;
1160         unsigned int sb_size = 0;
1161
1162         switch (drbg->core->flags & DRBG_TYPE_MASK) {
1163 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1164         case DRBG_HMAC:
1165                 drbg->d_ops = &drbg_hmac_ops;
1166                 break;
1167 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1168 #ifdef CONFIG_CRYPTO_DRBG_HASH
1169         case DRBG_HASH:
1170                 drbg->d_ops = &drbg_hash_ops;
1171                 break;
1172 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1173 #ifdef CONFIG_CRYPTO_DRBG_CTR
1174         case DRBG_CTR:
1175                 drbg->d_ops = &drbg_ctr_ops;
1176                 break;
1177 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1178         default:
1179                 ret = -EOPNOTSUPP;
1180                 goto err;
1181         }
1182
1183         drbg->V = kmalloc(drbg_statelen(drbg), GFP_KERNEL);
1184         if (!drbg->V)
1185                 goto err;
1186         drbg->C = kmalloc(drbg_statelen(drbg), GFP_KERNEL);
1187         if (!drbg->C)
1188                 goto err;
1189         /* scratchpad is only generated for CTR and Hash */
1190         if (drbg->core->flags & DRBG_HMAC)
1191                 sb_size = 0;
1192         else if (drbg->core->flags & DRBG_CTR)
1193                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1194                           drbg_statelen(drbg) + /* df_data */
1195                           drbg_blocklen(drbg) + /* pad */
1196                           drbg_blocklen(drbg) + /* iv */
1197                           drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1198         else
1199                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1200
1201         if (0 < sb_size) {
1202                 drbg->scratchpad = kzalloc(sb_size, GFP_KERNEL);
1203                 if (!drbg->scratchpad)
1204                         goto err;
1205         }
1206
1207         return 0;
1208
1209 err:
1210         drbg_dealloc_state(drbg);
1211         return ret;
1212 }
1213
1214 /*************************************************************************
1215  * DRBG interface functions
1216  *************************************************************************/
1217
1218 /*
1219  * DRBG generate function as required by SP800-90A - this function
1220  * generates random numbers
1221  *
1222  * @drbg DRBG state handle
1223  * @buf Buffer where to store the random numbers -- the buffer must already
1224  *      be pre-allocated by caller
1225  * @buflen Length of output buffer - this value defines the number of random
1226  *         bytes pulled from DRBG
1227  * @addtl Additional input that is mixed into state, may be NULL -- note
1228  *        the entropy is pulled by the DRBG internally unconditionally
1229  *        as defined in SP800-90A. The additional input is mixed into
1230  *        the state in addition to the pulled entropy.
1231  *
1232  * return: 0 when all bytes are generated; < 0 in case of an error
1233  */
1234 static int drbg_generate(struct drbg_state *drbg,
1235                          unsigned char *buf, unsigned int buflen,
1236                          struct drbg_string *addtl)
1237 {
1238         int len = 0;
1239         LIST_HEAD(addtllist);
1240
1241         if (!drbg->core) {
1242                 pr_devel("DRBG: not yet seeded\n");
1243                 return -EINVAL;
1244         }
1245         if (0 == buflen || !buf) {
1246                 pr_devel("DRBG: no output buffer provided\n");
1247                 return -EINVAL;
1248         }
1249         if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1250                 pr_devel("DRBG: wrong format of additional information\n");
1251                 return -EINVAL;
1252         }
1253
1254         /* 9.3.1 step 2 */
1255         len = -EINVAL;
1256         if (buflen > (drbg_max_request_bytes(drbg))) {
1257                 pr_devel("DRBG: requested random numbers too large %u\n",
1258                          buflen);
1259                 goto err;
1260         }
1261
1262         /* 9.3.1 step 3 is implicit with the chosen DRBG */
1263
1264         /* 9.3.1 step 4 */
1265         if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1266                 pr_devel("DRBG: additional information string too long %zu\n",
1267                          addtl->len);
1268                 goto err;
1269         }
1270         /* 9.3.1 step 5 is implicit with the chosen DRBG */
1271
1272         /*
1273          * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1274          * here. The spec is a bit convoluted here, we make it simpler.
1275          */
1276         if (drbg->reseed_threshold < drbg->reseed_ctr)
1277                 drbg->seeded = false;
1278
1279         if (drbg->pr || !drbg->seeded) {
1280                 pr_devel("DRBG: reseeding before generation (prediction "
1281                          "resistance: %s, state %s)\n",
1282                          drbg->pr ? "true" : "false",
1283                          drbg->seeded ? "seeded" : "unseeded");
1284                 /* 9.3.1 steps 7.1 through 7.3 */
1285                 len = drbg_seed(drbg, addtl, true);
1286                 if (len)
1287                         goto err;
1288                 /* 9.3.1 step 7.4 */
1289                 addtl = NULL;
1290         }
1291
1292         if (addtl && 0 < addtl->len)
1293                 list_add_tail(&addtl->list, &addtllist);
1294         /* 9.3.1 step 8 and 10 */
1295         len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1296
1297         /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1298         drbg->reseed_ctr++;
1299         if (0 >= len)
1300                 goto err;
1301
1302         /*
1303          * Section 11.3.3 requires to re-perform self tests after some
1304          * generated random numbers. The chosen value after which self
1305          * test is performed is arbitrary, but it should be reasonable.
1306          * However, we do not perform the self tests because of the following
1307          * reasons: it is mathematically impossible that the initial self tests
1308          * were successfully and the following are not. If the initial would
1309          * pass and the following would not, the kernel integrity is violated.
1310          * In this case, the entire kernel operation is questionable and it
1311          * is unlikely that the integrity violation only affects the
1312          * correct operation of the DRBG.
1313          *
1314          * Albeit the following code is commented out, it is provided in
1315          * case somebody has a need to implement the test of 11.3.3.
1316          */
1317 #if 0
1318         if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1319                 int err = 0;
1320                 pr_devel("DRBG: start to perform self test\n");
1321                 if (drbg->core->flags & DRBG_HMAC)
1322                         err = alg_test("drbg_pr_hmac_sha256",
1323                                        "drbg_pr_hmac_sha256", 0, 0);
1324                 else if (drbg->core->flags & DRBG_CTR)
1325                         err = alg_test("drbg_pr_ctr_aes128",
1326                                        "drbg_pr_ctr_aes128", 0, 0);
1327                 else
1328                         err = alg_test("drbg_pr_sha256",
1329                                        "drbg_pr_sha256", 0, 0);
1330                 if (err) {
1331                         pr_err("DRBG: periodical self test failed\n");
1332                         /*
1333                          * uninstantiate implies that from now on, only errors
1334                          * are returned when reusing this DRBG cipher handle
1335                          */
1336                         drbg_uninstantiate(drbg);
1337                         return 0;
1338                 } else {
1339                         pr_devel("DRBG: self test successful\n");
1340                 }
1341         }
1342 #endif
1343
1344         /*
1345          * All operations were successful, return 0 as mandated by
1346          * the kernel crypto API interface.
1347          */
1348         len = 0;
1349 err:
1350         return len;
1351 }
1352
1353 /*
1354  * Wrapper around drbg_generate which can pull arbitrary long strings
1355  * from the DRBG without hitting the maximum request limitation.
1356  *
1357  * Parameters: see drbg_generate
1358  * Return codes: see drbg_generate -- if one drbg_generate request fails,
1359  *               the entire drbg_generate_long request fails
1360  */
1361 static int drbg_generate_long(struct drbg_state *drbg,
1362                               unsigned char *buf, unsigned int buflen,
1363                               struct drbg_string *addtl)
1364 {
1365         unsigned int len = 0;
1366         unsigned int slice = 0;
1367         do {
1368                 int err = 0;
1369                 unsigned int chunk = 0;
1370                 slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1371                 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1372                 mutex_lock(&drbg->drbg_mutex);
1373                 err = drbg_generate(drbg, buf + len, chunk, addtl);
1374                 mutex_unlock(&drbg->drbg_mutex);
1375                 if (0 > err)
1376                         return err;
1377                 len += chunk;
1378         } while (slice > 0 && (len < buflen));
1379         return 0;
1380 }
1381
1382 static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
1383 {
1384         struct drbg_state *drbg = container_of(rdy, struct drbg_state,
1385                                                random_ready);
1386
1387         schedule_work(&drbg->seed_work);
1388 }
1389
1390 static int drbg_prepare_hrng(struct drbg_state *drbg)
1391 {
1392         int err;
1393
1394         /* We do not need an HRNG in test mode. */
1395         if (list_empty(&drbg->test_data.list))
1396                 return 0;
1397
1398         INIT_WORK(&drbg->seed_work, drbg_async_seed);
1399
1400         drbg->random_ready.owner = THIS_MODULE;
1401         drbg->random_ready.func = drbg_schedule_async_seed;
1402
1403         err = add_random_ready_callback(&drbg->random_ready);
1404
1405         switch (err) {
1406         case 0:
1407                 break;
1408
1409         case -EALREADY:
1410                 err = 0;
1411                 /* fall through */
1412
1413         default:
1414                 drbg->random_ready.func = NULL;
1415                 return err;
1416         }
1417
1418         drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
1419
1420         /*
1421          * Require frequent reseeds until the seed source is fully
1422          * initialized.
1423          */
1424         drbg->reseed_threshold = 50;
1425
1426         return err;
1427 }
1428
1429 /*
1430  * DRBG instantiation function as required by SP800-90A - this function
1431  * sets up the DRBG handle, performs the initial seeding and all sanity
1432  * checks required by SP800-90A
1433  *
1434  * @drbg memory of state -- if NULL, new memory is allocated
1435  * @pers Personalization string that is mixed into state, may be NULL -- note
1436  *       the entropy is pulled by the DRBG internally unconditionally
1437  *       as defined in SP800-90A. The additional input is mixed into
1438  *       the state in addition to the pulled entropy.
1439  * @coreref reference to core
1440  * @pr prediction resistance enabled
1441  *
1442  * return
1443  *      0 on success
1444  *      error value otherwise
1445  */
1446 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1447                             int coreref, bool pr)
1448 {
1449         int ret;
1450         bool reseed = true;
1451
1452         pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1453                  "%s\n", coreref, pr ? "enabled" : "disabled");
1454         mutex_lock(&drbg->drbg_mutex);
1455
1456         /* 9.1 step 1 is implicit with the selected DRBG type */
1457
1458         /*
1459          * 9.1 step 2 is implicit as caller can select prediction resistance
1460          * and the flag is copied into drbg->flags --
1461          * all DRBG types support prediction resistance
1462          */
1463
1464         /* 9.1 step 4 is implicit in  drbg_sec_strength */
1465
1466         if (!drbg->core) {
1467                 drbg->core = &drbg_cores[coreref];
1468                 drbg->pr = pr;
1469                 drbg->seeded = false;
1470                 drbg->reseed_threshold = drbg_max_requests(drbg);
1471
1472                 ret = drbg_alloc_state(drbg);
1473                 if (ret)
1474                         goto unlock;
1475
1476                 ret = -EFAULT;
1477                 if (drbg->d_ops->crypto_init(drbg))
1478                         goto err;
1479
1480                 ret = drbg_prepare_hrng(drbg);
1481                 if (ret)
1482                         goto free_everything;
1483
1484                 if (IS_ERR(drbg->jent)) {
1485                         ret = PTR_ERR(drbg->jent);
1486                         drbg->jent = NULL;
1487                         if (fips_enabled || ret != -ENOENT)
1488                                 goto free_everything;
1489                         pr_info("DRBG: Continuing without Jitter RNG\n");
1490                 }
1491
1492                 reseed = false;
1493         }
1494
1495         ret = drbg_seed(drbg, pers, reseed);
1496
1497         if (ret && !reseed)
1498                 goto free_everything;
1499
1500         mutex_unlock(&drbg->drbg_mutex);
1501         return ret;
1502
1503 err:
1504         drbg_dealloc_state(drbg);
1505 unlock:
1506         mutex_unlock(&drbg->drbg_mutex);
1507         return ret;
1508
1509 free_everything:
1510         mutex_unlock(&drbg->drbg_mutex);
1511         drbg_uninstantiate(drbg);
1512         return ret;
1513 }
1514
1515 /*
1516  * DRBG uninstantiate function as required by SP800-90A - this function
1517  * frees all buffers and the DRBG handle
1518  *
1519  * @drbg DRBG state handle
1520  *
1521  * return
1522  *      0 on success
1523  */
1524 static int drbg_uninstantiate(struct drbg_state *drbg)
1525 {
1526         if (drbg->random_ready.func) {
1527                 del_random_ready_callback(&drbg->random_ready);
1528                 cancel_work_sync(&drbg->seed_work);
1529                 crypto_free_rng(drbg->jent);
1530                 drbg->jent = NULL;
1531         }
1532
1533         if (drbg->d_ops)
1534                 drbg->d_ops->crypto_fini(drbg);
1535         drbg_dealloc_state(drbg);
1536         /* no scrubbing of test_data -- this shall survive an uninstantiate */
1537         return 0;
1538 }
1539
1540 /*
1541  * Helper function for setting the test data in the DRBG
1542  *
1543  * @drbg DRBG state handle
1544  * @data test data
1545  * @len test data length
1546  */
1547 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
1548                                    const u8 *data, unsigned int len)
1549 {
1550         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1551
1552         mutex_lock(&drbg->drbg_mutex);
1553         drbg_string_fill(&drbg->test_data, data, len);
1554         mutex_unlock(&drbg->drbg_mutex);
1555 }
1556
1557 /***************************************************************
1558  * Kernel crypto API cipher invocations requested by DRBG
1559  ***************************************************************/
1560
1561 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1562 struct sdesc {
1563         struct shash_desc shash;
1564         char ctx[];
1565 };
1566
1567 static int drbg_init_hash_kernel(struct drbg_state *drbg)
1568 {
1569         struct sdesc *sdesc;
1570         struct crypto_shash *tfm;
1571
1572         tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1573         if (IS_ERR(tfm)) {
1574                 pr_info("DRBG: could not allocate digest TFM handle: %s\n",
1575                                 drbg->core->backend_cra_name);
1576                 return PTR_ERR(tfm);
1577         }
1578         BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1579         sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1580                         GFP_KERNEL);
1581         if (!sdesc) {
1582                 crypto_free_shash(tfm);
1583                 return -ENOMEM;
1584         }
1585
1586         sdesc->shash.tfm = tfm;
1587         sdesc->shash.flags = 0;
1588         drbg->priv_data = sdesc;
1589         return 0;
1590 }
1591
1592 static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1593 {
1594         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1595         if (sdesc) {
1596                 crypto_free_shash(sdesc->shash.tfm);
1597                 kzfree(sdesc);
1598         }
1599         drbg->priv_data = NULL;
1600         return 0;
1601 }
1602
1603 static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
1604                            unsigned char *outval, const struct list_head *in)
1605 {
1606         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1607         struct drbg_string *input = NULL;
1608
1609         if (key)
1610                 crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
1611         crypto_shash_init(&sdesc->shash);
1612         list_for_each_entry(input, in, list)
1613                 crypto_shash_update(&sdesc->shash, input->buf, input->len);
1614         return crypto_shash_final(&sdesc->shash, outval);
1615 }
1616 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1617
1618 #ifdef CONFIG_CRYPTO_DRBG_CTR
1619 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1620 {
1621         int ret = 0;
1622         struct crypto_cipher *tfm;
1623
1624         tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1625         if (IS_ERR(tfm)) {
1626                 pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1627                                 drbg->core->backend_cra_name);
1628                 return PTR_ERR(tfm);
1629         }
1630         BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1631         drbg->priv_data = tfm;
1632         return ret;
1633 }
1634
1635 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1636 {
1637         struct crypto_cipher *tfm =
1638                 (struct crypto_cipher *)drbg->priv_data;
1639         if (tfm)
1640                 crypto_free_cipher(tfm);
1641         drbg->priv_data = NULL;
1642         return 0;
1643 }
1644
1645 static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
1646                           unsigned char *outval, const struct drbg_string *in)
1647 {
1648         struct crypto_cipher *tfm =
1649                 (struct crypto_cipher *)drbg->priv_data;
1650
1651         crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1652         /* there is only component in *in */
1653         BUG_ON(in->len < drbg_blocklen(drbg));
1654         crypto_cipher_encrypt_one(tfm, outval, in->buf);
1655         return 0;
1656 }
1657 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1658
1659 /***************************************************************
1660  * Kernel crypto API interface to register DRBG
1661  ***************************************************************/
1662
1663 /*
1664  * Look up the DRBG flags by given kernel crypto API cra_name
1665  * The code uses the drbg_cores definition to do this
1666  *
1667  * @cra_name kernel crypto API cra_name
1668  * @coreref reference to integer which is filled with the pointer to
1669  *  the applicable core
1670  * @pr reference for setting prediction resistance
1671  *
1672  * return: flags
1673  */
1674 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1675                                          int *coreref, bool *pr)
1676 {
1677         int i = 0;
1678         size_t start = 0;
1679         int len = 0;
1680
1681         *pr = true;
1682         /* disassemble the names */
1683         if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1684                 start = 10;
1685                 *pr = false;
1686         } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1687                 start = 8;
1688         } else {
1689                 return;
1690         }
1691
1692         /* remove the first part */
1693         len = strlen(cra_driver_name) - start;
1694         for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1695                 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1696                             len)) {
1697                         *coreref = i;
1698                         return;
1699                 }
1700         }
1701 }
1702
1703 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1704 {
1705         struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1706
1707         mutex_init(&drbg->drbg_mutex);
1708
1709         return 0;
1710 }
1711
1712 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1713 {
1714         drbg_uninstantiate(crypto_tfm_ctx(tfm));
1715 }
1716
1717 /*
1718  * Generate random numbers invoked by the kernel crypto API:
1719  * The API of the kernel crypto API is extended as follows:
1720  *
1721  * src is additional input supplied to the RNG.
1722  * slen is the length of src.
1723  * dst is the output buffer where random data is to be stored.
1724  * dlen is the length of dst.
1725  */
1726 static int drbg_kcapi_random(struct crypto_rng *tfm,
1727                              const u8 *src, unsigned int slen,
1728                              u8 *dst, unsigned int dlen)
1729 {
1730         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1731         struct drbg_string *addtl = NULL;
1732         struct drbg_string string;
1733
1734         if (slen) {
1735                 /* linked list variable is now local to allow modification */
1736                 drbg_string_fill(&string, src, slen);
1737                 addtl = &string;
1738         }
1739
1740         return drbg_generate_long(drbg, dst, dlen, addtl);
1741 }
1742
1743 /*
1744  * Seed the DRBG invoked by the kernel crypto API
1745  */
1746 static int drbg_kcapi_seed(struct crypto_rng *tfm,
1747                            const u8 *seed, unsigned int slen)
1748 {
1749         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1750         struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1751         bool pr = false;
1752         struct drbg_string string;
1753         struct drbg_string *seed_string = NULL;
1754         int coreref = 0;
1755
1756         drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1757                               &pr);
1758         if (0 < slen) {
1759                 drbg_string_fill(&string, seed, slen);
1760                 seed_string = &string;
1761         }
1762
1763         return drbg_instantiate(drbg, seed_string, coreref, pr);
1764 }
1765
1766 /***************************************************************
1767  * Kernel module: code to load the module
1768  ***************************************************************/
1769
1770 /*
1771  * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1772  * of the error handling.
1773  *
1774  * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1775  * as seed source of get_random_bytes does not fail.
1776  *
1777  * Note 2: There is no sensible way of testing the reseed counter
1778  * enforcement, so skip it.
1779  */
1780 static inline int __init drbg_healthcheck_sanity(void)
1781 {
1782         int len = 0;
1783 #define OUTBUFLEN 16
1784         unsigned char buf[OUTBUFLEN];
1785         struct drbg_state *drbg = NULL;
1786         int ret = -EFAULT;
1787         int rc = -EFAULT;
1788         bool pr = false;
1789         int coreref = 0;
1790         struct drbg_string addtl;
1791         size_t max_addtllen, max_request_bytes;
1792
1793         /* only perform test in FIPS mode */
1794         if (!fips_enabled)
1795                 return 0;
1796
1797 #ifdef CONFIG_CRYPTO_DRBG_CTR
1798         drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1799 #elif defined CONFIG_CRYPTO_DRBG_HASH
1800         drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1801 #else
1802         drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1803 #endif
1804
1805         drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1806         if (!drbg)
1807                 return -ENOMEM;
1808
1809         mutex_init(&drbg->drbg_mutex);
1810
1811         /*
1812          * if the following tests fail, it is likely that there is a buffer
1813          * overflow as buf is much smaller than the requested or provided
1814          * string lengths -- in case the error handling does not succeed
1815          * we may get an OOPS. And we want to get an OOPS as this is a
1816          * grave bug.
1817          */
1818
1819         /* get a valid instance of DRBG for following tests */
1820         ret = drbg_instantiate(drbg, NULL, coreref, pr);
1821         if (ret) {
1822                 rc = ret;
1823                 goto outbuf;
1824         }
1825         max_addtllen = drbg_max_addtl(drbg);
1826         max_request_bytes = drbg_max_request_bytes(drbg);
1827         drbg_string_fill(&addtl, buf, max_addtllen + 1);
1828         /* overflow addtllen with additonal info string */
1829         len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1830         BUG_ON(0 < len);
1831         /* overflow max_bits */
1832         len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1833         BUG_ON(0 < len);
1834         drbg_uninstantiate(drbg);
1835
1836         /* overflow max addtllen with personalization string */
1837         ret = drbg_instantiate(drbg, &addtl, coreref, pr);
1838         BUG_ON(0 == ret);
1839         /* all tests passed */
1840         rc = 0;
1841
1842         pr_devel("DRBG: Sanity tests for failure code paths successfully "
1843                  "completed\n");
1844
1845         drbg_uninstantiate(drbg);
1846 outbuf:
1847         kzfree(drbg);
1848         return rc;
1849 }
1850
1851 static struct rng_alg drbg_algs[22];
1852
1853 /*
1854  * Fill the array drbg_algs used to register the different DRBGs
1855  * with the kernel crypto API. To fill the array, the information
1856  * from drbg_cores[] is used.
1857  */
1858 static inline void __init drbg_fill_array(struct rng_alg *alg,
1859                                           const struct drbg_core *core, int pr)
1860 {
1861         int pos = 0;
1862         static int priority = 200;
1863
1864         memcpy(alg->base.cra_name, "stdrng", 6);
1865         if (pr) {
1866                 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
1867                 pos = 8;
1868         } else {
1869                 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
1870                 pos = 10;
1871         }
1872         memcpy(alg->base.cra_driver_name + pos, core->cra_name,
1873                strlen(core->cra_name));
1874
1875         alg->base.cra_priority = priority;
1876         priority++;
1877         /*
1878          * If FIPS mode enabled, the selected DRBG shall have the
1879          * highest cra_priority over other stdrng instances to ensure
1880          * it is selected.
1881          */
1882         if (fips_enabled)
1883                 alg->base.cra_priority += 200;
1884
1885         alg->base.cra_ctxsize   = sizeof(struct drbg_state);
1886         alg->base.cra_module    = THIS_MODULE;
1887         alg->base.cra_init      = drbg_kcapi_init;
1888         alg->base.cra_exit      = drbg_kcapi_cleanup;
1889         alg->generate           = drbg_kcapi_random;
1890         alg->seed               = drbg_kcapi_seed;
1891         alg->set_ent            = drbg_kcapi_set_entropy;
1892         alg->seedsize           = 0;
1893 }
1894
1895 static int __init drbg_init(void)
1896 {
1897         unsigned int i = 0; /* pointer to drbg_algs */
1898         unsigned int j = 0; /* pointer to drbg_cores */
1899         int ret = -EFAULT;
1900
1901         ret = drbg_healthcheck_sanity();
1902         if (ret)
1903                 return ret;
1904
1905         if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
1906                 pr_info("DRBG: Cannot register all DRBG types"
1907                         "(slots needed: %zu, slots available: %zu)\n",
1908                         ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
1909                 return ret;
1910         }
1911
1912         /*
1913          * each DRBG definition can be used with PR and without PR, thus
1914          * we instantiate each DRBG in drbg_cores[] twice.
1915          *
1916          * As the order of placing them into the drbg_algs array matters
1917          * (the later DRBGs receive a higher cra_priority) we register the
1918          * prediction resistance DRBGs first as the should not be too
1919          * interesting.
1920          */
1921         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
1922                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
1923         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
1924                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
1925         return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
1926 }
1927
1928 static void __exit drbg_exit(void)
1929 {
1930         crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
1931 }
1932
1933 module_init(drbg_init);
1934 module_exit(drbg_exit);
1935 #ifndef CRYPTO_DRBG_HASH_STRING
1936 #define CRYPTO_DRBG_HASH_STRING ""
1937 #endif
1938 #ifndef CRYPTO_DRBG_HMAC_STRING
1939 #define CRYPTO_DRBG_HMAC_STRING ""
1940 #endif
1941 #ifndef CRYPTO_DRBG_CTR_STRING
1942 #define CRYPTO_DRBG_CTR_STRING ""
1943 #endif
1944 MODULE_LICENSE("GPL");
1945 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
1946 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
1947                    "using following cores: "
1948                    CRYPTO_DRBG_HASH_STRING
1949                    CRYPTO_DRBG_HMAC_STRING
1950                    CRYPTO_DRBG_CTR_STRING);
1951 MODULE_ALIAS_CRYPTO("stdrng");