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 #define DRBG_OUTSCRATCHLEN DRBG_CTR_NULL_LEN
 266
 267 /* BCC function for CTR DRBG as defined in 10.4.3 */
 268 static int drbg_ctr_bcc(struct drbg_state *drbg,
 269                         unsigned char *out, const unsigned char *key,
 270                         struct list_head *in)
 271 {
 272         int ret = 0;
 273         struct drbg_string *curr = NULL;
 274         struct drbg_string data;
 275         short cnt = 0;
 276
 277         drbg_string_fill(&data, out, drbg_blocklen(drbg));
 278
 279         /* 10.4.3 step 2 / 4 */
 280         drbg_kcapi_symsetkey(drbg, key);
 281         list_for_each_entry(curr, in, list) {
 282                 const unsigned char *pos = curr->buf;
 283                 size_t len = curr->len;
 284                 /* 10.4.3 step 4.1 */
 285                 while (len) {
 286                         /* 10.4.3 step 4.2 */
 287                         if (drbg_blocklen(drbg) == cnt) {
 288                                 cnt = 0;
 289                                 ret = drbg_kcapi_sym(drbg, out, &data);
 290                                 if (ret)
 291                                         return ret;
 292                         }
 293                         out[cnt] ^= *pos;
 294                         pos++;
 295                         cnt++;
 296                         len--;
 297                 }
 298         }
 299         /* 10.4.3 step 4.2 for last block */
 300         if (cnt)
 301                 ret = drbg_kcapi_sym(drbg, out, &data);
 302
 303         return ret;
 304 }
 305
 306 /*
 307  * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
 308  * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
 309  * the scratchpad is used as follows:
 310  * drbg_ctr_update:
 311  *      temp
 312  *              start: drbg->scratchpad
 313  *              length: drbg_statelen(drbg) + drbg_blocklen(drbg)
 314  *                      note: the cipher writing into this variable works
 315  *                      blocklen-wise. Now, when the statelen is not a multiple
 316  *                      of blocklen, the generateion loop below "spills over"
 317  *                      by at most blocklen. Thus, we need to give sufficient
 318  *                      memory.
 319  *      df_data
 320  *              start: drbg->scratchpad +
 321  *                              drbg_statelen(drbg) + drbg_blocklen(drbg)
 322  *              length: drbg_statelen(drbg)
 323  *
 324  * drbg_ctr_df:
 325  *      pad
 326  *              start: df_data + drbg_statelen(drbg)
 327  *              length: drbg_blocklen(drbg)
 328  *      iv
 329  *              start: pad + drbg_blocklen(drbg)
 330  *              length: drbg_blocklen(drbg)
 331  *      temp
 332  *              start: iv + drbg_blocklen(drbg)
 333  *              length: drbg_satelen(drbg) + drbg_blocklen(drbg)
 334  *                      note: temp is the buffer that the BCC function operates
 335  *                      on. BCC operates blockwise. drbg_statelen(drbg)
 336  *                      is sufficient when the DRBG state length is a multiple
 337  *                      of the block size. For AES192 (and maybe other ciphers)
 338  *                      this is not correct and the length for temp is
 339  *                      insufficient (yes, that also means for such ciphers,
 340  *                      the final output of all BCC rounds are truncated).
 341  *                      Therefore, add drbg_blocklen(drbg) to cover all
 342  *                      possibilities.
 343  */
 344
 345 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
 346 static int drbg_ctr_df(struct drbg_state *drbg,
 347                        unsigned char *df_data, size_t bytes_to_return,
 348                        struct list_head *seedlist)
 349 {
 350         int ret = -EFAULT;
 351         unsigned char L_N[8];
 352         /* S3 is input */
 353         struct drbg_string S1, S2, S4, cipherin;
 354         LIST_HEAD(bcc_list);
 355         unsigned char *pad = df_data + drbg_statelen(drbg);
 356         unsigned char *iv = pad + drbg_blocklen(drbg);
 357         unsigned char *temp = iv + drbg_blocklen(drbg);
 358         size_t padlen = 0;
 359         unsigned int templen = 0;
 360         /* 10.4.2 step 7 */
 361         unsigned int i = 0;
 362         /* 10.4.2 step 8 */
 363         const unsigned char *K = (unsigned char *)
 364                            "\x00\x01\x02\x03\x04\x05\x06\x07"
 365                            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
 366                            "\x10\x11\x12\x13\x14\x15\x16\x17"
 367                            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
 368         unsigned char *X;
 369         size_t generated_len = 0;
 370         size_t inputlen = 0;
 371         struct drbg_string *seed = NULL;
 372
 373         memset(pad, 0, drbg_blocklen(drbg));
 374         memset(iv, 0, drbg_blocklen(drbg));
 375
 376         /* 10.4.2 step 1 is implicit as we work byte-wise */
 377
 378         /* 10.4.2 step 2 */
 379         if ((512/8) < bytes_to_return)
 380                 return -EINVAL;
 381
 382         /* 10.4.2 step 2 -- calculate the entire length of all input data */
 383         list_for_each_entry(seed, seedlist, list)
 384                 inputlen += seed->len;
 385         drbg_cpu_to_be32(inputlen, &L_N[0]);
 386
 387         /* 10.4.2 step 3 */
 388         drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
 389
 390         /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
 391         padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
 392         /* wrap the padlen appropriately */
 393         if (padlen)
 394                 padlen = drbg_blocklen(drbg) - padlen;
 395         /*
 396          * pad / padlen contains the 0x80 byte and the following zero bytes.
 397          * As the calculated padlen value only covers the number of zero
 398          * bytes, this value has to be incremented by one for the 0x80 byte.
 399          */
 400         padlen++;
 401         pad[0] = 0x80;
 402
 403         /* 10.4.2 step 4 -- first fill the linked list and then order it */
 404         drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
 405         list_add_tail(&S1.list, &bcc_list);
 406         drbg_string_fill(&S2, L_N, sizeof(L_N));
 407         list_add_tail(&S2.list, &bcc_list);
 408         list_splice_tail(seedlist, &bcc_list);
 409         drbg_string_fill(&S4, pad, padlen);
 410         list_add_tail(&S4.list, &bcc_list);
 411
 412         /* 10.4.2 step 9 */
 413         while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
 414                 /*
 415                  * 10.4.2 step 9.1 - the padding is implicit as the buffer
 416                  * holds zeros after allocation -- even the increment of i
 417                  * is irrelevant as the increment remains within length of i
 418                  */
 419                 drbg_cpu_to_be32(i, iv);
 420                 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
 421                 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
 422                 if (ret)
 423                         goto out;
 424                 /* 10.4.2 step 9.3 */
 425                 i++;
 426                 templen += drbg_blocklen(drbg);
 427         }
 428
 429         /* 10.4.2 step 11 */
 430         X = temp + (drbg_keylen(drbg));
 431         drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
 432
 433         /* 10.4.2 step 12: overwriting of outval is implemented in next step */
 434
 435         /* 10.4.2 step 13 */
 436         drbg_kcapi_symsetkey(drbg, temp);
 437         while (generated_len < bytes_to_return) {
 438                 short blocklen = 0;
 439                 /*
 440                  * 10.4.2 step 13.1: the truncation of the key length is
 441                  * implicit as the key is only drbg_blocklen in size based on
 442                  * the implementation of the cipher function callback
 443                  */
 444                 ret = drbg_kcapi_sym(drbg, X, &cipherin);
 445                 if (ret)
 446                         goto out;
 447                 blocklen = (drbg_blocklen(drbg) <
 448                                 (bytes_to_return - generated_len)) ?
 449                             drbg_blocklen(drbg) :
 450                                 (bytes_to_return - generated_len);
 451                 /* 10.4.2 step 13.2 and 14 */
 452                 memcpy(df_data + generated_len, X, blocklen);
 453                 generated_len += blocklen;
 454         }
 455
 456         ret = 0;
 457
 458 out:
 459         memset(iv, 0, drbg_blocklen(drbg));
 460         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 461         memset(pad, 0, drbg_blocklen(drbg));
 462         return ret;
 463 }
 464
 465 /*
 466  * update function of CTR DRBG as defined in 10.2.1.2
 467  *
 468  * The reseed variable has an enhanced meaning compared to the update
 469  * functions of the other DRBGs as follows:
 470  * 0 => initial seed from initialization
 471  * 1 => reseed via drbg_seed
 472  * 2 => first invocation from drbg_ctr_update when addtl is present. In
 473  *      this case, the df_data scratchpad is not deleted so that it is
 474  *      available for another calls to prevent calling the DF function
 475  *      again.
 476  * 3 => second invocation from drbg_ctr_update. When the update function
 477  *      was called with addtl, the df_data memory already contains the
 478  *      DFed addtl information and we do not need to call DF again.
 479  */
 480 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
 481                            int reseed)
 482 {
 483         int ret = -EFAULT;
 484         /* 10.2.1.2 step 1 */
 485         unsigned char *temp = drbg->scratchpad;
 486         unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
 487                                  drbg_blocklen(drbg);
 488
 489         if (3 > reseed)
 490                 memset(df_data, 0, drbg_statelen(drbg));
 491
 492         if (!reseed) {
 493                 /*
 494                  * The DRBG uses the CTR mode of the underlying AES cipher. The
 495                  * CTR mode increments the counter value after the AES operation
 496                  * but SP800-90A requires that the counter is incremented before
 497                  * the AES operation. Hence, we increment it at the time we set
 498                  * it by one.
 499                  */
 500                 crypto_inc(drbg->V, drbg_blocklen(drbg));
 501
 502                 ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
 503                                              drbg_keylen(drbg));
 504                 if (ret)
 505                         goto out;
 506         }
 507
 508         /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
 509         if (seed) {
 510                 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
 511                 if (ret)
 512                         goto out;
 513         }
 514
 515         ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
 516                                  temp, drbg_statelen(drbg));
 517         if (ret)
 518                 return ret;
 519
 520         /* 10.2.1.2 step 5 */
 521         ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
 522                                      drbg_keylen(drbg));
 523         if (ret)
 524                 goto out;
 525         /* 10.2.1.2 step 6 */
 526         memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
 527         /* See above: increment counter by one to compensate timing of CTR op */
 528         crypto_inc(drbg->V, drbg_blocklen(drbg));
 529         ret = 0;
 530
 531 out:
 532         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 533         if (2 != reseed)
 534                 memset(df_data, 0, drbg_statelen(drbg));
 535         return ret;
 536 }
 537
 538 /*
 539  * scratchpad use: drbg_ctr_update is called independently from
 540  * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
 541  */
 542 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
 543 static int drbg_ctr_generate(struct drbg_state *drbg,
 544                              unsigned char *buf, unsigned int buflen,
 545                              struct list_head *addtl)
 546 {
 547         int ret;
 548         int len = min_t(int, buflen, INT_MAX);
 549
 550         /* 10.2.1.5.2 step 2 */
 551         if (addtl && !list_empty(addtl)) {
 552                 ret = drbg_ctr_update(drbg, addtl, 2);
 553                 if (ret)
 554                         return 0;
 555         }
 556
 557         /* 10.2.1.5.2 step 4.1 */
 558         ret = drbg_kcapi_sym_ctr(drbg, drbg->ctr_null_value, DRBG_CTR_NULL_LEN,
 559                                  buf, len);
 560         if (ret)
 561                 return ret;
 562
 563         /* 10.2.1.5.2 step 6 */
 564         ret = drbg_ctr_update(drbg, NULL, 3);
 565         if (ret)
 566                 len = ret;
 567
 568         return len;
 569 }
 570
 571 static const struct drbg_state_ops drbg_ctr_ops = {
 572         .update         = drbg_ctr_update,
 573         .generate       = drbg_ctr_generate,
 574         .crypto_init    = drbg_init_sym_kernel,
 575         .crypto_fini    = drbg_fini_sym_kernel,
 576 };
 577 #endif /* CONFIG_CRYPTO_DRBG_CTR */
 578
 579 /******************************************************************
 580  * HMAC DRBG callback functions
 581  ******************************************************************/
 582
 583 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
 584 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
 585                            const struct list_head *in);
 586 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
 587                                   const unsigned char *key);
 588 static int drbg_init_hash_kernel(struct drbg_state *drbg);
 589 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
 590 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
 591
 592 #ifdef CONFIG_CRYPTO_DRBG_HMAC
 593 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
 594 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
 595 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
 596 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
 597 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
 598 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
 599 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
 600 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
 601 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
 602
 603 /* update function of HMAC DRBG as defined in 10.1.2.2 */
 604 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
 605                             int reseed)
 606 {
 607         int ret = -EFAULT;
 608         int i = 0;
 609         struct drbg_string seed1, seed2, vdata;
 610         LIST_HEAD(seedlist);
 611         LIST_HEAD(vdatalist);
 612
 613         if (!reseed) {
 614                 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
 615                 memset(drbg->V, 1, drbg_statelen(drbg));
 616                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
 617         }
 618
 619         drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
 620         list_add_tail(&seed1.list, &seedlist);
 621         /* buffer of seed2 will be filled in for loop below with one byte */
 622         drbg_string_fill(&seed2, NULL, 1);
 623         list_add_tail(&seed2.list, &seedlist);
 624         /* input data of seed is allowed to be NULL at this point */
 625         if (seed)
 626                 list_splice_tail(seed, &seedlist);
 627
 628         drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
 629         list_add_tail(&vdata.list, &vdatalist);
 630         for (i = 2; 0 < i; i--) {
 631                 /* first round uses 0x0, second 0x1 */
 632                 unsigned char prefix = DRBG_PREFIX0;
 633                 if (1 == i)
 634                         prefix = DRBG_PREFIX1;
 635                 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
 636                 seed2.buf = &prefix;
 637                 ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
 638                 if (ret)
 639                         return ret;
 640                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
 641
 642                 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
 643                 ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
 644                 if (ret)
 645                         return ret;
 646
 647                 /* 10.1.2.2 step 3 */
 648                 if (!seed)
 649                         return ret;
 650         }
 651
 652         return 0;
 653 }
 654
 655 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
 656 static int drbg_hmac_generate(struct drbg_state *drbg,
 657                               unsigned char *buf,
 658                               unsigned int buflen,
 659                               struct list_head *addtl)
 660 {
 661         int len = 0;
 662         int ret = 0;
 663         struct drbg_string data;
 664         LIST_HEAD(datalist);
 665
 666         /* 10.1.2.5 step 2 */
 667         if (addtl && !list_empty(addtl)) {
 668                 ret = drbg_hmac_update(drbg, addtl, 1);
 669                 if (ret)
 670                         return ret;
 671         }
 672
 673         drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
 674         list_add_tail(&data.list, &datalist);
 675         while (len < buflen) {
 676                 unsigned int outlen = 0;
 677                 /* 10.1.2.5 step 4.1 */
 678                 ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
 679                 if (ret)
 680                         return ret;
 681                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 682                           drbg_blocklen(drbg) : (buflen - len);
 683
 684                 /* 10.1.2.5 step 4.2 */
 685                 memcpy(buf + len, drbg->V, outlen);
 686                 len += outlen;
 687         }
 688
 689         /* 10.1.2.5 step 6 */
 690         if (addtl && !list_empty(addtl))
 691                 ret = drbg_hmac_update(drbg, addtl, 1);
 692         else
 693                 ret = drbg_hmac_update(drbg, NULL, 1);
 694         if (ret)
 695                 return ret;
 696
 697         return len;
 698 }
 699
 700 static const struct drbg_state_ops drbg_hmac_ops = {
 701         .update         = drbg_hmac_update,
 702         .generate       = drbg_hmac_generate,
 703         .crypto_init    = drbg_init_hash_kernel,
 704         .crypto_fini    = drbg_fini_hash_kernel,
 705 };
 706 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
 707
 708 /******************************************************************
 709  * Hash DRBG callback functions
 710  ******************************************************************/
 711
 712 #ifdef CONFIG_CRYPTO_DRBG_HASH
 713 #define CRYPTO_DRBG_HASH_STRING "HASH "
 714 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
 715 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
 716 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
 717 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
 718 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
 719 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
 720 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
 721 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
 722
 723 /*
 724  * Increment buffer
 725  *
 726  * @dst buffer to increment
 727  * @add value to add
 728  */
 729 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
 730                                 const unsigned char *add, size_t addlen)
 731 {
 732         /* implied: dstlen > addlen */
 733         unsigned char *dstptr;
 734         const unsigned char *addptr;
 735         unsigned int remainder = 0;
 736         size_t len = addlen;
 737
 738         dstptr = dst + (dstlen-1);
 739         addptr = add + (addlen-1);
 740         while (len) {
 741                 remainder += *dstptr + *addptr;
 742                 *dstptr = remainder & 0xff;
 743                 remainder >>= 8;
 744                 len--; dstptr--; addptr--;
 745         }
 746         len = dstlen - addlen;
 747         while (len && remainder > 0) {
 748                 remainder = *dstptr + 1;
 749                 *dstptr = remainder & 0xff;
 750                 remainder >>= 8;
 751                 len--; dstptr--;
 752         }
 753 }
 754
 755 /*
 756  * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
 757  * interlinked, the scratchpad is used as follows:
 758  * drbg_hash_update
 759  *      start: drbg->scratchpad
 760  *      length: drbg_statelen(drbg)
 761  * drbg_hash_df:
 762  *      start: drbg->scratchpad + drbg_statelen(drbg)
 763  *      length: drbg_blocklen(drbg)
 764  *
 765  * drbg_hash_process_addtl uses the scratchpad, but fully completes
 766  * before either of the functions mentioned before are invoked. Therefore,
 767  * drbg_hash_process_addtl does not need to be specifically considered.
 768  */
 769
 770 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
 771 static int drbg_hash_df(struct drbg_state *drbg,
 772                         unsigned char *outval, size_t outlen,
 773                         struct list_head *entropylist)
 774 {
 775         int ret = 0;
 776         size_t len = 0;
 777         unsigned char input[5];
 778         unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
 779         struct drbg_string data;
 780
 781         /* 10.4.1 step 3 */
 782         input[0] = 1;
 783         drbg_cpu_to_be32((outlen * 8), &input[1]);
 784
 785         /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
 786         drbg_string_fill(&data, input, 5);
 787         list_add(&data.list, entropylist);
 788
 789         /* 10.4.1 step 4 */
 790         while (len < outlen) {
 791                 short blocklen = 0;
 792                 /* 10.4.1 step 4.1 */
 793                 ret = drbg_kcapi_hash(drbg, tmp, entropylist);
 794                 if (ret)
 795                         goto out;
 796                 /* 10.4.1 step 4.2 */
 797                 input[0]++;
 798                 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
 799                             drbg_blocklen(drbg) : (outlen - len);
 800                 memcpy(outval + len, tmp, blocklen);
 801                 len += blocklen;
 802         }
 803
 804 out:
 805         memset(tmp, 0, drbg_blocklen(drbg));
 806         return ret;
 807 }
 808
 809 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
 810 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
 811                             int reseed)
 812 {
 813         int ret = 0;
 814         struct drbg_string data1, data2;
 815         LIST_HEAD(datalist);
 816         LIST_HEAD(datalist2);
 817         unsigned char *V = drbg->scratchpad;
 818         unsigned char prefix = DRBG_PREFIX1;
 819
 820         if (!seed)
 821                 return -EINVAL;
 822
 823         if (reseed) {
 824                 /* 10.1.1.3 step 1 */
 825                 memcpy(V, drbg->V, drbg_statelen(drbg));
 826                 drbg_string_fill(&data1, &prefix, 1);
 827                 list_add_tail(&data1.list, &datalist);
 828                 drbg_string_fill(&data2, V, drbg_statelen(drbg));
 829                 list_add_tail(&data2.list, &datalist);
 830         }
 831         list_splice_tail(seed, &datalist);
 832
 833         /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
 834         ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
 835         if (ret)
 836                 goto out;
 837
 838         /* 10.1.1.2 / 10.1.1.3 step 4  */
 839         prefix = DRBG_PREFIX0;
 840         drbg_string_fill(&data1, &prefix, 1);
 841         list_add_tail(&data1.list, &datalist2);
 842         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 843         list_add_tail(&data2.list, &datalist2);
 844         /* 10.1.1.2 / 10.1.1.3 step 4 */
 845         ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
 846
 847 out:
 848         memset(drbg->scratchpad, 0, drbg_statelen(drbg));
 849         return ret;
 850 }
 851
 852 /* processing of additional information string for Hash DRBG */
 853 static int drbg_hash_process_addtl(struct drbg_state *drbg,
 854                                    struct list_head *addtl)
 855 {
 856         int ret = 0;
 857         struct drbg_string data1, data2;
 858         LIST_HEAD(datalist);
 859         unsigned char prefix = DRBG_PREFIX2;
 860
 861         /* 10.1.1.4 step 2 */
 862         if (!addtl || list_empty(addtl))
 863                 return 0;
 864
 865         /* 10.1.1.4 step 2a */
 866         drbg_string_fill(&data1, &prefix, 1);
 867         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 868         list_add_tail(&data1.list, &datalist);
 869         list_add_tail(&data2.list, &datalist);
 870         list_splice_tail(addtl, &datalist);
 871         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
 872         if (ret)
 873                 goto out;
 874
 875         /* 10.1.1.4 step 2b */
 876         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 877                      drbg->scratchpad, drbg_blocklen(drbg));
 878
 879 out:
 880         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 881         return ret;
 882 }
 883
 884 /* Hashgen defined in 10.1.1.4 */
 885 static int drbg_hash_hashgen(struct drbg_state *drbg,
 886                              unsigned char *buf,
 887                              unsigned int buflen)
 888 {
 889         int len = 0;
 890         int ret = 0;
 891         unsigned char *src = drbg->scratchpad;
 892         unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
 893         struct drbg_string data;
 894         LIST_HEAD(datalist);
 895
 896         /* 10.1.1.4 step hashgen 2 */
 897         memcpy(src, drbg->V, drbg_statelen(drbg));
 898
 899         drbg_string_fill(&data, src, drbg_statelen(drbg));
 900         list_add_tail(&data.list, &datalist);
 901         while (len < buflen) {
 902                 unsigned int outlen = 0;
 903                 /* 10.1.1.4 step hashgen 4.1 */
 904                 ret = drbg_kcapi_hash(drbg, dst, &datalist);
 905                 if (ret) {
 906                         len = ret;
 907                         goto out;
 908                 }
 909                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 910                           drbg_blocklen(drbg) : (buflen - len);
 911                 /* 10.1.1.4 step hashgen 4.2 */
 912                 memcpy(buf + len, dst, outlen);
 913                 len += outlen;
 914                 /* 10.1.1.4 hashgen step 4.3 */
 915                 if (len < buflen)
 916                         crypto_inc(src, drbg_statelen(drbg));
 917         }
 918
 919 out:
 920         memset(drbg->scratchpad, 0,
 921                (drbg_statelen(drbg) + drbg_blocklen(drbg)));
 922         return len;
 923 }
 924
 925 /* generate function for Hash DRBG as defined in  10.1.1.4 */
 926 static int drbg_hash_generate(struct drbg_state *drbg,
 927                               unsigned char *buf, unsigned int buflen,
 928                               struct list_head *addtl)
 929 {
 930         int len = 0;
 931         int ret = 0;
 932         union {
 933                 unsigned char req[8];
 934                 __be64 req_int;
 935         } u;
 936         unsigned char prefix = DRBG_PREFIX3;
 937         struct drbg_string data1, data2;
 938         LIST_HEAD(datalist);
 939
 940         /* 10.1.1.4 step 2 */
 941         ret = drbg_hash_process_addtl(drbg, addtl);
 942         if (ret)
 943                 return ret;
 944         /* 10.1.1.4 step 3 */
 945         len = drbg_hash_hashgen(drbg, buf, buflen);
 946
 947         /* this is the value H as documented in 10.1.1.4 */
 948         /* 10.1.1.4 step 4 */
 949         drbg_string_fill(&data1, &prefix, 1);
 950         list_add_tail(&data1.list, &datalist);
 951         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 952         list_add_tail(&data2.list, &datalist);
 953         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
 954         if (ret) {
 955                 len = ret;
 956                 goto out;
 957         }
 958
 959         /* 10.1.1.4 step 5 */
 960         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 961                      drbg->scratchpad, drbg_blocklen(drbg));
 962         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 963                      drbg->C, drbg_statelen(drbg));
 964         u.req_int = cpu_to_be64(drbg->reseed_ctr);
 965         drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
 966
 967 out:
 968         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 969         return len;
 970 }
 971
 972 /*
 973  * scratchpad usage: as update and generate are used isolated, both
 974  * can use the scratchpad
 975  */
 976 static const struct drbg_state_ops drbg_hash_ops = {
 977         .update         = drbg_hash_update,
 978         .generate       = drbg_hash_generate,
 979         .crypto_init    = drbg_init_hash_kernel,
 980         .crypto_fini    = drbg_fini_hash_kernel,
 981 };
 982 #endif /* CONFIG_CRYPTO_DRBG_HASH */
 983
 984 /******************************************************************
 985  * Functions common for DRBG implementations
 986  ******************************************************************/
 987
 988 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
 989                               int reseed)
 990 {
 991         int ret = drbg->d_ops->update(drbg, seed, reseed);
 992
 993         if (ret)
 994                 return ret;
 995
 996         drbg->seeded = true;
 997         /* 10.1.1.2 / 10.1.1.3 step 5 */
 998         drbg->reseed_ctr = 1;
 999
1000         return ret;
1001 }
1002
1003 static void drbg_async_seed(struct work_struct *work)
1004 {
1005         struct drbg_string data;
1006         LIST_HEAD(seedlist);
1007         struct drbg_state *drbg = container_of(work, struct drbg_state,
1008                                                seed_work);
1009         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1010         unsigned char entropy[32];
1011
1012         BUG_ON(!entropylen);
1013         BUG_ON(entropylen > sizeof(entropy));
1014         get_random_bytes(entropy, entropylen);
1015
1016         drbg_string_fill(&data, entropy, entropylen);
1017         list_add_tail(&data.list, &seedlist);
1018
1019         mutex_lock(&drbg->drbg_mutex);
1020
1021         /* If nonblocking pool is initialized, deactivate Jitter RNG */
1022         crypto_free_rng(drbg->jent);
1023         drbg->jent = NULL;
1024
1025         /* Set seeded to false so that if __drbg_seed fails the
1026          * next generate call will trigger a reseed.
1027          */
1028         drbg->seeded = false;
1029
1030         __drbg_seed(drbg, &seedlist, true);
1031
1032         if (drbg->seeded)
1033                 drbg->reseed_threshold = drbg_max_requests(drbg);
1034
1035         mutex_unlock(&drbg->drbg_mutex);
1036
1037         memzero_explicit(entropy, entropylen);
1038 }
1039
1040 /*
1041  * Seeding or reseeding of the DRBG
1042  *
1043  * @drbg: DRBG state struct
1044  * @pers: personalization / additional information buffer
1045  * @reseed: 0 for initial seed process, 1 for reseeding
1046  *
1047  * return:
1048  *      0 on success
1049  *      error value otherwise
1050  */
1051 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1052                      bool reseed)
1053 {
1054         int ret;
1055         unsigned char entropy[((32 + 16) * 2)];
1056         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1057         struct drbg_string data1;
1058         LIST_HEAD(seedlist);
1059
1060         /* 9.1 / 9.2 / 9.3.1 step 3 */
1061         if (pers && pers->len > (drbg_max_addtl(drbg))) {
1062                 pr_devel("DRBG: personalization string too long %zu\n",
1063                          pers->len);
1064                 return -EINVAL;
1065         }
1066
1067         if (list_empty(&drbg->test_data.list)) {
1068                 drbg_string_fill(&data1, drbg->test_data.buf,
1069                                  drbg->test_data.len);
1070                 pr_devel("DRBG: using test entropy\n");
1071         } else {
1072                 /*
1073                  * Gather entropy equal to the security strength of the DRBG.
1074                  * With a derivation function, a nonce is required in addition
1075                  * to the entropy. A nonce must be at least 1/2 of the security
1076                  * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1077                  * of the strength. The consideration of a nonce is only
1078                  * applicable during initial seeding.
1079                  */
1080                 BUG_ON(!entropylen);
1081                 if (!reseed)
1082                         entropylen = ((entropylen + 1) / 2) * 3;
1083                 BUG_ON((entropylen * 2) > sizeof(entropy));
1084
1085                 /* Get seed from in-kernel /dev/urandom */
1086                 get_random_bytes(entropy, entropylen);
1087
1088                 if (!drbg->jent) {
1089                         drbg_string_fill(&data1, entropy, entropylen);
1090                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1091                                  entropylen);
1092                 } else {
1093                         /* Get seed from Jitter RNG */
1094                         ret = crypto_rng_get_bytes(drbg->jent,
1095                                                    entropy + entropylen,
1096                                                    entropylen);
1097                         if (ret) {
1098                                 pr_devel("DRBG: jent failed with %d\n", ret);
1099                                 return ret;
1100                         }
1101
1102                         drbg_string_fill(&data1, entropy, entropylen * 2);
1103                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1104                                  entropylen * 2);
1105                 }
1106         }
1107         list_add_tail(&data1.list, &seedlist);
1108
1109         /*
1110          * concatenation of entropy with personalization str / addtl input)
1111          * the variable pers is directly handed in by the caller, so check its
1112          * contents whether it is appropriate
1113          */
1114         if (pers && pers->buf && 0 < pers->len) {
1115                 list_add_tail(&pers->list, &seedlist);
1116                 pr_devel("DRBG: using personalization string\n");
1117         }
1118
1119         if (!reseed) {
1120                 memset(drbg->V, 0, drbg_statelen(drbg));
1121                 memset(drbg->C, 0, drbg_statelen(drbg));
1122         }
1123
1124         ret = __drbg_seed(drbg, &seedlist, reseed);
1125
1126         memzero_explicit(entropy, entropylen * 2);
1127
1128         return ret;
1129 }
1130
1131 /* Free all substructures in a DRBG state without the DRBG state structure */
1132 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1133 {
1134         if (!drbg)
1135                 return;
1136         kzfree(drbg->V);
1137         drbg->Vbuf = NULL;
1138         kzfree(drbg->C);
1139         drbg->Cbuf = NULL;
1140         kzfree(drbg->scratchpadbuf);
1141         drbg->scratchpadbuf = NULL;
1142         drbg->reseed_ctr = 0;
1143         drbg->d_ops = NULL;
1144         drbg->core = NULL;
1145 }
1146
1147 /*
1148  * Allocate all sub-structures for a DRBG state.
1149  * The DRBG state structure must already be allocated.
1150  */
1151 static inline int drbg_alloc_state(struct drbg_state *drbg)
1152 {
1153         int ret = -ENOMEM;
1154         unsigned int sb_size = 0;
1155
1156         switch (drbg->core->flags & DRBG_TYPE_MASK) {
1157 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1158         case DRBG_HMAC:
1159                 drbg->d_ops = &drbg_hmac_ops;
1160                 break;
1161 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1162 #ifdef CONFIG_CRYPTO_DRBG_HASH
1163         case DRBG_HASH:
1164                 drbg->d_ops = &drbg_hash_ops;
1165                 break;
1166 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1167 #ifdef CONFIG_CRYPTO_DRBG_CTR
1168         case DRBG_CTR:
1169                 drbg->d_ops = &drbg_ctr_ops;
1170                 break;
1171 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1172         default:
1173                 ret = -EOPNOTSUPP;
1174                 goto err;
1175         }
1176
1177         ret = drbg->d_ops->crypto_init(drbg);
1178         if (ret < 0)
1179                 goto err;
1180
1181         drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1182         if (!drbg->Vbuf) {
1183                 ret = -ENOMEM;
1184                 goto fini;
1185         }
1186         drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
1187         drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1188         if (!drbg->Cbuf) {
1189                 ret = -ENOMEM;
1190                 goto fini;
1191         }
1192         drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);
1193         /* scratchpad is only generated for CTR and Hash */
1194         if (drbg->core->flags & DRBG_HMAC)
1195                 sb_size = 0;
1196         else if (drbg->core->flags & DRBG_CTR)
1197                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1198                           drbg_statelen(drbg) + /* df_data */
1199                           drbg_blocklen(drbg) + /* pad */
1200                           drbg_blocklen(drbg) + /* iv */
1201                           drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1202         else
1203                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1204
1205         if (0 < sb_size) {
1206                 drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);
1207                 if (!drbg->scratchpadbuf) {
1208                         ret = -ENOMEM;
1209                         goto fini;
1210                 }
1211                 drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);
1212         }
1213
1214         return 0;
1215
1216 fini:
1217         drbg->d_ops->crypto_fini(drbg);
1218 err:
1219         drbg_dealloc_state(drbg);
1220         return ret;
1221 }
1222
1223 /*************************************************************************
1224  * DRBG interface functions
1225  *************************************************************************/
1226
1227 /*
1228  * DRBG generate function as required by SP800-90A - this function
1229  * generates random numbers
1230  *
1231  * @drbg DRBG state handle
1232  * @buf Buffer where to store the random numbers -- the buffer must already
1233  *      be pre-allocated by caller
1234  * @buflen Length of output buffer - this value defines the number of random
1235  *         bytes pulled from DRBG
1236  * @addtl Additional input that is mixed into state, may be NULL -- note
1237  *        the entropy is pulled by the DRBG internally unconditionally
1238  *        as defined in SP800-90A. The additional input is mixed into
1239  *        the state in addition to the pulled entropy.
1240  *
1241  * return: 0 when all bytes are generated; < 0 in case of an error
1242  */
1243 static int drbg_generate(struct drbg_state *drbg,
1244                          unsigned char *buf, unsigned int buflen,
1245                          struct drbg_string *addtl)
1246 {
1247         int len = 0;
1248         LIST_HEAD(addtllist);
1249
1250         if (!drbg->core) {
1251                 pr_devel("DRBG: not yet seeded\n");
1252                 return -EINVAL;
1253         }
1254         if (0 == buflen || !buf) {
1255                 pr_devel("DRBG: no output buffer provided\n");
1256                 return -EINVAL;
1257         }
1258         if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1259                 pr_devel("DRBG: wrong format of additional information\n");
1260                 return -EINVAL;
1261         }
1262
1263         /* 9.3.1 step 2 */
1264         len = -EINVAL;
1265         if (buflen > (drbg_max_request_bytes(drbg))) {
1266                 pr_devel("DRBG: requested random numbers too large %u\n",
1267                          buflen);
1268                 goto err;
1269         }
1270
1271         /* 9.3.1 step 3 is implicit with the chosen DRBG */
1272
1273         /* 9.3.1 step 4 */
1274         if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1275                 pr_devel("DRBG: additional information string too long %zu\n",
1276                          addtl->len);
1277                 goto err;
1278         }
1279         /* 9.3.1 step 5 is implicit with the chosen DRBG */
1280
1281         /*
1282          * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1283          * here. The spec is a bit convoluted here, we make it simpler.
1284          */
1285         if (drbg->reseed_threshold < drbg->reseed_ctr)
1286                 drbg->seeded = false;
1287
1288         if (drbg->pr || !drbg->seeded) {
1289                 pr_devel("DRBG: reseeding before generation (prediction "
1290                          "resistance: %s, state %s)\n",
1291                          drbg->pr ? "true" : "false",
1292                          drbg->seeded ? "seeded" : "unseeded");
1293                 /* 9.3.1 steps 7.1 through 7.3 */
1294                 len = drbg_seed(drbg, addtl, true);
1295                 if (len)
1296                         goto err;
1297                 /* 9.3.1 step 7.4 */
1298                 addtl = NULL;
1299         }
1300
1301         if (addtl && 0 < addtl->len)
1302                 list_add_tail(&addtl->list, &addtllist);
1303         /* 9.3.1 step 8 and 10 */
1304         len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1305
1306         /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1307         drbg->reseed_ctr++;
1308         if (0 >= len)
1309                 goto err;
1310
1311         /*
1312          * Section 11.3.3 requires to re-perform self tests after some
1313          * generated random numbers. The chosen value after which self
1314          * test is performed is arbitrary, but it should be reasonable.
1315          * However, we do not perform the self tests because of the following
1316          * reasons: it is mathematically impossible that the initial self tests
1317          * were successfully and the following are not. If the initial would
1318          * pass and the following would not, the kernel integrity is violated.
1319          * In this case, the entire kernel operation is questionable and it
1320          * is unlikely that the integrity violation only affects the
1321          * correct operation of the DRBG.
1322          *
1323          * Albeit the following code is commented out, it is provided in
1324          * case somebody has a need to implement the test of 11.3.3.
1325          */
1326 #if 0
1327         if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1328                 int err = 0;
1329                 pr_devel("DRBG: start to perform self test\n");
1330                 if (drbg->core->flags & DRBG_HMAC)
1331                         err = alg_test("drbg_pr_hmac_sha256",
1332                                        "drbg_pr_hmac_sha256", 0, 0);
1333                 else if (drbg->core->flags & DRBG_CTR)
1334                         err = alg_test("drbg_pr_ctr_aes128",
1335                                        "drbg_pr_ctr_aes128", 0, 0);
1336                 else
1337                         err = alg_test("drbg_pr_sha256",
1338                                        "drbg_pr_sha256", 0, 0);
1339                 if (err) {
1340                         pr_err("DRBG: periodical self test failed\n");
1341                         /*
1342                          * uninstantiate implies that from now on, only errors
1343                          * are returned when reusing this DRBG cipher handle
1344                          */
1345                         drbg_uninstantiate(drbg);
1346                         return 0;
1347                 } else {
1348                         pr_devel("DRBG: self test successful\n");
1349                 }
1350         }
1351 #endif
1352
1353         /*
1354          * All operations were successful, return 0 as mandated by
1355          * the kernel crypto API interface.
1356          */
1357         len = 0;
1358 err:
1359         return len;
1360 }
1361
1362 /*
1363  * Wrapper around drbg_generate which can pull arbitrary long strings
1364  * from the DRBG without hitting the maximum request limitation.
1365  *
1366  * Parameters: see drbg_generate
1367  * Return codes: see drbg_generate -- if one drbg_generate request fails,
1368  *               the entire drbg_generate_long request fails
1369  */
1370 static int drbg_generate_long(struct drbg_state *drbg,
1371                               unsigned char *buf, unsigned int buflen,
1372                               struct drbg_string *addtl)
1373 {
1374         unsigned int len = 0;
1375         unsigned int slice = 0;
1376         do {
1377                 int err = 0;
1378                 unsigned int chunk = 0;
1379                 slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1380                 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1381                 mutex_lock(&drbg->drbg_mutex);
1382                 err = drbg_generate(drbg, buf + len, chunk, addtl);
1383                 mutex_unlock(&drbg->drbg_mutex);
1384                 if (0 > err)
1385                         return err;
1386                 len += chunk;
1387         } while (slice > 0 && (len < buflen));
1388         return 0;
1389 }
1390
1391 static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
1392 {
1393         struct drbg_state *drbg = container_of(rdy, struct drbg_state,
1394                                                random_ready);
1395
1396         schedule_work(&drbg->seed_work);
1397 }
1398
1399 static int drbg_prepare_hrng(struct drbg_state *drbg)
1400 {
1401         int err;
1402
1403         /* We do not need an HRNG in test mode. */
1404         if (list_empty(&drbg->test_data.list))
1405                 return 0;
1406
1407         INIT_WORK(&drbg->seed_work, drbg_async_seed);
1408
1409         drbg->random_ready.owner = THIS_MODULE;
1410         drbg->random_ready.func = drbg_schedule_async_seed;
1411
1412         err = add_random_ready_callback(&drbg->random_ready);
1413
1414         switch (err) {
1415         case 0:
1416                 break;
1417
1418         case -EALREADY:
1419                 err = 0;
1420                 /* fall through */
1421
1422         default:
1423                 drbg->random_ready.func = NULL;
1424                 return err;
1425         }
1426
1427         drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
1428
1429         /*
1430          * Require frequent reseeds until the seed source is fully
1431          * initialized.
1432          */
1433         drbg->reseed_threshold = 50;
1434
1435         return err;
1436 }
1437
1438 /*
1439  * DRBG instantiation function as required by SP800-90A - this function
1440  * sets up the DRBG handle, performs the initial seeding and all sanity
1441  * checks required by SP800-90A
1442  *
1443  * @drbg memory of state -- if NULL, new memory is allocated
1444  * @pers Personalization string that is mixed into state, may be NULL -- note
1445  *       the entropy is pulled by the DRBG internally unconditionally
1446  *       as defined in SP800-90A. The additional input is mixed into
1447  *       the state in addition to the pulled entropy.
1448  * @coreref reference to core
1449  * @pr prediction resistance enabled
1450  *
1451  * return
1452  *      0 on success
1453  *      error value otherwise
1454  */
1455 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1456                             int coreref, bool pr)
1457 {
1458         int ret;
1459         bool reseed = true;
1460
1461         pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1462                  "%s\n", coreref, pr ? "enabled" : "disabled");
1463         mutex_lock(&drbg->drbg_mutex);
1464
1465         /* 9.1 step 1 is implicit with the selected DRBG type */
1466
1467         /*
1468          * 9.1 step 2 is implicit as caller can select prediction resistance
1469          * and the flag is copied into drbg->flags --
1470          * all DRBG types support prediction resistance
1471          */
1472
1473         /* 9.1 step 4 is implicit in  drbg_sec_strength */
1474
1475         if (!drbg->core) {
1476                 drbg->core = &drbg_cores[coreref];
1477                 drbg->pr = pr;
1478                 drbg->seeded = false;
1479                 drbg->reseed_threshold = drbg_max_requests(drbg);
1480
1481                 ret = drbg_alloc_state(drbg);
1482                 if (ret)
1483                         goto unlock;
1484
1485                 ret = drbg_prepare_hrng(drbg);
1486                 if (ret)
1487                         goto free_everything;
1488
1489                 if (IS_ERR(drbg->jent)) {
1490                         ret = PTR_ERR(drbg->jent);
1491                         drbg->jent = NULL;
1492                         if (fips_enabled || ret != -ENOENT)
1493                                 goto free_everything;
1494                         pr_info("DRBG: Continuing without Jitter RNG\n");
1495                 }
1496
1497                 reseed = false;
1498         }
1499
1500         ret = drbg_seed(drbg, pers, reseed);
1501
1502         if (ret && !reseed)
1503                 goto free_everything;
1504
1505         mutex_unlock(&drbg->drbg_mutex);
1506         return ret;
1507
1508 unlock:
1509         mutex_unlock(&drbg->drbg_mutex);
1510         return ret;
1511
1512 free_everything:
1513         mutex_unlock(&drbg->drbg_mutex);
1514         drbg_uninstantiate(drbg);
1515         return ret;
1516 }
1517
1518 /*
1519  * DRBG uninstantiate function as required by SP800-90A - this function
1520  * frees all buffers and the DRBG handle
1521  *
1522  * @drbg DRBG state handle
1523  *
1524  * return
1525  *      0 on success
1526  */
1527 static int drbg_uninstantiate(struct drbg_state *drbg)
1528 {
1529         if (drbg->random_ready.func) {
1530                 del_random_ready_callback(&drbg->random_ready);
1531                 cancel_work_sync(&drbg->seed_work);
1532                 crypto_free_rng(drbg->jent);
1533                 drbg->jent = NULL;
1534         }
1535
1536         if (drbg->d_ops)
1537                 drbg->d_ops->crypto_fini(drbg);
1538         drbg_dealloc_state(drbg);
1539         /* no scrubbing of test_data -- this shall survive an uninstantiate */
1540         return 0;
1541 }
1542
1543 /*
1544  * Helper function for setting the test data in the DRBG
1545  *
1546  * @drbg DRBG state handle
1547  * @data test data
1548  * @len test data length
1549  */
1550 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
1551                                    const u8 *data, unsigned int len)
1552 {
1553         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1554
1555         mutex_lock(&drbg->drbg_mutex);
1556         drbg_string_fill(&drbg->test_data, data, len);
1557         mutex_unlock(&drbg->drbg_mutex);
1558 }
1559
1560 /***************************************************************
1561  * Kernel crypto API cipher invocations requested by DRBG
1562  ***************************************************************/
1563
1564 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1565 struct sdesc {
1566         struct shash_desc shash;
1567         char ctx[];
1568 };
1569
1570 static int drbg_init_hash_kernel(struct drbg_state *drbg)
1571 {
1572         struct sdesc *sdesc;
1573         struct crypto_shash *tfm;
1574
1575         tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1576         if (IS_ERR(tfm)) {
1577                 pr_info("DRBG: could not allocate digest TFM handle: %s\n",
1578                                 drbg->core->backend_cra_name);
1579                 return PTR_ERR(tfm);
1580         }
1581         BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1582         sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1583                         GFP_KERNEL);
1584         if (!sdesc) {
1585                 crypto_free_shash(tfm);
1586                 return -ENOMEM;
1587         }
1588
1589         sdesc->shash.tfm = tfm;
1590         sdesc->shash.flags = 0;
1591         drbg->priv_data = sdesc;
1592
1593         return crypto_shash_alignmask(tfm);
1594 }
1595
1596 static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1597 {
1598         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1599         if (sdesc) {
1600                 crypto_free_shash(sdesc->shash.tfm);
1601                 kzfree(sdesc);
1602         }
1603         drbg->priv_data = NULL;
1604         return 0;
1605 }
1606
1607 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
1608                                   const unsigned char *key)
1609 {
1610         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1611
1612         crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
1613 }
1614
1615 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
1616                            const struct list_head *in)
1617 {
1618         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1619         struct drbg_string *input = NULL;
1620
1621         crypto_shash_init(&sdesc->shash);
1622         list_for_each_entry(input, in, list)
1623                 crypto_shash_update(&sdesc->shash, input->buf, input->len);
1624         return crypto_shash_final(&sdesc->shash, outval);
1625 }
1626 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1627
1628 #ifdef CONFIG_CRYPTO_DRBG_CTR
1629 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1630 {
1631         struct crypto_cipher *tfm =
1632                 (struct crypto_cipher *)drbg->priv_data;
1633         if (tfm)
1634                 crypto_free_cipher(tfm);
1635         drbg->priv_data = NULL;
1636
1637         if (drbg->ctr_handle)
1638                 crypto_free_skcipher(drbg->ctr_handle);
1639         drbg->ctr_handle = NULL;
1640
1641         if (drbg->ctr_req)
1642                 skcipher_request_free(drbg->ctr_req);
1643         drbg->ctr_req = NULL;
1644
1645         kfree(drbg->ctr_null_value_buf);
1646         drbg->ctr_null_value = NULL;
1647
1648         kfree(drbg->outscratchpadbuf);
1649         drbg->outscratchpadbuf = NULL;
1650
1651         return 0;
1652 }
1653
1654 static void drbg_skcipher_cb(struct crypto_async_request *req, int error)
1655 {
1656         struct drbg_state *drbg = req->data;
1657
1658         if (error == -EINPROGRESS)
1659                 return;
1660         drbg->ctr_async_err = error;
1661         complete(&drbg->ctr_completion);
1662 }
1663
1664 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1665 {
1666         struct crypto_cipher *tfm;
1667         struct crypto_skcipher *sk_tfm;
1668         struct skcipher_request *req;
1669         unsigned int alignmask;
1670         char ctr_name[CRYPTO_MAX_ALG_NAME];
1671
1672         tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1673         if (IS_ERR(tfm)) {
1674                 pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1675                                 drbg->core->backend_cra_name);
1676                 return PTR_ERR(tfm);
1677         }
1678         BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1679         drbg->priv_data = tfm;
1680
1681         if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1682             drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1683                 drbg_fini_sym_kernel(drbg);
1684                 return -EINVAL;
1685         }
1686         sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1687         if (IS_ERR(sk_tfm)) {
1688                 pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1689                                 ctr_name);
1690                 drbg_fini_sym_kernel(drbg);
1691                 return PTR_ERR(sk_tfm);
1692         }
1693         drbg->ctr_handle = sk_tfm;
1694
1695         req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1696         if (!req) {
1697                 pr_info("DRBG: could not allocate request queue\n");
1698                 drbg_fini_sym_kernel(drbg);
1699                 return -ENOMEM;
1700         }
1701         drbg->ctr_req = req;
1702         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
1703                                         drbg_skcipher_cb, drbg);
1704
1705         alignmask = crypto_skcipher_alignmask(sk_tfm);
1706         drbg->ctr_null_value_buf = kzalloc(DRBG_CTR_NULL_LEN + alignmask,
1707                                            GFP_KERNEL);
1708         if (!drbg->ctr_null_value_buf) {
1709                 drbg_fini_sym_kernel(drbg);
1710                 return -ENOMEM;
1711         }
1712         drbg->ctr_null_value = (u8 *)PTR_ALIGN(drbg->ctr_null_value_buf,
1713                                                alignmask + 1);
1714
1715         drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
1716                                          GFP_KERNEL);
1717         if (!drbg->outscratchpadbuf) {
1718                 drbg_fini_sym_kernel(drbg);
1719                 return -ENOMEM;
1720         }
1721         drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
1722                                               alignmask + 1);
1723
1724         return alignmask;
1725 }
1726
1727 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1728                                  const unsigned char *key)
1729 {
1730         struct crypto_cipher *tfm =
1731                 (struct crypto_cipher *)drbg->priv_data;
1732
1733         crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1734 }
1735
1736 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1737                           const struct drbg_string *in)
1738 {
1739         struct crypto_cipher *tfm =
1740                 (struct crypto_cipher *)drbg->priv_data;
1741
1742         /* there is only component in *in */
1743         BUG_ON(in->len < drbg_blocklen(drbg));
1744         crypto_cipher_encrypt_one(tfm, outval, in->buf);
1745         return 0;
1746 }
1747
1748 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1749                               u8 *inbuf, u32 inlen,
1750                               u8 *outbuf, u32 outlen)
1751 {
1752         struct scatterlist sg_in, sg_out;
1753         int ret;
1754
1755         sg_init_one(&sg_in, inbuf, inlen);
1756         sg_init_one(&sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1757
1758         while (outlen) {
1759                 u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1760
1761                 /* Output buffer may not be valid for SGL, use scratchpad */
1762                 skcipher_request_set_crypt(drbg->ctr_req, &sg_in, &sg_out,
1763                                            cryptlen, drbg->V);
1764                 ret = crypto_skcipher_encrypt(drbg->ctr_req);
1765                 switch (ret) {
1766                 case 0:
1767                         break;
1768                 case -EINPROGRESS:
1769                 case -EBUSY:
1770                         wait_for_completion(&drbg->ctr_completion);
1771                         if (!drbg->ctr_async_err) {
1772                                 reinit_completion(&drbg->ctr_completion);
1773                                 break;
1774                         }
1775                 default:
1776                         goto out;
1777                 }
1778                 init_completion(&drbg->ctr_completion);
1779
1780                 memcpy(outbuf, drbg->outscratchpad, cryptlen);
1781
1782                 outlen -= cryptlen;
1783                 outbuf += cryptlen;
1784         }
1785         ret = 0;
1786
1787 out:
1788         memzero_explicit(drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1789         return ret;
1790 }
1791 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1792
1793 /***************************************************************
1794  * Kernel crypto API interface to register DRBG
1795  ***************************************************************/
1796
1797 /*
1798  * Look up the DRBG flags by given kernel crypto API cra_name
1799  * The code uses the drbg_cores definition to do this
1800  *
1801  * @cra_name kernel crypto API cra_name
1802  * @coreref reference to integer which is filled with the pointer to
1803  *  the applicable core
1804  * @pr reference for setting prediction resistance
1805  *
1806  * return: flags
1807  */
1808 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1809                                          int *coreref, bool *pr)
1810 {
1811         int i = 0;
1812         size_t start = 0;
1813         int len = 0;
1814
1815         *pr = true;
1816         /* disassemble the names */
1817         if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1818                 start = 10;
1819                 *pr = false;
1820         } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1821                 start = 8;
1822         } else {
1823                 return;
1824         }
1825
1826         /* remove the first part */
1827         len = strlen(cra_driver_name) - start;
1828         for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1829                 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1830                             len)) {
1831                         *coreref = i;
1832                         return;
1833                 }
1834         }
1835 }
1836
1837 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1838 {
1839         struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1840
1841         mutex_init(&drbg->drbg_mutex);
1842
1843         return 0;
1844 }
1845
1846 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1847 {
1848         drbg_uninstantiate(crypto_tfm_ctx(tfm));
1849 }
1850
1851 /*
1852  * Generate random numbers invoked by the kernel crypto API:
1853  * The API of the kernel crypto API is extended as follows:
1854  *
1855  * src is additional input supplied to the RNG.
1856  * slen is the length of src.
1857  * dst is the output buffer where random data is to be stored.
1858  * dlen is the length of dst.
1859  */
1860 static int drbg_kcapi_random(struct crypto_rng *tfm,
1861                              const u8 *src, unsigned int slen,
1862                              u8 *dst, unsigned int dlen)
1863 {
1864         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1865         struct drbg_string *addtl = NULL;
1866         struct drbg_string string;
1867
1868         if (slen) {
1869                 /* linked list variable is now local to allow modification */
1870                 drbg_string_fill(&string, src, slen);
1871                 addtl = &string;
1872         }
1873
1874         return drbg_generate_long(drbg, dst, dlen, addtl);
1875 }
1876
1877 /*
1878  * Seed the DRBG invoked by the kernel crypto API
1879  */
1880 static int drbg_kcapi_seed(struct crypto_rng *tfm,
1881                            const u8 *seed, unsigned int slen)
1882 {
1883         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1884         struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1885         bool pr = false;
1886         struct drbg_string string;
1887         struct drbg_string *seed_string = NULL;
1888         int coreref = 0;
1889
1890         drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1891                               &pr);
1892         if (0 < slen) {
1893                 drbg_string_fill(&string, seed, slen);
1894                 seed_string = &string;
1895         }
1896
1897         return drbg_instantiate(drbg, seed_string, coreref, pr);
1898 }
1899
1900 /***************************************************************
1901  * Kernel module: code to load the module
1902  ***************************************************************/
1903
1904 /*
1905  * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1906  * of the error handling.
1907  *
1908  * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1909  * as seed source of get_random_bytes does not fail.
1910  *
1911  * Note 2: There is no sensible way of testing the reseed counter
1912  * enforcement, so skip it.
1913  */
1914 static inline int __init drbg_healthcheck_sanity(void)
1915 {
1916         int len = 0;
1917 #define OUTBUFLEN 16
1918         unsigned char buf[OUTBUFLEN];
1919         struct drbg_state *drbg = NULL;
1920         int ret = -EFAULT;
1921         int rc = -EFAULT;
1922         bool pr = false;
1923         int coreref = 0;
1924         struct drbg_string addtl;
1925         size_t max_addtllen, max_request_bytes;
1926
1927         /* only perform test in FIPS mode */
1928         if (!fips_enabled)
1929                 return 0;
1930
1931 #ifdef CONFIG_CRYPTO_DRBG_CTR
1932         drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1933 #elif defined CONFIG_CRYPTO_DRBG_HASH
1934         drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1935 #else
1936         drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1937 #endif
1938
1939         drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1940         if (!drbg)
1941                 return -ENOMEM;
1942
1943         mutex_init(&drbg->drbg_mutex);
1944         drbg->core = &drbg_cores[coreref];
1945         drbg->reseed_threshold = drbg_max_requests(drbg);
1946
1947         /*
1948          * if the following tests fail, it is likely that there is a buffer
1949          * overflow as buf is much smaller than the requested or provided
1950          * string lengths -- in case the error handling does not succeed
1951          * we may get an OOPS. And we want to get an OOPS as this is a
1952          * grave bug.
1953          */
1954
1955         max_addtllen = drbg_max_addtl(drbg);
1956         max_request_bytes = drbg_max_request_bytes(drbg);
1957         drbg_string_fill(&addtl, buf, max_addtllen + 1);
1958         /* overflow addtllen with additonal info string */
1959         len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1960         BUG_ON(0 < len);
1961         /* overflow max_bits */
1962         len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1963         BUG_ON(0 < len);
1964
1965         /* overflow max addtllen with personalization string */
1966         ret = drbg_seed(drbg, &addtl, false);
1967         BUG_ON(0 == ret);
1968         /* all tests passed */
1969         rc = 0;
1970
1971         pr_devel("DRBG: Sanity tests for failure code paths successfully "
1972                  "completed\n");
1973
1974         kfree(drbg);
1975         return rc;
1976 }
1977
1978 static struct rng_alg drbg_algs[22];
1979
1980 /*
1981  * Fill the array drbg_algs used to register the different DRBGs
1982  * with the kernel crypto API. To fill the array, the information
1983  * from drbg_cores[] is used.
1984  */
1985 static inline void __init drbg_fill_array(struct rng_alg *alg,
1986                                           const struct drbg_core *core, int pr)
1987 {
1988         int pos = 0;
1989         static int priority = 200;
1990
1991         memcpy(alg->base.cra_name, "stdrng", 6);
1992         if (pr) {
1993                 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
1994                 pos = 8;
1995         } else {
1996                 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
1997                 pos = 10;
1998         }
1999         memcpy(alg->base.cra_driver_name + pos, core->cra_name,
2000                strlen(core->cra_name));
2001
2002         alg->base.cra_priority = priority;
2003         priority++;
2004         /*
2005          * If FIPS mode enabled, the selected DRBG shall have the
2006          * highest cra_priority over other stdrng instances to ensure
2007          * it is selected.
2008          */
2009         if (fips_enabled)
2010                 alg->base.cra_priority += 200;
2011
2012         alg->base.cra_ctxsize   = sizeof(struct drbg_state);
2013         alg->base.cra_module    = THIS_MODULE;
2014         alg->base.cra_init      = drbg_kcapi_init;
2015         alg->base.cra_exit      = drbg_kcapi_cleanup;
2016         alg->generate           = drbg_kcapi_random;
2017         alg->seed               = drbg_kcapi_seed;
2018         alg->set_ent            = drbg_kcapi_set_entropy;
2019         alg->seedsize           = 0;
2020 }
2021
2022 static int __init drbg_init(void)
2023 {
2024         unsigned int i = 0; /* pointer to drbg_algs */
2025         unsigned int j = 0; /* pointer to drbg_cores */
2026         int ret;
2027
2028         ret = drbg_healthcheck_sanity();
2029         if (ret)
2030                 return ret;
2031
2032         if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2033                 pr_info("DRBG: Cannot register all DRBG types"
2034                         "(slots needed: %zu, slots available: %zu)\n",
2035                         ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2036                 return -EFAULT;
2037         }
2038
2039         /*
2040          * each DRBG definition can be used with PR and without PR, thus
2041          * we instantiate each DRBG in drbg_cores[] twice.
2042          *
2043          * As the order of placing them into the drbg_algs array matters
2044          * (the later DRBGs receive a higher cra_priority) we register the
2045          * prediction resistance DRBGs first as the should not be too
2046          * interesting.
2047          */
2048         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2049                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2050         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2051                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2052         return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2053 }
2054
2055 static void __exit drbg_exit(void)
2056 {
2057         crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2058 }
2059
2060 module_init(drbg_init);
2061 module_exit(drbg_exit);
2062 #ifndef CRYPTO_DRBG_HASH_STRING
2063 #define CRYPTO_DRBG_HASH_STRING ""
2064 #endif
2065 #ifndef CRYPTO_DRBG_HMAC_STRING
2066 #define CRYPTO_DRBG_HMAC_STRING ""
2067 #endif
2068 #ifndef CRYPTO_DRBG_CTR_STRING
2069 #define CRYPTO_DRBG_CTR_STRING ""
2070 #endif
2071 MODULE_LICENSE("GPL");
2072 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2073 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2074                    "using following cores: "
2075                    CRYPTO_DRBG_HASH_STRING
2076                    CRYPTO_DRBG_HMAC_STRING
2077                    CRYPTO_DRBG_CTR_STRING);
2078 MODULE_ALIAS_CRYPTO("stdrng");