crypto/drbg.c

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This source file includes following definitions.
drbg_sec_strength
drbg_fips_continuous_test
drbg_cpu_to_be32
drbg_ctr_bcc
drbg_ctr_df
drbg_ctr_update
drbg_ctr_generate
drbg_hmac_update
drbg_hmac_generate
drbg_add_buf
drbg_hash_df
drbg_hash_update
drbg_hash_process_addtl
drbg_hash_hashgen
drbg_hash_generate
__drbg_seed
drbg_get_random_bytes
drbg_async_seed
drbg_seed
drbg_dealloc_state
drbg_alloc_state
drbg_generate
drbg_generate_long
drbg_schedule_async_seed
drbg_prepare_hrng
drbg_instantiate
drbg_uninstantiate
drbg_kcapi_set_entropy
drbg_init_hash_kernel
drbg_fini_hash_kernel
drbg_kcapi_hmacsetkey
drbg_kcapi_hash
drbg_fini_sym_kernel
drbg_init_sym_kernel
drbg_kcapi_symsetkey
drbg_kcapi_sym
drbg_kcapi_sym_ctr
drbg_convert_tfm_core
drbg_kcapi_init
drbg_kcapi_cleanup
drbg_kcapi_random
drbg_kcapi_seed
drbg_healthcheck_sanity
drbg_fill_array
drbg_init
drbg_exit
   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  * FIPS 140-2 continuous self test for the noise source
 224  * The test is performed on the noise source input data. Thus, the function
 225  * implicitly knows the size of the buffer to be equal to the security
 226  * strength.
 227  *
 228  * Note, this function disregards the nonce trailing the entropy data during
 229  * initial seeding.
 230  *
 231  * drbg->drbg_mutex must have been taken.
 232  *
 233  * @drbg DRBG handle
 234  * @entropy buffer of seed data to be checked
 235  *
 236  * return:
 237  *      0 on success
 238  *      -EAGAIN on when the CTRNG is not yet primed
 239  *      < 0 on error
 240  */
 241 static int drbg_fips_continuous_test(struct drbg_state *drbg,
 242                                      const unsigned char *entropy)
 243 {
 244         unsigned short entropylen = drbg_sec_strength(drbg->core->flags);
 245         int ret = 0;
 246 
 247         if (!IS_ENABLED(CONFIG_CRYPTO_FIPS))
 248                 return 0;
 249 
 250         /* skip test if we test the overall system */
 251         if (list_empty(&drbg->test_data.list))
 252                 return 0;
 253         /* only perform test in FIPS mode */
 254         if (!fips_enabled)
 255                 return 0;
 256 
 257         if (!drbg->fips_primed) {
 258                 /* Priming of FIPS test */
 259                 memcpy(drbg->prev, entropy, entropylen);
 260                 drbg->fips_primed = true;
 261                 /* priming: another round is needed */
 262                 return -EAGAIN;
 263         }
 264         ret = memcmp(drbg->prev, entropy, entropylen);
 265         if (!ret)
 266                 panic("DRBG continuous self test failed\n");
 267         memcpy(drbg->prev, entropy, entropylen);
 268 
 269         /* the test shall pass when the two values are not equal */
 270         return 0;
 271 }
 272 
 273 /*
 274  * Convert an integer into a byte representation of this integer.
 275  * The byte representation is big-endian
 276  *
 277  * @val value to be converted
 278  * @buf buffer holding the converted integer -- caller must ensure that
 279  *      buffer size is at least 32 bit
 280  */
 281 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
 282 static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
 283 {
 284         struct s {
 285                 __be32 conv;
 286         };
 287         struct s *conversion = (struct s *) buf;
 288 
 289         conversion->conv = cpu_to_be32(val);
 290 }
 291 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
 292 
 293 /******************************************************************
 294  * CTR DRBG callback functions
 295  ******************************************************************/
 296 
 297 #ifdef CONFIG_CRYPTO_DRBG_CTR
 298 #define CRYPTO_DRBG_CTR_STRING "CTR "
 299 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
 300 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
 301 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
 302 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
 303 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
 304 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");
 305 
 306 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
 307                                  const unsigned char *key);
 308 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
 309                           const struct drbg_string *in);
 310 static int drbg_init_sym_kernel(struct drbg_state *drbg);
 311 static int drbg_fini_sym_kernel(struct drbg_state *drbg);
 312 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
 313                               u8 *inbuf, u32 inbuflen,
 314                               u8 *outbuf, u32 outlen);
 315 #define DRBG_OUTSCRATCHLEN 256
 316 
 317 /* BCC function for CTR DRBG as defined in 10.4.3 */
 318 static int drbg_ctr_bcc(struct drbg_state *drbg,
 319                         unsigned char *out, const unsigned char *key,
 320                         struct list_head *in)
 321 {
 322         int ret = 0;
 323         struct drbg_string *curr = NULL;
 324         struct drbg_string data;
 325         short cnt = 0;
 326 
 327         drbg_string_fill(&data, out, drbg_blocklen(drbg));
 328 
 329         /* 10.4.3 step 2 / 4 */
 330         drbg_kcapi_symsetkey(drbg, key);
 331         list_for_each_entry(curr, in, list) {
 332                 const unsigned char *pos = curr->buf;
 333                 size_t len = curr->len;
 334                 /* 10.4.3 step 4.1 */
 335                 while (len) {
 336                         /* 10.4.3 step 4.2 */
 337                         if (drbg_blocklen(drbg) == cnt) {
 338                                 cnt = 0;
 339                                 ret = drbg_kcapi_sym(drbg, out, &data);
 340                                 if (ret)
 341                                         return ret;
 342                         }
 343                         out[cnt] ^= *pos;
 344                         pos++;
 345                         cnt++;
 346                         len--;
 347                 }
 348         }
 349         /* 10.4.3 step 4.2 for last block */
 350         if (cnt)
 351                 ret = drbg_kcapi_sym(drbg, out, &data);
 352 
 353         return ret;
 354 }
 355 
 356 /*
 357  * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
 358  * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
 359  * the scratchpad is used as follows:
 360  * drbg_ctr_update:
 361  *      temp
 362  *              start: drbg->scratchpad
 363  *              length: drbg_statelen(drbg) + drbg_blocklen(drbg)
 364  *                      note: the cipher writing into this variable works
 365  *                      blocklen-wise. Now, when the statelen is not a multiple
 366  *                      of blocklen, the generateion loop below "spills over"
 367  *                      by at most blocklen. Thus, we need to give sufficient
 368  *                      memory.
 369  *      df_data
 370  *              start: drbg->scratchpad +
 371  *                              drbg_statelen(drbg) + drbg_blocklen(drbg)
 372  *              length: drbg_statelen(drbg)
 373  *
 374  * drbg_ctr_df:
 375  *      pad
 376  *              start: df_data + drbg_statelen(drbg)
 377  *              length: drbg_blocklen(drbg)
 378  *      iv
 379  *              start: pad + drbg_blocklen(drbg)
 380  *              length: drbg_blocklen(drbg)
 381  *      temp
 382  *              start: iv + drbg_blocklen(drbg)
 383  *              length: drbg_satelen(drbg) + drbg_blocklen(drbg)
 384  *                      note: temp is the buffer that the BCC function operates
 385  *                      on. BCC operates blockwise. drbg_statelen(drbg)
 386  *                      is sufficient when the DRBG state length is a multiple
 387  *                      of the block size. For AES192 (and maybe other ciphers)
 388  *                      this is not correct and the length for temp is
 389  *                      insufficient (yes, that also means for such ciphers,
 390  *                      the final output of all BCC rounds are truncated).
 391  *                      Therefore, add drbg_blocklen(drbg) to cover all
 392  *                      possibilities.
 393  */
 394 
 395 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
 396 static int drbg_ctr_df(struct drbg_state *drbg,
 397                        unsigned char *df_data, size_t bytes_to_return,
 398                        struct list_head *seedlist)
 399 {
 400         int ret = -EFAULT;
 401         unsigned char L_N[8];
 402         /* S3 is input */
 403         struct drbg_string S1, S2, S4, cipherin;
 404         LIST_HEAD(bcc_list);
 405         unsigned char *pad = df_data + drbg_statelen(drbg);
 406         unsigned char *iv = pad + drbg_blocklen(drbg);
 407         unsigned char *temp = iv + drbg_blocklen(drbg);
 408         size_t padlen = 0;
 409         unsigned int templen = 0;
 410         /* 10.4.2 step 7 */
 411         unsigned int i = 0;
 412         /* 10.4.2 step 8 */
 413         const unsigned char *K = (unsigned char *)
 414                            "\x00\x01\x02\x03\x04\x05\x06\x07"
 415                            "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
 416                            "\x10\x11\x12\x13\x14\x15\x16\x17"
 417                            "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
 418         unsigned char *X;
 419         size_t generated_len = 0;
 420         size_t inputlen = 0;
 421         struct drbg_string *seed = NULL;
 422 
 423         memset(pad, 0, drbg_blocklen(drbg));
 424         memset(iv, 0, drbg_blocklen(drbg));
 425 
 426         /* 10.4.2 step 1 is implicit as we work byte-wise */
 427 
 428         /* 10.4.2 step 2 */
 429         if ((512/8) < bytes_to_return)
 430                 return -EINVAL;
 431 
 432         /* 10.4.2 step 2 -- calculate the entire length of all input data */
 433         list_for_each_entry(seed, seedlist, list)
 434                 inputlen += seed->len;
 435         drbg_cpu_to_be32(inputlen, &L_N[0]);
 436 
 437         /* 10.4.2 step 3 */
 438         drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
 439 
 440         /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
 441         padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
 442         /* wrap the padlen appropriately */
 443         if (padlen)
 444                 padlen = drbg_blocklen(drbg) - padlen;
 445         /*
 446          * pad / padlen contains the 0x80 byte and the following zero bytes.
 447          * As the calculated padlen value only covers the number of zero
 448          * bytes, this value has to be incremented by one for the 0x80 byte.
 449          */
 450         padlen++;
 451         pad[0] = 0x80;
 452 
 453         /* 10.4.2 step 4 -- first fill the linked list and then order it */
 454         drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
 455         list_add_tail(&S1.list, &bcc_list);
 456         drbg_string_fill(&S2, L_N, sizeof(L_N));
 457         list_add_tail(&S2.list, &bcc_list);
 458         list_splice_tail(seedlist, &bcc_list);
 459         drbg_string_fill(&S4, pad, padlen);
 460         list_add_tail(&S4.list, &bcc_list);
 461 
 462         /* 10.4.2 step 9 */
 463         while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
 464                 /*
 465                  * 10.4.2 step 9.1 - the padding is implicit as the buffer
 466                  * holds zeros after allocation -- even the increment of i
 467                  * is irrelevant as the increment remains within length of i
 468                  */
 469                 drbg_cpu_to_be32(i, iv);
 470                 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
 471                 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
 472                 if (ret)
 473                         goto out;
 474                 /* 10.4.2 step 9.3 */
 475                 i++;
 476                 templen += drbg_blocklen(drbg);
 477         }
 478 
 479         /* 10.4.2 step 11 */
 480         X = temp + (drbg_keylen(drbg));
 481         drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
 482 
 483         /* 10.4.2 step 12: overwriting of outval is implemented in next step */
 484 
 485         /* 10.4.2 step 13 */
 486         drbg_kcapi_symsetkey(drbg, temp);
 487         while (generated_len < bytes_to_return) {
 488                 short blocklen = 0;
 489                 /*
 490                  * 10.4.2 step 13.1: the truncation of the key length is
 491                  * implicit as the key is only drbg_blocklen in size based on
 492                  * the implementation of the cipher function callback
 493                  */
 494                 ret = drbg_kcapi_sym(drbg, X, &cipherin);
 495                 if (ret)
 496                         goto out;
 497                 blocklen = (drbg_blocklen(drbg) <
 498                                 (bytes_to_return - generated_len)) ?
 499                             drbg_blocklen(drbg) :
 500                                 (bytes_to_return - generated_len);
 501                 /* 10.4.2 step 13.2 and 14 */
 502                 memcpy(df_data + generated_len, X, blocklen);
 503                 generated_len += blocklen;
 504         }
 505 
 506         ret = 0;
 507 
 508 out:
 509         memset(iv, 0, drbg_blocklen(drbg));
 510         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 511         memset(pad, 0, drbg_blocklen(drbg));
 512         return ret;
 513 }
 514 
 515 /*
 516  * update function of CTR DRBG as defined in 10.2.1.2
 517  *
 518  * The reseed variable has an enhanced meaning compared to the update
 519  * functions of the other DRBGs as follows:
 520  * 0 => initial seed from initialization
 521  * 1 => reseed via drbg_seed
 522  * 2 => first invocation from drbg_ctr_update when addtl is present. In
 523  *      this case, the df_data scratchpad is not deleted so that it is
 524  *      available for another calls to prevent calling the DF function
 525  *      again.
 526  * 3 => second invocation from drbg_ctr_update. When the update function
 527  *      was called with addtl, the df_data memory already contains the
 528  *      DFed addtl information and we do not need to call DF again.
 529  */
 530 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
 531                            int reseed)
 532 {
 533         int ret = -EFAULT;
 534         /* 10.2.1.2 step 1 */
 535         unsigned char *temp = drbg->scratchpad;
 536         unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
 537                                  drbg_blocklen(drbg);
 538 
 539         if (3 > reseed)
 540                 memset(df_data, 0, drbg_statelen(drbg));
 541 
 542         if (!reseed) {
 543                 /*
 544                  * The DRBG uses the CTR mode of the underlying AES cipher. The
 545                  * CTR mode increments the counter value after the AES operation
 546                  * but SP800-90A requires that the counter is incremented before
 547                  * the AES operation. Hence, we increment it at the time we set
 548                  * it by one.
 549                  */
 550                 crypto_inc(drbg->V, drbg_blocklen(drbg));
 551 
 552                 ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
 553                                              drbg_keylen(drbg));
 554                 if (ret)
 555                         goto out;
 556         }
 557 
 558         /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
 559         if (seed) {
 560                 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
 561                 if (ret)
 562                         goto out;
 563         }
 564 
 565         ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
 566                                  temp, drbg_statelen(drbg));
 567         if (ret)
 568                 return ret;
 569 
 570         /* 10.2.1.2 step 5 */
 571         ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
 572                                      drbg_keylen(drbg));
 573         if (ret)
 574                 goto out;
 575         /* 10.2.1.2 step 6 */
 576         memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
 577         /* See above: increment counter by one to compensate timing of CTR op */
 578         crypto_inc(drbg->V, drbg_blocklen(drbg));
 579         ret = 0;
 580 
 581 out:
 582         memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 583         if (2 != reseed)
 584                 memset(df_data, 0, drbg_statelen(drbg));
 585         return ret;
 586 }
 587 
 588 /*
 589  * scratchpad use: drbg_ctr_update is called independently from
 590  * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
 591  */
 592 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
 593 static int drbg_ctr_generate(struct drbg_state *drbg,
 594                              unsigned char *buf, unsigned int buflen,
 595                              struct list_head *addtl)
 596 {
 597         int ret;
 598         int len = min_t(int, buflen, INT_MAX);
 599 
 600         /* 10.2.1.5.2 step 2 */
 601         if (addtl && !list_empty(addtl)) {
 602                 ret = drbg_ctr_update(drbg, addtl, 2);
 603                 if (ret)
 604                         return 0;
 605         }
 606 
 607         /* 10.2.1.5.2 step 4.1 */
 608         ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len);
 609         if (ret)
 610                 return ret;
 611 
 612         /* 10.2.1.5.2 step 6 */
 613         ret = drbg_ctr_update(drbg, NULL, 3);
 614         if (ret)
 615                 len = ret;
 616 
 617         return len;
 618 }
 619 
 620 static const struct drbg_state_ops drbg_ctr_ops = {
 621         .update         = drbg_ctr_update,
 622         .generate       = drbg_ctr_generate,
 623         .crypto_init    = drbg_init_sym_kernel,
 624         .crypto_fini    = drbg_fini_sym_kernel,
 625 };
 626 #endif /* CONFIG_CRYPTO_DRBG_CTR */
 627 
 628 /******************************************************************
 629  * HMAC DRBG callback functions
 630  ******************************************************************/
 631 
 632 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
 633 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
 634                            const struct list_head *in);
 635 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
 636                                   const unsigned char *key);
 637 static int drbg_init_hash_kernel(struct drbg_state *drbg);
 638 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
 639 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
 640 
 641 #ifdef CONFIG_CRYPTO_DRBG_HMAC
 642 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
 643 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
 644 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
 645 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
 646 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
 647 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
 648 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
 649 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
 650 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
 651 
 652 /* update function of HMAC DRBG as defined in 10.1.2.2 */
 653 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
 654                             int reseed)
 655 {
 656         int ret = -EFAULT;
 657         int i = 0;
 658         struct drbg_string seed1, seed2, vdata;
 659         LIST_HEAD(seedlist);
 660         LIST_HEAD(vdatalist);
 661 
 662         if (!reseed) {
 663                 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
 664                 memset(drbg->V, 1, drbg_statelen(drbg));
 665                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
 666         }
 667 
 668         drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
 669         list_add_tail(&seed1.list, &seedlist);
 670         /* buffer of seed2 will be filled in for loop below with one byte */
 671         drbg_string_fill(&seed2, NULL, 1);
 672         list_add_tail(&seed2.list, &seedlist);
 673         /* input data of seed is allowed to be NULL at this point */
 674         if (seed)
 675                 list_splice_tail(seed, &seedlist);
 676 
 677         drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
 678         list_add_tail(&vdata.list, &vdatalist);
 679         for (i = 2; 0 < i; i--) {
 680                 /* first round uses 0x0, second 0x1 */
 681                 unsigned char prefix = DRBG_PREFIX0;
 682                 if (1 == i)
 683                         prefix = DRBG_PREFIX1;
 684                 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
 685                 seed2.buf = &prefix;
 686                 ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
 687                 if (ret)
 688                         return ret;
 689                 drbg_kcapi_hmacsetkey(drbg, drbg->C);
 690 
 691                 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
 692                 ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
 693                 if (ret)
 694                         return ret;
 695 
 696                 /* 10.1.2.2 step 3 */
 697                 if (!seed)
 698                         return ret;
 699         }
 700 
 701         return 0;
 702 }
 703 
 704 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
 705 static int drbg_hmac_generate(struct drbg_state *drbg,
 706                               unsigned char *buf,
 707                               unsigned int buflen,
 708                               struct list_head *addtl)
 709 {
 710         int len = 0;
 711         int ret = 0;
 712         struct drbg_string data;
 713         LIST_HEAD(datalist);
 714 
 715         /* 10.1.2.5 step 2 */
 716         if (addtl && !list_empty(addtl)) {
 717                 ret = drbg_hmac_update(drbg, addtl, 1);
 718                 if (ret)
 719                         return ret;
 720         }
 721 
 722         drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
 723         list_add_tail(&data.list, &datalist);
 724         while (len < buflen) {
 725                 unsigned int outlen = 0;
 726                 /* 10.1.2.5 step 4.1 */
 727                 ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
 728                 if (ret)
 729                         return ret;
 730                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 731                           drbg_blocklen(drbg) : (buflen - len);
 732 
 733                 /* 10.1.2.5 step 4.2 */
 734                 memcpy(buf + len, drbg->V, outlen);
 735                 len += outlen;
 736         }
 737 
 738         /* 10.1.2.5 step 6 */
 739         if (addtl && !list_empty(addtl))
 740                 ret = drbg_hmac_update(drbg, addtl, 1);
 741         else
 742                 ret = drbg_hmac_update(drbg, NULL, 1);
 743         if (ret)
 744                 return ret;
 745 
 746         return len;
 747 }
 748 
 749 static const struct drbg_state_ops drbg_hmac_ops = {
 750         .update         = drbg_hmac_update,
 751         .generate       = drbg_hmac_generate,
 752         .crypto_init    = drbg_init_hash_kernel,
 753         .crypto_fini    = drbg_fini_hash_kernel,
 754 };
 755 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
 756 
 757 /******************************************************************
 758  * Hash DRBG callback functions
 759  ******************************************************************/
 760 
 761 #ifdef CONFIG_CRYPTO_DRBG_HASH
 762 #define CRYPTO_DRBG_HASH_STRING "HASH "
 763 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
 764 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
 765 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
 766 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
 767 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
 768 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
 769 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
 770 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
 771 
 772 /*
 773  * Increment buffer
 774  *
 775  * @dst buffer to increment
 776  * @add value to add
 777  */
 778 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
 779                                 const unsigned char *add, size_t addlen)
 780 {
 781         /* implied: dstlen > addlen */
 782         unsigned char *dstptr;
 783         const unsigned char *addptr;
 784         unsigned int remainder = 0;
 785         size_t len = addlen;
 786 
 787         dstptr = dst + (dstlen-1);
 788         addptr = add + (addlen-1);
 789         while (len) {
 790                 remainder += *dstptr + *addptr;
 791                 *dstptr = remainder & 0xff;
 792                 remainder >>= 8;
 793                 len--; dstptr--; addptr--;
 794         }
 795         len = dstlen - addlen;
 796         while (len && remainder > 0) {
 797                 remainder = *dstptr + 1;
 798                 *dstptr = remainder & 0xff;
 799                 remainder >>= 8;
 800                 len--; dstptr--;
 801         }
 802 }
 803 
 804 /*
 805  * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
 806  * interlinked, the scratchpad is used as follows:
 807  * drbg_hash_update
 808  *      start: drbg->scratchpad
 809  *      length: drbg_statelen(drbg)
 810  * drbg_hash_df:
 811  *      start: drbg->scratchpad + drbg_statelen(drbg)
 812  *      length: drbg_blocklen(drbg)
 813  *
 814  * drbg_hash_process_addtl uses the scratchpad, but fully completes
 815  * before either of the functions mentioned before are invoked. Therefore,
 816  * drbg_hash_process_addtl does not need to be specifically considered.
 817  */
 818 
 819 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
 820 static int drbg_hash_df(struct drbg_state *drbg,
 821                         unsigned char *outval, size_t outlen,
 822                         struct list_head *entropylist)
 823 {
 824         int ret = 0;
 825         size_t len = 0;
 826         unsigned char input[5];
 827         unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
 828         struct drbg_string data;
 829 
 830         /* 10.4.1 step 3 */
 831         input[0] = 1;
 832         drbg_cpu_to_be32((outlen * 8), &input[1]);
 833 
 834         /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
 835         drbg_string_fill(&data, input, 5);
 836         list_add(&data.list, entropylist);
 837 
 838         /* 10.4.1 step 4 */
 839         while (len < outlen) {
 840                 short blocklen = 0;
 841                 /* 10.4.1 step 4.1 */
 842                 ret = drbg_kcapi_hash(drbg, tmp, entropylist);
 843                 if (ret)
 844                         goto out;
 845                 /* 10.4.1 step 4.2 */
 846                 input[0]++;
 847                 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
 848                             drbg_blocklen(drbg) : (outlen - len);
 849                 memcpy(outval + len, tmp, blocklen);
 850                 len += blocklen;
 851         }
 852 
 853 out:
 854         memset(tmp, 0, drbg_blocklen(drbg));
 855         return ret;
 856 }
 857 
 858 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
 859 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
 860                             int reseed)
 861 {
 862         int ret = 0;
 863         struct drbg_string data1, data2;
 864         LIST_HEAD(datalist);
 865         LIST_HEAD(datalist2);
 866         unsigned char *V = drbg->scratchpad;
 867         unsigned char prefix = DRBG_PREFIX1;
 868 
 869         if (!seed)
 870                 return -EINVAL;
 871 
 872         if (reseed) {
 873                 /* 10.1.1.3 step 1 */
 874                 memcpy(V, drbg->V, drbg_statelen(drbg));
 875                 drbg_string_fill(&data1, &prefix, 1);
 876                 list_add_tail(&data1.list, &datalist);
 877                 drbg_string_fill(&data2, V, drbg_statelen(drbg));
 878                 list_add_tail(&data2.list, &datalist);
 879         }
 880         list_splice_tail(seed, &datalist);
 881 
 882         /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
 883         ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
 884         if (ret)
 885                 goto out;
 886 
 887         /* 10.1.1.2 / 10.1.1.3 step 4  */
 888         prefix = DRBG_PREFIX0;
 889         drbg_string_fill(&data1, &prefix, 1);
 890         list_add_tail(&data1.list, &datalist2);
 891         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 892         list_add_tail(&data2.list, &datalist2);
 893         /* 10.1.1.2 / 10.1.1.3 step 4 */
 894         ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
 895 
 896 out:
 897         memset(drbg->scratchpad, 0, drbg_statelen(drbg));
 898         return ret;
 899 }
 900 
 901 /* processing of additional information string for Hash DRBG */
 902 static int drbg_hash_process_addtl(struct drbg_state *drbg,
 903                                    struct list_head *addtl)
 904 {
 905         int ret = 0;
 906         struct drbg_string data1, data2;
 907         LIST_HEAD(datalist);
 908         unsigned char prefix = DRBG_PREFIX2;
 909 
 910         /* 10.1.1.4 step 2 */
 911         if (!addtl || list_empty(addtl))
 912                 return 0;
 913 
 914         /* 10.1.1.4 step 2a */
 915         drbg_string_fill(&data1, &prefix, 1);
 916         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 917         list_add_tail(&data1.list, &datalist);
 918         list_add_tail(&data2.list, &datalist);
 919         list_splice_tail(addtl, &datalist);
 920         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
 921         if (ret)
 922                 goto out;
 923 
 924         /* 10.1.1.4 step 2b */
 925         drbg_add_buf(drbg->V, drbg_statelen(drbg),
 926                      drbg->scratchpad, drbg_blocklen(drbg));
 927 
 928 out:
 929         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 930         return ret;
 931 }
 932 
 933 /* Hashgen defined in 10.1.1.4 */
 934 static int drbg_hash_hashgen(struct drbg_state *drbg,
 935                              unsigned char *buf,
 936                              unsigned int buflen)
 937 {
 938         int len = 0;
 939         int ret = 0;
 940         unsigned char *src = drbg->scratchpad;
 941         unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
 942         struct drbg_string data;
 943         LIST_HEAD(datalist);
 944 
 945         /* 10.1.1.4 step hashgen 2 */
 946         memcpy(src, drbg->V, drbg_statelen(drbg));
 947 
 948         drbg_string_fill(&data, src, drbg_statelen(drbg));
 949         list_add_tail(&data.list, &datalist);
 950         while (len < buflen) {
 951                 unsigned int outlen = 0;
 952                 /* 10.1.1.4 step hashgen 4.1 */
 953                 ret = drbg_kcapi_hash(drbg, dst, &datalist);
 954                 if (ret) {
 955                         len = ret;
 956                         goto out;
 957                 }
 958                 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 959                           drbg_blocklen(drbg) : (buflen - len);
 960                 /* 10.1.1.4 step hashgen 4.2 */
 961                 memcpy(buf + len, dst, outlen);
 962                 len += outlen;
 963                 /* 10.1.1.4 hashgen step 4.3 */
 964                 if (len < buflen)
 965                         crypto_inc(src, drbg_statelen(drbg));
 966         }
 967 
 968 out:
 969         memset(drbg->scratchpad, 0,
 970                (drbg_statelen(drbg) + drbg_blocklen(drbg)));
 971         return len;
 972 }
 973 
 974 /* generate function for Hash DRBG as defined in  10.1.1.4 */
 975 static int drbg_hash_generate(struct drbg_state *drbg,
 976                               unsigned char *buf, unsigned int buflen,
 977                               struct list_head *addtl)
 978 {
 979         int len = 0;
 980         int ret = 0;
 981         union {
 982                 unsigned char req[8];
 983                 __be64 req_int;
 984         } u;
 985         unsigned char prefix = DRBG_PREFIX3;
 986         struct drbg_string data1, data2;
 987         LIST_HEAD(datalist);
 988 
 989         /* 10.1.1.4 step 2 */
 990         ret = drbg_hash_process_addtl(drbg, addtl);
 991         if (ret)
 992                 return ret;
 993         /* 10.1.1.4 step 3 */
 994         len = drbg_hash_hashgen(drbg, buf, buflen);
 995 
 996         /* this is the value H as documented in 10.1.1.4 */
 997         /* 10.1.1.4 step 4 */
 998         drbg_string_fill(&data1, &prefix, 1);
 999         list_add_tail(&data1.list, &datalist);
1000         drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
1001         list_add_tail(&data2.list, &datalist);
1002         ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
1003         if (ret) {
1004                 len = ret;
1005                 goto out;
1006         }
1007 
1008         /* 10.1.1.4 step 5 */
1009         drbg_add_buf(drbg->V, drbg_statelen(drbg),
1010                      drbg->scratchpad, drbg_blocklen(drbg));
1011         drbg_add_buf(drbg->V, drbg_statelen(drbg),
1012                      drbg->C, drbg_statelen(drbg));
1013         u.req_int = cpu_to_be64(drbg->reseed_ctr);
1014         drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
1015 
1016 out:
1017         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
1018         return len;
1019 }
1020 
1021 /*
1022  * scratchpad usage: as update and generate are used isolated, both
1023  * can use the scratchpad
1024  */
1025 static const struct drbg_state_ops drbg_hash_ops = {
1026         .update         = drbg_hash_update,
1027         .generate       = drbg_hash_generate,
1028         .crypto_init    = drbg_init_hash_kernel,
1029         .crypto_fini    = drbg_fini_hash_kernel,
1030 };
1031 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1032 
1033 /******************************************************************
1034  * Functions common for DRBG implementations
1035  ******************************************************************/
1036 
1037 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
1038                               int reseed)
1039 {
1040         int ret = drbg->d_ops->update(drbg, seed, reseed);
1041 
1042         if (ret)
1043                 return ret;
1044 
1045         drbg->seeded = true;
1046         /* 10.1.1.2 / 10.1.1.3 step 5 */
1047         drbg->reseed_ctr = 1;
1048 
1049         return ret;
1050 }
1051 
1052 static inline int drbg_get_random_bytes(struct drbg_state *drbg,
1053                                         unsigned char *entropy,
1054                                         unsigned int entropylen)
1055 {
1056         int ret;
1057 
1058         do {
1059                 get_random_bytes(entropy, entropylen);
1060                 ret = drbg_fips_continuous_test(drbg, entropy);
1061                 if (ret && ret != -EAGAIN)
1062                         return ret;
1063         } while (ret);
1064 
1065         return 0;
1066 }
1067 
1068 static void drbg_async_seed(struct work_struct *work)
1069 {
1070         struct drbg_string data;
1071         LIST_HEAD(seedlist);
1072         struct drbg_state *drbg = container_of(work, struct drbg_state,
1073                                                seed_work);
1074         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1075         unsigned char entropy[32];
1076         int ret;
1077 
1078         BUG_ON(!entropylen);
1079         BUG_ON(entropylen > sizeof(entropy));
1080 
1081         drbg_string_fill(&data, entropy, entropylen);
1082         list_add_tail(&data.list, &seedlist);
1083 
1084         mutex_lock(&drbg->drbg_mutex);
1085 
1086         ret = drbg_get_random_bytes(drbg, entropy, entropylen);
1087         if (ret)
1088                 goto unlock;
1089 
1090         /* If nonblocking pool is initialized, deactivate Jitter RNG */
1091         crypto_free_rng(drbg->jent);
1092         drbg->jent = NULL;
1093 
1094         /* Set seeded to false so that if __drbg_seed fails the
1095          * next generate call will trigger a reseed.
1096          */
1097         drbg->seeded = false;
1098 
1099         __drbg_seed(drbg, &seedlist, true);
1100 
1101         if (drbg->seeded)
1102                 drbg->reseed_threshold = drbg_max_requests(drbg);
1103 
1104 unlock:
1105         mutex_unlock(&drbg->drbg_mutex);
1106 
1107         memzero_explicit(entropy, entropylen);
1108 }
1109 
1110 /*
1111  * Seeding or reseeding of the DRBG
1112  *
1113  * @drbg: DRBG state struct
1114  * @pers: personalization / additional information buffer
1115  * @reseed: 0 for initial seed process, 1 for reseeding
1116  *
1117  * return:
1118  *      0 on success
1119  *      error value otherwise
1120  */
1121 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1122                      bool reseed)
1123 {
1124         int ret;
1125         unsigned char entropy[((32 + 16) * 2)];
1126         unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1127         struct drbg_string data1;
1128         LIST_HEAD(seedlist);
1129 
1130         /* 9.1 / 9.2 / 9.3.1 step 3 */
1131         if (pers && pers->len > (drbg_max_addtl(drbg))) {
1132                 pr_devel("DRBG: personalization string too long %zu\n",
1133                          pers->len);
1134                 return -EINVAL;
1135         }
1136 
1137         if (list_empty(&drbg->test_data.list)) {
1138                 drbg_string_fill(&data1, drbg->test_data.buf,
1139                                  drbg->test_data.len);
1140                 pr_devel("DRBG: using test entropy\n");
1141         } else {
1142                 /*
1143                  * Gather entropy equal to the security strength of the DRBG.
1144                  * With a derivation function, a nonce is required in addition
1145                  * to the entropy. A nonce must be at least 1/2 of the security
1146                  * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1147                  * of the strength. The consideration of a nonce is only
1148                  * applicable during initial seeding.
1149                  */
1150                 BUG_ON(!entropylen);
1151                 if (!reseed)
1152                         entropylen = ((entropylen + 1) / 2) * 3;
1153                 BUG_ON((entropylen * 2) > sizeof(entropy));
1154 
1155                 /* Get seed from in-kernel /dev/urandom */
1156                 ret = drbg_get_random_bytes(drbg, entropy, entropylen);
1157                 if (ret)
1158                         goto out;
1159 
1160                 if (!drbg->jent) {
1161                         drbg_string_fill(&data1, entropy, entropylen);
1162                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1163                                  entropylen);
1164                 } else {
1165                         /* Get seed from Jitter RNG */
1166                         ret = crypto_rng_get_bytes(drbg->jent,
1167                                                    entropy + entropylen,
1168                                                    entropylen);
1169                         if (ret) {
1170                                 pr_devel("DRBG: jent failed with %d\n", ret);
1171                                 goto out;
1172                         }
1173 
1174                         drbg_string_fill(&data1, entropy, entropylen * 2);
1175                         pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1176                                  entropylen * 2);
1177                 }
1178         }
1179         list_add_tail(&data1.list, &seedlist);
1180 
1181         /*
1182          * concatenation of entropy with personalization str / addtl input)
1183          * the variable pers is directly handed in by the caller, so check its
1184          * contents whether it is appropriate
1185          */
1186         if (pers && pers->buf && 0 < pers->len) {
1187                 list_add_tail(&pers->list, &seedlist);
1188                 pr_devel("DRBG: using personalization string\n");
1189         }
1190 
1191         if (!reseed) {
1192                 memset(drbg->V, 0, drbg_statelen(drbg));
1193                 memset(drbg->C, 0, drbg_statelen(drbg));
1194         }
1195 
1196         ret = __drbg_seed(drbg, &seedlist, reseed);
1197 
1198 out:
1199         memzero_explicit(entropy, entropylen * 2);
1200 
1201         return ret;
1202 }
1203 
1204 /* Free all substructures in a DRBG state without the DRBG state structure */
1205 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1206 {
1207         if (!drbg)
1208                 return;
1209         kzfree(drbg->Vbuf);
1210         drbg->Vbuf = NULL;
1211         drbg->V = NULL;
1212         kzfree(drbg->Cbuf);
1213         drbg->Cbuf = NULL;
1214         drbg->C = NULL;
1215         kzfree(drbg->scratchpadbuf);
1216         drbg->scratchpadbuf = NULL;
1217         drbg->reseed_ctr = 0;
1218         drbg->d_ops = NULL;
1219         drbg->core = NULL;
1220         if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
1221                 kzfree(drbg->prev);
1222                 drbg->prev = NULL;
1223                 drbg->fips_primed = false;
1224         }
1225 }
1226 
1227 /*
1228  * Allocate all sub-structures for a DRBG state.
1229  * The DRBG state structure must already be allocated.
1230  */
1231 static inline int drbg_alloc_state(struct drbg_state *drbg)
1232 {
1233         int ret = -ENOMEM;
1234         unsigned int sb_size = 0;
1235 
1236         switch (drbg->core->flags & DRBG_TYPE_MASK) {
1237 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1238         case DRBG_HMAC:
1239                 drbg->d_ops = &drbg_hmac_ops;
1240                 break;
1241 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1242 #ifdef CONFIG_CRYPTO_DRBG_HASH
1243         case DRBG_HASH:
1244                 drbg->d_ops = &drbg_hash_ops;
1245                 break;
1246 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1247 #ifdef CONFIG_CRYPTO_DRBG_CTR
1248         case DRBG_CTR:
1249                 drbg->d_ops = &drbg_ctr_ops;
1250                 break;
1251 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1252         default:
1253                 ret = -EOPNOTSUPP;
1254                 goto err;
1255         }
1256 
1257         ret = drbg->d_ops->crypto_init(drbg);
1258         if (ret < 0)
1259                 goto err;
1260 
1261         drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1262         if (!drbg->Vbuf) {
1263                 ret = -ENOMEM;
1264                 goto fini;
1265         }
1266         drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
1267         drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1268         if (!drbg->Cbuf) {
1269                 ret = -ENOMEM;
1270                 goto fini;
1271         }
1272         drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);
1273         /* scratchpad is only generated for CTR and Hash */
1274         if (drbg->core->flags & DRBG_HMAC)
1275                 sb_size = 0;
1276         else if (drbg->core->flags & DRBG_CTR)
1277                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1278                           drbg_statelen(drbg) + /* df_data */
1279                           drbg_blocklen(drbg) + /* pad */
1280                           drbg_blocklen(drbg) + /* iv */
1281                           drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1282         else
1283                 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1284 
1285         if (0 < sb_size) {
1286                 drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);
1287                 if (!drbg->scratchpadbuf) {
1288                         ret = -ENOMEM;
1289                         goto fini;
1290                 }
1291                 drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);
1292         }
1293 
1294         if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
1295                 drbg->prev = kzalloc(drbg_sec_strength(drbg->core->flags),
1296                                      GFP_KERNEL);
1297                 if (!drbg->prev) {
1298                         ret = -ENOMEM;
1299                         goto fini;
1300                 }
1301                 drbg->fips_primed = false;
1302         }
1303 
1304         return 0;
1305 
1306 fini:
1307         drbg->d_ops->crypto_fini(drbg);
1308 err:
1309         drbg_dealloc_state(drbg);
1310         return ret;
1311 }
1312 
1313 /*************************************************************************
1314  * DRBG interface functions
1315  *************************************************************************/
1316 
1317 /*
1318  * DRBG generate function as required by SP800-90A - this function
1319  * generates random numbers
1320  *
1321  * @drbg DRBG state handle
1322  * @buf Buffer where to store the random numbers -- the buffer must already
1323  *      be pre-allocated by caller
1324  * @buflen Length of output buffer - this value defines the number of random
1325  *         bytes pulled from DRBG
1326  * @addtl Additional input that is mixed into state, may be NULL -- note
1327  *        the entropy is pulled by the DRBG internally unconditionally
1328  *        as defined in SP800-90A. The additional input is mixed into
1329  *        the state in addition to the pulled entropy.
1330  *
1331  * return: 0 when all bytes are generated; < 0 in case of an error
1332  */
1333 static int drbg_generate(struct drbg_state *drbg,
1334                          unsigned char *buf, unsigned int buflen,
1335                          struct drbg_string *addtl)
1336 {
1337         int len = 0;
1338         LIST_HEAD(addtllist);
1339 
1340         if (!drbg->core) {
1341                 pr_devel("DRBG: not yet seeded\n");
1342                 return -EINVAL;
1343         }
1344         if (0 == buflen || !buf) {
1345                 pr_devel("DRBG: no output buffer provided\n");
1346                 return -EINVAL;
1347         }
1348         if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1349                 pr_devel("DRBG: wrong format of additional information\n");
1350                 return -EINVAL;
1351         }
1352 
1353         /* 9.3.1 step 2 */
1354         len = -EINVAL;
1355         if (buflen > (drbg_max_request_bytes(drbg))) {
1356                 pr_devel("DRBG: requested random numbers too large %u\n",
1357                          buflen);
1358                 goto err;
1359         }
1360 
1361         /* 9.3.1 step 3 is implicit with the chosen DRBG */
1362 
1363         /* 9.3.1 step 4 */
1364         if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1365                 pr_devel("DRBG: additional information string too long %zu\n",
1366                          addtl->len);
1367                 goto err;
1368         }
1369         /* 9.3.1 step 5 is implicit with the chosen DRBG */
1370 
1371         /*
1372          * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1373          * here. The spec is a bit convoluted here, we make it simpler.
1374          */
1375         if (drbg->reseed_threshold < drbg->reseed_ctr)
1376                 drbg->seeded = false;
1377 
1378         if (drbg->pr || !drbg->seeded) {
1379                 pr_devel("DRBG: reseeding before generation (prediction "
1380                          "resistance: %s, state %s)\n",
1381                          drbg->pr ? "true" : "false",
1382                          drbg->seeded ? "seeded" : "unseeded");
1383                 /* 9.3.1 steps 7.1 through 7.3 */
1384                 len = drbg_seed(drbg, addtl, true);
1385                 if (len)
1386                         goto err;
1387                 /* 9.3.1 step 7.4 */
1388                 addtl = NULL;
1389         }
1390 
1391         if (addtl && 0 < addtl->len)
1392                 list_add_tail(&addtl->list, &addtllist);
1393         /* 9.3.1 step 8 and 10 */
1394         len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1395 
1396         /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1397         drbg->reseed_ctr++;
1398         if (0 >= len)
1399                 goto err;
1400 
1401         /*
1402          * Section 11.3.3 requires to re-perform self tests after some
1403          * generated random numbers. The chosen value after which self
1404          * test is performed is arbitrary, but it should be reasonable.
1405          * However, we do not perform the self tests because of the following
1406          * reasons: it is mathematically impossible that the initial self tests
1407          * were successfully and the following are not. If the initial would
1408          * pass and the following would not, the kernel integrity is violated.
1409          * In this case, the entire kernel operation is questionable and it
1410          * is unlikely that the integrity violation only affects the
1411          * correct operation of the DRBG.
1412          *
1413          * Albeit the following code is commented out, it is provided in
1414          * case somebody has a need to implement the test of 11.3.3.
1415          */
1416 #if 0
1417         if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1418                 int err = 0;
1419                 pr_devel("DRBG: start to perform self test\n");
1420                 if (drbg->core->flags & DRBG_HMAC)
1421                         err = alg_test("drbg_pr_hmac_sha256",
1422                                        "drbg_pr_hmac_sha256", 0, 0);
1423                 else if (drbg->core->flags & DRBG_CTR)
1424                         err = alg_test("drbg_pr_ctr_aes128",
1425                                        "drbg_pr_ctr_aes128", 0, 0);
1426                 else
1427                         err = alg_test("drbg_pr_sha256",
1428                                        "drbg_pr_sha256", 0, 0);
1429                 if (err) {
1430                         pr_err("DRBG: periodical self test failed\n");
1431                         /*
1432                          * uninstantiate implies that from now on, only errors
1433                          * are returned when reusing this DRBG cipher handle
1434                          */
1435                         drbg_uninstantiate(drbg);
1436                         return 0;
1437                 } else {
1438                         pr_devel("DRBG: self test successful\n");
1439                 }
1440         }
1441 #endif
1442 
1443         /*
1444          * All operations were successful, return 0 as mandated by
1445          * the kernel crypto API interface.
1446          */
1447         len = 0;
1448 err:
1449         return len;
1450 }
1451 
1452 /*
1453  * Wrapper around drbg_generate which can pull arbitrary long strings
1454  * from the DRBG without hitting the maximum request limitation.
1455  *
1456  * Parameters: see drbg_generate
1457  * Return codes: see drbg_generate -- if one drbg_generate request fails,
1458  *               the entire drbg_generate_long request fails
1459  */
1460 static int drbg_generate_long(struct drbg_state *drbg,
1461                               unsigned char *buf, unsigned int buflen,
1462                               struct drbg_string *addtl)
1463 {
1464         unsigned int len = 0;
1465         unsigned int slice = 0;
1466         do {
1467                 int err = 0;
1468                 unsigned int chunk = 0;
1469                 slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1470                 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1471                 mutex_lock(&drbg->drbg_mutex);
1472                 err = drbg_generate(drbg, buf + len, chunk, addtl);
1473                 mutex_unlock(&drbg->drbg_mutex);
1474                 if (0 > err)
1475                         return err;
1476                 len += chunk;
1477         } while (slice > 0 && (len < buflen));
1478         return 0;
1479 }
1480 
1481 static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
1482 {
1483         struct drbg_state *drbg = container_of(rdy, struct drbg_state,
1484                                                random_ready);
1485 
1486         schedule_work(&drbg->seed_work);
1487 }
1488 
1489 static int drbg_prepare_hrng(struct drbg_state *drbg)
1490 {
1491         int err;
1492 
1493         /* We do not need an HRNG in test mode. */
1494         if (list_empty(&drbg->test_data.list))
1495                 return 0;
1496 
1497         INIT_WORK(&drbg->seed_work, drbg_async_seed);
1498 
1499         drbg->random_ready.owner = THIS_MODULE;
1500         drbg->random_ready.func = drbg_schedule_async_seed;
1501 
1502         err = add_random_ready_callback(&drbg->random_ready);
1503 
1504         switch (err) {
1505         case 0:
1506                 break;
1507 
1508         case -EALREADY:
1509                 err = 0;
1510                 /* fall through */
1511 
1512         default:
1513                 drbg->random_ready.func = NULL;
1514                 return err;
1515         }
1516 
1517         drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
1518 
1519         /*
1520          * Require frequent reseeds until the seed source is fully
1521          * initialized.
1522          */
1523         drbg->reseed_threshold = 50;
1524 
1525         return err;
1526 }
1527 
1528 /*
1529  * DRBG instantiation function as required by SP800-90A - this function
1530  * sets up the DRBG handle, performs the initial seeding and all sanity
1531  * checks required by SP800-90A
1532  *
1533  * @drbg memory of state -- if NULL, new memory is allocated
1534  * @pers Personalization string that is mixed into state, may be NULL -- note
1535  *       the entropy is pulled by the DRBG internally unconditionally
1536  *       as defined in SP800-90A. The additional input is mixed into
1537  *       the state in addition to the pulled entropy.
1538  * @coreref reference to core
1539  * @pr prediction resistance enabled
1540  *
1541  * return
1542  *      0 on success
1543  *      error value otherwise
1544  */
1545 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1546                             int coreref, bool pr)
1547 {
1548         int ret;
1549         bool reseed = true;
1550 
1551         pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1552                  "%s\n", coreref, pr ? "enabled" : "disabled");
1553         mutex_lock(&drbg->drbg_mutex);
1554 
1555         /* 9.1 step 1 is implicit with the selected DRBG type */
1556 
1557         /*
1558          * 9.1 step 2 is implicit as caller can select prediction resistance
1559          * and the flag is copied into drbg->flags --
1560          * all DRBG types support prediction resistance
1561          */
1562 
1563         /* 9.1 step 4 is implicit in  drbg_sec_strength */
1564 
1565         if (!drbg->core) {
1566                 drbg->core = &drbg_cores[coreref];
1567                 drbg->pr = pr;
1568                 drbg->seeded = false;
1569                 drbg->reseed_threshold = drbg_max_requests(drbg);
1570 
1571                 ret = drbg_alloc_state(drbg);
1572                 if (ret)
1573                         goto unlock;
1574 
1575                 ret = drbg_prepare_hrng(drbg);
1576                 if (ret)
1577                         goto free_everything;
1578 
1579                 if (IS_ERR(drbg->jent)) {
1580                         ret = PTR_ERR(drbg->jent);
1581                         drbg->jent = NULL;
1582                         if (fips_enabled || ret != -ENOENT)
1583                                 goto free_everything;
1584                         pr_info("DRBG: Continuing without Jitter RNG\n");
1585                 }
1586 
1587                 reseed = false;
1588         }
1589 
1590         ret = drbg_seed(drbg, pers, reseed);
1591 
1592         if (ret && !reseed)
1593                 goto free_everything;
1594 
1595         mutex_unlock(&drbg->drbg_mutex);
1596         return ret;
1597 
1598 unlock:
1599         mutex_unlock(&drbg->drbg_mutex);
1600         return ret;
1601 
1602 free_everything:
1603         mutex_unlock(&drbg->drbg_mutex);
1604         drbg_uninstantiate(drbg);
1605         return ret;
1606 }
1607 
1608 /*
1609  * DRBG uninstantiate function as required by SP800-90A - this function
1610  * frees all buffers and the DRBG handle
1611  *
1612  * @drbg DRBG state handle
1613  *
1614  * return
1615  *      0 on success
1616  */
1617 static int drbg_uninstantiate(struct drbg_state *drbg)
1618 {
1619         if (drbg->random_ready.func) {
1620                 del_random_ready_callback(&drbg->random_ready);
1621                 cancel_work_sync(&drbg->seed_work);
1622                 crypto_free_rng(drbg->jent);
1623                 drbg->jent = NULL;
1624         }
1625 
1626         if (drbg->d_ops)
1627                 drbg->d_ops->crypto_fini(drbg);
1628         drbg_dealloc_state(drbg);
1629         /* no scrubbing of test_data -- this shall survive an uninstantiate */
1630         return 0;
1631 }
1632 
1633 /*
1634  * Helper function for setting the test data in the DRBG
1635  *
1636  * @drbg DRBG state handle
1637  * @data test data
1638  * @len test data length
1639  */
1640 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
1641                                    const u8 *data, unsigned int len)
1642 {
1643         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1644 
1645         mutex_lock(&drbg->drbg_mutex);
1646         drbg_string_fill(&drbg->test_data, data, len);
1647         mutex_unlock(&drbg->drbg_mutex);
1648 }
1649 
1650 /***************************************************************
1651  * Kernel crypto API cipher invocations requested by DRBG
1652  ***************************************************************/
1653 
1654 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1655 struct sdesc {
1656         struct shash_desc shash;
1657         char ctx[];
1658 };
1659 
1660 static int drbg_init_hash_kernel(struct drbg_state *drbg)
1661 {
1662         struct sdesc *sdesc;
1663         struct crypto_shash *tfm;
1664 
1665         tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1666         if (IS_ERR(tfm)) {
1667                 pr_info("DRBG: could not allocate digest TFM handle: %s\n",
1668                                 drbg->core->backend_cra_name);
1669                 return PTR_ERR(tfm);
1670         }
1671         BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1672         sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1673                         GFP_KERNEL);
1674         if (!sdesc) {
1675                 crypto_free_shash(tfm);
1676                 return -ENOMEM;
1677         }
1678 
1679         sdesc->shash.tfm = tfm;
1680         drbg->priv_data = sdesc;
1681 
1682         return crypto_shash_alignmask(tfm);
1683 }
1684 
1685 static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1686 {
1687         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1688         if (sdesc) {
1689                 crypto_free_shash(sdesc->shash.tfm);
1690                 kzfree(sdesc);
1691         }
1692         drbg->priv_data = NULL;
1693         return 0;
1694 }
1695 
1696 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
1697                                   const unsigned char *key)
1698 {
1699         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1700 
1701         crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
1702 }
1703 
1704 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
1705                            const struct list_head *in)
1706 {
1707         struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1708         struct drbg_string *input = NULL;
1709 
1710         crypto_shash_init(&sdesc->shash);
1711         list_for_each_entry(input, in, list)
1712                 crypto_shash_update(&sdesc->shash, input->buf, input->len);
1713         return crypto_shash_final(&sdesc->shash, outval);
1714 }
1715 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1716 
1717 #ifdef CONFIG_CRYPTO_DRBG_CTR
1718 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1719 {
1720         struct crypto_cipher *tfm =
1721                 (struct crypto_cipher *)drbg->priv_data;
1722         if (tfm)
1723                 crypto_free_cipher(tfm);
1724         drbg->priv_data = NULL;
1725 
1726         if (drbg->ctr_handle)
1727                 crypto_free_skcipher(drbg->ctr_handle);
1728         drbg->ctr_handle = NULL;
1729 
1730         if (drbg->ctr_req)
1731                 skcipher_request_free(drbg->ctr_req);
1732         drbg->ctr_req = NULL;
1733 
1734         kfree(drbg->outscratchpadbuf);
1735         drbg->outscratchpadbuf = NULL;
1736 
1737         return 0;
1738 }
1739 
1740 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1741 {
1742         struct crypto_cipher *tfm;
1743         struct crypto_skcipher *sk_tfm;
1744         struct skcipher_request *req;
1745         unsigned int alignmask;
1746         char ctr_name[CRYPTO_MAX_ALG_NAME];
1747 
1748         tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1749         if (IS_ERR(tfm)) {
1750                 pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1751                                 drbg->core->backend_cra_name);
1752                 return PTR_ERR(tfm);
1753         }
1754         BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1755         drbg->priv_data = tfm;
1756 
1757         if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1758             drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1759                 drbg_fini_sym_kernel(drbg);
1760                 return -EINVAL;
1761         }
1762         sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1763         if (IS_ERR(sk_tfm)) {
1764                 pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1765                                 ctr_name);
1766                 drbg_fini_sym_kernel(drbg);
1767                 return PTR_ERR(sk_tfm);
1768         }
1769         drbg->ctr_handle = sk_tfm;
1770         crypto_init_wait(&drbg->ctr_wait);
1771 
1772         req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1773         if (!req) {
1774                 pr_info("DRBG: could not allocate request queue\n");
1775                 drbg_fini_sym_kernel(drbg);
1776                 return -ENOMEM;
1777         }
1778         drbg->ctr_req = req;
1779         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
1780                                                 CRYPTO_TFM_REQ_MAY_SLEEP,
1781                                         crypto_req_done, &drbg->ctr_wait);
1782 
1783         alignmask = crypto_skcipher_alignmask(sk_tfm);
1784         drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
1785                                          GFP_KERNEL);
1786         if (!drbg->outscratchpadbuf) {
1787                 drbg_fini_sym_kernel(drbg);
1788                 return -ENOMEM;
1789         }
1790         drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
1791                                               alignmask + 1);
1792 
1793         sg_init_table(&drbg->sg_in, 1);
1794         sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1795 
1796         return alignmask;
1797 }
1798 
1799 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1800                                  const unsigned char *key)
1801 {
1802         struct crypto_cipher *tfm =
1803                 (struct crypto_cipher *)drbg->priv_data;
1804 
1805         crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1806 }
1807 
1808 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1809                           const struct drbg_string *in)
1810 {
1811         struct crypto_cipher *tfm =
1812                 (struct crypto_cipher *)drbg->priv_data;
1813 
1814         /* there is only component in *in */
1815         BUG_ON(in->len < drbg_blocklen(drbg));
1816         crypto_cipher_encrypt_one(tfm, outval, in->buf);
1817         return 0;
1818 }
1819 
1820 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1821                               u8 *inbuf, u32 inlen,
1822                               u8 *outbuf, u32 outlen)
1823 {
1824         struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;
1825         u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN);
1826         int ret;
1827 
1828         if (inbuf) {
1829                 /* Use caller-provided input buffer */
1830                 sg_set_buf(sg_in, inbuf, inlen);
1831         } else {
1832                 /* Use scratchpad for in-place operation */
1833                 inlen = scratchpad_use;
1834                 memset(drbg->outscratchpad, 0, scratchpad_use);
1835                 sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use);
1836         }
1837 
1838         while (outlen) {
1839                 u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1840 
1841                 /* Output buffer may not be valid for SGL, use scratchpad */
1842                 skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out,
1843                                            cryptlen, drbg->V);
1844                 ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
1845                                         &drbg->ctr_wait);
1846                 if (ret)
1847                         goto out;
1848 
1849                 crypto_init_wait(&drbg->ctr_wait);
1850 
1851                 memcpy(outbuf, drbg->outscratchpad, cryptlen);
1852                 memzero_explicit(drbg->outscratchpad, cryptlen);
1853 
1854                 outlen -= cryptlen;
1855                 outbuf += cryptlen;
1856         }
1857         ret = 0;
1858 
1859 out:
1860         return ret;
1861 }
1862 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1863 
1864 /***************************************************************
1865  * Kernel crypto API interface to register DRBG
1866  ***************************************************************/
1867 
1868 /*
1869  * Look up the DRBG flags by given kernel crypto API cra_name
1870  * The code uses the drbg_cores definition to do this
1871  *
1872  * @cra_name kernel crypto API cra_name
1873  * @coreref reference to integer which is filled with the pointer to
1874  *  the applicable core
1875  * @pr reference for setting prediction resistance
1876  *
1877  * return: flags
1878  */
1879 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1880                                          int *coreref, bool *pr)
1881 {
1882         int i = 0;
1883         size_t start = 0;
1884         int len = 0;
1885 
1886         *pr = true;
1887         /* disassemble the names */
1888         if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1889                 start = 10;
1890                 *pr = false;
1891         } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1892                 start = 8;
1893         } else {
1894                 return;
1895         }
1896 
1897         /* remove the first part */
1898         len = strlen(cra_driver_name) - start;
1899         for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1900                 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1901                             len)) {
1902                         *coreref = i;
1903                         return;
1904                 }
1905         }
1906 }
1907 
1908 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1909 {
1910         struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1911 
1912         mutex_init(&drbg->drbg_mutex);
1913 
1914         return 0;
1915 }
1916 
1917 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1918 {
1919         drbg_uninstantiate(crypto_tfm_ctx(tfm));
1920 }
1921 
1922 /*
1923  * Generate random numbers invoked by the kernel crypto API:
1924  * The API of the kernel crypto API is extended as follows:
1925  *
1926  * src is additional input supplied to the RNG.
1927  * slen is the length of src.
1928  * dst is the output buffer where random data is to be stored.
1929  * dlen is the length of dst.
1930  */
1931 static int drbg_kcapi_random(struct crypto_rng *tfm,
1932                              const u8 *src, unsigned int slen,
1933                              u8 *dst, unsigned int dlen)
1934 {
1935         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1936         struct drbg_string *addtl = NULL;
1937         struct drbg_string string;
1938 
1939         if (slen) {
1940                 /* linked list variable is now local to allow modification */
1941                 drbg_string_fill(&string, src, slen);
1942                 addtl = &string;
1943         }
1944 
1945         return drbg_generate_long(drbg, dst, dlen, addtl);
1946 }
1947 
1948 /*
1949  * Seed the DRBG invoked by the kernel crypto API
1950  */
1951 static int drbg_kcapi_seed(struct crypto_rng *tfm,
1952                            const u8 *seed, unsigned int slen)
1953 {
1954         struct drbg_state *drbg = crypto_rng_ctx(tfm);
1955         struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1956         bool pr = false;
1957         struct drbg_string string;
1958         struct drbg_string *seed_string = NULL;
1959         int coreref = 0;
1960 
1961         drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1962                               &pr);
1963         if (0 < slen) {
1964                 drbg_string_fill(&string, seed, slen);
1965                 seed_string = &string;
1966         }
1967 
1968         return drbg_instantiate(drbg, seed_string, coreref, pr);
1969 }
1970 
1971 /***************************************************************
1972  * Kernel module: code to load the module
1973  ***************************************************************/
1974 
1975 /*
1976  * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1977  * of the error handling.
1978  *
1979  * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1980  * as seed source of get_random_bytes does not fail.
1981  *
1982  * Note 2: There is no sensible way of testing the reseed counter
1983  * enforcement, so skip it.
1984  */
1985 static inline int __init drbg_healthcheck_sanity(void)
1986 {
1987         int len = 0;
1988 #define OUTBUFLEN 16
1989         unsigned char buf[OUTBUFLEN];
1990         struct drbg_state *drbg = NULL;
1991         int ret = -EFAULT;
1992         int rc = -EFAULT;
1993         bool pr = false;
1994         int coreref = 0;
1995         struct drbg_string addtl;
1996         size_t max_addtllen, max_request_bytes;
1997 
1998         /* only perform test in FIPS mode */
1999         if (!fips_enabled)
2000                 return 0;
2001 
2002 #ifdef CONFIG_CRYPTO_DRBG_CTR
2003         drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
2004 #elif defined CONFIG_CRYPTO_DRBG_HASH
2005         drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
2006 #else
2007         drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
2008 #endif
2009 
2010         drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
2011         if (!drbg)
2012                 return -ENOMEM;
2013 
2014         mutex_init(&drbg->drbg_mutex);
2015         drbg->core = &drbg_cores[coreref];
2016         drbg->reseed_threshold = drbg_max_requests(drbg);
2017 
2018         /*
2019          * if the following tests fail, it is likely that there is a buffer
2020          * overflow as buf is much smaller than the requested or provided
2021          * string lengths -- in case the error handling does not succeed
2022          * we may get an OOPS. And we want to get an OOPS as this is a
2023          * grave bug.
2024          */
2025 
2026         max_addtllen = drbg_max_addtl(drbg);
2027         max_request_bytes = drbg_max_request_bytes(drbg);
2028         drbg_string_fill(&addtl, buf, max_addtllen + 1);
2029         /* overflow addtllen with additonal info string */
2030         len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
2031         BUG_ON(0 < len);
2032         /* overflow max_bits */
2033         len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
2034         BUG_ON(0 < len);
2035 
2036         /* overflow max addtllen with personalization string */
2037         ret = drbg_seed(drbg, &addtl, false);
2038         BUG_ON(0 == ret);
2039         /* all tests passed */
2040         rc = 0;
2041 
2042         pr_devel("DRBG: Sanity tests for failure code paths successfully "
2043                  "completed\n");
2044 
2045         kfree(drbg);
2046         return rc;
2047 }
2048 
2049 static struct rng_alg drbg_algs[22];
2050 
2051 /*
2052  * Fill the array drbg_algs used to register the different DRBGs
2053  * with the kernel crypto API. To fill the array, the information
2054  * from drbg_cores[] is used.
2055  */
2056 static inline void __init drbg_fill_array(struct rng_alg *alg,
2057                                           const struct drbg_core *core, int pr)
2058 {
2059         int pos = 0;
2060         static int priority = 200;
2061 
2062         memcpy(alg->base.cra_name, "stdrng", 6);
2063         if (pr) {
2064                 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
2065                 pos = 8;
2066         } else {
2067                 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
2068                 pos = 10;
2069         }
2070         memcpy(alg->base.cra_driver_name + pos, core->cra_name,
2071                strlen(core->cra_name));
2072 
2073         alg->base.cra_priority = priority;
2074         priority++;
2075         /*
2076          * If FIPS mode enabled, the selected DRBG shall have the
2077          * highest cra_priority over other stdrng instances to ensure
2078          * it is selected.
2079          */
2080         if (fips_enabled)
2081                 alg->base.cra_priority += 200;
2082 
2083         alg->base.cra_ctxsize   = sizeof(struct drbg_state);
2084         alg->base.cra_module    = THIS_MODULE;
2085         alg->base.cra_init      = drbg_kcapi_init;
2086         alg->base.cra_exit      = drbg_kcapi_cleanup;
2087         alg->generate           = drbg_kcapi_random;
2088         alg->seed               = drbg_kcapi_seed;
2089         alg->set_ent            = drbg_kcapi_set_entropy;
2090         alg->seedsize           = 0;
2091 }
2092 
2093 static int __init drbg_init(void)
2094 {
2095         unsigned int i = 0; /* pointer to drbg_algs */
2096         unsigned int j = 0; /* pointer to drbg_cores */
2097         int ret;
2098 
2099         ret = drbg_healthcheck_sanity();
2100         if (ret)
2101                 return ret;
2102 
2103         if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2104                 pr_info("DRBG: Cannot register all DRBG types"
2105                         "(slots needed: %zu, slots available: %zu)\n",
2106                         ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2107                 return -EFAULT;
2108         }
2109 
2110         /*
2111          * each DRBG definition can be used with PR and without PR, thus
2112          * we instantiate each DRBG in drbg_cores[] twice.
2113          *
2114          * As the order of placing them into the drbg_algs array matters
2115          * (the later DRBGs receive a higher cra_priority) we register the
2116          * prediction resistance DRBGs first as the should not be too
2117          * interesting.
2118          */
2119         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2120                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2121         for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2122                 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2123         return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2124 }
2125 
2126 static void __exit drbg_exit(void)
2127 {
2128         crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2129 }
2130 
2131 subsys_initcall(drbg_init);
2132 module_exit(drbg_exit);
2133 #ifndef CRYPTO_DRBG_HASH_STRING
2134 #define CRYPTO_DRBG_HASH_STRING ""
2135 #endif
2136 #ifndef CRYPTO_DRBG_HMAC_STRING
2137 #define CRYPTO_DRBG_HMAC_STRING ""
2138 #endif
2139 #ifndef CRYPTO_DRBG_CTR_STRING
2140 #define CRYPTO_DRBG_CTR_STRING ""
2141 #endif
2142 MODULE_LICENSE("GPL");
2143 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2144 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2145                    "using following cores: "
2146                    CRYPTO_DRBG_HASH_STRING
2147                    CRYPTO_DRBG_HMAC_STRING
2148                    CRYPTO_DRBG_CTR_STRING);
2149 MODULE_ALIAS_CRYPTO("stdrng");
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root/crypto/drbg.c

DEFINITIONS
