linux/crypto/drbg.c
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   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 */
 116static 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
 194static 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 */
 208static 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))
 231static 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 "
 248MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
 249MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
 250MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
 251MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
 252MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
 253MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");
 254
 255static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
 256                                 const unsigned char *key);
 257static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
 258                          const struct drbg_string *in);
 259static int drbg_init_sym_kernel(struct drbg_state *drbg);
 260static int drbg_fini_sym_kernel(struct drbg_state *drbg);
 261static 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 */
 268static 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 */
 346static 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
 458out:
 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 */
 480static 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
 531out:
 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 */
 543static 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
 571static 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)
 584static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
 585                           const struct list_head *in);
 586static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
 587                                  const unsigned char *key);
 588static int drbg_init_hash_kernel(struct drbg_state *drbg);
 589static 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 "
 594MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
 595MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
 596MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
 597MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
 598MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
 599MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
 600MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
 601MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
 602
 603/* update function of HMAC DRBG as defined in 10.1.2.2 */
 604static 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 */
 656static 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
 700static 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 "
 714MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
 715MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
 716MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
 717MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
 718MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
 719MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
 720MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
 721MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
 722
 723/*
 724 * Increment buffer
 725 *
 726 * @dst buffer to increment
 727 * @add value to add
 728 */
 729static 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 */
 771static 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
 804out:
 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 */
 810static 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
 847out:
 848        memset(drbg->scratchpad, 0, drbg_statelen(drbg));
 849        return ret;
 850}
 851
 852/* processing of additional information string for Hash DRBG */
 853static 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
 879out:
 880        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 881        return ret;
 882}
 883
 884/* Hashgen defined in 10.1.1.4 */
 885static 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
 919out:
 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 */
 926static 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
 967out:
 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 */
 976static 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
 988static 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
1003static 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 */
1051static 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 */
1132static 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 */
1151static 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
1216fini:
1217        drbg->d_ops->crypto_fini(drbg);
1218err:
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 */
1243static 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;
1358err:
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 */
1370static 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
1391static 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
1399static 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 */
1455static 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
1508unlock:
1509        mutex_unlock(&drbg->drbg_mutex);
1510        return ret;
1511
1512free_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 */
1527static 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 */
1550static 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)
1565struct sdesc {
1566        struct shash_desc shash;
1567        char ctx[];
1568};
1569
1570static 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
1596static 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
1607static 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
1615static 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
1629static 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
1654static 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
1664static 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
1727static 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
1736static 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
1748static 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;
1753        int ret;
1754
1755        sg_init_one(&sg_in, inbuf, inlen);
1756
1757        while (outlen) {
1758                u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1759                struct scatterlist sg_out;
1760
1761                /* Output buffer may not be valid for SGL, use scratchpad */
1762                sg_init_one(&sg_out, drbg->outscratchpad, cryptlen);
1763                skcipher_request_set_crypt(drbg->ctr_req, &sg_in, &sg_out,
1764                                           cryptlen, drbg->V);
1765                ret = crypto_skcipher_encrypt(drbg->ctr_req);
1766                switch (ret) {
1767                case 0:
1768                        break;
1769                case -EINPROGRESS:
1770                case -EBUSY:
1771                        ret = wait_for_completion_interruptible(
1772                                &drbg->ctr_completion);
1773                        if (!ret && !drbg->ctr_async_err) {
1774                                reinit_completion(&drbg->ctr_completion);
1775                                break;
1776                        }
1777                default:
1778                        goto out;
1779                }
1780                init_completion(&drbg->ctr_completion);
1781
1782                memcpy(outbuf, drbg->outscratchpad, cryptlen);
1783
1784                outlen -= cryptlen;
1785        }
1786        ret = 0;
1787
1788out:
1789        memzero_explicit(drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1790        return ret;
1791}
1792#endif /* CONFIG_CRYPTO_DRBG_CTR */
1793
1794/***************************************************************
1795 * Kernel crypto API interface to register DRBG
1796 ***************************************************************/
1797
1798/*
1799 * Look up the DRBG flags by given kernel crypto API cra_name
1800 * The code uses the drbg_cores definition to do this
1801 *
1802 * @cra_name kernel crypto API cra_name
1803 * @coreref reference to integer which is filled with the pointer to
1804 *  the applicable core
1805 * @pr reference for setting prediction resistance
1806 *
1807 * return: flags
1808 */
1809static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1810                                         int *coreref, bool *pr)
1811{
1812        int i = 0;
1813        size_t start = 0;
1814        int len = 0;
1815
1816        *pr = true;
1817        /* disassemble the names */
1818        if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1819                start = 10;
1820                *pr = false;
1821        } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1822                start = 8;
1823        } else {
1824                return;
1825        }
1826
1827        /* remove the first part */
1828        len = strlen(cra_driver_name) - start;
1829        for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1830                if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1831                            len)) {
1832                        *coreref = i;
1833                        return;
1834                }
1835        }
1836}
1837
1838static int drbg_kcapi_init(struct crypto_tfm *tfm)
1839{
1840        struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1841
1842        mutex_init(&drbg->drbg_mutex);
1843
1844        return 0;
1845}
1846
1847static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1848{
1849        drbg_uninstantiate(crypto_tfm_ctx(tfm));
1850}
1851
1852/*
1853 * Generate random numbers invoked by the kernel crypto API:
1854 * The API of the kernel crypto API is extended as follows:
1855 *
1856 * src is additional input supplied to the RNG.
1857 * slen is the length of src.
1858 * dst is the output buffer where random data is to be stored.
1859 * dlen is the length of dst.
1860 */
1861static int drbg_kcapi_random(struct crypto_rng *tfm,
1862                             const u8 *src, unsigned int slen,
1863                             u8 *dst, unsigned int dlen)
1864{
1865        struct drbg_state *drbg = crypto_rng_ctx(tfm);
1866        struct drbg_string *addtl = NULL;
1867        struct drbg_string string;
1868
1869        if (slen) {
1870                /* linked list variable is now local to allow modification */
1871                drbg_string_fill(&string, src, slen);
1872                addtl = &string;
1873        }
1874
1875        return drbg_generate_long(drbg, dst, dlen, addtl);
1876}
1877
1878/*
1879 * Seed the DRBG invoked by the kernel crypto API
1880 */
1881static int drbg_kcapi_seed(struct crypto_rng *tfm,
1882                           const u8 *seed, unsigned int slen)
1883{
1884        struct drbg_state *drbg = crypto_rng_ctx(tfm);
1885        struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1886        bool pr = false;
1887        struct drbg_string string;
1888        struct drbg_string *seed_string = NULL;
1889        int coreref = 0;
1890
1891        drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1892                              &pr);
1893        if (0 < slen) {
1894                drbg_string_fill(&string, seed, slen);
1895                seed_string = &string;
1896        }
1897
1898        return drbg_instantiate(drbg, seed_string, coreref, pr);
1899}
1900
1901/***************************************************************
1902 * Kernel module: code to load the module
1903 ***************************************************************/
1904
1905/*
1906 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1907 * of the error handling.
1908 *
1909 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1910 * as seed source of get_random_bytes does not fail.
1911 *
1912 * Note 2: There is no sensible way of testing the reseed counter
1913 * enforcement, so skip it.
1914 */
1915static inline int __init drbg_healthcheck_sanity(void)
1916{
1917        int len = 0;
1918#define OUTBUFLEN 16
1919        unsigned char buf[OUTBUFLEN];
1920        struct drbg_state *drbg = NULL;
1921        int ret = -EFAULT;
1922        int rc = -EFAULT;
1923        bool pr = false;
1924        int coreref = 0;
1925        struct drbg_string addtl;
1926        size_t max_addtllen, max_request_bytes;
1927
1928        /* only perform test in FIPS mode */
1929        if (!fips_enabled)
1930                return 0;
1931
1932#ifdef CONFIG_CRYPTO_DRBG_CTR
1933        drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1934#elif defined CONFIG_CRYPTO_DRBG_HASH
1935        drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1936#else
1937        drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1938#endif
1939
1940        drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1941        if (!drbg)
1942                return -ENOMEM;
1943
1944        mutex_init(&drbg->drbg_mutex);
1945        drbg->core = &drbg_cores[coreref];
1946        drbg->reseed_threshold = drbg_max_requests(drbg);
1947
1948        /*
1949         * if the following tests fail, it is likely that there is a buffer
1950         * overflow as buf is much smaller than the requested or provided
1951         * string lengths -- in case the error handling does not succeed
1952         * we may get an OOPS. And we want to get an OOPS as this is a
1953         * grave bug.
1954         */
1955
1956        max_addtllen = drbg_max_addtl(drbg);
1957        max_request_bytes = drbg_max_request_bytes(drbg);
1958        drbg_string_fill(&addtl, buf, max_addtllen + 1);
1959        /* overflow addtllen with additonal info string */
1960        len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1961        BUG_ON(0 < len);
1962        /* overflow max_bits */
1963        len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1964        BUG_ON(0 < len);
1965
1966        /* overflow max addtllen with personalization string */
1967        ret = drbg_seed(drbg, &addtl, false);
1968        BUG_ON(0 == ret);
1969        /* all tests passed */
1970        rc = 0;
1971
1972        pr_devel("DRBG: Sanity tests for failure code paths successfully "
1973                 "completed\n");
1974
1975        kfree(drbg);
1976        return rc;
1977}
1978
1979static struct rng_alg drbg_algs[22];
1980
1981/*
1982 * Fill the array drbg_algs used to register the different DRBGs
1983 * with the kernel crypto API. To fill the array, the information
1984 * from drbg_cores[] is used.
1985 */
1986static inline void __init drbg_fill_array(struct rng_alg *alg,
1987                                          const struct drbg_core *core, int pr)
1988{
1989        int pos = 0;
1990        static int priority = 200;
1991
1992        memcpy(alg->base.cra_name, "stdrng", 6);
1993        if (pr) {
1994                memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
1995                pos = 8;
1996        } else {
1997                memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
1998                pos = 10;
1999        }
2000        memcpy(alg->base.cra_driver_name + pos, core->cra_name,
2001               strlen(core->cra_name));
2002
2003        alg->base.cra_priority = priority;
2004        priority++;
2005        /*
2006         * If FIPS mode enabled, the selected DRBG shall have the
2007         * highest cra_priority over other stdrng instances to ensure
2008         * it is selected.
2009         */
2010        if (fips_enabled)
2011                alg->base.cra_priority += 200;
2012
2013        alg->base.cra_ctxsize   = sizeof(struct drbg_state);
2014        alg->base.cra_module    = THIS_MODULE;
2015        alg->base.cra_init      = drbg_kcapi_init;
2016        alg->base.cra_exit      = drbg_kcapi_cleanup;
2017        alg->generate           = drbg_kcapi_random;
2018        alg->seed               = drbg_kcapi_seed;
2019        alg->set_ent            = drbg_kcapi_set_entropy;
2020        alg->seedsize           = 0;
2021}
2022
2023static int __init drbg_init(void)
2024{
2025        unsigned int i = 0; /* pointer to drbg_algs */
2026        unsigned int j = 0; /* pointer to drbg_cores */
2027        int ret;
2028
2029        ret = drbg_healthcheck_sanity();
2030        if (ret)
2031                return ret;
2032
2033        if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2034                pr_info("DRBG: Cannot register all DRBG types"
2035                        "(slots needed: %zu, slots available: %zu)\n",
2036                        ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2037                return -EFAULT;
2038        }
2039
2040        /*
2041         * each DRBG definition can be used with PR and without PR, thus
2042         * we instantiate each DRBG in drbg_cores[] twice.
2043         *
2044         * As the order of placing them into the drbg_algs array matters
2045         * (the later DRBGs receive a higher cra_priority) we register the
2046         * prediction resistance DRBGs first as the should not be too
2047         * interesting.
2048         */
2049        for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2050                drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2051        for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2052                drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2053        return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2054}
2055
2056static void __exit drbg_exit(void)
2057{
2058        crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2059}
2060
2061module_init(drbg_init);
2062module_exit(drbg_exit);
2063#ifndef CRYPTO_DRBG_HASH_STRING
2064#define CRYPTO_DRBG_HASH_STRING ""
2065#endif
2066#ifndef CRYPTO_DRBG_HMAC_STRING
2067#define CRYPTO_DRBG_HMAC_STRING ""
2068#endif
2069#ifndef CRYPTO_DRBG_CTR_STRING
2070#define CRYPTO_DRBG_CTR_STRING ""
2071#endif
2072MODULE_LICENSE("GPL");
2073MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2074MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2075                   "using following cores: "
2076                   CRYPTO_DRBG_HASH_STRING
2077                   CRYPTO_DRBG_HMAC_STRING
2078                   CRYPTO_DRBG_CTR_STRING);
2079MODULE_ALIAS_CRYPTO("stdrng");
2080