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_OUTSCRATCHLEN 256
 265
 266/* BCC function for CTR DRBG as defined in 10.4.3 */
 267static int drbg_ctr_bcc(struct drbg_state *drbg,
 268                        unsigned char *out, const unsigned char *key,
 269                        struct list_head *in)
 270{
 271        int ret = 0;
 272        struct drbg_string *curr = NULL;
 273        struct drbg_string data;
 274        short cnt = 0;
 275
 276        drbg_string_fill(&data, out, drbg_blocklen(drbg));
 277
 278        /* 10.4.3 step 2 / 4 */
 279        drbg_kcapi_symsetkey(drbg, key);
 280        list_for_each_entry(curr, in, list) {
 281                const unsigned char *pos = curr->buf;
 282                size_t len = curr->len;
 283                /* 10.4.3 step 4.1 */
 284                while (len) {
 285                        /* 10.4.3 step 4.2 */
 286                        if (drbg_blocklen(drbg) == cnt) {
 287                                cnt = 0;
 288                                ret = drbg_kcapi_sym(drbg, out, &data);
 289                                if (ret)
 290                                        return ret;
 291                        }
 292                        out[cnt] ^= *pos;
 293                        pos++;
 294                        cnt++;
 295                        len--;
 296                }
 297        }
 298        /* 10.4.3 step 4.2 for last block */
 299        if (cnt)
 300                ret = drbg_kcapi_sym(drbg, out, &data);
 301
 302        return ret;
 303}
 304
 305/*
 306 * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
 307 * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
 308 * the scratchpad is used as follows:
 309 * drbg_ctr_update:
 310 *      temp
 311 *              start: drbg->scratchpad
 312 *              length: drbg_statelen(drbg) + drbg_blocklen(drbg)
 313 *                      note: the cipher writing into this variable works
 314 *                      blocklen-wise. Now, when the statelen is not a multiple
 315 *                      of blocklen, the generateion loop below "spills over"
 316 *                      by at most blocklen. Thus, we need to give sufficient
 317 *                      memory.
 318 *      df_data
 319 *              start: drbg->scratchpad +
 320 *                              drbg_statelen(drbg) + drbg_blocklen(drbg)
 321 *              length: drbg_statelen(drbg)
 322 *
 323 * drbg_ctr_df:
 324 *      pad
 325 *              start: df_data + drbg_statelen(drbg)
 326 *              length: drbg_blocklen(drbg)
 327 *      iv
 328 *              start: pad + drbg_blocklen(drbg)
 329 *              length: drbg_blocklen(drbg)
 330 *      temp
 331 *              start: iv + drbg_blocklen(drbg)
 332 *              length: drbg_satelen(drbg) + drbg_blocklen(drbg)
 333 *                      note: temp is the buffer that the BCC function operates
 334 *                      on. BCC operates blockwise. drbg_statelen(drbg)
 335 *                      is sufficient when the DRBG state length is a multiple
 336 *                      of the block size. For AES192 (and maybe other ciphers)
 337 *                      this is not correct and the length for temp is
 338 *                      insufficient (yes, that also means for such ciphers,
 339 *                      the final output of all BCC rounds are truncated).
 340 *                      Therefore, add drbg_blocklen(drbg) to cover all
 341 *                      possibilities.
 342 */
 343
 344/* Derivation Function for CTR DRBG as defined in 10.4.2 */
 345static int drbg_ctr_df(struct drbg_state *drbg,
 346                       unsigned char *df_data, size_t bytes_to_return,
 347                       struct list_head *seedlist)
 348{
 349        int ret = -EFAULT;
 350        unsigned char L_N[8];
 351        /* S3 is input */
 352        struct drbg_string S1, S2, S4, cipherin;
 353        LIST_HEAD(bcc_list);
 354        unsigned char *pad = df_data + drbg_statelen(drbg);
 355        unsigned char *iv = pad + drbg_blocklen(drbg);
 356        unsigned char *temp = iv + drbg_blocklen(drbg);
 357        size_t padlen = 0;
 358        unsigned int templen = 0;
 359        /* 10.4.2 step 7 */
 360        unsigned int i = 0;
 361        /* 10.4.2 step 8 */
 362        const unsigned char *K = (unsigned char *)
 363                           "\x00\x01\x02\x03\x04\x05\x06\x07"
 364                           "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
 365                           "\x10\x11\x12\x13\x14\x15\x16\x17"
 366                           "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
 367        unsigned char *X;
 368        size_t generated_len = 0;
 369        size_t inputlen = 0;
 370        struct drbg_string *seed = NULL;
 371
 372        memset(pad, 0, drbg_blocklen(drbg));
 373        memset(iv, 0, drbg_blocklen(drbg));
 374
 375        /* 10.4.2 step 1 is implicit as we work byte-wise */
 376
 377        /* 10.4.2 step 2 */
 378        if ((512/8) < bytes_to_return)
 379                return -EINVAL;
 380
 381        /* 10.4.2 step 2 -- calculate the entire length of all input data */
 382        list_for_each_entry(seed, seedlist, list)
 383                inputlen += seed->len;
 384        drbg_cpu_to_be32(inputlen, &L_N[0]);
 385
 386        /* 10.4.2 step 3 */
 387        drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
 388
 389        /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
 390        padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
 391        /* wrap the padlen appropriately */
 392        if (padlen)
 393                padlen = drbg_blocklen(drbg) - padlen;
 394        /*
 395         * pad / padlen contains the 0x80 byte and the following zero bytes.
 396         * As the calculated padlen value only covers the number of zero
 397         * bytes, this value has to be incremented by one for the 0x80 byte.
 398         */
 399        padlen++;
 400        pad[0] = 0x80;
 401
 402        /* 10.4.2 step 4 -- first fill the linked list and then order it */
 403        drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
 404        list_add_tail(&S1.list, &bcc_list);
 405        drbg_string_fill(&S2, L_N, sizeof(L_N));
 406        list_add_tail(&S2.list, &bcc_list);
 407        list_splice_tail(seedlist, &bcc_list);
 408        drbg_string_fill(&S4, pad, padlen);
 409        list_add_tail(&S4.list, &bcc_list);
 410
 411        /* 10.4.2 step 9 */
 412        while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
 413                /*
 414                 * 10.4.2 step 9.1 - the padding is implicit as the buffer
 415                 * holds zeros after allocation -- even the increment of i
 416                 * is irrelevant as the increment remains within length of i
 417                 */
 418                drbg_cpu_to_be32(i, iv);
 419                /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
 420                ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
 421                if (ret)
 422                        goto out;
 423                /* 10.4.2 step 9.3 */
 424                i++;
 425                templen += drbg_blocklen(drbg);
 426        }
 427
 428        /* 10.4.2 step 11 */
 429        X = temp + (drbg_keylen(drbg));
 430        drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
 431
 432        /* 10.4.2 step 12: overwriting of outval is implemented in next step */
 433
 434        /* 10.4.2 step 13 */
 435        drbg_kcapi_symsetkey(drbg, temp);
 436        while (generated_len < bytes_to_return) {
 437                short blocklen = 0;
 438                /*
 439                 * 10.4.2 step 13.1: the truncation of the key length is
 440                 * implicit as the key is only drbg_blocklen in size based on
 441                 * the implementation of the cipher function callback
 442                 */
 443                ret = drbg_kcapi_sym(drbg, X, &cipherin);
 444                if (ret)
 445                        goto out;
 446                blocklen = (drbg_blocklen(drbg) <
 447                                (bytes_to_return - generated_len)) ?
 448                            drbg_blocklen(drbg) :
 449                                (bytes_to_return - generated_len);
 450                /* 10.4.2 step 13.2 and 14 */
 451                memcpy(df_data + generated_len, X, blocklen);
 452                generated_len += blocklen;
 453        }
 454
 455        ret = 0;
 456
 457out:
 458        memset(iv, 0, drbg_blocklen(drbg));
 459        memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 460        memset(pad, 0, drbg_blocklen(drbg));
 461        return ret;
 462}
 463
 464/*
 465 * update function of CTR DRBG as defined in 10.2.1.2
 466 *
 467 * The reseed variable has an enhanced meaning compared to the update
 468 * functions of the other DRBGs as follows:
 469 * 0 => initial seed from initialization
 470 * 1 => reseed via drbg_seed
 471 * 2 => first invocation from drbg_ctr_update when addtl is present. In
 472 *      this case, the df_data scratchpad is not deleted so that it is
 473 *      available for another calls to prevent calling the DF function
 474 *      again.
 475 * 3 => second invocation from drbg_ctr_update. When the update function
 476 *      was called with addtl, the df_data memory already contains the
 477 *      DFed addtl information and we do not need to call DF again.
 478 */
 479static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
 480                           int reseed)
 481{
 482        int ret = -EFAULT;
 483        /* 10.2.1.2 step 1 */
 484        unsigned char *temp = drbg->scratchpad;
 485        unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
 486                                 drbg_blocklen(drbg);
 487
 488        if (3 > reseed)
 489                memset(df_data, 0, drbg_statelen(drbg));
 490
 491        if (!reseed) {
 492                /*
 493                 * The DRBG uses the CTR mode of the underlying AES cipher. The
 494                 * CTR mode increments the counter value after the AES operation
 495                 * but SP800-90A requires that the counter is incremented before
 496                 * the AES operation. Hence, we increment it at the time we set
 497                 * it by one.
 498                 */
 499                crypto_inc(drbg->V, drbg_blocklen(drbg));
 500
 501                ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
 502                                             drbg_keylen(drbg));
 503                if (ret)
 504                        goto out;
 505        }
 506
 507        /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
 508        if (seed) {
 509                ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
 510                if (ret)
 511                        goto out;
 512        }
 513
 514        ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
 515                                 temp, drbg_statelen(drbg));
 516        if (ret)
 517                return ret;
 518
 519        /* 10.2.1.2 step 5 */
 520        ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
 521                                     drbg_keylen(drbg));
 522        if (ret)
 523                goto out;
 524        /* 10.2.1.2 step 6 */
 525        memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
 526        /* See above: increment counter by one to compensate timing of CTR op */
 527        crypto_inc(drbg->V, drbg_blocklen(drbg));
 528        ret = 0;
 529
 530out:
 531        memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
 532        if (2 != reseed)
 533                memset(df_data, 0, drbg_statelen(drbg));
 534        return ret;
 535}
 536
 537/*
 538 * scratchpad use: drbg_ctr_update is called independently from
 539 * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
 540 */
 541/* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
 542static int drbg_ctr_generate(struct drbg_state *drbg,
 543                             unsigned char *buf, unsigned int buflen,
 544                             struct list_head *addtl)
 545{
 546        int ret;
 547        int len = min_t(int, buflen, INT_MAX);
 548
 549        /* 10.2.1.5.2 step 2 */
 550        if (addtl && !list_empty(addtl)) {
 551                ret = drbg_ctr_update(drbg, addtl, 2);
 552                if (ret)
 553                        return 0;
 554        }
 555
 556        /* 10.2.1.5.2 step 4.1 */
 557        ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len);
 558        if (ret)
 559                return ret;
 560
 561        /* 10.2.1.5.2 step 6 */
 562        ret = drbg_ctr_update(drbg, NULL, 3);
 563        if (ret)
 564                len = ret;
 565
 566        return len;
 567}
 568
 569static const struct drbg_state_ops drbg_ctr_ops = {
 570        .update         = drbg_ctr_update,
 571        .generate       = drbg_ctr_generate,
 572        .crypto_init    = drbg_init_sym_kernel,
 573        .crypto_fini    = drbg_fini_sym_kernel,
 574};
 575#endif /* CONFIG_CRYPTO_DRBG_CTR */
 576
 577/******************************************************************
 578 * HMAC DRBG callback functions
 579 ******************************************************************/
 580
 581#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
 582static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
 583                           const struct list_head *in);
 584static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
 585                                  const unsigned char *key);
 586static int drbg_init_hash_kernel(struct drbg_state *drbg);
 587static int drbg_fini_hash_kernel(struct drbg_state *drbg);
 588#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
 589
 590#ifdef CONFIG_CRYPTO_DRBG_HMAC
 591#define CRYPTO_DRBG_HMAC_STRING "HMAC "
 592MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
 593MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
 594MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
 595MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
 596MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
 597MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
 598MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
 599MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
 600
 601/* update function of HMAC DRBG as defined in 10.1.2.2 */
 602static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
 603                            int reseed)
 604{
 605        int ret = -EFAULT;
 606        int i = 0;
 607        struct drbg_string seed1, seed2, vdata;
 608        LIST_HEAD(seedlist);
 609        LIST_HEAD(vdatalist);
 610
 611        if (!reseed) {
 612                /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
 613                memset(drbg->V, 1, drbg_statelen(drbg));
 614                drbg_kcapi_hmacsetkey(drbg, drbg->C);
 615        }
 616
 617        drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
 618        list_add_tail(&seed1.list, &seedlist);
 619        /* buffer of seed2 will be filled in for loop below with one byte */
 620        drbg_string_fill(&seed2, NULL, 1);
 621        list_add_tail(&seed2.list, &seedlist);
 622        /* input data of seed is allowed to be NULL at this point */
 623        if (seed)
 624                list_splice_tail(seed, &seedlist);
 625
 626        drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
 627        list_add_tail(&vdata.list, &vdatalist);
 628        for (i = 2; 0 < i; i--) {
 629                /* first round uses 0x0, second 0x1 */
 630                unsigned char prefix = DRBG_PREFIX0;
 631                if (1 == i)
 632                        prefix = DRBG_PREFIX1;
 633                /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
 634                seed2.buf = &prefix;
 635                ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
 636                if (ret)
 637                        return ret;
 638                drbg_kcapi_hmacsetkey(drbg, drbg->C);
 639
 640                /* 10.1.2.2 step 2 and 5 -- HMAC for V */
 641                ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
 642                if (ret)
 643                        return ret;
 644
 645                /* 10.1.2.2 step 3 */
 646                if (!seed)
 647                        return ret;
 648        }
 649
 650        return 0;
 651}
 652
 653/* generate function of HMAC DRBG as defined in 10.1.2.5 */
 654static int drbg_hmac_generate(struct drbg_state *drbg,
 655                              unsigned char *buf,
 656                              unsigned int buflen,
 657                              struct list_head *addtl)
 658{
 659        int len = 0;
 660        int ret = 0;
 661        struct drbg_string data;
 662        LIST_HEAD(datalist);
 663
 664        /* 10.1.2.5 step 2 */
 665        if (addtl && !list_empty(addtl)) {
 666                ret = drbg_hmac_update(drbg, addtl, 1);
 667                if (ret)
 668                        return ret;
 669        }
 670
 671        drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
 672        list_add_tail(&data.list, &datalist);
 673        while (len < buflen) {
 674                unsigned int outlen = 0;
 675                /* 10.1.2.5 step 4.1 */
 676                ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
 677                if (ret)
 678                        return ret;
 679                outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 680                          drbg_blocklen(drbg) : (buflen - len);
 681
 682                /* 10.1.2.5 step 4.2 */
 683                memcpy(buf + len, drbg->V, outlen);
 684                len += outlen;
 685        }
 686
 687        /* 10.1.2.5 step 6 */
 688        if (addtl && !list_empty(addtl))
 689                ret = drbg_hmac_update(drbg, addtl, 1);
 690        else
 691                ret = drbg_hmac_update(drbg, NULL, 1);
 692        if (ret)
 693                return ret;
 694
 695        return len;
 696}
 697
 698static const struct drbg_state_ops drbg_hmac_ops = {
 699        .update         = drbg_hmac_update,
 700        .generate       = drbg_hmac_generate,
 701        .crypto_init    = drbg_init_hash_kernel,
 702        .crypto_fini    = drbg_fini_hash_kernel,
 703};
 704#endif /* CONFIG_CRYPTO_DRBG_HMAC */
 705
 706/******************************************************************
 707 * Hash DRBG callback functions
 708 ******************************************************************/
 709
 710#ifdef CONFIG_CRYPTO_DRBG_HASH
 711#define CRYPTO_DRBG_HASH_STRING "HASH "
 712MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
 713MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
 714MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
 715MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
 716MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
 717MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
 718MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
 719MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
 720
 721/*
 722 * Increment buffer
 723 *
 724 * @dst buffer to increment
 725 * @add value to add
 726 */
 727static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
 728                                const unsigned char *add, size_t addlen)
 729{
 730        /* implied: dstlen > addlen */
 731        unsigned char *dstptr;
 732        const unsigned char *addptr;
 733        unsigned int remainder = 0;
 734        size_t len = addlen;
 735
 736        dstptr = dst + (dstlen-1);
 737        addptr = add + (addlen-1);
 738        while (len) {
 739                remainder += *dstptr + *addptr;
 740                *dstptr = remainder & 0xff;
 741                remainder >>= 8;
 742                len--; dstptr--; addptr--;
 743        }
 744        len = dstlen - addlen;
 745        while (len && remainder > 0) {
 746                remainder = *dstptr + 1;
 747                *dstptr = remainder & 0xff;
 748                remainder >>= 8;
 749                len--; dstptr--;
 750        }
 751}
 752
 753/*
 754 * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
 755 * interlinked, the scratchpad is used as follows:
 756 * drbg_hash_update
 757 *      start: drbg->scratchpad
 758 *      length: drbg_statelen(drbg)
 759 * drbg_hash_df:
 760 *      start: drbg->scratchpad + drbg_statelen(drbg)
 761 *      length: drbg_blocklen(drbg)
 762 *
 763 * drbg_hash_process_addtl uses the scratchpad, but fully completes
 764 * before either of the functions mentioned before are invoked. Therefore,
 765 * drbg_hash_process_addtl does not need to be specifically considered.
 766 */
 767
 768/* Derivation Function for Hash DRBG as defined in 10.4.1 */
 769static int drbg_hash_df(struct drbg_state *drbg,
 770                        unsigned char *outval, size_t outlen,
 771                        struct list_head *entropylist)
 772{
 773        int ret = 0;
 774        size_t len = 0;
 775        unsigned char input[5];
 776        unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
 777        struct drbg_string data;
 778
 779        /* 10.4.1 step 3 */
 780        input[0] = 1;
 781        drbg_cpu_to_be32((outlen * 8), &input[1]);
 782
 783        /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
 784        drbg_string_fill(&data, input, 5);
 785        list_add(&data.list, entropylist);
 786
 787        /* 10.4.1 step 4 */
 788        while (len < outlen) {
 789                short blocklen = 0;
 790                /* 10.4.1 step 4.1 */
 791                ret = drbg_kcapi_hash(drbg, tmp, entropylist);
 792                if (ret)
 793                        goto out;
 794                /* 10.4.1 step 4.2 */
 795                input[0]++;
 796                blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
 797                            drbg_blocklen(drbg) : (outlen - len);
 798                memcpy(outval + len, tmp, blocklen);
 799                len += blocklen;
 800        }
 801
 802out:
 803        memset(tmp, 0, drbg_blocklen(drbg));
 804        return ret;
 805}
 806
 807/* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
 808static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
 809                            int reseed)
 810{
 811        int ret = 0;
 812        struct drbg_string data1, data2;
 813        LIST_HEAD(datalist);
 814        LIST_HEAD(datalist2);
 815        unsigned char *V = drbg->scratchpad;
 816        unsigned char prefix = DRBG_PREFIX1;
 817
 818        if (!seed)
 819                return -EINVAL;
 820
 821        if (reseed) {
 822                /* 10.1.1.3 step 1 */
 823                memcpy(V, drbg->V, drbg_statelen(drbg));
 824                drbg_string_fill(&data1, &prefix, 1);
 825                list_add_tail(&data1.list, &datalist);
 826                drbg_string_fill(&data2, V, drbg_statelen(drbg));
 827                list_add_tail(&data2.list, &datalist);
 828        }
 829        list_splice_tail(seed, &datalist);
 830
 831        /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
 832        ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
 833        if (ret)
 834                goto out;
 835
 836        /* 10.1.1.2 / 10.1.1.3 step 4  */
 837        prefix = DRBG_PREFIX0;
 838        drbg_string_fill(&data1, &prefix, 1);
 839        list_add_tail(&data1.list, &datalist2);
 840        drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 841        list_add_tail(&data2.list, &datalist2);
 842        /* 10.1.1.2 / 10.1.1.3 step 4 */
 843        ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
 844
 845out:
 846        memset(drbg->scratchpad, 0, drbg_statelen(drbg));
 847        return ret;
 848}
 849
 850/* processing of additional information string for Hash DRBG */
 851static int drbg_hash_process_addtl(struct drbg_state *drbg,
 852                                   struct list_head *addtl)
 853{
 854        int ret = 0;
 855        struct drbg_string data1, data2;
 856        LIST_HEAD(datalist);
 857        unsigned char prefix = DRBG_PREFIX2;
 858
 859        /* 10.1.1.4 step 2 */
 860        if (!addtl || list_empty(addtl))
 861                return 0;
 862
 863        /* 10.1.1.4 step 2a */
 864        drbg_string_fill(&data1, &prefix, 1);
 865        drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 866        list_add_tail(&data1.list, &datalist);
 867        list_add_tail(&data2.list, &datalist);
 868        list_splice_tail(addtl, &datalist);
 869        ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
 870        if (ret)
 871                goto out;
 872
 873        /* 10.1.1.4 step 2b */
 874        drbg_add_buf(drbg->V, drbg_statelen(drbg),
 875                     drbg->scratchpad, drbg_blocklen(drbg));
 876
 877out:
 878        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 879        return ret;
 880}
 881
 882/* Hashgen defined in 10.1.1.4 */
 883static int drbg_hash_hashgen(struct drbg_state *drbg,
 884                             unsigned char *buf,
 885                             unsigned int buflen)
 886{
 887        int len = 0;
 888        int ret = 0;
 889        unsigned char *src = drbg->scratchpad;
 890        unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
 891        struct drbg_string data;
 892        LIST_HEAD(datalist);
 893
 894        /* 10.1.1.4 step hashgen 2 */
 895        memcpy(src, drbg->V, drbg_statelen(drbg));
 896
 897        drbg_string_fill(&data, src, drbg_statelen(drbg));
 898        list_add_tail(&data.list, &datalist);
 899        while (len < buflen) {
 900                unsigned int outlen = 0;
 901                /* 10.1.1.4 step hashgen 4.1 */
 902                ret = drbg_kcapi_hash(drbg, dst, &datalist);
 903                if (ret) {
 904                        len = ret;
 905                        goto out;
 906                }
 907                outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
 908                          drbg_blocklen(drbg) : (buflen - len);
 909                /* 10.1.1.4 step hashgen 4.2 */
 910                memcpy(buf + len, dst, outlen);
 911                len += outlen;
 912                /* 10.1.1.4 hashgen step 4.3 */
 913                if (len < buflen)
 914                        crypto_inc(src, drbg_statelen(drbg));
 915        }
 916
 917out:
 918        memset(drbg->scratchpad, 0,
 919               (drbg_statelen(drbg) + drbg_blocklen(drbg)));
 920        return len;
 921}
 922
 923/* generate function for Hash DRBG as defined in  10.1.1.4 */
 924static int drbg_hash_generate(struct drbg_state *drbg,
 925                              unsigned char *buf, unsigned int buflen,
 926                              struct list_head *addtl)
 927{
 928        int len = 0;
 929        int ret = 0;
 930        union {
 931                unsigned char req[8];
 932                __be64 req_int;
 933        } u;
 934        unsigned char prefix = DRBG_PREFIX3;
 935        struct drbg_string data1, data2;
 936        LIST_HEAD(datalist);
 937
 938        /* 10.1.1.4 step 2 */
 939        ret = drbg_hash_process_addtl(drbg, addtl);
 940        if (ret)
 941                return ret;
 942        /* 10.1.1.4 step 3 */
 943        len = drbg_hash_hashgen(drbg, buf, buflen);
 944
 945        /* this is the value H as documented in 10.1.1.4 */
 946        /* 10.1.1.4 step 4 */
 947        drbg_string_fill(&data1, &prefix, 1);
 948        list_add_tail(&data1.list, &datalist);
 949        drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
 950        list_add_tail(&data2.list, &datalist);
 951        ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
 952        if (ret) {
 953                len = ret;
 954                goto out;
 955        }
 956
 957        /* 10.1.1.4 step 5 */
 958        drbg_add_buf(drbg->V, drbg_statelen(drbg),
 959                     drbg->scratchpad, drbg_blocklen(drbg));
 960        drbg_add_buf(drbg->V, drbg_statelen(drbg),
 961                     drbg->C, drbg_statelen(drbg));
 962        u.req_int = cpu_to_be64(drbg->reseed_ctr);
 963        drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
 964
 965out:
 966        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 967        return len;
 968}
 969
 970/*
 971 * scratchpad usage: as update and generate are used isolated, both
 972 * can use the scratchpad
 973 */
 974static const struct drbg_state_ops drbg_hash_ops = {
 975        .update         = drbg_hash_update,
 976        .generate       = drbg_hash_generate,
 977        .crypto_init    = drbg_init_hash_kernel,
 978        .crypto_fini    = drbg_fini_hash_kernel,
 979};
 980#endif /* CONFIG_CRYPTO_DRBG_HASH */
 981
 982/******************************************************************
 983 * Functions common for DRBG implementations
 984 ******************************************************************/
 985
 986static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
 987                              int reseed)
 988{
 989        int ret = drbg->d_ops->update(drbg, seed, reseed);
 990
 991        if (ret)
 992                return ret;
 993
 994        drbg->seeded = true;
 995        /* 10.1.1.2 / 10.1.1.3 step 5 */
 996        drbg->reseed_ctr = 1;
 997
 998        return ret;
 999}
1000
1001static void drbg_async_seed(struct work_struct *work)
1002{
1003        struct drbg_string data;
1004        LIST_HEAD(seedlist);
1005        struct drbg_state *drbg = container_of(work, struct drbg_state,
1006                                               seed_work);
1007        unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1008        unsigned char entropy[32];
1009
1010        BUG_ON(!entropylen);
1011        BUG_ON(entropylen > sizeof(entropy));
1012        get_random_bytes(entropy, entropylen);
1013
1014        drbg_string_fill(&data, entropy, entropylen);
1015        list_add_tail(&data.list, &seedlist);
1016
1017        mutex_lock(&drbg->drbg_mutex);
1018
1019        /* If nonblocking pool is initialized, deactivate Jitter RNG */
1020        crypto_free_rng(drbg->jent);
1021        drbg->jent = NULL;
1022
1023        /* Set seeded to false so that if __drbg_seed fails the
1024         * next generate call will trigger a reseed.
1025         */
1026        drbg->seeded = false;
1027
1028        __drbg_seed(drbg, &seedlist, true);
1029
1030        if (drbg->seeded)
1031                drbg->reseed_threshold = drbg_max_requests(drbg);
1032
1033        mutex_unlock(&drbg->drbg_mutex);
1034
1035        memzero_explicit(entropy, entropylen);
1036}
1037
1038/*
1039 * Seeding or reseeding of the DRBG
1040 *
1041 * @drbg: DRBG state struct
1042 * @pers: personalization / additional information buffer
1043 * @reseed: 0 for initial seed process, 1 for reseeding
1044 *
1045 * return:
1046 *      0 on success
1047 *      error value otherwise
1048 */
1049static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1050                     bool reseed)
1051{
1052        int ret;
1053        unsigned char entropy[((32 + 16) * 2)];
1054        unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1055        struct drbg_string data1;
1056        LIST_HEAD(seedlist);
1057
1058        /* 9.1 / 9.2 / 9.3.1 step 3 */
1059        if (pers && pers->len > (drbg_max_addtl(drbg))) {
1060                pr_devel("DRBG: personalization string too long %zu\n",
1061                         pers->len);
1062                return -EINVAL;
1063        }
1064
1065        if (list_empty(&drbg->test_data.list)) {
1066                drbg_string_fill(&data1, drbg->test_data.buf,
1067                                 drbg->test_data.len);
1068                pr_devel("DRBG: using test entropy\n");
1069        } else {
1070                /*
1071                 * Gather entropy equal to the security strength of the DRBG.
1072                 * With a derivation function, a nonce is required in addition
1073                 * to the entropy. A nonce must be at least 1/2 of the security
1074                 * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1075                 * of the strength. The consideration of a nonce is only
1076                 * applicable during initial seeding.
1077                 */
1078                BUG_ON(!entropylen);
1079                if (!reseed)
1080                        entropylen = ((entropylen + 1) / 2) * 3;
1081                BUG_ON((entropylen * 2) > sizeof(entropy));
1082
1083                /* Get seed from in-kernel /dev/urandom */
1084                get_random_bytes(entropy, entropylen);
1085
1086                if (!drbg->jent) {
1087                        drbg_string_fill(&data1, entropy, entropylen);
1088                        pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1089                                 entropylen);
1090                } else {
1091                        /* Get seed from Jitter RNG */
1092                        ret = crypto_rng_get_bytes(drbg->jent,
1093                                                   entropy + entropylen,
1094                                                   entropylen);
1095                        if (ret) {
1096                                pr_devel("DRBG: jent failed with %d\n", ret);
1097                                return ret;
1098                        }
1099
1100                        drbg_string_fill(&data1, entropy, entropylen * 2);
1101                        pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1102                                 entropylen * 2);
1103                }
1104        }
1105        list_add_tail(&data1.list, &seedlist);
1106
1107        /*
1108         * concatenation of entropy with personalization str / addtl input)
1109         * the variable pers is directly handed in by the caller, so check its
1110         * contents whether it is appropriate
1111         */
1112        if (pers && pers->buf && 0 < pers->len) {
1113                list_add_tail(&pers->list, &seedlist);
1114                pr_devel("DRBG: using personalization string\n");
1115        }
1116
1117        if (!reseed) {
1118                memset(drbg->V, 0, drbg_statelen(drbg));
1119                memset(drbg->C, 0, drbg_statelen(drbg));
1120        }
1121
1122        ret = __drbg_seed(drbg, &seedlist, reseed);
1123
1124        memzero_explicit(entropy, entropylen * 2);
1125
1126        return ret;
1127}
1128
1129/* Free all substructures in a DRBG state without the DRBG state structure */
1130static inline void drbg_dealloc_state(struct drbg_state *drbg)
1131{
1132        if (!drbg)
1133                return;
1134        kzfree(drbg->Vbuf);
1135        drbg->Vbuf = NULL;
1136        drbg->V = NULL;
1137        kzfree(drbg->Cbuf);
1138        drbg->Cbuf = NULL;
1139        drbg->C = 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->outscratchpadbuf);
1646        drbg->outscratchpadbuf = NULL;
1647
1648        return 0;
1649}
1650
1651static int drbg_init_sym_kernel(struct drbg_state *drbg)
1652{
1653        struct crypto_cipher *tfm;
1654        struct crypto_skcipher *sk_tfm;
1655        struct skcipher_request *req;
1656        unsigned int alignmask;
1657        char ctr_name[CRYPTO_MAX_ALG_NAME];
1658
1659        tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1660        if (IS_ERR(tfm)) {
1661                pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1662                                drbg->core->backend_cra_name);
1663                return PTR_ERR(tfm);
1664        }
1665        BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1666        drbg->priv_data = tfm;
1667
1668        if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1669            drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1670                drbg_fini_sym_kernel(drbg);
1671                return -EINVAL;
1672        }
1673        sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1674        if (IS_ERR(sk_tfm)) {
1675                pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1676                                ctr_name);
1677                drbg_fini_sym_kernel(drbg);
1678                return PTR_ERR(sk_tfm);
1679        }
1680        drbg->ctr_handle = sk_tfm;
1681        crypto_init_wait(&drbg->ctr_wait);
1682
1683        req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1684        if (!req) {
1685                pr_info("DRBG: could not allocate request queue\n");
1686                drbg_fini_sym_kernel(drbg);
1687                return -ENOMEM;
1688        }
1689        drbg->ctr_req = req;
1690        skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
1691                                                CRYPTO_TFM_REQ_MAY_SLEEP,
1692                                        crypto_req_done, &drbg->ctr_wait);
1693
1694        alignmask = crypto_skcipher_alignmask(sk_tfm);
1695        drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
1696                                         GFP_KERNEL);
1697        if (!drbg->outscratchpadbuf) {
1698                drbg_fini_sym_kernel(drbg);
1699                return -ENOMEM;
1700        }
1701        drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
1702                                              alignmask + 1);
1703
1704        sg_init_table(&drbg->sg_in, 1);
1705        sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1706
1707        return alignmask;
1708}
1709
1710static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1711                                 const unsigned char *key)
1712{
1713        struct crypto_cipher *tfm =
1714                (struct crypto_cipher *)drbg->priv_data;
1715
1716        crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1717}
1718
1719static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1720                          const struct drbg_string *in)
1721{
1722        struct crypto_cipher *tfm =
1723                (struct crypto_cipher *)drbg->priv_data;
1724
1725        /* there is only component in *in */
1726        BUG_ON(in->len < drbg_blocklen(drbg));
1727        crypto_cipher_encrypt_one(tfm, outval, in->buf);
1728        return 0;
1729}
1730
1731static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1732                              u8 *inbuf, u32 inlen,
1733                              u8 *outbuf, u32 outlen)
1734{
1735        struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;
1736        u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN);
1737        int ret;
1738
1739        if (inbuf) {
1740                /* Use caller-provided input buffer */
1741                sg_set_buf(sg_in, inbuf, inlen);
1742        } else {
1743                /* Use scratchpad for in-place operation */
1744                inlen = scratchpad_use;
1745                memset(drbg->outscratchpad, 0, scratchpad_use);
1746                sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use);
1747        }
1748
1749        while (outlen) {
1750                u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1751
1752                /* Output buffer may not be valid for SGL, use scratchpad */
1753                skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out,
1754                                           cryptlen, drbg->V);
1755                ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
1756                                        &drbg->ctr_wait);
1757                if (ret)
1758                        goto out;
1759
1760                crypto_init_wait(&drbg->ctr_wait);
1761
1762                memcpy(outbuf, drbg->outscratchpad, cryptlen);
1763                memzero_explicit(drbg->outscratchpad, cryptlen);
1764
1765                outlen -= cryptlen;
1766                outbuf += cryptlen;
1767        }
1768        ret = 0;
1769
1770out:
1771        return ret;
1772}
1773#endif /* CONFIG_CRYPTO_DRBG_CTR */
1774
1775/***************************************************************
1776 * Kernel crypto API interface to register DRBG
1777 ***************************************************************/
1778
1779/*
1780 * Look up the DRBG flags by given kernel crypto API cra_name
1781 * The code uses the drbg_cores definition to do this
1782 *
1783 * @cra_name kernel crypto API cra_name
1784 * @coreref reference to integer which is filled with the pointer to
1785 *  the applicable core
1786 * @pr reference for setting prediction resistance
1787 *
1788 * return: flags
1789 */
1790static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1791                                         int *coreref, bool *pr)
1792{
1793        int i = 0;
1794        size_t start = 0;
1795        int len = 0;
1796
1797        *pr = true;
1798        /* disassemble the names */
1799        if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1800                start = 10;
1801                *pr = false;
1802        } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1803                start = 8;
1804        } else {
1805                return;
1806        }
1807
1808        /* remove the first part */
1809        len = strlen(cra_driver_name) - start;
1810        for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1811                if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1812                            len)) {
1813                        *coreref = i;
1814                        return;
1815                }
1816        }
1817}
1818
1819static int drbg_kcapi_init(struct crypto_tfm *tfm)
1820{
1821        struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1822
1823        mutex_init(&drbg->drbg_mutex);
1824
1825        return 0;
1826}
1827
1828static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1829{
1830        drbg_uninstantiate(crypto_tfm_ctx(tfm));
1831}
1832
1833/*
1834 * Generate random numbers invoked by the kernel crypto API:
1835 * The API of the kernel crypto API is extended as follows:
1836 *
1837 * src is additional input supplied to the RNG.
1838 * slen is the length of src.
1839 * dst is the output buffer where random data is to be stored.
1840 * dlen is the length of dst.
1841 */
1842static int drbg_kcapi_random(struct crypto_rng *tfm,
1843                             const u8 *src, unsigned int slen,
1844                             u8 *dst, unsigned int dlen)
1845{
1846        struct drbg_state *drbg = crypto_rng_ctx(tfm);
1847        struct drbg_string *addtl = NULL;
1848        struct drbg_string string;
1849
1850        if (slen) {
1851                /* linked list variable is now local to allow modification */
1852                drbg_string_fill(&string, src, slen);
1853                addtl = &string;
1854        }
1855
1856        return drbg_generate_long(drbg, dst, dlen, addtl);
1857}
1858
1859/*
1860 * Seed the DRBG invoked by the kernel crypto API
1861 */
1862static int drbg_kcapi_seed(struct crypto_rng *tfm,
1863                           const u8 *seed, unsigned int slen)
1864{
1865        struct drbg_state *drbg = crypto_rng_ctx(tfm);
1866        struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1867        bool pr = false;
1868        struct drbg_string string;
1869        struct drbg_string *seed_string = NULL;
1870        int coreref = 0;
1871
1872        drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1873                              &pr);
1874        if (0 < slen) {
1875                drbg_string_fill(&string, seed, slen);
1876                seed_string = &string;
1877        }
1878
1879        return drbg_instantiate(drbg, seed_string, coreref, pr);
1880}
1881
1882/***************************************************************
1883 * Kernel module: code to load the module
1884 ***************************************************************/
1885
1886/*
1887 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1888 * of the error handling.
1889 *
1890 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1891 * as seed source of get_random_bytes does not fail.
1892 *
1893 * Note 2: There is no sensible way of testing the reseed counter
1894 * enforcement, so skip it.
1895 */
1896static inline int __init drbg_healthcheck_sanity(void)
1897{
1898        int len = 0;
1899#define OUTBUFLEN 16
1900        unsigned char buf[OUTBUFLEN];
1901        struct drbg_state *drbg = NULL;
1902        int ret = -EFAULT;
1903        int rc = -EFAULT;
1904        bool pr = false;
1905        int coreref = 0;
1906        struct drbg_string addtl;
1907        size_t max_addtllen, max_request_bytes;
1908
1909        /* only perform test in FIPS mode */
1910        if (!fips_enabled)
1911                return 0;
1912
1913#ifdef CONFIG_CRYPTO_DRBG_CTR
1914        drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1915#elif defined CONFIG_CRYPTO_DRBG_HASH
1916        drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1917#else
1918        drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1919#endif
1920
1921        drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1922        if (!drbg)
1923                return -ENOMEM;
1924
1925        mutex_init(&drbg->drbg_mutex);
1926        drbg->core = &drbg_cores[coreref];
1927        drbg->reseed_threshold = drbg_max_requests(drbg);
1928
1929        /*
1930         * if the following tests fail, it is likely that there is a buffer
1931         * overflow as buf is much smaller than the requested or provided
1932         * string lengths -- in case the error handling does not succeed
1933         * we may get an OOPS. And we want to get an OOPS as this is a
1934         * grave bug.
1935         */
1936
1937        max_addtllen = drbg_max_addtl(drbg);
1938        max_request_bytes = drbg_max_request_bytes(drbg);
1939        drbg_string_fill(&addtl, buf, max_addtllen + 1);
1940        /* overflow addtllen with additonal info string */
1941        len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1942        BUG_ON(0 < len);
1943        /* overflow max_bits */
1944        len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1945        BUG_ON(0 < len);
1946
1947        /* overflow max addtllen with personalization string */
1948        ret = drbg_seed(drbg, &addtl, false);
1949        BUG_ON(0 == ret);
1950        /* all tests passed */
1951        rc = 0;
1952
1953        pr_devel("DRBG: Sanity tests for failure code paths successfully "
1954                 "completed\n");
1955
1956        kfree(drbg);
1957        return rc;
1958}
1959
1960static struct rng_alg drbg_algs[22];
1961
1962/*
1963 * Fill the array drbg_algs used to register the different DRBGs
1964 * with the kernel crypto API. To fill the array, the information
1965 * from drbg_cores[] is used.
1966 */
1967static inline void __init drbg_fill_array(struct rng_alg *alg,
1968                                          const struct drbg_core *core, int pr)
1969{
1970        int pos = 0;
1971        static int priority = 200;
1972
1973        memcpy(alg->base.cra_name, "stdrng", 6);
1974        if (pr) {
1975                memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
1976                pos = 8;
1977        } else {
1978                memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
1979                pos = 10;
1980        }
1981        memcpy(alg->base.cra_driver_name + pos, core->cra_name,
1982               strlen(core->cra_name));
1983
1984        alg->base.cra_priority = priority;
1985        priority++;
1986        /*
1987         * If FIPS mode enabled, the selected DRBG shall have the
1988         * highest cra_priority over other stdrng instances to ensure
1989         * it is selected.
1990         */
1991        if (fips_enabled)
1992                alg->base.cra_priority += 200;
1993
1994        alg->base.cra_ctxsize   = sizeof(struct drbg_state);
1995        alg->base.cra_module    = THIS_MODULE;
1996        alg->base.cra_init      = drbg_kcapi_init;
1997        alg->base.cra_exit      = drbg_kcapi_cleanup;
1998        alg->generate           = drbg_kcapi_random;
1999        alg->seed               = drbg_kcapi_seed;
2000        alg->set_ent            = drbg_kcapi_set_entropy;
2001        alg->seedsize           = 0;
2002}
2003
2004static int __init drbg_init(void)
2005{
2006        unsigned int i = 0; /* pointer to drbg_algs */
2007        unsigned int j = 0; /* pointer to drbg_cores */
2008        int ret;
2009
2010        ret = drbg_healthcheck_sanity();
2011        if (ret)
2012                return ret;
2013
2014        if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2015                pr_info("DRBG: Cannot register all DRBG types"
2016                        "(slots needed: %zu, slots available: %zu)\n",
2017                        ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2018                return -EFAULT;
2019        }
2020
2021        /*
2022         * each DRBG definition can be used with PR and without PR, thus
2023         * we instantiate each DRBG in drbg_cores[] twice.
2024         *
2025         * As the order of placing them into the drbg_algs array matters
2026         * (the later DRBGs receive a higher cra_priority) we register the
2027         * prediction resistance DRBGs first as the should not be too
2028         * interesting.
2029         */
2030        for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2031                drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2032        for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2033                drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2034        return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2035}
2036
2037static void __exit drbg_exit(void)
2038{
2039        crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2040}
2041
2042module_init(drbg_init);
2043module_exit(drbg_exit);
2044#ifndef CRYPTO_DRBG_HASH_STRING
2045#define CRYPTO_DRBG_HASH_STRING ""
2046#endif
2047#ifndef CRYPTO_DRBG_HMAC_STRING
2048#define CRYPTO_DRBG_HMAC_STRING ""
2049#endif
2050#ifndef CRYPTO_DRBG_CTR_STRING
2051#define CRYPTO_DRBG_CTR_STRING ""
2052#endif
2053MODULE_LICENSE("GPL");
2054MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2055MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2056                   "using following cores: "
2057                   CRYPTO_DRBG_HASH_STRING
2058                   CRYPTO_DRBG_HMAC_STRING
2059                   CRYPTO_DRBG_CTR_STRING);
2060MODULE_ALIAS_CRYPTO("stdrng");
2061