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->Vbuf);
1137	drbg->Vbuf = NULL;
1138	drbg->V = NULL;
1139	kzfree(drbg->Cbuf);
1140	drbg->Cbuf = NULL;
1141	drbg->C = NULL;
1142	kzfree(drbg->scratchpadbuf);
1143	drbg->scratchpadbuf = NULL;
1144	drbg->reseed_ctr = 0;
1145	drbg->d_ops = NULL;
1146	drbg->core = NULL;
 
 
 
 
 
1147}
1148
1149/*
1150 * Allocate all sub-structures for a DRBG state.
1151 * The DRBG state structure must already be allocated.
1152 */
1153static inline int drbg_alloc_state(struct drbg_state *drbg)
1154{
1155	int ret = -ENOMEM;
1156	unsigned int sb_size = 0;
1157
1158	switch (drbg->core->flags & DRBG_TYPE_MASK) {
1159#ifdef CONFIG_CRYPTO_DRBG_HMAC
1160	case DRBG_HMAC:
1161		drbg->d_ops = &drbg_hmac_ops;
1162		break;
1163#endif /* CONFIG_CRYPTO_DRBG_HMAC */
1164#ifdef CONFIG_CRYPTO_DRBG_HASH
1165	case DRBG_HASH:
1166		drbg->d_ops = &drbg_hash_ops;
1167		break;
1168#endif /* CONFIG_CRYPTO_DRBG_HASH */
1169#ifdef CONFIG_CRYPTO_DRBG_CTR
1170	case DRBG_CTR:
1171		drbg->d_ops = &drbg_ctr_ops;
1172		break;
1173#endif /* CONFIG_CRYPTO_DRBG_CTR */
1174	default:
1175		ret = -EOPNOTSUPP;
1176		goto err;
1177	}
1178
1179	ret = drbg->d_ops->crypto_init(drbg);
1180	if (ret < 0)
1181		goto err;
1182
1183	drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1184	if (!drbg->Vbuf) {
1185		ret = -ENOMEM;
1186		goto fini;
1187	}
1188	drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
1189	drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1190	if (!drbg->Cbuf) {
1191		ret = -ENOMEM;
1192		goto fini;
1193	}
1194	drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);
1195	/* scratchpad is only generated for CTR and Hash */
1196	if (drbg->core->flags & DRBG_HMAC)
1197		sb_size = 0;
1198	else if (drbg->core->flags & DRBG_CTR)
1199		sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1200			  drbg_statelen(drbg) +	/* df_data */
1201			  drbg_blocklen(drbg) +	/* pad */
1202			  drbg_blocklen(drbg) +	/* iv */
1203			  drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1204	else
1205		sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1206
1207	if (0 < sb_size) {
1208		drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);
1209		if (!drbg->scratchpadbuf) {
1210			ret = -ENOMEM;
1211			goto fini;
1212		}
1213		drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);
1214	}
1215
 
 
 
 
 
 
 
 
 
 
1216	return 0;
1217
1218fini:
1219	drbg->d_ops->crypto_fini(drbg);
1220err:
1221	drbg_dealloc_state(drbg);
1222	return ret;
1223}
1224
1225/*************************************************************************
1226 * DRBG interface functions
1227 *************************************************************************/
1228
1229/*
1230 * DRBG generate function as required by SP800-90A - this function
1231 * generates random numbers
1232 *
1233 * @drbg DRBG state handle
1234 * @buf Buffer where to store the random numbers -- the buffer must already
1235 *      be pre-allocated by caller
1236 * @buflen Length of output buffer - this value defines the number of random
1237 *	   bytes pulled from DRBG
1238 * @addtl Additional input that is mixed into state, may be NULL -- note
1239 *	  the entropy is pulled by the DRBG internally unconditionally
1240 *	  as defined in SP800-90A. The additional input is mixed into
1241 *	  the state in addition to the pulled entropy.
1242 *
1243 * return: 0 when all bytes are generated; < 0 in case of an error
1244 */
1245static int drbg_generate(struct drbg_state *drbg,
1246			 unsigned char *buf, unsigned int buflen,
1247			 struct drbg_string *addtl)
1248{
1249	int len = 0;
1250	LIST_HEAD(addtllist);
1251
1252	if (!drbg->core) {
1253		pr_devel("DRBG: not yet seeded\n");
1254		return -EINVAL;
1255	}
1256	if (0 == buflen || !buf) {
1257		pr_devel("DRBG: no output buffer provided\n");
1258		return -EINVAL;
1259	}
1260	if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1261		pr_devel("DRBG: wrong format of additional information\n");
1262		return -EINVAL;
1263	}
1264
1265	/* 9.3.1 step 2 */
1266	len = -EINVAL;
1267	if (buflen > (drbg_max_request_bytes(drbg))) {
1268		pr_devel("DRBG: requested random numbers too large %u\n",
1269			 buflen);
1270		goto err;
1271	}
1272
1273	/* 9.3.1 step 3 is implicit with the chosen DRBG */
1274
1275	/* 9.3.1 step 4 */
1276	if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1277		pr_devel("DRBG: additional information string too long %zu\n",
1278			 addtl->len);
1279		goto err;
1280	}
1281	/* 9.3.1 step 5 is implicit with the chosen DRBG */
1282
1283	/*
1284	 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1285	 * here. The spec is a bit convoluted here, we make it simpler.
1286	 */
1287	if (drbg->reseed_threshold < drbg->reseed_ctr)
1288		drbg->seeded = false;
1289
1290	if (drbg->pr || !drbg->seeded) {
1291		pr_devel("DRBG: reseeding before generation (prediction "
1292			 "resistance: %s, state %s)\n",
1293			 drbg->pr ? "true" : "false",
1294			 drbg->seeded ? "seeded" : "unseeded");
1295		/* 9.3.1 steps 7.1 through 7.3 */
1296		len = drbg_seed(drbg, addtl, true);
1297		if (len)
1298			goto err;
1299		/* 9.3.1 step 7.4 */
1300		addtl = NULL;
1301	}
1302
1303	if (addtl && 0 < addtl->len)
1304		list_add_tail(&addtl->list, &addtllist);
1305	/* 9.3.1 step 8 and 10 */
1306	len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1307
1308	/* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1309	drbg->reseed_ctr++;
1310	if (0 >= len)
1311		goto err;
1312
1313	/*
1314	 * Section 11.3.3 requires to re-perform self tests after some
1315	 * generated random numbers. The chosen value after which self
1316	 * test is performed is arbitrary, but it should be reasonable.
1317	 * However, we do not perform the self tests because of the following
1318	 * reasons: it is mathematically impossible that the initial self tests
1319	 * were successfully and the following are not. If the initial would
1320	 * pass and the following would not, the kernel integrity is violated.
1321	 * In this case, the entire kernel operation is questionable and it
1322	 * is unlikely that the integrity violation only affects the
1323	 * correct operation of the DRBG.
1324	 *
1325	 * Albeit the following code is commented out, it is provided in
1326	 * case somebody has a need to implement the test of 11.3.3.
1327	 */
1328#if 0
1329	if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1330		int err = 0;
1331		pr_devel("DRBG: start to perform self test\n");
1332		if (drbg->core->flags & DRBG_HMAC)
1333			err = alg_test("drbg_pr_hmac_sha256",
1334				       "drbg_pr_hmac_sha256", 0, 0);
1335		else if (drbg->core->flags & DRBG_CTR)
1336			err = alg_test("drbg_pr_ctr_aes128",
1337				       "drbg_pr_ctr_aes128", 0, 0);
1338		else
1339			err = alg_test("drbg_pr_sha256",
1340				       "drbg_pr_sha256", 0, 0);
1341		if (err) {
1342			pr_err("DRBG: periodical self test failed\n");
1343			/*
1344			 * uninstantiate implies that from now on, only errors
1345			 * are returned when reusing this DRBG cipher handle
1346			 */
1347			drbg_uninstantiate(drbg);
1348			return 0;
1349		} else {
1350			pr_devel("DRBG: self test successful\n");
1351		}
1352	}
1353#endif
1354
1355	/*
1356	 * All operations were successful, return 0 as mandated by
1357	 * the kernel crypto API interface.
1358	 */
1359	len = 0;
1360err:
1361	return len;
1362}
1363
1364/*
1365 * Wrapper around drbg_generate which can pull arbitrary long strings
1366 * from the DRBG without hitting the maximum request limitation.
1367 *
1368 * Parameters: see drbg_generate
1369 * Return codes: see drbg_generate -- if one drbg_generate request fails,
1370 *		 the entire drbg_generate_long request fails
1371 */
1372static int drbg_generate_long(struct drbg_state *drbg,
1373			      unsigned char *buf, unsigned int buflen,
1374			      struct drbg_string *addtl)
1375{
1376	unsigned int len = 0;
1377	unsigned int slice = 0;
1378	do {
1379		int err = 0;
1380		unsigned int chunk = 0;
1381		slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1382		chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1383		mutex_lock(&drbg->drbg_mutex);
1384		err = drbg_generate(drbg, buf + len, chunk, addtl);
1385		mutex_unlock(&drbg->drbg_mutex);
1386		if (0 > err)
1387			return err;
1388		len += chunk;
1389	} while (slice > 0 && (len < buflen));
1390	return 0;
1391}
1392
1393static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
1394{
1395	struct drbg_state *drbg = container_of(rdy, struct drbg_state,
1396					       random_ready);
1397
1398	schedule_work(&drbg->seed_work);
1399}
1400
1401static int drbg_prepare_hrng(struct drbg_state *drbg)
1402{
1403	int err;
1404
1405	/* We do not need an HRNG in test mode. */
1406	if (list_empty(&drbg->test_data.list))
1407		return 0;
1408
 
 
1409	INIT_WORK(&drbg->seed_work, drbg_async_seed);
1410
1411	drbg->random_ready.owner = THIS_MODULE;
1412	drbg->random_ready.func = drbg_schedule_async_seed;
1413
1414	err = add_random_ready_callback(&drbg->random_ready);
1415
1416	switch (err) {
1417	case 0:
1418		break;
1419
1420	case -EALREADY:
1421		err = 0;
1422		/* fall through */
1423
1424	default:
1425		drbg->random_ready.func = NULL;
1426		return err;
1427	}
1428
1429	drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
1430
1431	/*
1432	 * Require frequent reseeds until the seed source is fully
1433	 * initialized.
1434	 */
1435	drbg->reseed_threshold = 50;
1436
1437	return err;
1438}
1439
1440/*
1441 * DRBG instantiation function as required by SP800-90A - this function
1442 * sets up the DRBG handle, performs the initial seeding and all sanity
1443 * checks required by SP800-90A
1444 *
1445 * @drbg memory of state -- if NULL, new memory is allocated
1446 * @pers Personalization string that is mixed into state, may be NULL -- note
1447 *	 the entropy is pulled by the DRBG internally unconditionally
1448 *	 as defined in SP800-90A. The additional input is mixed into
1449 *	 the state in addition to the pulled entropy.
1450 * @coreref reference to core
1451 * @pr prediction resistance enabled
1452 *
1453 * return
1454 *	0 on success
1455 *	error value otherwise
1456 */
1457static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1458			    int coreref, bool pr)
1459{
1460	int ret;
1461	bool reseed = true;
1462
1463	pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1464		 "%s\n", coreref, pr ? "enabled" : "disabled");
1465	mutex_lock(&drbg->drbg_mutex);
1466
1467	/* 9.1 step 1 is implicit with the selected DRBG type */
1468
1469	/*
1470	 * 9.1 step 2 is implicit as caller can select prediction resistance
1471	 * and the flag is copied into drbg->flags --
1472	 * all DRBG types support prediction resistance
1473	 */
1474
1475	/* 9.1 step 4 is implicit in  drbg_sec_strength */
1476
1477	if (!drbg->core) {
1478		drbg->core = &drbg_cores[coreref];
1479		drbg->pr = pr;
1480		drbg->seeded = false;
1481		drbg->reseed_threshold = drbg_max_requests(drbg);
1482
1483		ret = drbg_alloc_state(drbg);
1484		if (ret)
1485			goto unlock;
1486
1487		ret = drbg_prepare_hrng(drbg);
1488		if (ret)
1489			goto free_everything;
1490
1491		if (IS_ERR(drbg->jent)) {
1492			ret = PTR_ERR(drbg->jent);
1493			drbg->jent = NULL;
1494			if (fips_enabled || ret != -ENOENT)
1495				goto free_everything;
1496			pr_info("DRBG: Continuing without Jitter RNG\n");
1497		}
1498
1499		reseed = false;
1500	}
1501
1502	ret = drbg_seed(drbg, pers, reseed);
1503
1504	if (ret && !reseed)
1505		goto free_everything;
1506
1507	mutex_unlock(&drbg->drbg_mutex);
1508	return ret;
1509
1510unlock:
1511	mutex_unlock(&drbg->drbg_mutex);
1512	return ret;
1513
1514free_everything:
1515	mutex_unlock(&drbg->drbg_mutex);
1516	drbg_uninstantiate(drbg);
1517	return ret;
1518}
1519
1520/*
1521 * DRBG uninstantiate function as required by SP800-90A - this function
1522 * frees all buffers and the DRBG handle
1523 *
1524 * @drbg DRBG state handle
1525 *
1526 * return
1527 *	0 on success
1528 */
1529static int drbg_uninstantiate(struct drbg_state *drbg)
1530{
1531	if (drbg->random_ready.func) {
1532		del_random_ready_callback(&drbg->random_ready);
1533		cancel_work_sync(&drbg->seed_work);
1534		crypto_free_rng(drbg->jent);
1535		drbg->jent = NULL;
1536	}
1537
 
 
 
 
1538	if (drbg->d_ops)
1539		drbg->d_ops->crypto_fini(drbg);
1540	drbg_dealloc_state(drbg);
1541	/* no scrubbing of test_data -- this shall survive an uninstantiate */
1542	return 0;
1543}
1544
1545/*
1546 * Helper function for setting the test data in the DRBG
1547 *
1548 * @drbg DRBG state handle
1549 * @data test data
1550 * @len test data length
1551 */
1552static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
1553				   const u8 *data, unsigned int len)
1554{
1555	struct drbg_state *drbg = crypto_rng_ctx(tfm);
1556
1557	mutex_lock(&drbg->drbg_mutex);
1558	drbg_string_fill(&drbg->test_data, data, len);
1559	mutex_unlock(&drbg->drbg_mutex);
1560}
1561
1562/***************************************************************
1563 * Kernel crypto API cipher invocations requested by DRBG
1564 ***************************************************************/
1565
1566#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1567struct sdesc {
1568	struct shash_desc shash;
1569	char ctx[];
1570};
1571
1572static int drbg_init_hash_kernel(struct drbg_state *drbg)
1573{
1574	struct sdesc *sdesc;
1575	struct crypto_shash *tfm;
1576
1577	tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1578	if (IS_ERR(tfm)) {
1579		pr_info("DRBG: could not allocate digest TFM handle: %s\n",
1580				drbg->core->backend_cra_name);
1581		return PTR_ERR(tfm);
1582	}
1583	BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1584	sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1585			GFP_KERNEL);
1586	if (!sdesc) {
1587		crypto_free_shash(tfm);
1588		return -ENOMEM;
1589	}
1590
1591	sdesc->shash.tfm = tfm;
1592	sdesc->shash.flags = 0;
1593	drbg->priv_data = sdesc;
1594
1595	return crypto_shash_alignmask(tfm);
1596}
1597
1598static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1599{
1600	struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1601	if (sdesc) {
1602		crypto_free_shash(sdesc->shash.tfm);
1603		kzfree(sdesc);
1604	}
1605	drbg->priv_data = NULL;
1606	return 0;
1607}
1608
1609static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
1610				  const unsigned char *key)
1611{
1612	struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1613
1614	crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
1615}
1616
1617static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
1618			   const struct list_head *in)
1619{
1620	struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1621	struct drbg_string *input = NULL;
1622
1623	crypto_shash_init(&sdesc->shash);
1624	list_for_each_entry(input, in, list)
1625		crypto_shash_update(&sdesc->shash, input->buf, input->len);
1626	return crypto_shash_final(&sdesc->shash, outval);
1627}
1628#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1629
1630#ifdef CONFIG_CRYPTO_DRBG_CTR
1631static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1632{
1633	struct crypto_cipher *tfm =
1634		(struct crypto_cipher *)drbg->priv_data;
1635	if (tfm)
1636		crypto_free_cipher(tfm);
1637	drbg->priv_data = NULL;
1638
1639	if (drbg->ctr_handle)
1640		crypto_free_skcipher(drbg->ctr_handle);
1641	drbg->ctr_handle = NULL;
1642
1643	if (drbg->ctr_req)
1644		skcipher_request_free(drbg->ctr_req);
1645	drbg->ctr_req = NULL;
1646
1647	kfree(drbg->ctr_null_value_buf);
1648	drbg->ctr_null_value = NULL;
1649
1650	kfree(drbg->outscratchpadbuf);
1651	drbg->outscratchpadbuf = NULL;
1652
1653	return 0;
1654}
1655
1656static int drbg_init_sym_kernel(struct drbg_state *drbg)
1657{
1658	struct crypto_cipher *tfm;
1659	struct crypto_skcipher *sk_tfm;
1660	struct skcipher_request *req;
1661	unsigned int alignmask;
1662	char ctr_name[CRYPTO_MAX_ALG_NAME];
1663
1664	tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1665	if (IS_ERR(tfm)) {
1666		pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1667				drbg->core->backend_cra_name);
1668		return PTR_ERR(tfm);
1669	}
1670	BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1671	drbg->priv_data = tfm;
1672
1673	if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1674	    drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1675		drbg_fini_sym_kernel(drbg);
1676		return -EINVAL;
1677	}
1678	sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1679	if (IS_ERR(sk_tfm)) {
1680		pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1681				ctr_name);
1682		drbg_fini_sym_kernel(drbg);
1683		return PTR_ERR(sk_tfm);
1684	}
1685	drbg->ctr_handle = sk_tfm;
1686	crypto_init_wait(&drbg->ctr_wait);
1687
1688	req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1689	if (!req) {
1690		pr_info("DRBG: could not allocate request queue\n");
1691		drbg_fini_sym_kernel(drbg);
1692		return -ENOMEM;
1693	}
1694	drbg->ctr_req = req;
1695	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
1696						CRYPTO_TFM_REQ_MAY_SLEEP,
1697					crypto_req_done, &drbg->ctr_wait);
1698
1699	alignmask = crypto_skcipher_alignmask(sk_tfm);
1700	drbg->ctr_null_value_buf = kzalloc(DRBG_CTR_NULL_LEN + alignmask,
1701					   GFP_KERNEL);
1702	if (!drbg->ctr_null_value_buf) {
1703		drbg_fini_sym_kernel(drbg);
1704		return -ENOMEM;
1705	}
1706	drbg->ctr_null_value = (u8 *)PTR_ALIGN(drbg->ctr_null_value_buf,
1707					       alignmask + 1);
1708
1709	drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
1710					 GFP_KERNEL);
1711	if (!drbg->outscratchpadbuf) {
1712		drbg_fini_sym_kernel(drbg);
1713		return -ENOMEM;
1714	}
1715	drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
1716					      alignmask + 1);
1717
 
 
 
1718	return alignmask;
1719}
1720
1721static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1722				 const unsigned char *key)
1723{
1724	struct crypto_cipher *tfm =
1725		(struct crypto_cipher *)drbg->priv_data;
1726
1727	crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1728}
1729
1730static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1731			  const struct drbg_string *in)
1732{
1733	struct crypto_cipher *tfm =
1734		(struct crypto_cipher *)drbg->priv_data;
1735
1736	/* there is only component in *in */
1737	BUG_ON(in->len < drbg_blocklen(drbg));
1738	crypto_cipher_encrypt_one(tfm, outval, in->buf);
1739	return 0;
1740}
1741
1742static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1743			      u8 *inbuf, u32 inlen,
1744			      u8 *outbuf, u32 outlen)
1745{
1746	struct scatterlist sg_in, sg_out;
 
1747	int ret;
1748
1749	sg_init_one(&sg_in, inbuf, inlen);
1750	sg_init_one(&sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
 
 
 
 
 
 
 
1751
1752	while (outlen) {
1753		u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1754
1755		/* Output buffer may not be valid for SGL, use scratchpad */
1756		skcipher_request_set_crypt(drbg->ctr_req, &sg_in, &sg_out,
1757					   cryptlen, drbg->V);
1758		ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
1759					&drbg->ctr_wait);
1760		if (ret)
1761			goto out;
1762
1763		crypto_init_wait(&drbg->ctr_wait);
1764
1765		memcpy(outbuf, drbg->outscratchpad, cryptlen);
 
1766
1767		outlen -= cryptlen;
1768		outbuf += cryptlen;
1769	}
1770	ret = 0;
1771
1772out:
1773	memzero_explicit(drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1774	return ret;
1775}
1776#endif /* CONFIG_CRYPTO_DRBG_CTR */
1777
1778/***************************************************************
1779 * Kernel crypto API interface to register DRBG
1780 ***************************************************************/
1781
1782/*
1783 * Look up the DRBG flags by given kernel crypto API cra_name
1784 * The code uses the drbg_cores definition to do this
1785 *
1786 * @cra_name kernel crypto API cra_name
1787 * @coreref reference to integer which is filled with the pointer to
1788 *  the applicable core
1789 * @pr reference for setting prediction resistance
1790 *
1791 * return: flags
1792 */
1793static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1794					 int *coreref, bool *pr)
1795{
1796	int i = 0;
1797	size_t start = 0;
1798	int len = 0;
1799
1800	*pr = true;
1801	/* disassemble the names */
1802	if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1803		start = 10;
1804		*pr = false;
1805	} else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1806		start = 8;
1807	} else {
1808		return;
1809	}
1810
1811	/* remove the first part */
1812	len = strlen(cra_driver_name) - start;
1813	for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1814		if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1815			    len)) {
1816			*coreref = i;
1817			return;
1818		}
1819	}
1820}
1821
1822static int drbg_kcapi_init(struct crypto_tfm *tfm)
1823{
1824	struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1825
1826	mutex_init(&drbg->drbg_mutex);
1827
1828	return 0;
1829}
1830
1831static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1832{
1833	drbg_uninstantiate(crypto_tfm_ctx(tfm));
1834}
1835
1836/*
1837 * Generate random numbers invoked by the kernel crypto API:
1838 * The API of the kernel crypto API is extended as follows:
1839 *
1840 * src is additional input supplied to the RNG.
1841 * slen is the length of src.
1842 * dst is the output buffer where random data is to be stored.
1843 * dlen is the length of dst.
1844 */
1845static int drbg_kcapi_random(struct crypto_rng *tfm,
1846			     const u8 *src, unsigned int slen,
1847			     u8 *dst, unsigned int dlen)
1848{
1849	struct drbg_state *drbg = crypto_rng_ctx(tfm);
1850	struct drbg_string *addtl = NULL;
1851	struct drbg_string string;
1852
1853	if (slen) {
1854		/* linked list variable is now local to allow modification */
1855		drbg_string_fill(&string, src, slen);
1856		addtl = &string;
1857	}
1858
1859	return drbg_generate_long(drbg, dst, dlen, addtl);
1860}
1861
1862/*
1863 * Seed the DRBG invoked by the kernel crypto API
1864 */
1865static int drbg_kcapi_seed(struct crypto_rng *tfm,
1866			   const u8 *seed, unsigned int slen)
1867{
1868	struct drbg_state *drbg = crypto_rng_ctx(tfm);
1869	struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1870	bool pr = false;
1871	struct drbg_string string;
1872	struct drbg_string *seed_string = NULL;
1873	int coreref = 0;
1874
1875	drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1876			      &pr);
1877	if (0 < slen) {
1878		drbg_string_fill(&string, seed, slen);
1879		seed_string = &string;
1880	}
1881
1882	return drbg_instantiate(drbg, seed_string, coreref, pr);
1883}
1884
1885/***************************************************************
1886 * Kernel module: code to load the module
1887 ***************************************************************/
1888
1889/*
1890 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1891 * of the error handling.
1892 *
1893 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1894 * as seed source of get_random_bytes does not fail.
1895 *
1896 * Note 2: There is no sensible way of testing the reseed counter
1897 * enforcement, so skip it.
1898 */
1899static inline int __init drbg_healthcheck_sanity(void)
1900{
1901	int len = 0;
1902#define OUTBUFLEN 16
1903	unsigned char buf[OUTBUFLEN];
1904	struct drbg_state *drbg = NULL;
1905	int ret = -EFAULT;
1906	int rc = -EFAULT;
1907	bool pr = false;
1908	int coreref = 0;
1909	struct drbg_string addtl;
1910	size_t max_addtllen, max_request_bytes;
1911
1912	/* only perform test in FIPS mode */
1913	if (!fips_enabled)
1914		return 0;
1915
1916#ifdef CONFIG_CRYPTO_DRBG_CTR
1917	drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1918#elif defined CONFIG_CRYPTO_DRBG_HASH
1919	drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1920#else
1921	drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1922#endif
1923
1924	drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1925	if (!drbg)
1926		return -ENOMEM;
1927
1928	mutex_init(&drbg->drbg_mutex);
1929	drbg->core = &drbg_cores[coreref];
1930	drbg->reseed_threshold = drbg_max_requests(drbg);
1931
1932	/*
1933	 * if the following tests fail, it is likely that there is a buffer
1934	 * overflow as buf is much smaller than the requested or provided
1935	 * string lengths -- in case the error handling does not succeed
1936	 * we may get an OOPS. And we want to get an OOPS as this is a
1937	 * grave bug.
1938	 */
1939
1940	max_addtllen = drbg_max_addtl(drbg);
1941	max_request_bytes = drbg_max_request_bytes(drbg);
1942	drbg_string_fill(&addtl, buf, max_addtllen + 1);
1943	/* overflow addtllen with additonal info string */
1944	len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1945	BUG_ON(0 < len);
1946	/* overflow max_bits */
1947	len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1948	BUG_ON(0 < len);
1949
1950	/* overflow max addtllen with personalization string */
1951	ret = drbg_seed(drbg, &addtl, false);
1952	BUG_ON(0 == ret);
1953	/* all tests passed */
1954	rc = 0;
1955
1956	pr_devel("DRBG: Sanity tests for failure code paths successfully "
1957		 "completed\n");
1958
1959	kfree(drbg);
1960	return rc;
1961}
1962
1963static struct rng_alg drbg_algs[22];
1964
1965/*
1966 * Fill the array drbg_algs used to register the different DRBGs
1967 * with the kernel crypto API. To fill the array, the information
1968 * from drbg_cores[] is used.
1969 */
1970static inline void __init drbg_fill_array(struct rng_alg *alg,
1971					  const struct drbg_core *core, int pr)
1972{
1973	int pos = 0;
1974	static int priority = 200;
1975
1976	memcpy(alg->base.cra_name, "stdrng", 6);
1977	if (pr) {
1978		memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
1979		pos = 8;
1980	} else {
1981		memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
1982		pos = 10;
1983	}
1984	memcpy(alg->base.cra_driver_name + pos, core->cra_name,
1985	       strlen(core->cra_name));
1986
1987	alg->base.cra_priority = priority;
1988	priority++;
1989	/*
1990	 * If FIPS mode enabled, the selected DRBG shall have the
1991	 * highest cra_priority over other stdrng instances to ensure
1992	 * it is selected.
1993	 */
1994	if (fips_enabled)
1995		alg->base.cra_priority += 200;
1996
1997	alg->base.cra_ctxsize 	= sizeof(struct drbg_state);
1998	alg->base.cra_module	= THIS_MODULE;
1999	alg->base.cra_init	= drbg_kcapi_init;
2000	alg->base.cra_exit	= drbg_kcapi_cleanup;
2001	alg->generate		= drbg_kcapi_random;
2002	alg->seed		= drbg_kcapi_seed;
2003	alg->set_ent		= drbg_kcapi_set_entropy;
2004	alg->seedsize		= 0;
2005}
2006
2007static int __init drbg_init(void)
2008{
2009	unsigned int i = 0; /* pointer to drbg_algs */
2010	unsigned int j = 0; /* pointer to drbg_cores */
2011	int ret;
2012
2013	ret = drbg_healthcheck_sanity();
2014	if (ret)
2015		return ret;
2016
2017	if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2018		pr_info("DRBG: Cannot register all DRBG types"
2019			"(slots needed: %zu, slots available: %zu)\n",
2020			ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2021		return -EFAULT;
2022	}
2023
2024	/*
2025	 * each DRBG definition can be used with PR and without PR, thus
2026	 * we instantiate each DRBG in drbg_cores[] twice.
2027	 *
2028	 * As the order of placing them into the drbg_algs array matters
2029	 * (the later DRBGs receive a higher cra_priority) we register the
2030	 * prediction resistance DRBGs first as the should not be too
2031	 * interesting.
2032	 */
2033	for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2034		drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2035	for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2036		drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2037	return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2038}
2039
2040static void __exit drbg_exit(void)
2041{
2042	crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2043}
2044
2045module_init(drbg_init);
2046module_exit(drbg_exit);
2047#ifndef CRYPTO_DRBG_HASH_STRING
2048#define CRYPTO_DRBG_HASH_STRING ""
2049#endif
2050#ifndef CRYPTO_DRBG_HMAC_STRING
2051#define CRYPTO_DRBG_HMAC_STRING ""
2052#endif
2053#ifndef CRYPTO_DRBG_CTR_STRING
2054#define CRYPTO_DRBG_CTR_STRING ""
2055#endif
2056MODULE_LICENSE("GPL");
2057MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2058MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2059		   "using following cores: "
2060		   CRYPTO_DRBG_HASH_STRING
2061		   CRYPTO_DRBG_HMAC_STRING
2062		   CRYPTO_DRBG_CTR_STRING);
2063MODULE_ALIAS_CRYPTO("stdrng");