[deliverable/linux.git] / crypto / ansi_cprng.c

/*
 * PRNG: Pseudo Random Number Generator
 *       Based on NIST Recommended PRNG From ANSI X9.31 Appendix A.2.4 using
 *       AES 128 cipher
 *
 *  (C) Neil Horman <nhorman@tuxdriver.com>
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License as published by the
 *  Free Software Foundation; either version 2 of the License, or (at your
 *  any later version.
 *
 *
 */

#include <crypto/internal/rng.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/string.h>

#define DEFAULT_PRNG_KEY "0123456789abcdef"
#define DEFAULT_PRNG_KSZ 16
#define DEFAULT_BLK_SZ 16
#define DEFAULT_V_SEED "zaybxcwdveuftgsh"

/*
 * Flags for the prng_context flags field
 */

#define PRNG_FIXED_SIZE 0x1
#define PRNG_NEED_RESET 0x2

/*
 * Note: DT is our counter value
 *	 I is our intermediate value
 *	 V is our seed vector
 * See http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
 * for implementation details
 */


struct prng_context {
	spinlock_t prng_lock;
	unsigned char rand_data[DEFAULT_BLK_SZ];
	unsigned char last_rand_data[DEFAULT_BLK_SZ];
	unsigned char DT[DEFAULT_BLK_SZ];
	unsigned char I[DEFAULT_BLK_SZ];
	unsigned char V[DEFAULT_BLK_SZ];
	u32 rand_data_valid;
	struct crypto_cipher *tfm;
	u32 flags;
};

static int dbg;

static void hexdump(char *note, unsigned char *buf, unsigned int len)
{
	if (dbg) {
		printk(KERN_CRIT "%s", note);
		print_hex_dump(KERN_CONT, "", DUMP_PREFIX_OFFSET,
				16, 1,
				buf, len, false);
	}
}

#define dbgprint(format, args...) do {\
if (dbg)\
	printk(format, ##args);\
} while (0)

static void xor_vectors(unsigned char *in1, unsigned char *in2,
			unsigned char *out, unsigned int size)
{
	int i;

	for (i = 0; i < size; i++)
		out[i] = in1[i] ^ in2[i];

}
/*
 * Returns DEFAULT_BLK_SZ bytes of random data per call
 * returns 0 if generation succeeded, <0 if something went wrong
 */
static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
{
	int i;
	unsigned char tmp[DEFAULT_BLK_SZ];
	unsigned char *output = NULL;


	dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",
		ctx);

	hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ);
	hexdump("Input I: ", ctx->I, DEFAULT_BLK_SZ);
	hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);

	/*
	 * This algorithm is a 3 stage state machine
	 */
	for (i = 0; i < 3; i++) {

		switch (i) {
		case 0:
			/*
			 * Start by encrypting the counter value
			 * This gives us an intermediate value I
			 */
			memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ);
			output = ctx->I;
			hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ);
			break;
		case 1:

			/*
			 * Next xor I with our secret vector V
			 * encrypt that result to obtain our
			 * pseudo random data which we output
			 */
			xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
			hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ);
			output = ctx->rand_data;
			break;
		case 2:
			/*
			 * First check that we didn't produce the same
			 * random data that we did last time around through this
			 */
			if (!memcmp(ctx->rand_data, ctx->last_rand_data,
					DEFAULT_BLK_SZ)) {
				if (cont_test) {
					panic("cprng %p Failed repetition check!\n",
						ctx);
				}

				printk(KERN_ERR
					"ctx %p Failed repetition check!\n",
					ctx);

				ctx->flags |= PRNG_NEED_RESET;
				return -EINVAL;
			}
			memcpy(ctx->last_rand_data, ctx->rand_data,
				DEFAULT_BLK_SZ);

			/*
			 * Lastly xor the random data with I
			 * and encrypt that to obtain a new secret vector V
			 */
			xor_vectors(ctx->rand_data, ctx->I, tmp,
				DEFAULT_BLK_SZ);
			output = ctx->V;
			hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
			break;
		}


		/* do the encryption */
		crypto_cipher_encrypt_one(ctx->tfm, output, tmp);

	}

	/*
	 * Now update our DT value
	 */
	for (i = DEFAULT_BLK_SZ - 1; i >= 0; i--) {
		ctx->DT[i] += 1;
		if (ctx->DT[i] != 0)
			break;
	}

	dbgprint("Returning new block for context %p\n", ctx);
	ctx->rand_data_valid = 0;

	hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
	hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ);
	hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
	hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);

	return 0;
}

/* Our exported functions */
static int get_prng_bytes(char *buf, size_t nbytes, struct prng_context *ctx,
				int do_cont_test)
{
	unsigned char *ptr = buf;
	unsigned int byte_count = (unsigned int)nbytes;
	int err;


	spin_lock_bh(&ctx->prng_lock);

	err = -EINVAL;
	if (ctx->flags & PRNG_NEED_RESET)
		goto done;

	/*
	 * If the FIXED_SIZE flag is on, only return whole blocks of
	 * pseudo random data
	 */
	err = -EINVAL;
	if (ctx->flags & PRNG_FIXED_SIZE) {
		if (nbytes < DEFAULT_BLK_SZ)
			goto done;
		byte_count = DEFAULT_BLK_SZ;
	}

	/*
	 * Return 0 in case of success as mandated by the kernel
	 * crypto API interface definition.
	 */
	err = 0;

	dbgprint(KERN_CRIT "getting %d random bytes for context %p\n",
		byte_count, ctx);


remainder:
	if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
		if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
			memset(buf, 0, nbytes);
			err = -EINVAL;
			goto done;
		}
	}

	/*
	 * Copy any data less than an entire block
	 */
	if (byte_count < DEFAULT_BLK_SZ) {
empty_rbuf:
		while (ctx->rand_data_valid < DEFAULT_BLK_SZ) {
			*ptr = ctx->rand_data[ctx->rand_data_valid];
			ptr++;
			byte_count--;
			ctx->rand_data_valid++;
			if (byte_count == 0)
				goto done;
		}
	}

	/*
	 * Now copy whole blocks
	 */
	for (; byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
		if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
			if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
				memset(buf, 0, nbytes);
				err = -EINVAL;
				goto done;
			}
		}
		if (ctx->rand_data_valid > 0)
			goto empty_rbuf;
		memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
		ctx->rand_data_valid += DEFAULT_BLK_SZ;
		ptr += DEFAULT_BLK_SZ;
	}

	/*
	 * Now go back and get any remaining partial block
	 */
	if (byte_count)
		goto remainder;

done:
	spin_unlock_bh(&ctx->prng_lock);
	dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",
		err, ctx);
	return err;
}

static void free_prng_context(struct prng_context *ctx)
{
	crypto_free_cipher(ctx->tfm);
}

static int reset_prng_context(struct prng_context *ctx,
			      const unsigned char *key, size_t klen,
			      const unsigned char *V, const unsigned char *DT)
{
	int ret;
	const unsigned char *prng_key;

	spin_lock_bh(&ctx->prng_lock);
	ctx->flags |= PRNG_NEED_RESET;

	prng_key = (key != NULL) ? key : (unsigned char *)DEFAULT_PRNG_KEY;

	if (!key)
		klen = DEFAULT_PRNG_KSZ;

	if (V)
		memcpy(ctx->V, V, DEFAULT_BLK_SZ);
	else
		memcpy(ctx->V, DEFAULT_V_SEED, DEFAULT_BLK_SZ);

	if (DT)
		memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
	else
		memset(ctx->DT, 0, DEFAULT_BLK_SZ);

	memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
	memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ);

	ctx->rand_data_valid = DEFAULT_BLK_SZ;

	ret = crypto_cipher_setkey(ctx->tfm, prng_key, klen);
	if (ret) {
		dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
			crypto_cipher_get_flags(ctx->tfm));
		goto out;
	}

	ret = 0;
	ctx->flags &= ~PRNG_NEED_RESET;
out:
	spin_unlock_bh(&ctx->prng_lock);
	return ret;
}

static int cprng_init(struct crypto_tfm *tfm)
{
	struct prng_context *ctx = crypto_tfm_ctx(tfm);

	spin_lock_init(&ctx->prng_lock);
	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
	if (IS_ERR(ctx->tfm)) {
		dbgprint(KERN_CRIT "Failed to alloc tfm for context %p\n",
				ctx);
		return PTR_ERR(ctx->tfm);
	}

	if (reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL) < 0)
		return -EINVAL;

	/*
	 * after allocation, we should always force the user to reset
	 * so they don't inadvertently use the insecure default values
	 * without specifying them intentially
	 */
	ctx->flags |= PRNG_NEED_RESET;
	return 0;
}

static void cprng_exit(struct crypto_tfm *tfm)
{
	free_prng_context(crypto_tfm_ctx(tfm));
}

static int cprng_get_random(struct crypto_rng *tfm,
			    const u8 *src, unsigned int slen,
			    u8 *rdata, unsigned int dlen)
{
	struct prng_context *prng = crypto_rng_ctx(tfm);

	return get_prng_bytes(rdata, dlen, prng, 0);
}

/*
 *  This is the cprng_registered reset method the seed value is
 *  interpreted as the tuple { V KEY DT}
 *  V and KEY are required during reset, and DT is optional, detected
 *  as being present by testing the length of the seed
 */
static int cprng_reset(struct crypto_rng *tfm,
		       const u8 *seed, unsigned int slen)
{
	struct prng_context *prng = crypto_rng_ctx(tfm);
	const u8 *key = seed + DEFAULT_BLK_SZ;
	const u8 *dt = NULL;

	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
		return -EINVAL;

	if (slen >= (2 * DEFAULT_BLK_SZ + DEFAULT_PRNG_KSZ))
		dt = key + DEFAULT_PRNG_KSZ;

	reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, dt);

	if (prng->flags & PRNG_NEED_RESET)
		return -EINVAL;
	return 0;
}

#ifdef CONFIG_CRYPTO_FIPS
static int fips_cprng_get_random(struct crypto_rng *tfm,
				 const u8 *src, unsigned int slen,
				 u8 *rdata, unsigned int dlen)
{
	struct prng_context *prng = crypto_rng_ctx(tfm);

	return get_prng_bytes(rdata, dlen, prng, 1);
}

static int fips_cprng_reset(struct crypto_rng *tfm,
			    const u8 *seed, unsigned int slen)
{
	u8 rdata[DEFAULT_BLK_SZ];
	const u8 *key = seed + DEFAULT_BLK_SZ;
	int rc;

	struct prng_context *prng = crypto_rng_ctx(tfm);

	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
		return -EINVAL;

	/* fips strictly requires seed != key */
	if (!memcmp(seed, key, DEFAULT_PRNG_KSZ))
		return -EINVAL;

	rc = cprng_reset(tfm, seed, slen);

	if (!rc)
		goto out;

	/* this primes our continuity test */
	rc = get_prng_bytes(rdata, DEFAULT_BLK_SZ, prng, 0);
	prng->rand_data_valid = DEFAULT_BLK_SZ;

out:
	return rc;
}
#endif

static struct rng_alg rng_algs[] = { {
	.generate		= cprng_get_random,
	.seed			= cprng_reset,
	.seedsize		= DEFAULT_PRNG_KSZ + 2 * DEFAULT_BLK_SZ,
	.base			=	{
		.cra_name		= "stdrng",
		.cra_driver_name	= "ansi_cprng",
		.cra_priority		= 100,
		.cra_ctxsize		= sizeof(struct prng_context),
		.cra_module		= THIS_MODULE,
		.cra_init		= cprng_init,
		.cra_exit		= cprng_exit,
	}
#ifdef CONFIG_CRYPTO_FIPS
}, {
	.generate		= fips_cprng_get_random,
	.seed			= fips_cprng_reset,
	.seedsize		= DEFAULT_PRNG_KSZ + 2 * DEFAULT_BLK_SZ,
	.base			=	{
		.cra_name		= "fips(ansi_cprng)",
		.cra_driver_name	= "fips_ansi_cprng",
		.cra_priority		= 300,
		.cra_ctxsize		= sizeof(struct prng_context),
		.cra_module		= THIS_MODULE,
		.cra_init		= cprng_init,
		.cra_exit		= cprng_exit,
	}
#endif
} };

/* Module initalization */
static int __init prng_mod_init(void)
{
	return crypto_register_rngs(rng_algs, ARRAY_SIZE(rng_algs));
}

static void __exit prng_mod_fini(void)
{
	crypto_unregister_rngs(rng_algs, ARRAY_SIZE(rng_algs));
}

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
module_param(dbg, int, 0);
MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
module_init(prng_mod_init);
module_exit(prng_mod_fini);
MODULE_ALIAS_CRYPTO("stdrng");
MODULE_ALIAS_CRYPTO("ansi_cprng");
Commit	Line	Data
17f0f4a4 NH	1	/*
	2	* PRNG: Pseudo Random Number Generator
	3	* Based on NIST Recommended PRNG From ANSI X9.31 Appendix A.2.4 using
	4	* AES 128 cipher
	5	*
	6	* (C) Neil Horman <nhorman@tuxdriver.com>
	7	*
	8	* This program is free software; you can redistribute it and/or modify it
	9	* under the terms of the GNU General Public License as published by the
	10	* Free Software Foundation; either version 2 of the License, or (at your
	11	* any later version.
	12	*
	13	*
	14	*/
	15
	16	#include <crypto/internal/rng.h>
	17	#include <linux/err.h>
	18	#include <linux/init.h>
	19	#include <linux/module.h>
	20	#include <linux/moduleparam.h>
	21	#include <linux/string.h>
	22
17f0f4a4 NH	23	#define DEFAULT_PRNG_KEY "0123456789abcdef"
	24	#define DEFAULT_PRNG_KSZ 16
	25	#define DEFAULT_BLK_SZ 16
	26	#define DEFAULT_V_SEED "zaybxcwdveuftgsh"
	27
	28	/*
	29	* Flags for the prng_context flags field
	30	*/
	31
	32	#define PRNG_FIXED_SIZE 0x1
	33	#define PRNG_NEED_RESET 0x2
	34
	35	/*
	36	* Note: DT is our counter value
	37	* I is our intermediate value
	38	* V is our seed vector
	39	* See http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
	40	* for implementation details
	41	*/
	42
	43
	44	struct prng_context {
	45	spinlock_t prng_lock;
	46	unsigned char rand_data[DEFAULT_BLK_SZ];
	47	unsigned char last_rand_data[DEFAULT_BLK_SZ];
	48	unsigned char DT[DEFAULT_BLK_SZ];
	49	unsigned char I[DEFAULT_BLK_SZ];
	50	unsigned char V[DEFAULT_BLK_SZ];
	51	u32 rand_data_valid;
	52	struct crypto_cipher *tfm;
	53	u32 flags;
	54	};
	55
	56	static int dbg;
	57
	58	static void hexdump(char note, unsigned char buf, unsigned int len)
	59	{
	60	if (dbg) {
	61	printk(KERN_CRIT "%s", note);
	62	print_hex_dump(KERN_CONT, "", DUMP_PREFIX_OFFSET,
	63	16, 1,
	64	buf, len, false);
	65	}
	66	}
	67
	68	#define dbgprint(format, args...) do {\
	69	if (dbg)\
	70	printk(format, ##args);\
	71	} while (0)
	72
	73	static void xor_vectors(unsigned char in1, unsigned char in2,
	74	unsigned char *out, unsigned int size)
	75	{
	76	int i;
	77
	78	for (i = 0; i < size; i++)
	79	out[i] = in1[i] ^ in2[i];
	80
	81	}
	82	/*
	83	* Returns DEFAULT_BLK_SZ bytes of random data per call
25985edc	84	* returns 0 if generation succeeded, <0 if something went wrong
17f0f4a4	85	*/
667b6294	86	static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
17f0f4a4 NH	87	{
	88	int i;
	89	unsigned char tmp[DEFAULT_BLK_SZ];
	90	unsigned char *output = NULL;
	91
	92
	93	dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",
	94	ctx);
	95
	96	hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ);
	97	hexdump("Input I: ", ctx->I, DEFAULT_BLK_SZ);
	98	hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);
	99
	100	/*
	101	* This algorithm is a 3 stage state machine
	102	*/
	103	for (i = 0; i < 3; i++) {
	104
	105	switch (i) {
	106	case 0:
	107	/*
	108	* Start by encrypting the counter value
	109	* This gives us an intermediate value I
	110	*/
	111	memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ);
	112	output = ctx->I;
	113	hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ);
	114	break;
	115	case 1:
	116
	117	/*
	118	* Next xor I with our secret vector V
	119	* encrypt that result to obtain our
	120	* pseudo random data which we output
	121	*/
	122	xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
	123	hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ);
	124	output = ctx->rand_data;
	125	break;
	126	case 2:
	127	/*
	128	* First check that we didn't produce the same
	129	* random data that we did last time around through this
	130	*/
	131	if (!memcmp(ctx->rand_data, ctx->last_rand_data,
	132	DEFAULT_BLK_SZ)) {
667b6294	133	if (cont_test) {
c5b1e545 NH	134	panic("cprng %p Failed repetition check!\n",
	135	ctx);
	136	}
	137
17f0f4a4 NH	138	printk(KERN_ERR
	139	"ctx %p Failed repetition check!\n",
	140	ctx);
c5b1e545	141
17f0f4a4 NH	142	ctx->flags \|= PRNG_NEED_RESET;
	143	return -EINVAL;
	144	}
	145	memcpy(ctx->last_rand_data, ctx->rand_data,
	146	DEFAULT_BLK_SZ);
	147
	148	/*
	149	* Lastly xor the random data with I
	150	* and encrypt that to obtain a new secret vector V
	151	*/
	152	xor_vectors(ctx->rand_data, ctx->I, tmp,
	153	DEFAULT_BLK_SZ);
	154	output = ctx->V;
	155	hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
	156	break;
	157	}
	158
	159
	160	/* do the encryption */
	161	crypto_cipher_encrypt_one(ctx->tfm, output, tmp);
	162
	163	}
	164
	165	/*
	166	* Now update our DT value
	167	*/
09fbf7c0	168	for (i = DEFAULT_BLK_SZ - 1; i >= 0; i--) {
17f0f4a4 NH	169	ctx->DT[i] += 1;
	170	if (ctx->DT[i] != 0)
	171	break;
	172	}
	173
	174	dbgprint("Returning new block for context %p\n", ctx);
	175	ctx->rand_data_valid = 0;
	176
	177	hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
	178	hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ);
	179	hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
	180	hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);
	181
	182	return 0;
	183	}
	184
	185	/* Our exported functions */
667b6294 NH	186	static int get_prng_bytes(char buf, size_t nbytes, struct prng_context ctx,
667b6294 NH	187	int do_cont_test)
17f0f4a4	188	{
17f0f4a4 NH	189	unsigned char *ptr = buf;
	190	unsigned int byte_count = (unsigned int)nbytes;
	191	int err;
	192
	193
ed940700	194	spin_lock_bh(&ctx->prng_lock);
17f0f4a4 NH	195
	196	err = -EINVAL;
	197	if (ctx->flags & PRNG_NEED_RESET)
	198	goto done;
	199
	200	/*
	201	* If the FIXED_SIZE flag is on, only return whole blocks of
	202	* pseudo random data
	203	*/
	204	err = -EINVAL;
	205	if (ctx->flags & PRNG_FIXED_SIZE) {
	206	if (nbytes < DEFAULT_BLK_SZ)
	207	goto done;
	208	byte_count = DEFAULT_BLK_SZ;
	209	}
	210
cde001e4 SM	211	/*
	212	* Return 0 in case of success as mandated by the kernel
	213	* crypto API interface definition.
	214	*/
	215	err = 0;
17f0f4a4 NH	216
	217	dbgprint(KERN_CRIT "getting %d random bytes for context %p\n",
	218	byte_count, ctx);
	219
	220
	221	remainder:
	222	if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
667b6294	223	if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
17f0f4a4 NH	224	memset(buf, 0, nbytes);
	225	err = -EINVAL;
	226	goto done;
	227	}
	228	}
	229
	230	/*
aa1a85db	231	* Copy any data less than an entire block
17f0f4a4 NH	232	*/
17f0f4a4 NH	233	if (byte_count < DEFAULT_BLK_SZ) {
aa1a85db	234	empty_rbuf:
714b33d1	235	while (ctx->rand_data_valid < DEFAULT_BLK_SZ) {
17f0f4a4 NH	236	*ptr = ctx->rand_data[ctx->rand_data_valid];
	237	ptr++;
	238	byte_count--;
714b33d1	239	ctx->rand_data_valid++;
17f0f4a4 NH	240	if (byte_count == 0)
	241	goto done;
	242	}
	243	}
	244
	245	/*
	246	* Now copy whole blocks
	247	*/
	248	for (; byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
aa1a85db	249	if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
667b6294	250	if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
aa1a85db JW	251	memset(buf, 0, nbytes);
	252	err = -EINVAL;
	253	goto done;
	254	}
17f0f4a4	255	}
aa1a85db JW	256	if (ctx->rand_data_valid > 0)
aa1a85db JW	257	goto empty_rbuf;
17f0f4a4 NH	258	memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
	259	ctx->rand_data_valid += DEFAULT_BLK_SZ;
	260	ptr += DEFAULT_BLK_SZ;
	261	}
	262
	263	/*
aa1a85db	264	* Now go back and get any remaining partial block
17f0f4a4 NH	265	*/
	266	if (byte_count)
	267	goto remainder;
	268
	269	done:
ed940700	270	spin_unlock_bh(&ctx->prng_lock);
17f0f4a4 NH	271	dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",
	272	err, ctx);
	273	return err;
	274	}
	275
	276	static void free_prng_context(struct prng_context *ctx)
	277	{
	278	crypto_free_cipher(ctx->tfm);
	279	}
	280
	281	static int reset_prng_context(struct prng_context *ctx,
e7c2422a HX	282	const unsigned char *key, size_t klen,
e7c2422a HX	283	const unsigned char V, const unsigned char DT)
17f0f4a4 NH	284	{
17f0f4a4 NH	285	int ret;
e7c2422a	286	const unsigned char *prng_key;
17f0f4a4	287
ed940700	288	spin_lock_bh(&ctx->prng_lock);
17f0f4a4 NH	289	ctx->flags \|= PRNG_NEED_RESET;
	290
	291	prng_key = (key != NULL) ? key : (unsigned char *)DEFAULT_PRNG_KEY;
	292
	293	if (!key)
	294	klen = DEFAULT_PRNG_KSZ;
	295
	296	if (V)
	297	memcpy(ctx->V, V, DEFAULT_BLK_SZ);
	298	else
	299	memcpy(ctx->V, DEFAULT_V_SEED, DEFAULT_BLK_SZ);
	300
	301	if (DT)
	302	memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
	303	else
	304	memset(ctx->DT, 0, DEFAULT_BLK_SZ);
	305
	306	memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
	307	memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ);
	308
17f0f4a4 NH	309	ctx->rand_data_valid = DEFAULT_BLK_SZ;
	310
	311	ret = crypto_cipher_setkey(ctx->tfm, prng_key, klen);
	312	if (ret) {
	313	dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
	314	crypto_cipher_get_flags(ctx->tfm));
17f0f4a4 NH	315	goto out;
	316	}
	317
fd09d7fa	318	ret = 0;
17f0f4a4 NH	319	ctx->flags &= ~PRNG_NEED_RESET;
17f0f4a4 NH	320	out:
ed940700	321	spin_unlock_bh(&ctx->prng_lock);
fd09d7fa	322	return ret;
17f0f4a4 NH	323	}
	324
	325	static int cprng_init(struct crypto_tfm *tfm)
	326	{
	327	struct prng_context *ctx = crypto_tfm_ctx(tfm);
	328
	329	spin_lock_init(&ctx->prng_lock);
fd09d7fa SAS	330	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
	331	if (IS_ERR(ctx->tfm)) {
	332	dbgprint(KERN_CRIT "Failed to alloc tfm for context %p\n",
	333	ctx);
	334	return PTR_ERR(ctx->tfm);
	335	}
17f0f4a4	336
d7992f42 NH	337	if (reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL) < 0)
	338	return -EINVAL;
	339
	340	/*
	341	* after allocation, we should always force the user to reset
	342	* so they don't inadvertently use the insecure default values
	343	* without specifying them intentially
	344	*/
	345	ctx->flags \|= PRNG_NEED_RESET;
	346	return 0;
17f0f4a4 NH	347	}
	348
	349	static void cprng_exit(struct crypto_tfm *tfm)
	350	{
	351	free_prng_context(crypto_tfm_ctx(tfm));
	352	}
	353
e7c2422a HX	354	static int cprng_get_random(struct crypto_rng *tfm,
	355	const u8 *src, unsigned int slen,
	356	u8 *rdata, unsigned int dlen)
17f0f4a4 NH	357	{
	358	struct prng_context *prng = crypto_rng_ctx(tfm);
	359
667b6294 NH	360	return get_prng_bytes(rdata, dlen, prng, 0);
	361	}
	362
2566578a NH	363	/*
	364	* This is the cprng_registered reset method the seed value is
	365	* interpreted as the tuple { V KEY DT}
	366	* V and KEY are required during reset, and DT is optional, detected
	367	* as being present by testing the length of the seed
	368	*/
e7c2422a HX	369	static int cprng_reset(struct crypto_rng *tfm,
e7c2422a HX	370	const u8 *seed, unsigned int slen)
17f0f4a4 NH	371	{
17f0f4a4 NH	372	struct prng_context *prng = crypto_rng_ctx(tfm);
e7c2422a HX	373	const u8 *key = seed + DEFAULT_BLK_SZ;
e7c2422a HX	374	const u8 *dt = NULL;
17f0f4a4 NH	375
	376	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
	377	return -EINVAL;
	378
2566578a NH	379	if (slen >= (2 * DEFAULT_BLK_SZ + DEFAULT_PRNG_KSZ))
	380	dt = key + DEFAULT_PRNG_KSZ;
	381
	382	reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, dt);
17f0f4a4 NH	383
	384	if (prng->flags & PRNG_NEED_RESET)
	385	return -EINVAL;
	386	return 0;
	387	}
	388
667b6294	389	#ifdef CONFIG_CRYPTO_FIPS
e7c2422a HX	390	static int fips_cprng_get_random(struct crypto_rng *tfm,
	391	const u8 *src, unsigned int slen,
	392	u8 *rdata, unsigned int dlen)
2f32bfd8 JSR	393	{
	394	struct prng_context *prng = crypto_rng_ctx(tfm);
	395
	396	return get_prng_bytes(rdata, dlen, prng, 1);
	397	}
	398
e7c2422a HX	399	static int fips_cprng_reset(struct crypto_rng *tfm,
e7c2422a HX	400	const u8 *seed, unsigned int slen)
2f32bfd8 JSR	401	{
2f32bfd8 JSR	402	u8 rdata[DEFAULT_BLK_SZ];
e7c2422a	403	const u8 *key = seed + DEFAULT_BLK_SZ;
2f32bfd8 JSR	404	int rc;
	405
	406	struct prng_context *prng = crypto_rng_ctx(tfm);
	407
505172e1 JW	408	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
	409	return -EINVAL;
	410
	411	/* fips strictly requires seed != key */
	412	if (!memcmp(seed, key, DEFAULT_PRNG_KSZ))
	413	return -EINVAL;
	414
2f32bfd8 JSR	415	rc = cprng_reset(tfm, seed, slen);
	416
	417	if (!rc)
	418	goto out;
	419
	420	/* this primes our continuity test */
	421	rc = get_prng_bytes(rdata, DEFAULT_BLK_SZ, prng, 0);
	422	prng->rand_data_valid = DEFAULT_BLK_SZ;
	423
	424	out:
	425	return rc;
	426	}
8fc229a5	427	#endif
2f32bfd8	428
e7c2422a HX	429	static struct rng_alg rng_algs[] = { {
	430	.generate = cprng_get_random,
	431	.seed = cprng_reset,
	432	.seedsize = DEFAULT_PRNG_KSZ + 2 * DEFAULT_BLK_SZ,
	433	.base = {
	434	.cra_name = "stdrng",
	435	.cra_driver_name = "ansi_cprng",
	436	.cra_priority = 100,
	437	.cra_ctxsize = sizeof(struct prng_context),
	438	.cra_module = THIS_MODULE,
	439	.cra_init = cprng_init,
	440	.cra_exit = cprng_exit,
8fc229a5 JK	441	}
	442	#ifdef CONFIG_CRYPTO_FIPS
	443	}, {
e7c2422a HX	444	.generate = fips_cprng_get_random,
	445	.seed = fips_cprng_reset,
	446	.seedsize = DEFAULT_PRNG_KSZ + 2 * DEFAULT_BLK_SZ,
	447	.base = {
	448	.cra_name = "fips(ansi_cprng)",
	449	.cra_driver_name = "fips_ansi_cprng",
	450	.cra_priority = 300,
	451	.cra_ctxsize = sizeof(struct prng_context),
	452	.cra_module = THIS_MODULE,
	453	.cra_init = cprng_init,
	454	.cra_exit = cprng_exit,
667b6294	455	}
667b6294	456	#endif
8fc229a5	457	} };
17f0f4a4 NH	458
	459	/* Module initalization */
	460	static int __init prng_mod_init(void)
	461	{
e7c2422a	462	return crypto_register_rngs(rng_algs, ARRAY_SIZE(rng_algs));
17f0f4a4 NH	463	}
	464
	465	static void __exit prng_mod_fini(void)
	466	{
e7c2422a	467	crypto_unregister_rngs(rng_algs, ARRAY_SIZE(rng_algs));
17f0f4a4 NH	468	}
	469
	470	MODULE_LICENSE("GPL");
	471	MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
	472	MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
	473	module_param(dbg, int, 0);
	474	MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
	475	module_init(prng_mod_init);
	476	module_exit(prng_mod_fini);
5d26a105	477	MODULE_ALIAS_CRYPTO("stdrng");
3e14dcf7	478	MODULE_ALIAS_CRYPTO("ansi_cprng");