[linux-block.git] / crypto / ansi_cprng.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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>
 */

#include <crypto/internal/cipher.h>
#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)");
subsys_initcall(prng_mod_init);
module_exit(prng_mod_fini);
MODULE_ALIAS_CRYPTO("stdrng");
MODULE_ALIAS_CRYPTO("ansi_cprng");
MODULE_IMPORT_NS(CRYPTO_INTERNAL);
Commit	Line	Data
59e0b61c	1	// SPDX-License-Identifier: GPL-2.0-or-later
17f0f4a4 NH	2	/*
	3	* PRNG: Pseudo Random Number Generator
	4	* Based on NIST Recommended PRNG From ANSI X9.31 Appendix A.2.4 using
	5	* AES 128 cipher
	6	*
	7	* (C) Neil Horman <nhorman@tuxdriver.com>
17f0f4a4 NH	8	*/
17f0f4a4 NH	9
0eb76ba2	10	#include <crypto/internal/cipher.h>
17f0f4a4 NH	11	#include <crypto/internal/rng.h>
	12	#include <linux/err.h>
	13	#include <linux/init.h>
	14	#include <linux/module.h>
	15	#include <linux/moduleparam.h>
	16	#include <linux/string.h>
	17
17f0f4a4 NH	18	#define DEFAULT_PRNG_KEY "0123456789abcdef"
	19	#define DEFAULT_PRNG_KSZ 16
	20	#define DEFAULT_BLK_SZ 16
	21	#define DEFAULT_V_SEED "zaybxcwdveuftgsh"
	22
	23	/*
	24	* Flags for the prng_context flags field
	25	*/
	26
	27	#define PRNG_FIXED_SIZE 0x1
	28	#define PRNG_NEED_RESET 0x2
	29
	30	/*
	31	* Note: DT is our counter value
	32	* I is our intermediate value
	33	* V is our seed vector
	34	* See http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
	35	* for implementation details
	36	*/
	37
	38
	39	struct prng_context {
	40	spinlock_t prng_lock;
	41	unsigned char rand_data[DEFAULT_BLK_SZ];
	42	unsigned char last_rand_data[DEFAULT_BLK_SZ];
	43	unsigned char DT[DEFAULT_BLK_SZ];
	44	unsigned char I[DEFAULT_BLK_SZ];
	45	unsigned char V[DEFAULT_BLK_SZ];
	46	u32 rand_data_valid;
	47	struct crypto_cipher *tfm;
	48	u32 flags;
	49	};
	50
	51	static int dbg;
	52
	53	static void hexdump(char note, unsigned char buf, unsigned int len)
	54	{
	55	if (dbg) {
	56	printk(KERN_CRIT "%s", note);
	57	print_hex_dump(KERN_CONT, "", DUMP_PREFIX_OFFSET,
	58	16, 1,
	59	buf, len, false);
	60	}
	61	}
	62
	63	#define dbgprint(format, args...) do {\
	64	if (dbg)\
	65	printk(format, ##args);\
	66	} while (0)
	67
	68	static void xor_vectors(unsigned char in1, unsigned char in2,
	69	unsigned char *out, unsigned int size)
	70	{
	71	int i;
	72
	73	for (i = 0; i < size; i++)
	74	out[i] = in1[i] ^ in2[i];
	75
	76	}
	77	/*
	78	* Returns DEFAULT_BLK_SZ bytes of random data per call
25985edc	79	* returns 0 if generation succeeded, <0 if something went wrong
17f0f4a4	80	*/
667b6294	81	static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
17f0f4a4 NH	82	{
	83	int i;
	84	unsigned char tmp[DEFAULT_BLK_SZ];
	85	unsigned char *output = NULL;
	86
	87
	88	dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",
	89	ctx);
	90
	91	hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ);
	92	hexdump("Input I: ", ctx->I, DEFAULT_BLK_SZ);
	93	hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);
	94
	95	/*
	96	* This algorithm is a 3 stage state machine
	97	*/
	98	for (i = 0; i < 3; i++) {
	99
	100	switch (i) {
	101	case 0:
	102	/*
	103	* Start by encrypting the counter value
	104	* This gives us an intermediate value I
	105	*/
	106	memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ);
	107	output = ctx->I;
	108	hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ);
	109	break;
	110	case 1:
	111
	112	/*
	113	* Next xor I with our secret vector V
	114	* encrypt that result to obtain our
	115	* pseudo random data which we output
	116	*/
	117	xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
	118	hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ);
	119	output = ctx->rand_data;
	120	break;
	121	case 2:
	122	/*
	123	* First check that we didn't produce the same
	124	* random data that we did last time around through this
	125	*/
	126	if (!memcmp(ctx->rand_data, ctx->last_rand_data,
	127	DEFAULT_BLK_SZ)) {
667b6294	128	if (cont_test) {
c5b1e545 NH	129	panic("cprng %p Failed repetition check!\n",
	130	ctx);
	131	}
	132
17f0f4a4 NH	133	printk(KERN_ERR
	134	"ctx %p Failed repetition check!\n",
	135	ctx);
c5b1e545	136
17f0f4a4 NH	137	ctx->flags \|= PRNG_NEED_RESET;
	138	return -EINVAL;
	139	}
	140	memcpy(ctx->last_rand_data, ctx->rand_data,
	141	DEFAULT_BLK_SZ);
	142
	143	/*
	144	* Lastly xor the random data with I
	145	* and encrypt that to obtain a new secret vector V
	146	*/
	147	xor_vectors(ctx->rand_data, ctx->I, tmp,
	148	DEFAULT_BLK_SZ);
	149	output = ctx->V;
	150	hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
	151	break;
	152	}
	153
	154
	155	/* do the encryption */
	156	crypto_cipher_encrypt_one(ctx->tfm, output, tmp);
	157
	158	}
	159
	160	/*
	161	* Now update our DT value
	162	*/
09fbf7c0	163	for (i = DEFAULT_BLK_SZ - 1; i >= 0; i--) {
17f0f4a4 NH	164	ctx->DT[i] += 1;
	165	if (ctx->DT[i] != 0)
	166	break;
	167	}
	168
	169	dbgprint("Returning new block for context %p\n", ctx);
	170	ctx->rand_data_valid = 0;
	171
	172	hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
	173	hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ);
	174	hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
	175	hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);
	176
	177	return 0;
	178	}
	179
	180	/* Our exported functions */
667b6294 NH	181	static int get_prng_bytes(char buf, size_t nbytes, struct prng_context ctx,
667b6294 NH	182	int do_cont_test)
17f0f4a4	183	{
17f0f4a4 NH	184	unsigned char *ptr = buf;
	185	unsigned int byte_count = (unsigned int)nbytes;
	186	int err;
	187
	188
ed940700	189	spin_lock_bh(&ctx->prng_lock);
17f0f4a4 NH	190
	191	err = -EINVAL;
	192	if (ctx->flags & PRNG_NEED_RESET)
	193	goto done;
	194
	195	/*
	196	* If the FIXED_SIZE flag is on, only return whole blocks of
	197	* pseudo random data
	198	*/
	199	err = -EINVAL;
	200	if (ctx->flags & PRNG_FIXED_SIZE) {
	201	if (nbytes < DEFAULT_BLK_SZ)
	202	goto done;
	203	byte_count = DEFAULT_BLK_SZ;
	204	}
	205
cde001e4 SM	206	/*
	207	* Return 0 in case of success as mandated by the kernel
	208	* crypto API interface definition.
	209	*/
	210	err = 0;
17f0f4a4 NH	211
	212	dbgprint(KERN_CRIT "getting %d random bytes for context %p\n",
	213	byte_count, ctx);
	214
	215
	216	remainder:
	217	if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
667b6294	218	if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
17f0f4a4 NH	219	memset(buf, 0, nbytes);
	220	err = -EINVAL;
	221	goto done;
	222	}
	223	}
	224
	225	/*
aa1a85db	226	* Copy any data less than an entire block
17f0f4a4 NH	227	*/
17f0f4a4 NH	228	if (byte_count < DEFAULT_BLK_SZ) {
aa1a85db	229	empty_rbuf:
714b33d1	230	while (ctx->rand_data_valid < DEFAULT_BLK_SZ) {
17f0f4a4 NH	231	*ptr = ctx->rand_data[ctx->rand_data_valid];
	232	ptr++;
	233	byte_count--;
714b33d1	234	ctx->rand_data_valid++;
17f0f4a4 NH	235	if (byte_count == 0)
	236	goto done;
	237	}
	238	}
	239
	240	/*
	241	* Now copy whole blocks
	242	*/
	243	for (; byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
aa1a85db	244	if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
667b6294	245	if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
aa1a85db JW	246	memset(buf, 0, nbytes);
	247	err = -EINVAL;
	248	goto done;
	249	}
17f0f4a4	250	}
aa1a85db JW	251	if (ctx->rand_data_valid > 0)
aa1a85db JW	252	goto empty_rbuf;
17f0f4a4 NH	253	memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
	254	ctx->rand_data_valid += DEFAULT_BLK_SZ;
	255	ptr += DEFAULT_BLK_SZ;
	256	}
	257
	258	/*
aa1a85db	259	* Now go back and get any remaining partial block
17f0f4a4 NH	260	*/
	261	if (byte_count)
	262	goto remainder;
	263
	264	done:
ed940700	265	spin_unlock_bh(&ctx->prng_lock);
17f0f4a4 NH	266	dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",
	267	err, ctx);
	268	return err;
	269	}
	270
	271	static void free_prng_context(struct prng_context *ctx)
	272	{
	273	crypto_free_cipher(ctx->tfm);
	274	}
	275
	276	static int reset_prng_context(struct prng_context *ctx,
e7c2422a HX	277	const unsigned char *key, size_t klen,
e7c2422a HX	278	const unsigned char V, const unsigned char DT)
17f0f4a4 NH	279	{
17f0f4a4 NH	280	int ret;
e7c2422a	281	const unsigned char *prng_key;
17f0f4a4	282
ed940700	283	spin_lock_bh(&ctx->prng_lock);
17f0f4a4 NH	284	ctx->flags \|= PRNG_NEED_RESET;
	285
	286	prng_key = (key != NULL) ? key : (unsigned char *)DEFAULT_PRNG_KEY;
	287
	288	if (!key)
	289	klen = DEFAULT_PRNG_KSZ;
	290
	291	if (V)
	292	memcpy(ctx->V, V, DEFAULT_BLK_SZ);
	293	else
	294	memcpy(ctx->V, DEFAULT_V_SEED, DEFAULT_BLK_SZ);
	295
	296	if (DT)
	297	memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
	298	else
	299	memset(ctx->DT, 0, DEFAULT_BLK_SZ);
	300
	301	memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
	302	memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ);
	303
17f0f4a4 NH	304	ctx->rand_data_valid = DEFAULT_BLK_SZ;
	305
	306	ret = crypto_cipher_setkey(ctx->tfm, prng_key, klen);
	307	if (ret) {
	308	dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
	309	crypto_cipher_get_flags(ctx->tfm));
17f0f4a4 NH	310	goto out;
	311	}
	312
fd09d7fa	313	ret = 0;
17f0f4a4 NH	314	ctx->flags &= ~PRNG_NEED_RESET;
17f0f4a4 NH	315	out:
ed940700	316	spin_unlock_bh(&ctx->prng_lock);
fd09d7fa	317	return ret;
17f0f4a4 NH	318	}
	319
	320	static int cprng_init(struct crypto_tfm *tfm)
	321	{
	322	struct prng_context *ctx = crypto_tfm_ctx(tfm);
	323
	324	spin_lock_init(&ctx->prng_lock);
fd09d7fa SAS	325	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
	326	if (IS_ERR(ctx->tfm)) {
	327	dbgprint(KERN_CRIT "Failed to alloc tfm for context %p\n",
	328	ctx);
	329	return PTR_ERR(ctx->tfm);
	330	}
17f0f4a4	331
d7992f42 NH	332	if (reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL) < 0)
	333	return -EINVAL;
	334
	335	/*
	336	* after allocation, we should always force the user to reset
	337	* so they don't inadvertently use the insecure default values
	338	* without specifying them intentially
	339	*/
	340	ctx->flags \|= PRNG_NEED_RESET;
	341	return 0;
17f0f4a4 NH	342	}
	343
	344	static void cprng_exit(struct crypto_tfm *tfm)
	345	{
	346	free_prng_context(crypto_tfm_ctx(tfm));
	347	}
	348
e7c2422a HX	349	static int cprng_get_random(struct crypto_rng *tfm,
	350	const u8 *src, unsigned int slen,
	351	u8 *rdata, unsigned int dlen)
17f0f4a4 NH	352	{
	353	struct prng_context *prng = crypto_rng_ctx(tfm);
	354
667b6294 NH	355	return get_prng_bytes(rdata, dlen, prng, 0);
	356	}
	357
2566578a NH	358	/*
	359	* This is the cprng_registered reset method the seed value is
	360	* interpreted as the tuple { V KEY DT}
	361	* V and KEY are required during reset, and DT is optional, detected
	362	* as being present by testing the length of the seed
	363	*/
e7c2422a HX	364	static int cprng_reset(struct crypto_rng *tfm,
e7c2422a HX	365	const u8 *seed, unsigned int slen)
17f0f4a4 NH	366	{
17f0f4a4 NH	367	struct prng_context *prng = crypto_rng_ctx(tfm);
e7c2422a HX	368	const u8 *key = seed + DEFAULT_BLK_SZ;
e7c2422a HX	369	const u8 *dt = NULL;
17f0f4a4 NH	370
	371	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
	372	return -EINVAL;
	373
2566578a NH	374	if (slen >= (2 * DEFAULT_BLK_SZ + DEFAULT_PRNG_KSZ))
	375	dt = key + DEFAULT_PRNG_KSZ;
	376
	377	reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, dt);
17f0f4a4 NH	378
	379	if (prng->flags & PRNG_NEED_RESET)
	380	return -EINVAL;
	381	return 0;
	382	}
	383
667b6294	384	#ifdef CONFIG_CRYPTO_FIPS
e7c2422a HX	385	static int fips_cprng_get_random(struct crypto_rng *tfm,
	386	const u8 *src, unsigned int slen,
	387	u8 *rdata, unsigned int dlen)
2f32bfd8 JSR	388	{
	389	struct prng_context *prng = crypto_rng_ctx(tfm);
	390
	391	return get_prng_bytes(rdata, dlen, prng, 1);
	392	}
	393
e7c2422a HX	394	static int fips_cprng_reset(struct crypto_rng *tfm,
e7c2422a HX	395	const u8 *seed, unsigned int slen)
2f32bfd8 JSR	396	{
2f32bfd8 JSR	397	u8 rdata[DEFAULT_BLK_SZ];
e7c2422a	398	const u8 *key = seed + DEFAULT_BLK_SZ;
2f32bfd8 JSR	399	int rc;
	400
	401	struct prng_context *prng = crypto_rng_ctx(tfm);
	402
505172e1 JW	403	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
	404	return -EINVAL;
	405
	406	/* fips strictly requires seed != key */
	407	if (!memcmp(seed, key, DEFAULT_PRNG_KSZ))
	408	return -EINVAL;
	409
2f32bfd8 JSR	410	rc = cprng_reset(tfm, seed, slen);
	411
	412	if (!rc)
	413	goto out;
	414
	415	/* this primes our continuity test */
	416	rc = get_prng_bytes(rdata, DEFAULT_BLK_SZ, prng, 0);
	417	prng->rand_data_valid = DEFAULT_BLK_SZ;
	418
	419	out:
	420	return rc;
	421	}
8fc229a5	422	#endif
2f32bfd8	423
e7c2422a HX	424	static struct rng_alg rng_algs[] = { {
	425	.generate = cprng_get_random,
	426	.seed = cprng_reset,
	427	.seedsize = DEFAULT_PRNG_KSZ + 2 * DEFAULT_BLK_SZ,
	428	.base = {
	429	.cra_name = "stdrng",
	430	.cra_driver_name = "ansi_cprng",
	431	.cra_priority = 100,
	432	.cra_ctxsize = sizeof(struct prng_context),
	433	.cra_module = THIS_MODULE,
	434	.cra_init = cprng_init,
	435	.cra_exit = cprng_exit,
8fc229a5 JK	436	}
	437	#ifdef CONFIG_CRYPTO_FIPS
	438	}, {
e7c2422a HX	439	.generate = fips_cprng_get_random,
	440	.seed = fips_cprng_reset,
	441	.seedsize = DEFAULT_PRNG_KSZ + 2 * DEFAULT_BLK_SZ,
	442	.base = {
	443	.cra_name = "fips(ansi_cprng)",
	444	.cra_driver_name = "fips_ansi_cprng",
	445	.cra_priority = 300,
	446	.cra_ctxsize = sizeof(struct prng_context),
	447	.cra_module = THIS_MODULE,
	448	.cra_init = cprng_init,
	449	.cra_exit = cprng_exit,
667b6294	450	}
667b6294	451	#endif
8fc229a5	452	} };
17f0f4a4 NH	453
	454	/* Module initalization */
	455	static int __init prng_mod_init(void)
	456	{
e7c2422a	457	return crypto_register_rngs(rng_algs, ARRAY_SIZE(rng_algs));
17f0f4a4 NH	458	}
	459
	460	static void __exit prng_mod_fini(void)
	461	{
e7c2422a	462	crypto_unregister_rngs(rng_algs, ARRAY_SIZE(rng_algs));
17f0f4a4 NH	463	}
	464
	465	MODULE_LICENSE("GPL");
	466	MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
	467	MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
	468	module_param(dbg, int, 0);
	469	MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
c4741b23	470	subsys_initcall(prng_mod_init);
17f0f4a4	471	module_exit(prng_mod_fini);
5d26a105	472	MODULE_ALIAS_CRYPTO("stdrng");
3e14dcf7	473	MODULE_ALIAS_CRYPTO("ansi_cprng");
0eb76ba2	474	MODULE_IMPORT_NS(CRYPTO_INTERNAL);