[linux-2.6-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/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");
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	*/
	9
	10	#include <crypto/internal/rng.h>
	11	#include <linux/err.h>
	12	#include <linux/init.h>
	13	#include <linux/module.h>
	14	#include <linux/moduleparam.h>
	15	#include <linux/string.h>
	16
17f0f4a4 NH	17	#define DEFAULT_PRNG_KEY "0123456789abcdef"
	18	#define DEFAULT_PRNG_KSZ 16
	19	#define DEFAULT_BLK_SZ 16
	20	#define DEFAULT_V_SEED "zaybxcwdveuftgsh"
	21
	22	/*
	23	* Flags for the prng_context flags field
	24	*/
	25
	26	#define PRNG_FIXED_SIZE 0x1
	27	#define PRNG_NEED_RESET 0x2
	28
	29	/*
	30	* Note: DT is our counter value
	31	* I is our intermediate value
	32	* V is our seed vector
	33	* See http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
	34	* for implementation details
	35	*/
	36
	37
	38	struct prng_context {
	39	spinlock_t prng_lock;
	40	unsigned char rand_data[DEFAULT_BLK_SZ];
	41	unsigned char last_rand_data[DEFAULT_BLK_SZ];
	42	unsigned char DT[DEFAULT_BLK_SZ];
	43	unsigned char I[DEFAULT_BLK_SZ];
	44	unsigned char V[DEFAULT_BLK_SZ];
	45	u32 rand_data_valid;
	46	struct crypto_cipher *tfm;
	47	u32 flags;
	48	};
	49
	50	static int dbg;
	51
	52	static void hexdump(char note, unsigned char buf, unsigned int len)
	53	{
	54	if (dbg) {
	55	printk(KERN_CRIT "%s", note);
	56	print_hex_dump(KERN_CONT, "", DUMP_PREFIX_OFFSET,
	57	16, 1,
	58	buf, len, false);
	59	}
	60	}
	61
	62	#define dbgprint(format, args...) do {\
	63	if (dbg)\
	64	printk(format, ##args);\
	65	} while (0)
	66
	67	static void xor_vectors(unsigned char in1, unsigned char in2,
	68	unsigned char *out, unsigned int size)
	69	{
	70	int i;
	71
	72	for (i = 0; i < size; i++)
	73	out[i] = in1[i] ^ in2[i];
	74
	75	}
	76	/*
	77	* Returns DEFAULT_BLK_SZ bytes of random data per call
25985edc	78	* returns 0 if generation succeeded, <0 if something went wrong
17f0f4a4	79	*/
667b6294	80	static int _get_more_prng_bytes(struct prng_context *ctx, int cont_test)
17f0f4a4 NH	81	{
	82	int i;
	83	unsigned char tmp[DEFAULT_BLK_SZ];
	84	unsigned char *output = NULL;
	85
	86
	87	dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",
	88	ctx);
	89
	90	hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ);
	91	hexdump("Input I: ", ctx->I, DEFAULT_BLK_SZ);
	92	hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);
	93
	94	/*
	95	* This algorithm is a 3 stage state machine
	96	*/
	97	for (i = 0; i < 3; i++) {
	98
	99	switch (i) {
	100	case 0:
	101	/*
	102	* Start by encrypting the counter value
	103	* This gives us an intermediate value I
	104	*/
	105	memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ);
	106	output = ctx->I;
	107	hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ);
	108	break;
	109	case 1:
	110
	111	/*
	112	* Next xor I with our secret vector V
	113	* encrypt that result to obtain our
	114	* pseudo random data which we output
	115	*/
	116	xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
	117	hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ);
	118	output = ctx->rand_data;
	119	break;
	120	case 2:
	121	/*
	122	* First check that we didn't produce the same
	123	* random data that we did last time around through this
	124	*/
	125	if (!memcmp(ctx->rand_data, ctx->last_rand_data,
	126	DEFAULT_BLK_SZ)) {
667b6294	127	if (cont_test) {
c5b1e545 NH	128	panic("cprng %p Failed repetition check!\n",
	129	ctx);
	130	}
	131
17f0f4a4 NH	132	printk(KERN_ERR
	133	"ctx %p Failed repetition check!\n",
	134	ctx);
c5b1e545	135
17f0f4a4 NH	136	ctx->flags \|= PRNG_NEED_RESET;
	137	return -EINVAL;
	138	}
	139	memcpy(ctx->last_rand_data, ctx->rand_data,
	140	DEFAULT_BLK_SZ);
	141
	142	/*
	143	* Lastly xor the random data with I
	144	* and encrypt that to obtain a new secret vector V
	145	*/
	146	xor_vectors(ctx->rand_data, ctx->I, tmp,
	147	DEFAULT_BLK_SZ);
	148	output = ctx->V;
	149	hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
	150	break;
	151	}
	152
	153
	154	/* do the encryption */
	155	crypto_cipher_encrypt_one(ctx->tfm, output, tmp);
	156
	157	}
	158
	159	/*
	160	* Now update our DT value
	161	*/
09fbf7c0	162	for (i = DEFAULT_BLK_SZ - 1; i >= 0; i--) {
17f0f4a4 NH	163	ctx->DT[i] += 1;
	164	if (ctx->DT[i] != 0)
	165	break;
	166	}
	167
	168	dbgprint("Returning new block for context %p\n", ctx);
	169	ctx->rand_data_valid = 0;
	170
	171	hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
	172	hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ);
	173	hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
	174	hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);
	175
	176	return 0;
	177	}
	178
	179	/* Our exported functions */
667b6294 NH	180	static int get_prng_bytes(char buf, size_t nbytes, struct prng_context ctx,
667b6294 NH	181	int do_cont_test)
17f0f4a4	182	{
17f0f4a4 NH	183	unsigned char *ptr = buf;
	184	unsigned int byte_count = (unsigned int)nbytes;
	185	int err;
	186
	187
ed940700	188	spin_lock_bh(&ctx->prng_lock);
17f0f4a4 NH	189
	190	err = -EINVAL;
	191	if (ctx->flags & PRNG_NEED_RESET)
	192	goto done;
	193
	194	/*
	195	* If the FIXED_SIZE flag is on, only return whole blocks of
	196	* pseudo random data
	197	*/
	198	err = -EINVAL;
	199	if (ctx->flags & PRNG_FIXED_SIZE) {
	200	if (nbytes < DEFAULT_BLK_SZ)
	201	goto done;
	202	byte_count = DEFAULT_BLK_SZ;
	203	}
	204
cde001e4 SM	205	/*
	206	* Return 0 in case of success as mandated by the kernel
	207	* crypto API interface definition.
	208	*/
	209	err = 0;
17f0f4a4 NH	210
	211	dbgprint(KERN_CRIT "getting %d random bytes for context %p\n",
	212	byte_count, ctx);
	213
	214
	215	remainder:
	216	if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
667b6294	217	if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
17f0f4a4 NH	218	memset(buf, 0, nbytes);
	219	err = -EINVAL;
	220	goto done;
	221	}
	222	}
	223
	224	/*
aa1a85db	225	* Copy any data less than an entire block
17f0f4a4 NH	226	*/
17f0f4a4 NH	227	if (byte_count < DEFAULT_BLK_SZ) {
aa1a85db	228	empty_rbuf:
714b33d1	229	while (ctx->rand_data_valid < DEFAULT_BLK_SZ) {
17f0f4a4 NH	230	*ptr = ctx->rand_data[ctx->rand_data_valid];
	231	ptr++;
	232	byte_count--;
714b33d1	233	ctx->rand_data_valid++;
17f0f4a4 NH	234	if (byte_count == 0)
	235	goto done;
	236	}
	237	}
	238
	239	/*
	240	* Now copy whole blocks
	241	*/
	242	for (; byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
aa1a85db	243	if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
667b6294	244	if (_get_more_prng_bytes(ctx, do_cont_test) < 0) {
aa1a85db JW	245	memset(buf, 0, nbytes);
	246	err = -EINVAL;
	247	goto done;
	248	}
17f0f4a4	249	}
aa1a85db JW	250	if (ctx->rand_data_valid > 0)
aa1a85db JW	251	goto empty_rbuf;
17f0f4a4 NH	252	memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
	253	ctx->rand_data_valid += DEFAULT_BLK_SZ;
	254	ptr += DEFAULT_BLK_SZ;
	255	}
	256
	257	/*
aa1a85db	258	* Now go back and get any remaining partial block
17f0f4a4 NH	259	*/
	260	if (byte_count)
	261	goto remainder;
	262
	263	done:
ed940700	264	spin_unlock_bh(&ctx->prng_lock);
17f0f4a4 NH	265	dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",
	266	err, ctx);
	267	return err;
	268	}
	269
	270	static void free_prng_context(struct prng_context *ctx)
	271	{
	272	crypto_free_cipher(ctx->tfm);
	273	}
	274
	275	static int reset_prng_context(struct prng_context *ctx,
e7c2422a HX	276	const unsigned char *key, size_t klen,
e7c2422a HX	277	const unsigned char V, const unsigned char DT)
17f0f4a4 NH	278	{
17f0f4a4 NH	279	int ret;
e7c2422a	280	const unsigned char *prng_key;
17f0f4a4	281
ed940700	282	spin_lock_bh(&ctx->prng_lock);
17f0f4a4 NH	283	ctx->flags \|= PRNG_NEED_RESET;
	284
	285	prng_key = (key != NULL) ? key : (unsigned char *)DEFAULT_PRNG_KEY;
	286
	287	if (!key)
	288	klen = DEFAULT_PRNG_KSZ;
	289
	290	if (V)
	291	memcpy(ctx->V, V, DEFAULT_BLK_SZ);
	292	else
	293	memcpy(ctx->V, DEFAULT_V_SEED, DEFAULT_BLK_SZ);
	294
	295	if (DT)
	296	memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
	297	else
	298	memset(ctx->DT, 0, DEFAULT_BLK_SZ);
	299
	300	memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
	301	memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ);
	302
17f0f4a4 NH	303	ctx->rand_data_valid = DEFAULT_BLK_SZ;
	304
	305	ret = crypto_cipher_setkey(ctx->tfm, prng_key, klen);
	306	if (ret) {
	307	dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
	308	crypto_cipher_get_flags(ctx->tfm));
17f0f4a4 NH	309	goto out;
	310	}
	311
fd09d7fa	312	ret = 0;
17f0f4a4 NH	313	ctx->flags &= ~PRNG_NEED_RESET;
17f0f4a4 NH	314	out:
ed940700	315	spin_unlock_bh(&ctx->prng_lock);
fd09d7fa	316	return ret;
17f0f4a4 NH	317	}
	318
	319	static int cprng_init(struct crypto_tfm *tfm)
	320	{
	321	struct prng_context *ctx = crypto_tfm_ctx(tfm);
	322
	323	spin_lock_init(&ctx->prng_lock);
fd09d7fa SAS	324	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
	325	if (IS_ERR(ctx->tfm)) {
	326	dbgprint(KERN_CRIT "Failed to alloc tfm for context %p\n",
	327	ctx);
	328	return PTR_ERR(ctx->tfm);
	329	}
17f0f4a4	330
d7992f42 NH	331	if (reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL) < 0)
	332	return -EINVAL;
	333
	334	/*
	335	* after allocation, we should always force the user to reset
	336	* so they don't inadvertently use the insecure default values
	337	* without specifying them intentially
	338	*/
	339	ctx->flags \|= PRNG_NEED_RESET;
	340	return 0;
17f0f4a4 NH	341	}
	342
	343	static void cprng_exit(struct crypto_tfm *tfm)
	344	{
	345	free_prng_context(crypto_tfm_ctx(tfm));
	346	}
	347
e7c2422a HX	348	static int cprng_get_random(struct crypto_rng *tfm,
	349	const u8 *src, unsigned int slen,
	350	u8 *rdata, unsigned int dlen)
17f0f4a4 NH	351	{
	352	struct prng_context *prng = crypto_rng_ctx(tfm);
	353
667b6294 NH	354	return get_prng_bytes(rdata, dlen, prng, 0);
	355	}
	356
2566578a NH	357	/*
	358	* This is the cprng_registered reset method the seed value is
	359	* interpreted as the tuple { V KEY DT}
	360	* V and KEY are required during reset, and DT is optional, detected
	361	* as being present by testing the length of the seed
	362	*/
e7c2422a HX	363	static int cprng_reset(struct crypto_rng *tfm,
e7c2422a HX	364	const u8 *seed, unsigned int slen)
17f0f4a4 NH	365	{
17f0f4a4 NH	366	struct prng_context *prng = crypto_rng_ctx(tfm);
e7c2422a HX	367	const u8 *key = seed + DEFAULT_BLK_SZ;
e7c2422a HX	368	const u8 *dt = NULL;
17f0f4a4 NH	369
	370	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
	371	return -EINVAL;
	372
2566578a NH	373	if (slen >= (2 * DEFAULT_BLK_SZ + DEFAULT_PRNG_KSZ))
	374	dt = key + DEFAULT_PRNG_KSZ;
	375
	376	reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, dt);
17f0f4a4 NH	377
	378	if (prng->flags & PRNG_NEED_RESET)
	379	return -EINVAL;
	380	return 0;
	381	}
	382
667b6294	383	#ifdef CONFIG_CRYPTO_FIPS
e7c2422a HX	384	static int fips_cprng_get_random(struct crypto_rng *tfm,
	385	const u8 *src, unsigned int slen,
	386	u8 *rdata, unsigned int dlen)
2f32bfd8 JSR	387	{
	388	struct prng_context *prng = crypto_rng_ctx(tfm);
	389
	390	return get_prng_bytes(rdata, dlen, prng, 1);
	391	}
	392
e7c2422a HX	393	static int fips_cprng_reset(struct crypto_rng *tfm,
e7c2422a HX	394	const u8 *seed, unsigned int slen)
2f32bfd8 JSR	395	{
2f32bfd8 JSR	396	u8 rdata[DEFAULT_BLK_SZ];
e7c2422a	397	const u8 *key = seed + DEFAULT_BLK_SZ;
2f32bfd8 JSR	398	int rc;
	399
	400	struct prng_context *prng = crypto_rng_ctx(tfm);
	401
505172e1 JW	402	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
	403	return -EINVAL;
	404
	405	/* fips strictly requires seed != key */
	406	if (!memcmp(seed, key, DEFAULT_PRNG_KSZ))
	407	return -EINVAL;
	408
2f32bfd8 JSR	409	rc = cprng_reset(tfm, seed, slen);
	410
	411	if (!rc)
	412	goto out;
	413
	414	/* this primes our continuity test */
	415	rc = get_prng_bytes(rdata, DEFAULT_BLK_SZ, prng, 0);
	416	prng->rand_data_valid = DEFAULT_BLK_SZ;
	417
	418	out:
	419	return rc;
	420	}
8fc229a5	421	#endif
2f32bfd8	422
e7c2422a HX	423	static struct rng_alg rng_algs[] = { {
	424	.generate = cprng_get_random,
	425	.seed = cprng_reset,
	426	.seedsize = DEFAULT_PRNG_KSZ + 2 * DEFAULT_BLK_SZ,
	427	.base = {
	428	.cra_name = "stdrng",
	429	.cra_driver_name = "ansi_cprng",
	430	.cra_priority = 100,
	431	.cra_ctxsize = sizeof(struct prng_context),
	432	.cra_module = THIS_MODULE,
	433	.cra_init = cprng_init,
	434	.cra_exit = cprng_exit,
8fc229a5 JK	435	}
	436	#ifdef CONFIG_CRYPTO_FIPS
	437	}, {
e7c2422a HX	438	.generate = fips_cprng_get_random,
	439	.seed = fips_cprng_reset,
	440	.seedsize = DEFAULT_PRNG_KSZ + 2 * DEFAULT_BLK_SZ,
	441	.base = {
	442	.cra_name = "fips(ansi_cprng)",
	443	.cra_driver_name = "fips_ansi_cprng",
	444	.cra_priority = 300,
	445	.cra_ctxsize = sizeof(struct prng_context),
	446	.cra_module = THIS_MODULE,
	447	.cra_init = cprng_init,
	448	.cra_exit = cprng_exit,
667b6294	449	}
667b6294	450	#endif
8fc229a5	451	} };
17f0f4a4 NH	452
	453	/* Module initalization */
	454	static int __init prng_mod_init(void)
	455	{
e7c2422a	456	return crypto_register_rngs(rng_algs, ARRAY_SIZE(rng_algs));
17f0f4a4 NH	457	}
	458
	459	static void __exit prng_mod_fini(void)
	460	{
e7c2422a	461	crypto_unregister_rngs(rng_algs, ARRAY_SIZE(rng_algs));
17f0f4a4 NH	462	}
	463
	464	MODULE_LICENSE("GPL");
	465	MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
	466	MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
	467	module_param(dbg, int, 0);
	468	MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
c4741b23	469	subsys_initcall(prng_mod_init);
17f0f4a4	470	module_exit(prng_mod_fini);
5d26a105	471	MODULE_ALIAS_CRYPTO("stdrng");
3e14dcf7	472	MODULE_ALIAS_CRYPTO("ansi_cprng");