[linux-2.6-block.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>

#include "internal.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 succeded, <0 if something went wrong
 */
static int _get_more_prng_bytes(struct prng_context *ctx)
{
	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 (fips_enabled) {
					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)
{
	unsigned long flags;
	unsigned char *ptr = buf;
	unsigned int byte_count = (unsigned int)nbytes;
	int err;


	if (nbytes < 0)
		return -EINVAL;

	spin_lock_irqsave(&ctx->prng_lock, flags);

	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;
	}

	err = byte_count;

	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) < 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:
		for (; ctx->rand_data_valid < DEFAULT_BLK_SZ;
			ctx->rand_data_valid++) {
			*ptr = ctx->rand_data[ctx->rand_data_valid];
			ptr++;
			byte_count--;
			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) < 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_irqrestore(&ctx->prng_lock, flags);
	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,
			      unsigned char *key, size_t klen,
			      unsigned char *V, unsigned char *DT)
{
	int ret;
	int rc = -EINVAL;
	unsigned char *prng_key;

	spin_lock(&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);

	if (ctx->tfm)
		crypto_free_cipher(ctx->tfm);

	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);
		ctx->tfm = NULL;
		goto out;
	}

	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));
		crypto_free_cipher(ctx->tfm);
		goto out;
	}

	rc = 0;
	ctx->flags &= ~PRNG_NEED_RESET;
out:
	spin_unlock(&ctx->prng_lock);

	return rc;

}

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

	spin_lock_init(&ctx->prng_lock);

	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, u8 *rdata,
			    unsigned int dlen)
{
	struct prng_context *prng = crypto_rng_ctx(tfm);

	return get_prng_bytes(rdata, dlen, prng);
}

/*
 *  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, u8 *seed, unsigned int slen)
{
	struct prng_context *prng = crypto_rng_ctx(tfm);
	u8 *key = seed + DEFAULT_BLK_SZ;
	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;
}

static struct crypto_alg rng_alg = {
	.cra_name		= "stdrng",
	.cra_driver_name	= "ansi_cprng",
	.cra_priority		= 100,
	.cra_flags		= CRYPTO_ALG_TYPE_RNG,
	.cra_ctxsize		= sizeof(struct prng_context),
	.cra_type		= &crypto_rng_type,
	.cra_module		= THIS_MODULE,
	.cra_list		= LIST_HEAD_INIT(rng_alg.cra_list),
	.cra_init		= cprng_init,
	.cra_exit		= cprng_exit,
	.cra_u			= {
		.rng = {
			.rng_make_random	= cprng_get_random,
			.rng_reset		= cprng_reset,
			.seedsize = DEFAULT_PRNG_KSZ + 2*DEFAULT_BLK_SZ,
		}
	}
};


/* Module initalization */
static int __init prng_mod_init(void)
{
	int ret = 0;

	if (fips_enabled)
		rng_alg.cra_priority += 200;

	ret = crypto_register_alg(&rng_alg);

	if (ret)
		goto out;
out:
	return 0;
}

static void __exit prng_mod_fini(void)
{
	crypto_unregister_alg(&rng_alg);
	return;
}

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