[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)) {
				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 = 0; i < DEFAULT_BLK_SZ; 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 up to the next whole block size
	 */
	if (byte_count < DEFAULT_BLK_SZ) {
		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 (_get_more_prng_bytes(ctx) < 0) {
			memset(buf, 0, nbytes);
			err = -EINVAL;
			goto done;
		}
		memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
		ctx->rand_data_valid += DEFAULT_BLK_SZ;
		ptr += DEFAULT_BLK_SZ;
	}

	/*
	 * Now copy any extra partial data
	 */
	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);

	return reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL);
}

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);
}

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_PRNG_KSZ;

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

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

	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 + 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)) {
135	printk(KERN_ERR
136	"ctx %p Failed repetition check!\n",
137	ctx);
138	ctx->flags \|= PRNG_NEED_RESET;
139	return -EINVAL;
140	}
141	memcpy(ctx->last_rand_data, ctx->rand_data,
142	DEFAULT_BLK_SZ);
143
144	/*
145	* Lastly xor the random data with I
146	* and encrypt that to obtain a new secret vector V
147	*/
148	xor_vectors(ctx->rand_data, ctx->I, tmp,
149	DEFAULT_BLK_SZ);
150	output = ctx->V;
151	hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
152	break;
153	}
154
155
156	/* do the encryption */
157	crypto_cipher_encrypt_one(ctx->tfm, output, tmp);
158
159	}
160
161	/*
162	* Now update our DT value
163	*/
164	for (i = 0; i < DEFAULT_BLK_SZ; i++) {
165	ctx->DT[i] += 1;
166	if (ctx->DT[i] != 0)
167	break;
168	}
169
170	dbgprint("Returning new block for context %p\n", ctx);
171	ctx->rand_data_valid = 0;
172
173	hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
174	hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ);
175	hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
176	hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);
177
178	return 0;
179	}
180
181	/* Our exported functions */
182	static int get_prng_bytes(char buf, size_t nbytes, struct prng_context ctx)
183	{
184	unsigned long flags;
185	unsigned char *ptr = buf;
186	unsigned int byte_count = (unsigned int)nbytes;
187	int err;
188
189
190	if (nbytes < 0)
191	return -EINVAL;
192
193	spin_lock_irqsave(&ctx->prng_lock, flags);
194
195	err = -EINVAL;
196	if (ctx->flags & PRNG_NEED_RESET)
197	goto done;
198
199	/*
200	* If the FIXED_SIZE flag is on, only return whole blocks of
201	* pseudo random data
202	*/
203	err = -EINVAL;
204	if (ctx->flags & PRNG_FIXED_SIZE) {
205	if (nbytes < DEFAULT_BLK_SZ)
206	goto done;
207	byte_count = DEFAULT_BLK_SZ;
208	}
209
210	err = byte_count;
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) {
218	if (_get_more_prng_bytes(ctx) < 0) {
219	memset(buf, 0, nbytes);
220	err = -EINVAL;
221	goto done;
222	}
223	}
224
225	/*
226	* Copy up to the next whole block size
227	*/
228	if (byte_count < DEFAULT_BLK_SZ) {
229	for (; ctx->rand_data_valid < DEFAULT_BLK_SZ;
230	ctx->rand_data_valid++) {
231	*ptr = ctx->rand_data[ctx->rand_data_valid];
232	ptr++;
233	byte_count--;
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) {
243	if (_get_more_prng_bytes(ctx) < 0) {
244	memset(buf, 0, nbytes);
245	err = -EINVAL;
246	goto done;
247	}
248	memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
249	ctx->rand_data_valid += DEFAULT_BLK_SZ;
250	ptr += DEFAULT_BLK_SZ;
251	}
252
253	/*
254	* Now copy any extra partial data
255	*/
256	if (byte_count)
257	goto remainder;
258
259	done:
260	spin_unlock_irqrestore(&ctx->prng_lock, flags);
261	dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",
262	err, ctx);
263	return err;
264	}
265
266	static void free_prng_context(struct prng_context *ctx)
267	{
268	crypto_free_cipher(ctx->tfm);
269	}
270
271	static int reset_prng_context(struct prng_context *ctx,
272	unsigned char *key, size_t klen,
273	unsigned char V, unsigned char DT)
274	{
275	int ret;
276	int rc = -EINVAL;
277	unsigned char *prng_key;
278
279	spin_lock(&ctx->prng_lock);
280	ctx->flags \|= PRNG_NEED_RESET;
281
282	prng_key = (key != NULL) ? key : (unsigned char *)DEFAULT_PRNG_KEY;
283
284	if (!key)
285	klen = DEFAULT_PRNG_KSZ;
286
287	if (V)
288	memcpy(ctx->V, V, DEFAULT_BLK_SZ);
289	else
290	memcpy(ctx->V, DEFAULT_V_SEED, DEFAULT_BLK_SZ);
291
292	if (DT)
293	memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
294	else
295	memset(ctx->DT, 0, DEFAULT_BLK_SZ);
296
297	memset(ctx->rand_data, 0, DEFAULT_BLK_SZ);
298	memset(ctx->last_rand_data, 0, DEFAULT_BLK_SZ);
299
300	if (ctx->tfm)
301	crypto_free_cipher(ctx->tfm);
302
303	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
304	if (IS_ERR(ctx->tfm)) {
305	dbgprint(KERN_CRIT "Failed to alloc tfm for context %p\n",
306	ctx);
307	ctx->tfm = NULL;
308	goto out;
309	}
310
311	ctx->rand_data_valid = DEFAULT_BLK_SZ;
312
313	ret = crypto_cipher_setkey(ctx->tfm, prng_key, klen);
314	if (ret) {
315	dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
316	crypto_cipher_get_flags(ctx->tfm));
317	crypto_free_cipher(ctx->tfm);
318	goto out;
319	}
320
321	rc = 0;
322	ctx->flags &= ~PRNG_NEED_RESET;
323	out:
324	spin_unlock(&ctx->prng_lock);
325
326	return rc;
327
328	}
329
330	static int cprng_init(struct crypto_tfm *tfm)
331	{
332	struct prng_context *ctx = crypto_tfm_ctx(tfm);
333
334	spin_lock_init(&ctx->prng_lock);
335
336	return reset_prng_context(ctx, NULL, DEFAULT_PRNG_KSZ, NULL, NULL);
337	}
338
339	static void cprng_exit(struct crypto_tfm *tfm)
340	{
341	free_prng_context(crypto_tfm_ctx(tfm));
342	}
343
344	static int cprng_get_random(struct crypto_rng tfm, u8 rdata,
345	unsigned int dlen)
346	{
347	struct prng_context *prng = crypto_rng_ctx(tfm);
348
349	return get_prng_bytes(rdata, dlen, prng);
350	}
351
352	static int cprng_reset(struct crypto_rng tfm, u8 seed, unsigned int slen)
353	{
354	struct prng_context *prng = crypto_rng_ctx(tfm);
355	u8 *key = seed + DEFAULT_PRNG_KSZ;
356
357	if (slen < DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ)
358	return -EINVAL;
359
360	reset_prng_context(prng, key, DEFAULT_PRNG_KSZ, seed, NULL);
361
362	if (prng->flags & PRNG_NEED_RESET)
363	return -EINVAL;
364	return 0;
365	}
366
367	static struct crypto_alg rng_alg = {
368	.cra_name = "stdrng",
369	.cra_driver_name = "ansi_cprng",
370	.cra_priority = 100,
371	.cra_flags = CRYPTO_ALG_TYPE_RNG,
372	.cra_ctxsize = sizeof(struct prng_context),
373	.cra_type = &crypto_rng_type,
374	.cra_module = THIS_MODULE,
375	.cra_list = LIST_HEAD_INIT(rng_alg.cra_list),
376	.cra_init = cprng_init,
377	.cra_exit = cprng_exit,
378	.cra_u = {
379	.rng = {
380	.rng_make_random = cprng_get_random,
381	.rng_reset = cprng_reset,
382	.seedsize = DEFAULT_PRNG_KSZ + DEFAULT_BLK_SZ,
383	}
384	}
385	};
386
387
388	/* Module initalization */
389	static int __init prng_mod_init(void)
390	{
391	int ret = 0;
392
393	if (fips_enabled)
394	rng_alg.cra_priority += 200;
395
396	ret = crypto_register_alg(&rng_alg);
397
398	if (ret)
399	goto out;
400	out:
401	return 0;
402	}
403
404	static void __exit prng_mod_fini(void)
405	{
406	crypto_unregister_alg(&rng_alg);
407	return;
408	}
409
410	MODULE_LICENSE("GPL");
411	MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
412	MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
413	module_param(dbg, int, 0);
414	MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
415	module_init(prng_mod_init);
416	module_exit(prng_mod_fini);
417	MODULE_ALIAS("stdrng");