Commit 17f0f4a4 authored by Neil Horman's avatar Neil Horman Committed by Herbert Xu

crypto: rng - RNG interface and implementation

This patch adds a random number generator interface as well as a
cryptographic pseudo-random number generator based on AES.  It is
meant to be used in cases where a deterministic CPRNG is required.

One of the first applications will be as an input in the IPsec IV
generation process.
Signed-off-by: 's avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: 's avatarHerbert Xu <herbert@gondor.apana.org.au>
parent ccb778e1
......@@ -46,6 +46,10 @@ config CRYPTO_HASH
tristate
select CRYPTO_ALGAPI
config CRYPTO_RNG
tristate
select CRYPTO_ALGAPI
config CRYPTO_MANAGER
tristate "Cryptographic algorithm manager"
select CRYPTO_AEAD
......@@ -689,6 +693,18 @@ config CRYPTO_LZO
help
This is the LZO algorithm.
comment "Random Number Generation"
config CRYPTO_ANSI_CPRNG
tristate "Pseudo Random Number Generation for Cryptographic modules"
select CRYPTO_AES
select CRYPTO_RNG
select CRYPTO_FIPS
help
This option enables the generic pseudo random number generator
for cryptographic modules. Uses the Algorithm specified in
ANSI X9.31 A.2.4
source "drivers/crypto/Kconfig"
endif # if CRYPTO
......@@ -73,7 +73,9 @@ obj-$(CONFIG_CRYPTO_MICHAEL_MIC) += michael_mic.o
obj-$(CONFIG_CRYPTO_CRC32C) += crc32c.o
obj-$(CONFIG_CRYPTO_AUTHENC) += authenc.o
obj-$(CONFIG_CRYPTO_LZO) += lzo.o
obj-$(CONFIG_CRYPTO_RNG) += rng.o
obj-$(CONFIG_CRYPTO_RNG) += krng.o
obj-$(CONFIG_CRYPTO_ANSI_CPRNG) += ansi_cprng.o
obj-$(CONFIG_CRYPTO_TEST) += tcrypt.o
#
......
/*
* 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");
/*
* RNG implementation using standard kernel RNG.
*
* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
*
* 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/random.h>
static int krng_get_random(struct crypto_rng *tfm, u8 *rdata, unsigned int dlen)
{
get_random_bytes(rdata, dlen);
return 0;
}
static int krng_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
{
return 0;
}
static struct crypto_alg krng_alg = {
.cra_name = "stdrng",
.cra_driver_name = "krng",
.cra_priority = 200,
.cra_flags = CRYPTO_ALG_TYPE_RNG,
.cra_ctxsize = 0,
.cra_type = &crypto_rng_type,
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(krng_alg.cra_list),
.cra_u = {
.rng = {
.rng_make_random = krng_get_random,
.rng_reset = krng_reset,
.seedsize = 0,
}
}
};
/* Module initalization */
static int __init krng_mod_init(void)
{
return crypto_register_alg(&krng_alg);
}
static void __exit krng_mod_fini(void)
{
crypto_unregister_alg(&krng_alg);
return;
}
module_init(krng_mod_init);
module_exit(krng_mod_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Kernel Random Number Generator");
MODULE_ALIAS("stdrng");
/*
* Cryptographic API.
*
* RNG operations.
*
* Copyright (c) 2008 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 option)
* any later version.
*
*/
#include <asm/atomic.h>
#include <crypto/internal/rng.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/random.h>
#include <linux/seq_file.h>
#include <linux/string.h>
static DEFINE_MUTEX(crypto_default_rng_lock);
struct crypto_rng *crypto_default_rng;
EXPORT_SYMBOL_GPL(crypto_default_rng);
static int crypto_default_rng_refcnt;
static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
{
u8 *buf = NULL;
int err;
if (!seed && slen) {
buf = kmalloc(slen, GFP_KERNEL);
if (!buf)
return -ENOMEM;
get_random_bytes(buf, slen);
seed = buf;
}
err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);
kfree(buf);
return err;
}
static int crypto_init_rng_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
{
struct rng_alg *alg = &tfm->__crt_alg->cra_rng;
struct rng_tfm *ops = &tfm->crt_rng;
ops->rng_gen_random = alg->rng_make_random;
ops->rng_reset = rngapi_reset;
return 0;
}
static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
__attribute__ ((unused));
static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
{
seq_printf(m, "type : rng\n");
seq_printf(m, "seedsize : %u\n", alg->cra_rng.seedsize);
}
static unsigned int crypto_rng_ctxsize(struct crypto_alg *alg, u32 type,
u32 mask)
{
return alg->cra_ctxsize;
}
const struct crypto_type crypto_rng_type = {
.ctxsize = crypto_rng_ctxsize,
.init = crypto_init_rng_ops,
#ifdef CONFIG_PROC_FS
.show = crypto_rng_show,
#endif
};
EXPORT_SYMBOL_GPL(crypto_rng_type);
int crypto_get_default_rng(void)
{
struct crypto_rng *rng;
int err;
mutex_lock(&crypto_default_rng_lock);
if (!crypto_default_rng) {
rng = crypto_alloc_rng("stdrng", 0, 0);
err = PTR_ERR(rng);
if (IS_ERR(rng))
goto unlock;
err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
if (err) {
crypto_free_rng(rng);
goto unlock;
}
crypto_default_rng = rng;
}
crypto_default_rng_refcnt++;
err = 0;
unlock:
mutex_unlock(&crypto_default_rng_lock);
return err;
}
EXPORT_SYMBOL_GPL(crypto_get_default_rng);
void crypto_put_default_rng(void)
{
mutex_lock(&crypto_default_rng_lock);
if (!--crypto_default_rng_refcnt) {
crypto_free_rng(crypto_default_rng);
crypto_default_rng = NULL;
}
mutex_unlock(&crypto_default_rng_lock);
}
EXPORT_SYMBOL_GPL(crypto_put_default_rng);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Random Number Genertor");
/*
* RNG: Random Number Generator algorithms under the crypto API
*
* Copyright (c) 2008 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 option)
* any later version.
*
*/
#ifndef _CRYPTO_INTERNAL_RNG_H
#define _CRYPTO_INTERNAL_RNG_H
#include <crypto/algapi.h>
#include <crypto/rng.h>
extern const struct crypto_type crypto_rng_type;
static inline void *crypto_rng_ctx(struct crypto_rng *tfm)
{
return crypto_tfm_ctx(&tfm->base);
}
#endif
/*
* RNG: Random Number Generator algorithms under the crypto API
*
* Copyright (c) 2008 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 option)
* any later version.
*
*/
#ifndef _CRYPTO_RNG_H
#define _CRYPTO_RNG_H
#include <linux/crypto.h>
extern struct crypto_rng *crypto_default_rng;
int crypto_get_default_rng(void);
void crypto_put_default_rng(void);
static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm)
{
return (struct crypto_rng *)tfm;
}
static inline struct crypto_rng *crypto_alloc_rng(const char *alg_name,
u32 type, u32 mask)
{
type &= ~CRYPTO_ALG_TYPE_MASK;
type |= CRYPTO_ALG_TYPE_RNG;
mask |= CRYPTO_ALG_TYPE_MASK;
return __crypto_rng_cast(crypto_alloc_base(alg_name, type, mask));
}
static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)
{
return &tfm->base;
}
static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
{
return &crypto_rng_tfm(tfm)->__crt_alg->cra_rng;
}
static inline struct rng_tfm *crypto_rng_crt(struct crypto_rng *tfm)
{
return &crypto_rng_tfm(tfm)->crt_rng;
}
static inline void crypto_free_rng(struct crypto_rng *tfm)
{
crypto_free_tfm(crypto_rng_tfm(tfm));
}
static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
u8 *rdata, unsigned int dlen)
{
return crypto_rng_crt(tfm)->rng_gen_random(tfm, rdata, dlen);
}
static inline int crypto_rng_reset(struct crypto_rng *tfm,
u8 *seed, unsigned int slen)
{
return crypto_rng_crt(tfm)->rng_reset(tfm, seed, slen);
}
static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
{
return crypto_rng_alg(tfm)->seedsize;
}
#endif