/*
* DRBG based on NIST SP800-90A
*
* Copyright Stephan Mueller <[email protected]>, 2014
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU General Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
#ifndef _DRBG_H
#define _DRBG_H
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <crypto/hash.h>
#include <crypto/skcipher.h>
#include <linux/module.h>
#include <linux/crypto.h>
#include <linux/slab.h>
#include <crypto/internal/rng.h>
#include <crypto/rng.h>
#include <linux/fips.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/workqueue.h>
/*
* Concatenation Helper and string operation helper
*
* SP800-90A requires the concatenation of different data. To avoid copying
* buffers around or allocate additional memory, the following data structure
* is used to point to the original memory with its size. In addition, it
* is used to build a linked list. The linked list defines the concatenation
* of individual buffers. The order of memory block referenced in that
* linked list determines the order of concatenation.
*/
struct drbg_string {
const unsigned char *buf;
size_t len;
struct list_head list;
};
static inline void drbg_string_fill(struct drbg_string *string,
const unsigned char *buf, size_t len)
{
string->buf = buf;
string->len = len;
INIT_LIST_HEAD(&string->list);
}
struct drbg_state;
typedef uint32_t drbg_flag_t;
struct drbg_core {
drbg_flag_t flags; /* flags for the cipher */
__u8 statelen; /* maximum state length */
__u8 blocklen_bytes; /* block size of output in bytes */
char cra_name[CRYPTO_MAX_ALG_NAME]; /* mapping to kernel crypto API */
/* kernel crypto API backend cipher name */
char backend_cra_name[CRYPTO_MAX_ALG_NAME];
};
struct drbg_state_ops {
int (*update)(struct drbg_state *drbg, struct list_head *seed,
int reseed);
int (*generate)(struct drbg_state *drbg,
unsigned char *buf, unsigned int buflen,
struct list_head *addtl);
int (*crypto_init)(struct drbg_state *drbg);
int (*crypto_fini)(struct drbg_state *drbg);
};
struct drbg_test_data {
struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
};
enum drbg_seed_state {
DRBG_SEED_STATE_UNSEEDED,
DRBG_SEED_STATE_PARTIAL, /* Seeded with !rng_is_initialized() */
DRBG_SEED_STATE_FULL,
};
struct drbg_state {
struct mutex drbg_mutex; /* lock around DRBG */
unsigned char *V; /* internal state 10.1.1.1 1a) */
unsigned char *Vbuf;
/* hash: static value 10.1.1.1 1b) hmac / ctr: key */
unsigned char *C;
unsigned char *Cbuf;
/* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
size_t reseed_ctr;
size_t reseed_threshold;
/* some memory the DRBG can use for its operation */
unsigned char *scratchpad;
unsigned char *scratchpadbuf;
void *priv_data; /* Cipher handle */
struct crypto_skcipher *ctr_handle; /* CTR mode cipher handle */
struct skcipher_request *ctr_req; /* CTR mode request handle */
__u8 *outscratchpadbuf; /* CTR mode output scratchpad */
__u8 *outscratchpad; /* CTR mode aligned outbuf */
struct crypto_wait ctr_wait; /* CTR mode async wait obj */
struct scatterlist sg_in, sg_out; /* CTR mode SGLs */
enum drbg_seed_state seeded; /* DRBG fully seeded? */
unsigned long last_seed_time;
bool pr; /* Prediction resistance enabled? */
bool fips_primed; /* Continuous test primed? */
unsigned char *prev; /* FIPS 140-2 continuous test value */
struct crypto_rng *jent;
const struct drbg_state_ops *d_ops;
const struct drbg_core *core;
struct drbg_string test_data;
};
static inline __u8 drbg_statelen(struct drbg_state *drbg)
{
if (drbg && drbg->core)
return drbg->core->statelen;
return 0;
}
static inline __u8 drbg_blocklen(struct drbg_state *drbg)
{
if (drbg && drbg->core)
return drbg->core->blocklen_bytes;
return 0;
}
static inline __u8 drbg_keylen(struct drbg_state *drbg)
{
if (drbg && drbg->core)
return (drbg->core->statelen - drbg->core->blocklen_bytes);
return 0;
}
static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
{
/* SP800-90A requires the limit 2**19 bits, but we return bytes */
return (1 << 16);
}
static inline size_t drbg_max_addtl(struct drbg_state *drbg)
{
/* SP800-90A requires 2**35 bytes additional info str / pers str */
#if (__BITS_PER_LONG == 32)
/*
* SP800-90A allows smaller maximum numbers to be returned -- we
* return SIZE_MAX - 1 to allow the verification of the enforcement
* of this value in drbg_healthcheck_sanity.
*/
return (SIZE_MAX - 1);
#else
return (1UL<<35);
#endif
}
static inline size_t drbg_max_requests(struct drbg_state *drbg)
{
/* SP800-90A requires 2**48 maximum requests before reseeding */
return (1<<20);
}
/*
* This is a wrapper to the kernel crypto API function of
* crypto_rng_generate() to allow the caller to provide additional data.
*
* @drng DRBG handle -- see crypto_rng_get_bytes
* @outbuf output buffer -- see crypto_rng_get_bytes
* @outlen length of output buffer -- see crypto_rng_get_bytes
* @addtl_input additional information string input buffer
* @addtllen length of additional information string buffer
*
* return
* see crypto_rng_get_bytes
*/
static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
unsigned char *outbuf, unsigned int outlen,
struct drbg_string *addtl)
{
return crypto_rng_generate(drng, addtl->buf, addtl->len,
outbuf, outlen);
}
/*
* TEST code
*
* This is a wrapper to the kernel crypto API function of
* crypto_rng_generate() to allow the caller to provide additional data and
* allow furnishing of test_data
*
* @drng DRBG handle -- see crypto_rng_get_bytes
* @outbuf output buffer -- see crypto_rng_get_bytes
* @outlen length of output buffer -- see crypto_rng_get_bytes
* @addtl_input additional information string input buffer
* @addtllen length of additional information string buffer
* @test_data filled test data
*
* return
* see crypto_rng_get_bytes
*/
static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
unsigned char *outbuf, unsigned int outlen,
struct drbg_string *addtl,
struct drbg_test_data *test_data)
{
crypto_rng_set_entropy(drng, test_data->testentropy->buf,
test_data->testentropy->len);
return crypto_rng_generate(drng, addtl->buf, addtl->len,
outbuf, outlen);
}
/*
* TEST code
*
* This is a wrapper to the kernel crypto API function of
* crypto_rng_reset() to allow the caller to provide test_data
*
* @drng DRBG handle -- see crypto_rng_reset
* @pers personalization string input buffer
* @perslen length of additional information string buffer
* @test_data filled test data
*
* return
* see crypto_rng_reset
*/
static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
struct drbg_string *pers,
struct drbg_test_data *test_data)
{
crypto_rng_set_entropy(drng, test_data->testentropy->buf,
test_data->testentropy->len);
return crypto_rng_reset(drng, pers->buf, pers->len);
}
/* DRBG type flags */
#define DRBG_CTR ((drbg_flag_t)1<<0)
#define DRBG_HMAC ((drbg_flag_t)1<<1)
#define DRBG_HASH ((drbg_flag_t)1<<2)
#define DRBG_TYPE_MASK (DRBG_CTR | DRBG_HMAC | DRBG_HASH)
/* DRBG strength flags */
#define DRBG_STRENGTH128 ((drbg_flag_t)1<<3)
#define DRBG_STRENGTH192 ((drbg_flag_t)1<<4)
#define DRBG_STRENGTH256 ((drbg_flag_t)1<<5)
#define DRBG_STRENGTH_MASK (DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
DRBG_STRENGTH256)
enum drbg_prefixes {
DRBG_PREFIX0 = 0x00,
DRBG_PREFIX1,
DRBG_PREFIX2,
DRBG_PREFIX3
};
#endif /* _DRBG_H */
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