drbg.h

  1/*
  2 * DRBG based on NIST SP800-90A
  3 *
  4 * Copyright Stephan Mueller <smueller@chronox.de>, 2014
  5 *
  6 * Redistribution and use in source and binary forms, with or without
  7 * modification, are permitted provided that the following conditions
  8 * are met:
  9 * 1. Redistributions of source code must retain the above copyright
 10 *    notice, and the entire permission notice in its entirety,
 11 *    including the disclaimer of warranties.
 12 * 2. Redistributions in binary form must reproduce the above copyright
 13 *    notice, this list of conditions and the following disclaimer in the
 14 *    documentation and/or other materials provided with the distribution.
 15 * 3. The name of the author may not be used to endorse or promote
 16 *    products derived from this software without specific prior
 17 *    written permission.
 18 *
 19 * ALTERNATIVELY, this product may be distributed under the terms of
 20 * the GNU General Public License, in which case the provisions of the GPL are
 21 * required INSTEAD OF the above restrictions.  (This clause is
 22 * necessary due to a potential bad interaction between the GPL and
 23 * the restrictions contained in a BSD-style copyright.)
 24 *
 25 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 26 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
 28 * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
 29 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 31 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 32 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 33 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 35 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
 36 * DAMAGE.
 37 */
 38
 39#ifndef _DRBG_H
 40#define _DRBG_H
 41
 42
 43#include <linux/random.h>
 44#include <linux/scatterlist.h>
 45#include <crypto/hash.h>
 46#include <crypto/skcipher.h>
 47#include <linux/module.h>
 48#include <linux/crypto.h>
 49#include <linux/slab.h>
 50#include <crypto/internal/drbg.h>
 51#include <crypto/internal/rng.h>
 52#include <crypto/rng.h>
 53#include <linux/fips.h>
 54#include <linux/mutex.h>
 55#include <linux/list.h>
 56#include <linux/workqueue.h>
 57
 58struct drbg_state;
 59typedef uint32_t drbg_flag_t;
 60
 61struct drbg_core {
 62	drbg_flag_t flags;	/* flags for the cipher */
 63	__u8 statelen;		/* maximum state length */
 64	__u8 blocklen_bytes;	/* block size of output in bytes */
 65	char cra_name[CRYPTO_MAX_ALG_NAME]; /* mapping to kernel crypto API */
 66	 /* kernel crypto API backend cipher name */
 67	char backend_cra_name[CRYPTO_MAX_ALG_NAME];
 68};
 69
 70struct drbg_state_ops {
 71	int (*update)(struct drbg_state *drbg, struct list_head *seed,
 72		      int reseed);
 73	int (*generate)(struct drbg_state *drbg,
 74			unsigned char *buf, unsigned int buflen,
 75			struct list_head *addtl);
 76	int (*crypto_init)(struct drbg_state *drbg);
 77	int (*crypto_fini)(struct drbg_state *drbg);
 78
 79};
 80
 81struct drbg_test_data {
 82	struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
 83};
 84
 85enum drbg_seed_state {
 86	DRBG_SEED_STATE_UNSEEDED,
 87	DRBG_SEED_STATE_PARTIAL, /* Seeded with !rng_is_initialized() */
 88	DRBG_SEED_STATE_FULL,
 89};
 90
 91struct drbg_state {
 92	struct mutex drbg_mutex;	/* lock around DRBG */
 93	unsigned char *V;	/* internal state 10.1.1.1 1a) */
 94	unsigned char *Vbuf;
 95	/* hash: static value 10.1.1.1 1b) hmac / ctr: key */
 96	unsigned char *C;
 97	unsigned char *Cbuf;
 98	/* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
 99	size_t reseed_ctr;
100	size_t reseed_threshold;
101	 /* some memory the DRBG can use for its operation */
102	unsigned char *scratchpad;
103	unsigned char *scratchpadbuf;
104	void *priv_data;	/* Cipher handle */
105
106	struct crypto_skcipher *ctr_handle;	/* CTR mode cipher handle */
107	struct skcipher_request *ctr_req;	/* CTR mode request handle */
108	__u8 *outscratchpadbuf;			/* CTR mode output scratchpad */
109        __u8 *outscratchpad;			/* CTR mode aligned outbuf */
110	struct crypto_wait ctr_wait;		/* CTR mode async wait obj */
111	struct scatterlist sg_in, sg_out;	/* CTR mode SGLs */
112
113	enum drbg_seed_state seeded;		/* DRBG fully seeded? */
114	unsigned long last_seed_time;
115	bool pr;		/* Prediction resistance enabled? */
116	bool fips_primed;	/* Continuous test primed? */
117	unsigned char *prev;	/* FIPS 140-2 continuous test value */
118	struct crypto_rng *jent;
119	const struct drbg_state_ops *d_ops;
120	const struct drbg_core *core;
121	struct drbg_string test_data;
122};
123
124static inline __u8 drbg_statelen(struct drbg_state *drbg)
125{
126	if (drbg && drbg->core)
127		return drbg->core->statelen;
128	return 0;
129}
130
131static inline __u8 drbg_blocklen(struct drbg_state *drbg)
132{
133	if (drbg && drbg->core)
134		return drbg->core->blocklen_bytes;
135	return 0;
136}
137
138static inline __u8 drbg_keylen(struct drbg_state *drbg)
139{
140	if (drbg && drbg->core)
141		return (drbg->core->statelen - drbg->core->blocklen_bytes);
142	return 0;
143}
144
145static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
146{
147	/* SP800-90A requires the limit 2**19 bits, but we return bytes */
148	return (1 << 16);
149}
150
151static inline size_t drbg_max_addtl(struct drbg_state *drbg)
152{
153	/* SP800-90A requires 2**35 bytes additional info str / pers str */
154#if (__BITS_PER_LONG == 32)
155	/*
156	 * SP800-90A allows smaller maximum numbers to be returned -- we
157	 * return SIZE_MAX - 1 to allow the verification of the enforcement
158	 * of this value in drbg_healthcheck_sanity.
159	 */
160	return (SIZE_MAX - 1);
161#else
162	return (1UL<<35);
163#endif
164}
165
166static inline size_t drbg_max_requests(struct drbg_state *drbg)
167{
168	/* SP800-90A requires 2**48 maximum requests before reseeding */
169	return (1<<20);
170}
171
172/*
173 * This is a wrapper to the kernel crypto API function of
174 * crypto_rng_generate() to allow the caller to provide additional data.
175 *
176 * @drng DRBG handle -- see crypto_rng_get_bytes
177 * @outbuf output buffer -- see crypto_rng_get_bytes
178 * @outlen length of output buffer -- see crypto_rng_get_bytes
179 * @addtl_input additional information string input buffer
180 * @addtllen length of additional information string buffer
181 *
182 * return
183 *	see crypto_rng_get_bytes
184 */
185static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
186			unsigned char *outbuf, unsigned int outlen,
187			struct drbg_string *addtl)
188{
189	return crypto_rng_generate(drng, addtl->buf, addtl->len,
190				   outbuf, outlen);
191}
192
193/*
194 * TEST code
195 *
196 * This is a wrapper to the kernel crypto API function of
197 * crypto_rng_generate() to allow the caller to provide additional data and
198 * allow furnishing of test_data
199 *
200 * @drng DRBG handle -- see crypto_rng_get_bytes
201 * @outbuf output buffer -- see crypto_rng_get_bytes
202 * @outlen length of output buffer -- see crypto_rng_get_bytes
203 * @addtl_input additional information string input buffer
204 * @addtllen length of additional information string buffer
205 * @test_data filled test data
206 *
207 * return
208 *	see crypto_rng_get_bytes
209 */
210static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
211			unsigned char *outbuf, unsigned int outlen,
212			struct drbg_string *addtl,
213			struct drbg_test_data *test_data)
214{
215	crypto_rng_set_entropy(drng, test_data->testentropy->buf,
216			       test_data->testentropy->len);
217	return crypto_rng_generate(drng, addtl->buf, addtl->len,
218				   outbuf, outlen);
219}
220
221/*
222 * TEST code
223 *
224 * This is a wrapper to the kernel crypto API function of
225 * crypto_rng_reset() to allow the caller to provide test_data
226 *
227 * @drng DRBG handle -- see crypto_rng_reset
228 * @pers personalization string input buffer
229 * @perslen length of additional information string buffer
230 * @test_data filled test data
231 *
232 * return
233 *	see crypto_rng_reset
234 */
235static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
236					 struct drbg_string *pers,
237					 struct drbg_test_data *test_data)
238{
239	crypto_rng_set_entropy(drng, test_data->testentropy->buf,
240			       test_data->testentropy->len);
241	return crypto_rng_reset(drng, pers->buf, pers->len);
242}
243
244/* DRBG type flags */
245#define DRBG_CTR	((drbg_flag_t)1<<0)
246#define DRBG_HMAC	((drbg_flag_t)1<<1)
247#define DRBG_HASH	((drbg_flag_t)1<<2)
248#define DRBG_TYPE_MASK	(DRBG_CTR | DRBG_HMAC | DRBG_HASH)
249/* DRBG strength flags */
250#define DRBG_STRENGTH128	((drbg_flag_t)1<<3)
251#define DRBG_STRENGTH192	((drbg_flag_t)1<<4)
252#define DRBG_STRENGTH256	((drbg_flag_t)1<<5)
253#define DRBG_STRENGTH_MASK	(DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
254				 DRBG_STRENGTH256)
255
256enum drbg_prefixes {
257	DRBG_PREFIX0 = 0x00,
258	DRBG_PREFIX1,
259	DRBG_PREFIX2,
260	DRBG_PREFIX3
261};
262
263#endif /* _DRBG_H */