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/rng.h>
51#include <crypto/rng.h>
52#include <linux/fips.h>
53#include <linux/mutex.h>
54#include <linux/list.h>
55#include <linux/workqueue.h>
56
57/*
58 * Concatenation Helper and string operation helper
59 *
60 * SP800-90A requires the concatenation of different data. To avoid copying
61 * buffers around or allocate additional memory, the following data structure
62 * is used to point to the original memory with its size. In addition, it
63 * is used to build a linked list. The linked list defines the concatenation
64 * of individual buffers. The order of memory block referenced in that
65 * linked list determines the order of concatenation.
66 */
67struct drbg_string {
68	const unsigned char *buf;
69	size_t len;
70	struct list_head list;
71};
72
73static inline void drbg_string_fill(struct drbg_string *string,
74				    const unsigned char *buf, size_t len)
75{
76	string->buf = buf;
77	string->len = len;
78	INIT_LIST_HEAD(&string->list);
79}
80
81struct drbg_state;
82typedef uint32_t drbg_flag_t;
83
84struct drbg_core {
85	drbg_flag_t flags;	/* flags for the cipher */
86	__u8 statelen;		/* maximum state length */
87	__u8 blocklen_bytes;	/* block size of output in bytes */
88	char cra_name[CRYPTO_MAX_ALG_NAME]; /* mapping to kernel crypto API */
89	 /* kernel crypto API backend cipher name */
90	char backend_cra_name[CRYPTO_MAX_ALG_NAME];
91};
92
93struct drbg_state_ops {
94	int (*update)(struct drbg_state *drbg, struct list_head *seed,
95		      int reseed);
96	int (*generate)(struct drbg_state *drbg,
97			unsigned char *buf, unsigned int buflen,
98			struct list_head *addtl);
99	int (*crypto_init)(struct drbg_state *drbg);
100	int (*crypto_fini)(struct drbg_state *drbg);
101
102};
103
104struct drbg_test_data {
105	struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
106};
107
108enum drbg_seed_state {
109	DRBG_SEED_STATE_UNSEEDED,
110	DRBG_SEED_STATE_PARTIAL, /* Seeded with !rng_is_initialized() */
111	DRBG_SEED_STATE_FULL,
112};
113
114struct drbg_state {
115	struct mutex drbg_mutex;	/* lock around DRBG */
116	unsigned char *V;	/* internal state 10.1.1.1 1a) */
117	unsigned char *Vbuf;
118	/* hash: static value 10.1.1.1 1b) hmac / ctr: key */
119	unsigned char *C;
120	unsigned char *Cbuf;
121	/* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
122	size_t reseed_ctr;
123	size_t reseed_threshold;
124	 /* some memory the DRBG can use for its operation */
125	unsigned char *scratchpad;
126	unsigned char *scratchpadbuf;
127	void *priv_data;	/* Cipher handle */
128
129	struct crypto_skcipher *ctr_handle;	/* CTR mode cipher handle */
130	struct skcipher_request *ctr_req;	/* CTR mode request handle */
131	__u8 *outscratchpadbuf;			/* CTR mode output scratchpad */
132        __u8 *outscratchpad;			/* CTR mode aligned outbuf */
133	struct crypto_wait ctr_wait;		/* CTR mode async wait obj */
134	struct scatterlist sg_in, sg_out;	/* CTR mode SGLs */
135
136	enum drbg_seed_state seeded;		/* DRBG fully seeded? */
137	unsigned long last_seed_time;
138	bool pr;		/* Prediction resistance enabled? */
139	bool fips_primed;	/* Continuous test primed? */
140	unsigned char *prev;	/* FIPS 140-2 continuous test value */
141	struct crypto_rng *jent;
142	const struct drbg_state_ops *d_ops;
143	const struct drbg_core *core;
144	struct drbg_string test_data;
145};
146
147static inline __u8 drbg_statelen(struct drbg_state *drbg)
148{
149	if (drbg && drbg->core)
150		return drbg->core->statelen;
151	return 0;
152}
153
154static inline __u8 drbg_blocklen(struct drbg_state *drbg)
155{
156	if (drbg && drbg->core)
157		return drbg->core->blocklen_bytes;
158	return 0;
159}
160
161static inline __u8 drbg_keylen(struct drbg_state *drbg)
162{
163	if (drbg && drbg->core)
164		return (drbg->core->statelen - drbg->core->blocklen_bytes);
165	return 0;
166}
167
168static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
169{
170	/* SP800-90A requires the limit 2**19 bits, but we return bytes */
171	return (1 << 16);
172}
173
174static inline size_t drbg_max_addtl(struct drbg_state *drbg)
175{
176	/* SP800-90A requires 2**35 bytes additional info str / pers str */
177#if (__BITS_PER_LONG == 32)
178	/*
179	 * SP800-90A allows smaller maximum numbers to be returned -- we
180	 * return SIZE_MAX - 1 to allow the verification of the enforcement
181	 * of this value in drbg_healthcheck_sanity.
182	 */
183	return (SIZE_MAX - 1);
184#else
185	return (1UL<<35);
186#endif
187}
188
189static inline size_t drbg_max_requests(struct drbg_state *drbg)
190{
191	/* SP800-90A requires 2**48 maximum requests before reseeding */
192	return (1<<20);
193}
194
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.
198 *
199 * @drng DRBG handle -- see crypto_rng_get_bytes
200 * @outbuf output buffer -- see crypto_rng_get_bytes
201 * @outlen length of output buffer -- see crypto_rng_get_bytes
202 * @addtl_input additional information string input buffer
203 * @addtllen length of additional information string buffer
204 *
205 * return
206 *	see crypto_rng_get_bytes
207 */
208static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
209			unsigned char *outbuf, unsigned int outlen,
210			struct drbg_string *addtl)
211{
212	return crypto_rng_generate(drng, addtl->buf, addtl->len,
213				   outbuf, outlen);
214}
215
216/*
217 * TEST code
218 *
219 * This is a wrapper to the kernel crypto API function of
220 * crypto_rng_generate() to allow the caller to provide additional data and
221 * allow furnishing of test_data
222 *
223 * @drng DRBG handle -- see crypto_rng_get_bytes
224 * @outbuf output buffer -- see crypto_rng_get_bytes
225 * @outlen length of output buffer -- see crypto_rng_get_bytes
226 * @addtl_input additional information string input buffer
227 * @addtllen length of additional information string buffer
228 * @test_data filled test data
229 *
230 * return
231 *	see crypto_rng_get_bytes
232 */
233static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
234			unsigned char *outbuf, unsigned int outlen,
235			struct drbg_string *addtl,
236			struct drbg_test_data *test_data)
237{
238	crypto_rng_set_entropy(drng, test_data->testentropy->buf,
239			       test_data->testentropy->len);
240	return crypto_rng_generate(drng, addtl->buf, addtl->len,
241				   outbuf, outlen);
242}
243
244/*
245 * TEST code
246 *
247 * This is a wrapper to the kernel crypto API function of
248 * crypto_rng_reset() to allow the caller to provide test_data
249 *
250 * @drng DRBG handle -- see crypto_rng_reset
251 * @pers personalization string input buffer
252 * @perslen length of additional information string buffer
253 * @test_data filled test data
254 *
255 * return
256 *	see crypto_rng_reset
257 */
258static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
259					 struct drbg_string *pers,
260					 struct drbg_test_data *test_data)
261{
262	crypto_rng_set_entropy(drng, test_data->testentropy->buf,
263			       test_data->testentropy->len);
264	return crypto_rng_reset(drng, pers->buf, pers->len);
265}
266
267/* DRBG type flags */
268#define DRBG_CTR	((drbg_flag_t)1<<0)
269#define DRBG_HMAC	((drbg_flag_t)1<<1)
270#define DRBG_HASH	((drbg_flag_t)1<<2)
271#define DRBG_TYPE_MASK	(DRBG_CTR | DRBG_HMAC | DRBG_HASH)
272/* DRBG strength flags */
273#define DRBG_STRENGTH128	((drbg_flag_t)1<<3)
274#define DRBG_STRENGTH192	((drbg_flag_t)1<<4)
275#define DRBG_STRENGTH256	((drbg_flag_t)1<<5)
276#define DRBG_STRENGTH_MASK	(DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
277				 DRBG_STRENGTH256)
278
279enum drbg_prefixes {
280	DRBG_PREFIX0 = 0x00,
281	DRBG_PREFIX1,
282	DRBG_PREFIX2,
283	DRBG_PREFIX3
284};
285
286#endif /* _DRBG_H */
287