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 <linux/module.h>
47#include <linux/crypto.h>
48#include <linux/slab.h>
49#include <crypto/internal/rng.h>
50#include <crypto/rng.h>
51#include <linux/fips.h>
52#include <linux/spinlock.h>
53#include <linux/list.h>
54
55/*
56 * Concatenation Helper and string operation helper
57 *
58 * SP800-90A requires the concatenation of different data. To avoid copying
59 * buffers around or allocate additional memory, the following data structure
60 * is used to point to the original memory with its size. In addition, it
61 * is used to build a linked list. The linked list defines the concatenation
62 * of individual buffers. The order of memory block referenced in that
63 * linked list determines the order of concatenation.
64 */
65struct drbg_string {
66	const unsigned char *buf;
67	size_t len;
68	struct list_head list;
69};
70
71static inline void drbg_string_fill(struct drbg_string *string,
72				    const unsigned char *buf, size_t len)
73{
74	string->buf = buf;
75	string->len = len;
76	INIT_LIST_HEAD(&string->list);
77}
78
79struct drbg_state;
80typedef uint32_t drbg_flag_t;
81
82struct drbg_core {
83	drbg_flag_t flags;	/* flags for the cipher */
84	__u8 statelen;		/* maximum state length */
85	__u8 blocklen_bytes;	/* block size of output in bytes */
86	char cra_name[CRYPTO_MAX_ALG_NAME]; /* mapping to kernel crypto API */
87	 /* kernel crypto API backend cipher name */
88	char backend_cra_name[CRYPTO_MAX_ALG_NAME];
89};
90
91struct drbg_state_ops {
92	int (*update)(struct drbg_state *drbg, struct list_head *seed,
93		      int reseed);
94	int (*generate)(struct drbg_state *drbg,
95			unsigned char *buf, unsigned int buflen,
96			struct list_head *addtl);
97	int (*crypto_init)(struct drbg_state *drbg);
98	int (*crypto_fini)(struct drbg_state *drbg);
99
100};
101
102struct drbg_test_data {
103	struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
104};
105
106struct drbg_state {
107	spinlock_t drbg_lock;	/* lock around DRBG */
108	unsigned char *V;	/* internal state 10.1.1.1 1a) */
109	/* hash: static value 10.1.1.1 1b) hmac / ctr: key */
110	unsigned char *C;
111	/* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
112	size_t reseed_ctr;
113	 /* some memory the DRBG can use for its operation */
114	unsigned char *scratchpad;
115	void *priv_data;	/* Cipher handle */
116	bool seeded;		/* DRBG fully seeded? */
117	bool pr;		/* Prediction resistance enabled? */
118#ifdef CONFIG_CRYPTO_FIPS
119	bool fips_primed;	/* Continuous test primed? */
120	unsigned char *prev;	/* FIPS 140-2 continuous test value */
121#endif
122	const struct drbg_state_ops *d_ops;
123	const struct drbg_core *core;
124	struct drbg_test_data *test_data;
125};
126
127static inline __u8 drbg_statelen(struct drbg_state *drbg)
128{
129	if (drbg && drbg->core)
130		return drbg->core->statelen;
131	return 0;
132}
133
134static inline __u8 drbg_blocklen(struct drbg_state *drbg)
135{
136	if (drbg && drbg->core)
137		return drbg->core->blocklen_bytes;
138	return 0;
139}
140
141static inline __u8 drbg_keylen(struct drbg_state *drbg)
142{
143	if (drbg && drbg->core)
144		return (drbg->core->statelen - drbg->core->blocklen_bytes);
145	return 0;
146}
147
148static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
149{
150	/* SP800-90A requires the limit 2**19 bits, but we return bytes */
151	return (1 << 16);
152}
153
154static inline size_t drbg_max_addtl(struct drbg_state *drbg)
155{
156	/* SP800-90A requires 2**35 bytes additional info str / pers str */
157#if (__BITS_PER_LONG == 32)
158	/*
159	 * SP800-90A allows smaller maximum numbers to be returned -- we
160	 * return SIZE_MAX - 1 to allow the verification of the enforcement
161	 * of this value in drbg_healthcheck_sanity.
162	 */
163	return (SIZE_MAX - 1);
164#else
165	return (1UL<<35);
166#endif
167}
168
169static inline size_t drbg_max_requests(struct drbg_state *drbg)
170{
171	/* SP800-90A requires 2**48 maximum requests before reseeding */
172#if (__BITS_PER_LONG == 32)
173	return SIZE_MAX;
174#else
175	return (1UL<<48);
176#endif
177}
178
179/*
180 * kernel crypto API input data structure for DRBG generate in case dlen
181 * is set to 0
182 */
183struct drbg_gen {
184	unsigned char *outbuf;	/* output buffer for random numbers */
185	unsigned int outlen;	/* size of output buffer */
186	struct drbg_string *addtl;	/* additional information string */
187	struct drbg_test_data *test_data;	/* test data */
188};
189
190/*
191 * This is a wrapper to the kernel crypto API function of
192 * crypto_rng_get_bytes() to allow the caller to provide additional data.
193 *
194 * @drng DRBG handle -- see crypto_rng_get_bytes
195 * @outbuf output buffer -- see crypto_rng_get_bytes
196 * @outlen length of output buffer -- see crypto_rng_get_bytes
197 * @addtl_input additional information string input buffer
198 * @addtllen length of additional information string buffer
199 *
200 * return
201 *	see crypto_rng_get_bytes
202 */
203static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
204			unsigned char *outbuf, unsigned int outlen,
205			struct drbg_string *addtl)
206{
207	int ret;
208	struct drbg_gen genbuf;
209	genbuf.outbuf = outbuf;
210	genbuf.outlen = outlen;
211	genbuf.addtl = addtl;
212	genbuf.test_data = NULL;
213	ret = crypto_rng_get_bytes(drng, (u8 *)&genbuf, 0);
214	return ret;
215}
216
217/*
218 * TEST code
219 *
220 * This is a wrapper to the kernel crypto API function of
221 * crypto_rng_get_bytes() to allow the caller to provide additional data and
222 * allow furnishing of test_data
223 *
224 * @drng DRBG handle -- see crypto_rng_get_bytes
225 * @outbuf output buffer -- see crypto_rng_get_bytes
226 * @outlen length of output buffer -- see crypto_rng_get_bytes
227 * @addtl_input additional information string input buffer
228 * @addtllen length of additional information string buffer
229 * @test_data filled test data
230 *
231 * return
232 *	see crypto_rng_get_bytes
233 */
234static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
235			unsigned char *outbuf, unsigned int outlen,
236			struct drbg_string *addtl,
237			struct drbg_test_data *test_data)
238{
239	int ret;
240	struct drbg_gen genbuf;
241	genbuf.outbuf = outbuf;
242	genbuf.outlen = outlen;
243	genbuf.addtl = addtl;
244	genbuf.test_data = test_data;
245	ret = crypto_rng_get_bytes(drng, (u8 *)&genbuf, 0);
246	return ret;
247}
248
249/*
250 * TEST code
251 *
252 * This is a wrapper to the kernel crypto API function of
253 * crypto_rng_reset() to allow the caller to provide test_data
254 *
255 * @drng DRBG handle -- see crypto_rng_reset
256 * @pers personalization string input buffer
257 * @perslen length of additional information string buffer
258 * @test_data filled test data
259 *
260 * return
261 *	see crypto_rng_reset
262 */
263static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
264					 struct drbg_string *pers,
265					 struct drbg_test_data *test_data)
266{
267	int ret;
268	struct drbg_gen genbuf;
269	genbuf.outbuf = NULL;
270	genbuf.outlen = 0;
271	genbuf.addtl = pers;
272	genbuf.test_data = test_data;
273	ret = crypto_rng_reset(drng, (u8 *)&genbuf, 0);
274	return ret;
275}
276
277/* DRBG type flags */
278#define DRBG_CTR	((drbg_flag_t)1<<0)
279#define DRBG_HMAC	((drbg_flag_t)1<<1)
280#define DRBG_HASH	((drbg_flag_t)1<<2)
281#define DRBG_TYPE_MASK	(DRBG_CTR | DRBG_HMAC | DRBG_HASH)
282/* DRBG strength flags */
283#define DRBG_STRENGTH128	((drbg_flag_t)1<<3)
284#define DRBG_STRENGTH192	((drbg_flag_t)1<<4)
285#define DRBG_STRENGTH256	((drbg_flag_t)1<<5)
286#define DRBG_STRENGTH_MASK	(DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
287				 DRBG_STRENGTH256)
288
289enum drbg_prefixes {
290	DRBG_PREFIX0 = 0x00,
291	DRBG_PREFIX1,
292	DRBG_PREFIX2,
293	DRBG_PREFIX3
294};
295
296#endif /* _DRBG_H */
297