xref: /openbmc/linux/include/crypto/drbg.h (revision 2a598d0b)
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  */
67 struct drbg_string {
68 	const unsigned char *buf;
69 	size_t len;
70 	struct list_head list;
71 };
72 
73 static 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 
81 struct drbg_state;
82 typedef uint32_t drbg_flag_t;
83 
84 struct 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 
93 struct 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 
104 struct drbg_test_data {
105 	struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
106 };
107 
108 enum 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 
114 struct 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 
147 static inline __u8 drbg_statelen(struct drbg_state *drbg)
148 {
149 	if (drbg && drbg->core)
150 		return drbg->core->statelen;
151 	return 0;
152 }
153 
154 static 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 
161 static 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 
168 static 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 
174 static 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 
189 static 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  */
208 static 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  */
233 static 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  */
258 static 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 
279 enum drbg_prefixes {
280 	DRBG_PREFIX0 = 0x00,
281 	DRBG_PREFIX1,
282 	DRBG_PREFIX2,
283 	DRBG_PREFIX3
284 };
285 
286 #endif /* _DRBG_H */
287