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(tfm: drng, src: addtl->buf, slen: addtl->len,
190 dst: outbuf, dlen: 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(tfm: drng, data: test_data->testentropy->buf,
216 len: test_data->testentropy->len);
217 return crypto_rng_generate(tfm: drng, src: addtl->buf, slen: addtl->len,
218 dst: outbuf, dlen: 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(tfm: drng, data: test_data->testentropy->buf,
240 len: test_data->testentropy->len);
241 return crypto_rng_reset(tfm: drng, seed: pers->buf, slen: 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 */
264

source code of linux/include/crypto/drbg.h