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