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 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 */ 65 struct drbg_string { 66 const unsigned char *buf; 67 size_t len; 68 struct list_head list; 69 }; 70 71 static 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 79 struct drbg_state; 80 typedef uint32_t drbg_flag_t; 81 82 struct 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 91 struct 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 }; 101 102 struct drbg_test_data { 103 struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */ 104 }; 105 106 struct drbg_state { 107 struct mutex drbg_mutex; /* 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_string test_data; 125 }; 126 127 static inline __u8 drbg_statelen(struct drbg_state *drbg) 128 { 129 if (drbg && drbg->core) 130 return drbg->core->statelen; 131 return 0; 132 } 133 134 static inline __u8 drbg_blocklen(struct drbg_state *drbg) 135 { 136 if (drbg && drbg->core) 137 return drbg->core->blocklen_bytes; 138 return 0; 139 } 140 141 static 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 } 147 148 static 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 } 153 154 static 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 } 168 169 static 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 * This is a wrapper to the kernel crypto API function of 181 * crypto_rng_generate() to allow the caller to provide additional data. 182 * 183 * @drng DRBG handle -- see crypto_rng_get_bytes 184 * @outbuf output buffer -- see crypto_rng_get_bytes 185 * @outlen length of output buffer -- see crypto_rng_get_bytes 186 * @addtl_input additional information string input buffer 187 * @addtllen length of additional information string buffer 188 * 189 * return 190 * see crypto_rng_get_bytes 191 */ 192 static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng, 193 unsigned char *outbuf, unsigned int outlen, 194 struct drbg_string *addtl) 195 { 196 return crypto_rng_generate(drng, addtl->buf, addtl->len, 197 outbuf, outlen); 198 } 199 200 /* 201 * TEST code 202 * 203 * This is a wrapper to the kernel crypto API function of 204 * crypto_rng_generate() to allow the caller to provide additional data and 205 * allow furnishing of test_data 206 * 207 * @drng DRBG handle -- see crypto_rng_get_bytes 208 * @outbuf output buffer -- see crypto_rng_get_bytes 209 * @outlen length of output buffer -- see crypto_rng_get_bytes 210 * @addtl_input additional information string input buffer 211 * @addtllen length of additional information string buffer 212 * @test_data filled test data 213 * 214 * return 215 * see crypto_rng_get_bytes 216 */ 217 static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng, 218 unsigned char *outbuf, unsigned int outlen, 219 struct drbg_string *addtl, 220 struct drbg_test_data *test_data) 221 { 222 crypto_rng_set_entropy(drng, test_data->testentropy->buf, 223 test_data->testentropy->len); 224 return crypto_rng_generate(drng, addtl->buf, addtl->len, 225 outbuf, outlen); 226 } 227 228 /* 229 * TEST code 230 * 231 * This is a wrapper to the kernel crypto API function of 232 * crypto_rng_reset() to allow the caller to provide test_data 233 * 234 * @drng DRBG handle -- see crypto_rng_reset 235 * @pers personalization string input buffer 236 * @perslen length of additional information string buffer 237 * @test_data filled test data 238 * 239 * return 240 * see crypto_rng_reset 241 */ 242 static inline int crypto_drbg_reset_test(struct crypto_rng *drng, 243 struct drbg_string *pers, 244 struct drbg_test_data *test_data) 245 { 246 crypto_rng_set_entropy(drng, test_data->testentropy->buf, 247 test_data->testentropy->len); 248 return crypto_rng_reset(drng, pers->buf, pers->len); 249 } 250 251 /* DRBG type flags */ 252 #define DRBG_CTR ((drbg_flag_t)1<<0) 253 #define DRBG_HMAC ((drbg_flag_t)1<<1) 254 #define DRBG_HASH ((drbg_flag_t)1<<2) 255 #define DRBG_TYPE_MASK (DRBG_CTR | DRBG_HMAC | DRBG_HASH) 256 /* DRBG strength flags */ 257 #define DRBG_STRENGTH128 ((drbg_flag_t)1<<3) 258 #define DRBG_STRENGTH192 ((drbg_flag_t)1<<4) 259 #define DRBG_STRENGTH256 ((drbg_flag_t)1<<5) 260 #define DRBG_STRENGTH_MASK (DRBG_STRENGTH128 | DRBG_STRENGTH192 | \ 261 DRBG_STRENGTH256) 262 263 enum drbg_prefixes { 264 DRBG_PREFIX0 = 0x00, 265 DRBG_PREFIX1, 266 DRBG_PREFIX2, 267 DRBG_PREFIX3 268 }; 269 270 #endif /* _DRBG_H */ 271