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 struct drbg_state { 109 struct mutex drbg_mutex; /* lock around DRBG */ 110 unsigned char *V; /* internal state 10.1.1.1 1a) */ 111 unsigned char *Vbuf; 112 /* hash: static value 10.1.1.1 1b) hmac / ctr: key */ 113 unsigned char *C; 114 unsigned char *Cbuf; 115 /* Number of RNG requests since last reseed -- 10.1.1.1 1c) */ 116 size_t reseed_ctr; 117 size_t reseed_threshold; 118 /* some memory the DRBG can use for its operation */ 119 unsigned char *scratchpad; 120 unsigned char *scratchpadbuf; 121 void *priv_data; /* Cipher handle */ 122 123 struct crypto_skcipher *ctr_handle; /* CTR mode cipher handle */ 124 struct skcipher_request *ctr_req; /* CTR mode request handle */ 125 __u8 *outscratchpadbuf; /* CTR mode output scratchpad */ 126 __u8 *outscratchpad; /* CTR mode aligned outbuf */ 127 struct crypto_wait ctr_wait; /* CTR mode async wait obj */ 128 struct scatterlist sg_in, sg_out; /* CTR mode SGLs */ 129 130 bool seeded; /* DRBG fully seeded? */ 131 bool pr; /* Prediction resistance enabled? */ 132 struct work_struct seed_work; /* asynchronous seeding support */ 133 struct crypto_rng *jent; 134 const struct drbg_state_ops *d_ops; 135 const struct drbg_core *core; 136 struct drbg_string test_data; 137 struct random_ready_callback random_ready; 138 }; 139 140 static inline __u8 drbg_statelen(struct drbg_state *drbg) 141 { 142 if (drbg && drbg->core) 143 return drbg->core->statelen; 144 return 0; 145 } 146 147 static inline __u8 drbg_blocklen(struct drbg_state *drbg) 148 { 149 if (drbg && drbg->core) 150 return drbg->core->blocklen_bytes; 151 return 0; 152 } 153 154 static inline __u8 drbg_keylen(struct drbg_state *drbg) 155 { 156 if (drbg && drbg->core) 157 return (drbg->core->statelen - drbg->core->blocklen_bytes); 158 return 0; 159 } 160 161 static inline size_t drbg_max_request_bytes(struct drbg_state *drbg) 162 { 163 /* SP800-90A requires the limit 2**19 bits, but we return bytes */ 164 return (1 << 16); 165 } 166 167 static inline size_t drbg_max_addtl(struct drbg_state *drbg) 168 { 169 /* SP800-90A requires 2**35 bytes additional info str / pers str */ 170 #if (__BITS_PER_LONG == 32) 171 /* 172 * SP800-90A allows smaller maximum numbers to be returned -- we 173 * return SIZE_MAX - 1 to allow the verification of the enforcement 174 * of this value in drbg_healthcheck_sanity. 175 */ 176 return (SIZE_MAX - 1); 177 #else 178 return (1UL<<35); 179 #endif 180 } 181 182 static inline size_t drbg_max_requests(struct drbg_state *drbg) 183 { 184 /* SP800-90A requires 2**48 maximum requests before reseeding */ 185 #if (__BITS_PER_LONG == 32) 186 return SIZE_MAX; 187 #else 188 return (1UL<<48); 189 #endif 190 } 191 192 /* 193 * This is a wrapper to the kernel crypto API function of 194 * crypto_rng_generate() to allow the caller to provide additional data. 195 * 196 * @drng DRBG handle -- see crypto_rng_get_bytes 197 * @outbuf output buffer -- see crypto_rng_get_bytes 198 * @outlen length of output buffer -- see crypto_rng_get_bytes 199 * @addtl_input additional information string input buffer 200 * @addtllen length of additional information string buffer 201 * 202 * return 203 * see crypto_rng_get_bytes 204 */ 205 static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng, 206 unsigned char *outbuf, unsigned int outlen, 207 struct drbg_string *addtl) 208 { 209 return crypto_rng_generate(drng, addtl->buf, addtl->len, 210 outbuf, outlen); 211 } 212 213 /* 214 * TEST code 215 * 216 * This is a wrapper to the kernel crypto API function of 217 * crypto_rng_generate() to allow the caller to provide additional data and 218 * allow furnishing of test_data 219 * 220 * @drng DRBG handle -- see crypto_rng_get_bytes 221 * @outbuf output buffer -- see crypto_rng_get_bytes 222 * @outlen length of output buffer -- see crypto_rng_get_bytes 223 * @addtl_input additional information string input buffer 224 * @addtllen length of additional information string buffer 225 * @test_data filled test data 226 * 227 * return 228 * see crypto_rng_get_bytes 229 */ 230 static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng, 231 unsigned char *outbuf, unsigned int outlen, 232 struct drbg_string *addtl, 233 struct drbg_test_data *test_data) 234 { 235 crypto_rng_set_entropy(drng, test_data->testentropy->buf, 236 test_data->testentropy->len); 237 return crypto_rng_generate(drng, addtl->buf, addtl->len, 238 outbuf, outlen); 239 } 240 241 /* 242 * TEST code 243 * 244 * This is a wrapper to the kernel crypto API function of 245 * crypto_rng_reset() to allow the caller to provide test_data 246 * 247 * @drng DRBG handle -- see crypto_rng_reset 248 * @pers personalization string input buffer 249 * @perslen length of additional information string buffer 250 * @test_data filled test data 251 * 252 * return 253 * see crypto_rng_reset 254 */ 255 static inline int crypto_drbg_reset_test(struct crypto_rng *drng, 256 struct drbg_string *pers, 257 struct drbg_test_data *test_data) 258 { 259 crypto_rng_set_entropy(drng, test_data->testentropy->buf, 260 test_data->testentropy->len); 261 return crypto_rng_reset(drng, pers->buf, pers->len); 262 } 263 264 /* DRBG type flags */ 265 #define DRBG_CTR ((drbg_flag_t)1<<0) 266 #define DRBG_HMAC ((drbg_flag_t)1<<1) 267 #define DRBG_HASH ((drbg_flag_t)1<<2) 268 #define DRBG_TYPE_MASK (DRBG_CTR | DRBG_HMAC | DRBG_HASH) 269 /* DRBG strength flags */ 270 #define DRBG_STRENGTH128 ((drbg_flag_t)1<<3) 271 #define DRBG_STRENGTH192 ((drbg_flag_t)1<<4) 272 #define DRBG_STRENGTH256 ((drbg_flag_t)1<<5) 273 #define DRBG_STRENGTH_MASK (DRBG_STRENGTH128 | DRBG_STRENGTH192 | \ 274 DRBG_STRENGTH256) 275 276 enum drbg_prefixes { 277 DRBG_PREFIX0 = 0x00, 278 DRBG_PREFIX1, 279 DRBG_PREFIX2, 280 DRBG_PREFIX3 281 }; 282 283 #endif /* _DRBG_H */ 284