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 58 struct drbg_state; 59 typedef uint32_t drbg_flag_t; 60 61 struct 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 70 struct 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 81 struct drbg_test_data { 82 struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */ 83 }; 84 85 enum 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 91 struct 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 }; 123 124 static inline __u8 drbg_statelen(struct drbg_state *drbg) 125 { 126 if (drbg && drbg->core) 127 return drbg->core->statelen; 128 return 0; 129 } 130 131 static inline __u8 drbg_blocklen(struct drbg_state *drbg) 132 { 133 if (drbg && drbg->core) 134 return drbg->core->blocklen_bytes; 135 return 0; 136 } 137 138 static 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 } 144 145 static 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 } 150 151 static 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 } 165 166 static 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 */ 185 static 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(drng, addtl->buf, addtl->len, 190 outbuf, 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 */ 210 static 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(drng, test_data->testentropy->buf, 216 test_data->testentropy->len); 217 return crypto_rng_generate(drng, addtl->buf, addtl->len, 218 outbuf, 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 */ 235 static 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(drng, test_data->testentropy->buf, 240 test_data->testentropy->len); 241 return crypto_rng_reset(drng, pers->buf, 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) 255 256 enum drbg_prefixes { 257 DRBG_PREFIX0 = 0x00, 258 DRBG_PREFIX1, 259 DRBG_PREFIX2, 260 DRBG_PREFIX3 261 }; 262 263 #endif /* _DRBG_H */ 264