include/crypto/drbg.h

   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 */