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