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