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/spinlock.h>
  53 #include <linux/list.h>
  54
  55 /*
  56  * Concatenation Helper and string operation helper
  57  *
  58  * SP800-90A requires the concatenation of different data. To avoid copying
  59  * buffers around or allocate additional memory, the following data structure
  60  * is used to point to the original memory with its size. In addition, it
  61  * is used to build a linked list. The linked list defines the concatenation
  62  * of individual buffers. The order of memory block referenced in that
  63  * linked list determines the order of concatenation.
  64  */
  65 struct drbg_string {
  66         const unsigned char *buf;
  67         size_t len;
  68         struct list_head list;
  69 };
  70
  71 static inline void drbg_string_fill(struct drbg_string *string,
  72                                     const unsigned char *buf, size_t len)
  73 {
  74         string->buf = buf;
  75         string->len = len;
  76         INIT_LIST_HEAD(&string->list);
  77 }
  78
  79 struct drbg_state;
  80 typedef uint32_t drbg_flag_t;
  81
  82 struct drbg_core {
  83         drbg_flag_t flags;      /* flags for the cipher */
  84         __u8 statelen;          /* maximum state length */
  85         /*
  86          * maximum length of personalization string or additional input
  87          * string -- exponent for base 2
  88          */
  89         __u8 max_addtllen;
  90         /* maximum bits per RNG request -- exponent for base 2*/
  91         __u8 max_bits;
  92         /* maximum number of requests -- exponent for base 2 */
  93         __u8 max_req;
  94         __u8 blocklen_bytes;    /* block size of output in bytes */
  95         char cra_name[CRYPTO_MAX_ALG_NAME]; /* mapping to kernel crypto API */
  96          /* kernel crypto API backend cipher name */
  97         char backend_cra_name[CRYPTO_MAX_ALG_NAME];
  98 };
  99
 100 struct drbg_state_ops {
 101         int (*update)(struct drbg_state *drbg, struct list_head *seed,
 102                       int reseed);
 103         int (*generate)(struct drbg_state *drbg,
 104                         unsigned char *buf, unsigned int buflen,
 105                         struct list_head *addtl);
 106         int (*crypto_init)(struct drbg_state *drbg);
 107         int (*crypto_fini)(struct drbg_state *drbg);
 108
 109 };
 110
 111 struct drbg_test_data {
 112         struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
 113 };
 114
 115 struct drbg_state {
 116         spinlock_t drbg_lock;   /* lock around DRBG */
 117         unsigned char *V;       /* internal state 10.1.1.1 1a) */
 118         /* hash: static value 10.1.1.1 1b) hmac / ctr: key */
 119         unsigned char *C;
 120         /* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
 121         size_t reseed_ctr;
 122          /* some memory the DRBG can use for its operation */
 123         unsigned char *scratchpad;
 124         void *priv_data;        /* Cipher handle */
 125         bool seeded;            /* DRBG fully seeded? */
 126         bool pr;                /* Prediction resistance enabled? */
 127 #ifdef CONFIG_CRYPTO_FIPS
 128         bool fips_primed;       /* Continuous test primed? */
 129         unsigned char *prev;    /* FIPS 140-2 continuous test value */
 130 #endif
 131         const struct drbg_state_ops *d_ops;
 132         const struct drbg_core *core;
 133         struct drbg_test_data *test_data;
 134 };
 135
 136 static inline __u8 drbg_statelen(struct drbg_state *drbg)
 137 {
 138         if (drbg && drbg->core)
 139                 return drbg->core->statelen;
 140         return 0;
 141 }
 142
 143 static inline __u8 drbg_blocklen(struct drbg_state *drbg)
 144 {
 145         if (drbg && drbg->core)
 146                 return drbg->core->blocklen_bytes;
 147         return 0;
 148 }
 149
 150 static inline __u8 drbg_keylen(struct drbg_state *drbg)
 151 {
 152         if (drbg && drbg->core)
 153                 return (drbg->core->statelen - drbg->core->blocklen_bytes);
 154         return 0;
 155 }
 156
 157 static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
 158 {
 159         /* max_bits is in bits, but buflen is in bytes */
 160         return (1 << (drbg->core->max_bits - 3));
 161 }
 162
 163 static inline size_t drbg_max_addtl(struct drbg_state *drbg)
 164 {
 165 #if (__BITS_PER_LONG == 32)
 166         /*
 167          * SP800-90A allows smaller maximum numbers to be returned -- we
 168          * return SIZE_MAX - 1 to allow the verification of the enforcement
 169          * of this value in drbg_healthcheck_sanity.
 170          */
 171         return (SIZE_MAX - 1);
 172 #else
 173         return (1UL<<(drbg->core->max_addtllen));
 174 #endif
 175 }
 176
 177 static inline size_t drbg_max_requests(struct drbg_state *drbg)
 178 {
 179 #if (__BITS_PER_LONG == 32)
 180         return SIZE_MAX;
 181 #else
 182         return (1UL<<(drbg->core->max_req));
 183 #endif
 184 }
 185
 186 /*
 187  * kernel crypto API input data structure for DRBG generate in case dlen
 188  * is set to 0
 189  */
 190 struct drbg_gen {
 191         unsigned char *outbuf;  /* output buffer for random numbers */
 192         unsigned int outlen;    /* size of output buffer */
 193         struct drbg_string *addtl;      /* additional information string */
 194         struct drbg_test_data *test_data;       /* test data */
 195 };
 196
 197 /*
 198  * This is a wrapper to the kernel crypto API function of
 199  * crypto_rng_get_bytes() to allow the caller to provide additional data.
 200  *
 201  * @drng DRBG handle -- see crypto_rng_get_bytes
 202  * @outbuf output buffer -- see crypto_rng_get_bytes
 203  * @outlen length of output buffer -- see crypto_rng_get_bytes
 204  * @addtl_input additional information string input buffer
 205  * @addtllen length of additional information string buffer
 206  *
 207  * return
 208  *      see crypto_rng_get_bytes
 209  */
 210 static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
 211                         unsigned char *outbuf, unsigned int outlen,
 212                         struct drbg_string *addtl)
 213 {
 214         int ret;
 215         struct drbg_gen genbuf;
 216         genbuf.outbuf = outbuf;
 217         genbuf.outlen = outlen;
 218         genbuf.addtl = addtl;
 219         genbuf.test_data = NULL;
 220         ret = crypto_rng_get_bytes(drng, (u8 *)&genbuf, 0);
 221         return ret;
 222 }
 223
 224 /*
 225  * TEST code
 226  *
 227  * This is a wrapper to the kernel crypto API function of
 228  * crypto_rng_get_bytes() to allow the caller to provide additional data and
 229  * allow furnishing of test_data
 230  *
 231  * @drng DRBG handle -- see crypto_rng_get_bytes
 232  * @outbuf output buffer -- see crypto_rng_get_bytes
 233  * @outlen length of output buffer -- see crypto_rng_get_bytes
 234  * @addtl_input additional information string input buffer
 235  * @addtllen length of additional information string buffer
 236  * @test_data filled test data
 237  *
 238  * return
 239  *      see crypto_rng_get_bytes
 240  */
 241 static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
 242                         unsigned char *outbuf, unsigned int outlen,
 243                         struct drbg_string *addtl,
 244                         struct drbg_test_data *test_data)
 245 {
 246         int ret;
 247         struct drbg_gen genbuf;
 248         genbuf.outbuf = outbuf;
 249         genbuf.outlen = outlen;
 250         genbuf.addtl = addtl;
 251         genbuf.test_data = test_data;
 252         ret = crypto_rng_get_bytes(drng, (u8 *)&genbuf, 0);
 253         return ret;
 254 }
 255
 256 /*
 257  * TEST code
 258  *
 259  * This is a wrapper to the kernel crypto API function of
 260  * crypto_rng_reset() to allow the caller to provide test_data
 261  *
 262  * @drng DRBG handle -- see crypto_rng_reset
 263  * @pers personalization string input buffer
 264  * @perslen length of additional information string buffer
 265  * @test_data filled test data
 266  *
 267  * return
 268  *      see crypto_rng_reset
 269  */
 270 static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
 271                                          struct drbg_string *pers,
 272                                          struct drbg_test_data *test_data)
 273 {
 274         int ret;
 275         struct drbg_gen genbuf;
 276         genbuf.outbuf = NULL;
 277         genbuf.outlen = 0;
 278         genbuf.addtl = pers;
 279         genbuf.test_data = test_data;
 280         ret = crypto_rng_reset(drng, (u8 *)&genbuf, 0);
 281         return ret;
 282 }
 283
 284 /* DRBG type flags */
 285 #define DRBG_CTR        ((drbg_flag_t)1<<0)
 286 #define DRBG_HMAC       ((drbg_flag_t)1<<1)
 287 #define DRBG_HASH       ((drbg_flag_t)1<<2)
 288 #define DRBG_TYPE_MASK  (DRBG_CTR | DRBG_HMAC | DRBG_HASH)
 289 /* DRBG strength flags */
 290 #define DRBG_STRENGTH128        ((drbg_flag_t)1<<3)
 291 #define DRBG_STRENGTH192        ((drbg_flag_t)1<<4)
 292 #define DRBG_STRENGTH256        ((drbg_flag_t)1<<5)
 293 #define DRBG_STRENGTH_MASK      (DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
 294                                  DRBG_STRENGTH256)
 295
 296 enum drbg_prefixes {
 297         DRBG_PREFIX0 = 0x00,
 298         DRBG_PREFIX1,
 299         DRBG_PREFIX2,
 300         DRBG_PREFIX3
 301 };
 302
 303 #endif /* _DRBG_H */