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
  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         __u8 blocklen_bytes;    /* block size of output in bytes */
  86         char cra_name[CRYPTO_MAX_ALG_NAME]; /* mapping to kernel crypto API */
  87          /* kernel crypto API backend cipher name */
  88         char backend_cra_name[CRYPTO_MAX_ALG_NAME];
  89 };
  90
  91 struct drbg_state_ops {
  92         int (*update)(struct drbg_state *drbg, struct list_head *seed,
  93                       int reseed);
  94         int (*generate)(struct drbg_state *drbg,
  95                         unsigned char *buf, unsigned int buflen,
  96                         struct list_head *addtl);
  97         int (*crypto_init)(struct drbg_state *drbg);
  98         int (*crypto_fini)(struct drbg_state *drbg);
  99
 100 };
 101
 102 struct drbg_test_data {
 103         struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
 104 };
 105
 106 struct drbg_state {
 107         struct mutex drbg_mutex;        /* lock around DRBG */
 108         unsigned char *V;       /* internal state 10.1.1.1 1a) */
 109         /* hash: static value 10.1.1.1 1b) hmac / ctr: key */
 110         unsigned char *C;
 111         /* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
 112         size_t reseed_ctr;
 113          /* some memory the DRBG can use for its operation */
 114         unsigned char *scratchpad;
 115         void *priv_data;        /* Cipher handle */
 116         bool seeded;            /* DRBG fully seeded? */
 117         bool pr;                /* Prediction resistance enabled? */
 118 #ifdef CONFIG_CRYPTO_FIPS
 119         bool fips_primed;       /* Continuous test primed? */
 120         unsigned char *prev;    /* FIPS 140-2 continuous test value */
 121 #endif
 122         const struct drbg_state_ops *d_ops;
 123         const struct drbg_core *core;
 124         struct drbg_test_data *test_data;
 125 };
 126
 127 static inline __u8 drbg_statelen(struct drbg_state *drbg)
 128 {
 129         if (drbg && drbg->core)
 130                 return drbg->core->statelen;
 131         return 0;
 132 }
 133
 134 static inline __u8 drbg_blocklen(struct drbg_state *drbg)
 135 {
 136         if (drbg && drbg->core)
 137                 return drbg->core->blocklen_bytes;
 138         return 0;
 139 }
 140
 141 static inline __u8 drbg_keylen(struct drbg_state *drbg)
 142 {
 143         if (drbg && drbg->core)
 144                 return (drbg->core->statelen - drbg->core->blocklen_bytes);
 145         return 0;
 146 }
 147
 148 static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
 149 {
 150         /* SP800-90A requires the limit 2**19 bits, but we return bytes */
 151         return (1 << 16);
 152 }
 153
 154 static inline size_t drbg_max_addtl(struct drbg_state *drbg)
 155 {
 156         /* SP800-90A requires 2**35 bytes additional info str / pers str */
 157 #if (__BITS_PER_LONG == 32)
 158         /*
 159          * SP800-90A allows smaller maximum numbers to be returned -- we
 160          * return SIZE_MAX - 1 to allow the verification of the enforcement
 161          * of this value in drbg_healthcheck_sanity.
 162          */
 163         return (SIZE_MAX - 1);
 164 #else
 165         return (1UL<<35);
 166 #endif
 167 }
 168
 169 static inline size_t drbg_max_requests(struct drbg_state *drbg)
 170 {
 171         /* SP800-90A requires 2**48 maximum requests before reseeding */
 172 #if (__BITS_PER_LONG == 32)
 173         return SIZE_MAX;
 174 #else
 175         return (1UL<<48);
 176 #endif
 177 }
 178
 179 /*
 180  * kernel crypto API input data structure for DRBG generate in case dlen
 181  * is set to 0
 182  */
 183 struct drbg_gen {
 184         unsigned char *outbuf;  /* output buffer for random numbers */
 185         unsigned int outlen;    /* size of output buffer */
 186         struct drbg_string *addtl;      /* additional information string */
 187         struct drbg_test_data *test_data;       /* test data */
 188 };
 189
 190 /*
 191  * This is a wrapper to the kernel crypto API function of
 192  * crypto_rng_get_bytes() to allow the caller to provide additional data.
 193  *
 194  * @drng DRBG handle -- see crypto_rng_get_bytes
 195  * @outbuf output buffer -- see crypto_rng_get_bytes
 196  * @outlen length of output buffer -- see crypto_rng_get_bytes
 197  * @addtl_input additional information string input buffer
 198  * @addtllen length of additional information string buffer
 199  *
 200  * return
 201  *      see crypto_rng_get_bytes
 202  */
 203 static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
 204                         unsigned char *outbuf, unsigned int outlen,
 205                         struct drbg_string *addtl)
 206 {
 207         int ret;
 208         struct drbg_gen genbuf;
 209         genbuf.outbuf = outbuf;
 210         genbuf.outlen = outlen;
 211         genbuf.addtl = addtl;
 212         genbuf.test_data = NULL;
 213         ret = crypto_rng_get_bytes(drng, (u8 *)&genbuf, 0);
 214         return ret;
 215 }
 216
 217 /*
 218  * TEST code
 219  *
 220  * This is a wrapper to the kernel crypto API function of
 221  * crypto_rng_get_bytes() to allow the caller to provide additional data and
 222  * allow furnishing of test_data
 223  *
 224  * @drng DRBG handle -- see crypto_rng_get_bytes
 225  * @outbuf output buffer -- see crypto_rng_get_bytes
 226  * @outlen length of output buffer -- see crypto_rng_get_bytes
 227  * @addtl_input additional information string input buffer
 228  * @addtllen length of additional information string buffer
 229  * @test_data filled test data
 230  *
 231  * return
 232  *      see crypto_rng_get_bytes
 233  */
 234 static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
 235                         unsigned char *outbuf, unsigned int outlen,
 236                         struct drbg_string *addtl,
 237                         struct drbg_test_data *test_data)
 238 {
 239         int ret;
 240         struct drbg_gen genbuf;
 241         genbuf.outbuf = outbuf;
 242         genbuf.outlen = outlen;
 243         genbuf.addtl = addtl;
 244         genbuf.test_data = test_data;
 245         ret = crypto_rng_get_bytes(drng, (u8 *)&genbuf, 0);
 246         return ret;
 247 }
 248
 249 /*
 250  * TEST code
 251  *
 252  * This is a wrapper to the kernel crypto API function of
 253  * crypto_rng_reset() to allow the caller to provide test_data
 254  *
 255  * @drng DRBG handle -- see crypto_rng_reset
 256  * @pers personalization string input buffer
 257  * @perslen length of additional information string buffer
 258  * @test_data filled test data
 259  *
 260  * return
 261  *      see crypto_rng_reset
 262  */
 263 static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
 264                                          struct drbg_string *pers,
 265                                          struct drbg_test_data *test_data)
 266 {
 267         int ret;
 268         struct drbg_gen genbuf;
 269         genbuf.outbuf = NULL;
 270         genbuf.outlen = 0;
 271         genbuf.addtl = pers;
 272         genbuf.test_data = test_data;
 273         ret = crypto_rng_reset(drng, (u8 *)&genbuf, 0);
 274         return ret;
 275 }
 276
 277 /* DRBG type flags */
 278 #define DRBG_CTR        ((drbg_flag_t)1<<0)
 279 #define DRBG_HMAC       ((drbg_flag_t)1<<1)
 280 #define DRBG_HASH       ((drbg_flag_t)1<<2)
 281 #define DRBG_TYPE_MASK  (DRBG_CTR | DRBG_HMAC | DRBG_HASH)
 282 /* DRBG strength flags */
 283 #define DRBG_STRENGTH128        ((drbg_flag_t)1<<3)
 284 #define DRBG_STRENGTH192        ((drbg_flag_t)1<<4)
 285 #define DRBG_STRENGTH256        ((drbg_flag_t)1<<5)
 286 #define DRBG_STRENGTH_MASK      (DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
 287                                  DRBG_STRENGTH256)
 288
 289 enum drbg_prefixes {
 290         DRBG_PREFIX0 = 0x00,
 291         DRBG_PREFIX1,
 292         DRBG_PREFIX2,
 293         DRBG_PREFIX3
 294 };
 295
 296 #endif /* _DRBG_H */