linux/include/crypto/drbg.h
<<
>>
Prefs
   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 */
  67struct drbg_string {
  68        const unsigned char *buf;
  69        size_t len;
  70        struct list_head list;
  71};
  72
  73static 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
  81struct drbg_state;
  82typedef uint32_t drbg_flag_t;
  83
  84struct 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
  93struct 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
 104struct drbg_test_data {
 105        struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
 106};
 107
 108struct drbg_state {
 109        struct mutex drbg_mutex;        /* lock around DRBG */
 110        unsigned char *V;       /* internal state 10.1.1.1 1a) */
 111        unsigned char *Vbuf;
 112        /* hash: static value 10.1.1.1 1b) hmac / ctr: key */
 113        unsigned char *C;
 114        unsigned char *Cbuf;
 115        /* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
 116        size_t reseed_ctr;
 117        size_t reseed_threshold;
 118         /* some memory the DRBG can use for its operation */
 119        unsigned char *scratchpad;
 120        unsigned char *scratchpadbuf;
 121        void *priv_data;        /* Cipher handle */
 122
 123        struct crypto_skcipher *ctr_handle;     /* CTR mode cipher handle */
 124        struct skcipher_request *ctr_req;       /* CTR mode request handle */
 125        __u8 *outscratchpadbuf;                 /* CTR mode output scratchpad */
 126        __u8 *outscratchpad;                    /* CTR mode aligned outbuf */
 127        struct crypto_wait ctr_wait;            /* CTR mode async wait obj */
 128        struct scatterlist sg_in, sg_out;       /* CTR mode SGLs */
 129
 130        bool seeded;            /* DRBG fully seeded? */
 131        bool pr;                /* Prediction resistance enabled? */
 132        bool fips_primed;       /* Continuous test primed? */
 133        unsigned char *prev;    /* FIPS 140-2 continuous test value */
 134        struct work_struct seed_work;   /* asynchronous seeding support */
 135        struct crypto_rng *jent;
 136        const struct drbg_state_ops *d_ops;
 137        const struct drbg_core *core;
 138        struct drbg_string test_data;
 139        struct random_ready_callback random_ready;
 140};
 141
 142static inline __u8 drbg_statelen(struct drbg_state *drbg)
 143{
 144        if (drbg && drbg->core)
 145                return drbg->core->statelen;
 146        return 0;
 147}
 148
 149static inline __u8 drbg_blocklen(struct drbg_state *drbg)
 150{
 151        if (drbg && drbg->core)
 152                return drbg->core->blocklen_bytes;
 153        return 0;
 154}
 155
 156static inline __u8 drbg_keylen(struct drbg_state *drbg)
 157{
 158        if (drbg && drbg->core)
 159                return (drbg->core->statelen - drbg->core->blocklen_bytes);
 160        return 0;
 161}
 162
 163static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
 164{
 165        /* SP800-90A requires the limit 2**19 bits, but we return bytes */
 166        return (1 << 16);
 167}
 168
 169static inline size_t drbg_max_addtl(struct drbg_state *drbg)
 170{
 171        /* SP800-90A requires 2**35 bytes additional info str / pers str */
 172#if (__BITS_PER_LONG == 32)
 173        /*
 174         * SP800-90A allows smaller maximum numbers to be returned -- we
 175         * return SIZE_MAX - 1 to allow the verification of the enforcement
 176         * of this value in drbg_healthcheck_sanity.
 177         */
 178        return (SIZE_MAX - 1);
 179#else
 180        return (1UL<<35);
 181#endif
 182}
 183
 184static inline size_t drbg_max_requests(struct drbg_state *drbg)
 185{
 186        /* SP800-90A requires 2**48 maximum requests before reseeding */
 187#if (__BITS_PER_LONG == 32)
 188        return SIZE_MAX;
 189#else
 190        return (1UL<<48);
 191#endif
 192}
 193
 194/*
 195 * This is a wrapper to the kernel crypto API function of
 196 * crypto_rng_generate() to allow the caller to provide additional data.
 197 *
 198 * @drng DRBG handle -- see crypto_rng_get_bytes
 199 * @outbuf output buffer -- see crypto_rng_get_bytes
 200 * @outlen length of output buffer -- see crypto_rng_get_bytes
 201 * @addtl_input additional information string input buffer
 202 * @addtllen length of additional information string buffer
 203 *
 204 * return
 205 *      see crypto_rng_get_bytes
 206 */
 207static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
 208                        unsigned char *outbuf, unsigned int outlen,
 209                        struct drbg_string *addtl)
 210{
 211        return crypto_rng_generate(drng, addtl->buf, addtl->len,
 212                                   outbuf, outlen);
 213}
 214
 215/*
 216 * TEST code
 217 *
 218 * This is a wrapper to the kernel crypto API function of
 219 * crypto_rng_generate() to allow the caller to provide additional data and
 220 * allow furnishing of test_data
 221 *
 222 * @drng DRBG handle -- see crypto_rng_get_bytes
 223 * @outbuf output buffer -- see crypto_rng_get_bytes
 224 * @outlen length of output buffer -- see crypto_rng_get_bytes
 225 * @addtl_input additional information string input buffer
 226 * @addtllen length of additional information string buffer
 227 * @test_data filled test data
 228 *
 229 * return
 230 *      see crypto_rng_get_bytes
 231 */
 232static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
 233                        unsigned char *outbuf, unsigned int outlen,
 234                        struct drbg_string *addtl,
 235                        struct drbg_test_data *test_data)
 236{
 237        crypto_rng_set_entropy(drng, test_data->testentropy->buf,
 238                               test_data->testentropy->len);
 239        return crypto_rng_generate(drng, addtl->buf, addtl->len,
 240                                   outbuf, outlen);
 241}
 242
 243/*
 244 * TEST code
 245 *
 246 * This is a wrapper to the kernel crypto API function of
 247 * crypto_rng_reset() to allow the caller to provide test_data
 248 *
 249 * @drng DRBG handle -- see crypto_rng_reset
 250 * @pers personalization string input buffer
 251 * @perslen length of additional information string buffer
 252 * @test_data filled test data
 253 *
 254 * return
 255 *      see crypto_rng_reset
 256 */
 257static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
 258                                         struct drbg_string *pers,
 259                                         struct drbg_test_data *test_data)
 260{
 261        crypto_rng_set_entropy(drng, test_data->testentropy->buf,
 262                               test_data->testentropy->len);
 263        return crypto_rng_reset(drng, pers->buf, pers->len);
 264}
 265
 266/* DRBG type flags */
 267#define DRBG_CTR        ((drbg_flag_t)1<<0)
 268#define DRBG_HMAC       ((drbg_flag_t)1<<1)
 269#define DRBG_HASH       ((drbg_flag_t)1<<2)
 270#define DRBG_TYPE_MASK  (DRBG_CTR | DRBG_HMAC | DRBG_HASH)
 271/* DRBG strength flags */
 272#define DRBG_STRENGTH128        ((drbg_flag_t)1<<3)
 273#define DRBG_STRENGTH192        ((drbg_flag_t)1<<4)
 274#define DRBG_STRENGTH256        ((drbg_flag_t)1<<5)
 275#define DRBG_STRENGTH_MASK      (DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
 276                                 DRBG_STRENGTH256)
 277
 278enum drbg_prefixes {
 279        DRBG_PREFIX0 = 0x00,
 280        DRBG_PREFIX1,
 281        DRBG_PREFIX2,
 282        DRBG_PREFIX3
 283};
 284
 285#endif /* _DRBG_H */
 286