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![Stephan Mueller](/assets/img/avatar_default.png)
The async seeding operation is triggered during initalization right after the first non-blocking seeding is completed. As required by the asynchronous operation of random.c, a callback function is provided that is triggered by random.c once entropy is available. That callback function performs the actual seeding of the DRBG. CC: Andreas Steffen <andreas.steffen@strongswan.org> CC: Theodore Ts'o <tytso@mit.edu> CC: Sandy Harris <sandyinchina@gmail.com> Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
274 lines
8.5 KiB
C
274 lines
8.5 KiB
C
/*
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* DRBG based on NIST SP800-90A
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*
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* Copyright Stephan Mueller <smueller@chronox.de>, 2014
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, and the entire permission notice in its entirety,
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* including the disclaimer of warranties.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* ALTERNATIVELY, this product may be distributed under the terms of
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* the GNU General Public License, in which case the provisions of the GPL are
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* required INSTEAD OF the above restrictions. (This clause is
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* necessary due to a potential bad interaction between the GPL and
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* the restrictions contained in a BSD-style copyright.)
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
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* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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* USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*/
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#ifndef _DRBG_H
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#define _DRBG_H
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#include <linux/random.h>
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#include <linux/scatterlist.h>
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#include <crypto/hash.h>
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#include <linux/module.h>
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#include <linux/crypto.h>
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#include <linux/slab.h>
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#include <crypto/internal/rng.h>
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#include <crypto/rng.h>
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#include <linux/fips.h>
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#include <linux/mutex.h>
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#include <linux/list.h>
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#include <linux/workqueue.h>
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/*
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* Concatenation Helper and string operation helper
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*
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* SP800-90A requires the concatenation of different data. To avoid copying
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* buffers around or allocate additional memory, the following data structure
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* is used to point to the original memory with its size. In addition, it
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* is used to build a linked list. The linked list defines the concatenation
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* of individual buffers. The order of memory block referenced in that
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* linked list determines the order of concatenation.
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*/
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struct drbg_string {
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const unsigned char *buf;
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size_t len;
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struct list_head list;
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};
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static inline void drbg_string_fill(struct drbg_string *string,
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const unsigned char *buf, size_t len)
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{
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string->buf = buf;
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string->len = len;
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INIT_LIST_HEAD(&string->list);
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}
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struct drbg_state;
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typedef uint32_t drbg_flag_t;
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struct drbg_core {
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drbg_flag_t flags; /* flags for the cipher */
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__u8 statelen; /* maximum state length */
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__u8 blocklen_bytes; /* block size of output in bytes */
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char cra_name[CRYPTO_MAX_ALG_NAME]; /* mapping to kernel crypto API */
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/* kernel crypto API backend cipher name */
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char backend_cra_name[CRYPTO_MAX_ALG_NAME];
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};
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struct drbg_state_ops {
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int (*update)(struct drbg_state *drbg, struct list_head *seed,
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int reseed);
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int (*generate)(struct drbg_state *drbg,
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unsigned char *buf, unsigned int buflen,
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struct list_head *addtl);
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int (*crypto_init)(struct drbg_state *drbg);
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int (*crypto_fini)(struct drbg_state *drbg);
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};
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struct drbg_test_data {
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struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
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};
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struct drbg_state {
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struct mutex drbg_mutex; /* lock around DRBG */
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unsigned char *V; /* internal state 10.1.1.1 1a) */
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/* hash: static value 10.1.1.1 1b) hmac / ctr: key */
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unsigned char *C;
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/* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
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size_t reseed_ctr;
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/* some memory the DRBG can use for its operation */
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unsigned char *scratchpad;
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void *priv_data; /* Cipher handle */
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bool seeded; /* DRBG fully seeded? */
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bool pr; /* Prediction resistance enabled? */
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#ifdef CONFIG_CRYPTO_FIPS
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bool fips_primed; /* Continuous test primed? */
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unsigned char *prev; /* FIPS 140-2 continuous test value */
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#endif
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struct work_struct seed_work; /* asynchronous seeding support */
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u8 *seed_buf; /* buffer holding the seed */
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size_t seed_buf_len;
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const struct drbg_state_ops *d_ops;
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const struct drbg_core *core;
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struct drbg_string test_data;
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};
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static inline __u8 drbg_statelen(struct drbg_state *drbg)
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{
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if (drbg && drbg->core)
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return drbg->core->statelen;
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return 0;
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}
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static inline __u8 drbg_blocklen(struct drbg_state *drbg)
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{
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if (drbg && drbg->core)
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return drbg->core->blocklen_bytes;
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return 0;
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}
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static inline __u8 drbg_keylen(struct drbg_state *drbg)
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{
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if (drbg && drbg->core)
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return (drbg->core->statelen - drbg->core->blocklen_bytes);
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return 0;
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}
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static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
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{
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/* SP800-90A requires the limit 2**19 bits, but we return bytes */
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return (1 << 16);
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}
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static inline size_t drbg_max_addtl(struct drbg_state *drbg)
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{
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/* SP800-90A requires 2**35 bytes additional info str / pers str */
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#if (__BITS_PER_LONG == 32)
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/*
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* SP800-90A allows smaller maximum numbers to be returned -- we
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* return SIZE_MAX - 1 to allow the verification of the enforcement
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* of this value in drbg_healthcheck_sanity.
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*/
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return (SIZE_MAX - 1);
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#else
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return (1UL<<35);
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#endif
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}
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static inline size_t drbg_max_requests(struct drbg_state *drbg)
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{
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/* SP800-90A requires 2**48 maximum requests before reseeding */
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#if (__BITS_PER_LONG == 32)
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return SIZE_MAX;
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#else
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return (1UL<<48);
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#endif
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}
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/*
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* This is a wrapper to the kernel crypto API function of
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* crypto_rng_generate() to allow the caller to provide additional data.
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*
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* @drng DRBG handle -- see crypto_rng_get_bytes
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* @outbuf output buffer -- see crypto_rng_get_bytes
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* @outlen length of output buffer -- see crypto_rng_get_bytes
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* @addtl_input additional information string input buffer
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* @addtllen length of additional information string buffer
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*
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* return
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* see crypto_rng_get_bytes
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*/
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static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
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unsigned char *outbuf, unsigned int outlen,
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struct drbg_string *addtl)
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{
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return crypto_rng_generate(drng, addtl->buf, addtl->len,
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outbuf, outlen);
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}
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/*
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* TEST code
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*
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* This is a wrapper to the kernel crypto API function of
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* crypto_rng_generate() to allow the caller to provide additional data and
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* allow furnishing of test_data
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*
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* @drng DRBG handle -- see crypto_rng_get_bytes
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* @outbuf output buffer -- see crypto_rng_get_bytes
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* @outlen length of output buffer -- see crypto_rng_get_bytes
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* @addtl_input additional information string input buffer
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* @addtllen length of additional information string buffer
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* @test_data filled test data
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*
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* return
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* see crypto_rng_get_bytes
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*/
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static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
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unsigned char *outbuf, unsigned int outlen,
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struct drbg_string *addtl,
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struct drbg_test_data *test_data)
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{
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crypto_rng_set_entropy(drng, test_data->testentropy->buf,
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test_data->testentropy->len);
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return crypto_rng_generate(drng, addtl->buf, addtl->len,
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outbuf, outlen);
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}
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/*
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* TEST code
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*
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* This is a wrapper to the kernel crypto API function of
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* crypto_rng_reset() to allow the caller to provide test_data
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*
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* @drng DRBG handle -- see crypto_rng_reset
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* @pers personalization string input buffer
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* @perslen length of additional information string buffer
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* @test_data filled test data
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*
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* return
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* see crypto_rng_reset
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*/
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static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
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struct drbg_string *pers,
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struct drbg_test_data *test_data)
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{
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crypto_rng_set_entropy(drng, test_data->testentropy->buf,
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test_data->testentropy->len);
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return crypto_rng_reset(drng, pers->buf, pers->len);
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}
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/* DRBG type flags */
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#define DRBG_CTR ((drbg_flag_t)1<<0)
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#define DRBG_HMAC ((drbg_flag_t)1<<1)
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#define DRBG_HASH ((drbg_flag_t)1<<2)
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#define DRBG_TYPE_MASK (DRBG_CTR | DRBG_HMAC | DRBG_HASH)
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/* DRBG strength flags */
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#define DRBG_STRENGTH128 ((drbg_flag_t)1<<3)
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#define DRBG_STRENGTH192 ((drbg_flag_t)1<<4)
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#define DRBG_STRENGTH256 ((drbg_flag_t)1<<5)
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#define DRBG_STRENGTH_MASK (DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
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DRBG_STRENGTH256)
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enum drbg_prefixes {
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DRBG_PREFIX0 = 0x00,
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DRBG_PREFIX1,
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DRBG_PREFIX2,
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DRBG_PREFIX3
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};
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#endif /* _DRBG_H */
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