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+/*
+ * DRBG based on NIST SP800-90A
+ *
+ * Copyright Stephan Mueller <smueller@chronox.de>, 2014
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, and the entire permission notice in its entirety,
+ * including the disclaimer of warranties.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ * products derived from this software without specific prior
+ * written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of
+ * the GNU General Public License, in which case the provisions of the GPL are
+ * required INSTEAD OF the above restrictions. (This clause is
+ * necessary due to a potential bad interaction between the GPL and
+ * the restrictions contained in a BSD-style copyright.)
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
+ * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ */
+
+#ifndef _DRBG_H
+#define _DRBG_H
+
+
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <crypto/hash.h>
+#include <crypto/skcipher.h>
+#include <linux/module.h>
+#include <linux/crypto.h>
+#include <linux/slab.h>
+#include <crypto/internal/rng.h>
+#include <crypto/rng.h>
+#include <linux/fips.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/workqueue.h>
+
+/*
+ * Concatenation Helper and string operation helper
+ *
+ * SP800-90A requires the concatenation of different data. To avoid copying
+ * buffers around or allocate additional memory, the following data structure
+ * is used to point to the original memory with its size. In addition, it
+ * is used to build a linked list. The linked list defines the concatenation
+ * of individual buffers. The order of memory block referenced in that
+ * linked list determines the order of concatenation.
+ */
+struct drbg_string {
+ const unsigned char *buf;
+ size_t len;
+ struct list_head list;
+};
+
+static inline void drbg_string_fill(struct drbg_string *string,
+ const unsigned char *buf, size_t len)
+{
+ string->buf = buf;
+ string->len = len;
+ INIT_LIST_HEAD(&string->list);
+}
+
+struct drbg_state;
+typedef uint32_t drbg_flag_t;
+
+struct drbg_core {
+ drbg_flag_t flags; /* flags for the cipher */
+ __u8 statelen; /* maximum state length */
+ __u8 blocklen_bytes; /* block size of output in bytes */
+ char cra_name[CRYPTO_MAX_ALG_NAME]; /* mapping to kernel crypto API */
+ /* kernel crypto API backend cipher name */
+ char backend_cra_name[CRYPTO_MAX_ALG_NAME];
+};
+
+struct drbg_state_ops {
+ int (*update)(struct drbg_state *drbg, struct list_head *seed,
+ int reseed);
+ int (*generate)(struct drbg_state *drbg,
+ unsigned char *buf, unsigned int buflen,
+ struct list_head *addtl);
+ int (*crypto_init)(struct drbg_state *drbg);
+ int (*crypto_fini)(struct drbg_state *drbg);
+
+};
+
+struct drbg_test_data {
+ struct drbg_string *testentropy; /* TEST PARAMETER: test entropy */
+};
+
+enum drbg_seed_state {
+ DRBG_SEED_STATE_UNSEEDED,
+ DRBG_SEED_STATE_PARTIAL, /* Seeded with !rng_is_initialized() */
+ DRBG_SEED_STATE_FULL,
+};
+
+struct drbg_state {
+ struct mutex drbg_mutex; /* lock around DRBG */
+ unsigned char *V; /* internal state 10.1.1.1 1a) */
+ unsigned char *Vbuf;
+ /* hash: static value 10.1.1.1 1b) hmac / ctr: key */
+ unsigned char *C;
+ unsigned char *Cbuf;
+ /* Number of RNG requests since last reseed -- 10.1.1.1 1c) */
+ size_t reseed_ctr;
+ size_t reseed_threshold;
+ /* some memory the DRBG can use for its operation */
+ unsigned char *scratchpad;
+ unsigned char *scratchpadbuf;
+ void *priv_data; /* Cipher handle */
+
+ struct crypto_skcipher *ctr_handle; /* CTR mode cipher handle */
+ struct skcipher_request *ctr_req; /* CTR mode request handle */
+ __u8 *outscratchpadbuf; /* CTR mode output scratchpad */
+ __u8 *outscratchpad; /* CTR mode aligned outbuf */
+ struct crypto_wait ctr_wait; /* CTR mode async wait obj */
+ struct scatterlist sg_in, sg_out; /* CTR mode SGLs */
+
+ enum drbg_seed_state seeded; /* DRBG fully seeded? */
+ bool pr; /* Prediction resistance enabled? */
+ bool fips_primed; /* Continuous test primed? */
+ unsigned char *prev; /* FIPS 140-2 continuous test value */
+ struct crypto_rng *jent;
+ const struct drbg_state_ops *d_ops;
+ const struct drbg_core *core;
+ struct drbg_string test_data;
+};
+
+static inline __u8 drbg_statelen(struct drbg_state *drbg)
+{
+ if (drbg && drbg->core)
+ return drbg->core->statelen;
+ return 0;
+}
+
+static inline __u8 drbg_blocklen(struct drbg_state *drbg)
+{
+ if (drbg && drbg->core)
+ return drbg->core->blocklen_bytes;
+ return 0;
+}
+
+static inline __u8 drbg_keylen(struct drbg_state *drbg)
+{
+ if (drbg && drbg->core)
+ return (drbg->core->statelen - drbg->core->blocklen_bytes);
+ return 0;
+}
+
+static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
+{
+ /* SP800-90A requires the limit 2**19 bits, but we return bytes */
+ return (1 << 16);
+}
+
+static inline size_t drbg_max_addtl(struct drbg_state *drbg)
+{
+ /* SP800-90A requires 2**35 bytes additional info str / pers str */
+#if (__BITS_PER_LONG == 32)
+ /*
+ * SP800-90A allows smaller maximum numbers to be returned -- we
+ * return SIZE_MAX - 1 to allow the verification of the enforcement
+ * of this value in drbg_healthcheck_sanity.
+ */
+ return (SIZE_MAX - 1);
+#else
+ return (1UL<<35);
+#endif
+}
+
+static inline size_t drbg_max_requests(struct drbg_state *drbg)
+{
+ /* SP800-90A requires 2**48 maximum requests before reseeding */
+ return (1<<20);
+}
+
+/*
+ * This is a wrapper to the kernel crypto API function of
+ * crypto_rng_generate() to allow the caller to provide additional data.
+ *
+ * @drng DRBG handle -- see crypto_rng_get_bytes
+ * @outbuf output buffer -- see crypto_rng_get_bytes
+ * @outlen length of output buffer -- see crypto_rng_get_bytes
+ * @addtl_input additional information string input buffer
+ * @addtllen length of additional information string buffer
+ *
+ * return
+ * see crypto_rng_get_bytes
+ */
+static inline int crypto_drbg_get_bytes_addtl(struct crypto_rng *drng,
+ unsigned char *outbuf, unsigned int outlen,
+ struct drbg_string *addtl)
+{
+ return crypto_rng_generate(drng, addtl->buf, addtl->len,
+ outbuf, outlen);
+}
+
+/*
+ * TEST code
+ *
+ * This is a wrapper to the kernel crypto API function of
+ * crypto_rng_generate() to allow the caller to provide additional data and
+ * allow furnishing of test_data
+ *
+ * @drng DRBG handle -- see crypto_rng_get_bytes
+ * @outbuf output buffer -- see crypto_rng_get_bytes
+ * @outlen length of output buffer -- see crypto_rng_get_bytes
+ * @addtl_input additional information string input buffer
+ * @addtllen length of additional information string buffer
+ * @test_data filled test data
+ *
+ * return
+ * see crypto_rng_get_bytes
+ */
+static inline int crypto_drbg_get_bytes_addtl_test(struct crypto_rng *drng,
+ unsigned char *outbuf, unsigned int outlen,
+ struct drbg_string *addtl,
+ struct drbg_test_data *test_data)
+{
+ crypto_rng_set_entropy(drng, test_data->testentropy->buf,
+ test_data->testentropy->len);
+ return crypto_rng_generate(drng, addtl->buf, addtl->len,
+ outbuf, outlen);
+}
+
+/*
+ * TEST code
+ *
+ * This is a wrapper to the kernel crypto API function of
+ * crypto_rng_reset() to allow the caller to provide test_data
+ *
+ * @drng DRBG handle -- see crypto_rng_reset
+ * @pers personalization string input buffer
+ * @perslen length of additional information string buffer
+ * @test_data filled test data
+ *
+ * return
+ * see crypto_rng_reset
+ */
+static inline int crypto_drbg_reset_test(struct crypto_rng *drng,
+ struct drbg_string *pers,
+ struct drbg_test_data *test_data)
+{
+ crypto_rng_set_entropy(drng, test_data->testentropy->buf,
+ test_data->testentropy->len);
+ return crypto_rng_reset(drng, pers->buf, pers->len);
+}
+
+/* DRBG type flags */
+#define DRBG_CTR ((drbg_flag_t)1<<0)
+#define DRBG_HMAC ((drbg_flag_t)1<<1)
+#define DRBG_HASH ((drbg_flag_t)1<<2)
+#define DRBG_TYPE_MASK (DRBG_CTR | DRBG_HMAC | DRBG_HASH)
+/* DRBG strength flags */
+#define DRBG_STRENGTH128 ((drbg_flag_t)1<<3)
+#define DRBG_STRENGTH192 ((drbg_flag_t)1<<4)
+#define DRBG_STRENGTH256 ((drbg_flag_t)1<<5)
+#define DRBG_STRENGTH_MASK (DRBG_STRENGTH128 | DRBG_STRENGTH192 | \
+ DRBG_STRENGTH256)
+
+enum drbg_prefixes {
+ DRBG_PREFIX0 = 0x00,
+ DRBG_PREFIX1,
+ DRBG_PREFIX2,
+ DRBG_PREFIX3
+};
+
+#endif /* _DRBG_H */