92f888e836
Fork-unsafe buffering was a mode that could be enabled by applications that were sure that they didn't need to worry about state duplication. It saved reads to urandom. Since everything is now going through the CTR-DRBG, we can get the same effect by simply not reading additional data from urandom in this case. This change drops the buffering from urandom.c and, instead, implements fork-unsafe buffering as a mode that skips reading additional data from urandom, which only happened when RDRAND wasn't available anyway. Since we expect the power-on self-tests to call into the PRNG, this change also makes the flag capable of changing at any point by using a mutex rather than a once. This is split into a separate file so that it doesn't have to go into the FIPS module—since it uses r/w data that would be a pain. Change-Id: I5fd0ead0422e770e35758f080bb1cffa70d0c8da Reviewed-on: https://boringssl-review.googlesource.com/14924 Reviewed-by: Adam Langley <agl@google.com>
93 lines
3.6 KiB
C
93 lines
3.6 KiB
C
/* Copyright (c) 2015, Google Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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#ifndef OPENSSL_HEADER_CRYPTO_RAND_INTERNAL_H
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#define OPENSSL_HEADER_CRYPTO_RAND_INTERNAL_H
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#include <openssl/aes.h>
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#include "../internal.h"
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#include "../modes/internal.h"
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#if defined(__cplusplus)
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extern "C" {
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#endif
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/* RAND_bytes_with_additional_data samples from the RNG after mixing 32 bytes
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* from |user_additional_data| in. */
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void RAND_bytes_with_additional_data(uint8_t *out, size_t out_len,
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const uint8_t user_additional_data[32]);
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/* CRYPTO_sysrand fills |len| bytes at |buf| with entropy from the operating
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* system. */
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void CRYPTO_sysrand(uint8_t *buf, size_t len);
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/* rand_fork_unsafe_buffering_enabled returns whether fork-unsafe buffering has
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* been enabled via |RAND_enable_fork_unsafe_buffering|. */
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int rand_fork_unsafe_buffering_enabled(void);
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/* CTR_DRBG_STATE contains the state of a CTR_DRBG based on AES-256. See SP
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* 800-90Ar1. */
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typedef struct {
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alignas(16) AES_KEY ks;
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block128_f block;
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ctr128_f ctr;
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union {
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uint8_t bytes[16];
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uint32_t words[4];
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} counter;
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uint64_t reseed_counter;
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} CTR_DRBG_STATE;
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/* See SP 800-90Ar1, table 3. */
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#define CTR_DRBG_ENTROPY_LEN 48
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#define CTR_DRBG_MAX_GENERATE_LENGTH 65536
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/* CTR_DRBG_init initialises |*drbg| given |CTR_DRBG_ENTROPY_LEN| bytes of
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* entropy in |entropy| and, optionally, a personalization string up to
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* |CTR_DRBG_ENTROPY_LEN| bytes in length. It returns one on success and zero
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* on error. */
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OPENSSL_EXPORT int CTR_DRBG_init(CTR_DRBG_STATE *drbg,
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const uint8_t entropy[CTR_DRBG_ENTROPY_LEN],
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const uint8_t *personalization,
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size_t personalization_len);
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/* CTR_DRBG_reseed reseeds |drbg| given |CTR_DRBG_ENTROPY_LEN| bytes of entropy
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* in |entropy| and, optionally, up to |CTR_DRBG_ENTROPY_LEN| bytes of
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* additional data. It returns one on success or zero on error. */
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OPENSSL_EXPORT int CTR_DRBG_reseed(CTR_DRBG_STATE *drbg,
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const uint8_t entropy[CTR_DRBG_ENTROPY_LEN],
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const uint8_t *additional_data,
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size_t additional_data_len);
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/* CTR_DRBG_generate processes to up |CTR_DRBG_ENTROPY_LEN| bytes of additional
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* data (if any) and then writes |out_len| random bytes to |out|, where
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* |out_len| <= |CTR_DRBG_MAX_GENERATE_LENGTH|. It returns one on success or
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* zero on error. */
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OPENSSL_EXPORT int CTR_DRBG_generate(CTR_DRBG_STATE *drbg, uint8_t *out,
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size_t out_len,
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const uint8_t *additional_data,
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size_t additional_data_len);
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/* CTR_DRBG_clear zeroises the state of |drbg|. */
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OPENSSL_EXPORT void CTR_DRBG_clear(CTR_DRBG_STATE *drbg);
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#if defined(__cplusplus)
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} /* extern C */
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#endif
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#endif /* OPENSSL_HEADER_CRYPTO_RAND_INTERNAL_H */
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