chromium/third_party/boringssl/src/crypto/rand_extra/urandom.c

/* Copyright (c) 2014, Google Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

#if !defined(_GNU_SOURCE)
#define _GNU_SOURCE …
#endif

#include <openssl/rand.h>

#include "../bcm_support.h"
#include "sysrand_internal.h"

#if defined(OPENSSL_RAND_URANDOM)

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#if defined(OPENSSL_LINUX)
#if defined(BORINGSSL_FIPS)
#include <linux/random.h>
#include <sys/ioctl.h>
#endif
#include <sys/syscall.h>

#if defined(OPENSSL_ANDROID)
#include <sys/system_properties.h>
#endif

#if !defined(OPENSSL_ANDROID)
#define OPENSSL_HAS_GETAUXVAL
#endif
// glibc prior to 2.16 does not have getauxval and sys/auxv.h. Android has some
// host builds (i.e. not building for Android itself, so |OPENSSL_ANDROID| is
// unset) which are still using a 2.15 sysroot.
//
// TODO(davidben): Remove this once Android updates their sysroot.
#if defined(__GLIBC_PREREQ)
#if !__GLIBC_PREREQ(2, 16)
#undef OPENSSL_HAS_GETAUXVAL
#endif
#endif
#if defined(OPENSSL_HAS_GETAUXVAL)
#include <sys/auxv.h>
#endif
#endif  // OPENSSL_LINUX

#include <openssl/thread.h>
#include <openssl/mem.h>

#include "getrandom_fillin.h"
#include "../internal.h"


#if defined(USE_NR_getrandom)

#if defined(OPENSSL_MSAN)
void __msan_unpoison(void *, size_t);
#endif

static ssize_t boringssl_getrandom(void *buf, size_t buf_len, unsigned flags) { … }

#endif  // USE_NR_getrandom

// kHaveGetrandom in |urandom_fd| signals that |getrandom| or |getentropy| is
// available and should be used instead.
static const int kHaveGetrandom = …;

// urandom_fd is a file descriptor to /dev/urandom. It's protected by |once|.
static int urandom_fd;

#if defined(USE_NR_getrandom)

// getrandom_ready is one if |getrandom| had been initialized by the time
// |init_once| was called and zero otherwise.
static int getrandom_ready;

// extra_getrandom_flags_for_seed contains a value that is ORed into the flags
// for getrandom() when reading entropy for a seed.
static int extra_getrandom_flags_for_seed;

// On Android, check a system property to decide whether to set
// |extra_getrandom_flags_for_seed| otherwise they will default to zero.  If
// ro.oem_boringcrypto_hwrand is true then |extra_getrandom_flags_for_seed| will
// be set to GRND_RANDOM, causing all random data to be drawn from the same
// source as /dev/random.
static void maybe_set_extra_getrandom_flags(void) { … }

#endif  // USE_NR_getrandom

static CRYPTO_once_t rand_once = …;

// init_once initializes the state of this module to values previously
// requested. This is the only function that modifies |urandom_fd|, which may be
// read safely after calling the once.
static void init_once(void) { … }

static CRYPTO_once_t wait_for_entropy_once = …;

static void wait_for_entropy(void) { … }

// fill_with_entropy writes |len| bytes of entropy into |out|. It returns one
// on success and zero on error. If |block| is one, this function will block
// until the entropy pool is initialized. Otherwise, this function may fail,
// setting |errno| to |EAGAIN| if the entropy pool has not yet been initialized.
// If |seed| is one, this function will OR in the value of
// |*extra_getrandom_flags_for_seed()| when using |getrandom|.
static int fill_with_entropy(uint8_t *out, size_t len, int block, int seed) { … }

void CRYPTO_init_sysrand(void) { … }

// CRYPTO_sysrand puts |requested| random bytes into |out|.
void CRYPTO_sysrand(uint8_t *out, size_t requested) { … }

void CRYPTO_sysrand_for_seed(uint8_t *out, size_t requested) { … }

int CRYPTO_sysrand_if_available(uint8_t *out, size_t requested) { … }

#endif  // OPENSSL_RAND_URANDOM