c11fb66739
The name is misleading anyway. Bug: http://b/67015565 Test: boots Change-Id: Ic765e376d84e1ca474d3324eab32e14ea1ae9712
59 lines
2.3 KiB
C++
59 lines
2.3 KiB
C++
/*
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* Copyright (C) 2016 The Android Open Source Project
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* All rights reserved.
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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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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "private/bionic_arc4random.h"
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#include <stdlib.h>
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#include <string.h>
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#include <sys/auxv.h>
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#include <unistd.h>
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#include <async_safe/log.h>
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#include "private/KernelArgumentBlock.h"
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void __libc_safe_arc4random_buf(void* buf, size_t n, KernelArgumentBlock& args) {
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// Only call arc4random_buf once we have `/dev/urandom` because getentropy(3)
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// will fall back to using `/dev/urandom` if getrandom(2) fails, and abort if
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// if can't use `/dev/urandom`.
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static bool have_urandom = access("/dev/urandom", R_OK) == 0;
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if (have_urandom) {
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arc4random_buf(buf, n);
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return;
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}
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static size_t at_random_bytes_consumed = 0;
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if (at_random_bytes_consumed + n > 16) {
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async_safe_fatal("ran out of AT_RANDOM bytes, have %zu, requested %zu",
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16 - at_random_bytes_consumed, n);
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}
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memcpy(buf, reinterpret_cast<char*>(args.getauxval(AT_RANDOM)) + at_random_bytes_consumed, n);
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at_random_bytes_consumed += n;
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return;
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}
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