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https://github.com/SerenityOS/serenity
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6b7ce19161
These instances were detected by searching for files that include stdlib.h, but don't match the regex: \\b(_abort|abort|abs|aligned_alloc|arc4random|arc4random_buf|arc4random_ uniform|atexit|atof|atoi|atol|atoll|bsearch|calloc|clearenv|div|div_t|ex it|_Exit|EXIT_FAILURE|EXIT_SUCCESS|free|getenv|getprogname|grantpt|labs| ldiv|ldiv_t|llabs|lldiv|lldiv_t|malloc|malloc_good_size|malloc_size|mble n|mbstowcs|mbtowc|mkdtemp|mkstemp|mkstemps|mktemp|posix_memalign|posix_o penpt|ptsname|ptsname_r|putenv|qsort|qsort_r|rand|RAND_MAX|random|reallo c|realpath|secure_getenv|serenity_dump_malloc_stats|serenity_setenv|sete nv|setprogname|srand|srandom|strtod|strtof|strtol|strtold|strtoll|strtou l|strtoull|system|unlockpt|unsetenv|wcstombs|wctomb)\\b (Without the linebreaks.) This regex is pessimistic, so there might be more files that don't actually use anything from the stdlib. In theory, one might use LibCPP to detect things like this automatically, but let's do this one step after another.
82 lines
1.9 KiB
C++
82 lines
1.9 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2021-2022, Brian Gianforcaro <bgianf@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Types.h>
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#if defined(KERNEL)
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# include <Kernel/StdLib.h>
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#else
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# include <string.h>
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#endif
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ALWAYS_INLINE void fast_u32_copy(u32* dest, u32 const* src, size_t count)
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{
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#if ARCH(X86_64)
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asm volatile(
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"rep movsl\n"
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: "+S"(src), "+D"(dest), "+c"(count)::"memory");
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#else
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__builtin_memcpy(dest, src, count * 4);
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#endif
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}
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ALWAYS_INLINE void fast_u32_fill(u32* dest, u32 value, size_t count)
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{
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#if ARCH(X86_64)
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asm volatile(
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"rep stosl\n"
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: "=D"(dest), "=c"(count)
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: "D"(dest), "c"(count), "a"(value)
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: "memory");
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#else
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for (auto* p = dest; p < (dest + count); ++p) {
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*p = value;
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}
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#endif
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}
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namespace AK {
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inline void secure_zero(void* ptr, size_t size)
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{
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__builtin_memset(ptr, 0, size);
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// The memory barrier is here to avoid the compiler optimizing
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// away the memset when we rely on it for wiping secrets.
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asm volatile("" ::
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: "memory");
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}
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// Naive implementation of a constant time buffer comparison function.
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// The goal being to not use any conditional branching so calls are
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// guarded against potential timing attacks.
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//
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// See OpenBSD's timingsafe_memcmp for more advanced implementations.
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inline bool timing_safe_compare(void const* b1, void const* b2, size_t len)
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{
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auto* c1 = static_cast<char const*>(b1);
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auto* c2 = static_cast<char const*>(b2);
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u8 res = 0;
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for (size_t i = 0; i < len; i++) {
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res |= c1[i] ^ c2[i];
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}
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// FIXME: !res can potentially inject branches depending
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// on which toolchain is being used for compilation. Ideally
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// we would use a more advanced algorithm.
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return !res;
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}
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}
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#if USING_AK_GLOBALLY
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using AK::secure_zero;
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using AK::timing_safe_compare;
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#endif
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