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c9a6bcf81d
Kernel provided it for about 4 years at this point. I think it is about time to finally use it in userspace.
61 lines
1.5 KiB
C++
61 lines
1.5 KiB
C++
/*
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* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Types.h>
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#include <assert.h>
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#include <errno.h>
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#include <sys/auxv.h>
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#include <sys/internals.h>
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#include <unistd.h>
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[[gnu::weak]] char** __environ_value() asm("__environ_value");
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extern "C" {
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#ifdef NO_TLS
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int errno_storage;
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#else
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__thread int errno_storage;
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#endif
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bool __environ_is_malloced = false;
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bool __stdio_is_initialized = false;
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void* __auxiliary_vector = reinterpret_cast<void*>(explode_byte(0xe1));
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#ifndef _DYNAMIC_LOADER
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char** environ = reinterpret_cast<char**>(explode_byte(0xe2));
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uintptr_t __stack_chk_guard;
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#endif
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int* __errno_location()
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{
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return &errno_storage;
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}
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void __libc_init()
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{
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#ifndef _DYNAMIC_LOADER
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// We can only call magic functions until __stack_chk_guard is initialized.
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environ = __environ_value();
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#endif
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char** env;
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for (env = environ; *env; ++env)
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;
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__auxiliary_vector = (void*)++env;
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#ifndef _DYNAMIC_LOADER
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for (auxv_t* entry = reinterpret_cast<auxv_t*>(__auxiliary_vector); entry->a_type != AT_NULL; ++entry)
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if (entry->a_type == AT_RANDOM)
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__stack_chk_guard = *(reinterpret_cast<u64*>(entry->a_un.a_ptr) + 1);
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// We include an additional hardening: zero the first byte of the stack guard to avoid leaking
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// or overwriting the stack guard with C-style string functions.
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__stack_chk_guard &= ~0xffULL;
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#endif
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__malloc_init();
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__stdio_init();
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}
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}
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