6574918875
In order to add Control-flow Enforcement Technology (CET) Shadow Stack (SHSTK) support, we need to parse the `PT_GNU_PROPERTY` program header and the corresponding section to evaluate if the binary being started was compiled with the necessary support. PS: This is my first PR to llvm-libc, I might have made obvious styling mistakes so I'd appreciate any feedback or suggestions to improve it. I have a prototype branch using this change to enable SHSTK support: https://github.com/jakos-sec/llvm-project/tree/add-shstk-support
46 lines
1.6 KiB
C++
46 lines
1.6 KiB
C++
//===-- Header file of gnu_property_section -------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_STARTUP_LINUX_GNU_PROPERTY_SECTION_H
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#define LLVM_LIBC_STARTUP_LINUX_GNU_PROPERTY_SECTION_H
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#include "hdr/elf_proxy.h"
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#include "hdr/link_macros.h"
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#include "src/__support/macros/attributes.h"
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#include "src/__support/macros/config.h"
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namespace LIBC_NAMESPACE_DECL {
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struct GnuPropertyFeatures {
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// Set if the binary was compiled with SHSTK enabled and declares support.
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bool shstk_supported = false;
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};
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// This class parses the .note.gnu.property section within the ELF binary.
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// Currently it only extracts the bit representing SHSTK support but can easily
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// be expanded to other features included in it.
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// The layout of the .note.gnu.property section and the program property is
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// described in "System V Application Binary Interface - Linux Extensions"
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// (https://github.com/hjl-tools/linux-abi/wiki).
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class GnuPropertySection {
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private:
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[[maybe_unused]] GnuPropertyFeatures features_;
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public:
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LIBC_INLINE GnuPropertySection() = default;
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bool parse(const ElfW(Phdr) * gnu_property_phdr, const ElfW(Addr) base);
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LIBC_INLINE bool is_shstk_supported() const {
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return features_.shstk_supported;
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}
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};
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} // namespace LIBC_NAMESPACE_DECL
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#endif // LLVM_LIBC_STARTUP_LINUX_GNU_PROPERTY_SECTION_H
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