8d55d1872a
This patch adds support to load BTI-enabled objects.
According to the ABI, BTI is recorded in the .note.gnu.property section.
The new parser evaluates the property section, if exists.
It searches for .note section with NT_GNU_PROPERTY_TYPE_0.
Once found it tries to find GNU_PROPERTY_AARCH64_FEATURE_1_AND.
The results are cached.
The main change in linker is when protection of loaded ranges gets
applied. When BTI is requested and the platform also supports it
the prot flags have to be amended with PROT_BTI for executable ranges.
Failing to add PROT_BTI flag would disable BTI protection.
Moreover, adding the new PROT flag for shared objects without BTI
compatibility would break applications.
Kernel does not add PROT_BTI to a loaded ELF which has interpreter.
Linker handles this case too.
Test: 1. Flame boots
2. Tested on FVP with BTI enabled
Change-Id: Iafdf223b74c6e75d9f17ca90500e6fe42c4c1218
93 lines
3 KiB
C++
93 lines
3 KiB
C++
/*
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* Copyright (C) 2020 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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#pragma once
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#include <elf.h>
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#include <link.h>
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#include "linker_soinfo.h"
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// The Elf* structures below are derived from the document
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// Linux Extensions to gABI (https://github.com/hjl-tools/linux-abi/wiki).
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// Essentially, these types would be defined in <elf.h>, but this is not
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// the case at the moment.
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struct Elf32_Prop {
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Elf32_Word pr_type;
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Elf32_Word pr_datasz;
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char pr_data[0];
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};
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// On 32-bit machines this should be 4-byte aligned.
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struct Elf32_NhdrGNUProperty {
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Elf32_Nhdr nhdr;
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char n_name[4];
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char n_desc[0];
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};
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struct Elf64_Prop {
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Elf64_Word pr_type;
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Elf64_Word pr_datasz;
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char pr_data[0];
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};
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// On 64-bit machines this should be 8-byte aligned.
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struct Elf64_NhdrGNUProperty {
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Elf64_Nhdr nhdr;
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char n_name[4];
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char n_desc[0];
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};
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struct ElfProgramProperty {
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#if defined(__aarch64__)
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bool bti_compatible = false;
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#endif
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};
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// Representation of the .note.gnu.property section found in the segment
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// with p_type = PT_GNU_PROPERTY.
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class GnuPropertySection {
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public:
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GnuPropertySection(){};
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explicit GnuPropertySection(const soinfo* si);
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GnuPropertySection(const ElfW(Phdr)* phdr, size_t phdr_count, const ElfW(Addr) load_bias,
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const char* name);
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#if defined(__aarch64__)
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bool IsBTICompatible() const;
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#endif
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private:
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const ElfW(NhdrGNUProperty)* FindSegment(const ElfW(Phdr)* phdr, size_t phdr_count,
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const ElfW(Addr) load_bias, const char* name) const;
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bool SanityCheck(const ElfW(NhdrGNUProperty)* note_nhdr, const char* name) const;
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bool Parse(const ElfW(NhdrGNUProperty)* note_nhdr, const char* name);
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ElfProgramProperty properties_ __unused;
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};
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