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
435 lines
14 KiB
C++
435 lines
14 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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#include <stdlib.h>
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#include <iostream>
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#include <sstream>
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#include <string>
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#include <gtest/gtest.h>
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#include "linker.h"
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#include "linker_globals.h"
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#include "linker_note_gnu_property.h"
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#include "platform/bionic/macros.h"
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#define SONAME "test_so"
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static char error_buffer[1024];
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char* linker_get_error_buffer() {
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return error_buffer;
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}
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size_t linker_get_error_buffer_size() {
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return std::size(error_buffer);
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}
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static void reset_error_buffer() {
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error_buffer[0] = '\0';
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}
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platform_properties g_platform_properties {
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#if defined(__aarch64__)
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// Assume "hardware" supports Armv8.5-A BTI.
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.bti_supported = true
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#endif
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};
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// Helper macro to make the test cleaner.
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#define PHDR_WITH_NOTE_GNU_PROPERTY(__prop) \
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reset_error_buffer(); \
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ElfW(Phdr) phdrs[] = { \
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{.p_type = PT_LOAD}, \
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{ \
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.p_type = PT_GNU_PROPERTY, \
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.p_vaddr = reinterpret_cast<ElfW(Addr)>(__prop), \
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.p_memsz = sizeof(ElfW(NhdrGNUProperty)) + (__prop)->nhdr.n_descsz, \
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}, \
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{.p_type = PT_NULL}, \
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}; \
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auto note = GnuPropertySection(&phdrs[0], std::size(phdrs), 0, SONAME)
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// Helper to check for no error message.
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#define ASSERT_NO_ERROR_MSG() ASSERT_STREQ(error_buffer, "")
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// Helper to check expected error message.
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#define ASSERT_ERROR_MSG_EQ(__expected) ASSERT_STREQ(error_buffer, "\"" SONAME "\" " __expected)
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static void test_bti_not_supported(GnuPropertySection& note __unused) {
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#if defined(__aarch64__)
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ASSERT_FALSE(note.IsBTICompatible());
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#endif
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}
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#if defined(__aarch64__)
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static void test_bti_supported(GnuPropertySection& note __unused) {
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ASSERT_TRUE(note.IsBTICompatible());
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}
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#endif
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// Helper class to build a well-formed .note.gnu.property section.
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class GnuPropertySectionBuilder {
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public:
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GnuPropertySectionBuilder() {
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note = reinterpret_cast<ElfW(NhdrGNUProperty)*>(§ion[0]);
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note->nhdr.n_namesz = 4;
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note->nhdr.n_descsz = 0;
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note->nhdr.n_type = NT_GNU_PROPERTY_TYPE_0;
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memcpy(note->n_name, "GNU", 4);
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}
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template <typename T>
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bool push(ElfW(Word) pr_type, ElfW(Word) pr_datasz, const T* pr_data) {
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// Must be aligned.
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const uintptr_t addition = align_up(pr_datasz, sizeof(ElfW(Addr)));
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if ((offset() + addition) > kMaxSectionSize) {
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return false;
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}
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++entries;
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ElfW(Prop)* prop = reinterpret_cast<ElfW(Prop)*>(§ion[offset()]);
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// Header
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prop->pr_type = pr_type;
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prop->pr_datasz = pr_datasz;
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step(2 * sizeof(ElfW(Word)));
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// Data
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memcpy(§ion[offset()], reinterpret_cast<const void*>(pr_data), pr_datasz);
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step(pr_datasz);
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// Padding
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memset(§ion[offset()], 0xAA, addition - pr_datasz);
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step(addition - pr_datasz);
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return true;
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}
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ElfW(NhdrGNUProperty)* data() const { return note; }
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void dump() const {
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std::cout << ".note.gnu.property\n";
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dump_member("n_namesz", note->nhdr.n_namesz);
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dump_member("n_descsz", note->nhdr.n_descsz);
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dump_member("n_type ", note->nhdr.n_type);
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dump_member("n_name ", note->n_name);
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dump_member("entries ", entries);
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if (entries > 0) {
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std::cout << " raw data:";
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const uintptr_t offset = note->nhdr.n_descsz + 16;
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for (uintptr_t offs = 16; offs < offset; ++offs) {
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std::cout << std::hex;
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if ((offs % 8) == 0) {
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std::cout << "\n ";
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}
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auto value = static_cast<unsigned>(section[offs]);
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std::cout << " ";
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if (value < 0x10) {
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std::cout << "0";
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}
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std::cout << static_cast<unsigned>(section[offs]);
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}
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std::cout << std::dec << "\n";
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}
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}
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void corrupt_n_descsz(ElfW(Word) n_descsz) { note->nhdr.n_descsz = n_descsz; }
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private:
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template <typename T>
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void dump_member(const char* name, T value) const {
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std::cout << " " << name << " " << value << "\n";
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}
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ElfW(Word) offset() const { return note->nhdr.n_descsz + 16; }
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template <typename T>
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void step(T value) {
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note->nhdr.n_descsz += static_cast<ElfW(Word)>(value);
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}
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static const size_t kMaxSectionSize = 1024;
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alignas(8) uint8_t section[kMaxSectionSize];
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ElfW(NhdrGNUProperty)* note;
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size_t entries = 0;
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};
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// Tests that the default constructed instance does not report support
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// for Armv8.5-A BTI.
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TEST(note_gnu_property, default) {
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GnuPropertySection note;
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test_bti_not_supported(note);
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ASSERT_NO_ERROR_MSG();
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}
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// Tests that an instance without valid phdr pointer does not report
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// support for Armv8.5-A BTI.
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TEST(note_gnu_property, phdr_null) {
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auto note = GnuPropertySection(nullptr, 0, 0, SONAME);
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test_bti_not_supported(note);
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ASSERT_NO_ERROR_MSG();
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}
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// Tests that an instance without finding PT_GNU_PROPERTY does not
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// report support for Armv8.5-A BTI.
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TEST(note_gnu_property, no_pt_gnu_property) {
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ElfW(Phdr) phdrs[] = {
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{.p_type = PT_LOAD},
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{.p_type = PT_NULL},
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};
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reset_error_buffer();
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auto note = GnuPropertySection(&phdrs[0], std::size(phdrs), 0, SONAME);
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test_bti_not_supported(note);
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ASSERT_NO_ERROR_MSG();
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}
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// Tests the validity check for invalid PT_GNU_PROPERTY size.
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TEST(note_gnu_property, pt_gnu_property_bad_size) {
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ElfW(Phdr) phdrs[] = {
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{.p_type = PT_LOAD},
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{
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.p_type = PT_GNU_PROPERTY,
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.p_vaddr = 0,
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.p_memsz = sizeof(ElfW(NhdrGNUProperty)) - 1, // Invalid
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},
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{.p_type = PT_NULL},
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};
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reset_error_buffer();
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auto note = GnuPropertySection(&phdrs[0], std::size(phdrs), 0, SONAME);
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test_bti_not_supported(note);
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ASSERT_ERROR_MSG_EQ("PT_GNU_PROPERTY segment is too small. Segment size is 15, minimum is 16.");
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}
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// Tests that advertised n_descsz should still fit into p_memsz.
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TEST(note_gnu_property, pt_gnu_property_too_small) {
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ElfW(NhdrGNUProperty) prop = {
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.nhdr = {.n_namesz = PT_GNU_PROPERTY, .n_descsz = 1, .n_type = NT_GNU_PROPERTY_TYPE_0},
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.n_name = "GNU",
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};
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ElfW(Phdr) phdrs[] = {
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{
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.p_type = PT_GNU_PROPERTY,
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.p_vaddr = reinterpret_cast<ElfW(Addr)>(&prop),
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.p_memsz = sizeof(ElfW(NhdrGNUProperty)), // Off by one
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},
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};
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reset_error_buffer();
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auto note = GnuPropertySection(&phdrs[0], std::size(phdrs), 0, SONAME);
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test_bti_not_supported(note);
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ASSERT_ERROR_MSG_EQ("PT_GNU_PROPERTY segment p_memsz (16) is too small for note n_descsz (1).");
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}
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// Tests the validity check for invalid .note.gnu.property type.
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TEST(note_gnu_property, pt_gnu_property_bad_type) {
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ElfW(NhdrGNUProperty) prop = {
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.nhdr =
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{
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.n_namesz = 4,
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.n_descsz = 0,
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.n_type = NT_GNU_PROPERTY_TYPE_0 - 1 // Invalid
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},
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.n_name = "GNU",
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};
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PHDR_WITH_NOTE_GNU_PROPERTY(&prop);
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test_bti_not_supported(note);
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ASSERT_ERROR_MSG_EQ(".note.gnu.property: unexpected note type. Expected 5, got 4.");
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}
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// Tests the validity check for invalid .note.gnu.property name size.
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TEST(note_gnu_property, pt_gnu_property_bad_namesz) {
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ElfW(NhdrGNUProperty) prop = {
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.nhdr = {.n_namesz = 3, // Invalid
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.n_descsz = 0,
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.n_type = NT_GNU_PROPERTY_TYPE_0},
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.n_name = "GNU",
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};
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PHDR_WITH_NOTE_GNU_PROPERTY(&prop);
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test_bti_not_supported(note);
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ASSERT_ERROR_MSG_EQ(".note.gnu.property: unexpected name size. Expected 4, got 3.");
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}
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// Tests the validity check for invalid .note.gnu.property name.
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TEST(note_gnu_property, pt_gnu_property_bad_name) {
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ElfW(NhdrGNUProperty) prop = {
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.nhdr = {.n_namesz = 4, .n_descsz = 0, .n_type = NT_GNU_PROPERTY_TYPE_0},
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.n_name = "ABC", // Invalid
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};
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PHDR_WITH_NOTE_GNU_PROPERTY(&prop);
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test_bti_not_supported(note);
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ASSERT_ERROR_MSG_EQ(".note.gnu.property: unexpected name. Expected 'GNU', got 'ABC'.");
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}
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// Tests the validity check for not enough space for a Program Property header.
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TEST(note_gnu_property, pt_gnu_property_pphdr_no_space) {
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ElfW(NhdrGNUProperty) prop = {
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.nhdr = {.n_namesz = 4,
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.n_descsz = 7, // Invalid
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.n_type = NT_GNU_PROPERTY_TYPE_0},
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.n_name = "GNU",
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};
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PHDR_WITH_NOTE_GNU_PROPERTY(&prop);
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test_bti_not_supported(note);
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ASSERT_ERROR_MSG_EQ(".note.gnu.property: no more space left for a Program Property Note header.");
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}
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// Tests an empty .note.gnu.property.
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TEST(note_gnu_property, pt_gnu_property_no_data) {
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GnuPropertySectionBuilder prop;
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PHDR_WITH_NOTE_GNU_PROPERTY(prop.data());
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test_bti_not_supported(note);
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ASSERT_NO_ERROR_MSG();
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}
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// Tests a .note.gnu.property section with elements with pr_datasz = 0.
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TEST(note_gnu_property, pt_gnu_property_no_prop) {
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GnuPropertySectionBuilder prop;
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ASSERT_TRUE(prop.push(1, 0, (void*)nullptr));
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ASSERT_TRUE(prop.push(2, 0, (void*)nullptr));
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ASSERT_TRUE(prop.push(3, 0, (void*)nullptr));
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PHDR_WITH_NOTE_GNU_PROPERTY(prop.data());
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test_bti_not_supported(note);
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ASSERT_NO_ERROR_MSG();
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}
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// Tests that GNU_PROPERTY_AARCH64_FEATURE_1_AND must have pr_datasz = 4.
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TEST(note_gnu_property, pt_gnu_property_bad_pr_datasz) {
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#if defined(__aarch64__)
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GnuPropertySectionBuilder prop;
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ElfW(Word) pr_data[] = {GNU_PROPERTY_AARCH64_FEATURE_1_BTI, 0, 0};
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ASSERT_TRUE(prop.push(GNU_PROPERTY_AARCH64_FEATURE_1_AND, 12, &pr_data));
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PHDR_WITH_NOTE_GNU_PROPERTY(prop.data());
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test_bti_not_supported(note);
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ASSERT_ERROR_MSG_EQ(
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".note.gnu.property: property descriptor size is invalid. Expected 4 bytes for "
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"GNU_PROPERTY_AARCH64_FEATURE_1_AND, got 12.");
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#else
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GTEST_SKIP() << "BTI is not supported on this architecture.";
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#endif
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}
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// Tests a .note.gnu.property section with only GNU_PROPERTY_AARCH64_FEATURE_1_BTI property array.
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TEST(note_gnu_property, pt_gnu_property_ok_1) {
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#if defined(__aarch64__)
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GnuPropertySectionBuilder prop;
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ElfW(Word) pr_data[] = {GNU_PROPERTY_AARCH64_FEATURE_1_BTI};
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ASSERT_TRUE(prop.push(GNU_PROPERTY_AARCH64_FEATURE_1_AND, sizeof(pr_data), &pr_data));
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PHDR_WITH_NOTE_GNU_PROPERTY(prop.data());
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ASSERT_NO_ERROR_MSG();
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test_bti_supported(note);
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#else
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GTEST_SKIP() << "BTI is not supported on this architecture.";
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#endif
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}
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// Tests a .note.gnu.property section with only GNU_PROPERTY_AARCH64_FEATURE_1_BTI property array.
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TEST(note_gnu_property, pt_gnu_property_ok_2) {
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#if defined(__aarch64__)
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GnuPropertySectionBuilder prop;
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ElfW(Word) pr_data[] = {static_cast<ElfW(Word)>(~GNU_PROPERTY_AARCH64_FEATURE_1_BTI)};
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ASSERT_TRUE(prop.push(GNU_PROPERTY_AARCH64_FEATURE_1_AND, sizeof(pr_data), &pr_data));
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PHDR_WITH_NOTE_GNU_PROPERTY(prop.data());
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ASSERT_NO_ERROR_MSG();
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test_bti_not_supported(note);
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#else
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GTEST_SKIP() << "BTI is not supported on this architecture.";
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#endif
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}
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// Tests a .note.gnu.property section with more property arrays.
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TEST(note_gnu_property, pt_gnu_property_ok_3) {
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#if defined(__aarch64__)
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GnuPropertySectionBuilder prop;
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ElfW(Word) pr_data_0[8] = {0xCD};
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ASSERT_TRUE(prop.push(1, 4, &pr_data_0));
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ASSERT_TRUE(prop.push(2, 3, &pr_data_0));
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ASSERT_TRUE(prop.push(3, 8, &pr_data_0));
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ElfW(Word) pr_data[] = {GNU_PROPERTY_AARCH64_FEATURE_1_BTI};
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ASSERT_TRUE(prop.push(GNU_PROPERTY_AARCH64_FEATURE_1_AND, sizeof(pr_data), &pr_data));
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ASSERT_TRUE(prop.push(4, 1, &pr_data_0));
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PHDR_WITH_NOTE_GNU_PROPERTY(prop.data());
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ASSERT_NO_ERROR_MSG();
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test_bti_supported(note);
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#else
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GTEST_SKIP() << "BTI is not supported on this architecture.";
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#endif
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}
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// Tests a .note.gnu.property but with bad property descriptor size.
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TEST(note_gnu_property, pt_gnu_property_bad_n_descsz) {
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#if defined(__aarch64__)
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GnuPropertySectionBuilder prop;
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ElfW(Word) pr_data[] = {GNU_PROPERTY_AARCH64_FEATURE_1_BTI};
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ASSERT_TRUE(prop.push(GNU_PROPERTY_AARCH64_FEATURE_1_AND, sizeof(pr_data), &pr_data));
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ElfW(Word) n_descsz;
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if (sizeof(ElfW(Addr)) == 4) {
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n_descsz = 11;
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} else {
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n_descsz = 15;
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}
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prop.corrupt_n_descsz(n_descsz);
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PHDR_WITH_NOTE_GNU_PROPERTY(prop.data());
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if (sizeof(ElfW(Addr)) == 4) {
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ASSERT_ERROR_MSG_EQ(
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".note.gnu.property: property descriptor size is invalid. Expected at least 12 bytes, got "
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"11.");
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} else {
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ASSERT_ERROR_MSG_EQ(
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".note.gnu.property: property descriptor size is invalid. Expected at least 16 bytes, got "
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"15.");
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}
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test_bti_not_supported(note);
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#else
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GTEST_SKIP() << "BTI is not supported on this architecture.";
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#endif
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}
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// Tests if platform support is missing.
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TEST(note_gnu_property, no_platform_support) {
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#if defined(__aarch64__)
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auto bti_supported_orig = g_platform_properties.bti_supported;
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g_platform_properties.bti_supported = false;
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GnuPropertySectionBuilder prop;
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ElfW(Word) pr_data[] = {GNU_PROPERTY_AARCH64_FEATURE_1_BTI};
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ASSERT_TRUE(prop.push(GNU_PROPERTY_AARCH64_FEATURE_1_AND, sizeof(pr_data), &pr_data));
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PHDR_WITH_NOTE_GNU_PROPERTY(prop.data());
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ASSERT_NO_ERROR_MSG();
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test_bti_not_supported(note);
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g_platform_properties.bti_supported = bti_supported_orig;
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#else
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GTEST_SKIP() << "BTI is not supported on this architecture.";
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#endif
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}
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