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Revert "Extract LC_CODE_SIGNATURE related implementation out of LLD" 

This reverts commit cc8229603b.

As discussed in the review of https://reviews.llvm.org/D109972, this was not
right approach, so we are reverting to start with a different approach.

Differential Revision: https://reviews.llvm.org/D110974
This commit is contained in:
Daniel Rodríguez Troitiño 2021-10-01 14:30:21 -07:00
parent 91dfc0840d
commit 657f02d458
5 changed files with 97 additions and 198 deletions
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96
lld/MachO/SyntheticSections.cpp
View File

@ -24,6 +24,11 @@
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SHA256.h"
#if defined(__APPLE__)
#include <sys/mman.h>
#endif
#ifdef LLVM_HAVE_LIBXAR
#include <fcntl.h>
@ -1146,30 +1151,97 @@ void StringTableSection::writeTo(uint8_t *buf) const {
}
}
static_assert((CodeSignatureSection::blobHeadersSize % 8) == 0, "");
static_assert((CodeSignatureSection::fixedHeadersSize % 8) == 0, "");
CodeSignatureSection::CodeSignatureSection()
: LinkEditSection(segment_names::linkEdit, section_names::codeSignature) {
align = object::CodeSignatureSection::Align; // required by libstuff
align = 16; // required by libstuff
// FIXME: Consider using finalOutput instead of outputFile.
fileName = config->outputFile;
size_t slashIndex = fileName.rfind("/");
if (slashIndex != std::string::npos)
fileName = fileName.drop_front(slashIndex + 1);
allHeadersSize = alignTo<16>(fixedHeadersSize + fileName.size() + 1);
fileNamePad = allHeadersSize - fixedHeadersSize - fileName.size();
}
uint32_t CodeSignatureSection::getBlockCount() const {
return (fileOff + blockSize - 1) / blockSize;
}
uint64_t CodeSignatureSection::getRawSize() const {
return static_cast<uint64_t>(sectionBuilder->getRawSize());
return allHeadersSize + getBlockCount() * hashSize;
}
void CodeSignatureSection::writeHashes(uint8_t *buf) const {
sectionBuilder->write(buf);
uint8_t *code = buf;
uint8_t *codeEnd = buf + fileOff;
uint8_t *hashes = codeEnd + allHeadersSize;
while (code < codeEnd) {
StringRef block(reinterpret_cast<char *>(code),
std::min(codeEnd - code, static_cast<ssize_t>(blockSize)));
SHA256 hasher;
hasher.update(block);
StringRef hash = hasher.final();
assert(hash.size() == hashSize);
memcpy(hashes, hash.data(), hashSize);
code += blockSize;
hashes += hashSize;
}
#if defined(__APPLE__)
// This is macOS-specific work-around and makes no sense for any
// other host OS. See https://openradar.appspot.com/FB8914231
//
// The macOS kernel maintains a signature-verification cache to
// quickly validate applications at time of execve(2). The trouble
// is that for the kernel creates the cache entry at the time of the
// mmap(2) call, before we have a chance to write either the code to
// sign or the signature header+hashes. The fix is to invalidate
// all cached data associated with the output file, thus discarding
// the bogus prematurely-cached signature.
msync(buf, fileOff + getSize(), MS_INVALIDATE);
#endif
}
void CodeSignatureSection::writeTo(uint8_t *buf) const {
// The entire code section including header is written
// in CodeSignatureSection::writeHashes above.
}
void CodeSignatureSection::finalize() {
uint32_t signatureSize = static_cast<uint32_t>(getSize());
auto *superBlob = reinterpret_cast<CS_SuperBlob *>(buf);
write32be(&superBlob->magic, CSMAGIC_EMBEDDED_SIGNATURE);
write32be(&superBlob->length, signatureSize);
write32be(&superBlob->count, 1);
auto *blobIndex = reinterpret_cast<CS_BlobIndex *>(&superBlob[1]);
write32be(&blobIndex->type, CSSLOT_CODEDIRECTORY);
write32be(&blobIndex->offset, blobHeadersSize);
auto *codeDirectory =
reinterpret_cast<CS_CodeDirectory *>(buf + blobHeadersSize);
write32be(&codeDirectory->magic, CSMAGIC_CODEDIRECTORY);
write32be(&codeDirectory->length, signatureSize - blobHeadersSize);
write32be(&codeDirectory->version, CS_SUPPORTSEXECSEG);
write32be(&codeDirectory->flags, CS_ADHOC | CS_LINKER_SIGNED);
write32be(&codeDirectory->hashOffset,
sizeof(CS_CodeDirectory) + fileName.size() + fileNamePad);
write32be(&codeDirectory->identOffset, sizeof(CS_CodeDirectory));
codeDirectory->nSpecialSlots = 0;
write32be(&codeDirectory->nCodeSlots, getBlockCount());
write32be(&codeDirectory->codeLimit, fileOff);
codeDirectory->hashSize = static_cast<uint8_t>(hashSize);
codeDirectory->hashType = kSecCodeSignatureHashSHA256;
codeDirectory->platform = 0;
codeDirectory->pageSize = blockSizeShift;
codeDirectory->spare2 = 0;
codeDirectory->scatterOffset = 0;
codeDirectory->teamOffset = 0;
codeDirectory->spare3 = 0;
codeDirectory->codeLimit64 = 0;
OutputSegment *textSeg = getOrCreateOutputSegment(segment_names::text);
// NOTE: ld64 seems to also use outputFile instead of finalOutput
sectionBuilder = std::make_unique<object::CodeSignatureSection>(
fileOff, config->outputFile, config->outputType, textSeg->fileOff,
textSeg->fileSize);
write64be(&codeDirectory->execSegBase, textSeg->fileOff);
write64be(&codeDirectory->execSegLimit, textSeg->fileSize);
write64be(&codeDirectory->execSegFlags,
config->outputType == MH_EXECUTE ? CS_EXECSEG_MAIN_BINARY : 0);
auto *id = reinterpret_cast<char *>(&codeDirectory[1]);
memcpy(id, fileName.begin(), fileName.size());
memset(id + fileName.size(), 0, fileNamePad);
}
BitcodeBundleSection::BitcodeBundleSection()

18
lld/MachO/SyntheticSections.h
View File

@ -21,7 +21,6 @@
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Object/MachO.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
@ -477,15 +476,24 @@ public:
// The code signature comes at the very end of the linked output file.
class CodeSignatureSection final : public LinkEditSection {
public:
static constexpr uint8_t blockSizeShift = 12;
static constexpr size_t blockSize = (1 << blockSizeShift); // 4 KiB
static constexpr size_t hashSize = 256 / 8;
static constexpr size_t blobHeadersSize = llvm::alignTo<8>(
sizeof(llvm::MachO::CS_SuperBlob) + sizeof(llvm::MachO::CS_BlobIndex));
static constexpr uint32_t fixedHeadersSize =
blobHeadersSize + sizeof(llvm::MachO::CS_CodeDirectory);
uint32_t fileNamePad = 0;
uint32_t allHeadersSize = 0;
StringRef fileName;
CodeSignatureSection();
uint64_t getRawSize() const override;
bool isNeeded() const override { return true; }
void writeTo(uint8_t *buf) const override;
uint32_t getBlockCount() const;
void writeHashes(uint8_t *buf) const;
void finalize() override;
private:
std::unique_ptr<llvm::object::CodeSignatureSection> sectionBuilder;
};
class BitcodeBundleSection final : public SyntheticSection {

38
llvm/include/llvm/Object/MachO.h
View File

@ -733,44 +733,6 @@ inline const ObjectFile *DiceRef::getObjectFile() const {
return OwningObject;
}
class CodeSignatureSection {
public:
uint32_t getRawSize() const;
uint32_t getSize() const;
static constexpr int Align = 16;
static constexpr uint8_t BlockSizeShift = 12;
static constexpr size_t BlockSize = (1 << BlockSizeShift); // 4 KiB
static constexpr size_t HashSize = 256 / 8;
static constexpr size_t BlobHeadersSize =
alignTo<8>(sizeof(MachO::CS_SuperBlob) + sizeof(MachO::CS_BlobIndex));
static constexpr uint32_t FixedHeadersSize =
BlobHeadersSize + sizeof(MachO::CS_CodeDirectory);
CodeSignatureSection(uint64_t FileOff, StringRef OutputFilePath,
MachO::HeaderFileType OutputFileType,
uint64_t TextSegmentFileOff,
uint64_t TextSegmentFileSize);
void write(uint8_t *Buf) const;
private:
uint32_t getAllHeadersSize() const;
uint32_t getBlockCount() const;
uint32_t getFileNamePad() const;
StringRef stripOutputFilePath(const StringRef OutputFilePath);
// FileOff is the offset relative to the start of the file
// used to access the start of code signature section
// in __LINKEDIT segment
uint64_t FileOff;
StringRef OutputFileName;
MachO::HeaderFileType OutputFileType;
uint64_t TextSegmentFileOff;
uint64_t TextSegmentFileSize;
};
} // end namespace object
} // end namespace llvm

1
llvm/lib/Object/CMakeLists.txt
View File

@ -2,7 +2,6 @@ add_llvm_component_library(LLVMObject
Archive.cpp
ArchiveWriter.cpp
Binary.cpp
CodeSignatureSection.cpp
COFFImportFile.cpp
COFFModuleDefinition.cpp
COFFObjectFile.cpp

142
llvm/lib/Object/CodeSignatureSection.cpp
View File

@ -1,142 +0,0 @@
//===- CodeSignatureSection.cpp - CodeSignatureSection class definition ---===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the CodeSignatureSection class
//
//===----------------------------------------------------------------------===//
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/Object/MachO.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/SHA256.h"
#include <cassert>
#if defined(__APPLE__)
#include <sys/mman.h>
#endif
using namespace llvm;
using namespace object;
using namespace support::endian;
static_assert((CodeSignatureSection::BlobHeadersSize % 8) == 0, "");
static_assert((CodeSignatureSection::FixedHeadersSize % 8) == 0, "");
CodeSignatureSection::CodeSignatureSection(uint64_t FileOff,
StringRef OutputFilePath,
MachO::HeaderFileType OutputFileType,
uint64_t TextSegmentFileOff,
uint64_t TextSegmentFileSize)
: FileOff{FileOff}, OutputFileName{stripOutputFilePath(OutputFilePath)},
OutputFileType{OutputFileType}, TextSegmentFileOff{TextSegmentFileOff},
TextSegmentFileSize{TextSegmentFileSize} {}
StringRef
CodeSignatureSection::stripOutputFilePath(const StringRef OutputFilePath) {
const size_t LastSlashIndex = OutputFilePath.rfind("/");
if (LastSlashIndex == std::string::npos)
return OutputFilePath;
return OutputFilePath.drop_front(LastSlashIndex + 1);
}
uint32_t CodeSignatureSection::getAllHeadersSize() const {
return alignTo<Align>(FixedHeadersSize + OutputFileName.size() + 1);
}
uint32_t CodeSignatureSection::getBlockCount() const {
return (FileOff + BlockSize - 1) / BlockSize;
}
uint32_t CodeSignatureSection::getFileNamePad() const {
return getAllHeadersSize() - FixedHeadersSize - OutputFileName.size();
}
uint32_t CodeSignatureSection::getRawSize() const {
return getAllHeadersSize() + getBlockCount() * HashSize;
}
uint32_t CodeSignatureSection::getSize() const {
return alignTo<Align>(getRawSize());
}
void CodeSignatureSection::write(uint8_t *Buf) const {
const uint32_t AllHeadersSize = getAllHeadersSize();
const uint32_t BlockCount = getBlockCount();
const uint32_t FileNamePad = getFileNamePad();
const uint32_t Size = getSize();
uint8_t *Code = Buf;
uint8_t *CodeEnd = Buf + FileOff;
uint8_t *Hashes = CodeEnd + AllHeadersSize;
// Write code section header.
auto *SuperBlob = reinterpret_cast<MachO::CS_SuperBlob *>(CodeEnd);
write32be(&SuperBlob->magic, MachO::CSMAGIC_EMBEDDED_SIGNATURE);
write32be(&SuperBlob->length, Size);
write32be(&SuperBlob->count, 1);
auto *BlobIndex = reinterpret_cast<MachO::CS_BlobIndex *>(&SuperBlob[1]);
write32be(&BlobIndex->type, MachO::CSSLOT_CODEDIRECTORY);
write32be(&BlobIndex->offset, BlobHeadersSize);
auto *CodeDirectory =
reinterpret_cast<MachO::CS_CodeDirectory *>(CodeEnd + BlobHeadersSize);
write32be(&CodeDirectory->magic, MachO::CSMAGIC_CODEDIRECTORY);
write32be(&CodeDirectory->length, Size - BlobHeadersSize);
write32be(&CodeDirectory->version, MachO::CS_SUPPORTSEXECSEG);
write32be(&CodeDirectory->flags, MachO::CS_ADHOC | MachO::CS_LINKER_SIGNED);
write32be(&CodeDirectory->hashOffset, sizeof(MachO::CS_CodeDirectory) +
OutputFileName.size() +
FileNamePad);
write32be(&CodeDirectory->identOffset, sizeof(MachO::CS_CodeDirectory));
CodeDirectory->nSpecialSlots = 0;
write32be(&CodeDirectory->nCodeSlots, BlockCount);
write32be(&CodeDirectory->codeLimit, FileOff);
CodeDirectory->hashSize = static_cast<uint8_t>(HashSize);
CodeDirectory->hashType = MachO::kSecCodeSignatureHashSHA256;
CodeDirectory->platform = 0;
CodeDirectory->pageSize = BlockSizeShift;
CodeDirectory->spare2 = 0;
CodeDirectory->scatterOffset = 0;
CodeDirectory->teamOffset = 0;
CodeDirectory->spare3 = 0;
CodeDirectory->codeLimit64 = 0;
write64be(&CodeDirectory->execSegBase, TextSegmentFileOff);
write64be(&CodeDirectory->execSegLimit, TextSegmentFileSize);
write64be(&CodeDirectory->execSegFlags, OutputFileType == MachO::MH_EXECUTE
? MachO::CS_EXECSEG_MAIN_BINARY
: 0);
auto *Id = reinterpret_cast<char *>(&CodeDirectory[1]);
memcpy(Id, OutputFileName.begin(), OutputFileName.size());
memset(Id + OutputFileName.size(), 0, FileNamePad);
// Write code section signature.
while (Code < CodeEnd) {
StringRef Block(reinterpret_cast<char *>(Code),
std::min(CodeEnd - Code, static_cast<ssize_t>(BlockSize)));
SHA256 Hasher;
Hasher.update(Block);
StringRef Hash = Hasher.final();
assert(Hash.size() == HashSize);
memcpy(Hashes, Hash.data(), HashSize);
Code += BlockSize;
Hashes += HashSize;
}
#if defined(__APPLE__)
// This is macOS-specific work-around and makes no sense for any
// other host OS. See https://openradar.appspot.com/FB8914231
//
// The macOS kernel maintains a signature-verification cache to
// quickly validate applications at time of execve(2). The trouble
// is that for the kernel creates the cache entry at the time of the
// mmap(2) call, before we have a chance to write either the code to
// sign or the signature header+hashes. The fix is to invalidate
// all cached data associated with the output file, thus discarding
// the bogus prematurely-cached signature.
msync(Buf, FileOff + Size, MS_INVALIDATE);
#endif
}