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[llvm-objcopy][MachO] Add support for LC_CODE_SIGNATURE 

This diff adds support for copying binaries
containing a LC_CODE_SIGNATURE load command.

Test plan: make check-all

Differential revision: https://reviews.llvm.org/D81768
This commit is contained in:
Alexander Shaposhnikov 2020-06-15 18:55:59 -07:00
parent 18e356b75d
commit 913bc312b5
7 changed files with 120 additions and 33 deletions
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40
llvm/test/tools/llvm-objcopy/MachO/code_signature_lc.test Normal file
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@ -0,0 +1,40 @@
# RUN: yaml2obj %s -o %t
## Verify that the input file is valid and contains the expected load command.
# RUN: llvm-objdump --private-headers %t | FileCheck %s
# CHECK: cmd LC_CODE_SIGNATURE
# CHECK-NEXT: cmdsize 16
# CHECK-NEXT: dataoff 124
# CHECK-NEXT: datasize 16
# RUN: llvm-objcopy %t %t.copy
# RUN: cmp %t %t.copy
--- !mach-o
FileHeader:
magic: 0xFEEDFACF
cputype: 0x01000007
cpusubtype: 0x80000003
filetype: 0x00000002
ncmds: 2
sizeofcmds: 88
flags: 0x00218085
reserved: 0x00000000
LoadCommands:
- cmd: LC_SEGMENT_64
cmdsize: 72
segname: __LINKEDIT
vmaddr: 4294979584
vmsize: 4096
fileoff: 120
filesize: 20
maxprot: 7
initprot: 1
nsects: 0
flags: 0
- cmd: LC_CODE_SIGNATURE
cmdsize: 16
dataoff: 124
datasize: 16
...

22
llvm/tools/llvm-objcopy/MachO/MachOLayoutBuilder.cpp
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@ -216,10 +216,22 @@ uint64_t MachOLayoutBuilder::layoutRelocations(uint64_t Offset) {
}
Error MachOLayoutBuilder::layoutTail(uint64_t Offset) {
// If we are building the layout of an executable or dynamic library
// which does not have any segments other than __LINKEDIT,
// the Offset can be equal to zero by this time. It happens because of the
// convention that in such cases the file offsets specified by LC_SEGMENT start
// with zero (unlike the case of a relocatable object file).
const bool IsObject = O.Header.FileType == MachO::HeaderFileType::MH_OBJECT;
const uint64_t HeaderSize =
Is64Bit ? sizeof(MachO::mach_header_64) : sizeof(MachO::mach_header);
assert((!IsObject || Offset >= HeaderSize + O.Header.SizeOfCmds) &&
"Incorrect tail offset");
Offset = std::max(Offset, HeaderSize + O.Header.SizeOfCmds);
// The order of LINKEDIT elements is as follows:
// rebase info, binding info, weak binding info, lazy binding info, export
// trie, data-in-code, symbol table, indirect symbol table, symbol table
// strings.
// strings, code signature.
uint64_t NListSize = Is64Bit ? sizeof(MachO::nlist_64) : sizeof(MachO::nlist);
uint64_t StartOfLinkEdit = Offset;
uint64_t StartOfRebaseInfo = StartOfLinkEdit;
@ -238,8 +250,10 @@ Error MachOLayoutBuilder::layoutTail(uint64_t Offset) {
uint64_t StartOfSymbolStrings =
StartOfIndirectSymbols +
sizeof(uint32_t) * O.IndirectSymTable.Symbols.size();
uint64_t StartOfCodeSignature =
StartOfSymbolStrings + StrTableBuilder.getSize();
uint64_t LinkEditSize =
(StartOfSymbolStrings + StrTableBuilder.getSize()) - StartOfLinkEdit;
(StartOfCodeSignature + O.CodeSignature.Data.size()) - StartOfLinkEdit;
// Now we have determined the layout of the contents of the __LINKEDIT
// segment. Update its load command.
@ -265,6 +279,10 @@ Error MachOLayoutBuilder::layoutTail(uint64_t Offset) {
auto &MLC = LC.MachOLoadCommand;
auto cmd = MLC.load_command_data.cmd;
switch (cmd) {
case MachO::LC_CODE_SIGNATURE:
MLC.linkedit_data_command_data.dataoff = StartOfCodeSignature;
MLC.linkedit_data_command_data.datasize = O.CodeSignature.Data.size();
break;
case MachO::LC_SYMTAB:
MLC.symtab_command_data.symoff = StartOfSymbols;
MLC.symtab_command_data.nsyms = O.SymTable.Symbols.size();

34
llvm/tools/llvm-objcopy/MachO/MachOReader.cpp
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@ -119,6 +119,9 @@ void MachOReader::readLoadCommands(Object &O) const {
for (auto LoadCmd : MachOObj.load_commands()) {
LoadCommand LC;
switch (LoadCmd.C.cmd) {
case MachO::LC_CODE_SIGNATURE:
O.CodeSignatureCommandIndex = O.LoadCommands.size();
break;
case MachO::LC_SEGMENT:
LC.Sections = extractSections<MachO::section, MachO::segment_command>(
LoadCmd, MachOObj, NextSectionIndex);
@ -247,26 +250,26 @@ void MachOReader::readExportInfo(Object &O) const {
O.Exports.Trie = MachOObj.getDyldInfoExportsTrie();
}
void MachOReader::readDataInCodeData(Object &O) const {
if (!O.DataInCodeCommandIndex)
void MachOReader::readLinkData(Object &O, Optional<size_t> LCIndex,
LinkData &LD) const {
if (!LCIndex)
return;
const MachO::linkedit_data_command &LDC =
O.LoadCommands[*O.DataInCodeCommandIndex]
.MachOLoadCommand.linkedit_data_command_data;
const MachO::linkedit_data_command &LC =
O.LoadCommands[*LCIndex].MachOLoadCommand.linkedit_data_command_data;
LD.Data =
arrayRefFromStringRef(MachOObj.getData().substr(LC.dataoff, LC.datasize));
}
O.DataInCode.Data = arrayRefFromStringRef(
MachOObj.getData().substr(LDC.dataoff, LDC.datasize));
void MachOReader::readCodeSignature(Object &O) const {
return readLinkData(O, O.CodeSignatureCommandIndex, O.CodeSignature);
}
void MachOReader::readDataInCodeData(Object &O) const {
return readLinkData(O, O.DataInCodeCommandIndex, O.DataInCode);
}
void MachOReader::readFunctionStartsData(Object &O) const {
if (!O.FunctionStartsCommandIndex)
return;
const MachO::linkedit_data_command &LDC =
O.LoadCommands[*O.FunctionStartsCommandIndex]
.MachOLoadCommand.linkedit_data_command_data;
O.FunctionStarts.Data = arrayRefFromStringRef(
MachOObj.getData().substr(LDC.dataoff, LDC.datasize));
return readLinkData(O, O.FunctionStartsCommandIndex, O.FunctionStarts);
}
void MachOReader::readIndirectSymbolTable(Object &O) const {
@ -316,6 +319,7 @@ std::unique_ptr<Object> MachOReader::create() const {
readWeakBindInfo(*Obj);
readLazyBindInfo(*Obj);
readExportInfo(*Obj);
readCodeSignature(*Obj);
readDataInCodeData(*Obj);
readFunctionStartsData(*Obj);
readIndirectSymbolTable(*Obj);

2
llvm/tools/llvm-objcopy/MachO/MachOReader.h
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@ -36,6 +36,8 @@ class MachOReader : public Reader {
void readWeakBindInfo(Object &O) const;
void readLazyBindInfo(Object &O) const;
void readExportInfo(Object &O) const;
void readLinkData(Object &O, Optional<size_t> LCIndex, LinkData &LD) const;
void readCodeSignature(Object &O) const;
void readDataInCodeData(Object &O) const;
void readFunctionStartsData(Object &O) const;
void readIndirectSymbolTable(Object &O) const;

50
llvm/tools/llvm-objcopy/MachO/MachOWriter.cpp
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@ -89,6 +89,15 @@ size_t MachOWriter::totalSize() const {
sizeof(uint32_t) * O.IndirectSymTable.Symbols.size());
}
if (O.CodeSignatureCommandIndex) {
const MachO::linkedit_data_command &LinkEditDataCommand =
O.LoadCommands[*O.CodeSignatureCommandIndex]
.MachOLoadCommand.linkedit_data_command_data;
if (LinkEditDataCommand.dataoff)
Ends.push_back(LinkEditDataCommand.dataoff +
LinkEditDataCommand.datasize);
}
if (O.DataInCodeCommandIndex) {
const MachO::linkedit_data_command &LinkEditDataCommand =
O.LoadCommands[*O.DataInCodeCommandIndex]
@ -381,28 +390,27 @@ void MachOWriter::writeIndirectSymbolTable() {
}
}
void MachOWriter::writeDataInCodeData() {
if (!O.DataInCodeCommandIndex)
void MachOWriter::writeLinkData(Optional<size_t> LCIndex, const LinkData &LD) {
if (!LCIndex)
return;
const MachO::linkedit_data_command &LinkEditDataCommand =
O.LoadCommands[*O.DataInCodeCommandIndex]
.MachOLoadCommand.linkedit_data_command_data;
O.LoadCommands[*LCIndex].MachOLoadCommand.linkedit_data_command_data;
char *Out = (char *)B.getBufferStart() + LinkEditDataCommand.dataoff;
assert((LinkEditDataCommand.datasize == O.DataInCode.Data.size()) &&
"Incorrect data in code data size");
memcpy(Out, O.DataInCode.Data.data(), O.DataInCode.Data.size());
assert((LinkEditDataCommand.datasize == LD.Data.size()) &&
"Incorrect data size");
memcpy(Out, LD.Data.data(), LD.Data.size());
}
void MachOWriter::writeCodeSignatureData() {
return writeLinkData(O.CodeSignatureCommandIndex, O.CodeSignature);
}
void MachOWriter::writeDataInCodeData() {
return writeLinkData(O.DataInCodeCommandIndex, O.DataInCode);
}
void MachOWriter::writeFunctionStartsData() {
if (!O.FunctionStartsCommandIndex)
return;
const MachO::linkedit_data_command &LinkEditDataCommand =
O.LoadCommands[*O.FunctionStartsCommandIndex]
.MachOLoadCommand.linkedit_data_command_data;
char *Out = (char *)B.getBufferStart() + LinkEditDataCommand.dataoff;
assert((LinkEditDataCommand.datasize == O.FunctionStarts.Data.size()) &&
"Incorrect function starts data size");
memcpy(Out, O.FunctionStarts.Data.data(), O.FunctionStarts.Data.size());
return writeLinkData(O.FunctionStartsCommandIndex, O.FunctionStarts);
}
void MachOWriter::writeTail() {
@ -450,6 +458,16 @@ void MachOWriter::writeTail() {
&MachOWriter::writeIndirectSymbolTable);
}
if (O.CodeSignatureCommandIndex) {
const MachO::linkedit_data_command &LinkEditDataCommand =
O.LoadCommands[*O.CodeSignatureCommandIndex]
.MachOLoadCommand.linkedit_data_command_data;
if (LinkEditDataCommand.dataoff)
Queue.emplace_back(LinkEditDataCommand.dataoff,
&MachOWriter::writeCodeSignatureData);
}
if (O.DataInCodeCommandIndex) {
const MachO::linkedit_data_command &LinkEditDataCommand =
O.LoadCommands[*O.DataInCodeCommandIndex]

2
llvm/tools/llvm-objcopy/MachO/MachOWriter.h
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@ -45,6 +45,8 @@ class MachOWriter {
void writeLazyBindInfo();
void writeExportInfo();
void writeIndirectSymbolTable();
void writeLinkData(Optional<size_t> LCIndex, const LinkData &LD);
void writeCodeSignatureData();
void writeDataInCodeData();
void writeFunctionStartsData();
void writeTail();

3
llvm/tools/llvm-objcopy/MachO/Object.h
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@ -302,9 +302,12 @@ struct Object {
IndirectSymbolTable IndirectSymTable;
LinkData DataInCode;
LinkData FunctionStarts;
LinkData CodeSignature;
Optional<uint32_t> SwiftVersion;
/// The index of LC_CODE_SIGNATURE load command if present.
Optional<size_t> CodeSignatureCommandIndex;
/// The index of LC_SYMTAB load command if present.
Optional<size_t> SymTabCommandIndex;
/// The index of LC_DYLD_INFO or LC_DYLD_INFO_ONLY load command if present.