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[Mach-O] Handling for special library ordinals used in binding information #7078

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merged 1 commit into from
Jul 14, 2025
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[Mach-O] Handling for special library ordinals used in binding information #7078

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100 changes: 81 additions & 19 deletions view/macho/machoview.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2093,10 +2093,74 @@ bool MachoView::InitializeHeader(MachOHeader& header, bool isMainHeader, uint64_
if (objcProcessor)
objcProcessor->AddRelocatedPointer(relocationLocation, slidTarget);
}
for (auto& [relocation, name] : header.externalRelocations)
for (auto& [relocation, name, ordinal] : header.bindingRelocations)
{
if (auto symbol = GetSymbolByRawName(name, GetExternalNameSpace()); symbol)
DefineRelocation(m_arch, relocation, symbol, relocation.address);
bool handled = false;

switch (ordinal)
{
case BindSpecialDylibSelf:
if (auto symbol = GetSymbolByRawName(name, GetInternalNameSpace()); symbol)
{
DefineRelocation(m_arch, relocation, symbol, relocation.address);
if (objcProcessor)
objcProcessor->AddRelocatedPointer(relocation.address, symbol->GetAddress());
handled = true;
}
break;

case BindSpecialDylibMainExecutable:
case BindSpecialDylibFlatLookup:
case BindSpecialDylibWeakLookup:
// In cases where we are the primary executable, flat lookup should find us first,
// it seems like our best course of action is to try and find internally first on
// executables, and externally on libraries.
if (header.ident.filetype == MH_EXECUTE)
{
if (auto symbol = GetSymbolByRawName(name, GetInternalNameSpace()); symbol)
{
DefineRelocation(m_arch, relocation, symbol, relocation.address);
if (objcProcessor)
objcProcessor->AddRelocatedPointer(relocation.address, symbol->GetAddress());
handled = true;
}
else if (auto symbol = GetSymbolByRawName(name, GetExternalNameSpace()); symbol)
{
DefineRelocation(m_arch, relocation, symbol, relocation.address);
handled = true;
}
}
else
{
if (auto symbol = GetSymbolByRawName(name, GetExternalNameSpace()); symbol)
{
DefineRelocation(m_arch, relocation, symbol, relocation.address);
handled = true;
}
else if (auto symbol = GetSymbolByRawName(name, GetInternalNameSpace()); symbol)
{
DefineRelocation(m_arch, relocation, symbol, relocation.address);
if (objcProcessor)
objcProcessor->AddRelocatedPointer(relocation.address, symbol->GetAddress());
handled = true;
}
}
break;

default:
if (ordinal > 0)
{
if (auto symbol = GetSymbolByRawName(name, GetExternalNameSpace()); symbol)
{
DefineRelocation(m_arch, relocation, symbol, relocation.address);
handled = true;
}
}
break;
}

if (!handled)
m_logger->LogError("Failed to find external symbol '%s', couldn't bind symbol at 0x%llx", name.c_str(), relocation.address);
}

auto relocationHandler = m_arch->GetRelocationHandler("Mach-O");
Expand Down Expand Up @@ -2848,7 +2912,7 @@ void MachoView::ParseDynamicTable(BinaryReader& reader, MachOHeader& header, BNS
BNRelocationInfo externReloc;

BNSymbolType symtype = incomingType;
// uint64_t ordinal = 0;
uint64_t ordinal = 0;
// int64_t addend = 0;
uint64_t segmentIndex = 0;
uint64_t address = 0;
Expand All @@ -2866,7 +2930,7 @@ void MachoView::ParseDynamicTable(BinaryReader& reader, MachOHeader& header, BNS
switch (opcode)
{
case BindOpcodeDone:
// ordinal = 0;
ordinal = 0;
// addend = 0;
segmentIndex = 0;
address = 0;
Expand All @@ -2876,9 +2940,9 @@ void MachoView::ParseDynamicTable(BinaryReader& reader, MachOHeader& header, BNS
type = 0;
symtype = incomingType;
break;
case BindOpcodeSetDylibOrdinalImmediate: /* ordinal = imm; */ break;
case BindOpcodeSetDylibOrdinalULEB: /* ordinal = */ readLEB128(table, tableSize, i); break;
case BindOpcodeSetDylibSpecialImmediate: /* ordinal = -imm; */ break;
case BindOpcodeSetDylibOrdinalImmediate: ordinal = imm;break;
case BindOpcodeSetDylibOrdinalULEB: ordinal = readLEB128(table, tableSize, i); break;
case BindOpcodeSetDylibSpecialImmediate: ordinal = -imm; break;
case BindOpcodeSetSymbolTrailingFlagsImmediate:
/* flags = imm; */
name = (char*)&table[i];
Expand Down Expand Up @@ -2911,8 +2975,7 @@ void MachoView::ParseDynamicTable(BinaryReader& reader, MachOHeader& header, BNS
externReloc.size = m_addressSize;
externReloc.pcRelative = false;
externReloc.external = true;
header.externalRelocations.emplace_back(externReloc, string(name));

header.bindingRelocations.emplace_back(externReloc, string(name), ordinal);
address += m_addressSize;
break;
case BindOpcodeDoBindAddAddressULEB:
Expand All @@ -2925,7 +2988,7 @@ void MachoView::ParseDynamicTable(BinaryReader& reader, MachOHeader& header, BNS
externReloc.size = m_addressSize;
externReloc.pcRelative = false;
externReloc.external = true;
header.externalRelocations.emplace_back(externReloc, string(name));
header.bindingRelocations.emplace_back(externReloc, string(name), ordinal);

address += m_addressSize;
address += readLEB128(table, tableSize, i);
Expand All @@ -2940,7 +3003,7 @@ void MachoView::ParseDynamicTable(BinaryReader& reader, MachOHeader& header, BNS
externReloc.size = m_addressSize;
externReloc.pcRelative = false;
externReloc.external = true;
header.externalRelocations.emplace_back(externReloc, string(name));
header.bindingRelocations.emplace_back(externReloc, string(name), ordinal);
address += m_addressSize;
address += (imm * m_addressSize);
break;
Expand All @@ -2959,7 +3022,7 @@ void MachoView::ParseDynamicTable(BinaryReader& reader, MachOHeader& header, BNS
externReloc.size = m_addressSize;
externReloc.pcRelative = false;
externReloc.external = true;
header.externalRelocations.emplace_back(externReloc, string(name));
header.bindingRelocations.emplace_back(externReloc, string(name), ordinal);

address += skip + m_addressSize;
}
Expand Down Expand Up @@ -3288,7 +3351,7 @@ void MachoView::ParseChainedFixups(
{
uint32_t importEntry = parentReader.Read32();
dyld_chained_import import = *(reinterpret_cast<dyld_chained_import*>(&importEntry));
processChainedImport(import.lib_ordinal, 0, import.name_offset, import.weak_import, parentReader);
processChainedImport(static_cast<int8_t>(import.lib_ordinal), 0, import.name_offset, import.weak_import, parentReader);
}
break;
}
Expand All @@ -3298,7 +3361,7 @@ void MachoView::ParseChainedFixups(
{
dyld_chained_import_addend import;
parentReader.Read(&import, sizeof(import));
processChainedImport(import.lib_ordinal, import.addend, import.name_offset, import.weak_import, parentReader);
processChainedImport(static_cast<int8_t>(import.lib_ordinal), import.addend, import.name_offset, import.weak_import, parentReader);
}
break;
}
Expand All @@ -3308,7 +3371,7 @@ void MachoView::ParseChainedFixups(
{
dyld_chained_import_addend64 import;
parentReader.Read(&import, sizeof(import));
processChainedImport(import.lib_ordinal, import.addend, import.name_offset, import.weak_import, parentReader);
processChainedImport(static_cast<int16_t>(import.lib_ordinal), import.addend, import.name_offset, import.weak_import, parentReader);
}
break;
}
Expand Down Expand Up @@ -3521,7 +3584,7 @@ void MachoView::ParseChainedFixups(
chainEntryAddress += (nextEntryStrideCount * strideSize);
if (chainEntryAddress > pageAddress + starts.page_size)
{
m_logger->LogDebug("Chained Fixups: Pointer at %llx left page",
m_logger->LogError("Chained Fixups: Pointer at %llx left page",
GetStart() + ((chainEntryAddress - (nextEntryStrideCount * strideSize))) - m_universalImageOffset);
fixupsDone = true;
}
Expand All @@ -3546,9 +3609,8 @@ void MachoView::ParseChainedFixups(
externReloc.address = targetAddress;
externReloc.size = m_addressSize;
externReloc.pcRelative = false;
externReloc.external = true;
externReloc.addend = entry.addend;
header.externalRelocations.emplace_back(externReloc, entry.name);
header.bindingRelocations.emplace_back(externReloc, entry.name, entry.lib_ordinal);
}
else
{
Expand Down
16 changes: 15 additions & 1 deletion view/macho/machoview.h
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Original file line number Diff line number Diff line change
Expand Up @@ -818,6 +818,13 @@ namespace BinaryNinja
RebaseOpcodeDoRebaseUlebTimesSkippingUleb = 0x80u, // REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB
};

enum BindSpecial {
BindSpecialDylibSelf = 0, // BIND_SPECIAL_DYLIB_SELF
BindSpecialDylibMainExecutable = -1, // BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE
BindSpecialDylibFlatLookup = -2, // BIND_SPECIAL_DYLIB_FLAT_LOOKUP
BindSpecialDylibWeakLookup = -3 // BIND_SPECIAL_DYLIB_WEAK_LOOKUP
};

enum BindOpcode {
BindOpcodeMask = 0xF0u, // BIND_OPCODE_MASK
BindImmediateMask = 0x0Fu, // BIND_IMMEDIATE_MASK
Expand Down Expand Up @@ -1375,6 +1382,13 @@ namespace BinaryNinja
uint32_t reserved;
};

struct BoundRelocation
{
BNRelocationInfo info;
std::string name;
int64_t ordinal;
};

struct MachOHeader {
bool isMainHeader = false;

Expand All @@ -1386,7 +1400,7 @@ namespace BinaryNinja
std::vector<std::pair<uint64_t, bool>> entryPoints;
std::vector<uint64_t> m_entryPoints; //list of entrypoints

std::vector<std::pair<BNRelocationInfo, std::string>> externalRelocations;
std::vector<BoundRelocation> bindingRelocations;
std::vector<BNRelocationInfo> rebaseRelocations;

symtab_command symtab;
Expand Down