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dsc_extractor.cpp
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dsc_extractor.cpp
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/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
*
* Copyright (c) 2011 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/syslimits.h>
#include <libkern/OSByteOrder.h>
#include <mach-o/fat.h>
#include <mach-o/arch.h>
#include <mach-o/loader.h>
#include <Availability.h>
#define NO_ULEB
#include "Architectures.hpp"
#include "MachOFileAbstraction.hpp"
#include "CacheFileAbstraction.hpp"
#include "dsc_iterator.h"
#include "dsc_extractor.h"
#include "MachOTrie.hpp"
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <dispatch/dispatch.h>
#include <string>
#include <mach/mach.h>
struct seg_info
{
seg_info(const char* n, uint64_t o, uint64_t s)
: segName(n), offset(o), sizem(s) { }
const char* segName;
uint64_t offset;
uint64_t sizem;
};
class CStringHash {
public:
size_t operator()(const char* __s) const {
size_t __h = 0;
for ( ; *__s; ++__s)
__h = 5 * __h + *__s;
return __h;
};
};
class CStringEquals {
public:
bool operator()(const char* left, const char* right) const { return (strcmp(left, right) == 0); }
};
typedef std::unordered_map<const char*, std::vector<seg_info>, CStringHash, CStringEquals> NameToSegments;
// Filter to find individual symbol re-exports in trie
class NotReExportSymbol {
public:
NotReExportSymbol(const std::set<int> &rd) :_reexportDeps(rd) {}
bool operator()(const mach_o::trie::Entry &entry) const {
bool result = isSymbolReExport(entry);
if (result) {
// <rdar://problem/17671438> Xcode 6 leaks in dyld_shared_cache_extract_dylibs
::free((void*)entry.name);
const_cast<mach_o::trie::Entry*>(&entry)->name = NULL;
}
return result;
}
private:
bool isSymbolReExport(const mach_o::trie::Entry &entry) const {
if ( (entry.flags & EXPORT_SYMBOL_FLAGS_KIND_MASK) != EXPORT_SYMBOL_FLAGS_KIND_REGULAR )
return true;
if ( (entry.flags & EXPORT_SYMBOL_FLAGS_REEXPORT) == 0 )
return true;
// If the symbol comes from a dylib that is re-exported, this is not an individual symbol re-export
if ( _reexportDeps.count((int)entry.other) != 0 )
return true;
return false;
}
const std::set<int> &_reexportDeps;
};
static void append_uleb128(uint64_t value, std::vector<uint8_t>& out) {
uint8_t byte;
do {
byte = value & 0x7F;
value &= ~0x7F;
if ( value != 0 )
byte |= 0x80;
out.push_back(byte);
value = value >> 7;
} while( byte >= 0x80 );
}
class RebaseMaker {
public:
std::vector<uint8_t> relocs;
uintptr_t segmentStartMapped;
uintptr_t segmentEndMapped;
int32_t currentSegment;
RebaseMaker(int32_t _currentSegment, uintptr_t _segmentStartMapped, uintptr_t _segmentEndMapped) : currentSegment(_currentSegment), segmentStartMapped(_segmentStartMapped), segmentEndMapped(_segmentEndMapped) {
relocs.push_back(REBASE_OPCODE_SET_TYPE_IMM | REBASE_TYPE_POINTER);
}
void addSlide(uint8_t* loc) {
uintptr_t l = (uintptr_t)loc;
if (l < segmentStartMapped || l >= segmentEndMapped) {
abort();
return;
}
addReloc(currentSegment, l - segmentStartMapped);
}
void addReloc(int32_t segment, uintptr_t segmentOffset) {
relocs.push_back(REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB | segment);
append_uleb128(segmentOffset, relocs);
relocs.push_back(REBASE_OPCODE_DO_REBASE_IMM_TIMES | 1);
}
void finish() {
relocs.push_back(REBASE_OPCODE_DONE);
}
};
static void rebaseChain(uint8_t* pageContent, uint16_t startOffset, uintptr_t slideAmount, const dyldCacheSlideInfo2<LittleEndian>* slideInfo, uint8_t* filePage, uint8_t* segmentStart, uint8_t* segmentEnd, RebaseMaker& slides)
{
const uintptr_t deltaMask = (uintptr_t)(slideInfo->delta_mask());
const uintptr_t valueMask = ~deltaMask;
const uintptr_t valueAdd = (uintptr_t)(slideInfo->value_add());
const unsigned deltaShift = __builtin_ctzll(deltaMask) - 2;
uint32_t pageOffset = startOffset;
uint32_t delta = 1;
while ( delta != 0 ) {
uint8_t* loc = pageContent + pageOffset;
uintptr_t rawValue = *((uintptr_t*)loc);
delta = (uint32_t)((rawValue & deltaMask) >> deltaShift);
uintptr_t value = (rawValue & valueMask);
if ( value != 0 ) {
value += valueAdd;
value += slideAmount;
}
//*((uintptr_t*)loc) = value;
uint8_t* outLoc = filePage + pageOffset;
if (outLoc >= segmentStart && outLoc < segmentEnd) {
if (*((uintptr_t*)outLoc) != rawValue) {
abort();
}
*((uintptr_t*)outLoc) = value;
slides.addSlide(outLoc);
}
//dyld::log(" pageOffset=0x%03X, loc=%p, org value=0x%08llX, new value=0x%08llX, delta=0x%X\n", pageOffset, loc, (uint64_t)rawValue, (uint64_t)value, delta);
pageOffset += delta;
}
}
template <typename A>
std::vector<uint8_t> slideOutput(macho_header<typename A::P>* mh, uint64_t textOffsetInCache, const void* mapped_cache) {
typedef typename A::P P;
auto cacheBase = ((uint64_t)mh->getSegment("__TEXT")->vmaddr()) - textOffsetInCache;
auto dataSegment = mh->getSegment("__DATA");
// grab the slide information from the cache
const dyldCacheHeader<LittleEndian>* header = (dyldCacheHeader<LittleEndian>*)mapped_cache;
const dyldCacheFileMapping<LittleEndian>* mappings = (dyldCacheFileMapping<LittleEndian>*)((char*)mapped_cache + header->mappingOffset());
const dyldCacheFileMapping<LittleEndian>* dataMapping = &mappings[1];
uint64_t dataStartAddress = dataMapping->address();
const dyldCacheSlideInfo<LittleEndian>* slideInfo = (dyldCacheSlideInfo<LittleEndian>*)((char*)mapped_cache+header->slideInfoOffset());
const dyldCacheSlideInfo2<LittleEndian>* slideHeader = (dyldCacheSlideInfo2<LittleEndian>*)(slideInfo);
const uint32_t page_size = slideHeader->page_size();
const uint16_t* page_starts = (uint16_t*)((long)(slideInfo) + slideHeader->page_starts_offset());
const uint16_t* page_extras = (uint16_t*)((long)(slideInfo) + slideHeader->page_extras_offset());
auto slide = 0;
auto slideOneSegment = [=](const macho_segment_command<P>* segment, int segmentIndex) {
auto segmentInFile = (uint8_t*)mh + segment->fileoff();
RebaseMaker rebaseMaker(segmentIndex, (uintptr_t)segmentInFile, (uintptr_t)(segmentInFile + segment->filesize()));
uint64_t startAddr = segment->vmaddr() - dataStartAddress;
uint32_t startPage = startAddr / 0x1000;
uint32_t startAddrOff = startAddr & 0xfff;
uint32_t endPage = (((segment->vmaddr() + segment->vmsize() + 0xfffull) & ~0xfffull) - dataStartAddress) / 0x1000;
auto segmentEnd = segmentInFile + segment->filesize();
for (int i=startPage; i < endPage; ++i) {
uint8_t* filePage = segmentInFile + ((i - startPage) * 0x1000) - startAddrOff;
uint8_t* page = (uint8_t*)mapped_cache + dataMapping->file_offset() + (i * 0x1000);
uint16_t pageEntry = page_starts[i];
//dyld::log("page[%d]: page_starts[i]=0x%04X\n", i, pageEntry);
if ( pageEntry == DYLD_CACHE_SLIDE_PAGE_ATTR_NO_REBASE )
continue;
if ( pageEntry & DYLD_CACHE_SLIDE_PAGE_ATTR_EXTRA ) {
uint16_t chainIndex = (pageEntry & 0x3FFF);
bool done = false;
while ( !done ) {
uint16_t info = page_extras[chainIndex];
uint16_t pageStartOffset = (info & 0x3FFF)*4;
//dyld::log(" chain[%d] pageOffset=0x%03X\n", chainIndex, pageStartOffset);
rebaseChain(page, pageStartOffset, slide, slideHeader, filePage, segmentInFile, segmentEnd, rebaseMaker);
done = (info & DYLD_CACHE_SLIDE_PAGE_ATTR_END);
++chainIndex;
}
}
else {
uint32_t pageOffset = pageEntry * 4;
//dyld::log(" start pageOffset=0x%03X\n", pageOffset);
rebaseChain(page, pageOffset, slide, slideHeader, filePage, segmentInFile, segmentEnd, rebaseMaker);
}
}
rebaseMaker.finish();
return rebaseMaker.relocs;
};
auto ret = slideOneSegment(mh->getSegment("__DATA"), 1);
auto constData = mh->getSegment("__DATA_CONST");
if (constData) {
auto c = slideOneSegment(constData, 2);
ret.insert(ret.end() - 1, c.begin(), c.end());
}
return ret;
}
// copied from ObjC2Abstraction
struct my_objc_object {
uint64_t isa;
};
struct my_objc_class: my_objc_object {
uint64_t superclass;
uint64_t cache;
uint64_t vtable;
uint64_t data;
};
struct my_objc_class_data {
uint32_t flags;
uint32_t instanceStart;
uint32_t instanceSize;
uint64_t ivarLayout;
uint64_t name;
uint64_t baseMethods;
uint64_t baseProtocols;
uint64_t ivars;
uint64_t weakIvarLayout;
uint64_t baseProperties;
};
struct my_objc_method {
uint64_t name;
uint64_t type;
uint64_t imp;
};
struct my_objc_method_list {
uint32_t entsize;
uint32_t count;
my_objc_method methods[];
};
struct seg_info2
{
seg_info2(const char* n, uint64_t o, uint64_t s, uint64_t vm, const void* mh)
: segName(n), offset(o), sizem(s), vmaddr(vm), machHeader(mh) { }
const char* segName;
uint64_t offset;
uint64_t sizem;
uint64_t vmaddr;
const void* machHeader;
};
template <typename A>
int fixupObjc(macho_header<typename A::P>* mh, uint64_t textOffsetInCache, const void* mapped_cache) {
typedef typename A::P P;
auto cacheBase = ((uint64_t)mh->getSegment("__TEXT")->vmaddr()) - textOffsetInCache;
const macho_section<P>* methnameSec = mh->getSection("__TEXT", "__objc_methname");
// method name to in-memory address
std::unordered_map<std::string, uint64_t> methnameToAddr;
for (uint64_t off = 0; off < methnameSec->size();) {
const char* methname = (const char*)mh + methnameSec->offset() + off;
methnameToAddr[methname] = methnameSec->addr() + off;
off += strlen(methname) + 1;
}
std::unordered_map<uint64_t, uint64_t> unfixedSelectorToFixedIndex;
const macho_section<P>* selrefsSec = mh->getSection("__DATA", "__objc_selrefs");
uint64_t* selrefsArr = (uint64_t*)(((char*)mh) + selrefsSec->offset());
for (uint64_t index = 0; index < selrefsSec->size() / sizeof(uint64_t); index++) {
uint64_t origSel = selrefsArr[index];
const char* origStr = (const char*)mapped_cache + ((selrefsArr[index] & 0xffffffffffffULL) - cacheBase);
printf("%p\n", origStr);
selrefsArr[index] = methnameToAddr[origStr];
unfixedSelectorToFixedIndex[origSel] = index;
}
// next, fixup the individual classes
auto dataSeg = mh->getSegment("__DATA");
auto dataConstSeg = mh->getSegment("__DATA_CONST");
auto addrToMyDataConstMapped = [=](uint64_t addr) {
if (addr == 0) return (const char*)nullptr;
return (const char*)mh + dataConstSeg->fileoff() + (addr - dataConstSeg->vmaddr());
};
auto addrToMyDataMapped = [=](uint64_t addr) {
if (addr == 0) return (const char*)nullptr;
if (!(addr >= dataSeg->vmaddr() && addr < dataSeg->vmaddr() + dataSeg->vmsize()) && dataConstSeg) {
return addrToMyDataConstMapped(addr);
}
return (const char*)mh + dataSeg->fileoff() + (addr - dataSeg->vmaddr());
};
auto addrToTheirTextMapped = [=](uint64_t addr) {
if (addr == 0) return (const char*)nullptr;
return (const char*)mapped_cache + (addr - cacheBase);
};
const macho_section<P>* classlistSec = mh->getSection("__DATA", "__objc_classlist");
uint64_t* classesArr = (uint64_t*)(((char*)mh) + classlistSec->offset());
for (uint64_t index = 0; index < classlistSec->size() / sizeof(uint64_t); index++) {
my_objc_class* cls = (my_objc_class*)addrToMyDataMapped(classesArr[index]);
my_objc_class_data* clsData = (my_objc_class_data*)addrToMyDataMapped(cls->data);
if (clsData && clsData->baseMethods) {
my_objc_method_list* methodList = (my_objc_method_list*)addrToMyDataMapped(clsData->baseMethods);
for (int methIndex = 0; methIndex < methodList->count; methIndex++) {
const char* origStr = addrToTheirTextMapped(methodList->methods[methIndex].name);
methodList->methods[methIndex].name = methnameToAddr[origStr];
}
methodList->entsize &= ~3; // clear the optimized flag
}
// todo: protocols
}
// oh, and remove the optimized flag for the image
const macho_section<P>* objcImageInfoSection = mh->getSection("__DATA", "__objc_imageinfo");
uint32_t* objcImageInfo = (uint32_t*)((char*)mh + objcImageInfoSection->offset());
objcImageInfo[1] &= ~(1 << 3);
// fixup lazy pointers
// la_symbol_ptr should point into stub_helper
const macho_dyld_info_command<P>* dyldInfo = (const macho_dyld_info_command<P>*)mh->getLoadCommand(LC_DYLD_INFO_ONLY);
auto runOneLazyBind = [=](uint32_t cmdOff) {
const uint8_t* cmds = (const uint8_t*)mh + dyldInfo->lazy_bind_off() + cmdOff;
const uint8_t* cmdsEnd = (const uint8_t*)mh + dyldInfo->lazy_bind_off() + dyldInfo->lazy_bind_size();
while (cmds < cmdsEnd) {
uint8_t immediate = *cmds & BIND_IMMEDIATE_MASK;
uint8_t opcode = *cmds & BIND_OPCODE_MASK;
++cmds;
switch (opcode) {
case BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
return mach_o::trie::read_uleb128(cmds, cmdsEnd);
}
}
};
const macho_section<P>* lazyStubSec = mh->getSection("__TEXT", "__stub_helper");
// x86_64 specific
uint32_t stubStart, stubSize, stubAddrOffset;
if (mh->cputype() == CPU_TYPE_X86_64) {
stubStart = 0x10;
stubSize = 0xa;
stubAddrOffset = 0x1;
} else if (mh->cputype() == CPU_TYPE_ARM64) {
stubStart = 0x18;
stubSize = 0xc;
stubAddrOffset = 0x8;
} else {
abort();
}
const uint8_t* lazyStubStart = (const uint8_t*)mh + lazyStubSec->offset();
const uint8_t* lazyStubEnd = (const uint8_t*)mh + lazyStubSec->offset() + lazyStubSec->size();
for (const uint8_t* lazyStub = lazyStubStart + stubStart; lazyStub < lazyStubEnd; lazyStub += stubSize) {
uint32_t offset = *(uint32_t*)(lazyStub + stubAddrOffset);
uint64_t stubVMAddr = (uint64_t)(lazyStub - lazyStubStart) + lazyStubSec->addr();
uint32_t lazyBindDataOffset = runOneLazyBind(offset);
uint64_t* data = (uint64_t*)((uint8_t*)mh + dataSeg->fileoff() + lazyBindDataOffset);
*data = stubVMAddr;
}
// arm64: disassemble each function, fix up all the calls to stubs.
if (mh->cputype() == CPU_TYPE_ARM64) {
auto textSeg = mh->getSegment("__TEXT");
auto textSection = mh->getSection("__TEXT", "__text");
auto getBranch = [](uint32_t instruction, uint64_t callSiteAddr) {
// from optimizeArm64CallSites
// skip all but BL or B
if ( (instruction & 0x7C000000) != 0x14000000 )
return (uint64_t)0;
// compute target of branch instruction
int32_t brDelta = (instruction & 0x03FFFFFF) << 2;
if ( brDelta & 0x08000000 )
brDelta |= 0xF0000000;
uint64_t targetAddr = callSiteAddr + (int64_t)brDelta;
return targetAddr;
};
typedef std::unordered_map<const char*, std::vector<seg_info2>, CStringHash, CStringEquals> NameToSegmentsMore;
__block NameToSegmentsMore map_;
__block int result = dyld_shared_cache_iterate(mapped_cache, 0xC0000000 /* should be big enough */,^(const dyld_shared_cache_dylib_info* dylibInfo, const dyld_shared_cache_segment_info* segInfo) {
map_[dylibInfo->path].push_back(seg_info2(segInfo->name, segInfo->fileOffset, segInfo->fileSize, segInfo->address, dylibInfo->machHeader));
});
NameToSegmentsMore map = map_;
std::unordered_map<uint64_t, std::vector<const char*>> addressToSymbolName;
auto addSymbols = [&](macho_header<P>* mhlib, seg_info2 const& linkeditInfo, seg_info2 const& textInfo) {
macho_dyld_info_command<P>* dyldInfoOnly = (macho_dyld_info_command<P>*)mhlib->getLoadCommand(LC_DYLD_INFO_ONLY);
std::vector<mach_o::trie::Entry> exports;
const uint8_t* exportsStart = ((uint8_t*)mapped_cache) + dyldInfoOnly->export_off();
const uint8_t* exportsEnd = exportsStart + dyldInfoOnly->export_size();
mach_o::trie::parseTrie(exportsStart, exportsEnd, exports);
for (auto& e: exports) {
uint64_t address = textInfo.vmaddr + e.address;
addressToSymbolName[address].push_back(e.name);
}
};
auto lookupSymbol = [&](uint64_t address) {
if (addressToSymbolName.count(address) != 0) {
return addressToSymbolName[address];
}
// lookup the library that contains this address
const char* libName = nullptr;
for ( auto it = map.begin(); libName == nullptr && it != map.end(); ++it) {
for (auto& segInfo : it->second) {
if (address >= segInfo.vmaddr && address < segInfo.vmaddr + segInfo.sizem) {
// found the library it sits in
libName = it->first;
break;
}
}
}
{
seg_info2* textSection = nullptr;
seg_info2* linkeditSection = nullptr;
for (auto& segInfo : map[libName]) {
if (strcmp(segInfo.segName, "__LINKEDIT") == 0) {
linkeditSection = &segInfo;
break;
} else if (strcmp(segInfo.segName, "__TEXT") == 0) {
textSection = &segInfo;
break;
}
}
addSymbols((macho_header<P>*)textSection->machHeader, *linkeditSection, *textSection);
}
// ok try again
return addressToSymbolName[address];
};
auto inSomeTextSection = [&](uint64_t address) {
for ( auto it = map.begin(); it != map.end(); ++it) {
for (auto& segInfo : it->second) {
if (strcmp(segInfo.segName, "__TEXT") == 0 && address >= segInfo.vmaddr && address < segInfo.vmaddr + segInfo.sizem) {
return true;
}
}
}
return false;
};
auto runOneLazyBindForName = [=](uint32_t cmdOff) {
const uint8_t* cmds = (const uint8_t*)mh + dyldInfo->lazy_bind_off() + cmdOff;
const uint8_t* cmdsEnd = (const uint8_t*)mh + dyldInfo->lazy_bind_off() + dyldInfo->lazy_bind_size();
while (cmds < cmdsEnd) {
uint8_t immediate = *cmds & BIND_IMMEDIATE_MASK;
uint8_t opcode = *cmds & BIND_OPCODE_MASK;
++cmds;
switch (opcode) {
case BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
mach_o::trie::read_uleb128(cmds, cmdsEnd);
break;
case BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
return (const char*)cmds;
}
}
return (const char*)nullptr;
};
std::unordered_map<std::string, uint64_t> nameToStubAddr;
auto stubItSelfSection = mh->getSection("__TEXT", "__stubs");
const uint64_t stubItSelfSize = 3 * 4;
for (uint32_t stubIndex = 0; stubIndex < stubItSelfSection->size() / stubItSelfSize; stubIndex++ ) {
// copied from above
const uint8_t* lazyStub = lazyStubStart + stubStart + stubSize * stubIndex;
uint32_t offset = *(uint32_t*)(lazyStub + stubAddrOffset);
uint64_t stubVMAddr = (uint64_t)(lazyStub - lazyStubStart) + lazyStubSec->addr();
const char* name = runOneLazyBindForName(offset);
nameToStubAddr[name] = stubItSelfSection->addr() + stubIndex*stubItSelfSize;
}
for (auto itr = nameToStubAddr.begin(); itr != nameToStubAddr.end(); ++itr) {
fprintf(stderr, "%s %p\n", itr->first.c_str(), (void*)itr->second);
}
const uint8_t* textSectionStart = (const uint8_t*)mh + textSection->offset();
const uint8_t* textSectionEnd = (const uint8_t*)mh + textSection->offset() + textSection->size();
std::unordered_map<uint64_t, uint64_t> targetAddrToEndAddr;
for (uint32_t* textPtr = (uint32_t*)textSectionStart; (uint8_t*)textPtr < textSectionEnd; textPtr++) {
uint32_t instruction = *textPtr;
uint64_t callSiteAddr = (uint64_t)((const uint8_t*)textPtr - textSectionStart) + textSection->addr();
if ((instruction & 0xff000000u) == 0x91000000) {
// add
uint32_t& prevInstruction = *(textPtr - 1);
if ((prevInstruction & 0x9f000000u) == 0x90000000) {
// adrp
uint32_t destAdrpR = prevInstruction & 0x1f;
uint32_t srcAddR = (instruction >> 5) & 0x1f;
if (destAdrpR == srcAddR) {
// ok is this a selector?
uint64_t adrpImm = (((prevInstruction >> 5) & 0x7ffff) << 2) | ((prevInstruction >> 29) & 0x3);
uint64_t adrpAddr = (callSiteAddr - 4 + (adrpImm << 12)) & ~0xfffull;
uint64_t addImm = ((instruction >> 10) & 0xfff) << ((instruction >> 22) & 0x3);
uint64_t ptrAddr = adrpAddr + addImm;
const char* pointedTo = addrToTheirTextMapped(ptrAddr);
// debugger?
if (unfixedSelectorToFixedIndex.count(ptrAddr) == 1) {
// found a selector, switch the adrp/add to adrp/ldr, point to the selector's address in the table
// from AdjustForNewSegmentLocation.cpp
uint64_t targetAddress = selrefsSec->addr() + unfixedSelectorToFixedIndex[ptrAddr] * sizeof(uint64_t);
int64_t pageDistance = targetAddress - ((callSiteAddr - 4) & ~0xfff);
int64_t newPage21 = pageDistance >> 12;
prevInstruction = (prevInstruction & 0x9F00001F) | ((newPage21 << 29) & 0x60000000) | ((newPage21 << 3) & 0x00FFFFE0);
*textPtr = (instruction & 0x3ff) | 0xf9400000 | (((pageDistance & 0xfff) >> 3) << 10);
}
}
}
}
uint64_t targetAddr = getBranch(instruction, callSiteAddr);
if (targetAddr == 0 || (targetAddr >= textSeg->vmaddr() && targetAddr < textSeg->vmaddr() + textSeg->vmsize())) {
continue;
}
if (targetAddrToEndAddr.count(targetAddr) == 0) {
auto origTargetAddr = targetAddr;
// yes, this is terribly inefficient and slow. But not too slow.
while (!inSomeTextSection(targetAddr)) {
uint32_t* targetInstrPtr = (uint32_t*)addrToTheirTextMapped(targetAddr);
uint64_t secondTargetAddr = getBranch(*targetInstrPtr, targetAddr);
if (secondTargetAddr == 0) break;
targetAddr = secondTargetAddr;
}
targetAddrToEndAddr[origTargetAddr] = targetAddr;
} else {
targetAddr = targetAddrToEndAddr[targetAddr];
}
// todo: look up the library where targetAddr resides,
// find the function's symbol, get its name,
auto targetNames = lookupSymbol(targetAddr);
// find the same name in our rebase section,
// find its stub,
auto stubAddress = 0;
for (auto targetName : targetNames) {
stubAddress = nameToStubAddr[targetName];
if (stubAddress) break;
if (strcmp(targetName, "___bzero") == 0) {
// hack
stubAddress = nameToStubAddr["_bzero"];
if (stubAddress) break;
}
}
if (!stubAddress) {
abort();
}
// and finally replace the original jump target with the stub
int64_t deltaToFinalTarget = stubAddress - callSiteAddr;
*textPtr = (instruction & 0xFC000000) | ((deltaToFinalTarget >> 2) & 0x03FFFFFF);
//fprintf(stderr, "%p: %08x %p %s\n", (void*)callSiteAddr, instruction, (void*)targetAddr, targetName);
}
}
return 0;
}
template <typename A>
int optimize_linkedit(macho_header<typename A::P>* mh, uint64_t textOffsetInCache, const void* mapped_cache, uint64_t* newSize)
{
typedef typename A::P P;
typedef typename A::P::E E;
typedef typename A::P::uint_t pint_t;
// update header flags
mh->set_flags(mh->flags() & 0x7FFFFFFF); // remove in-cache bit
// update load commands
uint64_t cumulativeFileSize = 0;
const unsigned origLoadCommandsSize = mh->sizeofcmds();
unsigned bytesRemaining = origLoadCommandsSize;
unsigned removedCount = 0;
const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)mh + sizeof(macho_header<P>));
const uint32_t cmdCount = mh->ncmds();
const macho_load_command<P>* cmd = cmds;
macho_segment_command<P>* linkEditSegCmd = NULL;
macho_symtab_command<P>* symtab = NULL;
macho_dysymtab_command<P>* dynamicSymTab = NULL;
macho_linkedit_data_command<P>* functionStarts = NULL;
macho_linkedit_data_command<P>* dataInCode = NULL;
macho_dyld_info_command<P>* dyldInfo = NULL;
uint32_t exportsTrieOffset = 0;
uint32_t exportsTrieSize = 0;
std::set<int> reexportDeps;
int depIndex = 0;
for (uint32_t i = 0; i < cmdCount; ++i) {
bool remove = false;
fprintf(stderr, "Command %x\n", cmd->cmd());
switch ( cmd->cmd() ) {
case macho_segment_command<P>::CMD:
{
// update segment/section file offsets
macho_segment_command<P>* segCmd = (macho_segment_command<P>*)cmd;
segCmd->set_fileoff(cumulativeFileSize);
macho_section<P>* const sectionsStart = (macho_section<P>*)((char*)segCmd + sizeof(macho_segment_command<P>));
macho_section<P>* const sectionsEnd = §ionsStart[segCmd->nsects()];
for(macho_section<P>* sect = sectionsStart; sect < sectionsEnd; ++sect) {
if ( sect->offset() != 0 )
sect->set_offset((uint32_t)(cumulativeFileSize+sect->addr()-segCmd->vmaddr()));
}
if ( strcmp(segCmd->segname(), "__LINKEDIT") == 0 ) {
linkEditSegCmd = segCmd;
}
if ( strcmp(segCmd->segname(), "__DATA") == 0 ) {
segCmd->set_vmsize((segCmd->vmsize() + 0xfff) & ~0xfff);
}
cumulativeFileSize += segCmd->filesize();
}
break;
case LC_DYLD_INFO_ONLY:
{
// zero out all dyld info
/* macho_dyld_info_command<P>* */ dyldInfo = (macho_dyld_info_command<P>*)cmd;
exportsTrieOffset = dyldInfo->export_off();
exportsTrieSize = dyldInfo->export_size();
/*
dyldInfo->set_rebase_off(0);
dyldInfo->set_rebase_size(0);
dyldInfo->set_bind_off(0);
dyldInfo->set_bind_size(0);
dyldInfo->set_weak_bind_off(0);
dyldInfo->set_weak_bind_size(0);
dyldInfo->set_lazy_bind_off(0);
dyldInfo->set_lazy_bind_size(0);
dyldInfo->set_export_off(0);
dyldInfo->set_export_size(0);
*/
}
break;
case LC_SYMTAB:
symtab = (macho_symtab_command<P>*)cmd;
break;
case LC_DYSYMTAB:
dynamicSymTab = (macho_dysymtab_command<P>*)cmd;
break;
case LC_FUNCTION_STARTS:
functionStarts = (macho_linkedit_data_command<P>*)cmd;
break;
case LC_DATA_IN_CODE:
dataInCode = (macho_linkedit_data_command<P>*)cmd;
break;
case LC_LOAD_DYLIB:
case LC_LOAD_WEAK_DYLIB:
case LC_REEXPORT_DYLIB:
case LC_LOAD_UPWARD_DYLIB:
++depIndex;
if ( cmd->cmd() == LC_REEXPORT_DYLIB ) {
reexportDeps.insert(depIndex);
}
break;
case LC_SEGMENT_SPLIT_INFO:
// <rdar://problem/23212513> dylibs iOS 9 dyld caches have bogus LC_SEGMENT_SPLIT_INFO
remove = true;
break;
}
uint32_t cmdSize = cmd->cmdsize();
macho_load_command<P>* nextCmd = (macho_load_command<P>*)(((uint8_t*)cmd)+cmdSize);
if ( remove ) {
::memmove((void*)cmd, (void*)nextCmd, bytesRemaining);
++removedCount;
}
else {
bytesRemaining -= cmdSize;
cmd = nextCmd;
}
}
// zero out stuff removed
::bzero((void*)cmd, bytesRemaining);
// update header
mh->set_ncmds(cmdCount - removedCount);
mh->set_sizeofcmds(origLoadCommandsSize - bytesRemaining);
// rebuild symbol table
if ( linkEditSegCmd == NULL ) {
fprintf(stderr, "__LINKEDIT not found\n");
return -1;
}
if ( symtab == NULL ) {
fprintf(stderr, "LC_SYMTAB not found\n");
return -1;
}
if ( dynamicSymTab == NULL ) {
fprintf(stderr, "LC_DYSYMTAB not found\n");
return -1;
}
if ( dyldInfo == NULL ) {
fprintf(stderr, "dyldInfo not found\n");
return -1;
}
// remove the slide linked list from the dyld cache
// and generate crappy rebase info
std::vector<uint8_t> rebaseInfo = slideOutput<A>(mh, textOffsetInCache, mapped_cache);
linkEditSegCmd->set_fileoff((linkEditSegCmd->fileoff() + 0xfff) & ~0xfff);
const uint64_t newDyldInfoOffset = linkEditSegCmd->fileoff();
uint64_t newDyldInfoSize = 0;
//memcpy((char*)mh + newDyldInfoOffset + newDyldInfoSize, (char*)mapped_cache + dyldInfo->rebase_off(), dyldInfo->rebase_size());
memcpy((char*)mh + newDyldInfoOffset + newDyldInfoSize, rebaseInfo.data(), rebaseInfo.size());
dyldInfo->set_rebase_size((rebaseInfo.size() + 0x7u) & ~0x7u);
dyldInfo->set_rebase_off(newDyldInfoOffset + newDyldInfoSize);
newDyldInfoSize += dyldInfo->rebase_size();
memcpy((char*)mh + newDyldInfoOffset + newDyldInfoSize, (char*)mapped_cache + dyldInfo->bind_off(), dyldInfo->bind_size());
dyldInfo->set_bind_off(newDyldInfoOffset + newDyldInfoSize);
newDyldInfoSize += dyldInfo->bind_size();
memcpy((char*)mh + newDyldInfoOffset + newDyldInfoSize, (char*)mapped_cache + dyldInfo->lazy_bind_off(), dyldInfo->lazy_bind_size());
dyldInfo->set_lazy_bind_off(newDyldInfoOffset + newDyldInfoSize);
newDyldInfoSize += dyldInfo->lazy_bind_size();
memcpy((char*)mh + newDyldInfoOffset + newDyldInfoSize, (char*)mapped_cache + dyldInfo->export_off(), dyldInfo->export_size());
dyldInfo->set_export_off(newDyldInfoOffset + newDyldInfoSize);
newDyldInfoSize += dyldInfo->export_size();
const uint64_t newFunctionStartsOffset = newDyldInfoOffset + newDyldInfoSize;
uint32_t functionStartsSize = 0;
if ( functionStarts != NULL ) {
// copy function starts from original cache file to new mapped dylib file
functionStartsSize = functionStarts->datasize();
memcpy((char*)mh + newFunctionStartsOffset, (char*)mapped_cache + functionStarts->dataoff(), functionStartsSize);
}
const uint64_t newDataInCodeOffset = (newFunctionStartsOffset + functionStartsSize + sizeof(pint_t) - 1) & (-sizeof(pint_t)); // pointer align
uint32_t dataInCodeSize = 0;
if ( dataInCode != NULL ) {
// copy data-in-code info from original cache file to new mapped dylib file
dataInCodeSize = dataInCode->datasize();
memcpy((char*)mh + newDataInCodeOffset, (char*)mapped_cache + dataInCode->dataoff(), dataInCodeSize);
}
std::vector<mach_o::trie::Entry> exports;
if ( exportsTrieSize != 0 ) {
const uint8_t* exportsStart = ((uint8_t*)mapped_cache) + exportsTrieOffset;
const uint8_t* exportsEnd = &exportsStart[exportsTrieSize];
mach_o::trie::parseTrie(exportsStart, exportsEnd, exports);
exports.erase(std::remove_if(exports.begin(), exports.end(), NotReExportSymbol(reexportDeps)), exports.end());
}
// look for local symbol info in unmapped part of shared cache
dyldCacheHeader<E>* header = (dyldCacheHeader<E>*)mapped_cache;
macho_nlist<P>* localNlists = NULL;
uint32_t localNlistCount = 0;
const char* localStrings = NULL;
const char* localStringsEnd = NULL;
bool copyTheLocalSyms = false;
if ( copyTheLocalSyms && header->mappingOffset() > offsetof(dyld_cache_header,localSymbolsSize) ) {
dyldCacheLocalSymbolsInfo<E>* localInfo = (dyldCacheLocalSymbolsInfo<E>*)(((uint8_t*)mapped_cache) + header->localSymbolsOffset());
dyldCacheLocalSymbolEntry<E>* entries = (dyldCacheLocalSymbolEntry<E>*)(((uint8_t*)mapped_cache) + header->localSymbolsOffset() + localInfo->entriesOffset());
macho_nlist<P>* allLocalNlists = (macho_nlist<P>*)(((uint8_t*)localInfo) + localInfo->nlistOffset());
const uint32_t entriesCount = localInfo->entriesCount();
for (uint32_t i=0; i < entriesCount; ++i) {
if ( entries[i].dylibOffset() == textOffsetInCache ) {
uint32_t localNlistStart = entries[i].nlistStartIndex();
localNlistCount = entries[i].nlistCount();
localNlists = &allLocalNlists[localNlistStart];
localStrings = ((char*)localInfo) + localInfo->stringsOffset();
localStringsEnd = &localStrings[localInfo->stringsSize()];
break;
}
}
}
// compute number of symbols in new symbol table
const macho_nlist<P>* const mergedSymTabStart = (macho_nlist<P>*)(((uint8_t*)mapped_cache) + symtab->symoff());
const macho_nlist<P>* const mergedSymTabend = &mergedSymTabStart[symtab->nsyms()];
uint32_t newSymCount = symtab->nsyms();
if ( localNlists != NULL ) {
newSymCount = localNlistCount;
for (const macho_nlist<P>* s = mergedSymTabStart; s != mergedSymTabend; ++s) {
// skip any locals in cache
if ( (s->n_type() & (N_TYPE|N_EXT)) == N_SECT )
continue;
++newSymCount;
}
}
// add room for N_INDR symbols for re-exported symbols
newSymCount += exports.size();
// copy symbol entries and strings from original cache file to new mapped dylib file
const uint64_t newSymTabOffset = (newDataInCodeOffset + dataInCodeSize + sizeof(pint_t) - 1) & (-sizeof(pint_t)); // pointer align
const uint64_t newIndSymTabOffset = newSymTabOffset + newSymCount*sizeof(macho_nlist<P>);
const uint64_t newStringPoolOffset = newIndSymTabOffset + dynamicSymTab->nindirectsyms()*sizeof(uint32_t);
macho_nlist<P>* const newSymTabStart = (macho_nlist<P>*)(((uint8_t*)mh) + newSymTabOffset);
char* const newStringPoolStart = (char*)mh + newStringPoolOffset;
const uint32_t* mergedIndSymTab = (uint32_t*)((char*)mapped_cache + dynamicSymTab->indirectsymoff());
const char* mergedStringPoolStart = (char*)mapped_cache + symtab->stroff();
const char* mergedStringPoolEnd = &mergedStringPoolStart[symtab->strsize()];
macho_nlist<P>* t = newSymTabStart;
int poolOffset = 0;
uint32_t symbolsCopied = 0;
newStringPoolStart[poolOffset++] = '\0'; // first pool entry is always empty string
for (const macho_nlist<P>* s = mergedSymTabStart; s != mergedSymTabend; ++s) {
// if we have better local symbol info, skip any locals here
if ( (localNlists != NULL) && ((s->n_type() & (N_TYPE|N_EXT)) == N_SECT) )
continue;
*t = *s;
t->set_n_strx(poolOffset);
const char* symName = &mergedStringPoolStart[s->n_strx()];
if ( symName > mergedStringPoolEnd )
symName = "<corrupt symbol name>";
strcpy(&newStringPoolStart[poolOffset], symName);
poolOffset += (strlen(symName) + 1);
++t;
++symbolsCopied;
}
// <rdar://problem/16529213> recreate N_INDR symbols in extracted dylibs for debugger
for (std::vector<mach_o::trie::Entry>::iterator it = exports.begin(); it != exports.end(); ++it) {
strcpy(&newStringPoolStart[poolOffset], it->name);
t->set_n_strx(poolOffset);
poolOffset += (strlen(it->name) + 1);
t->set_n_type(N_INDR | N_EXT);
t->set_n_sect(0);
t->set_n_desc(0);
const char* importName = it->importName;
if ( *importName == '\0' )
importName = it->name;
strcpy(&newStringPoolStart[poolOffset], importName);
t->set_n_value(poolOffset);
poolOffset += (strlen(importName) + 1);
++t;
++symbolsCopied;
}
if ( localNlists != NULL ) {
// update load command to reflect new count of locals
dynamicSymTab->set_ilocalsym(symbolsCopied);
dynamicSymTab->set_nlocalsym(localNlistCount);
// copy local symbols
for (uint32_t i=0; i < localNlistCount; ++i) {
const char* localName = &localStrings[localNlists[i].n_strx()];
if ( localName > localStringsEnd )
localName = "<corrupt local symbol name>";
*t = localNlists[i];
t->set_n_strx(poolOffset);
strcpy(&newStringPoolStart[poolOffset], localName);
poolOffset += (strlen(localName) + 1);
++t;
++symbolsCopied;
}
}
if ( newSymCount != symbolsCopied ) {
fprintf(stderr, "symbol count miscalculation\n");
return -1;
}
// pointer align string pool size
while ( (poolOffset % sizeof(pint_t)) != 0 )
++poolOffset;
// copy indirect symbol table
uint32_t* newIndSymTab = (uint32_t*)((char*)mh + newIndSymTabOffset);
memcpy(newIndSymTab, mergedIndSymTab, dynamicSymTab->nindirectsyms()*sizeof(uint32_t));
// update load commands
if ( functionStarts != NULL ) {
functionStarts->set_dataoff((uint32_t)newFunctionStartsOffset);
functionStarts->set_datasize(functionStartsSize);
}
if ( dataInCode != NULL ) {
dataInCode->set_dataoff((uint32_t)newDataInCodeOffset);
dataInCode->set_datasize(dataInCodeSize);
}
symtab->set_nsyms(symbolsCopied);
symtab->set_symoff((uint32_t)newSymTabOffset);
symtab->set_stroff((uint32_t)newStringPoolOffset);
symtab->set_strsize(poolOffset);
dynamicSymTab->set_extreloff(0);
dynamicSymTab->set_nextrel(0);
dynamicSymTab->set_locreloff(0);
dynamicSymTab->set_nlocrel(0);
dynamicSymTab->set_indirectsymoff((uint32_t)newIndSymTabOffset);
linkEditSegCmd->set_filesize(symtab->stroff()+symtab->strsize() - linkEditSegCmd->fileoff());
linkEditSegCmd->set_vmsize( (linkEditSegCmd->filesize()+4095) & (-4096) );
// return new size
*newSize = (symtab->stroff()+symtab->strsize()+4095) & (-4096);
linkEditSegCmd->set_filesize(*newSize - linkEditSegCmd->fileoff());
symtab->set_strsize(*newSize - symtab->stroff());
fixupObjc<A>(mh, textOffsetInCache, mapped_cache);
// <rdar://problem/17671438> Xcode 6 leaks in dyld_shared_cache_extract_dylibs
for (std::vector<mach_o::trie::Entry>::iterator it = exports.begin(); it != exports.end(); ++it) {
::free((void*)(it->name));
}
return 0;
}
static void make_dirs(const char* file_path)
{
//printf("make_dirs(%s)\n", file_path);
char dirs[strlen(file_path)+1];
strcpy(dirs, file_path);
char* lastSlash = strrchr(dirs, '/');
if ( lastSlash == NULL )
return;
lastSlash[1] = '\0';
struct stat stat_buf;
if ( stat(dirs, &stat_buf) != 0 ) {
char* afterSlash = &dirs[1];
char* slash;
while ( (slash = strchr(afterSlash, '/')) != NULL ) {
*slash = '\0';
::mkdir(dirs, S_IRWXU | S_IRGRP|S_IXGRP | S_IROTH|S_IXOTH);
//printf("mkdir(%s)\n", dirs);
*slash = '/';
afterSlash = slash+1;
}
}
}
template <typename A>
size_t dylib_maker(const void* mapped_cache, std::vector<uint8_t> &dylib_data, const std::vector<seg_info>& segments) {
typedef typename A::P P;
size_t additionalSize = 0;
for(std::vector<seg_info>::const_iterator it=segments.begin(); it != segments.end(); ++it) {
additionalSize += it->sizem;
}
dylib_data.reserve(dylib_data.size() + additionalSize);
uint32_t nfat_archs = 0;
uint32_t offsetInFatFile = 4096;
uint8_t *base_ptr = &dylib_data.front();
#define FH reinterpret_cast<fat_header*>(base_ptr)
#define FA reinterpret_cast<fat_arch*>(base_ptr + (8 + (nfat_archs - 1) * sizeof(fat_arch)))
if(dylib_data.size() >= 4096 && OSSwapBigToHostInt32(FH->magic) == FAT_MAGIC) {
// have fat header, append new arch to end
nfat_archs = OSSwapBigToHostInt32(FH->nfat_arch);
offsetInFatFile = OSSwapBigToHostInt32(FA->offset) + OSSwapBigToHostInt32(FA->size);
}
dylib_data.resize(offsetInFatFile);
base_ptr = &dylib_data.front();
FH->magic = OSSwapHostToBigInt32(FAT_MAGIC);
FH->nfat_arch = OSSwapHostToBigInt32(++nfat_archs);
FA->cputype = 0; // filled in later
FA->cpusubtype = 0; // filled in later
FA->offset = OSSwapHostToBigInt32(offsetInFatFile);
FA->size = 0; // filled in later
FA->align = OSSwapHostToBigInt32(12);
// Write regular segments into the buffer
uint64_t totalSize = 0;
uint64_t textOffsetInCache = 0;
for( std::vector<seg_info>::const_iterator it=segments.begin(); it != segments.end(); ++it) {