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darling/mach-o.cc
Shinichiro Hamaji aab7695671 Don't read exported symbols of executables
2011-03-28 20:34:15 +09:00

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// Copyright 2011 Shinichiro Hamaji. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials
// provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY Shinichiro Hamaji ``AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL Shinichiro Hamaji OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
// USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "fat.h"
#include "log.h"
#include "mach-o.h"
#include "mach-o/loader.h"
DEFINE_bool(READ_SYMTAB, true, "Read symtab for better backtrace");
DEFINE_bool(READ_DYSYMTAB, false, "Read dysymtab");
typedef long long ll;
typedef unsigned long long ull;
struct sym {
uint32_t name;
uint32_t addr;
uint32_t flag;
};
struct sym64 {
uint32_t name;
uint64_t addr;
uint32_t flag;
};
static uint64_t uleb128(const uint8_t*& p) {
uint64_t r = 0;
int s = 0;
for (;;) {
uint8_t b = *p++;
if (b < 0x80) {
r += b << s;
break;
}
r += (b & 0x7f) << s;
s += 7;
}
return r;
}
static int64_t sleb128(const uint8_t*& p) {
int64_t r = 0;
int s = 0;
for (;;) {
uint8_t b = *p++;
if (b < 0x80) {
if (b & 0x40) {
r -= (0x80 - b) << s;
}
else {
r += (b & 0x3f) << s;
}
break;
}
r += (b & 0x7f) << s;
s += 7;
}
return r;
}
struct MachO::RebaseState {
explicit RebaseState(MachO* mach0)
: mach(mach0), type(0), seg_index(0), seg_offset(0) {}
bool readRebaseOp(const uint8_t*& p) {
uint8_t op = *p & REBASE_OPCODE_MASK;
uint8_t imm = *p & REBASE_IMMEDIATE_MASK;
p++;
switch (op) {
case REBASE_OPCODE_DONE:
return false;
case REBASE_OPCODE_SET_TYPE_IMM:
type = imm;
break;
case REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
seg_index = imm;
seg_offset = uleb128(p);
break;
case REBASE_OPCODE_ADD_ADDR_ULEB:
seg_offset += uleb128(p);
break;
case REBASE_OPCODE_ADD_ADDR_IMM_SCALED:
seg_offset += imm * mach->ptrsize_;
break;
case REBASE_OPCODE_DO_REBASE_IMM_TIMES:
for (int i = 0; i < imm; i++) {
addRebase();
}
break;
case REBASE_OPCODE_DO_REBASE_ULEB_TIMES: {
int count = uleb128(p);
for (int i = 0; i < count; i++) {
addRebase();
}
break;
}
case REBASE_OPCODE_DO_REBASE_ADD_ADDR_ULEB:
addRebase();
seg_offset += uleb128(p);
break;
case REBASE_OPCODE_DO_REBASE_ULEB_TIMES_SKIPPING_ULEB: {
int count = uleb128(p);
uint64_t skip = uleb128(p);
for (int i = 0; i < count; i++) {
addRebase();
seg_offset += skip;
}
break;
}
default:
fprintf(stderr, "unknown op: %x\n", op);
}
return true;
}
void addRebase() {
MachO::Rebase* rebase = new MachO::Rebase();
uint64_t vmaddr;
if (mach->is64_) {
vmaddr = mach->segments64_[seg_index]->vmaddr;
} else {
vmaddr = mach->segments_[seg_index]->vmaddr;
}
LOGF("add rebase! seg_index=%d seg_offset=%llu type=%d vmaddr=%p\n",
seg_index, (ull)seg_offset, type, (void*)vmaddr);
rebase->vmaddr = vmaddr + seg_offset;
rebase->type = type;
mach->rebases_.push_back(rebase);
seg_offset += mach->ptrsize_;
}
MachO* mach;
uint8_t type;
int seg_index;
uint64_t seg_offset;
};
void MachO::readRebase(const uint8_t* p, const uint8_t* end) {
RebaseState state(this);
while (p < end) {
if (!state.readRebaseOp(p))
break;
}
}
struct MachO::BindState {
explicit BindState(MachO* mach0)
: mach(mach0), ordinal(0), sym_name(NULL), type(BIND_TYPE_POINTER),
addend(0), seg_index(0), seg_offset(0) {}
void readBindOp(const uint8_t*& p) {
uint8_t op = *p & BIND_OPCODE_MASK;
uint8_t imm = *p & BIND_IMMEDIATE_MASK;
p++;
LOGF("bind: op=%x imm=%d\n", op, imm);
switch (op) {
case BIND_OPCODE_DONE:
break;
case BIND_OPCODE_SET_DYLIB_ORDINAL_IMM:
ordinal = imm;
break;
case BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB:
ordinal = uleb128(p);
break;
case BIND_OPCODE_SET_DYLIB_SPECIAL_IMM:
if (imm == 0) {
ordinal = 0;
} else {
ordinal = BIND_OPCODE_MASK | imm;
}
break;
case BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
sym_name = reinterpret_cast<const char*>(p);
p += strlen(sym_name) + 1;
LOGF("sym_name=%s\n", sym_name);
break;
case BIND_OPCODE_SET_TYPE_IMM:
type = imm;
break;
case BIND_OPCODE_SET_ADDEND_SLEB:
addend = sleb128(p);
break;
case BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
seg_index = imm;
seg_offset = uleb128(p);
break;
case BIND_OPCODE_ADD_ADDR_ULEB:
seg_offset += uleb128(p);
break;
case BIND_OPCODE_DO_BIND:
addBind();
break;
case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
LOGF("BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB\n");
addBind();
seg_offset += uleb128(p);
break;
case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
LOGF("BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED %d\n", (int)imm);
addBind();
seg_offset += imm * mach->ptrsize_;
break;
case BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB: {
uint64_t count = uleb128(p);
uint64_t skip = uleb128(p);
LOGF("BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB %u %u\n",
(unsigned)count, (unsigned)skip);
for (uint64_t i = 0; i < count; i++) {
addBind();
seg_offset += skip;
}
break;
}
default:
fprintf(stderr, "unknown op: %x\n", op);
}
}
void addBind() {
MachO::Bind* bind = new MachO::Bind();
uint64_t vmaddr;
if (mach->is64_) {
vmaddr = mach->segments64_[seg_index]->vmaddr;
} else {
vmaddr = mach->segments_[seg_index]->vmaddr;
}
LOGF("add bind! %s seg_index=%d seg_offset=%llu "
"type=%d ordinal=%d addend=%lld vmaddr=%p\n",
sym_name, seg_index, (ull)seg_offset,
type, ordinal, (ll)addend, (void*)vmaddr);
bind->name = sym_name;
bind->vmaddr = vmaddr + seg_offset;
bind->addend = addend;
bind->type = type;
bind->ordinal = ordinal;
mach->binds_.push_back(bind);
seg_offset += mach->ptrsize_;
}
MachO* mach;
uint8_t ordinal;
const char* sym_name;
uint8_t type;
int64_t addend;
int seg_index;
uint64_t seg_offset;
};
void MachO::readBind(const uint8_t* p, const uint8_t* end) {
BindState state(this);
while (p < end) {
state.readBindOp(p);
}
}
void MachO::readExport(const uint8_t* start,
const uint8_t* p,
const uint8_t* end,
string* name_buf) {
LOGF("readExport: %p-%p\n", p, end);
#if 0
char buf[17];
buf[16] = '\0';
for (int i = 0; i < 16*8; i++) {
LOGF("%02x ", p[i]);
buf[i % 16] = p[i] < 32 ? '?' : p[i];
if (i % 16 == 15) LOGF("%s\n", buf);
}
#endif
if (p >= end) {
fprintf(stderr, "broken export trie\n");
exit(1);
}
if (uint8_t term_size = *p++) {
const uint8_t* expected_term_end = p + term_size;
Export exp;
exp.name = *name_buf;
exp.flag = uleb128(p);
exp.addr = uleb128(p);
LOGF("export: %s %lu %p\n",
name_buf->c_str(), (long)exp.flag, (void*)exp.addr);
exports_.push_back(exp);
assert(expected_term_end == p);
}
const uint8_t num_children = *p++;
for (uint8_t i = 0; i < num_children; i++) {
size_t orig_name_size = name_buf->size();
while (*p) {
name_buf->push_back(*p++);
}
p++;
uint64_t off = uleb128(p);
assert(off != 0);
readExport(start, start + off, end, name_buf);
name_buf->resize(orig_name_size);
}
}
MachO::MachO(const char* filename)
: filename_(filename), need_exports_(true) {
int fd = open(filename, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "open %s: %s\n", filename, strerror(errno));
exit(1);
}
init(fd, 0, 0);
}
MachO::MachO(const char* filename, int fd, size_t offset, size_t len,
bool need_exports)
: filename_(filename), need_exports_(need_exports) {
lseek(fd, 0, SEEK_SET);
init(fd, offset, len);
}
void MachO::init(int fd, size_t offset, size_t len) {
assert(fd);
fd_ = fd;
offset_ = offset;
if (!len) {
len = lseek(fd_, 0, SEEK_END);
}
char* bin = reinterpret_cast<char*>(
mmap(NULL, len,
PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd_, offset));
base_ = bin;
mach_header* header = reinterpret_cast<mach_header*>(bin);
LOGF("magic=%x cpu=%d cpusub=%d file=%d ncmds=%d sizecmd=%d flags=%x\n",
header->magic, header->cputype, header->cpusubtype,
header->filetype, header->ncmds, header->sizeofcmds,
header->flags);
is64_ = false;
if (header->magic == MH_MAGIC_64) {
is64_ = true;
} else if (header->magic != MH_MAGIC) {
fprintf(stderr, "Not mach-o\n");
exit(1);
}
ptrsize_ = is64_ ? 8 : 4;
if ((header->cputype & 0x00ffffff) != CPU_TYPE_X86) {
fprintf(stderr, "Unsupported CPU\n");
exit(1);
}
char* cmds_ptr = bin + sizeof(mach_header);
if (is64_) {
cmds_ptr += sizeof(uint32_t);
}
uint32_t* symtab = NULL;
const char* symstrtab = NULL;
for (uint32_t i = 0; i < header->ncmds; i++) {
uint32_t cmd = *reinterpret_cast<uint32_t*>(cmds_ptr);
LOGF("%x\n", cmd);
switch (cmd) {
case LC_SEGMENT_64: {
segment_command_64* segment =
reinterpret_cast<segment_command_64*>(cmds_ptr);
segments64_.push_back(segment);
LOGF("segment %s: vmaddr=%p vmsize=%llu "
"fileoff=%llu filesize=%llu "
"maxprot=%d initprot=%d nsects=%u flags=%u\n",
segment->segname,
(void*)segment->vmaddr, (ull)segment->vmsize,
(ull)segment->fileoff, (ull)segment->filesize,
segment->maxprot, segment->initprot,
segment->nsects, segment->flags);
section_64* sections = reinterpret_cast<section_64*>(
cmds_ptr + sizeof(segment_command_64));
for (uint32_t j = 0; j < segment->nsects; j++) {
const section_64& sec = sections[j];
LOGF("section %s in %s: "
"addr=%p size=%llu offset=%u align=%u "
"reloff=%u nreloc=%u flags=%u "
"reserved1=%u reserved2=%u reserved3=%u\n",
sec.sectname, sec.segname,
(void*)sec.addr, (ull)sec.size,
sec.offset, sec.align,
sec.reloff, sec.nreloc, sec.flags,
sec.reserved1, sec.reserved2, sec.reserved3);
int section_type = sec.flags & SECTION_TYPE;
if (section_type == S_MOD_INIT_FUNC_POINTERS) {
for (uint64_t p = sec.addr;
p < sec.addr + sec.size;
p += ptrsize_) {
init_funcs_.push_back(p);
}
}
// TODO(hamaji): Support term_funcs.
}
break;
}
case LC_DYLD_INFO_ONLY: {
dyld_info_command* dyinfo =
reinterpret_cast<dyld_info_command*>(cmds_ptr);
LOGF("dyld info: rebase_off=%u rebase_size=%u "
"bind_off=%u bind_size=%u "
"weak_bind_off=%u weak_bind_size=%u "
"lazy_bind_off=%u lazy_bind_size=%u "
"export_off=%u export_size=%u\n",
dyinfo->rebase_off, dyinfo->rebase_size,
dyinfo->bind_off, dyinfo->bind_size,
dyinfo->weak_bind_off, dyinfo->weak_bind_size,
dyinfo->lazy_bind_off, dyinfo->lazy_bind_size,
dyinfo->export_off, dyinfo->export_size);
{
const uint8_t* p = reinterpret_cast<uint8_t*>(
bin + dyinfo->rebase_off);
const uint8_t* end = p + dyinfo->rebase_size;
if (dyinfo->rebase_off && dyinfo->rebase_size) {
readRebase(p, end);
}
}
{
const uint8_t* p = reinterpret_cast<uint8_t*>(
bin + dyinfo->bind_off);
const uint8_t* end = p + dyinfo->bind_size;
readBind(p, end);
}
{
const uint8_t* p = reinterpret_cast<uint8_t*>(
bin + dyinfo->lazy_bind_off);
const uint8_t* end = p + dyinfo->lazy_bind_size;
readBind(p, end);
}
if (need_exports_) {
const uint8_t* p = reinterpret_cast<uint8_t*>(
bin + dyinfo->export_off);
const uint8_t* end = p + dyinfo->export_size;
if (dyinfo->export_off && dyinfo->export_size) {
string buf;
readExport(p, p, end, &buf);
}
}
break;
}
case LC_SYMTAB: {
symtab_command* symtab_cmd =
reinterpret_cast<symtab_command*>(cmds_ptr);
LOGF("symoff=%u nsysm=%u stroff=%u strsize=%u\n",
symtab_cmd->symoff, symtab_cmd->nsyms,
symtab_cmd->stroff, symtab_cmd->strsize);
uint32_t* symtab_top = symtab =
reinterpret_cast<uint32_t*>(bin + symtab_cmd->symoff);
symstrtab = bin + symtab_cmd->stroff;
if (FLAGS_READ_SYMTAB) {
for (uint32_t i = 0; i < symtab_cmd->nsyms; i++) {
Symbol sym;
if (is64_) {
sym.name = symstrtab + symtab[0];
sym.addr = *(uint64_t*)(symtab + 2);
LOGF("%d %s(%d) %p %d\n",
i, sym.name.c_str(), symtab[0], (void*)sym.addr,
symtab[3]);
symtab += 4;
} else {
sym.name = symstrtab + symtab[0];
sym.addr = (uint64_t)*(uint32_t*)(symtab + 1);
LOGF("%d %s(%d) %p %d\n",
i, sym.name.c_str(), symtab[0], (void*)sym.addr,
symtab[2]);
symtab += 3;
}
symbols_.push_back(sym);
}
}
// Will be used by other load commands.
symtab = symtab_top;
break;
}
case LC_DYSYMTAB: {
dysymtab_command* dysymtab_cmd =
reinterpret_cast<dysymtab_command*>(cmds_ptr);
LOGF("dysym:\n"
" ilocalsym=%u nlocalsym=%u\n"
" iextdefsym=%u nextdefsym=%u\n"
" iundefsym=%u nundefsym=%u\n"
" tocoff=%u ntoc=%u\n"
" modtaboff=%u nmodtab=%u\n"
" extrefsymoff=%u nextrefsyms=%u\n"
" indirectsymoff=%u nindirectsyms=%u\n"
" extreloff=%u nextrel=%u\n"
" locreloff=%u nlocrel=%u\n"
,
dysymtab_cmd->ilocalsym, dysymtab_cmd->nlocalsym,
dysymtab_cmd->iextdefsym, dysymtab_cmd->nextdefsym,
dysymtab_cmd->iundefsym, dysymtab_cmd->nundefsym,
dysymtab_cmd->tocoff, dysymtab_cmd->ntoc,
dysymtab_cmd->modtaboff, dysymtab_cmd->nmodtab,
dysymtab_cmd->extrefsymoff, dysymtab_cmd->nextrefsyms,
dysymtab_cmd->indirectsymoff, dysymtab_cmd->nindirectsyms,
dysymtab_cmd->extreloff, dysymtab_cmd->nextrel,
dysymtab_cmd->locreloff, dysymtab_cmd->nlocrel);
if (FLAGS_READ_DYSYMTAB) {
uint32_t* dysyms = reinterpret_cast<uint32_t*>(
bin + dysymtab_cmd->indirectsymoff);
for (uint32_t j = 0; j < dysymtab_cmd->nindirectsyms; j++) {
uint32_t dysym = dysyms[j];
uint32_t index = dysym & 0x3fffffff;
const char* local =
(dysym & INDIRECT_SYMBOL_LOCAL) ? " local" : "";
const char* abs =
(dysym & INDIRECT_SYMBOL_ABS) ? " abs" : "";
uint32_t* sym = symtab;
sym += index * (is64_ ? 4 : 3);
LOGF("dysym %d %s(%u)%s%s\n",
j, symstrtab + sym[0], index, local, abs);
}
uint32_t* dymods = reinterpret_cast<uint32_t*>(
bin + dysymtab_cmd->modtaboff);
for (uint32_t j = 0; j < dysymtab_cmd->nmodtab; j++) {
LOGF("dymods: %u\n", dymods[j]);
}
}
break;
}
case LC_LOAD_DYLINKER: {
lc_str name = *reinterpret_cast<lc_str*>(
cmds_ptr + sizeof(uint32_t) * 2);
LOGF("dylinker: %s\n", cmds_ptr + name.offset);
break;
}
case LC_UUID:
break;
case LC_UNIXTHREAD: {
uint32_t* p = reinterpret_cast<uint32_t*>(cmds_ptr);
LOGF("UNIXTHREAD");
for (uint32_t i = 2; i < p[1]; i++) {
LOGF(" %d:%x", i, p[i]);
}
LOGF("\n");
entry_ = reinterpret_cast<uint64_t*>(cmds_ptr)[18];
LOGF("entry=%llx\n", (ull)entry_);
break;
}
case LC_LOAD_DYLIB: {
dylib* lib = reinterpret_cast<dylib*>(cmds_ptr + sizeof(uint32_t) * 2);
LOGF("dylib: %s\n", cmds_ptr + lib->name.offset);
dylibs_.push_back(cmds_ptr + lib->name.offset);
break;
}
}
cmds_ptr += reinterpret_cast<uint32_t*>(cmds_ptr)[1];
}
LOGF("%p vs %p\n", cmds_ptr, bin + len);
}
MachO::~MachO() {
for (size_t i = 0; i < binds_.size(); i++) {
delete binds_[i];
}
// need munmap
close(fd_);
}
MachO* readMachO(const char* path, const char* arch, bool need_exports) {
int fd = open(path, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "%s: %s\n", path, strerror(errno));
exit(1);
}
size_t offset = 0, len = 0;
map<string, fat_arch> archs;
if (readFatInfo(fd, &archs)) {
map<string, fat_arch>::const_iterator found = archs.find(arch);
if (found == archs.end()) {
fprintf(stderr,
"%s is a fat binary, but doesn't contain %s binary\n",
path, arch);
exit(1);
}
offset = found->second.offset;
len = found->second.size;
LOGF("fat offset=%lu, len=%lu\n", offset, len);
}
return new MachO(path, fd, offset, len, need_exports);
}
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