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plthook_osx.c
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/* -*- indent-tabs-mode: nil -*-
*
* plthook_osx.c -- implementation of plthook for OS X
*
* URL: https://github.com/kubo/plthook
*
* ------------------------------------------------------
*
* Copyright 2014-2024 Kubo Takehiro <kubo@jiubao.org>
*
* 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 THE AUTHORS ''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 <COPYRIGHT HOLDER> 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.
*
* The views and conclusions contained in the software and documentation are those of the
* authors and should not be interpreted as representing official policies, either expressed
* or implied, of the authors.
*
*/
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>
#include <dlfcn.h>
#include <errno.h>
#include <mach/mach.h>
#include <mach-o/dyld.h>
#include <sys/mman.h>
#include <mach-o/fixup-chains.h>
#include "plthook.h"
#ifdef PLTHOOK_DEBUG
#define PLTHOOK_DEBUG_CMD 1
#define PLTHOOK_DEBUG_BIND 1
#define PLTHOOK_DEBUG_FIXUPS 1
#define PLTHOOK_DEBUG_ADDR 1
#endif
#ifdef PLTHOOK_DEBUG_CMD
#define DEBUG_CMD(...) fprintf(stderr, __VA_ARGS__)
#else
#define DEBUG_CMD(...)
#endif
#ifdef PLTHOOK_DEBUG_FIXUPS
#define DEBUG_FIXUPS(...) fprintf(stderr, __VA_ARGS__)
#else
#define DEBUG_FIXUPS(...)
#endif
#ifdef PLTHOOK_DEBUG_BIND
#define DEBUG_BIND(...) fprintf(stderr, __VA_ARGS__)
#define DEBUG_BIND_IF(cond, ...) if (cond) fprintf(stderr, __VA_ARGS__)
#else
#define DEBUG_BIND(...)
#define DEBUG_BIND_IF(cond, ...)
#endif
#ifdef PLTHOOK_DEBUG_ADDR
#include <mach/mach.h>
#define INHERIT_MAX_SIZE 11
static char *inherit_to_str(vm_inherit_t inherit, char *buf)
{
switch (inherit) {
case VM_INHERIT_SHARE: return "share";
case VM_INHERIT_COPY: return "copy";
case VM_INHERIT_NONE: return "none";
case VM_INHERIT_DONATE_COPY: return "donate_copy";
default:
sprintf(buf, "%d", inherit);
return buf;
}
}
#define BEHAVIOR_MAX_SIZE 16
static char *behavior_to_str(vm_behavior_t behavior, char *buf)
{
switch (behavior) {
case VM_BEHAVIOR_DEFAULT: return "default";
case VM_BEHAVIOR_RANDOM: return "random";
case VM_BEHAVIOR_SEQUENTIAL: return "sequential";
case VM_BEHAVIOR_RSEQNTL: return "rseqntl";
case VM_BEHAVIOR_WILLNEED: return "willneed";
case VM_BEHAVIOR_DONTNEED: return "dontneed";
case VM_BEHAVIOR_FREE: return "free";
case VM_BEHAVIOR_ZERO_WIRED_PAGES: return "zero";
case VM_BEHAVIOR_REUSABLE: return "reusable";
case VM_BEHAVIOR_REUSE: return "reuse";
case VM_BEHAVIOR_CAN_REUSE: return "can";
case VM_BEHAVIOR_PAGEOUT: return "pageout";
default:
sprintf(buf, "%d", behavior);
return buf;
}
}
static void dump_maps(const char *image_name)
{
mach_port_t task = mach_task_self();
vm_region_basic_info_data_64_t info;
mach_msg_type_number_t info_count = VM_REGION_BASIC_INFO_COUNT_64;
memory_object_name_t object = 0;
vm_address_t addr = 0;
vm_size_t size;
char inherit_buf[INHERIT_MAX_SIZE + 1];
char behavior_buf[BEHAVIOR_MAX_SIZE + 1];
fprintf(stderr, "MEMORY MAP(%s)\n", image_name);
fprintf(stderr, " start address end address protection max_protection inherit shared reserved offset behavior user_wired_count\n");
while (vm_region_64(task, &addr, &size, VM_REGION_BASIC_INFO_64, (vm_region_info_t)&info, &info_count, &object) == KERN_SUCCESS) {
fprintf(stderr, " %016lx-%016lx %c%c%c(%08x) %c%c%c(%08x) %-*s %c %c %08llx %-*s %u\n",
addr, addr + size,
(info.protection & VM_PROT_READ) ? 'r' : '-',
(info.protection & VM_PROT_WRITE) ? 'w' : '-',
(info.protection & VM_PROT_EXECUTE) ? 'x' : '-',
info.protection,
(info.max_protection & VM_PROT_READ) ? 'r' : '-',
(info.max_protection & VM_PROT_WRITE) ? 'w' : '-',
(info.max_protection & VM_PROT_EXECUTE) ? 'x' : '-',
info.max_protection,
INHERIT_MAX_SIZE, inherit_to_str(info.inheritance, inherit_buf),
info.shared ? 'Y' : 'N',
info.reserved ? 'Y' : 'N',
info.offset,
BEHAVIOR_MAX_SIZE, behavior_to_str(info.behavior, behavior_buf),
info.user_wired_count);
addr += size;
}
}
#endif
typedef struct {
const char *name;
int addend;
char weak;
void **addr;
} bind_address_t;
typedef struct mem_prot {
size_t start;
size_t end;
int prot;
} mem_prot_t;
#define NUM_MEM_PROT 100
struct plthook {
unsigned int num_entries;
mem_prot_t mem_prot[NUM_MEM_PROT];
bind_address_t entries[1]; /* This must be the last. */
};
#define MAX_SEGMENTS 8
#define MAX_SECTIONS 30
typedef struct {
plthook_t *plthook;
intptr_t slide;
int num_segments;
int linkedit_segment_idx;
const struct segment_command_64 *segments[MAX_SEGMENTS];
#ifdef PLTHOOK_DEBUG_FIXUPS
int num_sections;
const struct section_64 *sections[MAX_SECTIONS];
#endif
const struct linkedit_data_command *chained_fixups;
} data_t;
static int plthook_open_real(plthook_t **plthook_out, uint32_t image_idx, const struct mach_header *mh, const char *image_name);
static unsigned int set_bind_addrs(data_t *data, unsigned int idx, uint32_t bind_off, uint32_t bind_size, char weak);
static void set_bind_addr(data_t *d, unsigned int *idx, const char *sym_name, int seg_index, int seg_offset, int addend, char weak);
static int read_chained_fixups(data_t *d, const char *image_name);
#ifdef PLTHOOK_DEBUG_FIXUPS
static const char *segment_name_from_addr(data_t *d, size_t addr);
static const char *section_name_from_addr(data_t *d, size_t addr);
#endif
static int set_mem_prot(plthook_t *plthook);
static int get_mem_prot(plthook_t *plthook, void *addr);
static inline uint8_t *fileoff_to_vmaddr_in_segment(data_t *d, int segment_index, size_t offset)
{
const struct segment_command_64 *seg = d->segments[segment_index];
return (uint8_t *)(seg->vmaddr - seg->fileoff + d->slide + offset);
}
static uint8_t *fileoff_to_vmaddr(data_t *data, size_t offset);
static void set_errmsg(const char *fmt, ...) __attribute__((__format__ (__printf__, 1, 2)));
static uint64_t uleb128(const uint8_t **p)
{
uint64_t r = 0;
int s = 0;
do {
r |= (uint64_t)(**p & 0x7f) << s;
s += 7;
} while (*(*p)++ >= 0x80);
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;
}
static char errmsg[512];
int plthook_open(plthook_t **plthook_out, const char *filename)
{
size_t namelen;
uint32_t cnt;
uint32_t idx;
if (filename == NULL) {
return plthook_open_real(plthook_out, 0, NULL, NULL);
}
cnt = _dyld_image_count();
namelen = strlen(filename);
for (idx = 0; idx < cnt; idx++) {
const char *image_name = _dyld_get_image_name(idx);
size_t offset = 0;
if (image_name == NULL) {
*plthook_out = NULL;
set_errmsg("Cannot find file at image index %u", idx);
return PLTHOOK_INTERNAL_ERROR;
}
if (*filename != '/') {
size_t image_name_len = strlen(image_name);
if (image_name_len > namelen) {
offset = image_name_len - namelen;
}
}
if (strcmp(image_name + offset, filename) == 0) {
return plthook_open_real(plthook_out, idx, NULL, image_name);
}
}
*plthook_out = NULL;
set_errmsg("Cannot find file: %s", filename);
return PLTHOOK_FILE_NOT_FOUND;
}
int plthook_open_by_handle(plthook_t **plthook_out, void *hndl)
{
int flags[] = {
RTLD_LAZY | RTLD_NOLOAD,
RTLD_LAZY | RTLD_NOLOAD | RTLD_FIRST,
};
int flag_idx;
uint32_t cnt = _dyld_image_count();
#define NUM_FLAGS (sizeof(flags) / sizeof(flags[0]))
if (hndl == NULL) {
set_errmsg("NULL handle");
return PLTHOOK_FILE_NOT_FOUND;
}
for (flag_idx = 0; flag_idx < (int)NUM_FLAGS; flag_idx++) {
uint32_t idx;
for (idx = 0; idx < cnt; idx++) {
const char *image_name = idx ? _dyld_get_image_name(idx) : NULL;
void *handle = dlopen(image_name, flags[flag_idx]);
if (handle != NULL) {
dlclose(handle);
if (handle == hndl) {
return plthook_open_real(plthook_out, idx, NULL, image_name);
}
}
}
}
set_errmsg("Cannot find the image correspond to handle %p", hndl);
return PLTHOOK_FILE_NOT_FOUND;
}
int plthook_open_by_address(plthook_t **plthook_out, void *address)
{
Dl_info dlinfo;
uint32_t idx = 0;
uint32_t cnt = _dyld_image_count();
if (!dladdr(address, &dlinfo)) {
*plthook_out = NULL;
set_errmsg("Cannot find address: %p", address);
return PLTHOOK_FILE_NOT_FOUND;
}
for (idx = 0; idx < cnt; idx++) {
if (dlinfo.dli_fbase == _dyld_get_image_header(idx)) {
return plthook_open_real(plthook_out, idx, dlinfo.dli_fbase, dlinfo.dli_fname);
}
}
set_errmsg("Cannot find the image index for base address: %p", dlinfo.dli_fbase);
return PLTHOOK_FILE_NOT_FOUND;
}
static int plthook_open_real(plthook_t **plthook_out, uint32_t image_idx, const struct mach_header *mh, const char *image_name)
{
struct load_command *cmd;
const struct dyld_info_command *dyld_info = NULL;
unsigned int nbind;
data_t data;
size_t size;
uint32_t i;
memset(&data, 0, sizeof(data_t));
data.linkedit_segment_idx = -1;
data.slide = _dyld_get_image_vmaddr_slide(image_idx);
if (mh == NULL) {
mh = _dyld_get_image_header(image_idx);
}
if (image_name == NULL) {
image_name = _dyld_get_image_name(image_idx);
}
#if defined(PLTHOOK_DEBUG_CMD) || defined(PLTHOOK_DEBUG_ADDR)
fprintf(stderr, "mh=%"PRIxPTR" slide=%"PRIxPTR"\n", (uintptr_t)mh, data.slide);
#endif
#ifdef PLTHOOK_DEBUG_ADDR
dump_maps(image_name);
#endif
cmd = (struct load_command *)((size_t)mh + sizeof(struct mach_header_64));
DEBUG_CMD("CMD START\n");
for (i = 0; i < mh->ncmds; i++) {
#ifdef PLTHOOK_DEBUG_CMD
struct segment_command *segment;
#endif
struct segment_command_64 *segment64;
switch (cmd->cmd) {
case LC_SEGMENT: /* 0x1 */
#ifdef PLTHOOK_DEBUG_CMD
segment = (struct segment_command *)cmd;
#endif
DEBUG_CMD("LC_SEGMENT\n"
" segname %s\n"
" vmaddr %8x vmsize %8x\n"
" fileoff %8x filesize %8x\n"
" maxprot %8x initprot %8x\n"
" nsects %8d flags %8x\n",
segment->segname,
segment->vmaddr, segment->vmsize,
segment->fileoff, segment->filesize,
segment->maxprot, segment->initprot,
segment->nsects, segment->flags);
break;
case LC_SEGMENT_64: /* 0x19 */
segment64 = (struct segment_command_64 *)cmd;
DEBUG_CMD("LC_SEGMENT_64\n"
" segname %s\n"
" vmaddr %8llx vmsize %8llx\n"
" fileoff %8llx filesize %8llx\n"
" maxprot %8x initprot %8x\n"
" nsects %8d flags %8x\n",
segment64->segname,
segment64->vmaddr, segment64->vmsize,
segment64->fileoff, segment64->filesize,
segment64->maxprot, segment64->initprot,
segment64->nsects, segment64->flags);
if (strcmp(segment64->segname, "__LINKEDIT") == 0) {
data.linkedit_segment_idx = data.num_segments;
}
#ifdef PLTHOOK_DEBUG_FIXUPS
struct section_64 *sec = (struct section_64 *)(segment64 + 1);
uint32_t i;
for (i = 0; i < segment64->nsects; i++) {
DEBUG_CMD(" section_64 (%u)\n"
" sectname %s\n"
" segname %s\n"
" addr 0x%llx\n"
" size 0x%llx\n"
" offset 0x%x\n"
" align 0x%x\n"
" reloff 0x%x\n"
" nreloc %d\n"
" flags 0x%x\n"
" reserved1 %d\n"
" reserved2 %d\n"
" reserved3 %d\n",
i,
sec->sectname,
sec->segname,
sec->addr,
sec->size,
sec->offset,
sec->align,
sec->reloff,
sec->nreloc,
sec->flags,
sec->reserved1,
sec->reserved2,
sec->reserved3);
sec++;
}
#endif
if (data.num_segments == MAX_SEGMENTS) {
set_errmsg("Too many segments: %s", image_name);
return PLTHOOK_INTERNAL_ERROR;
}
data.segments[data.num_segments++] = segment64;
#ifdef PLTHOOK_DEBUG_FIXUPS
{
struct section_64 *sec = (struct section_64 *)(segment64 + 1);
struct section_64 *sec_end = sec + segment64->nsects;
while (sec < sec_end) {
if (data.num_sections == MAX_SECTIONS) {
set_errmsg("Too many sections: %s", image_name);
return PLTHOOK_INTERNAL_ERROR;
}
data.sections[data.num_sections++] = sec;
sec++;
}
}
#endif
break;
case LC_DYLD_INFO_ONLY: /* (0x22|LC_REQ_DYLD) */
dyld_info= (struct dyld_info_command *)cmd;
DEBUG_CMD("LC_DYLD_INFO_ONLY\n"
" offset size\n"
" rebase %8x %8x\n"
" bind %8x %8x\n"
" weak_bind %8x %8x\n"
" lazy_bind %8x %8x\n"
" export_bind %8x %8x\n",
dyld_info->rebase_off, dyld_info->rebase_size,
dyld_info->bind_off, dyld_info->bind_size,
dyld_info->weak_bind_off, dyld_info->weak_bind_size,
dyld_info->lazy_bind_off, dyld_info->lazy_bind_size,
dyld_info->export_off, dyld_info->export_size);
break;
case LC_SYMTAB: /* 0x2 */
DEBUG_CMD("LC_SYMTAB\n");
break;
case LC_DYSYMTAB: /* 0xb */
DEBUG_CMD("LC_DYSYMTAB\n");
break;
case LC_LOAD_DYLIB: /* 0xc */
DEBUG_CMD("LC_LOAD_DYLIB\n");
break;
case LC_ID_DYLIB: /* 0xd */
DEBUG_CMD("LC_ID_DYLIB\n");
break;
case LC_LOAD_DYLINKER: /* 0xe */
DEBUG_CMD("LC_LOAD_DYLINKER\n");
break;
case LC_ROUTINES_64: /* 0x1a */
DEBUG_CMD("LC_ROUTINES_64\n");
break;
case LC_UUID: /* 0x1b */
DEBUG_CMD("LC_UUID\n");
break;
case LC_RPATH: /* (0x1c|LC_REQ_DYLD) */
DEBUG_CMD("LC_RPATH\n");
break;
case LC_CODE_SIGNATURE: /* 0x1d */
DEBUG_CMD("LC_CODE_SIGNATURE\n");
break;
case LC_VERSION_MIN_MACOSX: /* 0x24 */
DEBUG_CMD("LC_VERSION_MIN_MACOSX\n");
break;
case LC_FUNCTION_STARTS: /* 0x26 */
DEBUG_CMD("LC_FUNCTION_STARTS\n");
break;
case LC_MAIN: /* 0x28|LC_REQ_DYLD */
DEBUG_CMD("LC_MAIN\n");
break;
case LC_DATA_IN_CODE: /* 0x29 */
DEBUG_CMD("LC_DATA_IN_CODE\n");
break;
case LC_SOURCE_VERSION: /* 0x2A */
DEBUG_CMD("LC_SOURCE_VERSION\n");
break;
case LC_DYLIB_CODE_SIGN_DRS: /* 0x2B */
DEBUG_CMD("LC_DYLIB_CODE_SIGN_DRS\n");
break;
case LC_BUILD_VERSION: /* 0x32 */
DEBUG_CMD("LC_BUILD_VERSION\n");
break;
case LC_DYLD_EXPORTS_TRIE: /* (0x33|LC_REQ_DYLD) */
DEBUG_CMD("LC_DYLD_EXPORTS_TRIE\n");
break;
case LC_DYLD_CHAINED_FIXUPS: /* (0x34|LC_REQ_DYLD) */
data.chained_fixups = (struct linkedit_data_command *)cmd;
DEBUG_CMD("LC_DYLD_CHAINED_FIXUPS\n"
" cmdsize %u\n"
" dataoff %u (0x%x)\n"
" datasize %u\n",
data.chained_fixups->cmdsize,
data.chained_fixups->dataoff,
data.chained_fixups->dataoff,
data.chained_fixups->datasize);
break;
default:
DEBUG_CMD("LC_? (0x%x)\n", cmd->cmd);
}
cmd = (struct load_command *)((size_t)cmd + cmd->cmdsize);
}
DEBUG_CMD("CMD END\n");
if (data.linkedit_segment_idx == -1) {
set_errmsg("Cannot find the linkedit segment: %s", image_name);
return PLTHOOK_INVALID_FILE_FORMAT;
}
if (data.chained_fixups != NULL) {
int rv = read_chained_fixups(&data, image_name);
if (rv != 0) {
return rv;
}
} else {
nbind = 0;
nbind = set_bind_addrs(&data, nbind, dyld_info->bind_off, dyld_info->bind_size, 0);
nbind = set_bind_addrs(&data, nbind, dyld_info->weak_bind_off, dyld_info->weak_bind_size, 1);
nbind = set_bind_addrs(&data, nbind, dyld_info->lazy_bind_off, dyld_info->lazy_bind_size, 0);
size = offsetof(plthook_t, entries) + sizeof(bind_address_t) * nbind;
data.plthook = (plthook_t*)calloc(1, size);
if (data.plthook == NULL) {
set_errmsg("failed to allocate memory: %" PRIuPTR " bytes", size);
return PLTHOOK_OUT_OF_MEMORY;
}
data.plthook->num_entries = nbind;
nbind = 0;
nbind = set_bind_addrs(&data, nbind, dyld_info->bind_off, dyld_info->bind_size, 0);
nbind = set_bind_addrs(&data, nbind, dyld_info->weak_bind_off, dyld_info->weak_bind_size, 1);
nbind = set_bind_addrs(&data, nbind, dyld_info->lazy_bind_off, dyld_info->lazy_bind_size, 0);
}
set_mem_prot(data.plthook);
*plthook_out = data.plthook;
return 0;
}
static unsigned int set_bind_addrs(data_t *data, unsigned int idx, uint32_t bind_off, uint32_t bind_size, char weak)
{
const uint8_t *ptr = fileoff_to_vmaddr_in_segment(data, data->linkedit_segment_idx, bind_off);
const uint8_t *end = ptr + bind_size;
const char *sym_name;
int seg_index = 0;
uint64_t seg_offset = 0;
int addend = 0;
int count, skip;
#ifdef PLTHOOK_DEBUG_BIND
int cond = data->plthook != NULL;
#endif
while (ptr < end) {
uint8_t op = *ptr & BIND_OPCODE_MASK;
uint8_t imm = *ptr & BIND_IMMEDIATE_MASK;
int i;
DEBUG_BIND_IF(cond, "0x%02x: ", *ptr);
ptr++;
switch (op) {
case BIND_OPCODE_DONE:
DEBUG_BIND_IF(cond, "BIND_OPCODE_DONE\n");
break;
case BIND_OPCODE_SET_DYLIB_ORDINAL_IMM:
DEBUG_BIND_IF(cond, "BIND_OPCODE_SET_DYLIB_ORDINAL_IMM: ordinal = %u\n", imm);
break;
case BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB:
#ifdef PLTHOOK_DEBUG_BIND
DEBUG_BIND_IF(cond, "BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB: ordinal = %llu\n", uleb128(&ptr));
#else
uleb128(&ptr);
#endif
break;
case BIND_OPCODE_SET_DYLIB_SPECIAL_IMM:
if (imm == 0) {
DEBUG_BIND_IF(cond, "BIND_OPCODE_SET_DYLIB_SPECIAL_IMM: ordinal = 0\n");
} else {
DEBUG_BIND_IF(cond, "BIND_OPCODE_SET_DYLIB_SPECIAL_IMM: ordinal = %u\n", BIND_OPCODE_MASK | imm);
}
break;
case BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM:
sym_name = (const char*)ptr;
ptr += strlen(sym_name) + 1;
DEBUG_BIND_IF(cond, "BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM: sym_name = %s\n", sym_name);
break;
case BIND_OPCODE_SET_TYPE_IMM:
DEBUG_BIND_IF(cond, "BIND_OPCODE_SET_TYPE_IMM: type = %u\n", imm);
break;
case BIND_OPCODE_SET_ADDEND_SLEB:
addend = sleb128(&ptr);
DEBUG_BIND_IF(cond, "BIND_OPCODE_SET_ADDEND_SLEB: ordinal = %lld\n", addend);
break;
case BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB:
seg_index = imm;
seg_offset = uleb128(&ptr);
DEBUG_BIND_IF(cond, "BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB: seg_index = %u, seg_offset = 0x%llx\n", seg_index, seg_offset);
break;
case BIND_OPCODE_ADD_ADDR_ULEB:
seg_offset += uleb128(&ptr);
DEBUG_BIND_IF(cond, "BIND_OPCODE_ADD_ADDR_ULEB: seg_offset = 0x%llx\n", seg_offset);
break;
case BIND_OPCODE_DO_BIND:
set_bind_addr(data, &idx, sym_name, seg_index, seg_offset, addend, weak);
seg_offset += sizeof(void*);
DEBUG_BIND_IF(cond, "BIND_OPCODE_DO_BIND\n");
break;
case BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB:
set_bind_addr(data, &idx, sym_name, seg_index, seg_offset, addend, weak);
seg_offset += uleb128(&ptr) + sizeof(void*);
DEBUG_BIND_IF(cond, "BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB: seg_offset = 0x%llx\n", seg_offset);
break;
case BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED:
set_bind_addr(data, &idx, sym_name, seg_index, seg_offset, addend, weak);
seg_offset += imm * sizeof(void *) + sizeof(void*);
DEBUG_BIND_IF(cond, "BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED\n");
break;
case BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB:
count = uleb128(&ptr);
skip = uleb128(&ptr);
for (i = 0; i < count; i++) {
set_bind_addr(data, &idx, sym_name, seg_index, seg_offset, addend, weak);
seg_offset += skip + sizeof(void*);
}
DEBUG_BIND_IF(cond, "BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB\n");
break;
default:
DEBUG_BIND_IF(cond, "op: 0x%x, imm: 0x%x\n", op, imm);
}
}
return idx;
}
static void set_bind_addr(data_t *data, unsigned int *idx, const char *sym_name, int seg_index, int seg_offset, int addend, char weak)
{
if (data->plthook != NULL) {
size_t vmaddr = data->segments[seg_index]->vmaddr;
bind_address_t *bind_addr = &data->plthook->entries[*idx];
bind_addr->name = sym_name;
bind_addr->addend = addend;
bind_addr->weak = weak;
bind_addr->addr = (void**)(vmaddr + data->slide + seg_offset);
DEBUG_BIND("bind_address[%u]: %s, %d, %d, %p, %p, %p\n", *idx, sym_name, seg_index, seg_offset, (void*)vmaddr, (void*)data->slide, bind_addr->addr);
}
(*idx)++;
}
typedef struct {
const char *image_name;
FILE *fp;
const struct dyld_chained_starts_in_image *starts;
uint32_t seg_index; // i
uint16_t page_index; // j
off_t offset;
} chained_fixups_iter_t;
typedef struct {
uint16_t ptr_format;
union {
uint64_t raw;
struct dyld_chained_ptr_64_rebase rebase;
struct dyld_chained_ptr_64_bind bind;
struct dyld_chained_ptr_arm64e_rebase arm64e_rebase;
struct dyld_chained_ptr_arm64e_bind arm64e_bind;
struct dyld_chained_ptr_arm64e_bind24 arm64e_bind24;
struct dyld_chained_ptr_arm64e_auth_rebase arm64e_auth_rebase;
struct dyld_chained_ptr_arm64e_auth_bind arm64e_auth_bind;
struct dyld_chained_ptr_arm64e_auth_bind24 arm64e_auth_bind24;
} ptr;
off_t offset;
} chianed_fixups_entry_t;
static int chained_fixups_iter_init(chained_fixups_iter_t *iter, const char *image_name, const struct dyld_chained_starts_in_image *starts_offset);
static void chained_fixups_iter_deinit(chained_fixups_iter_t *iter);
static int chained_fixups_iter_rewind(chained_fixups_iter_t *iter);
static int chained_fixups_iter_next(chained_fixups_iter_t *iter, chianed_fixups_entry_t *entry);
static int chained_fixups_iter_init(chained_fixups_iter_t *iter, const char *image_name, const struct dyld_chained_starts_in_image *starts)
{
memset(iter, 0, sizeof(*iter));
iter->fp = fopen(image_name, "r");
if (iter->fp == NULL) {
set_errmsg("failed to open file %s (error: %s)", image_name, strerror(errno));
return PLTHOOK_FILE_NOT_FOUND;
}
iter->image_name = image_name;
iter->starts = starts;
return 0;
}
static void chained_fixups_iter_deinit(chained_fixups_iter_t *iter)
{
if (iter->fp != NULL) {
fclose(iter->fp);
iter->fp = NULL;
}
}
static int chained_fixups_iter_rewind(chained_fixups_iter_t *iter)
{
iter->seg_index = 0;
iter->page_index = 0;
iter->offset = 0;
return 0;
}
static int chained_fixups_iter_next(chained_fixups_iter_t *iter, chianed_fixups_entry_t *entry)
{
const struct dyld_chained_starts_in_image *starts = iter->starts;
uint32_t i = iter->seg_index;
uint16_t j = iter->page_index;
off_t offset = iter->offset;
next_segment:
if (i == starts->seg_count) {
return -1;
}
if (j == 0 && offset == 0) {
DEBUG_FIXUPS(" seg_info_offset[%u] %u\n",
i, starts->seg_info_offset[i]);
}
if (starts->seg_info_offset[i] == 0) {
i++;
j = 0;
offset = 0;
goto next_segment;
}
const struct dyld_chained_starts_in_segment* seg = (const struct dyld_chained_starts_in_segment*)((char*)starts + starts->seg_info_offset[i]);
if (j == 0 && offset == 0) {
DEBUG_FIXUPS(" dyld_chained_starts_in_segment\n"
" size %u\n"
" page_size 0x%x\n"
" pointer_format %u\n"
" segment_offset %llu (0x%llx)\n"
" max_valid_pointer %u\n"
" page_count %u\n",
seg->size, seg->page_size, seg->pointer_format, seg->segment_offset, seg->segment_offset, seg->max_valid_pointer, seg->page_count);
}
next_page:
if (j == seg->page_count) {
i++;
j = 0;
offset = 0;
goto next_segment;
}
if (seg->page_start[j] == DYLD_CHAINED_PTR_START_NONE) {
DEBUG_FIXUPS(" page_start[%u] DYLD_CHAINED_PTR_START_NONE\n", j);
j++;
offset = 0;
goto next_page;
}
if (offset == 0) {
DEBUG_FIXUPS(" page_start[%u] %u\n", j, seg->page_start[j]);
}
if (offset == 0) {
offset = seg->segment_offset + j * seg->page_size + seg->page_start[j];
}
if (fseeko(iter->fp, offset, SEEK_SET) != 0) {
set_errmsg("failed to seek to %lld in %s", offset, iter->image_name);
return PLTHOOK_INVALID_FILE_FORMAT;
}
entry->ptr_format = seg->pointer_format;
if (fread(&entry->ptr, sizeof(entry->ptr), 1, iter->fp) != 1) {
set_errmsg("failed to read fixup chain from %s", iter->image_name);
return PLTHOOK_INVALID_FILE_FORMAT;
}
entry->offset = offset;
switch (seg->pointer_format) {
case DYLD_CHAINED_PTR_64_OFFSET:
if (entry->ptr.bind.next) {
offset += entry->ptr.bind.next * 4;
} else {
j++;
offset = 0;
}
break;
default:
set_errmsg("unsupported pointer format %u in %s", seg->pointer_format, iter->image_name);
return PLTHOOK_INTERNAL_ERROR;
}
iter->seg_index = i;
iter->page_index = j;
iter->offset = offset;
return 0;
}
static int read_chained_fixups(data_t *d, const char *image_name)
{
const uint8_t *ptr = fileoff_to_vmaddr_in_segment(d, d->linkedit_segment_idx, d->chained_fixups->dataoff);
const struct dyld_chained_fixups_header *header = (const struct dyld_chained_fixups_header *)ptr;
const char *symbol_pool = (const char*)ptr + header->symbols_offset;
int rv;
unsigned int num_binds;
size_t size;
const struct dyld_chained_starts_in_image *starts = (const struct dyld_chained_starts_in_image *)(ptr + header->starts_offset);
const struct dyld_chained_import *import = (const struct dyld_chained_import *)(ptr + header->imports_offset);
chained_fixups_iter_t iter;
chianed_fixups_entry_t entry;
memset(&iter, 0, sizeof(chained_fixups_iter_t));
rv = chained_fixups_iter_init(&iter, image_name, starts);
if (rv != 0) {
return rv;
}
DEBUG_FIXUPS("dyld_chained_fixups_header\n"
" fixups_version %u\n"
" starts_offset %u\n"
" imports_offset %u\n"
" symbols_offset %u\n"
" imports_count %u\n"
" imports_format %u\n"
" symbols_format %u\n",
header->fixups_version,
header->starts_offset,
header->imports_offset,
header->symbols_offset,
header->imports_count,
header->imports_format,
header->symbols_format);
if (header->fixups_version != 0) {
set_errmsg("unknown chained fixups version %u", header->fixups_version);
rv = PLTHOOK_INVALID_FILE_FORMAT;
goto cleanup;
}
DEBUG_FIXUPS("dyld_chained_starts_in_image\n"
" seg_count %u\n",
starts->seg_count);
num_binds = 0;
while ((rv = chained_fixups_iter_next(&iter, &entry)) == 0) {
if (entry.ptr_format == DYLD_CHAINED_PTR_64_OFFSET && entry.ptr.bind.bind) {
num_binds++;
}
#if 0
if (entry.ptr.rebase.bind) {
DEBUG_FIXUPS(" 0x%08lX: raw: 0x%016lX bind: (next: %03u, ordinal: %06X, addend: %d)\n",
entry.offset, entry.ptr.raw, entry.ptr.bind.next, entry.ptr.bind.ordinal, entry.ptr.bind.addend);
} else {
DEBUG_FIXUPS(" 0x%08lX: raw: 0x%016lX rebase: (next: %03u, target: 0x%011lX, high8: 0x%02X)\n",
entry.offset, entry.ptr.raw, entry.ptr.rebase.next, entry.ptr.rebase.target, entry.ptr.rebase.high8);
}
#endif
}
if (rv > 0) {
goto cleanup;
}
size = offsetof(plthook_t, entries) + sizeof(bind_address_t) * num_binds;
d->plthook = (plthook_t*)calloc(1, size);
if (d->plthook == NULL) {
set_errmsg("failed to allocate memory: %" PRIuPTR " bytes", size);
rv = PLTHOOK_OUT_OF_MEMORY;
goto cleanup;
}
d->plthook->num_entries = num_binds;
chained_fixups_iter_rewind(&iter);
num_binds = 0;
while ((rv = chained_fixups_iter_next(&iter, &entry)) == 0) {
if (entry.ptr_format == DYLD_CHAINED_PTR_64_OFFSET && entry.ptr.bind.bind) {
uint16_t ordinal = entry.ptr.bind.ordinal;
uint32_t name_offset;
char weak = 0;
bind_address_t *bind_addr = &d->plthook->entries[num_binds];
#ifdef PLTHOOK_DEBUG_FIXUPS
int32_t lib_ordinal;
const char *libname;
#endif
switch (header->imports_format) {
case DYLD_CHAINED_IMPORT:
name_offset = import[ordinal].name_offset;
weak = import[ordinal].weak_import;
#ifdef PLTHOOK_DEBUG_FIXUPS
if (import[ordinal].lib_ordinal >= (uint8_t)BIND_SPECIAL_DYLIB_WEAK_LOOKUP) {
lib_ordinal = (int8_t)import[ordinal].lib_ordinal;
} else {
lib_ordinal = (uint8_t)import[ordinal].lib_ordinal;
}
#endif
break;
default:
DEBUG_FIXUPS("imports_format: %u\n", header->imports_format);
set_errmsg("unsupported imports format %u", header->imports_format);
rv = PLTHOOK_INTERNAL_ERROR;
goto cleanup;
}
bind_addr->name = symbol_pool + name_offset;
bind_addr->addr = (void**)fileoff_to_vmaddr(d, entry.offset);
bind_addr->addend = entry.ptr.bind.addend;
bind_addr->weak = weak;
#ifdef PLTHOOK_DEBUG_FIXUPS
switch (lib_ordinal) {
case BIND_SPECIAL_DYLIB_SELF:
libname = "this-image";
break;
case BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE:
libname = "main-executable";
break;
case BIND_SPECIAL_DYLIB_FLAT_LOOKUP:
libname = "flat-namespace";
break;
case BIND_SPECIAL_DYLIB_WEAK_LOOKUP:
libname = "weak";
break;
default:
libname = "?";
}
#endif
DEBUG_FIXUPS(" %-12s %-16s 0x%08llX bind %s/%s",
segment_name_from_addr(d, entry.offset), section_name_from_addr(d, entry.offset), entry.offset, libname, symbol_pool + name_offset);
if (entry.ptr.bind.addend != 0) {
DEBUG_FIXUPS(" + 0x%X", entry.ptr.bind.addend);
}
if (weak) {
DEBUG_FIXUPS(" [weak-import]");
}
DEBUG_FIXUPS("\n");
num_binds++;
} else if (entry.ptr_format == DYLD_CHAINED_PTR_64_OFFSET && !entry.ptr.bind.bind) {
DEBUG_FIXUPS(" %-12s %-16s 0x%08llX rebase 0x%08llX\n",
segment_name_from_addr(d, entry.offset), section_name_from_addr(d, entry.offset), entry.offset, entry.ptr.rebase.target);
}
}
chained_fixups_iter_deinit(&iter);
rv = 0;
cleanup:
chained_fixups_iter_deinit(&iter);
if (rv != 0 && d->plthook) {
free(d->plthook);
d->plthook = NULL;
}
return rv;
}
#ifdef PLTHOOK_DEBUG_FIXUPS
static const char *segment_name_from_addr(data_t *d, size_t addr)
{
int i;
for (i = 0; i < d->num_segments; i++) {
const struct segment_command_64 *seg = d->segments[i];
if (seg->fileoff <= addr && addr < seg->fileoff + seg->filesize) {
return seg->segname;
}
}
return "?";
}
static const char *section_name_from_addr(data_t *d, size_t addr)
{
int i;
for (i = 0; i < d->num_sections; i++) {
const struct section_64 *sec = d->sections[i];
if (sec->offset <= addr && addr < sec->offset + sec->size) {
return sec->sectname;
}
}
return "?";
}
#endif
static int set_mem_prot(plthook_t *plthook)
{
unsigned int pos = 0;
const char *name;
void **addr;
size_t start = (size_t)-1;
size_t end = 0;
mach_port_t task = mach_task_self();
vm_address_t vm_addr = 0;
vm_size_t vm_size;
vm_region_basic_info_data_64_t info;
mach_msg_type_number_t info_count = VM_REGION_BASIC_INFO_COUNT_64;
memory_object_name_t object = 0;