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Fix iOS 14.5 crash #83

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Fix iOS 14.5 crash #83

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c7810b6
fix the code indentation
shino-996 Feb 5, 2021
e1f8e9b
add write protection when writing data section
shino-996 Feb 5, 2021
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63 changes: 31 additions & 32 deletions fishhook.c
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,10 @@ typedef struct nlist nlist_t;
#define SEG_DATA_CONST "__DATA_CONST"
#endif

#ifndef SEG_AUTH_CONST
#define SEG_AUTH_CONST "__AUTH_CONST"
#endif

struct rebindings_entry {
struct rebinding *rebindings;
size_t rebindings_nel;
Expand Down Expand Up @@ -89,8 +93,7 @@ static vm_prot_t get_protection(void *sectionStart) {
#if __LP64__
mach_msg_type_number_t count = VM_REGION_BASIC_INFO_COUNT_64;
vm_region_basic_info_data_64_t info;
kern_return_t info_ret = vm_region_64(
task, &address, &size, VM_REGION_BASIC_INFO_64, (vm_region_info_64_t)&info, &count, &object);
kern_return_t info_ret = vm_region_64(task, &address, &size, VM_REGION_BASIC_INFO_64, (vm_region_info_64_t)&info, &count, &object);
#else
mach_msg_type_number_t count = VM_REGION_BASIC_INFO_COUNT;
vm_region_basic_info_data_t info;
Expand All @@ -102,24 +105,19 @@ static vm_prot_t get_protection(void *sectionStart) {
return VM_PROT_READ;
}
}

static void perform_rebinding_with_section(struct rebindings_entry *rebindings,
section_t *section,
intptr_t slide,
nlist_t *symtab,
char *strtab,
uint32_t *indirect_symtab) {
const bool isDataConst = strcmp(section->segname, SEG_DATA_CONST) == 0;
uint32_t *indirect_symbol_indices = indirect_symtab + section->reserved1;
void **indirect_symbol_bindings = (void **)((uintptr_t)slide + section->addr);
vm_prot_t oldProtection = VM_PROT_READ;
if (isDataConst) {
oldProtection = get_protection(rebindings);
mprotect(indirect_symbol_bindings, section->size, PROT_READ | PROT_WRITE);
}
for (uint i = 0; i < section->size / sizeof(void *); i++) {
uint32_t symtab_index = indirect_symbol_indices[i];
if (symtab_index == INDIRECT_SYMBOL_ABS || symtab_index == INDIRECT_SYMBOL_LOCAL ||
symtab_index == (INDIRECT_SYMBOL_LOCAL | INDIRECT_SYMBOL_ABS)) {
symtab_index == (INDIRECT_SYMBOL_LOCAL | INDIRECT_SYMBOL_ABS)) {
continue;
}
uint32_t strtab_offset = symtab[symtab_index].n_un.n_strx;
Expand All @@ -134,27 +132,27 @@ static void perform_rebinding_with_section(struct rebindings_entry *rebindings,
indirect_symbol_bindings[i] != cur->rebindings[j].replacement) {
*(cur->rebindings[j].replaced) = indirect_symbol_bindings[i];
}
bool is_prot_changed = false;
void **address_to_write = indirect_symbol_bindings + i;
vm_prot_t prot = get_protection(address_to_write);
if ((prot & VM_PROT_WRITE) == 0) {
is_prot_changed = true;
kern_return_t success = vm_protect(mach_task_self(), (vm_address_t)address_to_write, sizeof(void *), false, prot | VM_PROT_WRITE);
if (success != KERN_SUCCESS) {
goto symbol_loop;
}
}
indirect_symbol_bindings[i] = cur->rebindings[j].replacement;
if (is_prot_changed) {
vm_protect(mach_task_self(), (vm_address_t)address_to_write, sizeof(void *), false, prot);
}
goto symbol_loop;
}
}
cur = cur->next;
}
symbol_loop:;
}
if (isDataConst) {
int protection = 0;
if (oldProtection & VM_PROT_READ) {
protection |= PROT_READ;
}
if (oldProtection & VM_PROT_WRITE) {
protection |= PROT_WRITE;
}
if (oldProtection & VM_PROT_EXECUTE) {
protection |= PROT_EXEC;
}
mprotect(indirect_symbol_bindings, section->size, protection);
}
}

static void rebind_symbols_for_image(struct rebindings_entry *rebindings,
Expand Down Expand Up @@ -202,7 +200,8 @@ static void rebind_symbols_for_image(struct rebindings_entry *rebindings,
cur_seg_cmd = (segment_command_t *)cur;
if (cur_seg_cmd->cmd == LC_SEGMENT_ARCH_DEPENDENT) {
if (strcmp(cur_seg_cmd->segname, SEG_DATA) != 0 &&
strcmp(cur_seg_cmd->segname, SEG_DATA_CONST) != 0) {
strcmp(cur_seg_cmd->segname, SEG_DATA_CONST) != 0 &&
strcmp(cur_seg_cmd->segname, SEG_AUTH_CONST) != 0) {
continue;
}
for (uint j = 0; j < cur_seg_cmd->nsects; j++) {
Expand All @@ -221,21 +220,21 @@ static void rebind_symbols_for_image(struct rebindings_entry *rebindings,

static void _rebind_symbols_for_image(const struct mach_header *header,
intptr_t slide) {
rebind_symbols_for_image(_rebindings_head, header, slide);
rebind_symbols_for_image(_rebindings_head, header, slide);
}

int rebind_symbols_image(void *header,
intptr_t slide,
struct rebinding rebindings[],
size_t rebindings_nel) {
struct rebindings_entry *rebindings_head = NULL;
int retval = prepend_rebindings(&rebindings_head, rebindings, rebindings_nel);
rebind_symbols_for_image(rebindings_head, (const struct mach_header *) header, slide);
if (rebindings_head) {
free(rebindings_head->rebindings);
}
free(rebindings_head);
return retval;
struct rebindings_entry *rebindings_head = NULL;
int retval = prepend_rebindings(&rebindings_head, rebindings, rebindings_nel);
rebind_symbols_for_image(rebindings_head, (const struct mach_header *) header, slide);
if (rebindings_head) {
free(rebindings_head->rebindings);
}
free(rebindings_head);
return retval;
}

int rebind_symbols(struct rebinding rebindings[], size_t rebindings_nel) {
Expand Down