#include <stdio.h>

#include <stdlib.h>

#include <dlfcn.h>

#include <unistd.h>

#include <mach/mach.h>

#include <stdbool.h>

#include <pthread.h>

#define ENSURE_SUCCESS(c) \

if ((ret = c) != KERN_SUCCESS) { \

mach_error( # c , ret); \

return ret; \

}

int main(int argc, const char *argv[]) {

if (argc < 3)

return -1;

kern_return_t ret;

vm_address_t r_libname;

vm_address_t stack;

vm_address_t code;

thread_t thread;

x86_thread_state64_t state;

mach_port_t task;

const char *libname = argv[1];

unsigned long long stackContents[5], stack_size, i; // the stack contents has to be an odd number of ull's for some reason (some aligning issue) in dlopen

unsigned char codeContents[38];

bzero(codeContents, sizeof(codeContents));

bzero(stackContents, sizeof(stackContents));

codeContents[0] = 0x55; // push rbp

codeContents[1] = 0x48;

codeContents[2] = 0x89;

codeContents[3] = 0xe5; // mov %rsp, %rbp

codeContents[4] = 0x48;

codeContents[5] = 0xbf; // mov r_libname, %rdi

stackContents[1] = (unsigned long long)dlopen;

stackContents[2] = (unsigned long long)mach_thread_self;

stackContents[4] = (unsigned long long)thread_suspend;

stack_size = 65536;

if (strcmp(argv[2], "self") == 0)

task = mach_task_self();

else

ENSURE_SUCCESS(task_for_pid(mach_task_self(), atoi(argv[2]), &task));

ENSURE_SUCCESS(vm_allocate(task, &r_libname, strlen(libname) + 1, true));

ENSURE_SUCCESS(vm_allocate(task, &stack, stack_size, true));

ENSURE_SUCCESS(vm_allocate(task, &code, sizeof(codeContents), true));

stackContents[0] = code;

stackContents[3] = (unsigned long long)code + 27;

ENSURE_SUCCESS(vm_write(task, r_libname, (vm_offset_t)libname, strlen(libname) + 1));

ENSURE_SUCCESS(vm_write(task, stack + stack_size-sizeof(stackContents), (vm_offset_t)stackContents, sizeof(stackContents)));

memcpy(&codeContents[6], &r_libname, sizeof(unsigned long long));

codeContents[14] = 0x48;

codeContents[15] = 0xbe;

codeContents[16] = 0x2; // mov 0x2, %rsi

codeContents[24] = 0x5d; // pop %rbp

codeContents[25] = 0x90; // nop / int 3 depending if im debugging

codeContents[26] = 0xc3; // ret

codeContents[27] = 0x48;

codeContents[28] = 0x89;

codeContents[29] = 0xc7;

codeContents[30] = 0xc3;

ENSURE_SUCCESS(vm_write(task, code, (vm_offset_t)codeContents, sizeof(codeContents)));

ENSURE_SUCCESS(vm_protect(task, code, sizeof(codeContents), false, VM_PROT_EXECUTE | VM_PROT_READ));

printf("Created code region at %p:\n", (void *)code);

for (i = 0; i < sizeof(codeContents); i++) {

printf("0x%02x ", codeContents[i]);

}

puts("");

printf("Created stack at %p with top of stack at %p\n", (void*)stack, (void*)(stack + stack_size));

for (i = 0; i < sizeof(stackContents) / sizeof(stackContents[0]); i++) {

printf("0x%02llx:\t0x%02llx\n", (stack + stack_size - sizeof(stackContents) + (i * sizeof(unsigned long long))), stackContents[i]);

}

bzero(&state, sizeof(state));

state.__rip = (uint64_t)dlsym(RTLD_DEFAULT, "_pthread_set_self");

state.__rdi = stack;

state.__rsp = stack + stack_size-sizeof(stackContents); // end of stack minus returns

state.__rbp = state.__rsp;

printf("Found _pthread_set_self at %p\n", (void *)state.__rip);

ENSURE_SUCCESS(thread_create_running(task, x86_THREAD_STATE64, (thread_state_t)(&state), x86_THREAD_STATE64_COUNT, &thread));

if (strcmp(argv[2], "self") == 0) {

int rv = pthread_join(*(pthread_t *)stack, NULL);

if (rv) {

fprintf(stderr, "pthread_join: (%d) %s\n", rv, strerror(rv));

sleep(1); // let the dylib actually load in the other thread, it wouldn't appear that there exists mach thread waiting, and I'm too lazy to create a semaphore and using the value of `stack` for a pthread_t in pthread_join doesn't work

}

}

}