77 lines
3.1 KiB
Objective-C
77 lines
3.1 KiB
Objective-C
//
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// JITSupport.m
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// RetroArchiOS
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//
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// Created by Yoshi Sugawara on 9/25/21.
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// Copyright © 2021 RetroArch. All rights reserved.
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//
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// Copied from UTMApp, original author: osy
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//
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#import <Foundation/Foundation.h>
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#include <dlfcn.h>
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#include <mach/mach.h>
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#include <mach-o/loader.h>
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#include <mach-o/getsect.h>
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#include <pthread.h>
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extern int csops(pid_t pid, unsigned int ops, void * useraddr, size_t usersize);
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extern boolean_t exc_server(mach_msg_header_t *, mach_msg_header_t *);
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extern int ptrace(int request, pid_t pid, caddr_t addr, int data);
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#define CS_OPS_STATUS 0 /* return status */
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#define CS_KILL 0x00000200 /* kill process if it becomes invalid */
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#define CS_DEBUGGED 0x10000000 /* process is currently or has previously been debugged and allowed to run with invalid pages */
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#define PT_TRACE_ME 0 /* child declares it's being traced */
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#define PT_SIGEXC 12 /* signals as exceptions for current_proc */
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static void *exception_handler(void *argument) {
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mach_port_t port = *(mach_port_t *)argument;
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mach_msg_server(exc_server, 2048, port, 0);
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return NULL;
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}
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static bool jb_has_debugger_attached(void) {
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int flags;
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return !csops(getpid(), CS_OPS_STATUS, &flags, sizeof(flags)) && flags & CS_DEBUGGED;
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}
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bool jb_enable_ptrace_hack(void) {
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bool debugged = jb_has_debugger_attached();
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// Thanks to this comment: https://news.ycombinator.com/item?id=18431524
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// We use this hack to allow mmap with PROT_EXEC (which usually requires the
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// dynamic-codesigning entitlement) by tricking the process into thinking
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// that Xcode is debugging it. We abuse the fact that JIT is needed to
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// debug the process.
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if (ptrace(PT_TRACE_ME, 0, NULL, 0) < 0) {
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return false;
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}
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// ptracing ourselves confuses the kernel and will cause bad things to
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// happen to the system (hangs…) if an exception or signal occurs. Setup
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// some "safety nets" so we can cause the process to exit in a somewhat sane
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// state. We only need to do this if the debugger isn't attached. (It'll do
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// this itself, and if we do it we'll interfere with its normal operation
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// anyways.)
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if (!debugged) {
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// First, ensure that signals are delivered as Mach software exceptions…
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ptrace(PT_SIGEXC, 0, NULL, 0);
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// …then ensure that this exception goes through our exception handler.
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// I think it's OK to just watch for EXC_SOFTWARE because the other
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// exceptions (e.g. EXC_BAD_ACCESS, EXC_BAD_INSTRUCTION, and friends)
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// will end up being delivered as signals anyways, and we can get them
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// once they're resent as a software exception.
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mach_port_t port = MACH_PORT_NULL;
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mach_port_allocate(mach_task_self(), MACH_PORT_RIGHT_RECEIVE, &port);
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mach_port_insert_right(mach_task_self(), port, port, MACH_MSG_TYPE_MAKE_SEND);
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task_set_exception_ports(mach_task_self(), EXC_MASK_SOFTWARE, port, EXCEPTION_DEFAULT, THREAD_STATE_NONE);
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pthread_t thread;
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pthread_create(&thread, NULL, exception_handler, (void *)&port);
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}
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return true;
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}
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