mirror of
https://github.com/topjohnwu/Magisk.git
synced 2024-12-26 09:07:38 +00:00
572 lines
18 KiB
C++
572 lines
18 KiB
C++
#include <dlfcn.h>
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#include <sys/mount.h>
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#include <xhook.h>
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#include <bitset>
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#include <utils.hpp>
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#include <flags.h>
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#include <daemon.hpp>
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#include "zygisk.hpp"
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#include "memory.hpp"
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#include "module.hpp"
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#include "deny/deny.hpp"
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using namespace std;
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using jni_hook::hash_map;
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using jni_hook::tree_map;
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using xstring = jni_hook::string;
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// Extreme verbose logging
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//#define ZLOGV(...) ZLOGD(__VA_ARGS__)
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#define ZLOGV(...)
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namespace {
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enum {
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UNMOUNT_FLAG,
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FORK_AND_SPECIALIZE,
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APP_SPECIALIZE,
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SERVER_SPECIALIZE,
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FLAG_MAX
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};
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#define DCL_PRE_POST(name) \
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void name##_pre(); \
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void name##_post();
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struct HookContext {
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JNIEnv *env;
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union {
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AppSpecializeArgsImpl *args;
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ServerSpecializeArgsImpl *server_args;
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void *raw_args;
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};
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const char *process;
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int pid;
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bitset<FLAG_MAX> flags;
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AppInfo info;
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vector<ZygiskModule> modules;
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HookContext() : pid(-1), info{} {}
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static void close_fds();
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DCL_PRE_POST(fork)
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void run_modules_pre(const vector<int> &fds);
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void run_modules_post();
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DCL_PRE_POST(nativeForkAndSpecialize)
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DCL_PRE_POST(nativeSpecializeAppProcess)
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DCL_PRE_POST(nativeForkSystemServer)
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};
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#undef DCL_PRE_POST
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struct StringCmp {
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using is_transparent = void;
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bool operator()(string_view a, string_view b) const { return a < b; }
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};
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// Global variables
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vector<tuple<const char *, const char *, void **>> *xhook_list;
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map<string, vector<JNINativeMethod>, StringCmp> *jni_hook_list;
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hash_map<xstring, tree_map<xstring, tree_map<xstring, void *>>> *jni_method_map;
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// Current context
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HookContext *g_ctx;
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const JNINativeInterface *old_functions;
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JNINativeInterface *new_functions;
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#define HOOK_JNI(method) \
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if (methods[i].name == #method##sv) { \
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int j = 0; \
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for (; j < method##_methods_num; ++j) { \
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if (strcmp(methods[i].signature, method##_methods[j].signature) == 0) { \
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jni_hook_list->try_emplace(className).first->second.push_back(methods[i]); \
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method##_orig = methods[i].fnPtr; \
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newMethods[i] = method##_methods[j]; \
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ZLOGI("replaced %s#" #method "\n", className); \
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--hook_cnt; \
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break; \
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} \
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} \
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if (j == method##_methods_num) { \
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ZLOGE("unknown signature of %s#" #method ": %s\n", className, methods[i].signature); \
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} \
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continue; \
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}
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// JNI method hook definitions, auto generated
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#include "jni_hooks.hpp"
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#undef HOOK_JNI
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jclass gClassRef;
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jmethodID class_getName;
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string get_class_name(JNIEnv *env, jclass clazz) {
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if (!gClassRef) {
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jclass cls = env->FindClass("java/lang/Class");
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gClassRef = (jclass) env->NewGlobalRef(cls);
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env->DeleteLocalRef(cls);
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class_getName = env->GetMethodID(gClassRef, "getName", "()Ljava/lang/String;");
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}
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auto nameRef = (jstring) env->CallObjectMethod(clazz, class_getName);
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const char *name = env->GetStringUTFChars(nameRef, nullptr);
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string className(name);
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env->ReleaseStringUTFChars(nameRef, name);
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std::replace(className.begin(), className.end(), '.', '/');
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return className;
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}
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// -----------------------------------------------------------------
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#define DCL_HOOK_FUNC(ret, func, ...) \
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ret (*old_##func)(__VA_ARGS__); \
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ret new_##func(__VA_ARGS__)
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jint env_RegisterNatives(
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JNIEnv *env, jclass clazz, const JNINativeMethod *methods, jint numMethods) {
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auto className = get_class_name(env, clazz);
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ZLOGV("JNIEnv->RegisterNatives [%s]\n", className.data());
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auto newMethods = hookAndSaveJNIMethods(className.data(), methods, numMethods);
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return old_functions->RegisterNatives(env, clazz, newMethods.get() ?: methods, numMethods);
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}
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DCL_HOOK_FUNC(int, jniRegisterNativeMethods,
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JNIEnv *env, const char *className, const JNINativeMethod *methods, int numMethods) {
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ZLOGV("jniRegisterNativeMethods [%s]\n", className);
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auto newMethods = hookAndSaveJNIMethods(className, methods, numMethods);
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return old_jniRegisterNativeMethods(env, className, newMethods.get() ?: methods, numMethods);
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}
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// Skip actual fork and return cached result if applicable
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// Also unload first stage zygisk if necessary
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DCL_HOOK_FUNC(int, fork) {
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unload_first_stage();
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return (g_ctx && g_ctx->pid >= 0) ? g_ctx->pid : old_fork();
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}
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// Unmount stuffs in the process's private mount namespace
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DCL_HOOK_FUNC(int, unshare, int flags) {
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int res = old_unshare(flags);
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if (g_ctx && res == 0) {
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if (g_ctx->flags[UNMOUNT_FLAG]) {
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revert_unmount();
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} else {
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umount2("/system/bin/app_process64", MNT_DETACH);
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umount2("/system/bin/app_process32", MNT_DETACH);
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}
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}
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return res;
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}
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// A place to clean things up before calling into zygote::ForkCommon/SpecializeCommon
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DCL_HOOK_FUNC(void, android_log_close) {
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HookContext::close_fds();
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if (g_ctx && g_ctx->pid <= 0) {
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// In child process, no longer be able to access to magiskd
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android_logging();
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}
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old_android_log_close();
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}
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// -----------------------------------------------------------------
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// The original android::AppRuntime virtual table
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void **gAppRuntimeVTable;
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// This method is a trampoline for hooking JNIEnv->RegisterNatives
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void onVmCreated(void *self, JNIEnv* env) {
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ZLOGD("AppRuntime::onVmCreated\n");
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// Restore virtual table
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auto new_table = *reinterpret_cast<void***>(self);
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*reinterpret_cast<void***>(self) = gAppRuntimeVTable;
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delete[] new_table;
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new_functions = new JNINativeInterface();
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memcpy(new_functions, env->functions, sizeof(*new_functions));
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new_functions->RegisterNatives = &env_RegisterNatives;
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// Replace the function table in JNIEnv to hook RegisterNatives
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old_functions = env->functions;
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env->functions = new_functions;
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}
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template<int N>
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void vtable_entry(void *self, JNIEnv* env) {
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// The first invocation will be onVmCreated. It will also restore the vtable.
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onVmCreated(self, env);
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// Call original function
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reinterpret_cast<decltype(&onVmCreated)>(gAppRuntimeVTable[N])(self, env);
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}
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// This method is a trampoline for swizzling android::AppRuntime vtable
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bool swizzled = false;
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DCL_HOOK_FUNC(void, setArgv0, void *self, const char *argv0, bool setProcName) {
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if (swizzled) {
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old_setArgv0(self, argv0, setProcName);
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return;
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}
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ZLOGD("AndroidRuntime::setArgv0\n");
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// We don't know which entry is onVmCreated, so overwrite every one
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// We also don't know the size of the vtable, but 8 is more than enough
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auto new_table = new void*[8];
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new_table[0] = reinterpret_cast<void*>(&vtable_entry<0>);
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new_table[1] = reinterpret_cast<void*>(&vtable_entry<1>);
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new_table[2] = reinterpret_cast<void*>(&vtable_entry<2>);
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new_table[3] = reinterpret_cast<void*>(&vtable_entry<3>);
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new_table[4] = reinterpret_cast<void*>(&vtable_entry<4>);
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new_table[5] = reinterpret_cast<void*>(&vtable_entry<5>);
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new_table[6] = reinterpret_cast<void*>(&vtable_entry<6>);
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new_table[7] = reinterpret_cast<void*>(&vtable_entry<7>);
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// Swizzle C++ vtable to hook virtual function
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gAppRuntimeVTable = *reinterpret_cast<void***>(self);
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*reinterpret_cast<void***>(self) = new_table;
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swizzled = true;
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old_setArgv0(self, argv0, setProcName);
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}
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#undef DCL_HOOK_FUNC
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// -----------------------------------------------------------------
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void hookJniNativeMethods(JNIEnv *env, const char *clz, JNINativeMethod *methods, int numMethods) {
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auto class_map = jni_method_map->find(clz);
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if (class_map == jni_method_map->end()) {
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for (int i = 0; i < numMethods; ++i) {
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methods[i].fnPtr = nullptr;
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}
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return;
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}
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vector<JNINativeMethod> hooks;
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for (int i = 0; i < numMethods; ++i) {
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auto method_map = class_map->second.find(methods[i].name);
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if (method_map != class_map->second.end()) {
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auto it = method_map->second.find(methods[i].signature);
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if (it != method_map->second.end()) {
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// Copy the JNINativeMethod
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hooks.push_back(methods[i]);
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// Save the original function pointer
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methods[i].fnPtr = it->second;
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// Do not allow double hook, remove method from map
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method_map->second.erase(it);
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continue;
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}
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}
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// No matching method found, set fnPtr to null
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methods[i].fnPtr = nullptr;
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}
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if (hooks.empty())
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return;
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old_jniRegisterNativeMethods(env, clz, hooks.data(), hooks.size());
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}
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bool ZygiskModule::registerModule(ApiTable *table, long *module) {
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long ver = *module;
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// Unsupported version
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if (ver > ZYGISK_API_VERSION)
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return false;
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// Set the actual module_abi*
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table->module->ver = module;
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// Fill in API accordingly with module API version
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table->v1.hookJniNativeMethods = &hookJniNativeMethods;
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table->v1.pltHookRegister = [](const char *path, const char *symbol, void *n, void **o) {
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xhook_register(path, symbol, n, o);
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};
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table->v1.pltHookExclude = [](const char *path, const char *symbol) {
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xhook_ignore(path, symbol);
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};
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table->v1.pltHookCommit = []() { return xhook_refresh(0) == 0; };
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table->v1.connectCompanion = [](ZygiskModule *m) { return m->connectCompanion(); };
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table->v1.setOption = [](ZygiskModule *m, auto opt) { m->setOption(opt); };
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return true;
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}
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int ZygiskModule::connectCompanion() const {
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if (int fd = connect_daemon(); fd >= 0) {
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write_int(fd, ZYGISK_REQUEST);
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write_int(fd, ZYGISK_CONNECT_COMPANION);
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write_int(fd, id);
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return fd;
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}
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return -1;
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}
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void ZygiskModule::setOption(zygisk::Option opt) {
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if (g_ctx == nullptr)
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return;
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switch (opt) {
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case zygisk::FORCE_DENYLIST_UNMOUNT:
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g_ctx->flags[UNMOUNT_FLAG] = true;
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break;
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case zygisk::DLCLOSE_MODULE_LIBRARY:
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unload = true;
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break;
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}
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}
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void HookContext::run_modules_pre(const vector<int> &fds) {
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char buf[256];
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for (int i = 0; i < fds.size(); ++i) {
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snprintf(buf, sizeof(buf), "/proc/self/fd/%d", fds[i]);
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if (void *h = dlopen(buf, RTLD_LAZY)) {
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void (*module_entry)(void *, void *);
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*(void **) &module_entry = dlsym(h, "zygisk_module_entry");
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if (module_entry) {
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modules.emplace_back(i, h);
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auto api = new ApiTable(&modules.back());
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module_entry(api, env);
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}
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}
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close(fds[i]);
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}
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for (auto &m : modules) {
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if (flags[APP_SPECIALIZE]) {
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m.preAppSpecialize(args);
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} else if (flags[SERVER_SPECIALIZE]) {
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m.preServerSpecialize(server_args);
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}
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}
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}
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void HookContext::run_modules_post() {
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for (auto &m : modules) {
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if (flags[APP_SPECIALIZE]) {
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m.postAppSpecialize(args);
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} else if (flags[SERVER_SPECIALIZE]) {
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m.postServerSpecialize(server_args);
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}
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if (m.unload) {
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dlclose(m.handle);
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}
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}
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}
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void HookContext::close_fds() {
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close(logd_fd.exchange(-1));
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}
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// -----------------------------------------------------------------
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void HookContext::nativeSpecializeAppProcess_pre() {
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g_ctx = this;
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flags[APP_SPECIALIZE] = true;
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process = env->GetStringUTFChars(args->nice_name, nullptr);
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if (flags[FORK_AND_SPECIALIZE]) {
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ZLOGV("pre forkAndSpecialize [%s]\n", process);
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} else {
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ZLOGV("pre specialize [%s]\n", process);
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}
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auto module_fds = remote_get_info(args->uid, process, &info);
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if (info.on_denylist) {
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// TODO: Handle MOUNT_EXTERNAL_NONE on older platforms
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ZLOGI("[%s] is on the denylist\n", process);
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flags[UNMOUNT_FLAG] = true;
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} else {
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run_modules_pre(module_fds);
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}
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}
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void HookContext::nativeSpecializeAppProcess_post() {
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if (flags[FORK_AND_SPECIALIZE]) {
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ZLOGV("post forkAndSpecialize [%s]\n", process);
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} else {
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ZLOGV("post specialize [%s]\n", process);
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}
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env->ReleaseStringUTFChars(args->nice_name, process);
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if (info.on_denylist) {
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self_unload();
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} else {
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run_modules_post();
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if (info.is_magisk_app) {
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setenv("ZYGISK_ENABLED", "1", 1);
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} else if (args->is_child_zygote && *args->is_child_zygote) {
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// If we are in child zygote, unhook all zygisk hooks
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// Modules still have their code loaded and can do whatever they want
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unhook_functions();
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}
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}
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g_ctx = nullptr;
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}
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void HookContext::nativeForkSystemServer_pre() {
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fork_pre();
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flags[SERVER_SPECIALIZE] = true;
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if (pid == 0) {
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ZLOGV("pre forkSystemServer\n");
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run_modules_pre(remote_get_info(1000, "system_server", &info));
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close_fds();
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}
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}
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void HookContext::nativeForkSystemServer_post() {
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if (pid == 0) {
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android_logging();
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ZLOGV("post forkSystemServer\n");
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run_modules_post();
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}
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fork_post();
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}
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void HookContext::nativeForkAndSpecialize_pre() {
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fork_pre();
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flags[FORK_AND_SPECIALIZE] = true;
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if (pid == 0) {
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nativeSpecializeAppProcess_pre();
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close_fds();
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}
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}
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void HookContext::nativeForkAndSpecialize_post() {
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if (pid == 0) {
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android_logging();
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nativeSpecializeAppProcess_post();
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}
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fork_post();
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}
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int sigmask(int how, int signum) {
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sigset_t set;
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sigemptyset(&set);
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sigaddset(&set, signum);
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return sigprocmask(how, &set, nullptr);
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}
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// Do our own fork before loading any 3rd party code
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// First block SIGCHLD, unblock after original fork is done
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void HookContext::fork_pre() {
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g_ctx = this;
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sigmask(SIG_BLOCK, SIGCHLD);
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pid = old_fork();
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}
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// Unblock SIGCHLD in case the original method didn't
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void HookContext::fork_post() {
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sigmask(SIG_UNBLOCK, SIGCHLD);
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g_ctx = nullptr;
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}
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} // namespace
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static bool hook_refresh() {
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if (xhook_refresh(0) == 0) {
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xhook_clear();
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ZLOGI("xhook success\n");
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return true;
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} else {
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ZLOGE("xhook failed\n");
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return false;
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}
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}
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static int hook_register(const char *path, const char *symbol, void *new_func, void **old_func) {
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int ret = xhook_register(path, symbol, new_func, old_func);
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if (ret != 0) {
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ZLOGE("Failed to register hook \"%s\"\n", symbol);
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return ret;
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}
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xhook_list->emplace_back(path, symbol, old_func);
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return 0;
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}
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#define XHOOK_REGISTER_SYM(PATH_REGEX, SYM, NAME) \
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hook_register(PATH_REGEX, SYM, (void*) new_##NAME, (void **) &old_##NAME)
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#define XHOOK_REGISTER(PATH_REGEX, NAME) \
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XHOOK_REGISTER_SYM(PATH_REGEX, #NAME, NAME)
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#define ANDROID_RUNTIME ".*/libandroid_runtime.so$"
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#define APP_PROCESS "^/system/bin/app_process.*"
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void hook_functions() {
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#if MAGISK_DEBUG
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// xhook_enable_debug(1);
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xhook_enable_sigsegv_protection(0);
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#endif
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default_new(xhook_list);
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|
default_new(jni_hook_list);
|
|
default_new(jni_method_map);
|
|
|
|
XHOOK_REGISTER(ANDROID_RUNTIME, fork);
|
|
XHOOK_REGISTER(ANDROID_RUNTIME, unshare);
|
|
XHOOK_REGISTER(ANDROID_RUNTIME, jniRegisterNativeMethods);
|
|
XHOOK_REGISTER_SYM(ANDROID_RUNTIME, "__android_log_close", android_log_close);
|
|
hook_refresh();
|
|
|
|
// Remove unhooked methods
|
|
xhook_list->erase(
|
|
std::remove_if(xhook_list->begin(), xhook_list->end(),
|
|
[](auto &t) { return *std::get<2>(t) == nullptr;}),
|
|
xhook_list->end());
|
|
|
|
if (old_jniRegisterNativeMethods == nullptr) {
|
|
ZLOGD("jniRegisterNativeMethods not hooked, using fallback\n");
|
|
|
|
// android::AndroidRuntime::setArgv0(const char*, bool)
|
|
XHOOK_REGISTER_SYM(APP_PROCESS, "_ZN7android14AndroidRuntime8setArgv0EPKcb", setArgv0);
|
|
hook_refresh();
|
|
|
|
// We still need old_jniRegisterNativeMethods as other code uses it
|
|
// android::AndroidRuntime::registerNativeMethods(_JNIEnv*, const char*, const JNINativeMethod*, int)
|
|
constexpr char sig[] = "_ZN7android14AndroidRuntime21registerNativeMethodsEP7_JNIEnvPKcPK15JNINativeMethodi";
|
|
*(void **) &old_jniRegisterNativeMethods = dlsym(RTLD_DEFAULT, sig);
|
|
}
|
|
}
|
|
|
|
bool unhook_functions() {
|
|
bool success = true;
|
|
|
|
// Restore JNIEnv
|
|
if (g_ctx->env->functions == new_functions) {
|
|
g_ctx->env->functions = old_functions;
|
|
if (gClassRef) {
|
|
g_ctx->env->DeleteGlobalRef(gClassRef);
|
|
gClassRef = nullptr;
|
|
class_getName = nullptr;
|
|
}
|
|
}
|
|
|
|
// Do NOT call the destructor
|
|
operator delete(jni_method_map);
|
|
// Directly unmap the whole memory block
|
|
jni_hook::memory_block::release();
|
|
|
|
// Unhook JNI methods
|
|
for (const auto &[clz, methods] : *jni_hook_list) {
|
|
if (!methods.empty() && old_jniRegisterNativeMethods(
|
|
g_ctx->env, clz.data(), methods.data(), methods.size()) != 0) {
|
|
ZLOGE("Failed to restore JNI hook of class [%s]\n", clz.data());
|
|
success = false;
|
|
}
|
|
}
|
|
delete jni_hook_list;
|
|
|
|
// Unhook xhook
|
|
for (const auto &[path, sym, old_func] : *xhook_list) {
|
|
if (xhook_register(path, sym, *old_func, nullptr) != 0) {
|
|
ZLOGE("Failed to register xhook [%s]\n", sym);
|
|
success = false;
|
|
}
|
|
}
|
|
delete xhook_list;
|
|
if (!hook_refresh()) {
|
|
ZLOGE("Failed to restore xhook\n");
|
|
success = false;
|
|
}
|
|
|
|
return success;
|
|
}
|