mirror of
https://github.com/topjohnwu/Magisk.git
synced 2024-11-24 10:35:26 +00:00
436 lines
13 KiB
C++
436 lines
13 KiB
C++
#include <dlfcn.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 "inject.hpp"
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#include "memory.hpp"
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#include "api.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 VLOG(...) LOGD(__VA_ARGS__)
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//#define VLOG(...)
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namespace {
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enum {
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DENY_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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SpecializeAppProcessArgs *args;
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ForkSystemServerArgs *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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HookContext() : pid(-1) {}
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static void close_fds();
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DCL_PRE_POST(fork)
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DCL_PRE_POST(run_modules)
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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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for (int j = 0; 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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LOGI("zygisk: 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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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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VLOG("zygisk: 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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VLOG("zygisk: 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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DCL_HOOK_FUNC(int, fork) {
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return (g_ctx && g_ctx->pid >= 0) ? g_ctx->pid : old_fork();
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}
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// This is the latest point where we can still connect to the magiskd main socket
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DCL_HOOK_FUNC(int, selinux_android_setcontext,
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uid_t uid, int isSystemServer, const char *seinfo, const char *pkgname) {
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if (g_ctx && g_ctx->flags[DENY_FLAG]) {
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if (remote_request_unmount() == 0) {
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LOGD("zygisk: mount namespace cleaned up\n");
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}
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}
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return old_selinux_android_setcontext(uid, isSystemServer, seinfo, pkgname);
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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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LOGD("zygisk: 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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LOGD("zygisk: 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 HookContext::run_modules_pre() { /* TODO */ }
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void HookContext::run_modules_post() { /* TODO */ }
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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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VLOG("zygisk: pre forkAndSpecialize [%s]\n", process);
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} else {
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VLOG("zygisk: pre specialize [%s]\n", process);
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}
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/* TODO: Handle MOUNT_EXTERNAL_NONE */
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if (args->mount_external != 0 && remote_check_denylist(args->uid, process)) {
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flags[DENY_FLAG] = true;
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LOGI("zygisk: [%s] is on the denylist\n", process);
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} else {
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run_modules_pre();
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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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VLOG("zygisk: post forkAndSpecialize [%s]\n", process);
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} else {
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VLOG("zygisk: post specialize [%s]\n", process);
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}
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env->ReleaseStringUTFChars(args->nice_name, process);
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if (flags[DENY_FLAG]) {
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self_unload();
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} else {
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run_modules_post();
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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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VLOG("zygisk: pre forkSystemServer\n");
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run_modules_pre();
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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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VLOG("zygisk: 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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LOGI("zygisk: xhook success\n");
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return true;
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} else {
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LOGE("zygisk: 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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LOGE("hook: 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);
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default_new(jni_method_map);
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XHOOK_REGISTER(ANDROID_RUNTIME, fork);
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XHOOK_REGISTER(ANDROID_RUNTIME, selinux_android_setcontext);
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XHOOK_REGISTER(ANDROID_RUNTIME, jniRegisterNativeMethods);
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XHOOK_REGISTER_SYM(ANDROID_RUNTIME, "__android_log_close", android_log_close);
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hook_refresh();
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// Remove unhooked methods
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xhook_list->erase(
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std::remove_if(xhook_list->begin(), xhook_list->end(),
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[](auto &t) { return *std::get<2>(t) == nullptr;}),
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xhook_list->end());
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if (old_jniRegisterNativeMethods == nullptr) {
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LOGD("zygisk: jniRegisterNativeMethods not hooked, using fallback\n");
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// android::AndroidRuntime::setArgv0(const char*, bool)
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XHOOK_REGISTER_SYM(APP_PROCESS, "_ZN7android14AndroidRuntime8setArgv0EPKcb", setArgv0);
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hook_refresh();
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// We still need old_jniRegisterNativeMethods as other code uses it
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// android::AndroidRuntime::registerNativeMethods(_JNIEnv*, const char*, const JNINativeMethod*, int)
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constexpr char sig[] = "_ZN7android14AndroidRuntime21registerNativeMethodsEP7_JNIEnvPKcPK15JNINativeMethodi";
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*(void **) &old_jniRegisterNativeMethods = dlsym(RTLD_DEFAULT, sig);
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}
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}
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bool unhook_functions() {
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bool success = true;
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// Restore JNIEnv
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if (g_ctx->env->functions == new_functions) {
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g_ctx->env->functions = old_functions;
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if (gClassRef) {
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g_ctx->env->DeleteGlobalRef(gClassRef);
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gClassRef = nullptr;
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class_getName = nullptr;
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}
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}
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// Do NOT call the destructor
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operator delete(jni_method_map);
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// Directly unmap the whole memory block
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jni_hook::memory_block::release();
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// Unhook JNI methods
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for (const auto &[clz, methods] : *jni_hook_list) {
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if (!methods.empty() && old_jniRegisterNativeMethods(
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g_ctx->env, clz.data(), methods.data(), methods.size()) != 0) {
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LOGE("zygisk: Failed to restore JNI hook of class [%s]\n", clz.data());
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success = false;
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}
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}
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delete jni_hook_list;
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// Unhook xhook
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for (const auto &[path, sym, old_func] : *xhook_list) {
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if (xhook_register(path, sym, *old_func, nullptr) != 0) {
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LOGE("zygisk: Failed to register xhook [%s]\n", sym);
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success = false;
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}
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}
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delete xhook_list;
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if (!hook_refresh()) {
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LOGE("zygisk: Failed to restore xhook\n");
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success = false;
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}
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return success;
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}
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