mirror of
https://github.com/topjohnwu/Magisk.git
synced 2024-12-26 12:27:38 +00:00
276 lines
8.7 KiB
C++
276 lines
8.7 KiB
C++
#include <jni.h>
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#include <xhook.h>
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#include <utils.hpp>
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#include <flags.hpp>
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#include <daemon.hpp>
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#include "inject.hpp"
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using namespace std;
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#define DCL_HOOK_FUNC(ret, func, ...) \
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static ret (*old_##func)(__VA_ARGS__); \
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static ret new_##func(__VA_ARGS__)
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#define DCL_JNI_FUNC(name) \
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static const JNINativeMethod *name##_orig = nullptr; \
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extern const JNINativeMethod name##_methods[]; \
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extern const int name##_methods_num;
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namespace {
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struct HookContext {
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int pid;
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bool do_hide;
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};
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// JNI method declarations
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DCL_JNI_FUNC(nativeForkAndSpecialize)
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DCL_JNI_FUNC(nativeSpecializeAppProcess)
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DCL_JNI_FUNC(nativeForkSystemServer)
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}
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// For some reason static vectors won't work, use pointers instead
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static vector<tuple<const char *, const char *, void **>> *xhook_list;
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static vector<JNINativeMethod> *jni_list;
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static JavaVM *g_jvm;
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static int prev_fork_pid = -1;
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static HookContext *current_ctx;
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#define HOOK_JNI(method) \
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if (newMethods[i].name == #method##sv) { \
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auto orig = new JNINativeMethod(); \
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memcpy(orig, &newMethods[i], sizeof(JNINativeMethod)); \
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method##_orig = orig; \
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jni_list->push_back(newMethods[i]); \
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for (int j = 0; j < method##_methods_num; ++j) { \
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if (strcmp(newMethods[i].signature, method##_methods[j].signature) == 0) { \
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newMethods[i] = method##_methods[j]; \
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LOGI("hook: replaced #" #method "\n"); \
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++hooked; \
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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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DCL_HOOK_FUNC(int, jniRegisterNativeMethods,
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JNIEnv *env, const char *className, const JNINativeMethod *methods, int numMethods) {
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LOGD("hook: jniRegisterNativeMethods %s", className);
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unique_ptr<JNINativeMethod[]> newMethods;
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int hooked = 0;
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if (g_jvm == nullptr) {
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// Save for later unhooking
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env->GetJavaVM(&g_jvm);
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}
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if (className == "com/android/internal/os/Zygote"sv) {
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newMethods = make_unique<JNINativeMethod[]>(numMethods);
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memcpy(newMethods.get(), methods, sizeof(JNINativeMethod) * numMethods);
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for (int i = 0; i < numMethods && hooked < 3; ++i) {
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HOOK_JNI(nativeForkAndSpecialize);
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HOOK_JNI(nativeSpecializeAppProcess);
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HOOK_JNI(nativeForkSystemServer);
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}
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}
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return old_jniRegisterNativeMethods(env, className, newMethods.get() ?: methods, numMethods);
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}
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DCL_HOOK_FUNC(int, fork) {
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if (prev_fork_pid < 0)
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return old_fork();
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// Skip an actual fork and return the previous fork result
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int pid = prev_fork_pid;
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prev_fork_pid = -1;
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return pid;
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}
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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 (current_ctx && current_ctx->do_hide) {
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// Ask magiskd to hide ourselves before switching context
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// because magiskd socket is not accessible on Android 8.0+
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remote_request_hide();
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LOGD("hook: process successfully hidden\n");
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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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static 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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static int pre_specialize_fork() {
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// First block SIGCHLD, unblock after original fork is done
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sigmask(SIG_BLOCK, SIGCHLD);
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prev_fork_pid = old_fork();
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return prev_fork_pid;
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}
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// -----------------------------------------------------------------
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static void nativeSpecializeAppProcess_pre(HookContext *ctx,
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JNIEnv *env, jclass clazz, jint &uid, jint &gid, jintArray &gids, jint &runtime_flags,
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jobjectArray &rlimits, jint &mount_external, jstring &se_info, jstring &nice_name,
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jboolean &is_child_zygote, jstring &instruction_set, jstring &app_data_dir,
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jboolean &is_top_app, jobjectArray &pkg_data_info_list,
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jobjectArray &whitelisted_data_info_list, jboolean &mount_data_dirs,
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jboolean &mount_storage_dirs) {
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current_ctx = ctx;
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const char *process = env->GetStringUTFChars(nice_name, nullptr);
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LOGD("hook: %s %s\n", __FUNCTION__, process);
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if (mount_external != 0 /* TODO: Handle MOUNT_EXTERNAL_NONE cases */
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&& remote_check_hide(uid, process)) {
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ctx->do_hide = true;
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LOGI("hook: [%s] should be hidden\n", process);
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}
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env->ReleaseStringUTFChars(nice_name, process);
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}
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static void nativeSpecializeAppProcess_post(HookContext *ctx, JNIEnv *env, jclass clazz) {
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LOGD("hook: %s\n", __FUNCTION__);
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if (ctx->do_hide)
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self_unload();
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current_ctx = nullptr;
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}
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// -----------------------------------------------------------------
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static void nativeForkAndSpecialize_pre(HookContext *ctx,
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JNIEnv *env, jclass clazz, jint &uid, jint &gid, jintArray &gids, jint &runtime_flags,
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jobjectArray &rlimits, jint &mount_external, jstring &se_info, jstring &nice_name,
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jintArray fds_to_close, jintArray fds_to_ignore, /* These 2 arguments are unique to fork */
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jboolean &is_child_zygote, jstring &instruction_set, jstring &app_data_dir,
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jboolean &is_top_app, jobjectArray &pkg_data_info_list,
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jobjectArray &whitelisted_data_info_list, jboolean &mount_data_dirs,
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jboolean &mount_storage_dirs) {
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// Do our own fork before loading any 3rd party code
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ctx->pid = pre_specialize_fork();
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if (ctx->pid != 0)
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return;
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nativeSpecializeAppProcess_pre(
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ctx, env, clazz, uid, gid, gids, runtime_flags, rlimits, mount_external, se_info,
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nice_name, is_child_zygote, instruction_set, app_data_dir, is_top_app,
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pkg_data_info_list, whitelisted_data_info_list, mount_data_dirs, mount_storage_dirs);
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}
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static void nativeForkAndSpecialize_post(HookContext *ctx, JNIEnv *env, jclass clazz) {
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// Unblock SIGCHLD in case the original method didn't
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sigmask(SIG_UNBLOCK, SIGCHLD);
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if (ctx->pid != 0)
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return;
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nativeSpecializeAppProcess_post(ctx, env, clazz);
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}
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// -----------------------------------------------------------------
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static void nativeForkSystemServer_pre(HookContext *ctx,
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JNIEnv *env, jclass clazz, uid_t &uid, gid_t &gid, jintArray &gids, jint &runtime_flags,
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jobjectArray &rlimits, jlong &permitted_capabilities, jlong &effective_capabilities) {
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// Do our own fork before loading any 3rd party code
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ctx->pid = pre_specialize_fork();
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if (ctx->pid != 0)
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return;
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current_ctx = ctx;
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LOGD("hook: %s\n", __FUNCTION__);
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}
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static void nativeForkSystemServer_post(HookContext *ctx, JNIEnv *env, jclass clazz) {
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// Unblock SIGCHLD in case the original method didn't
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sigmask(SIG_UNBLOCK, SIGCHLD);
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if (ctx->pid != 0)
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return;
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LOGD("hook: %s\n", __FUNCTION__);
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current_ctx = nullptr;
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}
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// -----------------------------------------------------------------
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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("hook: xhook success\n");
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return true;
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} else {
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LOGE("hook: 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(PATH_REGEX, NAME) \
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hook_register(PATH_REGEX, #NAME, (void*) new_##NAME, (void **) &old_##NAME)
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void hook_functions() {
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#ifdef 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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xhook_list = new remove_pointer_t<decltype(xhook_list)>();
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jni_list = new remove_pointer_t<decltype(jni_list)>();
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XHOOK_REGISTER(".*\\libandroid_runtime.so$", jniRegisterNativeMethods);
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XHOOK_REGISTER(".*\\libandroid_runtime.so$", fork);
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XHOOK_REGISTER(".*\\libandroid_runtime.so$", selinux_android_setcontext);
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hook_refresh();
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}
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bool unhook_functions() {
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JNIEnv* env;
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if (g_jvm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK)
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return false;
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// Unhook JNI methods
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if (!jni_list->empty() && old_jniRegisterNativeMethods(env,
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"com/android/internal/os/Zygote",
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jni_list->data(), jni_list->size()) != 0) {
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LOGE("hook: Failed to register JNI hook\n");
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return false;
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}
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delete jni_list;
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// Unhook xhook
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for (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("hook: Failed to register hook \"%s\"\n", sym);
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return false;
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}
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}
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delete xhook_list;
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return hook_refresh();
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}
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#include "jni_hooks.hpp"
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