android native怎么hook 安卓 native hook

作 者: malokch
 

说明:
安卓系统的可执行对象有两个世界,一个是Linux Native世界,一个是Java世界.两个世界能够通过jvm产生交互,具体来说就是通过jni技术进行互相干涉.但是在正常情况下,只能在Java世界通过jni调用native方法,二native不能在没有任何java上的支持下干涉java世界.
在一些应用中,我们需要对一个app的java世界进行干涉.再说到linux上的进程注入技术,已不用我多讲,但是传统的linux进程注入技术在安卓上只能进入目标进程的native世界.
于是本教程是要注入别的进程,并hook java世界的java 方法!
文章长,详情见附件

注入安卓进程,并hook java世界的方法

说明:
安卓系统的可执行对象有两个世界,一个是Linux Native世界,一个是Java世界.两个世界能够通过jvm产生交互,具体来说就是通过jni技术进行互相干涉.但是在正常情况下,只能在Java世界通过jni调用native方法,二native不能在没有任何java上的支持下干涉java世界.

在一些应用中,我们需要对一个app的java世界进行干涉.再说到linux上的进程注入技术,已不用我多讲,但是传统的linux进程注入技术在安卓上只能进入目标进程的native世界.

于是本教程是要注入别的进程,并hook java世界的java 方法!

条件:

1) 手机已root
2) 布置好了的ndk环境
3) 网友贡献的inject代码

由于安卓上的进程注入网上已经有很多方案了,这里就不列举了,这里就假设读者已经能够将so注入到别的进程并顺利运行了.

首先贴一下这次的目标
代码:
package com.example.testar;

import java.lang.reflect.Field;
    import java.util.HashMap;
    import java.util.Map;

    import dalvik.system.DexClassLoader;
    import android.net.wifi.WifiInfo;
    import android.net.wifi.WifiManager;
    import android.os.Bundle;
    import android.app.Activity;
    import android.content.Context;
    import android.text.GetChars;
    import android.util.Log;
    import android.view.Menu;
    import android.view.View;
    import android.widget.Button;

    public class MainActivity extends Activity {
        private final Map<String, ClassLoader> mLoaders = new HashMap<String, ClassLoader>();

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Button btn = (Button) findViewById(R.id.button1);
            btn.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
                    WifiInfo info = wifi.getConnectionInfo();
                    System.out.println("Wifi mac :" + info.getMacAddress());
                    System.out.println("return " + test());
                }
            });
        }

        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            // Inflate the menu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.main, menu);
            return true;
        }

        private String test() {
            return "real";
        }
    }
我们的目标是上面的test()方法,我们要改变其返回值.
接下来看看我们要注入到目标进程的so.cpp, MethodHooker.cpp
代码:
so.cpp:
#include "jni.h"
#include "android_runtime/AndroidRuntime.h"
#include "android/log.h"
#include "stdio.h"
#include "stdlib.h"
#include "MethodHooker.h"
#include <utils/CallStack.h>
#include "art.h"
#define log(a,b) __android_log_write(ANDROID_LOG_INFO,a,b); // LOG Ѝ:info
#define log_(b) __android_log_write(ANDROID_LOG_INFO,"JNI_LOG_INFO",b); // LOG Ѝ:info
extern "C" void InjectInterface(char*arg){
    log_("*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*");
    log_("*-*-*-*-*-* Injected so *-*-*-*-*-*-*-*");
    log_("*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*");
    Hook();
    log_("*-*-*-*-*-*-*- End -*-*-*-*-*-*-*-*-*-*");
}

extern "C" JNIEXPORT jstring JNICALL Java_com_example_testar_InjectApplication_test(JNIEnv *env, jclass clazz)
{
    Abort_();
    return env->NewStringUTF("haha ");;
}


MethodHooker.cpp:
#include "MethodHooker.h"
#include "jni.h"
#include "android_runtime/AndroidRuntime.h"
#include "android/log.h"
#include "stdio.h"
#include "stdlib.h"
#include "native.h"
#include <dlfcn.h>
#define ANDROID_SMP 0
#include "Dalvik.h"
#include "alloc/Alloc.h"

#include "art.h"

#define ALOG(...) __android_log_print(ANDROID_LOG_VERBOSE, __VA_ARGS__)

static bool g_bAttatedT;
static JavaVM *g_JavaVM;

void init()
{
    g_bAttatedT = false;
    g_JavaVM = android::AndroidRuntime::getJavaVM();
}

static JNIEnv *GetEnv()
{
 int status;
    JNIEnv *envnow = NULL;
    status = g_JavaVM->GetEnv((void **)&envnow, JNI_VERSION_1_4);
    if(status < 0)
    {
        status = g_JavaVM->AttachCurrentThread(&envnow, NULL);
        if(status < 0)
        {
            return NULL;
        }
        g_bAttatedT = true;
    }
    return envnow;
}

static void DetachCurrent()
{
    if(g_bAttatedT)
    {
        g_JavaVM->DetachCurrentThread();
    }
}

static int computeJniArgInfo(const DexProto* proto)
{
    const char* sig = dexProtoGetShorty(proto);
    int returnType, jniArgInfo;
    u4 hints;

    /* The first shorty character is the return type. */
    switch (*(sig++)) {
    case 'V':
        returnType = DALVIK_JNI_RETURN_VOID;
        break;
    case 'F':
        returnType = DALVIK_JNI_RETURN_FLOAT;
        break;
    case 'D':
        returnType = DALVIK_JNI_RETURN_DOUBLE;
        break;
    case 'J':
        returnType = DALVIK_JNI_RETURN_S8;
        break;
    case 'Z':
    case 'B':
        returnType = DALVIK_JNI_RETURN_S1;
        break;
    case 'C':
        returnType = DALVIK_JNI_RETURN_U2;
        break;
    case 'S':
        returnType = DALVIK_JNI_RETURN_S2;
        break;
    default:
        returnType = DALVIK_JNI_RETURN_S4;
        break;
    }

    jniArgInfo = returnType << DALVIK_JNI_RETURN_SHIFT;

    hints = dvmPlatformInvokeHints(proto);

    if (hints & DALVIK_JNI_NO_ARG_INFO) {
        jniArgInfo |= DALVIK_JNI_NO_ARG_INFO;
    } else {
        assert((hints & DALVIK_JNI_RETURN_MASK) == 0);
        jniArgInfo |= hints;
    }

    return jniArgInfo;
}

int ClearException(JNIEnv *jenv){
    jthrowable exception = jenv->ExceptionOccurred();
    if (exception != NULL) {
        jenv->ExceptionDescribe();
        jenv->ExceptionClear();
        return true;
    }
    return false;
}

bool isArt(){
    return true;
}

static jclass findAppClass(JNIEnv *jenv,const char *apn){
    //������oaders
    jclass clazzApplicationLoaders = jenv->FindClass("android/app/ApplicationLoaders");
    jthrowable exception = jenv->ExceptionOccurred();
    if (ClearException(jenv)) {
        ALOG("Exception","No class : %s", "android/app/ApplicationLoaders");
        return NULL;
    }
    jfieldID fieldApplicationLoaders = jenv->GetStaticFieldID(clazzApplicationLoaders,"gApplicationLoaders","Landroid/app/ApplicationLoaders;");
    if (ClearException(jenv)) {
        ALOG("Exception","No Static Field :%s","gApplicationLoaders");
        return NULL;
    }
    jobject objApplicationLoaders = jenv->GetStaticObjectField(clazzApplicationLoaders,fieldApplicationLoaders);
    if (ClearException(jenv)) {
        ALOG("Exception","GetStaticObjectField is failed [%s","gApplicationLoaders");
        return NULL;
    }
    jfieldID fieldLoaders = jenv->GetFieldID(clazzApplicationLoaders,"mLoaders","Ljava/util/Map;");
    if (ClearException(jenv)) {
        ALOG("Exception","No Field :%s","mLoaders");
        return NULL;
    }
    jobject objLoaders = jenv->GetObjectField(objApplicationLoaders,fieldLoaders);
    if (ClearException(jenv)) {
        ALOG("Exception","No object :%s","mLoaders");
        return NULL;
    }
    //̡ȡmap֐Ķalues
    jclass clazzHashMap = jenv->GetObjectClass(objLoaders);
    jmethodID methodValues = jenv->GetMethodID(clazzHashMap,"values","()Ljava/util/Collection;");
    jobject values = jenv->CallObjectMethod(objLoaders,methodValues);

    jclass clazzValues = jenv->GetObjectClass(values);
    jmethodID methodToArray = jenv->GetMethodID(clazzValues,"toArray","()[Ljava/lang/Object;");
    if (ClearException(jenv)) {
        ALOG("Exception","No Method:%s","toArray");
        return NULL;
    }

    jobjectArray classLoaders = (jobjectArray)jenv->CallObjectMethod(values,methodToArray);
    if (ClearException(jenv)) {
        ALOG("Exception","CallObjectMethod failed :%s","toArray");
        return NULL;
    }

        int size = jenv->GetArrayLength(classLoaders);

        for(int i = 0 ; i < size ; i ++){
            jobject classLoader = jenv->GetObjectArrayElement(classLoaders,i);
            jclass clazzCL = jenv->GetObjectClass(classLoader);
            jmethodID loadClass = jenv->GetMethodID(clazzCL,"loadClass","(Ljava/lang/String;)Ljava/lang/Class;");
            jstring param = jenv->NewStringUTF(apn);
            jclass tClazz = (jclass)jenv->CallObjectMethod(classLoader,loadClass,param);
            if (ClearException(jenv)) {
                ALOG("Exception","No");
                continue;
            }
            return tClazz;
        }
    ALOG("Exception","No");
    return NULL;
}



bool HookDalvikMethod(jmethodID jmethod){
    Method *method = (Method*)jmethod;
    //ؼ!!Ŀ귽ОĎnative
    SET_METHOD_FLAG(method, ACC_NATIVE);

    int argsSize = dvmComputeMethodArgsSize(method);
    if (!dvmIsStaticMethod(method))
        argsSize++;

    method->registersSize = method->insSize = argsSize;

    if (dvmIsNativeMethod(method)) {
        method->nativeFunc = dvmResolveNativeMethod;
        method->jniArgInfo = computeJniArgInfo(&method->prototype);
    }
}

bool ClassMethodHook(HookInfo info){

    JNIEnv *jenv = GetEnv();

    jclass clazzTarget = jenv->FindClass(info.tClazz);
    if (ClearException(jenv)) {
        ALOG("Exception","ClassMethodHook[Can't find class:%s in bootclassloader",info.tClazz);

        clazzTarget = findAppClass(jenv,info.tClazz);
        if(clazzTarget == NULL){
            ALOG("Exception","%s","Error in findAppClass");
            return false;
        }
    }

    jmethodID method = jenv->GetMethodID(clazzTarget,info.tMethod,info.tMeihodSig);
    if(method==NULL){
        ALOG("Exception","ClassMethodHook[Can't find method:%s",info.tMethod);
        return false;
    }

    if(isArt()){
        HookArtMethod(jenv,method);
    }else{
        HookDalvikMethod(method);
    }

    JNINativeMethod gMethod[] = {
        {info.tMethod, info.tMeihodSig, info.handleFunc},
    };

    //funcΪNULLʱהА������������չɍ
    if(info.handleFunc != NULL){
        //ؼ!!Ŀ귽؁הҥĮative
        if (jenv->RegisterNatives(clazzTarget, gMethod, 1) < 0) {
            ALOG("RegisterNatives","err");
            return false;
        }
    }

    DetachCurrent();
    return true;
}

int Hook(){
    init();
    void* handle = dlopen("/data/local/libTest.so",RTLD_NOW);
    const char *dlopen_error = dlerror();
    if(!handle){
        ALOG("Error","cannt load plugin :%s",dlopen_error);
        return -1;
    }
    SetupFunc setup = (SetupFunc)dlsym(handle,"getpHookInfo");
    const char *dlsym_error = dlerror();
    if (dlsym_error) {
        ALOG("Error","Cannot load symbol 'getpHookInfo' :%s" , dlsym_error);
        dlclose(handle);
        return 1;
    }

    HookInfo *hookInfo;
    setup(&hookInfo);

    ALOG("LOG","Target Class:%s",hookInfo[0].tClazz);
    ALOG("LOG","Target Method:%s",hookInfo[0].tMethod);

    ClassMethodHook(hookInfo[0]);
}

以下是我们想要的目标进程java世界执行的我们自定义的代码
代码:

libTest.so
#include "native.h"
#include <android/log.h>
#include "stdio.h"
#include "stdlib.h"
#include "MethodHooker.h"       
#define log(a,b) __android_log_print(ANDROID_LOG_VERBOSE,a,b); // LOG Ѝ:info
    #define log_(b) __android_log_print(ANDROID_LOG_VERBOSE,"JNI_LOG_INFO",b); // LOG Ѝ:info

    int getpHookInfo(HookInfo** pInfo);

    JNIEXPORT void JNICALL Java_com_example_testar_InjectClassloader_hookMethodNative
      (JNIEnv * jenv, jobject jboj, jobject jobj, jclass jclazz, jint slot)
    {
        //log("TestAE","start Inject other process");
    }

    JNIEXPORT jstring JNICALL test(JNIEnv *env, jclass clazz)  
    {  
        //__android_log_print(ANDROID_LOG_VERBOSE, "tag", "call <native_printf> in java");
        return (*env)->NewStringUTF(env,"haha ");;
    }

    HookInfo hookInfos[] = {
            {"android/net/wifi/WifiInfo","getMacAddress","()Ljava/lang/String;",(void*)test},
            //{"com/example/testar/MainActivity","test","()Ljava/lang/String;",(void*)test},
            //{"android/app/ApplicationLoaders","getText","()Ljava/lang/CharSequence;",(void*)test},
    };

    int getpHookInfo(HookInfo** pInfo){
        *pInfo = hookInfos;
        return sizeof(hookInfos) / sizeof(hookInfos[0]);
    }

程序大致的流程是这样的,首先将so.so注入到目标进程,执行里面的Hook()函数,然后Hook()加载libTest.so,获取里面定义的Hook信息.接着用ClassMethodHook挂钩java世界的方法.

关键一：

从native世界进入java世界.熟悉jni编程的都知道,java到native的桥梁是JNIEnv,我们只要获得一个JNIEnv就能进入到java世界了.突破点就在AndroidRuntime,android::AndroidRuntime::getJavaVM();这个静态方法能够获取一个JavaVM, JavaVM->GetEnv方法能够获得一个JNIEnv了.JNIEnv是和线程相关的,使用前一定记得将其附加到当前进程,也要在适当的时候将其销毁.

关键二：

怎么影响内存里的java代码,这个情况替换内存是不现实的,但是可以取巧.我们知道java代码里将一个方法声明为native方法时,对此函数的调用就会到native世界里找.我们何不在运行时将一个不是native的方法修改成native方法呢?这是可以做到的,看着段代码
代码:

bool HookDalvikMethod(jmethodID jmethod){
Method *method = (Method*)jmethod;
SET_METHOD_FLAG(method, ACC_NATIVE);

int argsSize = dvmComputeMethodArgsSize(method);
    if (!dvmIsStaticMethod(method))
        argsSize++;

method->registersSize = method->insSize = argsSize;

    if (dvmIsNativeMethod(method)) {
        method->nativeFunc = dvmResolveNativeMethod;
        method->jniArgInfo = computeJniArgInfo(&method->prototype);
        }
}

Jni反射调用java方法时要用到一个jmethodID指针,这个指针在Dalvik里其实就是Method类,通过修改这个类的一些属性就可以实现在运行时将一个方法修改成native方法.

SET_METHOD_FLAG(method, ACC_NATIVE);

就是这么做的,其后面的代码就是设定native函数的参数占用内存大小统计.

也许你发现了,虽然将其修改成一个native方法了,但是这个方法对应的native代码在那里呢?这样做
代码:

if (jenv->RegisterNatives(clazzTarget, gMethod, 1) < 0) {
        ALOG("RegisterNatives","err");
        return false;
    }

可以将一个native函数绑定到一个java的native方法

这样就能够实现开始的目标了!

我这里讲得是有点粗略了,但是这个技术牵涉到的知识太多了,主要是给老鸟参考的,小菜们拿来用用就好,要是要讲得小菜们都能明白,就不知要讲到何年何月了.还有就是上面的art环境的代码是跑不起来的,等我后面有空完善了再发一次吧!

 

//############### 14.16.17更新 ##########################
之前没有提到调用原来的方法的方法,方法是这样，直接内存拷贝存起来
代码:

uint mlen = sizeof(Method);
  Method *oldMeth = (Method*)malloc(mlen);
  memcpy(oldMeth,method,mlen);
  info->odlMethod = oldMeth;
  info->curMethod = method;

调用原来的方法就把内存拷回去，调用后再hook一次
代码:

memcpy(hi->curMethod,hi->odlMethod,mlen);

  jmethodID om = (jmethodID)hi->curMethod;
  jenv->CallVoidMethod(me,om,gDevice_Sensors);

  ClassMethodHook(jenv,&baiduhookInfos[0]);