[移动开发]aosp集成frida-gadget

编译环境:
ubuntu 16.04.7 + nexus 6P

1. 首先编译aosp,并能成功刷机。

2. 配置frida-gadget到编译成功的源码路径下

去github下载两个版本的frida-gadget.so

下载完成后解压,并改名。注意文件名必须以lib开头。

mv frida-gadget-15.1.16-android-arm.so libfg15116arm.so
mv frida-gadget-15.1.16-android-arm64.so libfg15116arm64.so

然后分别push到编译好的aosp对应目录

mv libfg15116arm.so out/target/product/angler/system/lib/
mv libfg15116arm64.so out/target/product/angler/system/lib64/

接下来创建frida gadget库的配置文件。配置文件名前半部分需要和gadget库的文件名相同

touch out/target/product/angler/system/lib/libfg15116arm.config.so
touch out/target/product/angler/system/lib/libfg15116arm64.config.so

分别在其中写入如下内容

{
  "interaction": {
    "type": "script",
    "path": "/data/local/tmp/hook.js"
  }
}

3. 修改源代码,在fork子进程的时候注入frida-gadget

找到源代码frameworks/base/core/jni/com_android_internal_os_Zygote.cpp

可以看到在这里fork的子进程。
在 pid==0的判断条件下，末尾增加以下代码

/*
 * 在虚拟机，系统框架初始化完成之后，加载frida框架
 * 需要增加头文件的引用 #include <dlfcn.h>
 */
#if defined(__aarch64__) || defined(__arm__)
    {
        #if defined(__aarch64__)
            #define FRIDA_LIB "/system/lib64/libfg15116arm64.so"
        #else
            #define FRIDA_LIB "/system/lib/libfg15116arm.so"
        #endif
        const char *name = env->GetStringUTFChars(java_se_name, 0);
        void* frida = dlopen(FRIDA_LIB, RTLD_NOW);
        if(NULL == frida) {
            ALOGE("(%s) load frida-gadget(%s) failed, err= %d\n", name, FRIDA_LIB, errno);
        } else {
            ALOGI("(%s) load frida-gadget(%s) success\n", name, FRIDA_LIB);
        }
        env->ReleaseStringUTFChars(java_se_name, name);
    }
#endif

4. 编译并重新生成系统镜像

cd frameworks/base
mmm
make snod

5. 刷机后效果

6. 测试效果，load上一篇文章中的so

编写hook脚本

// 必须加载app自己创建的so,adb shell创建的会加载失败。原因暂时未知
function copyFileByLibc(i_file, o_file){
    const addr_fopen = Module.findExportByName('libc.so', 'fopen');
    const addr_fread = Module.findExportByName('libc.so', 'fread');
    const addr_fclose = Module.findExportByName('libc.so', 'fclose');
    const addr_fwrite = Module.findExportByName('libc.so', 'fwrite');

    // console.log('fopen:', addr_fopen, 'fputs', addr_fputs, 'fclose', addr_fclose);
    // 构建函数
    const fopen = new NativeFunction(addr_fopen, 'pointer', ['pointer', 'pointer']);
    const fclose = new NativeFunction(addr_fclose, 'int', ['pointer']);
    const fread = new NativeFunction(addr_fread, 'int', ['pointer', 'int', 'int', 'pointer']);
    const fwrite = new NativeFunction(addr_fwrite, 'int', ['pointer', 'int', 'int', 'pointer']);

    const in_filename = Memory.allocUtf8String(i_file);
    const in_mode = Memory.allocUtf8String("rb");
    const in_file = fopen(in_filename, in_mode);

    const out_filename = Memory.allocUtf8String(o_file);
    const out_mode =  Memory.allocUtf8String("wb");
    const out_file = fopen(out_filename, out_mode);
    const read_size = 1024
    const buffer = Memory.alloc(read_size);
    while (true){
        const len = fread(buffer, 1, read_size, in_file);
        if(len === 0){
            break
        }
        fwrite(buffer, 1, len, out_file);
    }
    fclose(in_file);
    fclose(out_file);
}


function main(){
    if(Java.available){
        Java.perform(function (){
        var System = Java.use("java.lang.System");
        var clz = Java.use("com.h0p1.xposeddemo.MainActivity");
        clz.testOne.implementation = function (){
            var currentApplication = Java.use('android.app.ActivityThread').currentApplication();
            var context = currentApplication.getApplicationContext();
            var libs = context.getDir("tt", 0x0000);
            var target_so = libs.getAbsolutePath() + "/libhookso.so";
            copyFileByLibc("/data/local/tmp/libhookso.so", target_so);
            System.load(target_so);
        }
        })
    }
}
// 不能立即hook，不加延迟app启动就会崩溃
setTimeout(main, 500)

把脚本推到手机上

adb push code.js /data/local/tmp/hook.js

重新打开app，效果如下:

参考文章:

1.ubuntu 20.04系统AOSP(Android 11)集成Frida