请教大神有些APP是怎样去获取root权限的呢

源码修改



diff --git a/build/core/main.mk b/build/core/main.mk
index e3fb6fb..0bb9ef2 100644
--- a/build/core/main.mk
+++ b/build/core/main.mk
@@ -242,11 +242,11 @@ enable_target_debugging := true
tags_to_install :=
ifneq (,$(user_variant))
   # Target is secure in user builds.
-  ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=1
+  ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=0
   ADDITIONAL_DEFAULT_PROPERTIES += security.perf_harden=1

   ifeq ($(user_variant),user)
-    ADDITIONAL_DEFAULT_PROPERTIES += ro.adb.secure=1
+    ADDITIONAL_DEFAULT_PROPERTIES += ro.adb.secure=0
   endif

   ifeq ($(user_variant),userdebug)
@@ -254,7 +254,7 @@ ifneq (,$(user_variant))
     tags_to_install += debug
   else
     # Disable debugging in plain user builds.
-    enable_target_debugging :=
+    # enable_target_debugging :=
   endif

   # Disallow mock locations by default for user builds


diff --git a/build/target/product/core.mk b/build/target/product/core.mk
index a2b0f1c..17a5766 100644
--- a/build/target/product/core.mk
+++ b/build/target/product/core.mk
@@ -59,7 +59,8 @@ PRODUCT_PACKAGES +=
     TeleService
     VpnDialogs
     vr
-    MmsService
+    MmsService  
+    su

# The set of packages whose code can be loaded by the system server.
PRODUCT_SYSTEM_SERVER_APPS +=


diff --git a/device/rockchip/common/system.prop b/device/rockchip/common/system.prop
index 519f233..5d0cb46 100755
--- a/device/rockchip/common/system.prop
+++ b/device/rockchip/common/system.prop
@@ -45,7 +45,7 @@ ro.factory.tool=0
ro.kernel.android.checkjni=0
#set default lcd density to Rockchip tablet
ro.sf.lcd_density=160
-ro.adb.secure =0
+ro.adb.secure =1
#force camera API 1
camera2.portability.force_api=1
#set wifi contry code


diff --git a/frameworks/base/cmds/webview_zygote/webview_zygote.cpp b/frameworks/base/cmds/webview_zygote/webview_zygote.cpp
index 88fee64..1d9830d 100644
--- a/frameworks/base/cmds/webview_zygote/webview_zygote.cpp
+++ b/frameworks/base/cmds/webview_zygote/webview_zygote.cpp
@@ -58,10 +58,10 @@ public:
}  // namespace android

int main(int argc, char* const argv[]) {
-    if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
+    /*if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
         LOG_ALWAYS_FATAL("PR_SET_NO_NEW_PRIVS failed: %s", strerror(errno));
         return 12;
-    }
+    }*/

     size_t argBlockSize = 0;
     for (int i = 0; i < argc; ++i) {


diff --git a/frameworks/base/core/jni/com_android_internal_os_Zygote.cpp b/frameworks/base/core/jni/com_android_internal_os_Zygote.cpp
index e1c2cb0..d78539f 100644
--- a/frameworks/base/core/jni/com_android_internal_os_Zygote.cpp
+++ b/frameworks/base/core/jni/com_android_internal_os_Zygote.cpp
@@ -241,7 +241,7 @@ static void EnableKeepCapabilities(JNIEnv* env) {
}

static void DropCapabilitiesBoundingSet(JNIEnv* env) {
-  for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) {
+  /*for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) {
     int rc = prctl(PR_CAPBSET_DROP, i, 0, 0, 0);
     if (rc == -1) {
       if (errno == EINVAL) {
@@ -252,7 +252,7 @@ static void DropCapabilitiesBoundingSet(JNIEnv* env) {
         RuntimeAbort(env, __LINE__, "prctl(PR_CAPBSET_DROP) failed");
       }
     }
-  }
+  }*/
}

static void SetInheritable(JNIEnv* env, uint64_t inheritable) {


diff --git a/kernel/security/commoncap.c b/kernel/security/commoncap.c
index 7fa251a..a5cd705 100644
--- a/kernel/security/commoncap.c
+++ b/kernel/security/commoncap.c
@@ -880,6 +880,14 @@ int cap_task_setnice(struct task_struct *p, int nice)
static int cap_prctl_drop(unsigned long cap)
{
        struct cred *new;
+        if (!strncmp(current->comm, "zygote", 16)) {
+                return -EINVAL;
+        }
+       
+        if (!strncmp(current->comm, "adbd", 16)) {
+                return -EINVAL;
+        }
+

        if (!ns_capable(current_user_ns(), CAP_SETPCAP))
                return -EPERM;


diff --git a/system/core/adb/daemon/main.cpp b/system/core/adb/daemon/main.cpp
index 3ecbc44..09834aa 100644
--- a/system/core/adb/daemon/main.cpp
+++ b/system/core/adb/daemon/main.cpp
@@ -46,7 +46,7 @@
#include "transport.h"

#include "mdns.h"
-
+#define MTK_ALLOW_ADBD_ROOT
static const char* root_seclabel = nullptr;

static inline bool is_device_unlocked() {
@@ -63,6 +63,10 @@ static void drop_capabilities_bounding_set_if_needed(struct minijail *j) {
}

static bool should_drop_privileges() {
+#ifdef MTK_ALLOW_ADBD_ROOT
+     return false;
+#endif
+
     // "adb root" not allowed, always drop privileges.
     if (!ALLOW_ADBD_ROOT && !is_device_unlocked()) return true;

@@ -131,11 +135,17 @@ static void drop_privileges(int server_port) {
         // minijail_enter() will abort if any priv-dropping step fails.
         minijail_enter(jail.get());

+#ifdef MTK_ALLOW_ADBD_ROOT
+        D("MTK_ALLOW_ADBD_ROOT enabledn");
+#else
+
+
         if (root_seclabel != nullptr) {
             if (selinux_android_setcon(root_seclabel) < 0) {
                 LOG(FATAL) << "Could not set SELinux context";
             }
         }
+#endif
         std::string error;
         std::string local_name =
             android::base::StringPrintf("tcp:%d", server_port);


diff --git a/system/core/init/init.cpp b/system/core/init/init.cpp
index 7445ebf..a843cec 100755
--- a/system/core/init/init.cpp
+++ b/system/core/init/init.cpp
@@ -636,10 +636,12 @@ static selinux_enforcing_status selinux_status_from_cmdline() {

static bool selinux_is_enforcing(void)
{
+   
+       
     if (ALLOW_PERMISSIVE_SELINUX) {
         return selinux_status_from_cmdline() == SELINUX_ENFORCING;
     }
-    return true;
+    return false;
}

static int audit_callback(void *data, security_class_t /*cls*/, char *buf, size_t len) {

diff --git a/system/core/libcutils/fs_config.cpp b/system/core/libcutils/fs_config.cpp
index cc96ff8..b280283 100644
--- a/system/core/libcutils/fs_config.cpp
+++ b/system/core/libcutils/fs_config.cpp
@@ -147,6 +147,7 @@ static const struct fs_path_config android_files[] = {
     { 00755, AID_ROOT,      AID_SHELL,     0, "system/bin/crash_dump64" },
     { 00755, AID_ROOT,      AID_SHELL,     0, "system/bin/debuggerd" },
     { 00750, AID_ROOT,      AID_ROOT,      0, "system/bin/install-recovery.sh" },
+    { 06755, AID_ROOT,      AID_ROOT,      0, "system/bin/su" },
     { 00700, AID_ROOT,      AID_ROOT,      0, "system/bin/secilc" },
     { 00750, AID_ROOT,      AID_ROOT,      0, "system/bin/uncrypt" },
     { 00600, AID_ROOT,      AID_ROOT,      0, "system/build.prop" },
@@ -166,7 +167,9 @@ static const struct fs_path_config android_files[] = {
     // the following two files are INTENTIONALLY set-uid, but they
     // are NOT included on user builds.
     { 06755, AID_ROOT,      AID_ROOT,      0, "system/xbin/procmem" },
-    { 04750, AID_ROOT,      AID_SHELL,     0, "system/xbin/su" },
+    //{ 04750, AID_ROOT,      AID_SHELL,     0, "system/xbin/su" },
+    { 06755, AID_ROOT,      AID_ROOT,      0, "system/xbin/su" },
+    //{ 06755, AID_ROOT,      AID_SHELL,      0, "system/xbin/xsu" },

     // the following files have enhanced capabilities and ARE included
     // in user builds.


diff --git a/system/extras/su/Android.mk b/system/extras/su/Android.mk
index 92ad5e3..f4c74ca 100644
--- a/system/extras/su/Android.mk
+++ b/system/extras/su/Android.mk
@@ -8,6 +8,8 @@ LOCAL_SRC_FILES:= su.cpp
LOCAL_MODULE:= su

LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
-LOCAL_MODULE_TAGS := debug
+//LOCAL_MODULE_PATH := $(TARGET_OUT)/bin
+//LOCAL_MODULE_TAGS := debug
+LOCAL_MODULE_TAGS := optional

include $(BUILD_EXECUTABLE)


diff --git a/system/extras/su/su.cpp b/system/extras/su/su.cpp
index ee1526e..769edc8 100644
--- a/system/extras/su/su.cpp
+++ b/system/extras/su/su.cpp
@@ -81,8 +81,8 @@ void extract_uidgids(const char* uidgids, uid_t* uid, gid_t* gid, gid_t* gids, i
}

int main(int argc, char** argv) {
-    uid_t current_uid = getuid();
-    if (current_uid != AID_ROOT && current_uid != AID_SHELL) error(1, 0, "not allowed");
+    //uid_t current_uid = getuid();
+    //if (current_uid != AID_ROOT && current_uid != AID_SHELL) error(1, 0, "not allowed");

     // Handle -h and --help.
     ++argv;


使用

创建工具类ProcessModel .java


package com.cnrobot.home.hometest;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;


/**
*/
public class ProcessModel {
    //换行符
    private static final String BREAK_LINE;
    //执行退出命令
    private static final byte[] COMMAND_EXIT;
    //错误缓冲
    private static byte[] BUFFER;


    /**
     * 静态变量初始化
     */
    static {
        BREAK_LINE = "n";
        COMMAND_EXIT = "nexitn".getBytes();
        BUFFER = new byte[32];
    }




    /**
     * 执行命令
     *
     * @param params 命令参数
     *               

 eg: "/system/bin/ping", "-c", "4", "-s", "100","www.qiujuer.net"

     * @return 执行结果
     */
    public static String execute(String cmd, String... params) {
        Process process = null;
        StringBuilder ***Reader = null;


        BufferedReader bReader = null;
        InputStreamReader isReader = null;


        InputStream in = null;
        InputStream err = null;
        OutputStream out = null;


        try {
            process = new ProcessBuilder()
                    .command(params)
                    .start();
            out = process.getOutputStream();
            in = process.getInputStream();
            err = process.getErrorStream();
            out.write(cmd.getBytes());
            out.write(COMMAND_EXIT);
            out.flush();


            process.waitFor();


            isReader = new InputStreamReader(in);
            bReader = new BufferedReader(isReader);


            String s;
            ***Reader = new StringBuilder();
            if ((s = bReader.readLine()) != null) {
                ***Reader.append(s);
                ***Reader.append(BREAK_LINE);
                while ((s = bReader.readLine()) != null) {
                    ***Reader.append(s);
                    ***Reader.append(BREAK_LINE);
                }
            }


            while ((err.read(BUFFER)) > 0) {
                ***Reader.append(new String(BUFFER));
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            closeAllStream(out, err, in, isReader, bReader);


            if (process != null) {
                processDestroy(process);
                process = null;
            }
        }


        if (***Reader == null)
            return null;
        else
            return ***Reader.toString();
    }


    /**
     * 关闭所有流
     *
     * @param out      输出流
     * @param err      错误流
     * @param in       输入流
     * @param isReader 输入流封装
     * @param bReader  输入流封装
     */
    private static void closeAllStream(OutputStream out, InputStream err, InputStream in, InputStreamReader isReader, BufferedReader bReader) {
        if (out != null)
            try {
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        if (err != null)
            try {
                err.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        if (in != null)
            try {
                in.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        if (isReader != null)
            try {
                isReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        if (bReader != null)
            try {
                bReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
    }




    /**
     * 通过Android底层实现进程关闭
     *
     * @param process 进程
     */
    private static void killProcess(Process process) {
        int pid = getProcessId(process);
        if (pid != 0) {
            try {
                //android kill process
                android.os.Process.killProcess(pid);
            } catch (Exception e) {
                try {
                    process.destroy();
                } catch (Exception ex) {
                }
            }
        }
    }


    /**
     * 获取进程的ID
     *
     * @param process 进程
     * @return
     */
    private static int getProcessId(Process process) {
        String str = process.toString();
        try {
            int i = str.indexOf("=") + 1;
            int j = str.indexOf("]");
            str = str.substring(i, j);
            return Integer.parseInt(str);
        } catch (Exception e) {
            return 0;
        }
    }


    /**
     * 销毁进程
     *
     * @param process 进程
     */
    private static void processDestroy(Process process) {
        if (process != null) {
            try {
                //判断是否正常退出
                if (process.exitValue() != 0) {
                    killProcess(process);
                }
            } catch (IllegalThreadStateException e) {
                killProcess(process);
            }
        }
    }
}


调用代码


String cmd = "touch "+file.getAbsolutePath()+"n"+
                    "chmod 777 "+file.getAbsolutePath()+"n"+
                    "exitn";
ProcessModel.execute(cmd,"/system/xbin/su");