给应用添加Selinux配置的完整记录


公司人力吃紧,特别缺少C开发的同学,只能是我是一块砖,哪里需要哪里搬!记录一次Android系统完整的配置开启启动应用,并配置Selinux权限的过程!


1、添加应用程序在vendor目录,编译生成可执行文件test_abc在/system/bin/中;

这里开始是参考网上的修改,但发现编译后并不能将test_abc可执行文件打包到/system/bin中;

aaa@abc-0C:~/work/ATOS_Q/vendor/test$ cat Android.mk
LOCAL_PATH := $(call my-dir)

PRODUCT_PACKAGES += \
        test_abc
include $(call all-makefiles-under,$(LOCAL_PATH))


test_abc\目录下的文件:

Android.mk

test_abc.c

Android.mk文件:

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

LOCAL_SRC_FILES:= \
    test_abc.c

LOCAL_SHARED_LIBRARIES := \
    libcutils \
    libutils

LOCAL_C_INCLUDES += \
    bionic \

LOCAL_MODULE := test_abc
LOCAL_MODULE_TAGS := optional

LOCAL_MULTILIB := 64

include $(BUILD_EXECUTABLE)

test_abc.c中就是一个main方法,操作文件和socket;

解决test_abc不能打包到system/bin路径下的方法是将test_abc整个路径都移到了qcom的厂家路径下:


aaa@abc-0C:~/work/ATOS_Q/vendor/qcom/bonito/test_abc$ pwd
/home1/gwb/work/ATOS_Q/vendor/qcom/bonito/test_abc
aaa@abc-0C:~/work/ATOS_Q/vendor/qcom/bonito/test_abc$ ls
Android.mk  test_abc.c  


     23 #lyz add for test
     24 include vendor/xdja/test_abc/Android.mk



2、添加test_abc的权限定义:

aaa@abc-0C:~/work/ATOS_Q$ vi device/google/bonito-sepolicy/vendor/qcom/sdm710/file_contexts
     60 #lyz add for test
     61 /system/bin/test_abc u:object_r:test_abc_exec:s0



3、添加开机启动,修改./system/core/rootdir/init.rc

#lyz add for test
service test_abc /system/bin/test_abc
    class main
    oneshot
    seclabel u:r:test_abc:s0



4、添加te文件: 

aaa@abc-0C:~/work/ATOS_Q$ cat device/google/bonito-sepolicy/vendor/qcom/common/test_abc.te
type test_abc, domain, coredomain;
type test_abc_exec, file_type, system_file_type, exec_type;

init_daemon_domain(test_abc)



5、编译验证,查看dmesg开机日志:


[    9.191761] init: cannot setexeccon('u:r:test_abc_exec:s0') for test_abc: Invalid argument

问题应该是test_abc.te的路径不对,导致init启动时并不认识标签"u:r:test_abc_exec:s0"

修改第四步,将test_abc.te文件移到路径下/device/google/bonito-sepolicy/private 路径下,重新编译版本,下载启动;
aaa@xdja-0C:~/work/ATOS_Q/device/google/bonito-sepolicy/private$ pwd
/home1/gwb/work/ATOS_Q/device/google/bonito-sepolicy/private



6、查看dmesg开机日志,终于出来期望的deny日志:

    Line 2077: [    9.178268] type=1400 audit(258.270:14): avc: denied { dac_override } for comm="test_abc" capability=1 scontext=u:r:test_abc:s0 tcontext=u:r:test_abc:s0 tclass=capability permissive=0
    Line 2078: [    9.178488] type=1400 audit(258.273:16): avc: denied { dac_override } for comm="test_abc" capability=1 scontext=u:r:test_abc:s0 tcontext=u:r:test_abc:s0 tclass=capability permissive=0 duplicate messages suppressed
    Line 2079: [    9.178500] type=1400 audit(258.273:17): avc: denied { create } for comm="test_abc" scontext=u:r:test_abc:s0 tcontext=u:r:test_abc:s0 tclass=tcp_socket permissive=0
    Line 2158: [    9.609626] type=1400 audit(258.273:17): avc: denied { create } for comm="test_abc" scontext=u:r:test_abc:s0 tcontext=u:r:test_abc:s0 tclass=tcp_socket permissive=0



7、修改test_abc.te 增加test_abc的相关权限,编译版本,重新进行验证:

#============= test_abc ==============

allow test_abc self:capability dac_override;

allow test_abc self:tcp_socket create;



8、解决/system不能root的问题:

E:\source\dual_os>adb root
restarting adbd as root

E:\source\dual_os>adb remount
W Disabling verity for /system
E Skipping /system
W Disabling verity for /vendor
E Skipping /vendor
W Disabling verity for /product
E Skipping /product
W No partitions to remount
/system/bin/remount exited with status 7
remount failed
system路径root失败!

解决:

首先进入开发者模式,开启OEM选项,

然后adb reboot bootloader

然后fastboot flashing unlock

然后fastboot getvar unlocked

等待结果一般会出现yes,如果不是yes可能又需要百度解决这个问题

之后重启,然后adb root , adb disable-verity, 然后重启 adb remount就可以挂载了 


adb remount失败,可以使用diable-verity

C:\Users\li>adb disable-verity

verity is already disabled

using overlayfs

Now reboot your device for settings to take effect


E:\source\dual_os>adb root
restarting adbd as root

E:\source\dual_os>adb remount
remount succeeded

E:\source\dual_os>

E:\source\dual_os>adb push E:\source\dual_os\test_abc /system/bin
120 KB/s (11560 bytes in 0.093s)

E:\source\dual_os>adb shell reboot

E:\source\dual_os>



Selinux的概念甚多,理解起来还是很费劲的!并且需要有Linux内核的基础知识,总归来说是打通任督二脉的一件事,多多学习总是没有坏处的!


呱牛笔记

参考 :

https://source.android.google.cn/security/selinux/customize

https://www.cnblogs.com/schips/p/android_add_custom_service_when_system_init.html

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