【GTS-Fail】GtsSecurityHostTestCases#testNoExemptionsForSocketsBetweenCoreAndVendorBan

栏目: IT技术 · 发布时间: 4年前

内容简介:Gts-7.0-r4工具报出失败项GtsSecurityHostTestCasescom.google.android.security.gts.SELinuxHostTest#testNoExemptionsForSocketsBetweenCoreAndVendorBan

【GTS-Fail】GtsSecurityHostTestCases#testNoExemptionsForSocketsBetweenCoreAndVendorBan

【问题描述】

Gts-7.0-r4 工具 报出失败项

GtsSecurityHostTestCases

com.google.android.security.gts.SELinuxHostTest#testNoExemptionsForSocketsBetweenCoreAndVendorBan

<Failure message="junit.framework.AssertionFailedError: Policy exempts domains from ban on socket communications between core and vendor: [hal_audio_default]">
    <StackTrace>junit.framework.AssertionFailedError: Policy exempts domains from ban on socket communications between core and vendor: [hal_audio_default]
    at junit.framework.Assert.fail(Assert.java:57)
    at junit.framework.TestCase.fail(TestCase.java:227)
    at com.google.android.security.gts.SELinuxHostTest.testNoExemptionsForSocketsBetweenCoreAndVendorBan(SELinuxHostTest.java:221)

这里有个坑,报问题的时候说上个版本有,其实最终查证0004版本(2.20前)就有这个失败项了,当时芯片厂商也告知是waiver项了。。。

【问题结论】

是waiver项

失败项是由google的auto-patch代码导致,如果第一次遇到可以咨询aml是否waiver。

【分析详细】

测试逻辑总览

使用 linux 可执行程序:sepolicy-analyze,对机顶盒中的/sys/fs/selinux/policy文件进行解析,要求不能有返回值,命令是:

sepolicy-analyze policy attribute socket_between_core_and_vendor_violators

即:不允许有type(类型)与该attribute(属性)“socket_between_core_and_vendor_violators”有关联,字面意思:core与vendor的违规socket特权

system/sepolicy/tools/sepolicy-analyze/README

ATTRIBUTE (attribute)

sepolicy-analyze out/target/product/ /root/sepolicy attribute Displays the types associated with the specified attribute name.

该权限详细限制在以下代码中有论述,Android TREBLE架构解耦计划相关

system/sepolicy/prebuilts/api/26.0/public/domain.te

system/sepolicy/prebuilts/api/27.0/public/domain.te

system/sepolicy/prebuilts/api/28.0/public/domain.te:

system/sepolicy/public/domain.te

# On full TREBLE devices, socket communications between core components and vendor components are
# not permitted.
full_treble_only(`
  # Most general rules first, more specific rules below.

  # Core domains are not permitted to initiate communications to vendor domain sockets.
  # We are not restricting the use of already established sockets because it is fine for a process
  # to obtain an already established socket via some public/official/stable API and then exchange
  # data with its peer over that socket. The wire format in this scenario is dicatated by the API
  # and thus does not break the core-vendor separation.

梳理测试项逻辑

反编译后定位测试项

./com/google/android/security/gts/SELinuxHostTest.java

public void testNoExemptionsForVendorExecutingCore() throws Exception {
        if (isFullTrebleDevice()) {
            Set<String> types = sepolicyAnalyzeGetTypesAssociatedWithAttribute("vendor_executes_system_violators");//该语句是测试判断,返回测试结果  
            if (!types.isEmpty()) {
                List<String> sortedTypes = new ArrayList(types);
                Collections.sort(sortedTypes);
                fail("Policy exempts vendor domains from ban on executing files in /system: " + sortedTypes);//此处assert,原因是容器types有东西,东西就是‘[hal_audio_default]’  
            }
        }
    }

看一下方法的测试逻辑:sepolicyAnalyzeGetTypesAssociatedWithAttribute()

通过ProcessBuilder开启一个进程,用于执行linux命令:sepolicy-analyze policy attribute socket_between_core_and_vendor_violators

然后获取这个命令的标准输出进行结果判断

private Set<String> sepolicyAnalyzeGetTypesAssociatedWithAttribute(String attribute) throws Exception {
        BufferedReader in;
        Throwable th;
        Throwable th2;
        Set<String> types = new HashSet();
        //通过ProcessBuilder开启一个进程,用于执行linux命令:sepolicy-analyze policy attribute socket_between_core_and_vendor_violators  
        ProcessBuilder pb = new ProcessBuilder(new String[]{this.mSepolicyAnalyze.getAbsolutePath(), this.mDevicePolicyFile.getAbsolutePath(), "attribute", attribute});
......
            in = new BufferedReader(new InputStreamReader(p.getInputStream()));
            th = null;
            while (true) {
                try {
                    String type = in.readLine();
                    if (type != null) {
                        types.add(type.trim());//获取有效标准输出,写到结果容器中存储  
                    }}} 
......
        return types;
......
    }

现在基本逻辑就清楚了,只要这个命令执行有结果返回就是不被允许的,现在需要分析这个工具‘sepolicy-analyze’是干嘛的?

在Android工程源码中搜索,我们找到了这个host可执行程序的源码

system/sepolicy/tools/sepolicy-analyze/

结合网络资料以及阅读源码和README文档,澄清测试的命令用途:解析policy文件返回与attribute相关联的type值

system/sepolicy/tools/sepolicy-analyze/README

63 ATTRIBUTE (attribute)

64 sepolicy-analyze out/target/product/ /root/sepolicy attribute

65

66 Displays the types associated with the specified attribute name.

工程中搜索确认

搜过确认一下到底在哪里使得他们关联的,定位到一下te文件

./system/sepolicy/vendor/hal_audio_default.te:1
type hal_audio_default, domain, socket_between_core_and_vendor_violators;

查证git log,我们发现是如下的commit导致的,是google的auto-path

commit 783f5b52195f0168f4c9db29b5a80ac63fb04020
Author: xxxxxx
Date:   Mon Feb 17 11:33:16 2020 +0800

    auto patch added:CecAudio

diff --git a/vendor/hal_audio_default.te b/vendor/hal_audio_default.te
index 0dc2170..9da0f1b 100644
--- a/vendor/hal_audio_default.te
+++ b/vendor/hal_audio_default.te
@@ -1,4 +1,4 @@
-type hal_audio_default, domain;
+type hal_audio_default, domain, socket_between_core_and_vendor_violators; #此处添加的关联,问题找到了根源  
 hal_server_domain(hal_audio_default, hal_audio)

到此,问题很大概率可确认为Google-waiver,因为引入问题的代码是Google的。接下来需向芯片厂商或Google沟通确认

由于报问题的乌龙,事实是该问题很久之前已澄清过,所以这一通分析并木有什么卵用。。。。。。


以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持 码农网

查看所有标签

猜你喜欢:

本站部分资源来源于网络,本站转载出于传递更多信息之目的,版权归原作者或者来源机构所有,如转载稿涉及版权问题,请联系我们

Web 2.0 Heroes

Web 2.0 Heroes

Bradley L. Jones / Wiley / 2008-04-14 / USD 24.99

Web 2.0 may be an elusive concept, but one thing is certain: using the Web as merely a means of retrieving and displaying information is history. Today?s Web is immediate, interactive, innovative. It ......一起来看看 《Web 2.0 Heroes》 这本书的介绍吧!

CSS 压缩/解压工具
CSS 压缩/解压工具

在线压缩/解压 CSS 代码

Base64 编码/解码
Base64 编码/解码

Base64 编码/解码

HEX CMYK 转换工具
HEX CMYK 转换工具

HEX CMYK 互转工具