系统应用程序的 Android 运行时权限 [英] Android runtime permission for system apps

问题描述

关于 Android 运行时权限的问题.AFAIK，android 在运行时授予危险权限.我重置了我的手机，然后adb pull/data/system/users/0/runtime-permissions.xml，我发现android.ui.system已经授予了很多危险的权限.谁能告诉我它是怎么做的?

Question about Android runtime permissions. AFAIK, android grant dangerous permission at runtime. I reset my phone, then adb pull /data/system/users/0/runtime-permissions.xml, I found android.ui.system has already granted many dangerous permissions. can anybody tell me how it does?

推荐答案

插入机制 危险的运行时权限 通过用户确认对话框进入 /data/system/users/0/runtime-permissions.xml 文件仅适用于第三方应用程序，与此无关用于内置应用程序.

The mechanism to insert dangerous runtime permissions into the /data/system/users/0/runtime-permissions.xml file via a user-confirmed dialog applies only to third party applications, and is not relevant for built-in applications.

对于内置/系统应用程序和框架组件，所有默认情况下授予权限创建新用户或当设备启动并触发 systemReady 事件时.

For built-in/system applications and framework components, all permissions are granted by default when a new user is created or when the device boots and a systemReady event is fired.

您可以看到AndroidManifest.xml 来自 AOSP，其中为系统组件编写了所有类型的必需权限.

You can see the AndroidManifest.xml from AOSP, where all types of required permissions are written for system components.

对于第三方应用程序，当用户授予任何运行时权限时，它会被添加到文件 /data/system/users/0/runtime-permissions.xml 中.当用户从任何第三方应用程序中撤消该权限时，该权限将从文件中删除.在完全恢复出厂设置的情况下，所有第三方应用的运行时权限都会被删除，因为 /data/system/users/0/runtime-permissions.xml 被删除(数据分区擦除).

For third party apps, when the user grants any runtime permission, it gets added into the file /data/system/users/0/runtime-permissions.xml. The permission gets removed from the file when the user revokes it from any third party app. In the case of a full factory reset, runtime permissions of all third party apps are removed, as /data/system/users/0/runtime-permissions.xml gets deleted (data partition wipe).

但即使在恢复出厂设置后，/data/system/users/0/runtime-permissions.xml 包含系统应用程序的运行时权限(甚至是危险的)，请参阅默认权限:runtime-permissions.xml.

But even after a factory reset, /data/system/users/0/runtime-permissions.xml contains runtime permissions (even dangerous ones) for system apps, see the default permissions: runtime-permissions.xml.

这是因为:

所有默认权限都是从PackageManagerService，通过这两个方法:

All the default permissions are granted from PackageManagerService, via these two methods:

newUserCreated() //this get called when new user is created   
systemReady() //this get called when device is booted

和上面的方法内部调用:

and the above methods internally invoke:

DefaultPermissionPolicy.grantDefaultPermissions();

看看 DefaultPermissionPolicy 如何触发

如果你看到 DefaultPermissionPolicy 的实现，它包含加载所有类型权限的所有相关方法系统组件.

And if you see DefaultPermissionPolicy's implementation, it contains all the relevant method to load all type of permissions for System components.

特别是DefaultPermissionPolicy.grantDefaultPermissions()内部调用

grantPermissionsToSysComponentsAndPrivApps(userId);grantDefaultSystemHandlerPermissions(userId);

并且它在内部调用 grantRuntimePermissionsLPw()、其中执行所有剩余的工作.

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