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Android framework 编程之 - Binder调用方UID

news 2025/8/1 0:39:29

注：不要弄混 uid 和 userID 的区别。

1. 获取Binder 调用方UID

	Binder.getCallingUid/*** Return the Linux UID assigned to the process that sent you the* current transaction that is being processed. This UID can be used with* higher-level system services to determine its identity and check* permissions. If the current thread is not currently executing an* incoming transaction, then its own UID is returned.*/@CriticalNative@android.ravenwood.annotation.RavenwoodReplacepublic static final native int getCallingUid();

2. 判断UID 是否是特殊UID

例如判断是否是System UID

uid == Process.SYSTEM_UID

特殊 UID 的列表
这里仅仅列出一部分
frameworks/base/core/java/android/os/Process.java

    /*** An invalid UID value.*/public static final int INVALID_UID = -1;/*** Defines the root UID.*/public static final int ROOT_UID = 0;/*** Defines the UID/GID under which system code runs.*/public static final int SYSTEM_UID = 1000;/*** Defines the UID/GID under which the telephony code runs.*/public static final int PHONE_UID = 1001;/*** Defines the UID/GID for the user shell.*/public static final int SHELL_UID = 2000;

将 Binder 调用方 UID 变为本地 UID ，豁免部分权限检查

	// 将调用标识变为本地进程，相对于System Server 就是 system server 进程final long token = Binder.clearCallingIdentity();try {// 权限检查的是本地进程。} finally {// 将调用标识变为非本地标识Binder.restoreCallingIdentity(token);}