android 检测过程,Android 系统对permision的检测过程
Android 系統對permision的檢測過程
RK3288 5.1 中以太網設置靜態IP 對permission的檢測
簡略的調用過程如下：
frameworks\opt\net\ethernet\java\com\android\server\ethernet\EthernetServiceImpl.java
public void setConfiguration(IpConfiguration config) {
if (!mStarted.get()) {
Log.w(TAG, "System isn't ready enough to change ethernet configuration");
}
enforceChangePermission();
enforceConnectivityInternalPermission();
synchronized (mIpConfiguration) {
mEthernetConfigStore.writeIpAndProxyConfigurations(config);
// TODO: this does not check proxy settings, gateways, etc.
// Fix this by making IpConfiguration a complete representation of static configuration.
if (!config.equals(mIpConfiguration)) {
mIpConfiguration = new IpConfiguration(config);
mTracker.stop();
mTracker.start(mContext, mHandler);
}
}
}
private void enforceConnectivityInternalPermission() {
mContext.enforceCallingOrSelfPermission(
android.Manifest.permission.CONNECTIVITY_INTERNAL,
"ConnectivityService");
}
frameworks\base\core\java\android\app\ContextImpl.java
public void enforceCallingOrSelfPermission(
String permission, String message) {
enforce(permission,
checkCallingOrSelfPermission(permission),
true,
Binder.getCallingUid(),
message);
通過Binder這個類，可以獲得調用服務的應用的ID，通過這個ID，可以獲得應用的相關信息；
@Override
public int checkCallingOrSelfPermission(String permission) {
if (permission == null) {
throw new IllegalArgumentException("permission is null");
}
return checkPermission(permission, Binder.getCallingPid(),
Binder.getCallingUid());
}
@Override
public int checkPermission(String permission, int pid, int uid) {
if (permission == null) {
throw new IllegalArgumentException("permission is null");
}
try {
return ActivityManagerNative.getDefault().checkPermission(
permission, pid, uid);
} catch (RemoteException e) {
return PackageManager.PERMISSION_DENIED;
}
}
frameworks\base\services\core\java\com\android\server\ActivityManagerService.java
@Override
public int checkPermission(String permission, int pid, int uid) {
if (permission == null) {
return PackageManager.PERMISSION_DENIED;
}
return checkComponentPermission(permission, pid, UserHandle.getAppId(uid), -1, true);
}
int checkComponentPermission(String permission, int pid, int uid,
int owningUid, boolean exported) {
if (pid == MY_PID) {
return PackageManager.PERMISSION_GRANTED;
}
return ActivityManager.checkComponentPermission(permission, uid,
owningUid, exported);
}
frameworks\base\core\java\android\app\ActivityManager.java
/** @hide */
public static int checkComponentPermission(String permission, int uid,
int owningUid, boolean exported) {
// Root, system server get to do everything.
if (uid == 0 || uid == Process.SYSTEM_UID) {
return PackageManager.PERMISSION_GRANTED;
}
// Isolated processes don't get any permissions.
if (UserHandle.isIsolated(uid)) {
return PackageManager.PERMISSION_DENIED;
}
// If there is a uid that owns whatever is being accessed, it has
// blanket access to it regardless of the permissions it requires.
if (owningUid >= 0 && UserHandle.isSameApp(uid, owningUid)) {
return PackageManager.PERMISSION_GRANTED;
}
// If the target is not exported, then nobody else can get to it.
if (!exported) {
/*
RuntimeException here = new RuntimeException("here");
here.fillInStackTrace();
Slog.w(TAG, "Permission denied: checkComponentPermission() owningUid=" + owningUid,
here);
*/
return PackageManager.PERMISSION_DENIED;
}
if (permission == null) {
return PackageManager.PERMISSION_GRANTED;
}
try {
return AppGlobals.getPackageManager()
.checkUidPermission(permission, uid);
} catch (RemoteException e) {
// Should never happen, but if it does... deny!
Slog.e(TAG, "PackageManager is dead?!?", e);
}
return PackageManager.PERMISSION_DENIED;
}
對于普通應用將通過PackageManagerService中保持的信息進行判斷是否具有相應的權限；
base/services/core/java/com/android/server/pm/PackageManagerService.java
@Override
public int checkUidPermission(String permName, int uid) {
synchronized (mPackages) {
Object obj = mSettings.getUserIdLPr(UserHandle.getAppId(uid));
if (obj != null) {
GrantedPermissions gp = (GrantedPermissions)obj;
if (gp.grantedPermissions.contains(permName)) {
return PackageManager.PERMISSION_GRANTED;
}
} else {
ArraySet perms = mSystemPermissions.get(uid);
if (perms != null && perms.contains(permName)) {
return PackageManager.PERMISSION_GRANTED;
}
}
}
return PackageManager.PERMISSION_DENIED;
}
每次開機系統PackageManagerService都會還原現有app的安裝信息，這些信息被放在/data/system/packages.xml里，由mSettings管理。另外/data/system/packages.list記錄了app的uid和數據路徑等信息。
總結
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