Device Policy Manager - Reset Password - Android 3.0 Problems

问题

I am using Device Policy Manager in my Android App and I have a problem with Honeycomb devices. When attempting to call resetPassword I get an exception thrown. This is not the case in Froyo or Gingerbread, as both of those work fine.

The error is:

java.lang.RuntimeException: Unable to start receiver Package.Name.Test: java.lang.SecurityException: Permission Denial: writing com.android.providers.settings.SettingsProvider uri content://settings/secure from pid=x, uid=y requires android.permission.WRITE_SETTINGS

My Android Code is as follows:

DevicePolicyManager mDPM = (DevicePolicyManager) context.getSystemService(Context.DEVICE_POLICY_SERVICE);

if ((mDPM.getActiveAdmins() != null) && (mDPM.isAdminActive(new ComponentName(context, DeviceAdmin.class)))) {
    mDPM.resetPassword(extra, DevicePolicyManager.RESET_PASSWORD_REQUIRE_ENTRY);
    mDPM.lockNow();
} else {
    Log.d(TAG, "Could not lock because device admin not enabled");
}

The problem occurs at:

mDPM.resetPassword(extra, DevicePolicyManager.RESET_PASSWORD_REQUIRE_ENTRY);

My Device_Admin.xml is:

<device-admin xmlns:android="http://schemas.android.com/apk/res/android">
    <uses-policies>
        <force-lock />
        <wipe-data />
        <reset-password />
    </uses-policies>
</device-admin>

Like I said the device admin works great on Froyo and Gingerbread devices, although I do have some problems with users using different keyguards, an example is the Droid X and HTC Sense. This problem is with timing. When I call lockNow the device will turn off the screen but HTC Sense or MotoBlur will not actually lock the keyguard until the time that was set in Settings, Security, Lock Phone After.

Any help would be awesome! I just recently got a honeycomb tablet at I/O and haven't tested the app out on this device yet, but I see the errors on the market website with users with the Xoom running 3.0. Have not seen any 3.1 devices yet.

回答1:

I struggled with this also. The solution is also listed on one of your links, but I'll mention it here also in case it helps someone else.

If the device is brand new (or factory reset) the code fails as you describe.
If the user enters a password using the settings menu just once, somehow the same code starts working and keeps on working.

A very weird bug indeed!!

回答2:

On Android Honeycomb 3.0 platform, the DevicePolicyServiceManager is very different from Gingerbread, the whole flow of resetPassword() is:

DevicePolicyServiceManager.resetPassword() --> 
LockPatternUtils.checkPasswordInHistory() --> 
LockPatternUtils.passwordToHash() --> 
LockPatternUtils.getSalt() --> 
LockPatternUtils.putLong(SALT_KEY, salt) --> 
Settings.Secure.putLong(SALT_KEY, salt)

Here you should know why WRITE_SETTINGS is required, it seems that this is Google's mistake, they did not put the LockPatternUtils.checkPasswordInHistory() method in Binder.clearCallingIndentity() block.

One more thing, even if you add WRITE_SETTINGS permission in your AndroidManifest.xml file, it will tell you that WRTITE_SECURE_SETTINGS permission is also required.

Hope Google can fix this issue ASAP.

P.S. It seems that this issue has been fixed on ICS platform, Google has removed the checkPasswordInHistory() from resetPassword() block. I do not think this is a good solutoin and i don't know why? Maybe they wanna release ICS as soon as possible?

回答3:

I also faced this problem, what i can tell is if you didn't set the password manually even single time, the it will give force close asking for write_settings permission but if you try once by setting password manually from there on-wards it will work like charm.

回答4:

I was looking at this problem (which is readily reproducible on 3.1 as well, btw), but it appears that you already figured it out, based upon the issue you filed. I just wanted to note that here in case anyone else tried to research the answer.

来源：https://stackoverflow.com/questions/6085580/device-policy-manager-reset-password-android-3-0-problems

标签

android

android-3.0-honeycomb

device-admin