Develop Reference

Grant permissions via voice input

Since Android 6 permissions can be requested on runtime. The user has the chance to grant or revoke permissions. He is always asked by the UI in form of a dialog popping up.
Is it somehow possible to grant permissions via voice input? I searched by myself but didn't find any approach for that. Is there any information to find about this topic? At least maybe some research how to make that possible maybe in future Android versions?
It would be great to find any kind of useful information about. that topic

I do not think so. It would not be safe, the user could accuse the application after capturing his audio without permission, for example.
You must EXPLICITLY allow anything (even acess the microphone to capture anything) that involves application access. So it's complicated for you to define something as explicit when using voice. The user may claim that he was only in a normal conversation when the application was granted permissions, and this can cause problems ...

Options for dealing with Android 6.0's new permissions requirements from a service or model component?

I'm looking into porting some existing code to take Android M's new way of dealing with permissions into consideration. However the permission API needs to have an activity associated with it (for example the requestPermissions() method's first parameter is an activity).
So how should a service that needs to check if a permissions has been granted and request for permissions use this new API if the service doesn't have an activity?
Is it possible for the service to create a dummy invisible activity just for use with the permissions API? (if its possible I don't like the thought of doing that anyway though).
Or suppose its not a service but a model class that needs to perform a permissions check, in MVC a model shouldn't have any knowledge of the Vs and Cs and yet now either it has to in order to know which Activity to use with the permission API. Or potentially lots of code might have to migrate from model code into Activity code.
Any thoughts on how to migrate non activity based code that needs to check/prompt for permissions over to Android 6.0?
Update: I left out an important piece of information - this is code that is pre-installed (our company provides code that device manufacture's place in rom) and often may be run at device boot time and run in the background. Therefore the usual situation of a user being prompted for permission when they launch the app or later (and there therefore being an activity at that point) does not necessarily apply.

So how should a service that needs to check if a permissions has been granted and request for permissions use this new API if the service doesn't have an activity?
There is almost always an activity, except for pre-installed apps and plugins for other apps. Otherwise, your service is unlikely to ever run, as nothing will have used an explicit Intent to start up one of your app's components, so it will remain in the stopped state.
For the ~99.9% of Android apps that have an activity already, if the permissions are needed for the whole operation of the app, request them on first run. As Snild Dolkow notes, if the user later revokes the permission through Settings, you can detect that without an activity, then use other UI options (e.g., Notification, app widget) to let the user know that operation is suspended until they grant you the permissions again, which they would then do through your activity.
Is it possible for the service to create a dummy invisible activity just for use with the permissions API?
Presumably you can have a Theme.NoDisplay activity use requestPermissions(). However, from the user's standpoint, it will not make much sense, unless there's some alternative UI (app widget?) that they are interacting with. Popping up a permission dialog out of nowhere is unlikely to make you popular.
UPDATE 2019-06-15: Note that Android Q bans services popping up activities frmo the background. Please use a notification instead.
in MVC a model shouldn't have any knowledge of the Vs and Cs and yet now either it has to in order to know which Activity to use with the permission API
Do not touch the models until you have requested the permission, and gracefully fail if the permission is revoked. You already have to gracefully fail in other circumstances (out of disk space, no Internet connection, etc.), so a revoked permission should be handled in much the same way.
using this new 6.0 API seems like an recipe for bad design and tight coupling
You are welcome to your opinion. Based on what I have read, the Android engineers believe that asking the user for permissions is part of the user experience and is best handled at the UI layer as a result.
Again: the vast majority of Android apps will not have a problem with this, as they have a user interface. Apps that do not have a user interface and need dangerous permissions are in for some amount of rework.
this is code that is pre-installed (our company provides code that device manufacture's place in rom) and often may be run at device boot time
First, please understand that this is so far from normal that you can't even see normal from where you are due to the curvature of the Earth. :-) You can't really complain that Google did not optimize this particular scenario.
As I understand it, even system apps should be asking for runtime permissions. The Camera app did, for example, on the 6.0 preview. That being said, there's gotta be some database on the device somewhere that is tracking what has been granted, and presumably there is some way to pre-populate it. However, the user could still revoke it from Settings, presumably. But, the manufacturer could pull some stunts (e.g., messing with the Settings app) to possibly even preclude that scenario. I'd be looking in the same area as "how do I get it so my app cannot be force-stopped?" that device manufacturers can do.
Your alternatives would be to get rid of the dangerous permissions or to migrate your app off the SDK and into a standard Linux binary that would be run as part of the boot process and be put into a Linux user group that has access to the stuff that you need.

Ask for it when the user enables whatever feature your service provides. They'll be in one of your activities at the time. Yes, it means that your activities need knowledge of what permissions your services will require.
The service can always check for the permission by itself, though, since checkSelfPermission() is available in all Context instances. So you don't need an activity for that.
I guess an alternative would be to have your service post a notification saying "feature X requires you to approve more permissions". Actually, that may be a good idea regardless, in case the user goes into settings and revokes any permissions after the fact. That notification would then take the user to some activity with an "enable feature X" button/checkbox -- ask for the permission when that is selected.

You can send a notification. Look this library to manage the permissions: permission library

How do I determine why my Android app requires certain permissions?

Let's say I have taken over development of an Android app, and my boss asks me why our app requires certain permissions to be displayed to users who buy the app on the Android Market.
Are there any tools or tricks I can use to determine what code triggers each permission, so I can figure out why our app functionally needs those permissions? In particular, I am interested in these permissions:
Phone Calls - Read phone status and identity
System Tools - Retrieve running applications - Allows app to retrieve information about currently and recently running tasks, May allow malicious apps to discover private information about other apps.
The app is a GPS tracking app, and it's not obvious why this permission might be needed.
It would also be helpful to get any tips on why this permission might be needed, even if you can't tell me how to directly analyze the code to find out.

Here is how I would track these down.
Step 1 - Find the manifest permissions declared in your AndroidManifest.xml
Basically everything inside the <uses-permission /> tags e.g.:
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
Step 2 - Search developer.android.com for classes that use these permissions
Let's take the case of READ_PHONE_STATE, the goal is to find which packages require this permission. A simple search on the dev portal for "READ_PHONE_STATE" starts our search, we are looking for classes here, in the top 5 search results I see the following classes:
TelephonyManager
PhoneStateListener
Click on the classes and get their package names:
android.telephony.TelephonyManager
android.telephony.PhoneStateListener
Step 3 Find classes in your project that import these packages
A simple grep will do, or a Ctrl-H in eclipse, File Search -> Containing text
Step 4 Comment out the import and see what breaks
These are likely candidates for why the permission is required. Confirm the methods in question by looking at the dev portal to validate that the permission is indeed required by that method.
Finally you should be able to tell your boss, READ_PHONE_STATE is required because we call function XYZ which gives us UVW.

Remove a permission and see where the app fails. The answer will be in the logcat output.
That's not an ideal solution though, since you might not know what you need to do in the app to trigger that permission.
I suspect "Read phone status and identity" means that the app is using the device IMEI or similar identifying information to uniquely identify the device to ensure that the app is only being run on a registered device. Or it might just be used as a sort of cookie to track the owner. Look for that code. And remove it, because that's the wrong way to do it. If you need to identify a specific android device, use ANDROID_ID from the Settings.Secure class. http://developer.android.com/reference/android/provider/Settings.Secure.html
As for "Retrieve running applications", I find that one somewhat suspicious. A very common way to implement GPS tracking is to launch a separate service in its own process. This way, if the app should crash, the service will keep going and can be re-attached. In this case, it's possible that the app is using the "Retrieve running applications" to identify and kill the service process. But if so, it's a clumsy way to do it.

With the latest build tools, you can run lint check which will highlight for you all the android SDK method calls which are requiring permissions.
See announcement here http://android-developers.blogspot.com/2015/07/get-your-hands-on-android-studio-13.html and documentation here https://developer.android.com/tools/debugging/annotations.html#permissions .
This is based on android annotations and after some adoption time 3rd party libraries can integrate permission annotations also

The answer for your boss is "because certain API features/calls/methods we use in our app require calee to hold certain permissions. It is for security reasons, and that's the way Android works". As for mentioned permissions - you have to check the code to see if these permissions are really required. Read phone status and identity may indicate your app try to get IMEI or something like this to uniquely identify device. Retrieve running applications - see no reason for GPS tracking app to hold this. But maybe you use 3rd party lib/code that uses this.

how are android security permissions checked at run-time?

This question has been asked before at How does Android enforce permissions?. While the discussions there are good, the question is still not fully answered.
In the development environment, exceptions are thrown when the app tries to do something that requires permissions not declared in AndroidManifest.xml. So how does the run-time system implement the run-time checking?
I guess it's most likely done in the core framework, which may or may not need support from native code. But I don't know what source code files in AOSP are relevant to this.

Android uses a lot of the standard Linux(-kernel?) mechanisms especially when it comes to hardware restrictions.
Every app gets assigned a new unique (Linux-)user id and whenever the app process is created the system creates it with that user id. The id will never change unless you remove the app. That means for accessing the lower system levels your app will appear as a certain user and every (Linux-)permission system that works with users will also apply to your app.
If you request WRITE_EXTERNAL_STORAGE in the manifest your app will also become member of the (Linux-)group (called sdcard_rw) that has permissions to write to that storage. Permissions on the filesystem are enforced to only allow writing to the system user (=owner) and the sdcard_rw group, anyone else (=other) may only read. See also Is Google blocking apps writing to SD cards
By doing that Android has to do pretty much nothing except for setting the correct UID/GIDs of the processes it spawns once the app starts and the rest is handled at lower levels. Apps that are not member of a certain group simply don't get access to certain hardware.
List of permission <> group mappings: platform.xml
There are also some (Android software) restrictions that are based on either the signature of your app and / or simply by looking up the permissions your app requested: e.g. ContextImpl#checkPermission() - but those permissions have to be checked at every entrypoint to code that allows restricted actions.
From time to time people discover ways to e.g. turn on GPS programmatically because a check like that is missing somewhere.

With regard to your second paragraph, "exceptions" are runtime faults. Permissions are not enforced at build time, only at run time.
Accessing hardware, low level operating system resources, and system files generally requires the app userid to be a member of an appropriate group which it may be assigned by the package manager as a result of having a corresponding android permission. (Familiar examples of that would be network sockets, and the sdcard write which zapl mentioned, but also system-only things like talking directly to the GSM modem or reading the raw touchscreen coordinates).
For the majority of android operations that are done by way of calling library functions which are stubs for interprocess communication to services running in a different process, the platform code running in the more privileged process on the receiving end of the ipc request checks with the package manager to find out if the calling application has the necessary android permission.
Many special permissions are only available to apps signed with the system signature - even if another app claims those in its manifest, they will not be applied by the package manager.

Internet access of an Android application -- but restricted to a single domain

I notice that (too) many applications on my Android phone require full internet access. In some cases, it seems like they just want to connect to some service. In other cases, it is clear they are phoning home. However, it seems like users have no easy way of checking which one is the case.
I realize that in the manifest permissions for Android there is a "android.permission.INTERNET", but is there a way to say "this application will only access some.domain.org", and maybe specify which protocols will be used, or something like that? Could the Android system enforce that somehow?

As far as I know, android.permission.INTERNET is the most specific you can get. I agree that it would be nice to be able to specify that my app only talked to an individual server, but in the end it wouldn't tell the user anything meaningful, since most protocols can be tunneled and proxied over most other ones with sufficient ingenuity.
The android UI devs decided to go with the broader permission rather than confusing regular users by displaying information that would not be functionally meaningful. As an alternative, you might consider including a note in either your application description or a popup immediately after installation that explains precisely how and why your application accesses the internet.
Edit:
You might be able to circumvent that permission altogether if you only wanted one-way messaging to the phone and did something excessively clever with C2DM. This would be a bad thing to do, however, and I haven't verified that it would actually work without that permission.