How to Get Root Permissions Through the Android Sdk

How can I get root permissions through the Android SDK?

What you need to do is something like:

Process root = Runtime.getRuntime().exec("su");

That causes SuperUser to show, which lets you either Allow or Block it from root access. This approach might not work if the user is not rooted. Here is a way you can test it.

Getting root permissions on android app within native code

The usual way in Linux of elevating privileges -- that is, to run an application with greater privileges than the logged-in user -- is to set the SUID flag on the executable (e.g., chmod ug+s ...). This will make the process take the identity of the binary's owner (usually root), rather than the logged-in user.

This is tricky to do effectively on Android, even on a rooted device. First, you won't be able to install an app using the usual (APK) mechanisms that includes binaries with SUID permissions. Second, an Android app is not an executable in the usual sense -- a single executable handles the launching of all apps.

Still, if you want to experiment on the command line, it should be possible to set the SUID flag on binaries, in at least some filesystem locations.

If you have a rooted Android, then very likely there is some infrastructure already in place to control privilege elevation. Most likely the "su" command will work (because there will be kernel mods to make it work), and it will be provided either with credentials or with some other way to control which apps can use it. I believe that, as you suggest, calling "su" is the usual way to do privilege elevation in apps on rooted Android. It is fraught with difficulties, however. There's a document https://su.chainfire.eu/ that explains how "su" is typically implemented in rooted Android devices, and gives some guidance on how to use it properly.

How to get access to / (root) directory using Storage Access framework

You can't get access to root folder if the device is not rooted.
See https://stackoverflow.com/a/5293771/4284706, https://stackoverflow.com/a/5436182/4284706 for answers if your device is rooted.

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