Permissions aren't only for requesting system functionality. You can also
restrict how other apps can interact with your app's components.

This guide explains how to check the set of permissions that another app has
declared. The guide also explains how you can configure activities, services,
content providers, and broadcast receivers to restrict how other apps can
interact with your app.
| **Note:** When restricting interactions to only apps provided by one developer, such as to secure interprocess communications, we recommend using custom signature permissions. For more info, see [Define a custom app permission](https://developer.android.com/guide/topics/permissions/defining).

## Check another app's permissions

To view the set of permissions that another app declares, use a device or
emulator to complete the following steps:

1. Open an app's **App info** screen.
2. Select **Permissions** . The **App permissions** screen loads.

   This screen shows a set of permission groups. The system organizes the set
   of permissions that an app has declared into these groups.

There are a number of other useful ways to check permissions:

- To check a permission during a call into a service, pass a permission string into [`Context.checkCallingPermission()`](https://developer.android.com/reference/android/content/Context#checkCallingPermission(java.lang.String)). This method returns an integer that indicates whether that permission has been granted to the current calling process. Note that this can only be used when you are executing a call coming in from another process, usually through an IDL interface published from a service or in some other way given to another process.
- To check whether another process has been granted a particular permission, pass the process ID (PID) into [`Context.checkPermission()`](https://developer.android.com/reference/android/content/Context#checkPermission(java.lang.String,%20int,%20int)).
- To check whether another package has been granted a particular permission, pass the package name into [`PackageManager.checkPermission()`](https://developer.android.com/reference/android/content/pm/PackageManager#checkPermission(java.lang.String,%20java.lang.String)).

## Restrict interactions with your app's activities

In the manifest, use the [`<activity>`](https://developer.android.com/guide/topics/manifest/activity-element) tag's `android:permission` attribute
to restrict which other apps can start that [`Activity`](https://developer.android.com/reference/android/app/Activity). The
permission is checked during [`Context.startActivity()`](https://developer.android.com/reference/android/content/Context#startActivity(android.content.Intent)) and
[`Activity.startActivityForResult()`](https://developer.android.com/reference/android/app/Activity#startActivityForResult(android.content.Intent,%20int)). If the caller doesn't have the
required permission, then a [`SecurityException`](https://developer.android.com/reference/java/lang/SecurityException) occurs.

## Restrict interactions with your app's services

In the manifest, use the [`<service>`](https://developer.android.com/guide/topics/manifest/service-element) tag's `android:permission` attribute
to restrict which other apps can start or bind to the associated
[`Service`](https://developer.android.com/reference/android/app/Service). The permission is checked during
[`Context.startService()`](https://developer.android.com/reference/android/content/Context#startService(android.content.Intent)), [`Context.stopService()`](https://developer.android.com/reference/android/content/Context#stopService(android.content.Intent)), and
[`Context.bindService()`](https://developer.android.com/reference/android/content/Context#bindService(android.content.Intent,%20android.content.ServiceConnection,%20int)). If the caller doesn't have the required
permission, then a `SecurityException` occurs.

## Restrict interactions with your app's content providers

In the manifest, use the [`<provider>`](https://developer.android.com/guide/topics/manifest/provider-element) tag's `android:permission` attribute
to restrict which other apps can access the data in a [`ContentProvider`](https://developer.android.com/reference/android/content/ContentProvider).
(Content providers have an important additional security facility available to
them called [URI permissions](https://developer.android.com/training/permissions/restrict-interactions#uri), which is described in the following section.)
Unlike for the other components, there are two separate permission attributes
you can set for content providers: [`android:readPermission`](https://developer.android.com/guide/topics/manifest/provider-element#rprmsn) restricts
which other apps can read from the provider, and [`android:writePermission`](https://developer.android.com/guide/topics/manifest/provider-element#wprmsn)
restricts which other apps can write to it. Note that if a provider is protected
with both a read and write permission, holding only the write permission doesn't
permit an app to read from a provider.

The permissions are checked when the provider is first retrieved and when an app
performs operations on the provider. If the requesting app doesn't have either
permission, a `SecurityException` occurs. Using [`ContentResolver.query()`](https://developer.android.com/reference/android/content/ContentResolver#query(android.net.Uri,%20java.lang.String%5B%5D,%20android.os.Bundle,%20android.os.CancellationSignal))
requires the read permission; using [`ContentResolver.insert()`](https://developer.android.com/reference/android/content/ContentResolver#insert(android.net.Uri,%20android.content.ContentValues)),
[`ContentResolver.update()`](https://developer.android.com/reference/android/content/ContentResolver#update(android.net.Uri,%20android.content.ContentValues,%20java.lang.String,%20java.lang.String%5B%5D)), or [`ContentResolver.delete()`](https://developer.android.com/reference/android/content/ContentResolver#delete(android.net.Uri,%20java.lang.String,%20java.lang.String%5B%5D)) requires
the write permission. In all of these cases, not holding the required permission
results in a `SecurityException`.

### Give access on a per-URI basis

The system provides you with additional fine-grained control over how other apps
can access your app's content providers. In particular, your content provider
can protect itself with read and write permissions while still allowing its
direct clients to share specific URIs with other apps. To declare your app's
support for this model, use the [`android:grantUriPermissions`](https://developer.android.com/guide/topics/manifest/provider-element#gprmsn) attribute or
the [`<grant-uri-permission>`](https://developer.android.com/guide/topics/manifest/grant-uri-permission-element) element.

You can also grant permissions on a per-URI basis. When starting an activity or
returning a result to an activity, set the
[`Intent.FLAG_GRANT_READ_URI_PERMISSION`](https://developer.android.com/reference/android/content/Intent#FLAG_GRANT_READ_URI_PERMISSION) intent flag, the
[`Intent.FLAG_GRANT_WRITE_URI_PERMISSION`](https://developer.android.com/reference/android/content/Intent#FLAG_GRANT_WRITE_URI_PERMISSION) intent flag, or both flags. This
gives other apps read, write, or read and write permissions, respectively, for
the data URI that's included in the intent. Other apps gain these permissions
for the specific URI regardless of whether they have permission to access data
in the content provider more generally.

For example, suppose that a user is using your app to view an email with an
image attachment. Other apps shouldn't be able to access the email contents in
general, but they might be interested in viewing the image. Your app can use an
intent and the `Intent.FLAG_GRANT_READ_URI_PERMISSION` intent flag to let an
image-viewing app see the image.

Another consideration is [app visibility](https://developer.android.com/training/package-visibility). If your app targets Android 11
(API level 30) or higher, the system makes some apps visible to your app
automatically and hides other apps by default. If your app has a content
provider and has granted URI permissions to another app, your app is
[automatically visible](https://developer.android.com/training/package-visibility/automatic) to that other app.

For more information, view the reference material for the
[`grantUriPermission()`](https://developer.android.com/reference/android/content/Context#grantUriPermission(java.lang.String,%20android.net.Uri,%20int)), [`revokeUriPermission()`](https://developer.android.com/reference/android/content/Context#revokeUriPermission(android.net.Uri,%20int)), and
[`checkUriPermission()`](https://developer.android.com/reference/android/content/Context#checkUriPermission(android.net.Uri,%20int,%20int,%20int)) methods.

## Restrict interactions with your app's broadcast receivers

Use the [`<receiver>`](https://developer.android.com/guide/topics/manifest/receiver-element) tag's `android:permission` attribute to
restrict which other apps can send broadcasts to the associated
[`BroadcastReceiver`](https://developer.android.com/reference/android/content/BroadcastReceiver). The system checks the permission *after*
[`Context.sendBroadcast()`](https://developer.android.com/reference/android/content/Context#sendBroadcast(android.content.Intent)) returns, as the system tries to deliver the
submitted broadcast to the given receiver. This means that a permission
failure doesn't result in an exception being thrown back to the caller---it just
doesn't deliver the [`Intent`](https://developer.android.com/reference/android/content/Intent).

You can also configure permissions programmatically:

- **To control which other apps can broadcast to a programmatically
  registered receiver:** Supply a permission to [`Context.registerReceiver()`](https://developer.android.com/reference/android/content/Context#registerReceiver(android.content.BroadcastReceiver,%20android.content.IntentFilter,%20java.lang.String,%20android.os.Handler)).
- **To restrict which broadcast receivers can receive a broadcast:** Supply a permission when calling [`Context.sendBroadcast()`](https://developer.android.com/reference/android/content/Context#sendBroadcast(android.content.Intent,%20java.lang.String)).

Note that both a receiver and a broadcaster can require a permission. When this
happens, both permission checks must pass for the intent to be delivered to
the associated target. For more information, see
[Restricting broadcasts with permissions](https://developer.android.com/guide/components/broadcasts#restrict-broadcasts-permissions).