application-dev/security/accesstoken-guidelines.md

# Applying for Permissions

## When to Use

Application permissions are used to prevent unauthorized access to sensitive data or critical functions. The [Ability Privilege Level (APL)](accesstoken-overview.md#application-apls) of an application can be normal (default), system_basic, or system_core. The [permission types](accesstoken-overview.md#permission-types) include system_grant and user_grant. For details about the application permissions, see the [Application Permission List](permission-list.md).

This document describes the following operations:

- [Declaring Permissions in the Configuration File](#declaring-permissions-in-the-configuration-file)
- [Declaring the ACL](#declaring-the-acl)
- [Requesting User Authorization](#requesting-user-authorization)
- [Pre-authorizing user_grant Permissions](#pre-authorizing-user_grant-permissions)

## Declaring Permissions in the Configuration File

The permissions required by an application must be declared one by one in the configuration file of the project. Otherwise, the application cannot obtain the permissions.

> **NOTE**
>
> If an application of the normal APL requires a permission of the system_basic or system_core level, you must also declare the permission in the [ACL](#declaring-the-acl).

The following table describes the fields in the configuration file.

| Field     | Mandatory| Description                                                        |
| --------- | -------- | ------------------------------------------------------------ |
| name      | Yes      | Name of the permission.                                                  |
| reason    | No      | Reason for applying for the permission. For details, see [Specifications for reason](#specifications-for-reason).<br>This parameter is mandatory when a user_grant permission is required.|
| usedScene | No      | Application scenario of the permission.<br>This parameter is mandatory when a user_grant permission is required.|
| abilities | No      | Abilities that require the permission. The value is an array.<br>**Applicable model**: stage|
| ability   | No      | Abilities that require the permission. The value is an array.<br>**Applicable model**: FA|
| when      | No      | Time when the permission is required. <br>Value:<br>- **inuse**: The permission is required only when the application is in use.<br>- **always**: The permission is required no matter whether the application is in use.|

### Stage Model

If your application is developed based on the stage model, declare the required permissions in [**module.json5**](../quick-start/module-configuration-file.md).

```json
{
  "module" : {
    // ...
    "requestPermissions":[
      {
        "name" : "ohos.permission.PERMISSION1",
        "reason": "$string:reason",
        "usedScene": {
          "abilities": [
            "FormAbility"
          ],
          "when":"inuse"
        }
      },
      {
        "name" : "ohos.permission.PERMISSION2",
        "reason": "$string:reason",
        "usedScene": {
          "abilities": [
            "FormAbility"
          ],
          "when":"always"
        }
      }
    ]
  }
}
```

### FA Model

If your application is developed based on the FA model, declare the required permissions in **config.json**.

```json
{
  "module" : {
    // ...
    "reqPermissions":[
      {
        "name" : "ohos.permission.PERMISSION1",
        "reason": "$string:reason",
        "usedScene": {
          "ability": [
            "FormAbility"
          ],
          "when":"inuse"
        }
      },
      {
        "name" : "ohos.permission.PERMISSION2",
        "reason": "$string:reason",
        "usedScene": {
          "ability": [
            "FormAbility"
          ],
          "when":"always"
        }
      }
    ]
  }
}
```

### Specifications for reason

The **reason** field (reason for applying for the permission) is mandatory when a user_grant permission is required. You need to configure each permission required by your application in the application configuration file.

When the user_grant permissions are authorized by the user in a dialog box, the [permission group](accesstoken-overview.md#permission group and sub-permissions) is displayed. For details about the permission groups, see [Application Permission List](permission-group-list.md).

The **reason** field must comply with the following specifications:

1. The reason must be clear and concise without redundant separators.

   **Recommended sentence pattern**: Used for something/Used to do something/Used for doing something.

   **Example**: Used for code scanning and photographing.

2. To ensure optimal user experience, the recommended length of **reason** is fewer than 72 characters (36 Chinese characters displayed in two lines on the UI) and the maximum length is 256 characters.

3. If **reason** is not set, the default reason will be used.

The reason for using a permission is presented in the permission authorization window and **Settings**. The path for **Settings** is **Settings** > **Privacy** > **Permission manager** > Permission details of an app.

1. If permissions in the **Phone**, **Messaging**, **Calendar**, **Contacts**, and **Call logs** permission groups are required, the content and usage of the permissions must be presented to the user.

   **Sentence pattern**: Permissions A and B, used to ...

   **Example**: Permission A and permission B, used to obtain the call status and mobile network information and for secure operation and statistics charging services.

2. If permissions in other permission groups are required, the reason for using the first permission requested in the permission group is presented to the user. The permissions are listed in the same sequence as they are sorted in permission groups of **Permission manager**.

   **Example**: If Permission group A = {permission A, permission B, permission C} and {permission C, permission B} are requested, the reason for using permission B is presented to the user.

## Declaring the ACL

If an application of the normal APL requires permissions of the system_basic or system_core level, you must also declare the required permissions in the ACL.

For example, if an application needs to access audio clips of a user and capture screenshots, it requires the ohos.permission.WRITE_AUDIO permission (of the system_basic level) and the ohos.permission.CAPTURE_SCREEN permission (of the system_core level). In this case, you need to add the required permissions to the **acls** field in the [HarmonyAppProvision configuration file](app-provision-structure.md).

```json
{
	// ...
	"acls":{
		"allowed-acls":[
			"ohos.permission.WRITE_AUDIO",
      "ohos.permission.CAPTURE_SCREEN"
		]
	}
}
```

## Requesting User Authorization

User authorization is required when an application needs to access user privacy information (such as Location or Calendar information) or using system abilities (such as the camera ability to take photos or record videos). In this case, the application requires a user_grant permission. Before the application accesses the data or using the system ability, a verification is performed to check whether the user has granted the permission to the application. If the user has not granted the permission, a dialog box will be displayed to request user authorization. The following figure shows an example.

**Figure 1** Requesting user authorization

![](figures/permission-read_calendar.png)

> **NOTE**
>
> Each time before an API protected by a user_grant permission is called, **[requestPermissionsFromUser()](../reference/apis/js-apis-abilityAccessCtrl.md#requestpermissionsfromuser9)** will be called to request user authorization. After the permission is granted, the user may revoke the authorization in **Settings**. Therefore, the previous authorization status cannot be persistent.

### Stage Model

Example: Apply for the permission for an application to access the Calendar.

1. Declare the **ohos.permission.READ_CALENDAR** permission in the configuration file. For details, see [Declaring Permissions in the Configuration File](#declaring-permissions-in-the-configuration-file).

2. Check whether the user has granted the permission.

   Use [checkAccessToken()](../reference/apis/js-apis-abilityAccessCtrl.md#checkaccesstoken9) to check whether the user has granted the permission. If yes, the application can access the Calendar. Otherwise, user authorization is required.

   ```typescript
   import bundleManager from '@ohos.bundle.bundleManager';
   import abilityAccessCtrl, { Permissions } from '@ohos.abilityAccessCtrl';
   import { BusinessError } from '@ohos.base';

   async function checkAccessToken(permission: Permissions): Promise<abilityAccessCtrl.GrantStatus> {
     let atManager: abilityAccessCtrl.AtManager = abilityAccessCtrl.createAtManager();
     let grantStatus: abilityAccessCtrl.GrantStatus = abilityAccessCtrl.GrantStatus.PERMISSION_DENIED;

     // Obtain the access token ID of the application.
     let tokenId: number = 0;
     try {
       let bundleInfo: bundleManager.BundleInfo = await bundleManager.getBundleInfoForSelf(bundleManager.BundleFlag.GET_BUNDLE_INFO_WITH_APPLICATION);
       let appInfo: bundleManager.ApplicationInfo = bundleInfo.appInfo;
       tokenId = appInfo.accessTokenId;
     } catch (error) {
       let err: BusinessError = error as BusinessError;
       console.error(`Failed to get bundle info for self. Code is ${err.code}, message is ${err.message}`);
     }

     // Check whether the user has granted the permission.
     try {
       grantStatus = await atManager.checkAccessToken(tokenId, permission);
     } catch (error) {
       let err: BusinessError = error as BusinessError;
       console.error(`Failed to check access token. Code is ${err.code}, message is ${err.message}`);
     }

     return grantStatus;
   }

   async function checkPermissions(): Promise<void> {
     const permissions: Array<Permissions> = ['ohos.permission.READ_CALENDAR'];
     let grantStatus: abilityAccessCtrl.GrantStatus = await checkAccessToken(permissions[0]);

     if (grantStatus === abilityAccessCtrl.GrantStatus.PERMISSION_GRANTED) {
       // If the user has granted the permission, the application can access the Calendar.
     } else {
       // Apply for the permission to access the Calendar.
     }
   }
   ```

3. Request user authorization dynamically.

   Use [requestPermissionsFromUser()](../reference/apis/js-apis-abilityAccessCtrl.md#requestpermissionsfromuser9) to apply for permissions from the user when the application is running. A list of permissions, such as the permissions to access the Location, Calendar, camera, and microphone, can be passed in. The user can grant or deny the permissions.

   You can have [**requestPermissionsFromUser()**](../reference/apis/js-apis-abilityAccessCtrl.md#requestpermissionsfromuser9) called in **onWindowStageCreate()** of the UIAbility to dynamically request user authorization, or request user authorization on the UI based on service requirements.

   Sample code for requesting user authorization using UIAbility:

   ```typescript
   import UIAbility from '@ohos.app.ability.UIAbility';
   import window from '@ohos.window';
   import abilityAccessCtrl, { Context, PermissionRequestResult, Permissions } from '@ohos.abilityAccessCtrl';
   import { BusinessError } from '@ohos.base';

   const permissions: Array<Permissions> = ['ohos.permission.READ_CALENDAR'];
   export default class EntryAbility extends UIAbility {
    // ...
    onWindowStageCreate(windowStage: window.WindowStage) {
      // Main window is created. Set the main page for this ability.
      let context: Context = this.context;
      let atManager: abilityAccessCtrl.AtManager = abilityAccessCtrl.createAtManager();
      // The return value of requestPermissionsFromUser determines whether to display a dialog box to request user authorization.

      atManager.requestPermissionsFromUser(context, permissions).then((data: PermissionRequestResult) => {
        let grantStatus: Array<number> = data.authResults;
        let length: number = grantStatus.length;
        for (let i = 0; i < length; i++) {
          if (grantStatus[i] === 0) {
            // If the user has granted the permission, the application can access the Calendar.
          } else {
            // If the user has not granted the permission, display a message indicating that user authorization is required, and direct the user to the Settings page to set the permission.
            return;
          }
        }
        // The authorization is successful.
      }).catch((err: BusinessError) => {
        console.error(`Failed to request permissions from user. Code is ${err.code}, message is ${err.message}`);
      })
      // ...
    }
   }
   ```

   Sample code for requesting user authorization on the UI:

   ```typescript
   import abilityAccessCtrl, { Context, PermissionRequestResult, Permissions } from '@ohos.abilityAccessCtrl';
   import { BusinessError } from '@ohos.base';

   const permissions: Array<Permissions> = ['ohos.permission.READ_CALENDAR'];

   @Entry
   @Component
   struct Index {
    reqPermissionsFromUser(permissions: Array<Permissions>): void {
      let context: Context  = getContext(this) as common.UIAbilityContext;
      let atManager: abilityAccessCtrl.AtManager = abilityAccessCtrl.createAtManager();
      // The return value of requestPermissionsFromUser determines whether to display a dialog box to request user authorization.
      atManager.requestPermissionsFromUser(context, permissions).then((data: PermissionRequestResult) => {
        let grantStatus: Array<number> = data.authResults;
        let length: number = grantStatus.length;
        for (let i = 0; i < length; i++) {
          if (grantStatus[i] === 0) {
            // If the user has granted the permission, the application can access the Calendar.
          } else {
            // If the user has not granted the permission, display a message indicating that user authorization is required, and direct the user to the Settings page to set the permission.
            return;
          }
        }
        // The authorization is successful.
      }).catch((err: BusinessError) => {
        console.error(`Failed to request permissions from user. Code is ${err.code}, message is ${err.message}`);
      })
    }

    // Page display.
    build() {
      // ...
    }
   }
   ```

4. Perform subsequent operations based on the authorization result.

   After [requestPermissionsFromUser()](../reference/apis/js-apis-abilityAccessCtrl.md#requestpermissionsfromuser9) is called, the application waits for the user authorization result. If the user has granted the permission, the application can access the Calendar. If the user has not granted the permission, a message will be displayed indicating that user authorization is required, and the user is directed to **Settings** to set the permission.

   The ArkTS syntax does not support direct use of **globalThis**. A singleton map is required to enable the use of **globalThis**. You need to perform the following operations:

   a. Import the created singleton object **GlobalThis** to **EntryAbility.ets**.
      ```typescript
       import {GlobalThis} from '../utils/globalThis'; // Set based on the path of globalThis.ets.
      ```
   b. Add the following to **onCreate**:
      ```typescript
       GlobalThis.getInstance().setContext('context', this.context);
      ```

   > **NOTE**
   >
   > An alert will be generated when a **.ets** file is imported to a TS file. To prevent the alert, you need to change the file name extension of **EntryAbility.ts** to **EntryAbility.ets** and modify the file name extension in **module.json5**.

   The sample code of **globalThis.ets** is as follows:
   ```typescript
   import { Context } from '@ohos.abilityAccessCtrl';

   // Construct a singleton object.
   export class GlobalThis {
     private constructor() {}
     private static instance: GlobalThis;
     private _uiContexts = new Map<string, Context>();

     public static getInstance(): GlobalThis {
       if (!GlobalThis.instance) {
         GlobalThis.instance = new GlobalThis();
       }
       return GlobalThis.instance;
     }

     getContext(key: string): Context | undefined {
       return this._uiContexts.get(key);
     }

     setContext(key: string, value: Context): void {
       this._uiContexts.set(key, value);
     }

     // Set other content to be passed in the same way.
   }
   ```

   ```typescript
   import { Context } from '@ohos.abilityAccessCtrl';
   import { BusinessError } from '@ohos.base';
   import Want from '@ohos.app.ability.Want';
   import { GlobalThis } from '../utils/globalThis';
   import common from '@ohos.app.ability.common';

   function openPermissionsInSystemSettings(): void {
    let context: common.UIAbilityContext = GlobalThis.getInstance().getContext('context');
    let wantInfo: Want = {
      action: 'action.settings.app.info',
      parameters: {
        settingsParamBundleName: 'com.example.myapplication' // Open the Details page of the application.
      }
    }
    context.startAbility(wantInfo).then(() => {
      // ...
    }).catch((err: BusinessError) => {
      // ...
    })
   }
   ```

### FA Model

Call [requestPermissionsFromUser()](../reference/apis/js-apis-inner-app-context.md#contextrequestpermissionsfromuser7) to request user authorization.

```ts
import { BusinessError } from '@ohos.base';
import featureAbility from '@ohos.ability.featureAbility';

reqPermissions() {
    let context = featureAbility.getContext();
    let array:Array<string> = ["ohos.permission.PERMISSION2"];
    // The return value of requestPermissionsFromUser determines whether to display a dialog box to request user authorization.
    context.requestPermissionsFromUser(array, 1).then(data => {
        console.log("data:" + JSON.stringify(data));
        console.log("data permissions:" + JSON.stringify(data.permissions));
        console.log("data result:" + JSON.stringify(data.authResults));
    }, (err: BusinessError) => {
        console.error('Failed to start ability', err.code);
    });
}
```

## Pre-authorizing user_grant Permissions

The user_grant permissions can be pre-authorized in the [**install_list_permission.json** file](https://gitee.com/openharmony/vendor_hihope/blob/master/rk3568/preinstall-config/install_list_permissions.json) in the **/system/etc/app/** directory of the device. When the device starts, it loads the **install_list_permission.json** file. When the applications are installed, the user_grant permissions are authorized.

The **install_list_permissions.json** file contains the following fields:

- **bundleName**: bundle name of the application.
- **app_signature**: fingerprint information of the application. For details, see **Configuration in install_list_capability.json** in the [Application Privilege Configuration Guide](../../device-dev/subsystems/subsys-app-privilege-config-guide.md).
- **permissions**: The **name** field specifies the name of the user_grant permission to pre-authorize. The **userCancellable** field specifies whether the user can revoke the pre-authorization. The value **true** means the user can revoke the pre-authorization; the value **false** means the opposite.

```json
[
  // ...
  {
    "bundleName": "com.example.myapplication", // Bundle name.
    "app_signature": ["****"], // Fingerprint information.
    "permissions":[
      {
        "name": "ohos.permission.PERMISSION_X", // Permission to pre-authorize.
        "userCancellable": false // The user cannot revoke the authorization.
      },
      {
        "name": "ohos.permission.PERMISSION_X", // Permission to pre-authorize.
        "userCancellable": true // The user can revoke the authorization.
      }
    ]
  }
]
```