Permissions. Lecture 18

Transcription

1 Permissions Lecture 18

2 Topics related Android permissions Defining & using applica:on permissions Component permissions

3 Permissions Android protects resources & data with permissions Example: who has the access to use the database in the app Used to limit access to User informa:on: Contacts Cost- sensi:ve API s: SMS/MMS System resources: Camera

4 Permissions Permissions are represented as strings In AndroidManifest.xml apps declare the permissons They use themselves They require of other components

5 Using permissions Applica:ons specify permissions they use through a <uses- permission> tag User must accept these permissions before an applica:on can be installed

6 Using permissions <manifest > <uses- permission android:name="android.permission.internet" /> <uses- permission android:name="android.permission.camera" /> <uses- permission android:name="android.permission.access_fine_ LOCATION" /> </manifest> - - hqps://developer.android.com/reference/ android/manifest.permission.html

7 Example Select a contact from contacts database Display a map centered on selected contact s address Contact list is private informa:on In Manifest file <uses- permission android:name="android.permission.read_conta CTS" />

8 Ques:on 1 Which of the following describe situa:ons where permissions might be used? a. To restrict access to costly opera:ons b. To restrict access to device hardware features c. To restrict access to user data d. To restrict applica:on loading to devices that run a specific version of Android

9 Defining permission Apps can also define and enforce their own permissions If your applica:on performs a privileged/ dangerous opera:on You might not want to allow just any applica:on to invoke yours So you can define & enforce your own permission

10 Example In manifest file <permission android: name= PackageName.MYA_PERM android:label= string/mya_permission_label_string > </permission>

11 AndroidManifest.xml <applica:on android:allowbackup="true" android:permission= PackageName. MYA_PERM >.. </applica:on>

12 Using the new permission Apps that want to use the previous app must now acquire the correct permission In manifest <uses- permission android:name= PackageName. MYA_PERM" /> Otherwise Android throw SecurityExcep:on:Permission Denial:

13 Ques:on 2 Which XML tag or aqribute is used to specify an applica:on- specific permission that an applica:on requires of any other applica:on that wants to interact with it? a) android:permission b) <permission> c) <uses- permission> d) <define- permission>

14 Component Permissions Individual components can set their own permissions, restric:ng which other components can access them Component permissions take precedence over applica:on- level permissions

15 Ac:vity Permissions Restricts which components can start the associated ac:vity Checked within execu:on of startac:vity() startac:vityforresult() Throws SecurityExcep:on on permission failure

16 Service Permissions Restricts which components can start or bind to the associated service Checked within execu:on of Context.startService() Context.stopService() Context.bindService() Throws SecurityExcep:on on permission failure

17 BroadcastReceiver Permissions Restricts which components can send & receive broadcasts Permissions checked in mul:ple places

18 ContentProvider Permissions Restrict which components can read & write the data in a ContentProvider

19 Ques:on 3 Which Excep:on is thrown if one Ac:vity tries to start another Ac:vity for which it does not have the appropriate permissions? See: hqp://developer.android.com/guide/topics/ security/permissions.html for more informa:on a) AccessControlExcep:on b) SecurityExcep:on c) NullPointerExcep:on d) ClassCastExcep:on