Merge "Permission fix: don't require BACKUP perm for self-restores"

4 files changed, 75 insertions, 23 deletions

diff --git a/cmds/bmgr/src/com/android/commands/bmgr/Bmgr.java b/cmds/bmgr/src/com/android/commands/bmgr/Bmgr.java
index b5fddfa..ac0e410 100644
--- a/cmds/bmgr/src/com/android/commands/bmgr/Bmgr.java
+++ b/cmds/bmgr/src/com/android/commands/bmgr/Bmgr.java
@@ -217,8 +217,7 @@ public final class Bmgr {
 
         // The rest of the 'list' options work with a restore session on the current transport
         try {
-            String curTransport = mBmgr.getCurrentTransport();
-            mRestore = mBmgr.beginRestoreSession(curTransport);
+            mRestore = mBmgr.beginRestoreSession(null, null);
             if (mRestore == null) {
                 System.err.println(BMGR_NOT_RUNNING_ERR);
                 return;
@@ -349,8 +348,7 @@ public final class Bmgr {
 
     private void doRestorePackage(String pkg) {
         try {
-            String curTransport = mBmgr.getCurrentTransport();
-            mRestore = mBmgr.beginRestoreSession(curTransport);
+            mRestore = mBmgr.beginRestoreSession(pkg, null);
             if (mRestore == null) {
                 System.err.println(BMGR_NOT_RUNNING_ERR);
                 return;
@@ -378,8 +376,7 @@ public final class Bmgr {
 
         try {
             boolean didRestore = false;
-            String curTransport = mBmgr.getCurrentTransport();
-            mRestore = mBmgr.beginRestoreSession(curTransport);
+            mRestore = mBmgr.beginRestoreSession(null, null);
             if (mRestore == null) {
                 System.err.println(BMGR_NOT_RUNNING_ERR);
                 return;
diff --git a/core/java/android/app/backup/BackupManager.java b/core/java/android/app/backup/BackupManager.java
index 52dd707..80656a1 100644
--- a/core/java/android/app/backup/BackupManager.java
+++ b/core/java/android/app/backup/BackupManager.java
@@ -138,8 +138,8 @@ public class BackupManager {
         if (sService != null) {
             RestoreSession session = null;
             try {
-                String transport = sService.getCurrentTransport();
-                IRestoreSession binder = sService.beginRestoreSession(transport);
+                IRestoreSession binder = sService.beginRestoreSession(mContext.getPackageName(),
+                        null);
                 session = new RestoreSession(mContext, binder);
                 result = session.restorePackage(mContext.getPackageName(), observer);
             } catch (RemoteException e) {
@@ -163,8 +163,8 @@ public class BackupManager {
         checkServiceBinder();
         if (sService != null) {
             try {
-                String transport = sService.getCurrentTransport();
-                IRestoreSession binder = sService.beginRestoreSession(transport);
+                // All packages, current transport
+                IRestoreSession binder = sService.beginRestoreSession(null, null);
                 session = new RestoreSession(mContext, binder);
             } catch (RemoteException e) {
                 Log.w(TAG, "beginRestoreSession() couldn't connect");
diff --git a/core/java/android/app/backup/IBackupManager.aidl b/core/java/android/app/backup/IBackupManager.aidl
index 23d6351..8af59df 100644
--- a/core/java/android/app/backup/IBackupManager.aidl
+++ b/core/java/android/app/backup/IBackupManager.aidl
@@ -144,13 +144,25 @@ interface IBackupManager {
     String selectBackupTransport(String transport);
 
     /**
-     * Begin a restore session with the given transport (which may differ from the
-     * currently-active backup transport).
+     * Begin a restore session.  Either or both of packageName and transportID
+     * may be null.  If packageName is non-null, then only the given package will be
+     * considered for restore.  If transportID is null, then the restore will use
+     * the current active transport.
+     * <p>
+     * This method requires the android.permission.BACKUP permission <i>except</i>
+     * when transportID is null and packageName is the name of the caller's own
+     * package.  In that case, the restore session returned is suitable for supporting
+     * the BackupManager.requestRestore() functionality via RestoreSession.restorePackage()
+     * without requiring the app to hold any special permission.
      *
-     * @param transport The name of the transport to use for the restore operation.
+     * @param packageName The name of the single package for which a restore will
+     *        be requested.  May be null, in which case all packages in the restore
+     *        set can be restored.
+     * @param transportID The name of the transport to use for the restore operation.
+     *        May be null, in which case the current active transport is used.
      * @return An interface to the restore session, or null on error.
      */
-    IRestoreSession beginRestoreSession(String transportID);
+    IRestoreSession beginRestoreSession(String packageName, String transportID);
 
     /**
      * Notify the backup manager that a BackupAgent has completed the operation
diff --git a/services/java/com/android/server/BackupManagerService.java b/services/java/com/android/server/BackupManagerService.java
index 6a86076..bebd013 100644
--- a/services/java/com/android/server/BackupManagerService.java
+++ b/services/java/com/android/server/BackupManagerService.java
@@ -2399,15 +2399,45 @@ class BackupManagerService extends IBackupManager.Stub {
     }
 
     // Hand off a restore session
-    public IRestoreSession beginRestoreSession(String transport) {
-        mContext.enforceCallingOrSelfPermission(android.Manifest.permission.BACKUP, "beginRestoreSession");
+    public IRestoreSession beginRestoreSession(String packageName, String transport) {
+        if (DEBUG) Slog.v(TAG, "beginRestoreSession: pkg=" + packageName
+                + " transport=" + transport);
+
+        boolean needPermission = true;
+        if (transport == null) {
+            transport = mCurrentTransport;
+
+            if (packageName != null) {
+                PackageInfo app = null;
+                try {
+                    app = mPackageManager.getPackageInfo(packageName, 0);
+                } catch (NameNotFoundException nnf) {
+                    Slog.w(TAG, "Asked to restore nonexistent pkg " + packageName);
+                    throw new IllegalArgumentException("Package " + packageName + " not found");
+                }
+
+                if (app.applicationInfo.uid == Binder.getCallingUid()) {
+                    // So: using the current active transport, and the caller has asked
+                    // that its own package will be restored.  In this narrow use case
+                    // we do not require the caller to hold the permission.
+                    needPermission = false;
+                }
+            }
+        }
+
+        if (needPermission) {
+            mContext.enforceCallingOrSelfPermission(android.Manifest.permission.BACKUP,
+                    "beginRestoreSession");
+        } else {
+            if (DEBUG) Slog.d(TAG, "restoring self on current transport; no permission needed");
+        }
 
         synchronized(this) {
             if (mActiveRestoreSession != null) {
                 Slog.d(TAG, "Restore session requested but one already active");
                 return null;
             }
-            mActiveRestoreSession = new ActiveRestoreSession(transport);
+            mActiveRestoreSession = new ActiveRestoreSession(packageName, transport);
         }
         return mActiveRestoreSession;
     }
@@ -2427,10 +2457,12 @@ class BackupManagerService extends IBackupManager.Stub {
     class ActiveRestoreSession extends IRestoreSession.Stub {
         private static final String TAG = "RestoreSession";
 
+        private String mPackageName;
         private IBackupTransport mRestoreTransport = null;
         RestoreSet[] mRestoreSets = null;
 
-        ActiveRestoreSession(String transport) {
+        ActiveRestoreSession(String packageName, String transport) {
+            mPackageName = packageName;
             mRestoreTransport = getTransport(transport);
         }
 
@@ -2466,11 +2498,16 @@ class BackupManagerService extends IBackupManager.Stub {
             mContext.enforceCallingOrSelfPermission(android.Manifest.permission.BACKUP,
                     "performRestore");
 
-            if (DEBUG) Slog.d(TAG, "performRestore token=" + Long.toHexString(token)
+            if (DEBUG) Slog.d(TAG, "restoreAll token=" + Long.toHexString(token)
                     + " observer=" + observer);
 
             if (mRestoreTransport == null || mRestoreSets == null) {
-                Slog.e(TAG, "Ignoring performRestore() with no restore set");
+                Slog.e(TAG, "Ignoring restoreAll() with no restore set");
+                return -1;
+            }
+
+            if (mPackageName != null) {
+                Slog.e(TAG, "Ignoring restoreAll() on single-package session");
                 return -1;
             }
 
@@ -2495,6 +2532,14 @@ class BackupManagerService extends IBackupManager.Stub {
         public synchronized int restorePackage(String packageName, IRestoreObserver observer) {
             if (DEBUG) Slog.v(TAG, "restorePackage pkg=" + packageName + " obs=" + observer);
 
+            if (mPackageName != null) {
+                if (! mPackageName.equals(packageName)) {
+                    Slog.e(TAG, "Ignoring attempt to restore pkg=" + packageName
+                            + " on session for package " + mPackageName);
+                    return -1;
+                }
+            }
+
             PackageInfo app = null;
             try {
                 app = mPackageManager.getPackageInfo(packageName, 0);
@@ -2529,6 +2574,7 @@ class BackupManagerService extends IBackupManager.Stub {
             // the app has never been backed up from this device -- there's nothing
             // to do but return failure.
             if (token == 0) {
+                if (DEBUG) Slog.w(TAG, "No data available for this package; not restoring");
                 return -1;
             }
 
@@ -2543,9 +2589,6 @@ class BackupManagerService extends IBackupManager.Stub {
         }
 
         public synchronized void endRestoreSession() {
-            mContext.enforceCallingOrSelfPermission(android.Manifest.permission.BACKUP,
-                    "endRestoreSession");
-
             if (DEBUG) Slog.d(TAG, "endRestoreSession");
 
             synchronized (this) {