DO NOT MERGE. Check provider access for content changes.
For an app to either send or receive content change notifications,
require that they have some level of access to the underlying
provider.
Without these checks, a malicious app could sniff sensitive user data
from the notifications of otherwise private providers.
Test: builds, boots, PoC app now fails
Bug: 32555637
Change-Id: If2dcd45cb0a9f1fb3b93e39fc7b8ae9c34c2fdef
diff --git a/core/java/android/app/ActivityManagerInternal.java b/core/java/android/app/ActivityManagerInternal.java
index 2a17fa6..34e5910 100644
--- a/core/java/android/app/ActivityManagerInternal.java
+++ b/core/java/android/app/ActivityManagerInternal.java
@@ -22,6 +22,11 @@
* @hide Only for use within the system server.
*/
public abstract class ActivityManagerInternal {
+ /**
+ * Verify that calling app has access to the given provider.
+ */
+ public abstract String checkContentProviderAccess(String authority, int userId);
+
// Called by the power manager.
public abstract void goingToSleep();
public abstract void wakingUp();
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 14e75eb..63b5cdc 100755
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -9044,6 +9044,43 @@
}
/**
+ * Check if the calling UID has a possible chance at accessing the provider
+ * at the given authority and user.
+ */
+ public String checkContentProviderAccess(String authority, int userId) {
+ if (userId == UserHandle.USER_ALL) {
+ mContext.enforceCallingOrSelfPermission(
+ Manifest.permission.INTERACT_ACROSS_USERS_FULL, TAG);
+ userId = UserHandle.getCallingUserId();
+ }
+
+ ProviderInfo cpi = null;
+ try {
+ cpi = AppGlobals.getPackageManager().resolveContentProvider(authority,
+ STOCK_PM_FLAGS | PackageManager.GET_URI_PERMISSION_PATTERNS, userId);
+ } catch (RemoteException ignored) {
+ }
+ if (cpi == null) {
+ // TODO: make this an outright failure in a future platform release;
+ // until then anonymous content notifications are unprotected
+ //return "Failed to find provider " + authority + " for user " + userId;
+ return null;
+ }
+
+ ProcessRecord r = null;
+ synchronized (mPidsSelfLocked) {
+ r = mPidsSelfLocked.get(Binder.getCallingPid());
+ }
+ if (r == null) {
+ return "Failed to find PID " + Binder.getCallingPid();
+ }
+
+ synchronized (this) {
+ return checkContentProviderPermissionLocked(cpi, r, userId, true);
+ }
+ }
+
+ /**
* Check if {@link ProcessRecord} has a possible chance at accessing the
* given {@link ProviderInfo}. Final permission checking is always done
* in {@link ContentProvider}.
@@ -19091,6 +19128,11 @@
private final class LocalService extends ActivityManagerInternal {
@Override
+ public String checkContentProviderAccess(String authority, int userId) {
+ return ActivityManagerService.this.checkContentProviderAccess(authority, userId);
+ }
+
+ @Override
public void goingToSleep() {
ActivityManagerService.this.goingToSleep();
}
diff --git a/services/core/java/com/android/server/content/ContentService.java b/services/core/java/com/android/server/content/ContentService.java
index 22141dc..d07d76a 100644
--- a/services/core/java/com/android/server/content/ContentService.java
+++ b/services/core/java/com/android/server/content/ContentService.java
@@ -19,11 +19,14 @@
import android.Manifest;
import android.accounts.Account;
import android.app.ActivityManager;
+import android.app.ActivityManagerInternal;
+import android.app.ActivityManagerNative;
import android.content.ComponentName;
import android.content.ContentResolver;
import android.content.Context;
import android.content.IContentService;
import android.content.ISyncStatusObserver;
+import android.content.Intent;
import android.content.PeriodicSync;
import android.content.pm.PackageManager;
import android.content.SyncAdapterType;
@@ -46,6 +49,8 @@
import android.util.Slog;
import android.util.SparseIntArray;
+import com.android.server.LocalServices;
+
import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.security.InvalidParameterException;
@@ -172,16 +177,17 @@
throw new IllegalArgumentException("You must pass a valid uri and observer");
}
- enforceCrossUserPermission(userHandle,
- "no permission to observe other users' provider view");
+ final int uid = Binder.getCallingUid();
+ final int pid = Binder.getCallingPid();
- if (userHandle < 0) {
- if (userHandle == UserHandle.USER_CURRENT) {
- userHandle = ActivityManager.getCurrentUser();
- } else if (userHandle != UserHandle.USER_ALL) {
- throw new InvalidParameterException("Bad user handle for registerContentObserver: "
- + userHandle);
- }
+ userHandle = handleIncomingUser(uri, pid, uid,
+ Intent.FLAG_GRANT_READ_URI_PERMISSION, userHandle);
+
+ final String msg = LocalServices.getService(ActivityManagerInternal.class)
+ .checkContentProviderAccess(uri.getAuthority(), userHandle);
+ if (msg != null) {
+ Log.w(TAG, "Ignoring content changes for " + uri + " from " + uid + ": " + msg);
+ return;
}
synchronized (mRootNode) {
@@ -224,24 +230,20 @@
+ " from observer " + observer + ", syncToNetwork " + syncToNetwork);
}
- // Notify for any user other than the caller's own requires permission.
- final int callingUserHandle = UserHandle.getCallingUserId();
- if (userHandle != callingUserHandle) {
- mContext.enforceCallingOrSelfPermission(Manifest.permission.INTERACT_ACROSS_USERS,
- "no permission to notify other users");
- }
-
- // We passed the permission check; resolve pseudouser targets as appropriate
- if (userHandle < 0) {
- if (userHandle == UserHandle.USER_CURRENT) {
- userHandle = ActivityManager.getCurrentUser();
- } else if (userHandle != UserHandle.USER_ALL) {
- throw new InvalidParameterException("Bad user handle for notifyChange: "
- + userHandle);
- }
- }
-
final int uid = Binder.getCallingUid();
+ final int pid = Binder.getCallingPid();
+ final int callingUserHandle = UserHandle.getCallingUserId();
+
+ userHandle = handleIncomingUser(uri, pid, uid,
+ Intent.FLAG_GRANT_WRITE_URI_PERMISSION, userHandle);
+
+ final String msg = LocalServices.getService(ActivityManagerInternal.class)
+ .checkContentProviderAccess(uri.getAuthority(), userHandle);
+ if (msg != null) {
+ Log.w(TAG, "Ignoring notify for " + uri + " from " + uid + ": " + msg);
+ return;
+ }
+
// This makes it so that future permission checks will be in the context of this
// process rather than the caller's process. We will restore this before returning.
long identityToken = clearCallingIdentity();
@@ -881,6 +883,24 @@
return service;
}
+ private int handleIncomingUser(Uri uri, int pid, int uid, int modeFlags, int userId) {
+ if (userId == UserHandle.USER_CURRENT) {
+ userId = ActivityManager.getCurrentUser();
+ }
+
+ if (userId == UserHandle.USER_ALL) {
+ mContext.enforceCallingOrSelfPermission(
+ Manifest.permission.INTERACT_ACROSS_USERS_FULL, TAG);
+ } else if (userId < 0) {
+ throw new IllegalArgumentException("Invalid user: " + userId);
+ } else if (userId != UserHandle.getCallingUserId()) {
+ mContext.enforceCallingOrSelfPermission(
+ Manifest.permission.INTERACT_ACROSS_USERS_FULL, TAG);
+ }
+
+ return userId;
+ }
+
/**
* Checks if the request is from the system or an app that has INTERACT_ACROSS_USERS_FULL
* permission, if the userHandle is not for the caller.