From c813f5dae231bd8f01864227c5dba10d43a89249 Mon Sep 17 00:00:00 2001 From: Jeff Sharkey Date: Wed, 16 Nov 2016 17:22:48 -0700 Subject: 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 --- core/java/android/app/ActivityManagerInternal.java | 5 ++ .../android/server/am/ActivityManagerService.java | 45 ++++++++++++++ .../com/android/server/content/ContentService.java | 72 ++++++++++++---------- 3 files changed, 88 insertions(+), 34 deletions(-) diff --git a/core/java/android/app/ActivityManagerInternal.java b/core/java/android/app/ActivityManagerInternal.java index 0ba937a3f16b..d4f80a01ea53 100644 --- a/core/java/android/app/ActivityManagerInternal.java +++ b/core/java/android/app/ActivityManagerInternal.java @@ -60,6 +60,11 @@ public abstract class ActivityManagerInternal { */ public static final int APP_TRANSITION_TIMEOUT = 3; + /** + * 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 onWakefulnessChanged(int wakefulness); diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java index 85d2981aaa96..5a99d6fdddcb 100644 --- a/services/core/java/com/android/server/am/ActivityManagerService.java +++ b/services/core/java/com/android/server/am/ActivityManagerService.java @@ -10390,6 +10390,46 @@ public final class ActivityManagerService extends ActivityManagerNative return providers; } + /** + * 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 + | PackageManager.MATCH_DIRECT_BOOT_AWARE + | PackageManager.MATCH_DIRECT_BOOT_UNAWARE, + 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 @@ -21845,6 +21885,11 @@ public final class ActivityManagerService extends ActivityManagerNative } private final class LocalService extends ActivityManagerInternal { + @Override + public String checkContentProviderAccess(String authority, int userId) { + return ActivityManagerService.this.checkContentProviderAccess(authority, userId); + } + @Override public void onWakefulnessChanged(int wakefulness) { ActivityManagerService.this.onWakefulnessChanged(wakefulness); diff --git a/services/core/java/com/android/server/content/ContentService.java b/services/core/java/com/android/server/content/ContentService.java index 07276298d66d..243439079031 100644 --- a/services/core/java/com/android/server/content/ContentService.java +++ b/services/core/java/com/android/server/content/ContentService.java @@ -20,12 +20,12 @@ import android.Manifest; import android.accounts.Account; import android.annotation.Nullable; import android.app.ActivityManager; +import android.app.ActivityManagerInternal; import android.app.ActivityManagerNative; import android.app.AppOpsManager; import android.app.job.JobInfo; import android.content.BroadcastReceiver; import android.content.ComponentName; -import android.content.ContentProvider; import android.content.ContentResolver; import android.content.Context; import android.content.IContentService; @@ -66,7 +66,6 @@ import com.android.server.SystemService; import java.io.FileDescriptor; import java.io.PrintWriter; -import java.security.InvalidParameterException; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; @@ -296,24 +295,15 @@ public final class ContentService extends IContentService.Stub { final int uid = Binder.getCallingUid(); final int pid = Binder.getCallingPid(); - final int callingUserHandle = UserHandle.getCallingUserId(); - // Registering an observer for any user other than the calling user requires uri grant or - // cross user permission - if (callingUserHandle != userHandle) { - if (checkUriPermission(uri, pid, uid, Intent.FLAG_GRANT_READ_URI_PERMISSION, userHandle) - != PackageManager.PERMISSION_GRANTED) { - enforceCrossUserPermission(userHandle, - "no permission to observe other users' provider view"); - } - } - 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) { @@ -363,22 +353,15 @@ public final class ContentService extends IContentService.Stub { final int uid = Binder.getCallingUid(); final int pid = Binder.getCallingPid(); final int callingUserHandle = UserHandle.getCallingUserId(); - // Notify for any user other than the caller requires uri grant or cross user permission - if (callingUserHandle != userHandle) { - if (checkUriPermission(uri, pid, uid, Intent.FLAG_GRANT_WRITE_URI_PERMISSION, - userHandle) != PackageManager.PERMISSION_GRANTED) { - enforceCrossUserPermission(userHandle, "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); - } + 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 @@ -1143,6 +1126,27 @@ public final class ContentService extends IContentService.Stub { } } + 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()) { + if (checkUriPermission(uri, pid, uid, modeFlags, + userId) != PackageManager.PERMISSION_GRANTED) { + 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. -- cgit v1.2.3-59-g8ed1b