KEY_INTENT shouldn't grant permissions.

KEY_INTENT has no business granting any Uri permissions, so remove any grant flags that malicious apps may have tried sneaking in. Also fix ordering bug in general-purpose security check that was allowing FLAG_GRANT_PERSISTABLE to bypass it. Test: builds, boots Bug: 32990341, 32879915 Change-Id: I657455a770c81f045ccce6abbd2291407a1cfb42
LordNerevar · Jun 13, 2017 · d722e78 · d722e78
1 parent 4cb3ae6
commit d722e78
Show file tree

Hide file tree

Showing 2 changed files with 17 additions and 10 deletions.
diff --git a/services/core/java/com/android/server/accounts/AccountManagerService.java b/services/core/java/com/android/server/accounts/AccountManagerService.java
@@ -4704,6 +4704,10 @@ IAccountManagerResponse getResponseAndClose() {
         protected void checkKeyIntent(
                 int authUid,
                 Intent intent) throws SecurityException {
+            intent.setFlags(intent.getFlags() & ~(Intent.FLAG_GRANT_READ_URI_PERMISSION
+                    | Intent.FLAG_GRANT_WRITE_URI_PERMISSION
+                    | Intent.FLAG_GRANT_PERSISTABLE_URI_PERMISSION
+                    | Intent.FLAG_GRANT_PREFIX_URI_PERMISSION));
             long bid = Binder.clearCallingIdentity();
             try {
                 PackageManager pm = mContext.getPackageManager();

diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -8712,6 +8712,19 @@ int checkGrantUriPermissionLocked(int callingUid, String targetPkg, GrantUri gra
             return -1;
         }
 
+        // Bail early if system is trying to hand out permissions directly; it
+        // must always grant permissions on behalf of someone explicit.
+        final int callingAppId = UserHandle.getAppId(callingUid);
+        if ((callingAppId == SYSTEM_UID) || (callingAppId == ROOT_UID)) {
+            if ("com.android.settings.files".equals(grantUri.uri.getAuthority())) {
+                // Exempted authority for cropping user photos in Settings app
+            } else {
+                Slog.w(TAG, "For security reasons, the system cannot issue a Uri permission"
+                        + " grant to " + grantUri + "; use startActivityAsCaller() instead");
+                return -1;
+            }
+        }
+
         final String authority = grantUri.uri.getAuthority();
         final ProviderInfo pi = getProviderInfoLocked(authority, grantUri.sourceUserId,
                 MATCH_DEBUG_TRIAGED_MISSING);
@@ -8807,16 +8820,6 @@ && checkHoldingPermissionsInternalLocked(pm, pi, grantUri, callingUid,
 
         // Third...  does the caller itself have permission to access
         // this uri?
-        final int callingAppId = UserHandle.getAppId(callingUid);
-        if ((callingAppId == SYSTEM_UID) || (callingAppId == ROOT_UID)) {
-            if ("com.android.settings.files".equals(grantUri.uri.getAuthority())) {
-                // Exempted authority for cropping user photos in Settings app
-            } else {
-                Slog.w(TAG, "For security reasons, the system cannot issue a Uri permission"
-                        + " grant to " + grantUri + "; use startActivityAsCaller() instead");
-                return -1;
-            }
-        }
         if (!checkHoldingPermissionsLocked(pm, pi, grantUri, callingUid, modeFlags)) {
             // Require they hold a strong enough Uri permission
             if (!checkUriPermissionLocked(grantUri, callingUid, modeFlags)) {