Add QLDoc to guard and sanitizer

Author: atorralba

java/ql/lib/semmle/code/java/security/IntentUriPermissionManipulation.qll

@@ -38,6 +38,14 @@ private class DefaultIntentUriPermissionManipulationSink extends IntentUriPermis
   }
 }
 
+/**
+ * Sanitizer that prevents access to arbitrary content providers by modifying the Intent in one of
+ * the following ways:
+ * * Removing the flags `FLAG_GRANT_READ_URI_PERMISSION` and `FLAG_GRANT_WRITE_URI_PERMISSION`.
+ * * Setting the flags to a combination that doesn't include `FLAG_GRANT_READ_URI_PERMISSION` or
+ * `FLAG_GRANT_WRITE_URI_PERMISSION`.
+ * * Replacing the data URI.
+ */
 private class IntentFlagsOrDataChangedSanitizer extends IntentUriPermissionManipulationSanitizer {
   IntentFlagsOrDataChangedSanitizer() {
     exists(MethodAccess ma, Method m |
@@ -60,6 +68,20 @@ private class IntentFlagsOrDataChangedSanitizer extends IntentUriPermissionManip
   }
 }
 
+/**
+ * A guard that checks an Intent's flags or data URI to make sure they are trusted.
+ * It matches the following patterns:
+ *
+ * ```java
+ * if (intent.getData().equals("trustedValue")) {}
+ *
+ * if (intent.getFlags() & Intent.FLAG_GRANT_READ_URI_PERMISSION == 0 &&
+ *      intent.getFlags() & Intent.FLAG_GRANT_WRITE_URI_PERMISSION == 0) {}
+ *
+ * if (intent.getFlags() & Intent.FLAG_GRANT_READ_URI_PERMISSION != 0 ||
+ *      intent.getFlags() & Intent.FLAG_GRANT_WRITE_URI_PERMISSION != 0) {}
+ * ```
+ */
 private class IntentFlagsOrDataCheckedGuard extends IntentUriPermissionManipulationGuard {
   Expr condition;