[quandary] add support for C++ parameter passing modes that differ from Java

Summary:
There are two pointer-related operations you can do in C++ but not Java that we need to support in taint analysis:
(1) `*formal_ptr = ...` when `formal_ptr` is a formal that's a pointer type. Java doesn't have raw pointers, so we didn't need to handle this case.
(2) Passing by reference, which Java also doesn't have (everything is pass-by-value).

Reviewed By: mbouaziz

Differential Revision: D5041246

fbshipit-source-id: 4e8f962

infer/src/quandary/TaintAnalysis.ml

@@ -441,7 +441,11 @@ module Make (TaintSpecification : TaintSpec.S) = struct
   module Analyzer =
     AbstractInterpreter.Make (ProcCfg.Exceptional) (LowerHil.Make(TransferFunctions))
 
-  let make_summary formal_map access_tree =
+  let make_summary { ProcData.pdesc; extras={ formal_map; } } access_tree =
+    let is_java = match Procdesc.get_proc_name pdesc with
+      | Java _ -> true
+      | _ -> false in
+
     (* if a trace has footprint sources, attach them to the appropriate footprint var *)
     let access_tree' =
       TaintDomain.fold
@@ -469,7 +473,13 @@ module Make (TaintSpecification : TaintSpec.S) = struct
 
     (* should only be used on nodes associated with a footprint base *)
     let is_empty_node (trace, tree) =
-      TraceDomain.Sinks.is_empty (TraceDomain.sinks trace) &&
+      (* In C++, we can reassign the value pointed to by a pointer type formal, and we can assign
+         to a value type passed by reference. these mechanisms can be used to associate a source
+         directly with a formal. In Java this can't happen, so we only care if the formal flows to
+         a sink *)
+      (if is_java
+       then TraceDomain.Sinks.is_empty (TraceDomain.sinks trace)
+       else TraceDomain.is_empty trace) &&
       match tree with
       | TaintDomain.Subtree subtree -> TaintDomain.AccessMap.is_empty subtree
       | TaintDomain.Star -> true in
@@ -500,10 +510,8 @@ module Make (TaintSpecification : TaintSpec.S) = struct
                    try TaintDomain.node_join (AccessPath.BaseMap.find base' acc) node
                    with Not_found -> node in
                  if is_empty_node joined_node
-                 then
-                   acc
-                 else
-                   AccessPath.BaseMap.add base' joined_node acc
+                 then acc
+                 else AccessPath.BaseMap.add base' joined_node acc
              | None ->
                  (* base is a local var *)
                  acc)
@@ -542,7 +550,7 @@ module Make (TaintSpecification : TaintSpec.S) = struct
       let initial = make_initial proc_data.pdesc in
       match Analyzer.compute_post proc_data ~initial with
       | Some (access_tree, _) ->
-          Some (make_summary proc_data.extras.formal_map access_tree)
+          Some (make_summary proc_data access_tree)
       | None ->
           if Procdesc.Node.get_succs (Procdesc.get_start_node proc_data.pdesc) <> []
           then failwith "Couldn't compute post"

infer/tests/codetoanalyze/cpp/quandary/basics.cpp

@@ -125,8 +125,7 @@ void via_passthrough_bad1(Obj* obj) {
   obj->string_sink(*laundered_source);
 }
 
-// the summary for id2 doesn't assign to the return value
-void FN_via_passthrough_bad2(Obj* obj) {
+void via_passthrough_bad2(Obj* obj) {
   std::string source = obj->string_source(0);
   std::string laundered_source = id2<std::string>(source);
   obj->string_sink(laundered_source);

infer/tests/codetoanalyze/cpp/quandary/issues.exp

@@ -17,6 +17,7 @@ codetoanalyze/cpp/quandary/basics.cpp, basics::template_source_bad, 2, QUANDARY_
 codetoanalyze/cpp/quandary/basics.cpp, basics::via_field_bad1, 3, QUANDARY_TAINT_ERROR, [return from basics::template_source<std::basic_string<char>_>,call to basics::template_sink<std::basic_string<char>_>]
 codetoanalyze/cpp/quandary/basics.cpp, basics::via_field_bad2, 2, QUANDARY_TAINT_ERROR, [return from basics::template_source<std::basic_string<char>_>,call to basics::template_sink<std::basic_string<char>_>]
 codetoanalyze/cpp/quandary/basics.cpp, basics::via_passthrough_bad1, 4, QUANDARY_TAINT_ERROR, [return from basics::Obj_string_source,flow through basics::id1<std::basic_string<char>_>,call to basics::Obj_string_sink]
+codetoanalyze/cpp/quandary/basics.cpp, basics::via_passthrough_bad2, 3, QUANDARY_TAINT_ERROR, [return from basics::Obj_string_source,flow through basics::id2<std::basic_string<char>_>,call to basics::Obj_string_sink]
 codetoanalyze/cpp/quandary/execs.cpp, execs::callExecBad, 6, QUANDARY_TAINT_ERROR, [return from getenv,call to execl]
 codetoanalyze/cpp/quandary/execs.cpp, execs::callExecBad, 8, QUANDARY_TAINT_ERROR, [return from getenv,call to execl]
 codetoanalyze/cpp/quandary/execs.cpp, execs::callExecBad, 11, QUANDARY_TAINT_ERROR, [return from getenv,call to execl]
@@ -32,3 +33,9 @@ codetoanalyze/cpp/quandary/files.cpp, files::read_file_call_exec_bad1, 5, QUANDA
 codetoanalyze/cpp/quandary/files.cpp, files::read_file_call_exec_bad2, 5, QUANDARY_TAINT_ERROR, [return from std::basic_istream<char,std::char_traits<char>>_readsome,call to execle]
 codetoanalyze/cpp/quandary/files.cpp, files::read_file_call_exec_bad3, 5, QUANDARY_TAINT_ERROR, [return from std::basic_istream<char,std::char_traits<char>>_getline,call to execle]
 codetoanalyze/cpp/quandary/files.cpp, files::read_file_call_exec_bad5, 4, QUANDARY_TAINT_ERROR, [return from std::basic_istream<char,std::char_traits<char>>_getline,call to execle]
+codetoanalyze/cpp/quandary/pointers.cpp, pointers::FP_reuse_pointer_as_local_ok, 2, QUANDARY_TAINT_ERROR, [return from __infer_taint_source,return from pointers::reuse_pointer_as_local,call to __infer_taint_sink]
+codetoanalyze/cpp/quandary/pointers.cpp, pointers::assign_pointer_pass_to_sink_bad1, 2, QUANDARY_TAINT_ERROR, [return from __infer_taint_source,return from pointers::assign_pointer_to_source,call to __infer_taint_sink]
+codetoanalyze/cpp/quandary/pointers.cpp, pointers::assign_pointer_pass_to_sink_bad2, 3, QUANDARY_TAINT_ERROR, [return from __infer_taint_source,return from pointers::assign_pointer_to_source,call to __infer_taint_sink]
+codetoanalyze/cpp/quandary/pointers.cpp, pointers::assign_source_by_reference_bad1, 3, QUANDARY_TAINT_ERROR, [return from __infer_taint_source,return from pointers::assign_source_by_reference,call to __infer_taint_sink]
+codetoanalyze/cpp/quandary/pointers.cpp, pointers::assign_source_by_reference_bad2, 2, QUANDARY_TAINT_ERROR, [return from __infer_taint_source,return from pointers::assign_source_by_reference,call to __infer_taint_sink]
+codetoanalyze/cpp/quandary/pointers.cpp, pointers::assign_source_by_reference_bad3, 3, QUANDARY_TAINT_ERROR, [return from __infer_taint_source,return from pointers::assign_source_by_reference,return from pointers::call_assign_source_by_reference,call to __infer_taint_sink]

infer/tests/codetoanalyze/cpp/quandary/pointers.cpp

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2016 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include <string>
+
+extern std::string* __infer_taint_source();
+extern void __infer_taint_sink(std::string);
+
+namespace pointers {
+
+void assign_pointer_to_source(std::string* pointer) {
+  *pointer = *__infer_taint_source();
+}
+
+void assign_pointer_pass_to_sink_bad1(std::string* pointer) {
+  assign_pointer_to_source(pointer);
+  __infer_taint_sink(*pointer);
+}
+
+void assign_pointer_pass_to_sink_bad2() {
+  std::string* pointer = new std::string();
+  assign_pointer_to_source(pointer);
+  __infer_taint_sink(*pointer);
+}
+
+void assign_source_by_reference(std::string& reference) {
+  reference = *__infer_taint_source();
+}
+
+void assign_source_by_reference_bad1() {
+  std::string local;
+  assign_source_by_reference(local);
+  __infer_taint_sink(local);
+}
+
+void assign_source_by_reference_bad2(std::string formal) {
+  assign_source_by_reference(formal);
+  __infer_taint_sink(formal);
+}
+
+void call_assign_source_by_reference(std::string& formal) {
+  assign_source_by_reference(formal);
+}
+
+void assign_source_by_reference_bad3() {
+  std::string local;
+  call_assign_source_by_reference(local);
+  __infer_taint_sink(local);
+}
+
+void reuse_pointer_as_local(std::string* pointer) {
+  pointer = __infer_taint_source();
+}
+
+// need to understand that assigning a reference doesn't change the value in the
+// caller
+void FP_reuse_pointer_as_local_ok(std::string* pointer) {
+  reuse_pointer_as_local(pointer);
+  __infer_taint_sink(*pointer);
+}
+}