Merge pull request #8302 from aibaars/type-tracking-smallstep

Ruby: TypeTracker: add smallstep for functions that return their arguments

Author: hvitved

ruby/ql/lib/codeql/ruby/typetracking/TypeTrackerSpecific.qll

@@ -11,12 +11,31 @@ class Node = DataFlowPublic::Node;
 
 class TypeTrackingNode = DataFlowPublic::LocalSourceNode;
 
+/** Holds if there is a simple local flow step from `nodeFrom` to `nodeTo` */
 predicate simpleLocalFlowStep = DataFlowPrivate::localFlowStepTypeTracker/2;
 
+/**
+ * Holds if data can flow from `node1` to `node2` in a way that discards call contexts.
+ */
 predicate jumpStep = DataFlowPrivate::jumpStep/2;
 
-/** Holds if there is a level step from `pred` to `succ`. */
-predicate levelStep(Node pred, Node succ) { none() }
+/**
+ * Holds if there is a summarized local flow step from `nodeFrom` to `nodeTo`,
+ * because there is direct flow from a parameter to a return. That is, summarized
+ * steps are not applied recursively.
+ */
+pragma[nomagic]
+private predicate summarizedLocalStep(Node nodeFrom, Node nodeTo) {
+  exists(DataFlowPublic::ParameterNode param, DataFlowPrivate::ReturningNode returnNode |
+    DataFlowPrivate::LocalFlow::getParameterDefNode(param.getParameter())
+        .(TypeTrackingNode)
+        .flowsTo(returnNode) and
+    callStep(nodeTo.asExpr(), nodeFrom, param)
+  )
+}
+
+/** Holds if there is a level step from `nodeFrom` to `nodeTo`. */
+predicate levelStep(Node nodeFrom, Node nodeTo) { summarizedLocalStep(nodeFrom, nodeTo) }
 
 /**
  * Gets the name of a possible piece of content. This will usually include things like
@@ -48,6 +67,13 @@ private predicate viableParam(
   )
 }
 
+private predicate callStep(ExprNodes::CallCfgNode call, Node nodeFrom, Node nodeTo) {
+  exists(DataFlowDispatch::ParameterPosition pos |
+    argumentPositionMatch(call, nodeFrom, pos) and
+    viableParam(call, nodeTo, pos)
+  )
+}
+
 /**
  * Holds if `nodeFrom` steps to `nodeTo` by being passed as a parameter in a call.
  *
@@ -56,10 +82,7 @@ private predicate viableParam(
  * methods is done using API graphs (which uses type tracking).
  */
 predicate callStep(Node nodeFrom, Node nodeTo) {
-  exists(ExprNodes::CallCfgNode call, DataFlowDispatch::ParameterPosition pos |
-    argumentPositionMatch(call, nodeFrom, pos) and
-    viableParam(call, nodeTo, pos)
-  )
+  callStep(_, nodeFrom, nodeTo)
   or
   // In normal data-flow, this will be a local flow step. But for type tracking
   // we model it as a call step, in order to avoid computing a potential

ruby/ql/test/library-tests/dataflow/type-tracker/TypeTracker.expected

@@ -56,6 +56,7 @@ track
 | type_tracker.rb:14:17:14:23 | "hello" | type tracker with call steps | type_tracker.rb:2:16:2:18 | val |
 | type_tracker.rb:14:17:14:23 | "hello" | type tracker with call steps | type_tracker.rb:2:16:2:18 | val |
 | type_tracker.rb:14:17:14:23 | "hello" | type tracker with call steps with content field | type_tracker.rb:7:5:9:7 | self in field |
+| type_tracker.rb:14:17:14:23 | "hello" | type tracker without call steps | type_tracker.rb:14:5:14:13 | call to field= |
 | type_tracker.rb:14:17:14:23 | "hello" | type tracker without call steps | type_tracker.rb:14:17:14:23 | "hello" |
 | type_tracker.rb:14:17:14:23 | "hello" | type tracker without call steps | type_tracker.rb:15:10:15:18 | call to field |
 | type_tracker.rb:14:17:14:23 | "hello" | type tracker without call steps with content field | type_tracker.rb:14:5:14:7 | [post] var |
@@ -72,19 +73,29 @@ trackEnd
 | type_tracker.rb:2:5:5:7 | return return in field= | type_tracker.rb:2:5:5:7 | return return in field= |
 | type_tracker.rb:2:5:5:7 | return return in field= | type_tracker.rb:14:5:14:13 | call to field= |
 | type_tracker.rb:2:5:5:7 | self (field=) | type_tracker.rb:2:5:5:7 | self (field=) |
+| type_tracker.rb:2:5:5:7 | self (field=) | type_tracker.rb:3:9:3:23 | self |
+| type_tracker.rb:2:5:5:7 | self (field=) | type_tracker.rb:3:14:3:17 | self |
 | type_tracker.rb:2:5:5:7 | self (field=) | type_tracker.rb:7:5:9:7 | self in field |
 | type_tracker.rb:2:5:5:7 | self in field= | type_tracker.rb:2:5:5:7 | self in field= |
+| type_tracker.rb:2:5:5:7 | self in field= | type_tracker.rb:3:9:3:23 | self |
+| type_tracker.rb:2:5:5:7 | self in field= | type_tracker.rb:3:14:3:17 | self |
 | type_tracker.rb:2:5:5:7 | self in field= | type_tracker.rb:7:5:9:7 | self in field |
 | type_tracker.rb:2:16:2:18 | val | type_tracker.rb:2:5:5:7 | return return in field= |
 | type_tracker.rb:2:16:2:18 | val | type_tracker.rb:2:16:2:18 | val |
 | type_tracker.rb:2:16:2:18 | val | type_tracker.rb:2:16:2:18 | val |
 | type_tracker.rb:2:16:2:18 | val | type_tracker.rb:2:16:2:18 | val |
 | type_tracker.rb:2:16:2:18 | val | type_tracker.rb:2:16:2:18 | val |
+| type_tracker.rb:2:16:2:18 | val | type_tracker.rb:4:9:4:20 | ... = ... |
+| type_tracker.rb:2:16:2:18 | val | type_tracker.rb:4:9:4:20 | ... = ... |
+| type_tracker.rb:2:16:2:18 | val | type_tracker.rb:4:18:4:20 | val |
+| type_tracker.rb:2:16:2:18 | val | type_tracker.rb:4:18:4:20 | val |
 | type_tracker.rb:2:16:2:18 | val | type_tracker.rb:14:5:14:13 | call to field= |
 | type_tracker.rb:3:9:3:23 | [post] self | type_tracker.rb:3:9:3:23 | [post] self |
+| type_tracker.rb:3:9:3:23 | [post] self | type_tracker.rb:3:14:3:17 | self |
 | type_tracker.rb:3:9:3:23 | [post] self | type_tracker.rb:7:5:9:7 | self in field |
 | type_tracker.rb:3:9:3:23 | call to puts | type_tracker.rb:3:9:3:23 | call to puts |
 | type_tracker.rb:3:9:3:23 | self | type_tracker.rb:3:9:3:23 | self |
+| type_tracker.rb:3:9:3:23 | self | type_tracker.rb:3:14:3:17 | self |
 | type_tracker.rb:3:9:3:23 | self | type_tracker.rb:7:5:9:7 | self in field |
 | type_tracker.rb:3:14:3:17 | [post] self | type_tracker.rb:3:14:3:17 | [post] self |
 | type_tracker.rb:3:14:3:17 | self | type_tracker.rb:3:14:3:17 | self |
@@ -93,9 +104,11 @@ trackEnd
 | type_tracker.rb:3:14:3:23 | call to field | type_tracker.rb:3:14:3:23 | call to field |
 | type_tracker.rb:4:9:4:14 | @field | type_tracker.rb:4:9:4:14 | @field |
 | type_tracker.rb:4:18:4:20 | val | type_tracker.rb:2:5:5:7 | return return in field= |
+| type_tracker.rb:4:18:4:20 | val | type_tracker.rb:4:9:4:20 | ... = ... |
 | type_tracker.rb:4:18:4:20 | val | type_tracker.rb:4:18:4:20 | val |
 | type_tracker.rb:4:18:4:20 | val | type_tracker.rb:14:5:14:13 | call to field= |
 | type_tracker.rb:7:5:9:7 | &block | type_tracker.rb:7:5:9:7 | &block |
+| type_tracker.rb:7:5:9:7 | field | type_tracker.rb:1:1:10:3 | Container |
 | type_tracker.rb:7:5:9:7 | field | type_tracker.rb:7:5:9:7 | field |
 | type_tracker.rb:7:5:9:7 | return return in field | type_tracker.rb:3:14:3:23 | call to field |
 | type_tracker.rb:7:5:9:7 | return return in field | type_tracker.rb:7:5:9:7 | return return in field |
@@ -109,20 +122,36 @@ trackEnd
 | type_tracker.rb:12:1:16:3 | m | type_tracker.rb:12:1:16:3 | m |
 | type_tracker.rb:12:1:16:3 | return return in m | type_tracker.rb:12:1:16:3 | return return in m |
 | type_tracker.rb:12:1:16:3 | self (m) | type_tracker.rb:12:1:16:3 | self (m) |
+| type_tracker.rb:12:1:16:3 | self (m) | type_tracker.rb:15:5:15:18 | self |
 | type_tracker.rb:12:1:16:3 | self in m | type_tracker.rb:12:1:16:3 | self in m |
+| type_tracker.rb:12:1:16:3 | self in m | type_tracker.rb:15:5:15:18 | self |
 | type_tracker.rb:13:5:13:7 | var | type_tracker.rb:13:5:13:7 | var |
 | type_tracker.rb:13:11:13:19 | Container | type_tracker.rb:13:11:13:19 | Container |
 | type_tracker.rb:13:11:13:19 | [post] Container | type_tracker.rb:13:11:13:19 | [post] Container |
 | type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:2:5:5:7 | self in field= |
+| type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:3:9:3:23 | self |
+| type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:3:14:3:17 | self |
 | type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:7:5:9:7 | self in field |
+| type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:13:5:13:23 | ... = ... |
+| type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:13:5:13:23 | ... = ... |
 | type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:13:11:13:23 | call to new |
+| type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:14:5:14:7 | var |
+| type_tracker.rb:13:11:13:23 | call to new | type_tracker.rb:15:10:15:12 | var |
 | type_tracker.rb:14:5:14:7 | [post] var | type_tracker.rb:7:5:9:7 | self in field |
 | type_tracker.rb:14:5:14:7 | [post] var | type_tracker.rb:14:5:14:7 | [post] var |
+| type_tracker.rb:14:5:14:7 | [post] var | type_tracker.rb:15:10:15:12 | var |
 | type_tracker.rb:14:5:14:13 | [post] ... = ... | type_tracker.rb:14:5:14:13 | [post] ... = ... |
 | type_tracker.rb:14:5:14:13 | __synth__0 | type_tracker.rb:14:5:14:13 | __synth__0 |
 | type_tracker.rb:14:5:14:13 | call to field= | type_tracker.rb:14:5:14:13 | call to field= |
 | type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:2:16:2:18 | val |
 | type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:2:16:2:18 | val |
+| type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:4:9:4:20 | ... = ... |
+| type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:4:18:4:20 | val |
+| type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:14:5:14:13 | ... = ... |
+| type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:14:5:14:13 | ... = ... |
+| type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:14:5:14:13 | __synth__0 |
+| type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:14:5:14:13 | call to field= |
+| type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:14:5:14:23 | ... |
 | type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:14:17:14:23 | "hello" |
 | type_tracker.rb:14:17:14:23 | "hello" | type_tracker.rb:15:10:15:18 | call to field |
 | type_tracker.rb:15:5:15:18 | [post] self | type_tracker.rb:15:5:15:18 | [post] self |

ruby/ql/test/library-tests/dataflow/type-tracker/TypeTracker.ql

@@ -13,6 +13,9 @@ query predicate track(LocalSourceNode src, TypeTracker t, LocalSourceNode dst) {
   exists(TypeTracker t2, LocalSourceNode mid | track(src, t2, mid) and dst = mid.track(t2, t))
 }
 
-query predicate trackEnd(LocalSourceNode src, LocalSourceNode dst) {
-  track(src, TypeTracker::end(), dst)
+query predicate trackEnd(LocalSourceNode src, DataFlow::Node dst) {
+  exists(LocalSourceNode end |
+    track(src, TypeTracker::end(), end) and
+    end.flowsTo(dst)
+  )
 }