C++: Path explanations in DefaultTaintTracking

The first three queries are migrated to use path explanations.

cpp/ql/src/Security/CWE/CWE-022/TaintedPath.ql

@@ -2,7 +2,7 @@
  * @name Uncontrolled data used in path expression
  * @description Accessing paths influenced by users can allow an
  *              attacker to access unexpected resources.
- * @kind problem
+ * @kind path-problem
  * @problem.severity warning
  * @precision medium
  * @id cpp/path-injection
@@ -17,6 +17,7 @@ import cpp
 import semmle.code.cpp.security.FunctionWithWrappers
 import semmle.code.cpp.security.Security
 import semmle.code.cpp.security.TaintTracking
+import TaintedWithPath
 
 /**
  * A function for opening a file.
@@ -51,12 +52,19 @@ class FileFunction extends FunctionWithWrappers {
   override predicate interestingArg(int arg) { arg = 0 }
 }
 
+class TaintedPathConfiguration extends TaintTrackingConfiguration {
+  override predicate isSink(Element tainted) {
+    exists(FileFunction fileFunction | fileFunction.outermostWrapperFunctionCall(tainted, _))
+  }
+}
+
 from
-  FileFunction fileFunction, Expr taintedArg, Expr taintSource, string taintCause, string callChain
+  FileFunction fileFunction, Expr taintedArg, Expr taintSource, PathNode sourceNode,
+  PathNode sinkNode, string taintCause, string callChain
 where
   fileFunction.outermostWrapperFunctionCall(taintedArg, callChain) and
-  tainted(taintSource, taintedArg) and
+  taintedWithPath(taintSource, taintedArg, sourceNode, sinkNode) and
   isUserInput(taintSource, taintCause)
-select taintedArg,
+select taintedArg, sourceNode, sinkNode,
   "This argument to a file access function is derived from $@ and then passed to " + callChain,
   taintSource, "user input (" + taintCause + ")"

cpp/ql/src/Security/CWE/CWE-134/UncontrolledFormatString.ql

@@ -3,7 +3,7 @@
  * @description Using externally-controlled format strings in
  *              printf-style functions can lead to buffer overflows
  *              or data representation problems.
- * @kind problem
+ * @kind path-problem
  * @problem.severity warning
  * @precision medium
  * @id cpp/tainted-format-string
@@ -16,12 +16,20 @@ import cpp
 import semmle.code.cpp.security.Security
 import semmle.code.cpp.security.FunctionWithWrappers
 import semmle.code.cpp.security.TaintTracking
+import TaintedWithPath
 
-from PrintfLikeFunction printf, Expr arg, string printfFunction, Expr userValue, string cause
+class TaintedPathConfiguration extends TaintTrackingConfiguration {
+  override predicate isSink(Element tainted) {
+    exists(PrintfLikeFunction printf | printf.outermostWrapperFunctionCall(tainted, _))
+  }
+}
+
+from PrintfLikeFunction printf, Expr arg, PathNode sourceNode,
+  PathNode sinkNode, string printfFunction, Expr userValue, string cause
 where
   printf.outermostWrapperFunctionCall(arg, printfFunction) and
-  tainted(userValue, arg) and
+  taintedWithPath(userValue, arg, sourceNode, sinkNode) and
   isUserInput(userValue, cause)
-select arg,
+select arg, sourceNode, sinkNode,
   "The value of this argument may come from $@ and is being used as a formatting argument to " +
     printfFunction, userValue, cause

cpp/ql/src/Security/CWE/CWE-190/TaintedAllocationSize.ql

@@ -2,7 +2,7 @@
  * @name Overflow in uncontrolled allocation size
  * @description Allocating memory with a size controlled by an external
  *              user can result in integer overflow.
- * @kind problem
+ * @kind path-problem
  * @problem.severity error
  * @precision high
  * @id cpp/uncontrolled-allocation-size
@@ -13,21 +13,33 @@
 
 import cpp
 import semmle.code.cpp.security.TaintTracking
+import TaintedWithPath
 
-predicate taintedAllocSize(Expr e, Expr source, string taintCause) {
+predicate taintedChild(Expr e, Expr tainted) {
   (
-    isAllocationExpr(e) or
+    isAllocationExpr(e)
+    or
     any(MulExpr me | me.getAChild() instanceof SizeofOperator) = e
   ) and
+  tainted = e.getAChild() and
+  tainted.getUnspecifiedType() instanceof IntegralType
+}
+
+class TaintedAllocationSizeConfiguration extends TaintTrackingConfiguration {
+  override predicate isSink(Element tainted) { taintedChild(_, tainted) }
+}
+
+predicate taintedAllocSize(
+  Expr e, Expr source, PathNode sourceNode, PathNode sinkNode, string taintCause
+) {
+  isUserInput(source, taintCause) and
   exists(Expr tainted |
-    tainted = e.getAChild() and
-    tainted.getUnspecifiedType() instanceof IntegralType and
-    isUserInput(source, taintCause) and
-    tainted(source, tainted)
+    taintedChild(e, tainted) and
+    taintedWithPath(source, tainted, sourceNode, sinkNode)
   )
 }
 
-from Expr e, Expr source, string taintCause
-where taintedAllocSize(e, source, taintCause)
-select e, "This allocation size is derived from $@ and might overflow", source,
-  "user input (" + taintCause + ")"
+from Expr e, Expr source, PathNode sourceNode, PathNode sinkNode, string taintCause
+where taintedAllocSize(e, source, sourceNode, sinkNode, taintCause)
+select e, sourceNode, sinkNode, "This allocation size is derived from $@ and might overflow",
+  source, "user input (" + taintCause + ")"