Move tainted path ad-hoc guard back.

Author: intrigus

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

@@ -16,6 +16,7 @@ import java
 import semmle.code.java.dataflow.FlowSources
 import semmle.code.java.security.PathCreation
 import DataFlow::PathGraph
+import TaintedPathCommon
 
 class ContainsDotDotSanitizer extends DataFlow::BarrierGuard {
   ContainsDotDotSanitizer() {

java/ql/src/Security/CWE/CWE-022/TaintedPathCommon.qll

@@ -0,0 +1,33 @@
+/**
+ * Models a very basic guard for the tainted path queries.
+ */
+
+import java
+import semmle.code.java.controlflow.Guards
+import semmle.code.java.security.PathCreation
+
+private predicate inWeakCheck(Expr e) {
+  // None of these are sufficient to guarantee that a string is safe.
+  exists(MethodAccess m, Method def | m.getQualifier() = e and m.getMethod() = def |
+    def.getName() = "startsWith" or
+    def.getName() = "endsWith" or
+    def.getName() = "isEmpty" or
+    def.getName() = "equals"
+  )
+  or
+  // Checking against `null` has no bearing on path traversal.
+  exists(EqualityTest b | b.getAnOperand() = e | b.getAnOperand() instanceof NullLiteral)
+}
+
+// Ignore cases where the variable has been checked somehow,
+// but allow some particularly obviously bad cases.
+predicate guarded(VarAccess e) {
+  exists(PathCreation p | e = p.getAnInput()) and
+  exists(ConditionBlock cb, Expr c |
+    cb.getCondition().getAChildExpr*() = c and
+    c = e.getVariable().getAnAccess() and
+    cb.controls(e.getBasicBlock(), true) and
+    // Disallow a few obviously bad checks.
+    not inWeakCheck(c)
+  )
+}

java/ql/src/Security/CWE/CWE-022/TaintedPathLocal.ql

@@ -16,13 +16,16 @@ import java
 import semmle.code.java.dataflow.FlowSources
 import semmle.code.java.security.PathCreation
 import DataFlow::PathGraph
+import TaintedPathCommon
 
 class TaintedPathLocalConfig extends TaintTracking::Configuration {
   TaintedPathLocalConfig() { this = "TaintedPathLocalConfig" }
 
   override predicate isSource(DataFlow::Node source) { source instanceof LocalUserInput }
 
-  override predicate isSink(DataFlow::Node sink) { sink.asExpr() = any(PathCreation p).getAnInput() }
+  override predicate isSink(DataFlow::Node sink) {
+    sink.asExpr() = any(PathCreation p).getAnInput()
+  }
 }
 
 from

java/ql/src/semmle/code/java/security/PathCreation.qll

@@ -3,7 +3,6 @@
  */
 
 import java
-import semmle.code.java.controlflow.Guards
 
 /** Models the creation of a path. */
 abstract class PathCreation extends Expr {
@@ -140,29 +139,3 @@ private class FileOutputStreamCreation extends PathCreation, ClassInstanceExpr {
     result.getType() instanceof TypeString
   }
 }
-
-private predicate inWeakCheck(Expr e) {
-  // None of these are sufficient to guarantee that a string is safe.
-  exists(MethodAccess m, Method def | m.getQualifier() = e and m.getMethod() = def |
-    def.getName() = "startsWith" or
-    def.getName() = "endsWith" or
-    def.getName() = "isEmpty" or
-    def.getName() = "equals"
-  )
-  or
-  // Checking against `null` has no bearing on path traversal.
-  exists(EqualityTest b | b.getAnOperand() = e | b.getAnOperand() instanceof NullLiteral)
-}
-
-// Ignore cases where the variable has been checked somehow,
-// but allow some particularly obviously bad cases.
-predicate guarded(VarAccess e) {
-  exists(PathCreation p | e = p.getAnInput()) and
-  exists(ConditionBlock cb, Expr c |
-    cb.getCondition().getAChildExpr*() = c and
-    c = e.getVariable().getAnAccess() and
-    cb.controls(e.getBasicBlock(), true) and
-    // Disallow a few obviously bad checks.
-    not inWeakCheck(c)
-  )
-}