Merge branch 'main' into rdmarsh2/dataflow-global-vars

cpp/ql/lib/semmle/code/cpp/UserType.qll

@@ -48,8 +48,8 @@ class UserType extends Type, Declaration, NameQualifyingElement, AccessHolder, @
   }
 
   override TypeDeclarationEntry getADeclarationEntry() {
-    if type_decls(_, underlyingElement(this), _)
-    then type_decls(unresolveElement(result), underlyingElement(this), _)
+    if type_decls(_, unresolveElement(this), _)
+    then type_decls(underlyingElement(result), unresolveElement(this), _)
     else exists(Class t | this.(Class).isConstructedFrom(t) and result = t.getADeclarationEntry())
   }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl2.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl3.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImpl4.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowImplLocal.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/DataFlowUtil.qll

@@ -850,6 +850,34 @@ class ContentSet instanceof Content {
 }
 
 /**
+ * Holds if the guard `g` validates the expression `e` upon evaluating to `branch`.
+ *
+ * The expression `e` is expected to be a syntactic part of the guard `g`.
+ * For example, the guard `g` might be a call `isSafe(x)` and the expression `e`
+ * the argument `x`.
+ */
+signature predicate guardChecksSig(GuardCondition g, Expr e, boolean branch);
+
+/**
+ * Provides a set of barrier nodes for a guard that validates an expression.
+ *
+ * This is expected to be used in `isBarrier`/`isSanitizer` definitions
+ * in data flow and taint tracking.
+ */
+module BarrierGuard<guardChecksSig/3 guardChecks> {
+  /** Gets a node that is safely guarded by the given guard check. */
+  ExprNode getABarrierNode() {
+    exists(GuardCondition g, SsaDefinition def, Variable v, boolean branch |
+      result.getExpr() = def.getAUse(v) and
+      guardChecks(g, def.getAUse(v), branch) and
+      g.controls(result.getExpr().getBasicBlock(), branch)
+    )
+  }
+}
+
+/**
+ * DEPRECATED: Use `BarrierGuard` module instead.
+ *
  * A guard that validates some expression.
  *
  * To use this in a configuration, extend the class and provide a
@@ -858,7 +886,7 @@ class ContentSet instanceof Content {
  *
  * It is important that all extending classes in scope are disjoint.
  */
-class BarrierGuard extends GuardCondition {
+deprecated class BarrierGuard extends GuardCondition {
   /** Override this predicate to hold if this guard validates `e` upon evaluating to `b`. */
   abstract predicate checks(Expr e, boolean b);
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/TaintTrackingUtil.qll

@@ -47,12 +47,6 @@ predicate defaultImplicitTaintRead(DataFlow::Node node, DataFlow::Content c) { n
  */
 predicate defaultTaintSanitizer(DataFlow::Node node) { none() }
 
-/**
- * Holds if `guard` should be a sanitizer guard in all global taint flow configurations
- * but not in local taint.
- */
-predicate defaultTaintSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
-
 /**
  * Holds if taint can flow in one local step from `nodeFrom` to `nodeTo` excluding
  * local data flow steps. That is, `nodeFrom` and `nodeTo` are likely to represent

cpp/ql/lib/semmle/code/cpp/dataflow/internal/tainttracking1/TaintTrackingImpl.qll

@@ -116,20 +116,30 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
+   * Holds if taint propagation through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
-    this.isSanitizerGuard(guard) or defaultTaintSanitizerGuard(guard)
+  deprecated final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
   }
 
   /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
    * Holds if taint propagation through nodes guarded by `guard` is prohibited
    * when the flow state is `state`.
    */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) { none() }
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+    none()
+  }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+  deprecated final override predicate isBarrierGuard(
+    DataFlow::BarrierGuard guard, DataFlow::FlowState state
+  ) {
     this.isSanitizerGuard(guard, state)
   }
 

cpp/ql/lib/semmle/code/cpp/dataflow/internal/tainttracking2/TaintTrackingImpl.qll

@@ -116,20 +116,30 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
+   * Holds if taint propagation through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
-    this.isSanitizerGuard(guard) or defaultTaintSanitizerGuard(guard)
+  deprecated final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
   }
 
   /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
    * Holds if taint propagation through nodes guarded by `guard` is prohibited
    * when the flow state is `state`.
    */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) { none() }
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+    none()
+  }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+  deprecated final override predicate isBarrierGuard(
+    DataFlow::BarrierGuard guard, DataFlow::FlowState state
+  ) {
     this.isSanitizerGuard(guard, state)
   }
 

cpp/ql/lib/semmle/code/cpp/internal/QualifiedName.qll

@@ -4,11 +4,7 @@
  * qualified.
  *
  * This file contains classes that mirror the standard AST classes for C++, but
- * these classes are only concerned with naming. The other difference is that
- * these classes don't use the `ResolveClass.qll` mechanisms like
- * `unresolveElement` because these classes should eventually be part of the
- * implementation of `ResolveClass.qll`, allowing it to match up classes when
- * their qualified names and parameters match.
+ * these classes are only concerned with naming.
  */
 
 private import semmle.code.cpp.Declaration as D

cpp/ql/lib/semmle/code/cpp/internal/ResolveClass.qll

@@ -115,15 +115,13 @@ private module Cached {
    */
   cached
   predicate isClass(@usertype t) {
-    (
-      usertypes(t, _, 1) or
-      usertypes(t, _, 2) or
-      usertypes(t, _, 3) or
-      usertypes(t, _, 6) or
-      usertypes(t, _, 10) or
-      usertypes(t, _, 11) or
-      usertypes(t, _, 12)
-    )
+    usertypes(t, _, 1) or
+    usertypes(t, _, 2) or
+    usertypes(t, _, 3) or
+    usertypes(t, _, 6) or
+    usertypes(t, _, 10) or
+    usertypes(t, _, 11) or
+    usertypes(t, _, 12)
   }
 
   cached

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl2.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl3.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowImpl4.qll

@@ -90,14 +90,20 @@ abstract class Configuration extends string {
   /** Holds if data flow out of `node` is prohibited. */
   predicate isBarrierOut(Node node) { none() }
 
-  /** Holds if data flow through nodes guarded by `guard` is prohibited. */
-  predicate isBarrierGuard(BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
+   * Holds if data flow through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isBarrierGuard(BarrierGuard guard) { none() }
 
   /**
+   * DEPRECATED: Use `isBarrier` and `BarrierGuard` module instead.
+   *
    * Holds if data flow through nodes guarded by `guard` is prohibited when
    * the flow state is `state`
    */
-  predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
+  deprecated predicate isBarrierGuard(BarrierGuard guard, FlowState state) { none() }
 
   /**
    * Holds if data may flow from `node1` to `node2` in addition to the normal data-flow steps.
@@ -335,6 +341,29 @@ private predicate outBarrier(NodeEx node, Configuration config) {
   )
 }
 
+/** A bridge class to access the deprecated `isBarrierGuard`. */
+private class BarrierGuardGuardedNodeBridge extends Unit {
+  abstract predicate guardedNode(Node n, Configuration config);
+
+  abstract predicate guardedNode(Node n, FlowState state, Configuration config);
+}
+
+private class BarrierGuardGuardedNode extends BarrierGuardGuardedNodeBridge {
+  deprecated override predicate guardedNode(Node n, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g) and
+      n = g.getAGuardedNode()
+    )
+  }
+
+  deprecated override predicate guardedNode(Node n, FlowState state, Configuration config) {
+    exists(BarrierGuard g |
+      config.isBarrierGuard(g, state) and
+      n = g.getAGuardedNode()
+    )
+  }
+}
+
 pragma[nomagic]
 private predicate fullBarrier(NodeEx node, Configuration config) {
   exists(Node n | node.asNode() = n |
@@ -348,10 +377,7 @@ private predicate fullBarrier(NodeEx node, Configuration config) {
     not config.isSink(n) and
     not config.isSink(n, _)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, config)
   )
 }
 
@@ -360,10 +386,7 @@ private predicate stateBarrier(NodeEx node, FlowState state, Configuration confi
   exists(Node n | node.asNode() = n |
     config.isBarrier(n, state)
     or
-    exists(BarrierGuard g |
-      config.isBarrierGuard(g, state) and
-      n = g.getAGuardedNode()
-    )
+    any(BarrierGuardGuardedNodeBridge b).guardedNode(n, state, config)
   )
 }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll

@@ -1092,6 +1092,56 @@ class ContentSet instanceof Content {
 }
 
 /**
+ * Holds if the guard `g` validates the expression `e` upon evaluating to `branch`.
+ *
+ * The expression `e` is expected to be a syntactic part of the guard `g`.
+ * For example, the guard `g` might be a call `isSafe(x)` and the expression `e`
+ * the argument `x`.
+ */
+signature predicate guardChecksSig(IRGuardCondition g, Expr e, boolean branch);
+
+/**
+ * Provides a set of barrier nodes for a guard that validates an expression.
+ *
+ * This is expected to be used in `isBarrier`/`isSanitizer` definitions
+ * in data flow and taint tracking.
+ */
+module BarrierGuard<guardChecksSig/3 guardChecks> {
+  /** Gets a node that is safely guarded by the given guard check. */
+  ExprNode getABarrierNode() {
+    exists(IRGuardCondition g, ValueNumber value, boolean edge |
+      guardChecks(g, value.getAnInstruction().getConvertedResultExpression(), edge) and
+      result.asInstruction() = value.getAnInstruction() and
+      g.controls(result.asInstruction().getBlock(), edge)
+    )
+  }
+}
+
+/**
+ * Holds if the guard `g` validates the instruction `instr` upon evaluating to `branch`.
+ */
+signature predicate instructionGuardChecksSig(IRGuardCondition g, Instruction instr, boolean branch);
+
+/**
+ * Provides a set of barrier nodes for a guard that validates an instruction.
+ *
+ * This is expected to be used in `isBarrier`/`isSanitizer` definitions
+ * in data flow and taint tracking.
+ */
+module InstructionBarrierGuard<instructionGuardChecksSig/3 instructionGuardChecks> {
+  /** Gets a node that is safely guarded by the given guard check. */
+  ExprNode getABarrierNode() {
+    exists(IRGuardCondition g, ValueNumber value, boolean edge |
+      instructionGuardChecks(g, value.getAnInstruction(), edge) and
+      result.asInstruction() = value.getAnInstruction() and
+      g.controls(result.asInstruction().getBlock(), edge)
+    )
+  }
+}
+
+/**
+ * DEPRECATED: Use `BarrierGuard` module instead.
+ *
  * A guard that validates some instruction.
  *
  * To use this in a configuration, extend the class and provide a
@@ -1100,7 +1150,7 @@ class ContentSet instanceof Content {
  *
  * It is important that all extending classes in scope are disjoint.
  */
-class BarrierGuard extends IRGuardCondition {
+deprecated class BarrierGuard extends IRGuardCondition {
   /** Override this predicate to hold if this guard validates `instr` upon evaluating to `b`. */
   predicate checksInstr(Instruction instr, boolean b) { none() }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/PrintIRLocalFlow.qll

@@ -94,12 +94,6 @@ private string getNodeProperty(DataFlow::Node node, string key) {
       any(DataFlow::Configuration cfg).isBarrierIn(node) and kind = "in"
       or
       any(DataFlow::Configuration cfg).isBarrierOut(node) and kind = "out"
-      or
-      exists(DataFlow::BarrierGuard guard |
-        any(DataFlow::Configuration cfg).isBarrierGuard(guard) and
-        node = guard.getAGuardedNode() and
-        kind = "guard(" + guard.getResultId() + ")"
-      )
     |
       kind, ", "
     )

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/TaintTrackingUtil.qll

@@ -163,12 +163,6 @@ predicate defaultImplicitTaintRead(DataFlow::Node node, DataFlow::Content c) { n
  */
 predicate defaultTaintSanitizer(DataFlow::Node node) { none() }
 
-/**
- * Holds if `guard` should be a sanitizer guard in all global taint flow configurations
- * but not in local taint.
- */
-predicate defaultTaintSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
-
 /**
  * Holds if taint can flow from `instrIn` to `instrOut` through a call to a
  * modeled function.

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking1/TaintTrackingImpl.qll

@@ -116,20 +116,30 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
+   * Holds if taint propagation through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
-    this.isSanitizerGuard(guard) or defaultTaintSanitizerGuard(guard)
+  deprecated final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
   }
 
   /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
    * Holds if taint propagation through nodes guarded by `guard` is prohibited
    * when the flow state is `state`.
    */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) { none() }
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+    none()
+  }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+  deprecated final override predicate isBarrierGuard(
+    DataFlow::BarrierGuard guard, DataFlow::FlowState state
+  ) {
     this.isSanitizerGuard(guard, state)
   }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking2/TaintTrackingImpl.qll

@@ -116,20 +116,30 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
+   * Holds if taint propagation through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
-    this.isSanitizerGuard(guard) or defaultTaintSanitizerGuard(guard)
+  deprecated final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
   }
 
   /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
    * Holds if taint propagation through nodes guarded by `guard` is prohibited
    * when the flow state is `state`.
    */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) { none() }
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+    none()
+  }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+  deprecated final override predicate isBarrierGuard(
+    DataFlow::BarrierGuard guard, DataFlow::FlowState state
+  ) {
     this.isSanitizerGuard(guard, state)
   }
 

cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/tainttracking3/TaintTrackingImpl.qll

@@ -116,20 +116,30 @@ abstract class Configuration extends DataFlow::Configuration {
 
   final override predicate isBarrierOut(DataFlow::Node node) { this.isSanitizerOut(node) }
 
-  /** Holds if taint propagation through nodes guarded by `guard` is prohibited. */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
+  /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
+   * Holds if taint propagation through nodes guarded by `guard` is prohibited.
+   */
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard) { none() }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
-    this.isSanitizerGuard(guard) or defaultTaintSanitizerGuard(guard)
+  deprecated final override predicate isBarrierGuard(DataFlow::BarrierGuard guard) {
+    this.isSanitizerGuard(guard)
   }
 
   /**
+   * DEPRECATED: Use `isSanitizer` and `BarrierGuard` module instead.
+   *
    * Holds if taint propagation through nodes guarded by `guard` is prohibited
    * when the flow state is `state`.
    */
-  predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) { none() }
+  deprecated predicate isSanitizerGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+    none()
+  }
 
-  final override predicate isBarrierGuard(DataFlow::BarrierGuard guard, DataFlow::FlowState state) {
+  deprecated final override predicate isBarrierGuard(
+    DataFlow::BarrierGuard guard, DataFlow::FlowState state
+  ) {
     this.isSanitizerGuard(guard, state)
   }