Merge pull request #21922 from hvitved/rust/static-const-resolution

Rust: Path resolution for `static` items

Author: hvitved

rust/ql/.generated.list

@@ -99,6 +99,8 @@ class FormatTemplateVariableAccessTree extends LeafTree, FormatTemplateVariableA
 class ItemTree extends LeafTree, Item {
   ItemTree() {
     not this instanceof MacroCall and
+    not this instanceof Const and
+    not this instanceof Static and
     this = any(StmtList s).getAStatement()
   }
 }

rust/ql/.gitattributes

@@ -45,3 +45,14 @@ final class CallableScope extends CfgScopeImpl, Callable {
   /** Holds if `scope` is exited when `last` finishes with completion `c`. */
   override predicate scopeLast(AstNode last, Completion c) { last(this.getBody(), last, c) }
 }
+
+/**
+ * A special scope used to represent the context in which `const`s and
+ * `static`s are initialized. We do not actually compute a CFG for such
+ * scopes.
+ */
+final class SourceFileScope extends CfgScopeImpl, SourceFile {
+  override predicate scopeFirst(AstNode first) { none() }
+
+  override predicate scopeLast(AstNode last, Completion c) { none() }
+}

rust/ql/lib/codeql/rust/controlflow/internal/ControlFlowGraphImpl.qll

@@ -653,8 +653,22 @@ module RustDataFlowGen<RustDataFlowInputSig Input> implements InputSig<Location>
    */
   predicate jumpStep(Node node1, Node node2) {
     FlowSummaryImpl::Private::Steps::summaryJumpStep(node1.(FlowSummaryNode).getSummaryNode(),
-      node2.(FlowSummaryNode).getSummaryNode()) or
+      node2.(FlowSummaryNode).getSummaryNode())
+    or
     FlowSummaryImpl::Private::Steps::sourceJumpStep(node1.(FlowSummaryNode).getSummaryNode(), node2)
+    or
+    exists(Const c |
+      node1.asExpr() = c.getBody() and
+      node2.asExpr() = c.getAnAccess()
+    )
+    or
+    exists(StaticNode sn, Static s | s = sn.getStatic() |
+      node1 = sn and
+      node2.asExpr() = s.getAnAccess().(StaticReadAccess)
+      or
+      node1.asExpr() = [s.getBody(), s.getAnAccess().(StaticWriteAccess)] and
+      node2 = sn
+    )
   }
 
   pragma[nomagic]

rust/ql/lib/codeql/rust/controlflow/internal/Scope.qll

@@ -704,6 +704,17 @@ final class CastNode extends ExprNode {
   CastNode() { none() }
 }
 
+/**
+ * A node in the data flow graph that corresponds to a `static`.
+ */
+class StaticNode extends AstNodeNode, TStaticNode {
+  override Static n;
+
+  StaticNode() { this = TStaticNode(n) }
+
+  Static getStatic() { result = n }
+}
+
 cached
 newtype TNode =
   TExprNode(Expr e) { e.hasEnclosingCfgScope() and Stages::DataFlowStage::ref() } or
@@ -755,4 +766,5 @@ newtype TNode =
     )
   } or
   TClosureSelfReferenceNode(CfgScope c) { lambdaCreationExpr(c) } or
-  TCaptureNode(VariableCapture::Flow::SynthesizedCaptureNode cn)
+  TCaptureNode(VariableCapture::Flow::SynthesizedCaptureNode cn) or
+  TStaticNode(Static s)

rust/ql/lib/codeql/rust/dataflow/internal/DataFlowImpl.qll

@@ -0,0 +1,11 @@
+/**
+ * This module provides the public class `StaticAccess`.
+ */
+
+private import internal.StaticImpl
+
+final class StaticAccess = Impl::StaticAccess;
+
+final class StaticWriteAccess = Impl::StaticWriteAccess;
+
+final class StaticReadAccess = Impl::StaticReadAccess;

rust/ql/lib/codeql/rust/dataflow/internal/Node.qll

@@ -48,15 +48,29 @@ module Impl {
       )
     }
 
+    pragma[nomagic]
+    private predicate isConstOrStatic(File f) {
+      f = this.getFile() and
+      (
+        this instanceof Const
+        or
+        this instanceof Static
+      )
+    }
+
     /** Gets the CFG scope that encloses this node, if any. */
     cached
     CfgScope getEnclosingCfgScope() {
       exists(AstNode p | p = this.getParentNode() |
-        result = p
+        result = p and
+        not result instanceof SourceFile
         or
         not p instanceof CfgScope and
+        not this.isConstOrStatic(_) and
         result = p.getEnclosingCfgScope()
       )
+      or
+      this.isConstOrStatic(result.(SourceFile).getFile())
     }
 
     /** Holds if this node is inside a CFG scope. */

rust/ql/lib/codeql/rust/elements/StaticAccess.qll

@@ -24,7 +24,12 @@ module Impl {
    * const X: i32 = 42;
    * ```
    */
-  class Const extends Generated::Const { }
+  class Const extends Generated::Const {
+    /** Gets an access to this constant item. */
+    ConstAccess getAnAccess() { this = result.getConst() }
+
+    override string toStringImpl() { result = "const " + this.getName().getText() }
+  }
 
   /**
    * A constant access.

rust/ql/lib/codeql/rust/elements/internal/AstNodeImpl.qll

@@ -1,17 +1,21 @@
-// generated by codegen, remove this comment if you wish to edit this file
 /**
  * This module provides a hand-modifiable wrapper around the generated class `Static`.
  *
  * INTERNAL: Do not use.
  */
 
 private import codeql.rust.elements.internal.generated.Static
+private import codeql.rust.elements.internal.AstNodeImpl::Impl as AstNodeImpl
+private import codeql.rust.elements.internal.PathExprImpl::Impl as PathExprImpl
+private import codeql.rust.elements.internal.VariableImpl::Impl as VariableImpl
+private import codeql.rust.internal.PathResolution
 
 /**
  * INTERNAL: This module contains the customizable definition of `Static` and should not
  * be referenced directly.
  */
 module Impl {
+  // the following QLdoc is generated: if you need to edit it, do it in the schema file
   /**
    * A static item declaration.
    *
@@ -20,5 +24,43 @@ module Impl {
    * static X: i32 = 42;
    * ```
    */
-  class Static extends Generated::Static { }
+  class Static extends Generated::Static {
+    /** Gets an access to this static item. */
+    StaticAccess getAnAccess() { this = result.getStatic() }
+
+    override string toStringImpl() { result = "static " + this.getName().getText() }
+  }
+
+  /**
+   * A static access.
+   *
+   * For example:
+   * ```rust
+   * static X: i32 = 42;
+   *
+   * fn main() {
+   *     println!("{}", X);
+   * }
+   * ```
+   */
+  class StaticAccess extends AstNodeImpl::AstNode, PathExprImpl::PathExpr {
+    private Static s;
+
+    StaticAccess() { s = resolvePath(this.getPath()) }
+
+    /** Gets the static being accessed. */
+    Static getStatic() { result = s }
+
+    override string getAPrimaryQlClass() { result = "StaticAccess" }
+  }
+
+  /** A static write access. */
+  class StaticWriteAccess extends StaticAccess {
+    StaticWriteAccess() { VariableImpl::assignmentOperationDescendant(_, this) }
+  }
+
+  /** A static read access. */
+  class StaticReadAccess extends StaticAccess {
+    StaticReadAccess() { not this instanceof StaticWriteAccess }
+  }
 }