Merge pull request github#18685 from paldepind/rust-future-content

Rust: Basic support for future content and `.await`

Author: paldepind

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

@@ -843,6 +843,15 @@ final class ElementContent extends Content, TElementContent {
   override Location getLocation() { result instanceof EmptyLocation }
 }
 
+/**
+ * A value that a future resolves to.
+ */
+final class FutureContent extends Content, TFutureContent {
+  override string toString() { result = "future" }
+
+  override Location getLocation() { result instanceof EmptyLocation }
+}
+
 /**
  * Content stored at a position in a tuple.
  *
@@ -1194,6 +1203,12 @@ module RustDataFlow implements InputSig<Location> {
         c instanceof FunctionCallReturnContent
       )
       or
+      exists(AwaitExprCfgNode await |
+        c instanceof FutureContent and
+        node1.asExpr() = await.getExpr() and
+        node2.asExpr() = await
+      )
+      or
       VariableCapture::readStep(node1, c, node2)
     )
     or
@@ -1553,7 +1568,8 @@ private module Cached {
         [
           any(IndexExprCfgNode i).getBase(), any(FieldExprCfgNode access).getExpr(),
           any(TryExprCfgNode try).getExpr(),
-          any(PrefixExprCfgNode pe | pe.getOperatorName() = "*").getExpr()
+          any(PrefixExprCfgNode pe | pe.getOperatorName() = "*").getExpr(),
+          any(AwaitExprCfgNode a).getExpr()
         ]
     } or
     TSsaNode(SsaImpl::DataFlowIntegration::SsaNode node) or
@@ -1609,6 +1625,7 @@ private module Cached {
     // TODO: Remove once library types are extracted
     TVariantInLibTupleFieldContent(VariantInLib::VariantInLib v, int pos) { pos = v.getAPosition() } or
     TElementContent() or
+    TFutureContent() or
     TTuplePositionContent(int pos) {
       pos in [0 .. max([
                 any(TuplePat pat).getNumberOfFields(),

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

@@ -102,6 +102,10 @@ module Input implements InputSig<Location, RustDataFlow> {
         c = TTuplePositionContent(pos) and
         arg = pos.toString()
       )
+      or
+      result = "Future" and
+      c = TFutureContent() and
+      arg = ""
     )
   }
 

rust/ql/test/library-tests/dataflow/models/main.rs

@@ -203,6 +203,17 @@ fn test_apply_flow_through() {
     sink(t); // $ hasValueFlow=33
 }
 
+// has a flow model with value flow from argument to returned future
+async fn get_async_number(a: i64) -> i64 {
+    37
+}
+
+async fn test_get_async_number() {
+    let s = source(46);
+    let t = get_async_number(s).await;
+    sink(t); // $ hasValueFlow=46
+}
+
 impl MyFieldEnum {
     // has a source model
     fn source(&self, i: i64) -> MyFieldEnum {
@@ -268,7 +279,8 @@ fn test_simple_sink() {
     simple_sink(s); // $ hasValueFlow=17
 }
 
-fn main() {
+#[tokio::main]
+async fn main() {
     test_identify();
     test_get_var_pos();
     test_set_var_pos();
@@ -286,5 +298,6 @@ fn main() {
     test_enum_method_sink();
     test_simple_source();
     test_simple_sink();
+    test_get_async_number().await;
     let dummy = Some(0); // ensure that the the `lang:core` crate is extracted
 }