Merge pull request #22061 from MathiasVP/mad-write-through-model

Shared: Support flow summaries from `ReturnValue`s

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

@@ -6,6 +6,7 @@ private import cpp as Cpp
 private import codeql.dataflow.internal.FlowSummaryImpl
 private import codeql.dataflow.internal.AccessPathSyntax as AccessPath
 private import semmle.code.cpp.ir.dataflow.internal.DataFlowPrivate
+private import semmle.code.cpp.ir.dataflow.internal.DataFlowNodes
 private import semmle.code.cpp.ir.dataflow.internal.DataFlowUtil
 private import semmle.code.cpp.ir.dataflow.internal.DataFlowImplSpecific as DataFlowImplSpecific
 private import semmle.code.cpp.dataflow.ExternalFlow
@@ -20,8 +21,22 @@ module Input implements InputSig<Location, DataFlowImplSpecific::CppDataFlow> {
 
   class SinkBase = Void;
 
+  class FlowSummaryCallBase = CallInstruction;
+
   predicate callableFromSource(SummarizedCallableBase c) { exists(c.getBlock()) }
 
+  FlowSummaryCallBase getASourceCall(SummarizedCallableBase sc) {
+    result.getStaticCallTarget() = sc
+  }
+
+  DataFlowCallable getSummarizedCallableAsDataFlowCallable(SummarizedCallableBase c) {
+    result.asSummarizedCallable() = c
+  }
+
+  DataFlowCallable getSourceCallEnclosingCallable(FlowSummaryCallBase call) {
+    result.asSourceCallable() = call.getEnclosingFunction()
+  }
+
   ArgumentPosition callbackSelfParameterPosition() { result = TDirectPosition(-1) }
 
   ReturnKind getStandardReturnValueKind() { result = getReturnValueKind("") }
@@ -30,6 +45,10 @@ module Input implements InputSig<Location, DataFlowImplSpecific::CppDataFlow> {
     arg = repeatStars(result.(NormalReturnKind).getIndirectionIndex())
   }
 
+  ParameterPosition getFlowSummaryParameterPosition(ReturnKind rk) {
+    result = TFlowSummaryPosition(rk)
+  }
+
   string encodeParameterPosition(ParameterPosition pos) { result = pos.toString() }
 
   string encodeArgumentPosition(ArgumentPosition pos) { result = pos.toString() }
@@ -114,10 +133,22 @@ module Input implements InputSig<Location, DataFlowImplSpecific::CppDataFlow> {
 private import Make<Location, DataFlowImplSpecific::CppDataFlow, Input> as Impl
 
 private module StepsInput implements Impl::Private::StepsInputSig {
+  Impl::Private::SummaryNode getSummaryNode(Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   DataFlowCall getACall(Public::SummarizedCallable sc) {
     result.getStaticCallTarget().getUnderlyingCallable() = sc
   }
 
+  Node getSourceOutNode(Input::FlowSummaryCallBase call, ReturnKind rk) {
+    exists(IndirectReturnOutNode out | result = out |
+      out.getCallInstruction() = call and
+      pragma[only_bind_out](rk.(NormalReturnKind).getIndirectionIndex()) =
+        pragma[only_bind_out](out.getIndirectionIndex())
+    )
+  }
+
   DataFlowCallable getSourceNodeEnclosingCallable(Input::SourceBase source) { none() }
 
   Node getSourceNode(Input::SourceBase source, Impl::Private::SummaryComponentStack s) { none() }

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

@@ -1534,12 +1534,8 @@ class FlowSummaryNode extends Node, TFlowSummaryNode {
     result = this.getSummaryNode().getSummarizedCallable()
   }
 
-  /**
-   * Gets the enclosing callable. For a `FlowSummaryNode` this is always the
-   * summarized function this node is part of.
-   */
   override DataFlowCallable getEnclosingCallable() {
-    result.asSummarizedCallable() = this.getSummarizedCallable()
+    result = FlowSummaryImpl::Private::getEnclosingCallable(this.getSummaryNode())
   }
 
   override Location getLocationImpl() { result = this.getSummarizedCallable().getLocation() }

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

@@ -561,6 +561,21 @@ class SummaryArgumentNode extends ArgumentNode, FlowSummaryNode {
   }
 }
 
+/** An argument node that re-enters return output as input to a flow summary. */
+private class FlowSummaryArgumentNode extends ArgumentNode, FlowSummaryNode {
+  private CallInstruction callInstruction;
+  private ReturnKind rk;
+
+  FlowSummaryArgumentNode() {
+    this.getSummaryNode() = FlowSummaryImpl::Private::summaryArgumentNode(callInstruction, rk)
+  }
+
+  override predicate argumentOf(DataFlowCall call, ArgumentPosition pos) {
+    call.asCallInstruction() = callInstruction and
+    pos = TFlowSummaryPosition(rk)
+  }
+}
+
 /** A parameter position represented by an integer. */
 class ParameterPosition = Position;
 
@@ -616,6 +631,18 @@ class IndirectionPosition extends Position, TIndirectionPosition {
   final override int getIndirectionIndex() { result = indirectionIndex }
 }
 
+class FlowSummaryPosition extends Position, TFlowSummaryPosition {
+  ReturnKind rk;
+
+  FlowSummaryPosition() { this = TFlowSummaryPosition(rk) }
+
+  override string toString() { result = "write to: " + rk.toString() }
+
+  override int getArgumentIndex() { none() }
+
+  final override int getIndirectionIndex() { result = rk.getIndirectionIndex() }
+}
+
 newtype TPosition =
   TDirectPosition(int argumentIndex) {
     exists(any(CallInstruction c).getArgument(argumentIndex))
@@ -634,7 +661,8 @@ newtype TPosition =
       p = f.getParameter(argumentIndex) and
       indirectionIndex = [1 .. Ssa::getMaxIndirectionsForType(p.getUnspecifiedType()) - 1]
     )
-  }
+  } or
+  TFlowSummaryPosition(ReturnKind rk) { FlowSummaryImpl::Private::relevantFlowSummaryPosition(rk) }
 
 private newtype TReturnKind =
   TNormalReturnKind(int indirectionIndex) {

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

@@ -158,7 +158,7 @@ private module Cached {
     model = ""
     or
     // models-as-data summarized flow
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
       nodeTo.(FlowSummaryNode).getSummaryNode(), true, model)
   }
 

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

@@ -67,7 +67,7 @@ private module Cached {
     model = ""
     or
     // models-as-data summarized flow
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
       nodeTo.(FlowSummaryNode).getSummaryNode(), false, model)
     or
     // object->field conflation for content that is a `TaintInheritingContent`.

cpp/ql/test/library-tests/dataflow/external-models/flow.expected

@@ -53,14 +53,17 @@ models
 | 52 | Summary: ; ; false; ymlStepGenerated; ; ; Argument[0]; ReturnValue; taint; df-generated |
 | 53 | Summary: ; ; false; ymlStepManual; ; ; Argument[0]; ReturnValue; taint; manual |
 | 54 | Summary: ; ; false; ymlStepManual_with_body; ; ; Argument[0]; ReturnValue; taint; manual |
-| 55 | Summary: ; TemplateClass1; true; templateFunction2<U,V>; (U,V); ; Argument[1]; ReturnValue; value; manual |
-| 56 | Summary: ; TemplateClass1<T>; false; templateFunction<U>; (T,U); ; Argument[0]; ReturnValue; value; manual |
-| 57 | Summary: ; TemplateClass2<T,U>; true; function; (U,T); ; Argument[1]; ReturnValue; value; manual |
-| 58 | Summary: Azure::Core::IO; BodyStream; true; Read; ; ; Argument[-1]; Argument[*0]; taint; manual |
-| 59 | Summary: Azure::Core::IO; BodyStream; true; ReadToCount; ; ; Argument[-1]; Argument[*0]; taint; manual |
-| 60 | Summary: Azure::Core::IO; BodyStream; true; ReadToEnd; ; ; Argument[-1]; ReturnValue.Element; taint; manual |
-| 61 | Summary: Azure; Nullable; true; Value; ; ; Argument[-1]; ReturnValue[*]; taint; manual |
-| 62 | Summary: boost::asio; ; false; buffer; ; ; Argument[*0]; ReturnValue; taint; manual |
+| 55 | Summary: ; MyString; true; operator[]; ; ; Argument[-1]; ReturnValue[*]; taint; manual |
+| 56 | Summary: ; MyString; true; operator[]; ; ; ReturnValue[*]; Argument[-1]; taint; manual |
+| 57 | Summary: ; ReverseFlow; true; get_ptr; ; ; ReturnValue[*]; Argument[-1].Field[ReverseFlow::value]; value; manual |
+| 58 | Summary: ; TemplateClass1; true; templateFunction2<U,V>; (U,V); ; Argument[1]; ReturnValue; value; manual |
+| 59 | Summary: ; TemplateClass1<T>; false; templateFunction<U>; (T,U); ; Argument[0]; ReturnValue; value; manual |
+| 60 | Summary: ; TemplateClass2<T,U>; true; function; (U,T); ; Argument[1]; ReturnValue; value; manual |
+| 61 | Summary: Azure::Core::IO; BodyStream; true; Read; ; ; Argument[-1]; Argument[*0]; taint; manual |
+| 62 | Summary: Azure::Core::IO; BodyStream; true; ReadToCount; ; ; Argument[-1]; Argument[*0]; taint; manual |
+| 63 | Summary: Azure::Core::IO; BodyStream; true; ReadToEnd; ; ; Argument[-1]; ReturnValue.Element; taint; manual |
+| 64 | Summary: Azure; Nullable; true; Value; ; ; Argument[-1]; ReturnValue[*]; taint; manual |
+| 65 | Summary: boost::asio; ; false; buffer; ; ; Argument[*0]; ReturnValue; taint; manual |
 edges
 | asio_streams.cpp:87:34:87:44 | read_until output argument | asio_streams.cpp:91:7:91:17 | recv_buffer | provenance | Src:MaD:32  |
 | asio_streams.cpp:87:34:87:44 | read_until output argument | asio_streams.cpp:93:29:93:39 | *recv_buffer | provenance | Src:MaD:32 Sink:MaD:2 |
@@ -69,16 +72,16 @@ edges
 | asio_streams.cpp:100:44:100:62 | call to buffer | asio_streams.cpp:100:44:100:62 | call to buffer | provenance |  |
 | asio_streams.cpp:100:44:100:62 | call to buffer | asio_streams.cpp:101:7:101:17 | send_buffer | provenance |  |
 | asio_streams.cpp:100:44:100:62 | call to buffer | asio_streams.cpp:103:29:103:39 | *send_buffer | provenance | Sink:MaD:2 |
-| asio_streams.cpp:100:64:100:71 | *send_str | asio_streams.cpp:100:44:100:62 | call to buffer | provenance | MaD:62 |
+| asio_streams.cpp:100:64:100:71 | *send_str | asio_streams.cpp:100:44:100:62 | call to buffer | provenance | MaD:65 |
 | azure.cpp:253:48:253:60 | *call to GetBodyStream | azure.cpp:253:48:253:60 | *call to GetBodyStream | provenance | Src:MaD:29  |
 | azure.cpp:253:48:253:60 | *call to GetBodyStream | azure.cpp:257:5:257:8 | *resp | provenance |  |
 | azure.cpp:253:48:253:60 | *call to GetBodyStream | azure.cpp:262:5:262:8 | *resp | provenance |  |
 | azure.cpp:253:48:253:60 | *call to GetBodyStream | azure.cpp:266:38:266:41 | *resp | provenance |  |
-| azure.cpp:257:5:257:8 | *resp | azure.cpp:257:16:257:21 | Read output argument | provenance | MaD:58 |
+| azure.cpp:257:5:257:8 | *resp | azure.cpp:257:16:257:21 | Read output argument | provenance | MaD:61 |
 | azure.cpp:257:16:257:21 | Read output argument | azure.cpp:258:10:258:16 | * ... | provenance |  |
-| azure.cpp:262:5:262:8 | *resp | azure.cpp:262:23:262:28 | ReadToCount output argument | provenance | MaD:59 |
+| azure.cpp:262:5:262:8 | *resp | azure.cpp:262:23:262:28 | ReadToCount output argument | provenance | MaD:62 |
 | azure.cpp:262:23:262:28 | ReadToCount output argument | azure.cpp:263:10:263:16 | * ... | provenance |  |
-| azure.cpp:266:38:266:41 | *resp | azure.cpp:266:44:266:52 | call to ReadToEnd [element] | provenance | MaD:60 |
+| azure.cpp:266:38:266:41 | *resp | azure.cpp:266:44:266:52 | call to ReadToEnd [element] | provenance | MaD:63 |
 | azure.cpp:266:44:266:52 | call to ReadToEnd [element] | azure.cpp:266:44:266:52 | call to ReadToEnd [element] | provenance |  |
 | azure.cpp:266:44:266:52 | call to ReadToEnd [element] | azure.cpp:267:10:267:12 | vec [element] | provenance |  |
 | azure.cpp:267:10:267:12 | vec [element] | azure.cpp:267:10:267:12 | vec | provenance |  |
@@ -94,10 +97,10 @@ edges
 | azure.cpp:278:10:278:13 | body | azure.cpp:278:10:278:13 | body | provenance |  |
 | azure.cpp:281:68:281:84 | *call to ExtractBodyStream | azure.cpp:281:68:281:84 | *call to ExtractBodyStream | provenance | Src:MaD:26  |
 | azure.cpp:281:68:281:84 | *call to ExtractBodyStream | azure.cpp:282:21:282:23 | *call to get | provenance |  |
-| azure.cpp:282:21:282:23 | *call to get | azure.cpp:282:28:282:36 | call to ReadToEnd [element] | provenance | MaD:60 |
+| azure.cpp:282:21:282:23 | *call to get | azure.cpp:282:28:282:36 | call to ReadToEnd [element] | provenance | MaD:63 |
 | azure.cpp:282:28:282:36 | call to ReadToEnd [element] | azure.cpp:282:10:282:38 | call to ReadToEnd | provenance |  |
 | azure.cpp:282:28:282:36 | call to ReadToEnd [element] | azure.cpp:282:28:282:36 | call to ReadToEnd [element] | provenance |  |
-| azure.cpp:289:24:289:56 | call to GetHeader | azure.cpp:289:63:289:65 | call to Value | provenance | MaD:61 |
+| azure.cpp:289:24:289:56 | call to GetHeader | azure.cpp:289:63:289:65 | call to Value | provenance | MaD:64 |
 | azure.cpp:289:32:289:40 | call to GetHeader | azure.cpp:289:24:289:56 | call to GetHeader | provenance |  |
 | azure.cpp:289:32:289:40 | call to GetHeader | azure.cpp:289:32:289:40 | call to GetHeader | provenance | Src:MaD:30  |
 | azure.cpp:289:63:289:65 | call to Value | azure.cpp:289:63:289:65 | call to Value | provenance |  |
@@ -159,27 +162,27 @@ edges
 | test.cpp:133:10:133:18 | call to ymlSource | test.cpp:134:45:134:45 | x | provenance |  |
 | test.cpp:134:13:134:43 | call to templateFunction | test.cpp:134:13:134:43 | call to templateFunction | provenance |  |
 | test.cpp:134:13:134:43 | call to templateFunction | test.cpp:135:10:135:10 | y | provenance | Sink:MaD:1 |
-| test.cpp:134:45:134:45 | x | test.cpp:134:13:134:43 | call to templateFunction | provenance | MaD:56 |
+| test.cpp:134:45:134:45 | x | test.cpp:134:13:134:43 | call to templateFunction | provenance | MaD:59 |
 | test.cpp:146:10:146:18 | call to ymlSource | test.cpp:146:10:146:18 | call to ymlSource | provenance | Src:MaD:25  |
 | test.cpp:146:10:146:18 | call to ymlSource | test.cpp:148:26:148:26 | x | provenance |  |
 | test.cpp:148:10:148:27 | call to function | test.cpp:148:10:148:27 | call to function | provenance |  |
 | test.cpp:148:10:148:27 | call to function | test.cpp:149:10:149:10 | z | provenance | Sink:MaD:1 |
-| test.cpp:148:26:148:26 | x | test.cpp:148:10:148:27 | call to function | provenance | MaD:57 |
+| test.cpp:148:26:148:26 | x | test.cpp:148:10:148:27 | call to function | provenance | MaD:60 |
 | test.cpp:155:10:155:18 | call to ymlSource | test.cpp:155:10:155:18 | call to ymlSource | provenance | Src:MaD:25  |
 | test.cpp:155:10:155:18 | call to ymlSource | test.cpp:157:26:157:26 | x | provenance |  |
 | test.cpp:157:13:157:20 | call to function | test.cpp:157:13:157:20 | call to function | provenance |  |
 | test.cpp:157:13:157:20 | call to function | test.cpp:158:10:158:10 | z | provenance | Sink:MaD:1 |
-| test.cpp:157:26:157:26 | x | test.cpp:157:13:157:20 | call to function | provenance | MaD:57 |
+| test.cpp:157:26:157:26 | x | test.cpp:157:13:157:20 | call to function | provenance | MaD:60 |
 | test.cpp:164:34:164:34 | x | test.cpp:165:69:165:69 | x | provenance |  |
 | test.cpp:165:12:165:64 | call to templateFunction2 | test.cpp:164:7:164:7 | *templateFunction3 | provenance |  |
 | test.cpp:165:12:165:64 | call to templateFunction2 | test.cpp:165:12:165:64 | call to templateFunction2 | provenance |  |
-| test.cpp:165:69:165:69 | x | test.cpp:165:12:165:64 | call to templateFunction2 | provenance | MaD:55 |
+| test.cpp:165:69:165:69 | x | test.cpp:165:12:165:64 | call to templateFunction2 | provenance | MaD:58 |
 | test.cpp:170:10:170:18 | call to ymlSource | test.cpp:170:10:170:18 | call to ymlSource | provenance | Src:MaD:25  |
 | test.cpp:170:10:170:18 | call to ymlSource | test.cpp:172:51:172:51 | x | provenance |  |
 | test.cpp:172:13:172:44 | call to templateFunction3 | test.cpp:172:13:172:44 | call to templateFunction3 | provenance |  |
 | test.cpp:172:13:172:44 | call to templateFunction3 | test.cpp:173:10:173:10 | y | provenance | Sink:MaD:1 |
 | test.cpp:172:51:172:51 | x | test.cpp:164:34:164:34 | x | provenance |  |
-| test.cpp:172:51:172:51 | x | test.cpp:172:13:172:44 | call to templateFunction3 | provenance | MaD:55 |
+| test.cpp:172:51:172:51 | x | test.cpp:172:13:172:44 | call to templateFunction3 | provenance | MaD:58 |
 | test.cpp:186:2:186:2 | *s [post update] [myField] | test.cpp:187:33:187:34 | *& ... [myField] | provenance |  |
 | test.cpp:186:2:186:24 | ... = ... | test.cpp:186:2:186:2 | *s [post update] [myField] | provenance |  |
 | test.cpp:186:14:186:22 | call to ymlSource | test.cpp:186:2:186:24 | ... = ... | provenance | Src:MaD:25  |
@@ -192,6 +195,18 @@ edges
 | test.cpp:200:10:200:33 | call to read_field_from_struct_2 | test.cpp:200:10:200:33 | call to read_field_from_struct_2 | provenance |  |
 | test.cpp:200:10:200:33 | call to read_field_from_struct_2 | test.cpp:201:10:201:10 | x | provenance | Sink:MaD:1 |
 | test.cpp:200:35:200:36 | *& ... [myField] | test.cpp:200:10:200:33 | call to read_field_from_struct_2 | provenance | MaD:51 |
+| test.cpp:216:3:216:4 | get_ptr output argument [value] | test.cpp:217:11:217:12 | *rf [value] | provenance |  |
+| test.cpp:216:3:216:28 | ... = ... | test.cpp:216:3:216:4 | get_ptr output argument [value] | provenance | MaD:57 |
+| test.cpp:216:18:216:26 | call to ymlSource | test.cpp:216:3:216:28 | ... = ... | provenance | Src:MaD:25  |
+| test.cpp:217:11:217:12 | *rf [value] | test.cpp:217:14:217:18 | value | provenance |  |
+| test.cpp:217:14:217:18 | value | test.cpp:217:14:217:18 | value | provenance |  |
+| test.cpp:217:14:217:18 | value | test.cpp:218:11:218:11 | x | provenance | Sink:MaD:1 |
+| test.cpp:222:3:222:3 | operator[] output argument | test.cpp:223:12:223:12 | *s | provenance |  |
+| test.cpp:222:3:222:20 | ... = ... | test.cpp:222:3:222:3 | operator[] output argument | provenance | MaD:56 |
+| test.cpp:222:10:222:20 | call to ymlSource | test.cpp:222:3:222:20 | ... = ... | provenance | Src:MaD:25  |
+| test.cpp:223:12:223:12 | *s | test.cpp:223:13:223:15 | call to operator[] | provenance | MaD:55 |
+| test.cpp:223:13:223:15 | call to operator[] | test.cpp:223:13:223:15 | call to operator[] | provenance |  |
+| test.cpp:223:13:223:15 | call to operator[] | test.cpp:224:11:224:11 | c | provenance | Sink:MaD:1 |
 | windows.cpp:22:15:22:29 | *call to GetCommandLineA | windows.cpp:22:15:22:29 | *call to GetCommandLineA | provenance | Src:MaD:3  |
 | windows.cpp:22:15:22:29 | *call to GetCommandLineA | windows.cpp:24:8:24:11 | * ... | provenance |  |
 | windows.cpp:22:15:22:29 | *call to GetCommandLineA | windows.cpp:27:36:27:38 | *cmd | provenance |  |
@@ -470,6 +485,20 @@ nodes
 | test.cpp:200:10:200:33 | call to read_field_from_struct_2 | semmle.label | call to read_field_from_struct_2 |
 | test.cpp:200:35:200:36 | *& ... [myField] | semmle.label | *& ... [myField] |
 | test.cpp:201:10:201:10 | x | semmle.label | x |
+| test.cpp:216:3:216:4 | get_ptr output argument [value] | semmle.label | get_ptr output argument [value] |
+| test.cpp:216:3:216:28 | ... = ... | semmle.label | ... = ... |
+| test.cpp:216:18:216:26 | call to ymlSource | semmle.label | call to ymlSource |
+| test.cpp:217:11:217:12 | *rf [value] | semmle.label | *rf [value] |
+| test.cpp:217:14:217:18 | value | semmle.label | value |
+| test.cpp:217:14:217:18 | value | semmle.label | value |
+| test.cpp:218:11:218:11 | x | semmle.label | x |
+| test.cpp:222:3:222:3 | operator[] output argument | semmle.label | operator[] output argument |
+| test.cpp:222:3:222:20 | ... = ... | semmle.label | ... = ... |
+| test.cpp:222:10:222:20 | call to ymlSource | semmle.label | call to ymlSource |
+| test.cpp:223:12:223:12 | *s | semmle.label | *s |
+| test.cpp:223:13:223:15 | call to operator[] | semmle.label | call to operator[] |
+| test.cpp:223:13:223:15 | call to operator[] | semmle.label | call to operator[] |
+| test.cpp:224:11:224:11 | c | semmle.label | c |
 | windows.cpp:22:15:22:29 | *call to GetCommandLineA | semmle.label | *call to GetCommandLineA |
 | windows.cpp:22:15:22:29 | *call to GetCommandLineA | semmle.label | *call to GetCommandLineA |
 | windows.cpp:24:8:24:11 | * ... | semmle.label | * ... |

cpp/ql/test/library-tests/dataflow/external-models/flow.ext.yml

@@ -23,4 +23,7 @@ extensions:
       - ["", "TemplateClass1", True, "templateFunction2<U,V>", "(U,V)", "", "Argument[1]", "ReturnValue", "value", "manual"]
       - ["", "TemplateClass2<T,U>", True, "function", "(U,T)", "", "Argument[1]", "ReturnValue", "value", "manual"]
       - ["", "", False, "read_field_from_struct", "", "", "Argument[*0].Field[MyNamespace::MyStructInNamespace::myField]", "ReturnValue", "value", "manual"]
-      - ["", "", False, "read_field_from_struct_2", "", "", "Argument[*0].Field[MyGlobalStruct::myField]", "ReturnValue", "value", "manual"]
+      - ["", "", False, "read_field_from_struct_2", "", "", "Argument[*0].Field[MyGlobalStruct::myField]", "ReturnValue", "value", "manual"]
+      - ["", "ReverseFlow", True, "get_ptr", "", "", "ReturnValue[*]", "Argument[-1].Field[ReverseFlow::value]", "value", "manual"]
+      - ["", "MyString", True, "operator[]", "", "", "ReturnValue[*]", "Argument[-1]", "taint", "manual"]
+      - ["", "MyString", True, "operator[]", "", "", "Argument[-1]", "ReturnValue[*]", "taint", "manual"]

cpp/ql/test/library-tests/dataflow/external-models/sinks.expected

@@ -21,3 +21,5 @@
 | test.cpp:173:10:173:10 | y | test-sink |
 | test.cpp:188:10:188:10 | x | test-sink |
 | test.cpp:201:10:201:10 | x | test-sink |
+| test.cpp:218:11:218:11 | x | test-sink |
+| test.cpp:224:11:224:11 | c | test-sink |

cpp/ql/test/library-tests/dataflow/external-models/sources.expected

@@ -15,6 +15,8 @@
 | test.cpp:170:10:170:18 | call to ymlSource | local |
 | test.cpp:186:14:186:22 | call to ymlSource | local |
 | test.cpp:199:14:199:22 | call to ymlSource | local |
+| test.cpp:216:18:216:26 | call to ymlSource | local |
+| test.cpp:222:10:222:20 | call to ymlSource | local |
 | windows.cpp:22:15:22:29 | *call to GetCommandLineA | local |
 | windows.cpp:34:17:34:38 | *call to GetEnvironmentStringsA | local |
 | windows.cpp:39:36:39:38 | GetEnvironmentVariableA output argument | local |

cpp/ql/test/library-tests/dataflow/external-models/test.cpp

@@ -199,4 +199,28 @@ void test_fully_qualified_field_test_2() {
 	s.myField = ymlSource();
 	int x = read_field_from_struct_2(&s);
 	ymlSink(x); // $ ir
+}
+
+struct ReverseFlow {
+	int value;
+	int& get_ptr();
+};
+
+struct MyString {
+	char& operator[](unsigned);
+};
+
+void test_reverse_flow(unsigned i, unsigned j) {
+	{
+		ReverseFlow rf;
+		rf.get_ptr() = ymlSource();
+		int x = rf.value;
+		ymlSink(x); // $ ir
+	}
+	{
+		MyString s;
+		s[i] = ymlSource();
+		char c = s[j];
+		ymlSink(c); // $ ir
+	}
 }

csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -714,7 +714,7 @@ predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo, string model) {
   ) and
   model = ""
   or
-  FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+  FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
     nodeTo.(FlowSummaryNode).getSummaryNode(), true, model)
 }
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/FlowSummaryImpl.qll

@@ -34,6 +34,8 @@ module Input implements InputSig<Location, DataFlowImplSpecific::CsharpDataFlow>
 
   class SinkBase = Void;
 
+  class FlowSummaryCallBase = Void;
+
   predicate neutralElement(SummarizedCallableBase c, string kind, string provenance, boolean isExact) {
     interpretNeutral(c, kind, provenance, isExact)
   }
@@ -201,6 +203,10 @@ private module TypesInput implements Impl::Private::TypesInputSig {
 }
 
 private module StepsInput implements Impl::Private::StepsInputSig {
+  Impl::Private::SummaryNode getSummaryNode(Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   DataFlowCall getACall(Public::SummarizedCallable sc) {
     sc = viableCallable(result).asSummarizedCallable()
   }

csharp/ql/lib/semmle/code/csharp/dataflow/internal/TaintTrackingPrivate.qll

@@ -171,7 +171,7 @@ private module Cached {
     ) and
     model = ""
     or
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
       nodeTo.(FlowSummaryNode).getSummaryNode(), false, model)
   }
 }

go/ql/lib/semmle/go/dataflow/internal/DataFlowUtil.qll

@@ -141,7 +141,7 @@ predicate simpleLocalFlowStep(Node nodeFrom, Node nodeTo, string model) {
   any(FunctionModel m).flowStep(nodeFrom, nodeTo) and
   model = "FunctionModel"
   or
-  FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+  FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
     nodeTo.(FlowSummaryNode).getSummaryNode(), true, model)
 }
 

go/ql/lib/semmle/go/dataflow/internal/FlowSummaryImpl.qll

@@ -31,6 +31,8 @@ module Input implements InputSig<Location, DataFlowImplSpecific::GoDataFlow> {
 
   class SinkBase = Void;
 
+  class FlowSummaryCallBase = Void;
+
   predicate callableFromSource(SummarizedCallableBase c) { exists(c.getFuncDef()) }
 
   predicate neutralElement(
@@ -113,6 +115,10 @@ module Input implements InputSig<Location, DataFlowImplSpecific::GoDataFlow> {
 private import Make<Location, DataFlowImplSpecific::GoDataFlow, Input> as Impl
 
 private module StepsInput implements Impl::Private::StepsInputSig {
+  Impl::Private::SummaryNode getSummaryNode(Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   DataFlowCall getACall(Public::SummarizedCallable sc) {
     exists(DataFlow::CallNode call |
       call.asExpr() = result and

go/ql/lib/semmle/go/dataflow/internal/TaintTrackingUtil.qll

@@ -109,8 +109,8 @@ private predicate localAdditionalForwardTaintStep(
   or
   any(AdditionalTaintStep a).step(pred, succ) and model = "AdditionalTaintStep"
   or
-  FlowSummaryImpl::Private::Steps::summaryLocalStep(pred.(DataFlowPrivate::FlowSummaryNode)
-        .getSummaryNode(), succ.(DataFlowPrivate::FlowSummaryNode).getSummaryNode(), false, model)
+  FlowSummaryImpl::Private::Steps::summaryLocalStep(pred,
+    succ.(DataFlowPrivate::FlowSummaryNode).getSummaryNode(), false, model)
 }
 
 /**

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

@@ -247,8 +247,8 @@ private predicate simpleLocalFlowStep0(Node node1, Node node2, string model) {
   or
   cloneStep(node1, node2) and model = "CloneStep"
   or
-  FlowSummaryImpl::Private::Steps::summaryLocalStep(node1.(FlowSummaryNode).getSummaryNode(),
-    node2.(FlowSummaryNode).getSummaryNode(), true, model)
+  FlowSummaryImpl::Private::Steps::summaryLocalStep(node1, node2.(FlowSummaryNode).getSummaryNode(),
+    true, model)
 }
 
 /**

java/ql/lib/semmle/code/java/dataflow/internal/FlowSummaryImpl.qll

@@ -41,6 +41,8 @@ module Input implements InputSig<Location, DataFlowImplSpecific::JavaDataFlow> {
 
   class SinkBase = Void;
 
+  class FlowSummaryCallBase = Void;
+
   predicate neutralElement(
     Input::SummarizedCallableBase c, string kind, string provenance, boolean isExact
   ) {
@@ -144,6 +146,10 @@ private module TypesInput implements Impl::Private::TypesInputSig {
 }
 
 private module StepsInput implements Impl::Private::StepsInputSig {
+  Impl::Private::SummaryNode getSummaryNode(Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   DataFlowCall getACall(Public::SummarizedCallable sc) {
     sc = viableCallable(result).asSummarizedCallable()
   }

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

@@ -145,8 +145,8 @@ private module Cached {
       )
     )
     or
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(src.(DataFlowPrivate::FlowSummaryNode)
-          .getSummaryNode(), sink.(DataFlowPrivate::FlowSummaryNode).getSummaryNode(), false, model)
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(src,
+      sink.(DataFlowPrivate::FlowSummaryNode).getSummaryNode(), false, model)
   }
 
   /**

java/ql/test/library-tests/dataflow/local-additional-taint/localAdditionalTaintStep.ql

@@ -13,8 +13,7 @@ predicate taintFlowUpdate(DataFlow::ParameterNode p1, DataFlow::ParameterNode p2
 }
 
 predicate summaryStep(FlowSummaryNode src, FlowSummaryNode sink) {
-  FlowSummaryImpl::Private::Steps::summaryLocalStep(src.getSummaryNode(), sink.getSummaryNode(),
-    false, _) or
+  FlowSummaryImpl::Private::Steps::summaryLocalStep(src, sink.getSummaryNode(), false, _) or
   FlowSummaryImpl::Private::Steps::summaryReadStep(src.getSummaryNode(), _, sink.getSummaryNode()) or
   FlowSummaryImpl::Private::Steps::summaryStoreStep(src.getSummaryNode(), _, sink.getSummaryNode())
 }

javascript/ql/lib/semmle/javascript/dataflow/internal/DataFlowPrivate.qll

@@ -1212,8 +1212,8 @@ private predicate valuePreservingStep(Node node1, Node node2) {
   or
   node2 = FlowSteps::getThrowTarget(node1)
   or
-  FlowSummaryPrivate::Steps::summaryLocalStep(node1.(FlowSummaryNode).getSummaryNode(),
-    node2.(FlowSummaryNode).getSummaryNode(), true, _) // TODO: preserve 'model'
+  FlowSummaryPrivate::Steps::summaryLocalStep(node1, node2.(FlowSummaryNode).getSummaryNode(), true,
+    _) // TODO: preserve 'model'
 }
 
 predicate knownSourceModel(Node sink, string model) { none() }

javascript/ql/lib/semmle/javascript/dataflow/internal/FlowSummaryPrivate.qll

@@ -142,6 +142,10 @@ string encodeArgumentPosition(ArgumentPosition pos) {
 ReturnKind getStandardReturnValueKind() { result = MkNormalReturnKind() and Stage::ref() }
 
 private module FlowSummaryStepInput implements Private::StepsInputSig {
+  Private::SummaryNode getSummaryNode(DataFlow::Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   overlay[global]
   DataFlowCall getACall(SummarizedCallable sc) {
     exists(LibraryCallable callable | callable = sc |

javascript/ql/lib/semmle/javascript/dataflow/internal/TaintTrackingPrivate.qll

@@ -12,8 +12,8 @@ cached
 predicate defaultAdditionalTaintStep(DataFlow::Node node1, DataFlow::Node node2) {
   TaintTracking::AdditionalTaintStep::step(node1, node2)
   or
-  FlowSummaryPrivate::Steps::summaryLocalStep(node1.(FlowSummaryNode).getSummaryNode(),
-    node2.(FlowSummaryNode).getSummaryNode(), false, _) // TODO: preserve 'model' parameter
+  FlowSummaryPrivate::Steps::summaryLocalStep(node1, node2.(FlowSummaryNode).getSummaryNode(),
+    false, _) // TODO: preserve 'model' parameter
   or
   // Convert steps out of array elements to plain taint steps
   FlowSummaryPrivate::Steps::summaryReadStep(node1.(FlowSummaryNode).getSummaryNode(),

javascript/ql/lib/semmle/javascript/dataflow/internal/sharedlib/DataFlowArg.qll

@@ -3,6 +3,7 @@ private import DataFlowImplSpecific
 private import codeql.dataflow.DataFlow as SharedDataFlow
 private import codeql.dataflow.TaintTracking as SharedTaintTracking
 private import codeql.dataflow.internal.FlowSummaryImpl as FlowSummaryImpl
+private import codeql.util.Void
 
 module JSDataFlow implements SharedDataFlow::InputSig<Location> {
   import Private
@@ -28,6 +29,8 @@ module JSFlowSummary implements FlowSummaryImpl::InputSig<Location, JSDataFlow>
   private import semmle.javascript.dataflow.internal.FlowSummaryPrivate as FlowSummaryPrivate
   import FlowSummaryPrivate
 
+  class FlowSummaryCallBase = Void;
+
   overlay[local]
   predicate callableFromSource(SummarizedCallableBase c) { none() }
 

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPrivate.qll

@@ -529,7 +529,7 @@ predicate simpleLocalFlowStepForTypetracking(Node nodeFrom, Node nodeTo) {
 }
 
 private predicate summaryLocalStep(Node nodeFrom, Node nodeTo, string model) {
-  FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+  FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
     nodeTo.(FlowSummaryNode).getSummaryNode(), true, model)
 }
 

python/ql/lib/semmle/python/dataflow/new/internal/FlowSummaryImpl.qll

@@ -20,6 +20,8 @@ module Input implements InputSig<Location, DataFlowImplSpecific::PythonDataFlow>
 
   class SinkBase = Void;
 
+  class FlowSummaryCallBase = Void;
+
   predicate callableFromSource(SummarizedCallableBase c) { none() }
 
   ArgumentPosition callbackSelfParameterPosition() { result.isLambdaSelf() }
@@ -111,6 +113,10 @@ module Input implements InputSig<Location, DataFlowImplSpecific::PythonDataFlow>
 private import Make<Location, DataFlowImplSpecific::PythonDataFlow, Input> as Impl
 
 private module StepsInput implements Impl::Private::StepsInputSig {
+  Impl::Private::SummaryNode getSummaryNode(Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   overlay[global]
   DataFlowCall getACall(Public::SummarizedCallable sc) {
     result =

python/ql/lib/semmle/python/dataflow/new/internal/TaintTrackingPrivate.qll

@@ -80,10 +80,8 @@ private module Cached {
     ) and
     model = ""
     or
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom
-          .(DataFlowPrivate::FlowSummaryNode)
-          .getSummaryNode(), nodeTo.(DataFlowPrivate::FlowSummaryNode).getSummaryNode(), false,
-      model)
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
+      nodeTo.(DataFlowPrivate::FlowSummaryNode).getSummaryNode(), false, model)
   }
 }
 

ruby/ql/lib/codeql/ruby/dataflow/internal/DataFlowPrivate.qll

@@ -198,8 +198,7 @@ module LocalFlow {
     FlowSummaryNode nodeFrom, FlowSummaryNode nodeTo, FlowSummaryImpl::Public::SummarizedCallable c,
     string model
   ) {
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.getSummaryNode(),
-      nodeTo.getSummaryNode(), true, model) and
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom, nodeTo.getSummaryNode(), true, model) and
     c = nodeFrom.getSummarizedCallable()
   }
 

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

@@ -18,6 +18,8 @@ module Input implements InputSig<Location, DataFlowImplSpecific::RubyDataFlow> {
 
   class SinkBase = Void;
 
+  class FlowSummaryCallBase = Void;
+
   predicate callableFromSource(SummarizedCallableBase c) { none() }
 
   ArgumentPosition callbackSelfParameterPosition() { result.isLambdaSelf() }
@@ -157,6 +159,10 @@ module Input implements InputSig<Location, DataFlowImplSpecific::RubyDataFlow> {
 private import Make<Location, DataFlowImplSpecific::RubyDataFlow, Input> as Impl
 
 private module StepsInput implements Impl::Private::StepsInputSig {
+  Impl::Private::SummaryNode getSummaryNode(Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   DataFlowCall getACall(Public::SummarizedCallable sc) {
     result.asCall().getAstNode() = sc.(LibraryCallable).getACall()
     or

ruby/ql/lib/codeql/ruby/dataflow/internal/TaintTrackingPrivate.qll

@@ -109,7 +109,7 @@ private module Cached {
     ) and
     model = ""
     or
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
       nodeTo.(FlowSummaryNode).getSummaryNode(), false, model)
     or
     any(FlowSteps::AdditionalTaintStep s).step(nodeFrom, nodeTo) and model = "AdditionalTaintStep"

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

@@ -180,7 +180,7 @@ Expr getPostUpdateReverseStep(Expr e, boolean preservesValue) {
 module LocalFlow {
   predicate flowSummaryLocalStep(Node nodeFrom, Node nodeTo, string model) {
     exists(FlowSummaryImpl::Public::SummarizedCallable c |
-      FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+      FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
         nodeTo.(FlowSummaryNode).getSummaryNode(), true, model) and
       c = nodeFrom.(FlowSummaryNode).getSummarizedCallable()
     )

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

@@ -11,6 +11,7 @@ private import codeql.rust.dataflow.FlowSummary
 private import codeql.rust.dataflow.Ssa
 private import codeql.rust.dataflow.internal.ModelsAsData
 private import Content
+private import Node
 
 predicate encodeContentTupleField(TupleFieldContent c, string arg) {
   exists(Addressable a, int pos, string prefix |
@@ -28,9 +29,12 @@ predicate encodeContentStructField(StructFieldContent c, string arg) {
 
 module Input implements InputSig<Location, RustDataFlow> {
   private import codeql.rust.frameworks.stdlib.Stdlib
+  private import codeql.util.Void
 
   class SummarizedCallableBase = Function;
 
+  class FlowSummaryCallBase = Void;
+
   predicate callableFromSource(SummarizedCallableBase c) { c.fromSource() }
 
   abstract private class SourceSinkBase extends AstNode {
@@ -144,6 +148,10 @@ module Input implements InputSig<Location, RustDataFlow> {
 private import Make<Location, RustDataFlow, Input> as Impl
 
 module StepsInput implements Impl::Private::StepsInputSig {
+  Impl::Private::SummaryNode getSummaryNode(RustDataFlow::Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   DataFlowCall getACall(Public::SummarizedCallable sc) { result.asCall().getStaticTarget() = sc }
 
   /** Gets the argument of `source` described by `sc`, if any. */

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

@@ -83,7 +83,7 @@ module RustTaintTrackingGen<DataFlowImpl::RustDataFlowInputSig I> implements
         pred.(Node::PostUpdateNode).getPreUpdateNode().asExpr(), _, succ, _)
     )
     or
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(pred.(Node::FlowSummaryNode).getSummaryNode(),
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(pred,
       succ.(Node::FlowSummaryNode).getSummaryNode(), false, model)
   }
 

shared/dataflow/codeql/dataflow/internal/FlowSummaryImpl.qll

@@ -54,6 +54,24 @@ signature module InputSig<LocationSig Location, DF::InputSig<Location> Lang> {
     none()
   }
 
+  /**
+   * A base class of calls that are candidates for flow summary modeling.
+   */
+  class FlowSummaryCallBase {
+    string toString();
+  }
+
+  /** Gets a call that targets summarized callable `sc`. */
+  default FlowSummaryCallBase getASourceCall(SummarizedCallableBase sc) { none() }
+
+  /** Gets the callable corresponding to summarized callable `c`. */
+  default Lang::DataFlowCallable getSummarizedCallableAsDataFlowCallable(SummarizedCallableBase c) {
+    none()
+  }
+
+  /** Gets the enclosing callable of `call`. */
+  default Lang::DataFlowCallable getSourceCallEnclosingCallable(FlowSummaryCallBase call) { none() }
+
   /** Gets the parameter position representing a callback itself, if any. */
   default Lang::ArgumentPosition callbackSelfParameterPosition() { none() }
 
@@ -74,6 +92,9 @@ signature module InputSig<LocationSig Location, DF::InputSig<Location> Lang> {
     result = getStandardReturnValueKind()
   }
 
+  /** Gets the parameter position corresponding to a flow-summary return kind `rk`, if any. */
+  default Lang::ParameterPosition getFlowSummaryParameterPosition(Lang::ReturnKind rk) { none() }
+
   /** Gets the textual representation of parameter position `pos` used in MaD. */
   string encodeParameterPosition(Lang::ParameterPosition pos);
 
@@ -660,6 +681,10 @@ module Make<
       s.length() = 1 and
       s.head() instanceof TArgumentSummaryComponent
       or
+      // ReturnValue.*
+      s.length() = 1 and
+      s.head() instanceof TReturnSummaryComponent
+      or
       // Argument[n].ReturnValue.*
       s.length() = 2 and
       s.head() instanceof TReturnSummaryComponent and
@@ -1137,6 +1162,13 @@ module Make<
       outputState(c, s) and s = SummaryComponentStack::argument(_)
     }
 
+    private predicate relevantFlowSummaryPosition(SummarizedCallable c, ReturnKind rk) {
+      exists(SummaryComponentStack input |
+        summary(c, input, _, _, _) and
+        input = TSingletonSummaryComponentStack(TReturnSummaryComponent(rk))
+      )
+    }
+
     pragma[nomagic]
     private predicate sourceOutputStateEntry(
       SourceElement source, SummaryComponentStack s, string kind, string model
@@ -1272,6 +1304,12 @@ module Make<
       TSummaryParameterNode(SummarizedCallable c, ParameterPosition pos) {
         summaryParameterNodeRange(c, pos)
       } or
+      TSummaryReturnArgumentNode(FlowSummaryCallBase call, ReturnKind rk) {
+        exists(SummarizedCallable sc |
+          call = getASourceCall(sc) and
+          relevantFlowSummaryPosition(sc, rk)
+        )
+      } or
       TSourceOutputNode(SourceElement source, SummaryNodeState state, string kind, string model) {
         state.isSourceOutputState(source, _, kind, model)
       } or
@@ -1321,6 +1359,40 @@ module Make<
       override SinkElement getSinkElement() { none() }
     }
 
+    private class SummaryReturnArgumentNode extends SummaryNode, TSummaryReturnArgumentNode {
+      private FlowSummaryCallBase call;
+      private ReturnKind rk;
+
+      SummaryReturnArgumentNode() { this = TSummaryReturnArgumentNode(call, rk) }
+
+      override string toString() { result = "[summary] value written to " + rk + " at " + call }
+
+      override SummarizedCallable getSummarizedCallable() { none() }
+
+      override SourceElement getSourceElement() { none() }
+
+      override SinkElement getSinkElement() { none() }
+    }
+
+    /**
+     * Gets the summary node that represents the argument node used to transfer
+     * flow into the caller when a value is written to the value returned by
+     * `call` with kind `rk`.
+     */
+    SummaryNode summaryArgumentNode(FlowSummaryCallBase call, ReturnKind rk) {
+      result = TSummaryReturnArgumentNode(call, rk)
+    }
+
+    /** Gets the enclosing callable for summary node `sn`. */
+    DataFlowCallable getEnclosingCallable(SummaryNode sn) {
+      result = getSummarizedCallableAsDataFlowCallable(sn.getSummarizedCallable())
+      or
+      exists(FlowSummaryCallBase call |
+        sn = TSummaryReturnArgumentNode(call, _) and
+        result = getSourceCallEnclosingCallable(call)
+      )
+    }
+
     class SourceOutputNode extends SummaryNode, TSourceOutputNode {
       private SourceElement source_;
       private SummaryNodeState state_;
@@ -1427,6 +1499,12 @@ module Make<
       SummarizedCallable c, SummaryNodeState state, ParameterPosition pos
     ) {
       state.isInputState(c, SummaryComponentStack::argument(pos))
+      or
+      exists(ReturnKind rk |
+        relevantFlowSummaryPosition(c, rk) and
+        state.isInputState(c, SummaryComponentStack::return(rk)) and
+        pos = getFlowSummaryParameterPosition(rk)
+      )
     }
 
     /**
@@ -1560,6 +1638,9 @@ module Make<
       )
     }
 
+    /** Holds if return kind `rk` is a relevant return kind for flow summary modeling. */
+    predicate relevantFlowSummaryPosition(ReturnKind rk) { relevantFlowSummaryPosition(_, rk) }
+
     /**
      * Holds if flow is allowed to pass from the parameter at position `pos` of `c`,
      * to a return node, and back out to the parameter.
@@ -1736,9 +1817,15 @@ module Make<
     }
 
     signature module StepsInputSig {
+      /** Gets the summary node represented by data-flow node `n`, if any. */
+      SummaryNode getSummaryNode(Node n);
+
       /** Gets a call that targets summarized callable `sc`. */
       DataFlowCall getACall(SummarizedCallable sc);
 
+      /** Gets the out node of kind `rk` for `call`, if any. */
+      default Node getSourceOutNode(FlowSummaryCallBase call, ReturnKind rk) { none() }
+
       /** Gets the enclosing callable of `source`. */
       DataFlowCallable getSourceNodeEnclosingCallable(SourceBase source);
 
@@ -1765,7 +1852,7 @@ module Make<
        * Holds if there is a local step from `pred` to `succ`, which is synthesized
        * from a flow summary.
        */
-      predicate summaryLocalStep(
+      private predicate summaryLocalStepImpl(
         SummaryNode pred, SummaryNode succ, boolean preservesValue, string model
       ) {
         exists(
@@ -1811,9 +1898,24 @@ module Make<
         )
       }
 
+      /** Holds if there is a local step between data-flow nodes synthesized from a flow summary. */
+      predicate summaryLocalStep(Node pred, SummaryNode succ, boolean preservesValue, string model) {
+        exists(SummaryNode predSummary |
+          predSummary = StepsInput::getSummaryNode(pred) and
+          summaryLocalStepImpl(predSummary, succ, preservesValue, model)
+        )
+        or
+        exists(FlowSummaryCallBase summaryCall, ReturnKind rk, SummarizedCallable sc |
+          pred = StepsInput::getSourceOutNode(summaryCall, rk) and
+          summaryCall = getASourceCall(sc) and
+          summary(sc, SummaryComponentStack::return(rk), _, preservesValue, model) and
+          succ = TSummaryReturnArgumentNode(summaryCall, rk)
+        )
+      }
+
       /** Holds if the value of `succ` is uniquely determined by the value of `pred`. */
       predicate summaryLocalMustFlowStep(SummaryNode pred, SummaryNode succ) {
-        pred = unique(SummaryNode n1 | summaryLocalStep(n1, succ, true, _))
+        pred = unique(SummaryNode n1 | summaryLocalStepImpl(n1, succ, true, _))
       }
 
       /**
@@ -1935,7 +2037,7 @@ module Make<
         or
         exists(SummaryNode mid, boolean clearsOrExpectsMid |
           paramReachesLocal(p, mid, clearsOrExpectsMid) and
-          summaryLocalStep(mid, n, true, _) and
+          summaryLocalStepImpl(mid, n, true, _) and
           if
             summaryClearsContent(n, _) or
             summaryExpectsContent(n, _)
@@ -1993,7 +2095,7 @@ module Make<
        */
       predicate summaryThroughStepValue(ArgNode arg, Node out, SummarizedCallable sc) {
         exists(SummaryNode ret |
-          summaryLocalStep(summaryArgParamRetOut(arg, ret, out, sc), ret, true, _)
+          summaryLocalStepImpl(summaryArgParamRetOut(arg, ret, out, sc), ret, true, _)
         )
       }
 
@@ -2006,7 +2108,7 @@ module Make<
        */
       predicate summaryThroughStepTaint(ArgNode arg, Node out, SummarizedCallable sc) {
         exists(SummaryNode ret |
-          summaryLocalStep(summaryArgParamRetOut(arg, ret, out, sc), ret, false, _)
+          summaryLocalStepImpl(summaryArgParamRetOut(arg, ret, out, sc), ret, false, _)
         )
       }
 
@@ -2020,7 +2122,7 @@ module Make<
       predicate summaryGetterStep(ArgNode arg, ContentSet c, Node out, SummarizedCallable sc) {
         exists(SummaryNode mid, SummaryNode ret |
           summaryReadStep(summaryArgParamRetOut(arg, ret, out, sc), c, mid) and
-          summaryLocalStep(mid, ret, _, _)
+          summaryLocalStepImpl(mid, ret, _, _)
         )
       }
 
@@ -2033,7 +2135,7 @@ module Make<
        */
       predicate summarySetterStep(ArgNode arg, ContentSet c, Node out, SummarizedCallable sc) {
         exists(SummaryNode mid, SummaryNode ret |
-          summaryLocalStep(summaryArgParamRetOut(arg, ret, out, sc), mid, _, _) and
+          summaryLocalStepImpl(summaryArgParamRetOut(arg, ret, out, sc), mid, _, _) and
           summaryStoreStep(mid, c, ret)
         )
       }
@@ -2749,9 +2851,11 @@ module Make<
         key = "semmle.label" and val = n.toString()
       }
 
+      private Node getNode(SummaryNode sn) { sn = StepsInput::getSummaryNode(result) }
+
       private predicate edgesComponent(NodeOrCall a, NodeOrCall b, string value) {
         exists(boolean preservesValue |
-          PrivateSteps::summaryLocalStep(a.asNode(), b.asNode(), preservesValue, _) and
+          PrivateSteps::summaryLocalStep(getNode(a.asNode()), b.asNode(), preservesValue, _) and
           if preservesValue = true then value = "value" else value = "taint"
         )
         or

swift/ql/lib/codeql/swift/dataflow/internal/DataFlowPrivate.qll

@@ -305,7 +305,7 @@ private module Cached {
     model = ""
     or
     // flow through a flow summary (extension of `SummaryModelCsv`)
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
       nodeTo.(FlowSummaryNode).getSummaryNode(), true, model)
   }
 

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

@@ -20,6 +20,8 @@ module Input implements InputSig<Location, DataFlowImplSpecific::SwiftDataFlow>
 
   class SinkBase = Void;
 
+  class FlowSummaryCallBase = Void;
+
   predicate callableFromSource(SummarizedCallableBase c) { c.hasBody() }
 
   ArgumentPosition callbackSelfParameterPosition() { result instanceof ThisArgumentPosition }
@@ -113,6 +115,10 @@ module Input implements InputSig<Location, DataFlowImplSpecific::SwiftDataFlow>
 private import Make<Location, DataFlowImplSpecific::SwiftDataFlow, Input> as Impl
 
 private module StepsInput implements Impl::Private::StepsInputSig {
+  Impl::Private::SummaryNode getSummaryNode(Node n) {
+    result = n.(FlowSummaryNode).getSummaryNode()
+  }
+
   DataFlowCall getACall(Public::SummarizedCallable sc) { result.asCall().getStaticTarget() = sc }
 
   DataFlowCallable getSourceNodeEnclosingCallable(Input::SourceBase source) { none() }

swift/ql/lib/codeql/swift/dataflow/internal/TaintTrackingPrivate.qll

@@ -76,7 +76,7 @@ private module Cached {
     model = ""
     or
     // flow through a flow summary (extension of `SummaryModelCsv`)
-    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom.(FlowSummaryNode).getSummaryNode(),
+    FlowSummaryImpl::Private::Steps::summaryLocalStep(nodeFrom,
       nodeTo.(FlowSummaryNode).getSummaryNode(), false, model)
     or
     any(AdditionalTaintStep a).step(nodeFrom, nodeTo) and model = "AdditionalTaintStep"