Merge branch 'main' into pythonXpath

python/.vscode/ql.code-snippets

@@ -180,8 +180,6 @@
             "",
             "  /** A direct instantiation of `${TM_SELECTED_TEXT}`. */",
             "  private class ClassInstantiation extends InstanceSource, DataFlow::CallCfgNode {",
-            "      override CallNode node;",
-            "",
             "      ClassInstantiation() { this = classRef().getACall() }",
             "  }",
             "",
@@ -195,11 +193,55 @@
             "",
             "  /** Gets a reference to an instance of `${TM_SELECTED_TEXT}`. */",
             "  DataFlow::Node instance() { instance(DataFlow::TypeTracker::end()).flowsTo(result) }",
+            "",
+            "  /**",
+            "   * Taint propagation for `${TM_SELECTED_TEXT}`.",
+            "   */",
+            "  private class InstanceTaintSteps extends InstanceTaintStepsHelper {",
+            "    InstanceTaintSteps() { this = \"${TM_SELECTED_TEXT}\" }",
+            "    ",
+            "    override DataFlow::Node getInstance() { result = instance() }",
+            "    ",
+            "    override string getAttributeName() { none() }",
+            "    ",
+            "    override string getMethodName() { none() }",
+            "    ",
+            "    override string getAsyncMethodName() { none() }",
+            "  }",
+            "",
+            "  /**",
+            "   * Extra taint propagation for `${TM_SELECTED_TEXT}`, not covered by `InstanceTaintSteps`.",
+            "   */",
+            "  private class AdditionalTaintStep extends TaintTracking::AdditionalTaintStep {",
+            "    override predicate step(DataFlow::Node nodeFrom, DataFlow::Node nodeTo) {",
+            "      // TODO",
+            "      none()",
+            "    }",
+            "  }",
             "}",
         ],
         "description": "Type tracking class (select full class path before inserting)",
     },
-
+    "foo": {
+        "scope": "ql",
+        "prefix": "foo",
+        "body": [
+            "    /**",
+            "     * Taint propagation for `$1`.",
+            "     */",
+            "     private class InstanceTaintSteps extends InstanceTaintStepsHelper {",
+            "        InstanceTaintSteps() { this = \"$1\" }",
+            "",
+            "        override DataFlow::Node getInstance() { result = instance() }",
+            "",
+            "        override string getAttributeName() { none() }",
+            "",
+            "        override string getMethodName() { none() }",
+            "",
+            "        override string getAsyncMethodName() { none() }",
+            "      }",
+        ],
+    },
     "API graph .getMember chain": {
         "scope": "ql",
         "prefix": "api graph .getMember chain",

python/change-notes/2021-06-25-add-peewee-modeling.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Added modeling of raw SQL execution from the PyPI package `peewee`.

python/change-notes/2021-07-12-add-typetrackingnode.md

@@ -1,3 +1,2 @@
 lgtm,codescanning
-* The `track` and `backtrack` methods on `LocalSourceNode` have been deprecated. When writing
-  type trackers, the corresponding methods on `TypeTrackingNode` should be used instead.
+* The `track` and `backtrack` methods on `LocalSourceNode` are in the process of being deprecated. When using type trackers, the corresponding methods on `TypeTrackingNode` should be used instead.

python/change-notes/2021-07-16-deprecate-importnode.md

@@ -0,0 +1,4 @@
+lgtm,codescanning
+* The `importNode` predicate from the data-flow library has been deprecated. In its place, we
+  recommend using the API graphs library, accessible via `import semmle.python.ApiGraphs`.
+  

python/change-notes/2021-07-28-port-RoDoS-queries.md

@@ -1,3 +1,3 @@
 lgtm,codescanning
-* Added _Inefficient regular expression_ (`py/redos`) query, which is already available in JavaScript.
-* Added _Polynomial regular expression used on uncontrolled data_ (`py/polynomial-redos`), which is already available in JavaScript.
+* Added an experimental _Inefficient regular expression_ (`py/redos`) query, which is already available in JavaScript.
+* Added an experimental _Polynomial regular expression used on uncontrolled data_ (`py/polynomial-redos`), which is already available in JavaScript.

python/change-notes/2021-08-30-port-modifying-default-query.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Updated _Modification of parameter with default_ (`py/modification-of-default-value`) query to use the new data flow library instead of the old taint tracking library and to remove the use of points-to analysis. You may see differences in the results found by the query, but overall this change should result in a more robust and accurate analysis.

python/change-notes/2021-09-02-add-Flask-SQLAlchemy-modeling.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Added modeling of SQL execution in the `Flask-SQLAlchemy` PyPI package, resulting in additional sinks for the SQL Injection query (`py/sql-injection`).

python/change-notes/2021-09-02-add-SQLAlchemy-modeling.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Added modeling of SQL execution in the `SQLAlchemy` PyPI package, resulting in additional sinks for the SQL Injection query (`py/sql-injection`). This modeling was originally [submitted as a contribution by @mrthankyou](https://github.com/github/codeql/pull/5680).

python/change-notes/2021-09-02-add-SQLAlchemyTextClauseInjection.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Expanded the query _SQL query built from user-controlled sources_ (`py/sql-injection`) to alert if user-input is added to a TextClause from SQLAlchemy, since that can lead to SQL injection.

python/change-notes/2021-09-08-add-flow-from-default-values.md

@@ -0,0 +1,2 @@
+lgtm,codescanning
+* Function parameters with default values will now see flow from those values.

python/ql/examples/qlpack.lock.yml

@@ -0,0 +1,4 @@
+---
+dependencies: {}
+compiled: false
+lockVersion: 1.0.0

python/ql/examples/qlpack.yml

@@ -1,3 +1,4 @@
-name: codeql-python-examples
-version: 0.0.0
-libraryPathDependencies: codeql-python
+name: codeql/python-examples
+version: 0.0.2
+dependencies:
+    codeql/python-all: "*"

python/ql/lib/qlpack.lock.yml

@@ -0,0 +1,4 @@
+---
+dependencies: {}
+compiled: false
+lockVersion: 1.0.0

python/ql/lib/qlpack.yml

@@ -0,0 +1,7 @@
+name: codeql/python-all
+version: 0.0.2
+dbscheme: semmlecode.python.dbscheme
+extractor: python
+library: true
+dependencies:
+    codeql/python-upgrades: 0.0.2

python/ql/lib/semmle/python/ApiGraphs.qll

@@ -424,13 +424,8 @@ module API {
      * a value in the module `m`.
      */
     private predicate possible_builtin_defined_in_module(string name, Module m) {
-      exists(NameNode n |
-        not exists(LocalVariable v | n.defines(v)) and
-        n.isStore() and
-        name = n.getId() and
-        name = getBuiltInName() and
-        m = n.getEnclosingModule()
-      )
+      global_name_defined_in_module(name, m) and
+      name = getBuiltInName()
     }
 
     /**
@@ -445,6 +440,51 @@ module API {
       m = n.getEnclosingModule()
     }
 
+    /**
+     * Holds if `n` is an access of a variable called `name` (which is _not_ the name of a
+     * built-in, and which is _not_ a global defined in the enclosing module) inside the scope `s`.
+     */
+    private predicate name_possibly_defined_in_import_star(NameNode n, string name, Scope s) {
+      n.isLoad() and
+      name = n.getId() and
+      // Not already defined in an enclosing scope.
+      not exists(LocalVariable v |
+        v.getId() = name and v.getScope() = n.getScope().getEnclosingScope*()
+      ) and
+      not name = getBuiltInName() and
+      s = n.getScope().getEnclosingScope*() and
+      exists(potential_import_star_base(s)) and
+      not global_name_defined_in_module(name, n.getEnclosingModule())
+    }
+
+    /** Holds if a global variable called `name` is assigned a value in the module `m`. */
+    private predicate global_name_defined_in_module(string name, Module m) {
+      exists(NameNode n |
+        not exists(LocalVariable v | n.defines(v)) and
+        n.isStore() and
+        name = n.getId() and
+        m = n.getEnclosingModule()
+      )
+    }
+
+    /**
+     * Gets the API graph node for all modules imported with `from ... import *` inside the scope `s`.
+     *
+     * For example, given
+     *
+     * `from foo.bar import *`
+     *
+     * this would be the API graph node with the path
+     *
+     * `moduleImport("foo").getMember("bar")`
+     */
+    private TApiNode potential_import_star_base(Scope s) {
+      exists(DataFlow::Node ref |
+        ref.asCfgNode() = any(ImportStarNode n | n.getScope() = s).getModule() and
+        use(result, ref)
+      )
+    }
+
     /**
      * Holds if `ref` is a use of a node that should have an incoming edge from `base` labeled
      * `lbl` in the API graph.
@@ -487,6 +527,15 @@ module API {
       // Built-ins, treated as members of the module `builtins`
       base = MkModuleImport("builtins") and
       lbl = Label::member(any(string name | ref = likely_builtin(name)))
+      or
+      // Unknown variables that may belong to a module imported with `import *`
+      exists(Scope s |
+        base = potential_import_star_base(s) and
+        lbl =
+          Label::member(any(string name |
+              name_possibly_defined_in_import_star(ref.asCfgNode(), name, s)
+            ))
+      )
     }
 
     /**

python/ql/lib/semmle/python/AstExtended.qll

@@ -49,12 +49,15 @@ abstract class AstNode extends AstNode_ {
   /** Whether this contains `inner` syntactically */
   predicate contains(AstNode inner) { this.getAChildNode+() = inner }
 
-  /** Whether this contains `inner` syntactically and `inner` has the same scope as `this` */
-  predicate containsInScope(AstNode inner) {
+  pragma[noinline]
+  private predicate containsInScope(AstNode inner, Scope scope) {
     this.contains(inner) and
-    this.getScope() = inner.getScope() and
-    not inner instanceof Scope
+    not inner instanceof Scope and
+    scope = this.getScope()
   }
+
+  /** Whether this contains `inner` syntactically and `inner` has the same scope as `this` */
+  predicate containsInScope(AstNode inner) { this.containsInScope(inner, inner.getScope()) }
 }
 
 /* Parents */

python/ql/lib/semmle/python/Files.qll

@@ -1,9 +1,7 @@
 import python
 
 /** A file */
-class File extends Container {
-  File() { files(this, _, _, _, _) }
-
+class File extends Container, @file {
   /** DEPRECATED: Use `getAbsolutePath` instead. */
   deprecated override string getName() { result = this.getAbsolutePath() }
 
@@ -34,9 +32,7 @@ class File extends Container {
   }
 
   /** Gets a short name for this file (just the file name) */
-  string getShortName() {
-    exists(string simple, string ext | files(this, _, simple, ext, _) | result = simple + ext)
-  }
+  string getShortName() { result = this.getBaseName() }
 
   private int lastLine() {
     result = max(int i | exists(Location l | l.getFile() = this and l.getEndLine() = i))
@@ -55,7 +51,7 @@ class File extends Container {
     )
   }
 
-  override string getAbsolutePath() { files(this, result, _, _, _) }
+  override string getAbsolutePath() { files(this, result) }
 
   /** Gets the URL of this file. */
   override string getURL() { result = "file://" + this.getAbsolutePath() + ":0:0:0:0" }
@@ -118,15 +114,10 @@ private predicate occupied_line(File f, int n) {
 }
 
 /** A folder (directory) */
-class Folder extends Container {
-  Folder() { folders(this, _, _) }
-
+class Folder extends Container, @folder {
   /** DEPRECATED: Use `getAbsolutePath` instead. */
   deprecated override string getName() { result = this.getAbsolutePath() }
 
-  /** DEPRECATED: Use `getBaseName` instead. */
-  deprecated string getSimple() { folders(this, _, result) }
-
   /**
    * Holds if this element is at the specified location.
    * The location spans column `startcolumn` of line `startline` to
@@ -144,7 +135,7 @@ class Folder extends Container {
     endcolumn = 0
   }
 
-  override string getAbsolutePath() { folders(this, result, _) }
+  override string getAbsolutePath() { folders(this, result) }
 
   /** Gets the URL of this folder. */
   override string getURL() { result = "folder://" + this.getAbsolutePath() }

python/ql/lib/semmle/python/Flow.qll

@@ -653,6 +653,8 @@ class DefinitionNode extends ControlFlowNode {
   DefinitionNode() {
     exists(Assign a | a.getATarget().getAFlowNode() = this)
     or
+    exists(AnnAssign a | a.getTarget().getAFlowNode() = this and exists(a.getValue()))
+    or
     exists(Alias a | a.getAsname().getAFlowNode() = this)
     or
     augstore(_, this)
@@ -795,6 +797,9 @@ private AstNode assigned_value(Expr lhs) {
   /* lhs = result */
   exists(Assign a | a.getATarget() = lhs and result = a.getValue())
   or
+  /* lhs : annotation = result */
+  exists(AnnAssign a | a.getTarget() = lhs and result = a.getValue())
+  or
   /* import result as lhs */
   exists(Alias a | a.getAsname() = lhs and result = a.getValue())
   or

python/ql/lib/semmle/python/Frameworks.qll

@@ -13,6 +13,7 @@ private import semmle.python.frameworks.Dill
 private import semmle.python.frameworks.Django
 private import semmle.python.frameworks.Fabric
 private import semmle.python.frameworks.Flask
+private import semmle.python.frameworks.FlaskSqlAlchemy
 private import semmle.python.frameworks.Idna
 private import semmle.python.frameworks.Invoke
 private import semmle.python.frameworks.Jmespath
@@ -20,10 +21,12 @@ private import semmle.python.frameworks.MarkupSafe
 private import semmle.python.frameworks.Multidict
 private import semmle.python.frameworks.Mysql
 private import semmle.python.frameworks.MySQLdb
+private import semmle.python.frameworks.Peewee
 private import semmle.python.frameworks.Psycopg2
 private import semmle.python.frameworks.PyMySQL
 private import semmle.python.frameworks.Rsa
 private import semmle.python.frameworks.Simplejson
+private import semmle.python.frameworks.SqlAlchemy
 private import semmle.python.frameworks.Stdlib
 private import semmle.python.frameworks.Tornado
 private import semmle.python.frameworks.Twisted

python/ql/lib/semmle/python/RegexTreeView.qll

@@ -7,6 +7,10 @@ private import semmle.python.regex
  * An element containing a regular expression term, that is, either
  * a string literal (parsed as a regular expression)
  * or another regular expression term.
+ *
+ * For sequences and alternations, we require at least one child.
+ * Otherwise, we wish to represent the term differently.
+ * This avoids multiple representations of the same term.
  */
 newtype TRegExpParent =
   /** A string literal used as a regular expression */
@@ -14,9 +18,18 @@ newtype TRegExpParent =
   /** A quantified term */
   TRegExpQuantifier(Regex re, int start, int end) { re.qualifiedItem(start, end, _, _) } or
   /** A sequence term */
-  TRegExpSequence(Regex re, int start, int end) { re.sequence(start, end) } or
-  /** An alternatio term */
-  TRegExpAlt(Regex re, int start, int end) { re.alternation(start, end) } or
+  TRegExpSequence(Regex re, int start, int end) {
+    re.sequence(start, end) and
+    exists(seqChild(re, start, end, 1)) // if a sequence does not have more than one element, it should be treated as that element instead.
+  } or
+  /** An alternation term */
+  TRegExpAlt(Regex re, int start, int end) {
+    re.alternation(start, end) and
+    exists(int part_end |
+      re.alternationOption(start, end, start, part_end) and
+      part_end < end
+    ) // if an alternation does not have more than one element, it should be treated as that element instead.
+  } or
   /** A character class term */
   TRegExpCharacterClass(Regex re, int start, int end) { re.charSet(start, end) } or
   /** A character range term */
@@ -61,6 +74,10 @@ class RegExpLiteral extends TRegExpLiteral, RegExpParent {
 
   predicate isDotAll() { re.getAMode() = "DOTALL" }
 
+  predicate isIgnoreCase() { re.getAMode() = "IGNORECASE" }
+
+  string getFlags() { result = concat(string mode | mode = re.getAMode() | mode, " | ") }
+
   override Regex getRegex() { result = re }
 
   string getPrimaryQLClass() { result = "RegExpLiteral" }
@@ -89,8 +106,7 @@ class RegExpTerm extends RegExpParent {
     or
     this = TRegExpQuantifier(re, start, end)
     or
-    this = TRegExpSequence(re, start, end) and
-    exists(seqChild(re, start, end, 1)) // if a sequence does not have more than one element, it should be treated as that element instead.
+    this = TRegExpSequence(re, start, end)
     or
     this = TRegExpSpecialChar(re, start, end)
   }
@@ -337,10 +353,7 @@ class RegExpRange extends RegExpQuantifier {
  * This is a sequence with the elements `(ECMA|Java)` and `Script`.
  */
 class RegExpSequence extends RegExpTerm, TRegExpSequence {
-  RegExpSequence() {
-    this = TRegExpSequence(re, start, end) and
-    exists(seqChild(re, start, end, 1)) // if a sequence does not have more than one element, it should be treated as that element instead.
-  }
+  RegExpSequence() { this = TRegExpSequence(re, start, end) }
 
   override RegExpTerm getChild(int i) { result = seqChild(re, start, end, i) }
 
@@ -836,6 +849,15 @@ class RegExpZeroWidthMatch extends RegExpGroup {
  */
 class RegExpSubPattern extends RegExpZeroWidthMatch {
   RegExpSubPattern() { not re.emptyGroup(start, end) }
+
+  /** Gets the lookahead term. */
+  RegExpTerm getOperand() {
+    exists(int in_start, int in_end | re.groupContents(start, end, in_start, in_end) |
+      result.getRegex() = re and
+      result.getStart() = in_start and
+      result.getEnd() = in_end
+    )
+  }
 }
 
 /**

python/ql/lib/semmle/python/Stmts.qll

@@ -153,6 +153,12 @@ class ExceptStmt extends ExceptStmt_ {
   override Stmt getASubStatement() { result = this.getAStmt() }
 
   override Stmt getLastStatement() { result = this.getBody().getLastItem().getLastStatement() }
+
+  override Expr getType() {
+    result = super.getType() and not result instanceof Tuple
+    or
+    result = super.getType().(Tuple).getAnElt()
+  }
 }
 
 /** An assert statement, such as `assert a == b, "A is not equal to b"` */

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

@@ -923,28 +923,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1173,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1860,7 +1862,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2117,7 +2120,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2618,7 +2621,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -3258,24 +3262,16 @@ class PathNode extends TPathNode {
   /** Gets the associated configuration. */
   Configuration getConfiguration() { none() }
 
-  private predicate isHidden() {
-    hiddenNode(this.(PathNodeImpl).getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.(PathNodeImpl).getNodeEx() instanceof TNodeImplicitRead
-  }
-
   private PathNode getASuccessorIfHidden() {
-    this.isHidden() and
+    this.(PathNodeImpl).isHidden() and
     result = this.(PathNodeImpl).getASuccessorImpl()
   }
 
   /** Gets a successor of this node, if any. */
   final PathNode getASuccessor() {
     result = this.(PathNodeImpl).getASuccessorImpl().getASuccessorIfHidden*() and
-    not this.isHidden() and
-    not result.isHidden()
+    not this.(PathNodeImpl).isHidden() and
+    not result.(PathNodeImpl).isHidden()
   }
 
   /** Holds if this node is a source. */
@@ -3287,6 +3283,14 @@ abstract private class PathNodeImpl extends PathNode {
 
   abstract NodeEx getNodeEx();
 
+  predicate isHidden() {
+    hiddenNode(this.getNodeEx().asNode()) and
+    not this.isSource() and
+    not this instanceof PathNodeSink
+    or
+    this.getNodeEx() instanceof TNodeImplicitRead
+  }
+
   private string ppAp() {
     this instanceof PathNodeSink and result = ""
     or
@@ -3313,10 +3317,15 @@ abstract private class PathNodeImpl extends PathNode {
 }
 
 /** Holds if `n` can reach a sink. */
-private predicate reach(PathNode n) { n instanceof PathNodeSink or reach(n.getASuccessor()) }
+private predicate directReach(PathNode n) {
+  n instanceof PathNodeSink or directReach(n.getASuccessor())
+}
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n` can reach a sink or is used in a subpath. */
+private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
+
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3325,12 +3334,14 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
     reach(n) and key = "semmle.label" and val = n.toString()
   }
+
+  query predicate subpaths = Subpaths::subpaths/4;
 }
 
 /**
@@ -3622,6 +3633,87 @@ private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext c
   )
 }
 
+private module Subpaths {
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple and `ret` is determined by
+   * `kind`, `sc`, `apout`, and `innercc`.
+   */
+  pragma[nomagic]
+  private predicate subpaths01(
+    PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
+    NodeEx out, AccessPath apout
+  ) {
+    pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+    pathIntoCallable(arg, par, _, innercc, sc, _) and
+    paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _,
+      unbindConf(arg.getConfiguration()))
+  }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple and `ret` is determined by
+   * `kind`, `sc`, `apout`, and `innercc`.
+   */
+  pragma[nomagic]
+  private predicate subpaths02(
+    PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
+    NodeEx out, AccessPath apout
+  ) {
+    subpaths01(arg, par, sc, innercc, kind, out, apout) and
+    out.asNode() = kind.getAnOutNode(_)
+  }
+
+  pragma[nomagic]
+  private Configuration getPathNodeConf(PathNode n) { result = n.getConfiguration() }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple.
+   */
+  pragma[nomagic]
+  private predicate subpaths03(
+    PathNode arg, ParamNodeEx par, PathNodeMid ret, NodeEx out, AccessPath apout
+  ) {
+    exists(SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind, RetNodeEx retnode |
+      subpaths02(arg, par, sc, innercc, kind, out, apout) and
+      ret.getNodeEx() = retnode and
+      kind = retnode.getKind() and
+      innercc = ret.getCallContext() and
+      sc = ret.getSummaryCtx() and
+      ret.getConfiguration() = unbindConf(getPathNodeConf(arg)) and
+      apout = ret.getAp() and
+      not ret.isHidden()
+    )
+  }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
+   * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
+   * `ret -> out` is summarized as the edge `arg -> out`.
+   */
+  predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
+    exists(ParamNodeEx p, NodeEx o, AccessPath apout |
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
+      subpaths03(arg, p, ret, o, apout) and
+      par.getNodeEx() = p and
+      out.getNodeEx() = o and
+      out.getAp() = apout
+    )
+  }
+
+  /**
+   * Holds if `n` can reach a return node in a summarized subpath.
+   */
+  predicate retReach(PathNode n) {
+    subpaths(_, _, n, _)
+    or
+    exists(PathNode mid |
+      retReach(mid) and
+      n.getASuccessor() = mid and
+      not subpaths(_, mid, _, _)
+    )
+  }
+}
+
 /**
  * Holds if data can flow (inter-procedurally) from `source` to `sink`.
  *

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowImpl2.qll

@@ -923,28 +923,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1173,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1860,7 +1862,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2117,7 +2120,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2618,7 +2621,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -3258,24 +3262,16 @@ class PathNode extends TPathNode {
   /** Gets the associated configuration. */
   Configuration getConfiguration() { none() }
 
-  private predicate isHidden() {
-    hiddenNode(this.(PathNodeImpl).getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.(PathNodeImpl).getNodeEx() instanceof TNodeImplicitRead
-  }
-
   private PathNode getASuccessorIfHidden() {
-    this.isHidden() and
+    this.(PathNodeImpl).isHidden() and
     result = this.(PathNodeImpl).getASuccessorImpl()
   }
 
   /** Gets a successor of this node, if any. */
   final PathNode getASuccessor() {
     result = this.(PathNodeImpl).getASuccessorImpl().getASuccessorIfHidden*() and
-    not this.isHidden() and
-    not result.isHidden()
+    not this.(PathNodeImpl).isHidden() and
+    not result.(PathNodeImpl).isHidden()
   }
 
   /** Holds if this node is a source. */
@@ -3287,6 +3283,14 @@ abstract private class PathNodeImpl extends PathNode {
 
   abstract NodeEx getNodeEx();
 
+  predicate isHidden() {
+    hiddenNode(this.getNodeEx().asNode()) and
+    not this.isSource() and
+    not this instanceof PathNodeSink
+    or
+    this.getNodeEx() instanceof TNodeImplicitRead
+  }
+
   private string ppAp() {
     this instanceof PathNodeSink and result = ""
     or
@@ -3313,10 +3317,15 @@ abstract private class PathNodeImpl extends PathNode {
 }
 
 /** Holds if `n` can reach a sink. */
-private predicate reach(PathNode n) { n instanceof PathNodeSink or reach(n.getASuccessor()) }
+private predicate directReach(PathNode n) {
+  n instanceof PathNodeSink or directReach(n.getASuccessor())
+}
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n` can reach a sink or is used in a subpath. */
+private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
+
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3325,12 +3334,14 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
     reach(n) and key = "semmle.label" and val = n.toString()
   }
+
+  query predicate subpaths = Subpaths::subpaths/4;
 }
 
 /**
@@ -3622,6 +3633,87 @@ private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext c
   )
 }
 
+private module Subpaths {
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple and `ret` is determined by
+   * `kind`, `sc`, `apout`, and `innercc`.
+   */
+  pragma[nomagic]
+  private predicate subpaths01(
+    PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
+    NodeEx out, AccessPath apout
+  ) {
+    pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+    pathIntoCallable(arg, par, _, innercc, sc, _) and
+    paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _,
+      unbindConf(arg.getConfiguration()))
+  }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple and `ret` is determined by
+   * `kind`, `sc`, `apout`, and `innercc`.
+   */
+  pragma[nomagic]
+  private predicate subpaths02(
+    PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
+    NodeEx out, AccessPath apout
+  ) {
+    subpaths01(arg, par, sc, innercc, kind, out, apout) and
+    out.asNode() = kind.getAnOutNode(_)
+  }
+
+  pragma[nomagic]
+  private Configuration getPathNodeConf(PathNode n) { result = n.getConfiguration() }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple.
+   */
+  pragma[nomagic]
+  private predicate subpaths03(
+    PathNode arg, ParamNodeEx par, PathNodeMid ret, NodeEx out, AccessPath apout
+  ) {
+    exists(SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind, RetNodeEx retnode |
+      subpaths02(arg, par, sc, innercc, kind, out, apout) and
+      ret.getNodeEx() = retnode and
+      kind = retnode.getKind() and
+      innercc = ret.getCallContext() and
+      sc = ret.getSummaryCtx() and
+      ret.getConfiguration() = unbindConf(getPathNodeConf(arg)) and
+      apout = ret.getAp() and
+      not ret.isHidden()
+    )
+  }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
+   * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
+   * `ret -> out` is summarized as the edge `arg -> out`.
+   */
+  predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
+    exists(ParamNodeEx p, NodeEx o, AccessPath apout |
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
+      subpaths03(arg, p, ret, o, apout) and
+      par.getNodeEx() = p and
+      out.getNodeEx() = o and
+      out.getAp() = apout
+    )
+  }
+
+  /**
+   * Holds if `n` can reach a return node in a summarized subpath.
+   */
+  predicate retReach(PathNode n) {
+    subpaths(_, _, n, _)
+    or
+    exists(PathNode mid |
+      retReach(mid) and
+      n.getASuccessor() = mid and
+      not subpaths(_, mid, _, _)
+    )
+  }
+}
+
 /**
  * Holds if data can flow (inter-procedurally) from `source` to `sink`.
  *

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowImpl3.qll

@@ -923,28 +923,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1173,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1860,7 +1862,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2117,7 +2120,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2618,7 +2621,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -3258,24 +3262,16 @@ class PathNode extends TPathNode {
   /** Gets the associated configuration. */
   Configuration getConfiguration() { none() }
 
-  private predicate isHidden() {
-    hiddenNode(this.(PathNodeImpl).getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.(PathNodeImpl).getNodeEx() instanceof TNodeImplicitRead
-  }
-
   private PathNode getASuccessorIfHidden() {
-    this.isHidden() and
+    this.(PathNodeImpl).isHidden() and
     result = this.(PathNodeImpl).getASuccessorImpl()
   }
 
   /** Gets a successor of this node, if any. */
   final PathNode getASuccessor() {
     result = this.(PathNodeImpl).getASuccessorImpl().getASuccessorIfHidden*() and
-    not this.isHidden() and
-    not result.isHidden()
+    not this.(PathNodeImpl).isHidden() and
+    not result.(PathNodeImpl).isHidden()
   }
 
   /** Holds if this node is a source. */
@@ -3287,6 +3283,14 @@ abstract private class PathNodeImpl extends PathNode {
 
   abstract NodeEx getNodeEx();
 
+  predicate isHidden() {
+    hiddenNode(this.getNodeEx().asNode()) and
+    not this.isSource() and
+    not this instanceof PathNodeSink
+    or
+    this.getNodeEx() instanceof TNodeImplicitRead
+  }
+
   private string ppAp() {
     this instanceof PathNodeSink and result = ""
     or
@@ -3313,10 +3317,15 @@ abstract private class PathNodeImpl extends PathNode {
 }
 
 /** Holds if `n` can reach a sink. */
-private predicate reach(PathNode n) { n instanceof PathNodeSink or reach(n.getASuccessor()) }
+private predicate directReach(PathNode n) {
+  n instanceof PathNodeSink or directReach(n.getASuccessor())
+}
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n` can reach a sink or is used in a subpath. */
+private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
+
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3325,12 +3334,14 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
     reach(n) and key = "semmle.label" and val = n.toString()
   }
+
+  query predicate subpaths = Subpaths::subpaths/4;
 }
 
 /**
@@ -3622,6 +3633,87 @@ private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext c
   )
 }
 
+private module Subpaths {
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple and `ret` is determined by
+   * `kind`, `sc`, `apout`, and `innercc`.
+   */
+  pragma[nomagic]
+  private predicate subpaths01(
+    PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
+    NodeEx out, AccessPath apout
+  ) {
+    pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+    pathIntoCallable(arg, par, _, innercc, sc, _) and
+    paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _,
+      unbindConf(arg.getConfiguration()))
+  }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple and `ret` is determined by
+   * `kind`, `sc`, `apout`, and `innercc`.
+   */
+  pragma[nomagic]
+  private predicate subpaths02(
+    PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
+    NodeEx out, AccessPath apout
+  ) {
+    subpaths01(arg, par, sc, innercc, kind, out, apout) and
+    out.asNode() = kind.getAnOutNode(_)
+  }
+
+  pragma[nomagic]
+  private Configuration getPathNodeConf(PathNode n) { result = n.getConfiguration() }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple.
+   */
+  pragma[nomagic]
+  private predicate subpaths03(
+    PathNode arg, ParamNodeEx par, PathNodeMid ret, NodeEx out, AccessPath apout
+  ) {
+    exists(SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind, RetNodeEx retnode |
+      subpaths02(arg, par, sc, innercc, kind, out, apout) and
+      ret.getNodeEx() = retnode and
+      kind = retnode.getKind() and
+      innercc = ret.getCallContext() and
+      sc = ret.getSummaryCtx() and
+      ret.getConfiguration() = unbindConf(getPathNodeConf(arg)) and
+      apout = ret.getAp() and
+      not ret.isHidden()
+    )
+  }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
+   * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
+   * `ret -> out` is summarized as the edge `arg -> out`.
+   */
+  predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
+    exists(ParamNodeEx p, NodeEx o, AccessPath apout |
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
+      subpaths03(arg, p, ret, o, apout) and
+      par.getNodeEx() = p and
+      out.getNodeEx() = o and
+      out.getAp() = apout
+    )
+  }
+
+  /**
+   * Holds if `n` can reach a return node in a summarized subpath.
+   */
+  predicate retReach(PathNode n) {
+    subpaths(_, _, n, _)
+    or
+    exists(PathNode mid |
+      retReach(mid) and
+      n.getASuccessor() = mid and
+      not subpaths(_, mid, _, _)
+    )
+  }
+}
+
 /**
  * Holds if data can flow (inter-procedurally) from `source` to `sink`.
  *

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowImpl4.qll

@@ -923,28 +923,29 @@ private module Stage2 {
 
   ApOption apSome(Ap ap) { result = TBooleanSome(ap) }
 
-  class Cc = boolean;
+  class Cc = CallContext;
 
-  class CcCall extends Cc {
-    CcCall() { this = true }
+  class CcCall = CallContextCall;
 
-    /** Holds if this call context may be `call`. */
-    predicate matchesCall(DataFlowCall call) { any() }
-  }
+  class CcNoCall = CallContextNoCall;
 
-  class CcNoCall extends Cc {
-    CcNoCall() { this = false }
-  }
-
-  Cc ccNone() { result = false }
+  Cc ccNone() { result instanceof CallContextAny }
 
   private class LocalCc = Unit;
 
   bindingset[call, c, outercc]
-  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) { any() }
+  private CcCall getCallContextCall(DataFlowCall call, DataFlowCallable c, Cc outercc) {
+    checkCallContextCall(outercc, call, c) and
+    if recordDataFlowCallSiteDispatch(call, c)
+    then result = TSpecificCall(call)
+    else result = TSomeCall()
+  }
 
   bindingset[call, c, innercc]
-  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) { any() }
+  private CcNoCall getCallContextReturn(DataFlowCallable c, DataFlowCall call, Cc innercc) {
+    checkCallContextReturn(innercc, c, call) and
+    if reducedViableImplInReturn(c, call) then result = TReturn(c, call) else result = ccNone()
+  }
 
   bindingset[node, cc, config]
   private LocalCc getLocalCc(NodeEx node, Cc cc, Configuration config) { any() }
@@ -1172,7 +1173,8 @@ private module Stage2 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -1860,7 +1862,8 @@ private module Stage3 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -2117,7 +2120,7 @@ private module Stage3 {
 private predicate flowCandSummaryCtx(NodeEx node, AccessPathFront argApf, Configuration config) {
   exists(AccessPathFront apf |
     Stage3::revFlow(node, true, _, apf, config) and
-    Stage3::fwdFlow(node, true, TAccessPathFrontSome(argApf), apf, config)
+    Stage3::fwdFlow(node, any(Stage3::CcCall ccc), TAccessPathFrontSome(argApf), apf, config)
   )
 }
 
@@ -2618,7 +2621,8 @@ private module Stage4 {
       fwdFlow(out, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), ap,
         pragma[only_bind_into](config)) and
       fwdFlowOutFromArg(call, out, argAp0, ap, config) and
-      fwdFlowIsEntered(call, pragma[only_bind_into](cc), pragma[only_bind_into](argAp), argAp0,
+      fwdFlowIsEntered(pragma[only_bind_into](call), pragma[only_bind_into](cc),
+        pragma[only_bind_into](argAp), pragma[only_bind_into](argAp0),
         pragma[only_bind_into](config))
     )
   }
@@ -3258,24 +3262,16 @@ class PathNode extends TPathNode {
   /** Gets the associated configuration. */
   Configuration getConfiguration() { none() }
 
-  private predicate isHidden() {
-    hiddenNode(this.(PathNodeImpl).getNodeEx().asNode()) and
-    not this.isSource() and
-    not this instanceof PathNodeSink
-    or
-    this.(PathNodeImpl).getNodeEx() instanceof TNodeImplicitRead
-  }
-
   private PathNode getASuccessorIfHidden() {
-    this.isHidden() and
+    this.(PathNodeImpl).isHidden() and
     result = this.(PathNodeImpl).getASuccessorImpl()
   }
 
   /** Gets a successor of this node, if any. */
   final PathNode getASuccessor() {
     result = this.(PathNodeImpl).getASuccessorImpl().getASuccessorIfHidden*() and
-    not this.isHidden() and
-    not result.isHidden()
+    not this.(PathNodeImpl).isHidden() and
+    not result.(PathNodeImpl).isHidden()
   }
 
   /** Holds if this node is a source. */
@@ -3287,6 +3283,14 @@ abstract private class PathNodeImpl extends PathNode {
 
   abstract NodeEx getNodeEx();
 
+  predicate isHidden() {
+    hiddenNode(this.getNodeEx().asNode()) and
+    not this.isSource() and
+    not this instanceof PathNodeSink
+    or
+    this.getNodeEx() instanceof TNodeImplicitRead
+  }
+
   private string ppAp() {
     this instanceof PathNodeSink and result = ""
     or
@@ -3313,10 +3317,15 @@ abstract private class PathNodeImpl extends PathNode {
 }
 
 /** Holds if `n` can reach a sink. */
-private predicate reach(PathNode n) { n instanceof PathNodeSink or reach(n.getASuccessor()) }
+private predicate directReach(PathNode n) {
+  n instanceof PathNodeSink or directReach(n.getASuccessor())
+}
 
-/** Holds if `n1.getSucc() = n2` and `n2` can reach a sink. */
-private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and reach(n2) }
+/** Holds if `n` can reach a sink or is used in a subpath. */
+private predicate reach(PathNode n) { directReach(n) or Subpaths::retReach(n) }
+
+/** Holds if `n1.getASuccessor() = n2` and `n2` can reach a sink. */
+private predicate pathSucc(PathNode n1, PathNode n2) { n1.getASuccessor() = n2 and directReach(n2) }
 
 private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1, n2)
 
@@ -3325,12 +3334,14 @@ private predicate pathSuccPlus(PathNode n1, PathNode n2) = fastTC(pathSucc/2)(n1
  */
 module PathGraph {
   /** Holds if `(a,b)` is an edge in the graph of data flow path explanations. */
-  query predicate edges(PathNode a, PathNode b) { pathSucc(a, b) }
+  query predicate edges(PathNode a, PathNode b) { a.getASuccessor() = b and reach(b) }
 
   /** Holds if `n` is a node in the graph of data flow path explanations. */
   query predicate nodes(PathNode n, string key, string val) {
     reach(n) and key = "semmle.label" and val = n.toString()
   }
+
+  query predicate subpaths = Subpaths::subpaths/4;
 }
 
 /**
@@ -3622,6 +3633,87 @@ private predicate pathThroughCallable(PathNodeMid mid, NodeEx out, CallContext c
   )
 }
 
+private module Subpaths {
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple and `ret` is determined by
+   * `kind`, `sc`, `apout`, and `innercc`.
+   */
+  pragma[nomagic]
+  private predicate subpaths01(
+    PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
+    NodeEx out, AccessPath apout
+  ) {
+    pathThroughCallable(arg, out, _, pragma[only_bind_into](apout)) and
+    pathIntoCallable(arg, par, _, innercc, sc, _) and
+    paramFlowsThrough(kind, innercc, sc, pragma[only_bind_into](apout), _,
+      unbindConf(arg.getConfiguration()))
+  }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple and `ret` is determined by
+   * `kind`, `sc`, `apout`, and `innercc`.
+   */
+  pragma[nomagic]
+  private predicate subpaths02(
+    PathNode arg, ParamNodeEx par, SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind,
+    NodeEx out, AccessPath apout
+  ) {
+    subpaths01(arg, par, sc, innercc, kind, out, apout) and
+    out.asNode() = kind.getAnOutNode(_)
+  }
+
+  pragma[nomagic]
+  private Configuration getPathNodeConf(PathNode n) { result = n.getConfiguration() }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple.
+   */
+  pragma[nomagic]
+  private predicate subpaths03(
+    PathNode arg, ParamNodeEx par, PathNodeMid ret, NodeEx out, AccessPath apout
+  ) {
+    exists(SummaryCtxSome sc, CallContext innercc, ReturnKindExt kind, RetNodeEx retnode |
+      subpaths02(arg, par, sc, innercc, kind, out, apout) and
+      ret.getNodeEx() = retnode and
+      kind = retnode.getKind() and
+      innercc = ret.getCallContext() and
+      sc = ret.getSummaryCtx() and
+      ret.getConfiguration() = unbindConf(getPathNodeConf(arg)) and
+      apout = ret.getAp() and
+      not ret.isHidden()
+    )
+  }
+
+  /**
+   * Holds if `(arg, par, ret, out)` forms a subpath-tuple, that is, flow through
+   * a subpath between `par` and `ret` with the connecting edges `arg -> par` and
+   * `ret -> out` is summarized as the edge `arg -> out`.
+   */
+  predicate subpaths(PathNode arg, PathNodeImpl par, PathNodeMid ret, PathNodeMid out) {
+    exists(ParamNodeEx p, NodeEx o, AccessPath apout |
+      pragma[only_bind_into](arg).getASuccessor() = par and
+      pragma[only_bind_into](arg).getASuccessor() = out and
+      subpaths03(arg, p, ret, o, apout) and
+      par.getNodeEx() = p and
+      out.getNodeEx() = o and
+      out.getAp() = apout
+    )
+  }
+
+  /**
+   * Holds if `n` can reach a return node in a summarized subpath.
+   */
+  predicate retReach(PathNode n) {
+    subpaths(_, _, n, _)
+    or
+    exists(PathNode mid |
+      retReach(mid) and
+      n.getASuccessor() = mid and
+      not subpaths(_, mid, _, _)
+    )
+  }
+}
+
 /**
  * Holds if data can flow (inter-procedurally) from `source` to `sink`.
  *

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

@@ -786,13 +786,18 @@ private module Cached {
   }
 
   /**
-   * Holds if the call context `call` either improves virtual dispatch in
-   * `callable` or if it allows us to prune unreachable nodes in `callable`.
+   * Holds if the call context `call` improves virtual dispatch in `callable`.
    */
   cached
-  predicate recordDataFlowCallSite(DataFlowCall call, DataFlowCallable callable) {
+  predicate recordDataFlowCallSiteDispatch(DataFlowCall call, DataFlowCallable callable) {
     reducedViableImplInCallContext(_, callable, call)
-    or
+  }
+
+  /**
+   * Holds if the call context `call` allows us to prune unreachable nodes in `callable`.
+   */
+  cached
+  predicate recordDataFlowCallSiteUnreachable(DataFlowCall call, DataFlowCallable callable) {
     exists(Node n | getNodeEnclosingCallable(n) = callable | isUnreachableInCallCached(n, call))
   }
 
@@ -846,6 +851,15 @@ private module Cached {
     TAccessPathFrontSome(AccessPathFront apf)
 }
 
+/**
+ * Holds if the call context `call` either improves virtual dispatch in
+ * `callable` or if it allows us to prune unreachable nodes in `callable`.
+ */
+predicate recordDataFlowCallSite(DataFlowCall call, DataFlowCallable callable) {
+  recordDataFlowCallSiteDispatch(call, callable) or
+  recordDataFlowCallSiteUnreachable(call, callable)
+}
+
 /**
  * A `Node` at which a cast can occur such that the type should be checked.
  */

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

@@ -869,6 +869,9 @@ predicate jumpStep(Node nodeFrom, Node nodeTo) {
     module_export(mv.getScope(), r.getAttributeName(), nodeFrom) and
     nodeTo = r
   )
+  or
+  // Default value for parameter flows to that parameter
+  defaultValueFlowStep(nodeFrom, nodeTo)
 }
 
 /**
@@ -1033,6 +1036,19 @@ predicate kwOverflowStoreStep(CfgNode nodeFrom, DictionaryElementContent c, Node
   )
 }
 
+predicate defaultValueFlowStep(CfgNode nodeFrom, CfgNode nodeTo) {
+  exists(Function f, Parameter p, ParameterDefinition def |
+    // `getArgByName` supports, unlike `getAnArg`, keyword-only parameters
+    p = f.getArgByName(_) and
+    nodeFrom.asExpr() = p.getDefault() and
+    // The following expresses
+    // nodeTo.(ParameterNode).getParameter() = p
+    // without non-monotonic recursion
+    def.getParameter() = p and
+    nodeTo.getNode() = def.getDefiningNode()
+  )
+}
+
 /**
  * Holds if data can flow from `nodeFrom` to `nodeTo` via a read of content `c`.
  */

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

@@ -18,6 +18,10 @@ predicate localFlowStep(Node nodeFrom, Node nodeTo) { simpleLocalFlowStep(nodeFr
 predicate localFlow(Node source, Node sink) { localFlowStep*(source, sink) }
 
 /**
+ * DEPRECATED. Use the API graphs library (`semmle.python.ApiGraphs`) instead.
+ *
+ * For a drop-in replacement, use `API::moduleImport(name).getAUse()`.
+ *
  * Gets a `Node` that refers to the module referenced by `name`.
  * Note that for the statement `import pkg.mod`, the new variable introduced is `pkg` that is a
  * reference to the module `pkg`.
@@ -37,7 +41,7 @@ predicate localFlow(Node source, Node sink) { localFlowStep*(source, sink) }
  *   `mypkg/foo.py` but the variable `foo` containing `42` -- however, `import mypkg.foo` will always cause `mypkg.foo`
  *   to refer to the module.
  */
-Node importNode(string name) {
+deprecated Node importNode(string name) {
   exists(Variable var, Import imp, Alias alias |
     alias = imp.getAName() and
     alias.getAsname() = var.getAStore() and

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

@@ -104,26 +104,20 @@ class LocalSourceNode extends Node {
   }
 
   /**
-   * DEPRECATED. Use `TypeTrackingNode::track` instead.
-   *
    * Gets a node that this node may flow to using one heap and/or interprocedural step.
    *
    * See `TypeTracker` for more details about how to use this.
    */
   pragma[inline]
-  deprecated LocalSourceNode track(TypeTracker t2, TypeTracker t) { t = t2.step(this, result) }
+  LocalSourceNode track(TypeTracker t2, TypeTracker t) { t = t2.step(this, result) }
 
   /**
-   * DEPRECATED. Use `TypeTrackingNode::backtrack` instead.
-   *
    * Gets a node that may flow into this one using one heap and/or interprocedural step.
    *
    * See `TypeBackTracker` for more details about how to use this.
    */
   pragma[inline]
-  deprecated LocalSourceNode backtrack(TypeBackTracker t2, TypeBackTracker t) {
-    t2 = t.step(result, this)
-  }
+  LocalSourceNode backtrack(TypeBackTracker t2, TypeBackTracker t) { t2 = t.step(result, this) }
 }
 
 /**
@@ -131,40 +125,46 @@ class LocalSourceNode extends Node {
  *
  * All steps made during type tracking should be between instances of this class.
  */
-class TypeTrackingNode extends Node {
-  TypeTrackingNode() {
-    this instanceof LocalSourceNode
-    or
-    this instanceof ModuleVariableNode
+class TypeTrackingNode = LocalSourceNode;
+
+/** Temporary holding ground for the `TypeTrackingNode` class. */
+private module FutureWork {
+  class FutureTypeTrackingNode extends Node {
+    FutureTypeTrackingNode() {
+      this instanceof LocalSourceNode
+      or
+      this instanceof ModuleVariableNode
+    }
+
+    /**
+     * Holds if this node can flow to `nodeTo` in one or more local flow steps.
+     *
+     * For `ModuleVariableNode`s, the only "local" step is to the node itself.
+     * For `LocalSourceNode`s, this is the usual notion of local flow.
+     */
+    pragma[inline]
+    predicate flowsTo(Node node) {
+      this instanceof ModuleVariableNode and this = node
+      or
+      this.(LocalSourceNode).flowsTo(node)
+    }
+
+    /**
+     * Gets a node that this node may flow to using one heap and/or interprocedural step.
+     *
+     * See `TypeTracker` for more details about how to use this.
+     */
+    pragma[inline]
+    TypeTrackingNode track(TypeTracker t2, TypeTracker t) { t = t2.step(this, result) }
+
+    /**
+     * Gets a node that may flow into this one using one heap and/or interprocedural step.
+     *
+     * See `TypeBackTracker` for more details about how to use this.
+     */
+    pragma[inline]
+    TypeTrackingNode backtrack(TypeBackTracker t2, TypeBackTracker t) { t2 = t.step(result, this) }
   }
-
-  /**
-   * Holds if this node can flow to `nodeTo` in one or more local flow steps.
-   *
-   * For `ModuleVariableNode`s, the only "local" step is to the node itself.
-   * For `LocalSourceNode`s, this is the usual notion of local flow.
-   */
-  predicate flowsTo(Node node) {
-    this instanceof ModuleVariableNode and this = node
-    or
-    this.(LocalSourceNode).flowsTo(node)
-  }
-
-  /**
-   * Gets a node that this node may flow to using one heap and/or interprocedural step.
-   *
-   * See `TypeTracker` for more details about how to use this.
-   */
-  pragma[inline]
-  TypeTrackingNode track(TypeTracker t2, TypeTracker t) { t = t2.step(this, result) }
-
-  /**
-   * Gets a node that may flow into this one using one heap and/or interprocedural step.
-   *
-   * See `TypeBackTracker` for more details about how to use this.
-   */
-  pragma[inline]
-  TypeTrackingNode backtrack(TypeBackTracker t2, TypeBackTracker t) { t2 = t.step(result, this) }
 }
 
 cached
@@ -179,11 +179,21 @@ private module Cached {
     source = sink
     or
     exists(Node second |
-      simpleLocalFlowStep(source, second) and
-      simpleLocalFlowStep*(second, sink)
+      localSourceFlowStep(source, second) and
+      localSourceFlowStep*(second, sink)
     )
   }
 
+  /**
+   * Helper predicate for `hasLocalSource`. Removes any steps go to module variable reads, as these
+   * are already local source nodes in their own right.
+   */
+  cached
+  private predicate localSourceFlowStep(Node nodeFrom, Node nodeTo) {
+    simpleLocalFlowStep(nodeFrom, nodeTo) and
+    not nodeTo = any(ModuleVariableNode v).getARead()
+  }
+
   /**
    * Holds if `base` flows to the base of `ref` and `ref` has attribute name `attr`.
    */

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

@@ -1,6 +1,20 @@
-import python
-import semmle.python.dataflow.new.DataFlow
+/**
+ * INTERNAL: Do not use.
+ *
+ * Provides helper predicates for pretty-printing `DataFlow::Node`s.
+ *
+ * Since these have not been performance optimized, please only use them for
+ * debug-queries or in tests.
+ */
 
+private import python
+private import semmle.python.dataflow.new.DataFlow
+
+/**
+ * INTERNAL: Do not use.
+ *
+ * Gets the pretty-printed version of the Expr `e`.
+ */
 string prettyExpr(Expr e) {
   not e instanceof Num and
   not e instanceof StrConst and
@@ -27,7 +41,9 @@ string prettyExpr(Expr e) {
 }
 
 /**
- * Gets pretty-printed version of the DataFlow::Node `node`
+ * INTERNAL: Do not use.
+ *
+ * Gets the pretty-printed version of the DataFlow::Node `node`
  */
 bindingset[node]
 string prettyNode(DataFlow::Node node) {
@@ -35,7 +51,9 @@ string prettyNode(DataFlow::Node node) {
 }
 
 /**
- * Gets pretty-printed version of the DataFlow::Node `node`, that is suitable for use
+ * INTERNAL: Do not use.
+ *
+ * Gets the pretty-printed version of the DataFlow::Node `node`, that is suitable for use
  * with `TestUtilities.InlineExpectationsTest` (that is, no spaces unless required).
  */
 bindingset[node]

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

@@ -46,9 +46,13 @@ private module Cached {
     or
     copyStep(nodeFrom, nodeTo)
     or
-    forStep(nodeFrom, nodeTo)
+    DataFlowPrivate::forReadStep(nodeFrom, _, nodeTo)
     or
-    unpackingAssignmentStep(nodeFrom, nodeTo)
+    DataFlowPrivate::iterableUnpackingReadStep(nodeFrom, _, nodeTo)
+    or
+    DataFlowPrivate::iterableUnpackingStoreStep(nodeFrom, _, nodeTo)
+    or
+    awaitStep(nodeFrom, nodeTo)
   }
 }
 
@@ -201,26 +205,9 @@ predicate copyStep(DataFlow::CfgNode nodeFrom, DataFlow::CfgNode nodeTo) {
 }
 
 /**
- * Holds if taint can flow from `nodeFrom` to `nodeTo` with a step related to `for`-iteration,
- * for example `for x in xs`, or `for x,y in points`.
+ * Holds if taint can flow from `nodeFrom` to `nodeTo` with an `await`-step,
+ * such that the whole expression `await x` is tainted if `x` is tainted.
  */
-predicate forStep(DataFlow::CfgNode nodeFrom, DataFlow::EssaNode nodeTo) {
-  exists(EssaNodeDefinition defn, For for |
-    for.getTarget().getAChildNode*() = defn.getDefiningNode().getNode() and
-    nodeTo.getVar() = defn and
-    nodeFrom.asExpr() = for.getIter()
-  )
-}
-
-/**
- * Holds if taint can flow from `nodeFrom` to `nodeTo` with a step related to iterable unpacking.
- * Only handles normal assignment (`x,y = calc_point()`), since `for x,y in points` is handled by `forStep`.
- */
-predicate unpackingAssignmentStep(DataFlow::CfgNode nodeFrom, DataFlow::EssaNode nodeTo) {
-  // `a, b = myiterable` or `head, *tail = myiterable` (only Python 3)
-  exists(MultiAssignmentDefinition defn, Assign assign |
-    assign.getATarget().contains(defn.getDefiningNode().getNode()) and
-    nodeTo.getVar() = defn and
-    nodeFrom.asExpr() = assign.getValue()
-  )
+predicate awaitStep(DataFlow::Node nodeFrom, DataFlow::Node nodeTo) {
+  nodeTo.asExpr().(Await).getValue() = nodeFrom.asExpr()
 }