Python: preserve sensitive configuration key precision

python/ql/lib/change-notes/2026-08-20-sensitive-configuration-keys.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The `py/clear-text-logging-sensitive-data`, `py/clear-text-storage-sensitive-data`, and `py/weak-sensitive-data-hashing` queries no longer propagate sensitive data through resolved configuration lookups whose only value selectors are concrete, non-sensitive `section` and `key` arguments. Calls with sensitive or dynamic names, or with additional value arguments, remain unchanged.

python/ql/lib/semmle/python/dataflow/new/SensitiveDataSources.qll

@@ -6,6 +6,7 @@
 private import python
 private import semmle.python.controlflow.internal.Cfg as Cfg
 private import semmle.python.dataflow.new.DataFlow
+private import semmle.python.dataflow.new.internal.DataFlowDispatch as DataFlowDispatch
 // Need to import `semmle.python.Frameworks` since frameworks can extend `SensitiveDataSource::Range`
 private import semmle.python.Frameworks
 private import codeql.concepts.internal.SensitiveDataHeuristics as SensitiveDataHeuristics
@@ -84,6 +85,87 @@ private module SensitiveDataModeling {
     sensitiveFunction(DataFlow::TypeTracker::end(), classification).flowsTo(result)
   }
 
+  /** Gets the unique string literal passed to `parameterName`, if all local sources agree. */
+  private string constantArgument(DataFlowDispatch::NormalCall call, string parameterName) {
+    exists(
+      DataFlowDispatch::ArgumentPosition argumentPosition,
+      DataFlowDispatch::ParameterPosition parameterPosition, DataFlow::ArgumentNode argument,
+      DataFlow::LocalSourceNode representative
+    |
+      DataFlowDispatch::parameterMatch(parameterPosition, argumentPosition) and
+      call.getCallable().getParameter(parameterPosition).getParameter().getName() = parameterName and
+      argument = call.getArgument(argumentPosition) and
+      representative = argument.getALocalSource() and
+      result = representative.asExpr().(StringLiteral).getText() and
+      forall(DataFlow::LocalSourceNode source | source = argument.getALocalSource() |
+        source.asExpr().(StringLiteral).getText() = result
+      )
+    )
+  }
+
+  private predicate resolvedConfigurationCall(
+    DataFlowDispatch::NormalCall call, string section, string key
+  ) {
+    section = constantArgument(call, "section") and
+    key = constantArgument(call, "key") and
+    not callNameIndicatesSensitiveData(call) and
+    onlyConfigurationSelectorArguments(call)
+  }
+
+  private predicate onlyConfigurationSelectorArguments(DataFlowDispatch::NormalCall call) {
+    forall(DataFlowDispatch::ArgumentPosition argumentPosition |
+      exists(call.getArgument(argumentPosition))
+    |
+      exists(DataFlowDispatch::ParameterPosition parameterPosition |
+        DataFlowDispatch::parameterMatch(parameterPosition, argumentPosition) and
+        (
+          parameterPosition.isSelf()
+          or
+          call.getCallable().getParameter(parameterPosition).getParameter().getName() in [
+              "section", "key"
+            ]
+        )
+      )
+    )
+  }
+
+  private predicate callNameIndicatesSensitiveData(DataFlowDispatch::NormalCall call) {
+    nameIndicatesSensitiveData(call.getCallable().getScope().(Function).getName())
+    or
+    nameIndicatesSensitiveData(call.getNode().(Cfg::CallNode).getFunction().(Cfg::NameNode).getId())
+    or
+    nameIndicatesSensitiveData(call.getNode()
+          .(Cfg::CallNode)
+          .getFunction()
+          .(Cfg::AttrNode)
+          .getName())
+  }
+
+  bindingset[name]
+  private predicate configurationSelectorIndicatesSensitiveData(string name) {
+    // File, path, and URL suffixes do not make configuration selectors safe: they
+    // commonly identify an indirect secret or a value that embeds credentials.
+    name.regexpMatch(maybeSensitiveRegexp(_))
+    or
+    name.regexpMatch("(?is).*(^|[_-])(secret|auth|salt|bearer|key(tab)?|token|cred(ential)?|conn(ect(ion)?)?|"
+        + "backend|dsn|url|uri|args|kwargs)([_-]|$).*")
+  }
+
+  /**
+   * Holds if every resolved target for `node` has concrete `section` and `key`
+   * arguments whose names do not indicate sensitive data.
+   */
+  predicate knownNonSensitiveConfigurationValue(DataFlow::Node node) {
+    exists(DataFlowDispatch::NormalCall call | call.getNode() = node.asCfgNode()) and
+    forall(DataFlowDispatch::NormalCall call | call.getNode() = node.asCfgNode() |
+      exists(string section, string key |
+        resolvedConfigurationCall(call, section, key) and
+        not configurationSelectorIndicatesSensitiveData(section) and
+        not configurationSelectorIndicatesSensitiveData(key)
+      )
+    )
+  }
+
   /**
    * Gets a reference (in local scope) to a string constant that, if used as the key in
    * a lookup, indicates the presence of sensitive data with `classification`.
@@ -336,4 +418,16 @@ private module SensitiveDataModeling {
 
 predicate sensitiveDataExtraStepForCalls = SensitiveDataModeling::extraStepForCalls/2;
 
+/**
+ * Holds if `node` is a resolved configuration lookup whose only inputs are its
+ * receiver and concrete, non-sensitive section and key names.
+ *
+ * This predicate is intended for use as a sensitive-data barrier. It blocks all
+ * flow through the lookup result, so calls with additional value arguments are
+ * deliberately excluded.
+ */
+predicate isKnownNonSensitiveConfigurationLookup(DataFlow::Node node) {
+  SensitiveDataModeling::knownNonSensitiveConfigurationValue(node)
+}
+
 predicate sensitiveLookupStringConst = SensitiveDataModeling::sensitiveLookupStringConst/1;

python/ql/lib/semmle/python/security/dataflow/CleartextLoggingCustomizations.qll

@@ -36,6 +36,10 @@ module CleartextLogging {
    */
   abstract class Sanitizer extends DataFlow::Node { }
 
+  private class KnownNonSensitiveConfigurationLookupSanitizer extends Sanitizer {
+    KnownNonSensitiveConfigurationLookupSanitizer() { isKnownNonSensitiveConfigurationLookup(this) }
+  }
+
   /**
    * A source of sensitive data, considered as a flow source.
    */

python/ql/lib/semmle/python/security/dataflow/CleartextStorageCustomizations.qll

@@ -35,6 +35,10 @@ module CleartextStorage {
    */
   abstract class Sanitizer extends DataFlow::Node { }
 
+  private class KnownNonSensitiveConfigurationLookupSanitizer extends Sanitizer {
+    KnownNonSensitiveConfigurationLookupSanitizer() { isKnownNonSensitiveConfigurationLookup(this) }
+  }
+
   /**
    * A source of sensitive data, considered as a flow source.
    */

python/ql/lib/semmle/python/security/dataflow/WeakSensitiveDataHashingCustomizations.qll

@@ -48,6 +48,10 @@ module NormalHashFunction {
    */
   abstract class Sanitizer extends DataFlow::Node { }
 
+  private class KnownNonSensitiveConfigurationLookupSanitizer extends Sanitizer {
+    KnownNonSensitiveConfigurationLookupSanitizer() { isKnownNonSensitiveConfigurationLookup(this) }
+  }
+
   /**
    * A source of sensitive data, considered as a flow source.
    */
@@ -117,6 +121,10 @@ module ComputationallyExpensiveHashFunction {
    */
   abstract class Sanitizer extends DataFlow::Node { }
 
+  private class KnownNonSensitiveConfigurationLookupSanitizer extends Sanitizer {
+    KnownNonSensitiveConfigurationLookupSanitizer() { isKnownNonSensitiveConfigurationLookup(this) }
+  }
+
   /**
    * A source of passwords, considered as a flow source.
    */

python/ql/test/library-tests/dataflow/sensitive-data/TestSensitiveDataSources.ql

@@ -40,6 +40,8 @@ module SensitiveUseConfig implements DataFlow::ConfigSig {
   predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
     sensitiveDataExtraStepForCalls(node1, node2)
   }
+
+  predicate isBarrier(DataFlow::Node node) { isKnownNonSensitiveConfigurationLookup(node) }
 }
 
 module SensitiveUseFlow = TaintTracking::Global<SensitiveUseConfig>;

python/ql/test/library-tests/dataflow/sensitive-data/test.py

@@ -133,3 +133,66 @@ def call_wrapper(func):
 
 # since we have precise dictionary content, other items of the config are not tainted
 print(_config["sleep_timer"])
+
+
+# ------------------------------------------------------------------------------
+# cross-talk through configuration getters.
+# ------------------------------------------------------------------------------
+
+class Configuration:
+    def _get_secret_option(self, section, key):
+        if self.is_sensitive(section, key):
+            return load_secret_value() # $ SensitiveDataSource=secret
+        return None
+
+    def get(self, section, key, fallback="default"):
+        value = self._get_secret_option(section, key) # $ SensitiveDataSource=secret
+        if value is not None:
+            return value
+        return fallback
+
+    def getlist(self, section, key):
+        return self.get(section, key).split(",")
+
+    def get_mandatory_list_value(self, section, key):
+        return self.getlist(section, key)
+
+
+configuration = Configuration()
+
+executor_name = configuration.get_mandatory_list_value("core", "EXECUTOR")[0]
+print(executor_name)
+
+# A second Airflow-shaped path carries a non-sensitive directory through a helper.
+dags_folder = configuration.get_mandatory_list_value("core", "DAGS_FOLDER")[0]
+
+
+def find_path_from_directory(base_dir_path):
+    print(base_dir_path)
+
+
+find_path_from_directory(dags_folder)
+
+# Concrete sensitive keys remain conservative.
+value2 = configuration.get_mandatory_list_value("database", "PASSWORD")[0]
+print(value2) # $ SensitiveUse=secret
+
+# Configuration key names that can hold or locate secrets remain conservative.
+value_with_key_suffix = configuration.get_mandatory_list_value("crypto", "FERNET_KEY")[0]
+print(value_with_key_suffix) # $ SensitiveUse=secret
+
+value_with_path_suffix = configuration.get_mandatory_list_value("smtp", "PASSWORD_FILE")[0]
+print(value_with_path_suffix) # $ SensitiveUse=secret
+
+# Dynamic keys remain conservative.
+dynamic_key = get_key()
+dynamic_value = configuration.get_mandatory_list_value("core", dynamic_key)[0]
+print(dynamic_value) # $ SensitiveUse=secret
+
+# A sensitive callee name remains a source even with non-sensitive selector names.
+value3 = configuration._get_secret_option("core", "EXECUTOR") # $ SensitiveDataSource=secret
+print(value3) # $ SensitiveUse=secret
+
+# Additional value arguments prevent the call result from becoming a barrier.
+value4 = configuration.get("core", "EXECUTOR", get_password()) # $ SensitiveDataSource=password
+print(value4) # $ SensitiveUse=password SensitiveUse=secret