Crypto: Adding alg value consumers for EVP PKEY for openssl. As part of the additional modeling, updated the generic dataflow source to match JCA with how "EC" is handled as a consumed algorithm for PKEY.

cpp/ql/lib/experimental/quantum/Language.qll

@@ -1,5 +1,5 @@
 private import cpp as Language
-import semmle.code.cpp.dataflow.new.DataFlow
+import semmle.code.cpp.dataflow.new.TaintTracking
 import codeql.quantum.experimental.Model
 
 module CryptoInput implements InputSig<Language::Location> {
@@ -86,6 +86,27 @@ module GenericDataSourceFlowConfig implements DataFlow::ConfigSig {
   }
 }
 
+module GenericDataSourceFlow = TaintTracking::Global<GenericDataSourceFlowConfig>;
+
+private class ConstantDataSource extends Crypto::GenericConstantSourceInstance instanceof Literal {
+  ConstantDataSource() {
+    // TODO: this is an API specific workaround for OpenSSL, as 'EC' is a constant that may be used
+    // where typical algorithms are specified, but EC specifically means set up a
+    // default curve container, that will later be specified explicitly (or if not a default)
+    // curve is used.
+    this.getValue() != "EC"
+  }
+
+  override DataFlow::Node getOutputNode() { result.asExpr() = this }
+
+  override predicate flowsTo(Crypto::FlowAwareElement other) {
+    // TODO: separate config to avoid blowing up data-flow analysis
+    GenericDataSourceFlow::flow(this.getOutputNode(), other.getInputNode())
+  }
+
+  override string getAdditionalDescription() { result = this.toString() }
+}
+
 module ArtifactUniversalFlowConfig implements DataFlow::ConfigSig {
   predicate isSource(DataFlow::Node source) {
     source = any(Crypto::ArtifactInstance artifact).getOutputNode()

cpp/ql/lib/experimental/quantum/OpenSSL/AlgorithmValueConsumers/OpenSSLAlgorithmValueConsumers.qll

@@ -4,3 +4,4 @@ import DirectAlgorithmValueConsumer
 import PaddingAlgorithmValueConsumer
 import HashAlgorithmValueConsumer
 import EllipticCurveAlgorithmValueConsumer
+import PKeyAlgorithmValueConsumer

cpp/ql/lib/experimental/quantum/OpenSSL/AlgorithmValueConsumers/PKeyAlgorithmValueConsumer.qll

@@ -0,0 +1,57 @@
+import cpp
+private import experimental.quantum.Language
+private import experimental.quantum.OpenSSL.LibraryDetector
+private import experimental.quantum.OpenSSL.AlgorithmInstances.KnownAlgorithmConstants
+private import experimental.quantum.OpenSSL.AlgorithmValueConsumers.OpenSSLAlgorithmValueConsumerBase
+private import experimental.quantum.OpenSSL.AlgorithmInstances.OpenSSLAlgorithmInstances
+
+abstract class PKeyValueConsumer extends OpenSSLAlgorithmValueConsumer { }
+
+class EVPPKeyAlgorithmConsumer extends PKeyValueConsumer {
+  DataFlow::Node valueArgNode;
+  DataFlow::Node resultNode;
+
+  EVPPKeyAlgorithmConsumer() {
+    resultNode.asExpr() = this.(Call) and // in all cases the result is the return
+    isPossibleOpenSSLFunction(this.(Call).getTarget()) and
+    (
+      // NOTE: some of these consumers are themselves key gen operations,
+      // in these cases, the operation will be created separately for the same function.
+      this.(Call).getTarget().getName() in [
+          "EVP_PKEY_CTX_new_id", "EVP_PKEY_new_raw_private_key", "EVP_PKEY_new_raw_public_key",
+          "EVP_PKEY_new_mac_key"
+        ] and
+      valueArgNode.asExpr() = this.(Call).getArgument(0)
+      or
+      this.(Call).getTarget().getName() in [
+          "EVP_PKEY_CTX_new_from_name", "EVP_PKEY_new_raw_private_key_ex",
+          "EVP_PKEY_new_raw_public_key_ex", "EVP_PKEY_CTX_ctrl", "EVP_PKEY_CTX_set_group_name"
+        ] and
+      valueArgNode.asExpr() = this.(Call).getArgument(1)
+      or
+      // argInd 2 is 'type' which can be RSA, or EC
+      // if RSA argInd 3 is the key size, else if EC argInd 3 is the curve name
+      // In all other cases there is no argInd 3, and argInd 2 is the algorithm.
+      // Since this is a key gen operation, handling the key size should be handled
+      // when the operation is again modeled as a key gen operation.
+      this.(Call).getTarget().getName() = "EVP_PKEY_Q_keygen" and
+      (
+        // Ellipitic curve case
+        // If the argInd 3 is a derived type (pointer or array) then assume it is a curve name
+        if this.(Call).getArgument(3).getType().getUnderlyingType() instanceof DerivedType
+        then valueArgNode.asExpr() = this.(Call).getArgument(3)
+        else
+          // All other cases
+          valueArgNode.asExpr() = this.(Call).getArgument(2)
+      )
+    )
+  }
+
+  override Crypto::AlgorithmInstance getAKnownAlgorithmSource() {
+    exists(OpenSSLAlgorithmInstance i | i.getAVC() = this and result = i)
+  }
+
+  override DataFlow::Node getResultNode() { result = resultNode }
+
+  override Crypto::ConsumerInputDataFlowNode getInputNode() { result = valueArgNode }
+}