Crypto: Changing fixed key size for the key gen operation for EC key gen to be none, and rely implicitly on the connected algorithm length. (+1 squashed commits) (+1 squashed commits)

Squashed commits:

[b7cd7ba] Crypto: Modeled EC key gen for openssl. (+1 squashed commits)

Author: bdrodes

cpp/ql/lib/experimental/quantum/OpenSSL/AlgorithmInstances/EllipticCurveAlgorithmInstance.qll

@@ -35,8 +35,11 @@ class KnownOpenSSLEllipticCurveConstantAlgorithmInstance extends OpenSSLAlgorith
   override string getRawEllipticCurveName() { result = this.(Literal).getValue().toString() }
 
   override Crypto::TEllipticCurveType getEllipticCurveType() {
-    Crypto::ellipticCurveNameToKeySizeAndFamilyMapping(this.(KnownOpenSSLEllipticCurveAlgorithmConstant)
-          .getNormalizedName(), _, result)
+    Crypto::ellipticCurveNameToKeySizeAndFamilyMapping(this.getParsedEllipticCurveName(), _, result)
+  }
+
+  override string getParsedEllipticCurveName() {
+    result = this.(KnownOpenSSLEllipticCurveAlgorithmConstant).getNormalizedName()
   }
 
   override int getKeySize() {

cpp/ql/lib/experimental/quantum/OpenSSL/Operations/ECKeyGenOperation.qll

@@ -0,0 +1,65 @@
+private import experimental.quantum.Language
+private import experimental.quantum.OpenSSL.LibraryDetector
+private import experimental.quantum.OpenSSL.CtxFlow as CTXFlow
+private import OpenSSLOperationBase
+private import experimental.quantum.OpenSSL.AlgorithmValueConsumers.OpenSSLAlgorithmValueConsumers
+private import semmle.code.cpp.dataflow.new.DataFlow
+
+private module AlgGetterToAlgConsumerConfig implements DataFlow::ConfigSig {
+  predicate isSource(DataFlow::Node source) {
+    exists(OpenSSLAlgorithmValueConsumer c | c.getResultNode() = source)
+  }
+
+  predicate isSink(DataFlow::Node sink) {
+    exists(ECKeyGenOperation c | c.getAlgorithmArg() = sink.asExpr())
+  }
+}
+
+private module AlgGetterToAlgConsumerFlow = DataFlow::Global<AlgGetterToAlgConsumerConfig>;
+
+class ECKeyGenOperation extends OpenSSLOperation, Crypto::KeyGenerationOperationInstance {
+  ECKeyGenOperation() {
+    this.(Call).getTarget().getName() = "EC_KEY_generate_key" and
+    isPossibleOpenSSLFunction(this.(Call).getTarget())
+  }
+
+  override Expr getOutputArg() {
+    result = this.(Call) // return value of call
+  }
+
+  Expr getAlgorithmArg() { result = this.(Call).getArgument(0) }
+
+  override Expr getInputArg() {
+    // there is no 'input', in the sense that no data is being manipualted by the operation.
+    // There is an input of an algorithm, but that is not the intention of the operation input arg.
+    none()
+  }
+
+  override Crypto::KeyArtifactType getOutputKeyType() { result = Crypto::TAsymmetricKeyType() }
+
+  override Crypto::ArtifactOutputDataFlowNode getOutputKeyArtifact() {
+    result = this.getOutputNode()
+  }
+
+  override Crypto::AlgorithmValueConsumer getAnAlgorithmValueConsumer() {
+    AlgGetterToAlgConsumerFlow::flow(result.(OpenSSLAlgorithmValueConsumer).getResultNode(),
+      DataFlow::exprNode(this.getAlgorithmArg()))
+  }
+
+  override Crypto::ConsumerInputDataFlowNode getKeySizeConsumer() {
+    none() // no explicit key size, inferred from algorithm
+  }
+
+  override int getKeySizeFixed() {
+    none()
+    // TODO: marked as none as the operation itself has no key size, it
+    // comes from the algorithm source, but note we could grab the
+    // algorithm source and get the key size (see below).
+    // We may need to reconsider what is the best approach here.
+    // result =
+    //   this.getAnAlgorithmValueConsumer()
+    //       .getAKnownAlgorithmSource()
+    //       .(Crypto::EllipticCurveInstance)
+    //       .getKeySize()
+  }
+}

cpp/ql/lib/experimental/quantum/OpenSSL/Operations/OpenSSLOperations.qll

@@ -1,3 +1,4 @@
 import OpenSSLOperationBase
 import EVPCipherOperation
 import EVPHashOperation
+import ECKeyGenOperation