Crypto: OperationStep overhaul to account for errors and missing interproc flow.

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

@@ -14,8 +14,8 @@ module CryptoInput implements InputSig<Language::Location> {
     result = node.asExpr() or
     result = node.asParameter() or
     result = node.asVariable() or
-    result = node.asDefiningArgument()
-    // TODO: do we need asIndirectExpr()?
+    result = node.asDefiningArgument() or
+    result = node.asIndirectExpr()
   }
 
   string locationToFileBaseNameAndLineNumberString(Location location) {
@@ -93,7 +93,10 @@ module GenericDataSourceFlow = TaintTracking::Global<GenericDataSourceFlowConfig
 
 private class ConstantDataSource extends Crypto::GenericConstantSourceInstance instanceof OpenSslGenericSourceCandidateLiteral
 {
-  override DataFlow::Node getOutputNode() { result.asExpr() = this }
+  override DataFlow::Node getOutputNode() {
+    // A literal can be a string or an int, so handling both indirect and direct cases
+    [result.asIndirectExpr(), result.asExpr()] = this
+  }
 
   override predicate flowsTo(Crypto::FlowAwareElement other) {
     // TODO: separate config to avoid blowing up data-flow analysis

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

@@ -12,7 +12,7 @@ class EvpCipherAlgorithmValueConsumer extends CipherAlgorithmValueConsumer {
   DataFlow::Node resultNode;
 
   EvpCipherAlgorithmValueConsumer() {
-    resultNode.asExpr() = this and
+    resultNode.asIndirectExpr() = this and
     (
       this.(Call).getTarget().getName() in [
           "EVP_get_cipherbyname", "EVP_get_cipherbyobj", "EVP_get_cipherbynid"

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

@@ -23,7 +23,7 @@ class DirectAlgorithmValueConsumer extends OpenSslAlgorithmValueConsumer instanc
    */
   override DataFlow::Node getResultNode() {
     this instanceof OpenSslDirectAlgorithmFetchCall and
-    result.asExpr() = this
+    result.asIndirectExpr() = this
     // NOTE: if instanceof OpenSslDirectAlgorithmOperationCall then there is no algorithm generated
     // the algorithm is directly used
   }

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

@@ -12,7 +12,7 @@ class EvpEllipticCurveAlgorithmConsumer extends EllipticCurveValueConsumer {
   DataFlow::Node resultNode;
 
   EvpEllipticCurveAlgorithmConsumer() {
-    resultNode.asExpr() = this.(Call) and // in all cases the result is the return
+    resultNode.asIndirectExpr() = this.(Call) and // in all cases the result is the return
     (
       this.(Call).getTarget().getName() in ["EVP_EC_gen", "EC_KEY_new_by_curve_name"] and
       valueArgNode.asExpr() = this.(Call).getArgument(0)

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

@@ -64,7 +64,7 @@ class EvpDigestAlgorithmValueConsumer extends HashAlgorithmValueConsumer {
   DataFlow::Node resultNode;
 
   EvpDigestAlgorithmValueConsumer() {
-    resultNode.asExpr() = this and
+    resultNode.asIndirectExpr() = this and
     (
       this.(Call).getTarget().getName() in [
           "EVP_get_digestbyname", "EVP_get_digestbynid", "EVP_get_digestbyobj"

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

@@ -11,7 +11,7 @@ class EvpKemAlgorithmValueConsumer extends KemAlgorithmValueConsumer {
   DataFlow::Node resultNode;
 
   EvpKemAlgorithmValueConsumer() {
-    resultNode.asExpr() = this and
+    resultNode.asIndirectExpr() = this and
     (
       this.(Call).getTarget().getName() = "EVP_KEM_fetch" and
       valueArgNode.asExpr() = this.(Call).getArgument(1)

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

@@ -11,7 +11,7 @@ class EvpKeyExchangeAlgorithmValueConsumer extends KeyExchangeAlgorithmValueCons
   DataFlow::Node resultNode;
 
   EvpKeyExchangeAlgorithmValueConsumer() {
-    resultNode.asExpr() = this and
+    resultNode.asIndirectExpr() = this and
     (
       this.(Call).getTarget().getName() = "EVP_KEYEXCH_fetch" and
       valueArgNode.asExpr() = this.(Call).getArgument(1)

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

@@ -11,7 +11,7 @@ class EvpPKeyAlgorithmConsumer extends PKeyValueConsumer {
   DataFlow::Node resultNode;
 
   EvpPKeyAlgorithmConsumer() {
-    resultNode.asExpr() = this.(Call) and // in all cases the result is the return
+    resultNode.asIndirectExpr() = this.(Call) and // in all cases the result is the return
     (
       // NOTE: some of these consumers are themselves key gen operations,
       // in these cases, the operation will be created separately for the same function.

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

@@ -14,7 +14,7 @@ class Evp_PKey_Ctx_set_rsa_padding_AlgorithmValueConsumer extends PaddingAlgorit
   DataFlow::Node resultNode;
 
   Evp_PKey_Ctx_set_rsa_padding_AlgorithmValueConsumer() {
-    resultNode.asExpr() = this.(Call).getArgument(0) and
+    resultNode.asDefiningArgument() = this.(Call).getArgument(0) and
     this.(Call).getTarget().getName() = "EVP_PKEY_CTX_set_rsa_padding" and
     valueArgNode.asExpr() = this.(Call).getArgument(1)
   }

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

@@ -12,7 +12,7 @@ class EvpSignatureAlgorithmValueConsumer extends SignatureAlgorithmValueConsumer
   DataFlow::Node resultNode;
 
   EvpSignatureAlgorithmValueConsumer() {
-    resultNode.asExpr() = this and
+    resultNode.asIndirectExpr() = this and
     (
       // EVP_SIGNATURE
       this.(Call).getTarget().getName() = "EVP_SIGNATURE_fetch" and

cpp/ql/lib/experimental/quantum/OpenSSL/AvcFlow.qll

@@ -13,7 +13,9 @@ module AvcToCallArgConfig implements DataFlow::ConfigSig {
    * Trace to any call accepting the algorithm.
    * NOTE: users must restrict this set to the operations they are interested in.
    */
-  predicate isSink(DataFlow::Node sink) { exists(Call c | c.getAnArgument() = sink.asExpr()) }
+  predicate isSink(DataFlow::Node sink) {
+    exists(Call c | c.getAnArgument() = [sink.asIndirectExpr(), sink.asExpr()])
+  }
 }
 
 module AvcToCallArgFlow = DataFlow::Global<AvcToCallArgConfig>;

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

@@ -15,11 +15,11 @@ abstract class FinalCipherOperationStep extends OperationStep {
  */
 abstract class EvpCipherOperationFinalStep extends FinalCipherOperationStep {
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 }
 
@@ -28,9 +28,9 @@ abstract class EvpCipherOperationFinalStep extends FinalCipherOperationStep {
  */
 abstract class EvpCipherInitializer extends OperationStep {
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and
+    result.asIndirectExpr() = this.getArgument(1) and
     type = PrimaryAlgorithmIO() and
     // Constants that are not equal to zero or
     // non-constants (e.g., variable accesses, which require data-flow to determine the value)
@@ -40,7 +40,7 @@ abstract class EvpCipherInitializer extends OperationStep {
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -127,13 +127,13 @@ class EvpPkeyEncryptDecryptInit extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(1) and type = OsslParamIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -161,7 +161,7 @@ class EvpCipherUpdateCall extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(3) and type = PlaintextIO()
   }
@@ -169,7 +169,7 @@ class EvpCipherUpdateCall extends OperationStep {
   override DataFlow::Node getOutput(IOType type) {
     result.asExpr() = this.getArgument(1) and type = CiphertextIO()
     or
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = UpdateStep() }

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

@@ -38,7 +38,9 @@ class EvpNewKeyCtx extends OperationStep instanceof Call {
     type = OsslLibContextIO()
   }
 
-  override DataFlow::Node getOutput(IOType type) { result.asExpr() = this and type = ContextIO() }
+  override DataFlow::Node getOutput(IOType type) {
+    result.asIndirectExpr() = this and type = ContextIO()
+  }
 
   override OperationStepType getStepType() { result = ContextCreationStep() }
 }
@@ -52,13 +54,13 @@ class EvpCtxSetEcParamgenCurveNidInitializer extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = PrimaryAlgorithmIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = PrimaryAlgorithmIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -102,7 +104,7 @@ class EvpCtxSetHashInitializer extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(1) and
     type = HashAlgorithmIO() and
@@ -115,7 +117,7 @@ class EvpCtxSetHashInitializer extends OperationStep {
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -134,13 +136,13 @@ class EvpCtxSetKeySizeInitializer extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(1) and type = KeySizeIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -150,7 +152,7 @@ class EvpCtxSetMacKeyInitializer extends OperationStep {
   EvpCtxSetMacKeyInitializer() { this.getTarget().getName() = "EVP_PKEY_CTX_set_mac_key" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(2) and type = KeySizeIO()
     or
@@ -159,7 +161,7 @@ class EvpCtxSetMacKeyInitializer extends OperationStep {
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -171,13 +173,13 @@ class EvpCtxSetPaddingInitializer extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(1) and type = PaddingAlgorithmIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -189,13 +191,13 @@ class EvpCtxSetSaltLengthInitializer extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(1) and type = SaltLengthIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }

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

@@ -25,13 +25,13 @@ class EvpDigestInitVariantCalls extends OperationStep instanceof Call {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = PrimaryAlgorithmIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = PrimaryAlgorithmIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and
+    result.asDefiningArgument() = this.getArgument(0) and
     type = ContextIO()
   }
 
@@ -45,13 +45,13 @@ class EvpDigestUpdateCall extends OperationStep instanceof Call {
   EvpDigestUpdateCall() { this.getTarget().getName() = "EVP_DigestUpdate" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(1) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and
+    result.asDefiningArgument() = this.getArgument(0) and
     type = ContextIO()
   }
 
@@ -66,15 +66,15 @@ class EvpQDigestOperation extends FinalDigestOperation instanceof Call {
   EvpQDigestOperation() { this.getTarget().getName() = "EVP_Q_digest" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(1) and type = PrimaryAlgorithmIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = PrimaryAlgorithmIO()
     or
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this.getArgument(3) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and
+    result.asDefiningArgument() = this.getArgument(0) and
     type = ContextIO()
     or
     result.asDefiningArgument() = this.getArgument(5) and type = DigestIO()
@@ -85,7 +85,7 @@ class EvpDigestOperation extends FinalDigestOperation instanceof Call {
   EvpDigestOperation() { this.getTarget().getName() = "EVP_Digest" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(4) and type = PrimaryAlgorithmIO()
+    result.asIndirectExpr() = this.getArgument(4) and type = PrimaryAlgorithmIO()
     or
     result.asExpr() = this.getArgument(0) and type = PlaintextIO()
   }
@@ -104,14 +104,15 @@ class EvpDigestFinalCall extends FinalDigestOperation instanceof Call {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and
+    result.asDefiningArgument() = this.getArgument(0) and
     type = ContextIO()
     or
     result.asDefiningArgument() = this.getArgument(1) and type = DigestIO()
+    //result.(DataFlow::PostUpdateNode).getPreUpdateNode().asExpr() = this.getArgument(1)
   }
 }
 

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

@@ -13,7 +13,7 @@ class ECKeyGen extends OperationStep instanceof Call {
   ECKeyGen() { this.(Call).getTarget().getName() = "EC_KEY_generate_key" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.(Call).getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) { result.asExpr() = this and type = KeyIO() }
@@ -33,11 +33,11 @@ class EvpKeyGenInitialize extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -57,13 +57,13 @@ class EvpPKeyQKeyGen extends KeyGenFinalOperationStep instanceof Call {
   EvpPKeyQKeyGen() { this.getTarget().getName() = "EVP_PKEY_Q_keygen" }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
     result.asExpr() = this and type = KeyIO()
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     // When arg 3 is a derived type, it is a curve name, otherwise it is a key size for RSA if provided
     // and arg 2 is the algorithm type
@@ -120,7 +120,7 @@ class RsaGenerateKeyEx extends KeyGenFinalOperationStep instanceof Call {
   override DataFlow::Node getInput(IOType type) {
     // arg 0 comes in as a blank RSA key, which we consider a context,
     // on output it is considered a key
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
   }
 }
 
@@ -131,13 +131,13 @@ class EvpPkeyGen extends KeyGenFinalOperationStep instanceof Call {
   EvpPkeyGen() { this.getTarget().getName() in ["EVP_PKEY_generate", "EVP_PKEY_keygen"] }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
     result.asDefiningArgument() = this.getArgument(1) and type = KeyIO()
     or
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 }
 
@@ -158,7 +158,6 @@ class EvpNewMacKey extends KeyGenFinalOperationStep {
   override DataFlow::Node getOutput(IOType type) { result.asExpr() = this and type = KeyIO() }
 }
 
-
 /// TODO: https://docs.openssl.org/3.0/man3/EVP_PKEY_new/#synopsis
 /**
  * An `KeyGenerationOperationInstance` for the for all key gen final operation steps.

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

@@ -198,8 +198,7 @@ abstract class OperationStep extends Call {
    * If `sink` is `this`, then this holds true.
    */
   predicate flowsToOperationStep(OperationStep sink) {
-    sink = this or
-    OperationStepFlow::flow(this.getAnOutput(), sink.getAnInput())
+    OperationStepFlow::flow(this.getAnOutput(), [sink.getAnInput(), sink.getAnOutput()])
   }
 
   /**
@@ -207,8 +206,7 @@ abstract class OperationStep extends Call {
    * If `source` is `this`, then this holds true.
    */
   predicate flowsFromOperationStep(OperationStep source) {
-    source = this or
-    OperationStepFlow::flow(source.getAnOutput(), this.getAnInput())
+    OperationStepFlow::flow(source.getAnOutput(), [this.getAnInput(), this.getAnOutput()])
   }
 
   /**
@@ -226,11 +224,22 @@ abstract class OperationStep extends Call {
    * the operation allows for multiple inputs (like plaintext for cipher update calls before final).
    */
   OperationStep getDominatingInitializersToStep(IOType type) {
-    result.flowsToOperationStep(this) and
+    //exists(IOType sinkInType |
+    //sinkInType = ContextIO() or sinkInType = type |
+    result.flowsToOperationStep(this) and //, sinkInType)
+    //)
     result.setsValue(type) and
     (
       // Do not consider a 'reset' to occur on updates
-      result.getStepType() = UpdateStep()
+      // but only for resets that are part of the same update/finalize
+      // progression (e.g., an update for an unrelated finalize is ignored)
+      result.getStepType() = UpdateStep() and
+      not exists(OperationStep op |
+        result.flowsToOperationStep(op) and
+        op.flowsToOperationStep(this) and
+        op != this and
+        op.getStepType() = FinalStep()
+      )
       or
       not exists(OperationStep reset |
         result != reset and
@@ -269,20 +278,22 @@ abstract class OperationStep extends Call {
   Crypto::AlgorithmValueConsumer getPrimaryAlgorithmValueConsumer() {
     this instanceof Crypto::AlgorithmValueConsumer and result = this
     or
-    exists(DataFlow::Node src, DataFlow::Node sink, IOType t, OperationStep avcConsumingPred |
-      (t = PrimaryAlgorithmIO() or t = ContextIO() or t = KeyIO()) and
+    exists(
+      DataFlow::Node src, DataFlow::Node sink, IOType srcIntype, OperationStep avcConsumingPred
+    |
+      (srcIntype = ContextIO() or srcIntype = PrimaryAlgorithmIO() or srcIntype = KeyIO()) and
       avcConsumingPred.flowsToOperationStep(this) and
-      src.asExpr() = result and
-      sink = avcConsumingPred.getInput(t) and
+      src.asIndirectExpr() = result and
+      sink = avcConsumingPred.getInput(srcIntype) and
       AvcToOperationStepFlow::flow(src, sink) and
       (
         // Case 1: the avcConsumingPred step is a dominating primary algorithm initialization step
         // or dominating key initialization step
-        (t = PrimaryAlgorithmIO() or t = KeyIO()) and
-        avcConsumingPred = this.getDominatingInitializersToStep(t)
+        (srcIntype = PrimaryAlgorithmIO() or srcIntype = KeyIO()) and
+        avcConsumingPred = this.getDominatingInitializersToStep(srcIntype)
         or
         // Case 2: the pred is a context input
-        t = ContextIO()
+        srcIntype = ContextIO()
       )
     )
   }
@@ -297,7 +308,7 @@ abstract class OperationStep extends Call {
     or
     exists(DataFlow::Node src, DataFlow::Node sink |
       AvcToOperationStepFlow::flow(src, sink) and
-      src.asExpr() = result and
+      src.asIndirectExpr() = result and
       sink = this.getInput(type)
     )
   }
@@ -375,7 +386,7 @@ private class CtxCopyOutArgCall extends CtxPassThroughCall {
 
   CtxCopyOutArgCall() {
     this.getTarget().getName().toLowerCase().matches("%copy%") and
-    n1.asExpr() = this.getAnArgument() and
+    n1.asIndirectExpr() = this.getAnArgument() and
     n1.getType() instanceof CtxType and
     n2.asDefiningArgument() = this.getAnArgument() and
     n2.getType() instanceof CtxType and
@@ -396,13 +407,13 @@ private class CtxCopyReturnCall extends CtxPassThroughCall, CtxPointerExpr {
 
   CtxCopyReturnCall() {
     this.getTarget().getName().toLowerCase().matches("%dup%") and
-    n1.asExpr() = this.getAnArgument() and
+    n1.asIndirectExpr() = this.getAnArgument() and
     n1.getType() instanceof CtxType
   }
 
   override DataFlow::Node getNode1() { result = n1 }
 
-  override DataFlow::Node getNode2() { result.asExpr() = this }
+  override DataFlow::Node getNode2() { result.asIndirectExpr() = this }
 }
 
 // TODO: is this still needed? It appears to be (tests fail without it) but
@@ -422,11 +433,7 @@ private class CtxParamGenCall extends CtxPassThroughCall {
   CtxParamGenCall() {
     this.getTarget().getName() = "EVP_PKEY_paramgen" and
     n1.asExpr() = this.getArgument(0) and
-    (
-      n2.asExpr() = this.getArgument(1)
-      or
-      n2.asDefiningArgument() = this.getArgument(1)
-    )
+    n2.asDefiningArgument() = this.getArgument(1)
   }
 
   override DataFlow::Node getNode1() { result = n1 }
@@ -453,15 +460,28 @@ module OperationStepFlowConfig implements DataFlow::ConfigSig {
   }
 
   predicate isBarrier(DataFlow::Node node) {
-    exists(CtxClearCall c | c.getAnArgument() = node.asExpr())
+    exists(CtxClearCall c | c.getAnArgument() = [node.asExpr(), node.asIndirectExpr()])
   }
 
   predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
     exists(CtxPassThroughCall c | c.getNode1() = node1 and c.getNode2() = node2)
     or
-    // Flow out through all outputs from an operation step if more than one output
-    // is defined.
-    exists(OperationStep s | s.getAnInput() = node1 and s.getAnOutput() = node2)
+    // Flow only through context and key inputs and outputs
+    // keys and context generally hold unifying context that link multiple steps
+    exists(OperationStep s, IOType inType, IOType outType |
+      (
+        inType = ContextIO()
+        or
+        inType = KeyIO()
+      ) and
+      (
+        outType = ContextIO()
+        or
+        outType = KeyIO()
+      ) and
+      s.getInput(inType) = node1 and
+      s.getOutput(outType) = node2
+    )
     // TODO: consideration for additional alises defined as follows:
     // if an output from an operation step itself flows from the output of another operation step
     // then the source of that flow's outputs (all of them) are potential aliases
@@ -481,7 +501,7 @@ module AvcToOperationStepFlowConfig implements DataFlow::ConfigSig {
   predicate isSink(DataFlow::Node sink) { exists(OperationStep s | s.getAnInput() = sink) }
 
   predicate isBarrier(DataFlow::Node node) {
-    exists(CtxClearCall c | c.getAnArgument() = node.asExpr())
+    exists(CtxClearCall c | c.getAnArgument() = [node.asExpr(), node.asIndirectExpr()])
   }
 
   /**

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

@@ -37,36 +37,32 @@ class EvpSignatureDigestInitializer extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     this.getTarget().getName() = "EVP_DigestSignInit_ex" and
-    result.asExpr() = this.getArgument(3) and
+    result.asIndirectExpr() = this.getArgument(3) and
     type = OsslLibContextIO()
     or
-    result.asExpr() = this.getArgument(2) and type = HashAlgorithmIO()
+    result.asIndirectExpr() = this.getArgument(2) and type = HashAlgorithmIO()
     or
     this.getTarget().getName() = "EVP_DigestSignInit" and
-    result.asExpr() = this.getArgument(4) and
+    result.asIndirectExpr() = this.getArgument(4) and
     type = KeyIO()
     or
     this.getTarget().getName() = "EVP_DigestSignInit_ex" and
-    result.asExpr() = this.getArgument(5) and
+    result.asIndirectExpr() = this.getArgument(5) and
     type = KeyIO()
     or
     this.getTarget().getName() = "EVP_DigestSignInit_ex" and
-    result.asExpr() = this.getArgument(6) and
+    result.asIndirectExpr() = this.getArgument(6) and
     type = OsslParamIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
     // EVP_PKEY_CTX
-    result.asExpr() = this.getArgument(1) and type = ContextIO()
-    or
-    this.getTarget().getName() = "EVP_DigestSignInit_ex" and
-    result.asExpr() = this.getArgument(6) and
-    type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(1) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -79,13 +75,13 @@ class EvpSignInit extends OperationStep {
   EvpSignInit() { this.getTarget().getName() in ["EVP_SignInit", "EVP_SignInit_ex"] }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = HashAlgorithmIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = HashAlgorithmIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -107,22 +103,22 @@ class EvpPkeySignInit extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     this.getTarget().getName() in ["EVP_PKEY_sign_init_ex2", "EVP_PKEY_sign_message_init"] and
-    result.asExpr() = this.getArgument(1) and
+    result.asIndirectExpr() = this.getArgument(1) and
     type = PrimaryAlgorithmIO()
     or
     this.getTarget().getName() = "EVP_PKEY_sign_init_ex" and
-    result.asExpr() = this.getArgument(1) and
+    result.asIndirectExpr() = this.getArgument(1) and
     type = OsslParamIO()
     or
     // Argument 2 (0 based) only exists for EVP_PKEY_sign_init_ex2 and EVP_PKEY_sign_message_init
-    result.asExpr() = this.getArgument(2) and type = OsslParamIO()
+    result.asIndirectExpr() = this.getArgument(2) and type = OsslParamIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -139,13 +135,13 @@ class EvpSignatureUpdateCall extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = PlaintextIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = UpdateStep() }
@@ -158,19 +154,21 @@ class EvpSignFinal extends SignatureFinalOperation {
   EvpSignFinal() { this.getTarget().getName() in ["EVP_SignFinal_ex", "EVP_SignFinal"] }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(3) and type = KeyIO()
+    result.asIndirectExpr() = this.getArgument(3) and type = KeyIO()
     or
     // params above 3 (0-based) only exist for EVP_SignFinal_ex
-    result.asExpr() = this.getArgument(4) and
+    result.asIndirectExpr() = this.getArgument(4) and
     type = OsslLibContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asDefiningArgument() = this.getArgument(1) and type = SignatureIO()
+    or
+    result.asDefiningArgument() = this.getArgument(2) and type = SignatureSizeIO()
   }
 }
 
@@ -181,15 +179,15 @@ class EvpPkeySign extends SignatureFinalOperation {
   EvpPkeySign() { this.getTarget().getName() = "EVP_PKEY_sign" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(3) and type = PlaintextIO()
+    result.asIndirectExpr() = this.getArgument(3) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asDefiningArgument() = this.getArgument(1) and type = SignatureIO()
   }
 }
 
@@ -201,15 +199,15 @@ class EvpDigestSign extends SignatureOrMacFinalOperation {
   EvpDigestSign() { this.getTarget().getName() = "EVP_DigestSign" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(3) and type = PlaintextIO()
+    result.asIndirectExpr() = this.getArgument(3) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asDefiningArgument() = this.getArgument(1) and type = SignatureIO()
   }
 }
 
@@ -220,13 +218,15 @@ class EvpPkeySignFinal extends SignatureFinalOperation {
   EvpPkeySignFinal() { this.getTarget().getName() = "EVP_PKEY_sign_message_final" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asDefiningArgument() = this.getArgument(1) and type = SignatureIO()
+    or
+    result.asExpr() = this.getArgument(2) and type = SignatureSizeIO()
   }
 }
 
@@ -238,13 +238,13 @@ class EvpDigestSignFinal extends SignatureOrMacFinalOperation {
   EvpDigestSignFinal() { this.getTarget().getName() = "EVP_DigestSignFinal" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asDefiningArgument() = this.getArgument(1) and type = SignatureIO()
   }
 
   override OperationStepType getStepType() { result = FinalStep() }
@@ -259,31 +259,31 @@ class EvpDigestVerifyInit extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(2) and type = HashAlgorithmIO()
+    result.asIndirectExpr() = this.getArgument(2) and type = HashAlgorithmIO()
     or
     this.getTarget().getName() = "EVP_DigestVerifyInit_ex" and
-    result.asExpr() = this.getArgument(3) and
+    result.asIndirectExpr() = this.getArgument(3) and
     type = OsslLibContextIO()
     or
     this.getTarget().getName() = "EVP_DigestVerifyInit_ex" and
-    result.asExpr() = this.getArgument(5) and
+    result.asIndirectExpr() = this.getArgument(5) and
     type = KeyIO()
     or
     this.getTarget().getName() = "EVP_DigestVerifyInit" and
-    result.asExpr() = this.getArgument(4) and
+    result.asIndirectExpr() = this.getArgument(4) and
     type = KeyIO()
     or
     this.getTarget().getName() = "EVP_DigestVerifyInit_ex" and
-    result.asExpr() = this.getArgument(6) and
+    result.asIndirectExpr() = this.getArgument(6) and
     type = OsslParamIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(1) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -296,13 +296,13 @@ class EvpDigestVerifyUpdate extends OperationStep {
   EvpDigestVerifyUpdate() { this.getTarget().getName() = "EVP_DigestVerifyUpdate" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = PlaintextIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = UpdateStep() }
@@ -315,13 +315,13 @@ class EvpDigestVerifyFinal extends SignatureFinalOperation {
   EvpDigestVerifyFinal() { this.getTarget().getName() = "EVP_DigestVerifyFinal" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = SignatureIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 }
 
@@ -332,15 +332,15 @@ class EvpDigestVerify extends SignatureFinalOperation {
   EvpDigestVerify() { this.getTarget().getName() = "EVP_DigestVerify" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = SignatureIO()
     or
-    result.asExpr() = this.getArgument(3) and type = PlaintextIO()
+    result.asIndirectExpr() = this.getArgument(3) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 }
 
@@ -358,23 +358,23 @@ class EvpVerifyInit extends OperationStep {
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
     this.getTarget().getName() = "EVP_PKEY_verify_init_ex" and
-    result.asExpr() = this.getArgument(1) and
+    result.asIndirectExpr() = this.getArgument(1) and
     type = OsslParamIO()
     or
     this.getTarget().getName() in ["EVP_PKEY_verify_init_ex2", "EVP_PKEY_verify_message_init"] and
-    result.asExpr() = this.getArgument(1) and
+    result.asIndirectExpr() = this.getArgument(1) and
     type = PrimaryAlgorithmIO()
     or
     this.getTarget().getName() in ["EVP_PKEY_verify_init_ex2", "EVP_PKEY_verify_message_init"] and
-    result.asExpr() = this.getArgument(2) and
+    result.asIndirectExpr() = this.getArgument(2) and
     type = OsslParamIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -388,15 +388,15 @@ class EvpCtxSetSignatureInitializer extends OperationStep {
   EvpCtxSetSignatureInitializer() { this.getTarget().getName() = "EVP_PKEY_CTX_set_signature" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = SignatureIO()
     or
     result.asExpr() = this.getArgument(2) and type = SignatureSizeIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = InitializerStep() }
@@ -409,15 +409,15 @@ class EvpVerifyMessageUpdate extends OperationStep {
   EvpVerifyMessageUpdate() { this.getTarget().getName() = "EVP_PKEY_verify_message_update" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = PlaintextIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = PlaintextIO()
     or
     result.asExpr() = this.getArgument(2) and type = PlaintextSizeIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 
   override OperationStepType getStepType() { result = UpdateStep() }
@@ -430,11 +430,11 @@ class EvpVerifyMessageFinal extends SignatureFinalOperation {
   EvpVerifyMessageFinal() { this.getTarget().getName() = "EVP_PKEY_verify_message_final" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 }
 
@@ -445,19 +445,19 @@ class EvpVerify extends SignatureFinalOperation {
   EvpVerify() { this.getTarget().getName() = "EVP_PKEY_verify" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asIndirectExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.getArgument(1) and type = SignatureIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = SignatureIO()
     or
     result.asExpr() = this.getArgument(2) and type = SignatureSizeIO()
     or
-    result.asExpr() = this.getArgument(3) and type = PlaintextIO()
+    result.asIndirectExpr() = this.getArgument(3) and type = PlaintextIO()
     or
     result.asExpr() = this.getArgument(4) and type = PlaintextSizeIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
   }
 }
 
@@ -469,25 +469,26 @@ class RsaSign extends SignatureFinalOperation {
   RsaSign() { this.getTarget().getName() in ["RSA_sign", "RSA_verify"] }
 
   override DataFlow::Node getInput(IOType type) {
+    // Arg 0 is an NID (so asExpr not asIndirectExpr)
     result.asExpr() = this.getArgument(0) and type = HashAlgorithmIO()
     or
-    result.asExpr() = this.getArgument(1) and type = PlaintextIO()
+    result.asIndirectExpr() = this.getArgument(1) and type = PlaintextIO()
     or
     result.asExpr() = this.getArgument(2) and type = PlaintextSizeIO()
     or
     this.getTarget().getName() = "RSA_verify" and
-    result.asExpr() = this.getArgument(3) and
+    result.asIndirectExpr() = this.getArgument(3) and
     type = SignatureIO()
     or
     this.getTarget().getName() = "RSA_verify" and
-    result.asExpr() = this.getArgument(4) and
+    result.asIndirectExpr() = this.getArgument(4) and
     type = SignatureSizeIO()
     or
-    result.asExpr() = this.getArgument(5) and type = KeyIO()
+    result.asIndirectExpr() = this.getArgument(5) and type = KeyIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.getArgument(0) and type = ContextIO()
+    result.asDefiningArgument() = this.getArgument(0) and type = ContextIO()
     or
     this.getTarget().getName() = "RSA_sign" and
     result.asDefiningArgument() = this.getArgument(3) and

cpp/ql/test/experimental/library-tests/quantum/openssl_signature.c

@@ -363,10 +363,10 @@ cleanup:
     return ret;
 }
 
-/* =============================================================================
- * LOW-LEVEL RSA API - Algorithm-specific functions (deprecated)
- * =============================================================================
- */
+// /* =============================================================================
+//  * LOW-LEVEL RSA API - Algorithm-specific functions (deprecated)
+//  * =============================================================================
+//  */
 
 /**
  * Sign using low-level RSA_sign API (deprecated, RSA-only)
@@ -375,17 +375,13 @@ cleanup:
 int sign_using_rsa_sign(const unsigned char *message, size_t message_len,
                        unsigned char **signature, size_t *signature_len,
                        RSA *rsa_key, int hash_nid, const EVP_MD *md) {
-    unsigned char digest[EVP_MAX_MD_SIZE];
-    unsigned int digest_len;
     int ret = 0;
     
-    if (!create_digest(message, message_len, md, digest, &digest_len)) return 0;
-    
     *signature_len = RSA_size(rsa_key);
     *signature = OPENSSL_malloc(*signature_len);
     if (!*signature) return 0;
-    
-    if (RSA_sign(hash_nid, digest, digest_len, *signature, 
+
+    if (RSA_sign(hash_nid, message, message_len, *signature,
                  (unsigned int*)signature_len, rsa_key) == 1) {
         ret = 1;
     } else {
@@ -403,19 +399,15 @@ int sign_using_rsa_sign(const unsigned char *message, size_t message_len,
 int verify_using_rsa_verify(const unsigned char *message, size_t message_len,
                            const unsigned char *signature, size_t signature_len,
                            RSA *rsa_key, int hash_nid, const EVP_MD *md) {
-    unsigned char digest[EVP_MAX_MD_SIZE];
-    unsigned int digest_len;
-    
-    if (!create_digest(message, message_len, md, digest, &digest_len)) return 0;
-    
-    return RSA_verify(hash_nid, digest, digest_len, signature, 
+
+    return RSA_verify(hash_nid, message, message_len, signature,
                      (unsigned int)signature_len, rsa_key);
 }
 
-/* =============================================================================
- * LOW-LEVEL DSA API - Algorithm-specific functions (deprecated)
- * =============================================================================
- */
+// /* =============================================================================
+//  * LOW-LEVEL DSA API - Algorithm-specific functions (deprecated)
+//  * =============================================================================
+//  */
 
 /**
  * Sign using low-level DSA_do_sign API (deprecated, DSA-only)