Adding block mode models to openssl.

Author: bdrodes

cpp/ql/lib/experimental/Quantum/OpenSSL/EVPCipherAlgorithmSource.qll

@@ -4,12 +4,12 @@ import EVPCipherConsumers
 import OpenSSLAlgorithmGetter
 
 /**
- * Given a literal `e`, converts this to a cipher family type.
- * The literal must be a known literal representing a cipher algorithm.
- * If the literal does not represent any known cipher algorithm,
- * this predicate will not hold (i.e., it will not bind an unknown to an unknown cipher type)
+ * Given a `KnownOpenSSLAlgorithmConstant`, converts this to a cipher family type.
+ * Does not bind if there is know mapping (no mapping to 'unknown' or 'other').
  */
-predicate knownOpenSSLConstantToCipherFamilyType(KnownOpenSSLAlgorithmConstant e, Crypto::TCipherType type) {
+predicate knownOpenSSLConstantToCipherFamilyType(
+  KnownOpenSSLAlgorithmConstant e, Crypto::TCipherType type
+) {
   exists(string name | e.getAlgType().toLowerCase().matches("%encryption") |
     name = e.getNormalizedName() and
     (
@@ -90,16 +90,92 @@ class KnownOpenSSLCipherConstantAlgorithmInstance extends Crypto::CipherAlgorith
   }
 
   override Crypto::ModeOfOperationAlgorithmInstance getModeOfOperationAlgorithm() {
-    none() // TODO: provider defaults
+    // if there is a block mode associated with the same element, then that's the block mode
+    // note, if none are associated, we may need to parse if the cipher is a block cipher
+    // to determine if this is an unknown vs not relevant.
+    result = this
   }
 
   override Crypto::PaddingAlgorithmInstance getPaddingAlgorithm() { none() }
 
   override string getRawAlgorithmName() { result = this.(Literal).getValue().toString() }
 
-  override Crypto::TCipherType getCipherFamily() { 
-    knownOpenSSLConstantToCipherFamilyType(this, result) 
+  override Crypto::TCipherType getCipherFamily() {
+    knownOpenSSLConstantToCipherFamilyType(this, result)
     or
     not knownOpenSSLConstantToCipherFamilyType(this, _) and result = Crypto::OtherCipherType()
   }
-}
+}
+
+/**
+ * Given a `KnownOpenSSLAlgorithmConstant`, converts this to a cipher family type.
+ * Does not bind if there is know mapping (no mapping to 'unknown' or 'other').
+ */
+predicate knownOpenSSLConstantToBlockModeFamilyType(
+  KnownOpenSSLAlgorithmConstant e, Crypto::TBlockCipherModeOperationType type
+) {
+  exists(string name | e.getAlgType().toLowerCase().matches("block_mode") |
+    name = e.getNormalizedName() and
+    (
+      name.matches("CBC") and type instanceof Crypto::CBC
+      or
+      name.matches("CFB%") and type instanceof Crypto::CFB
+      or
+      name.matches("CTR") and type instanceof Crypto::CTR
+      or
+      name.matches("GCM") and type instanceof Crypto::GCM
+      or
+      name.matches("OFB") and type instanceof Crypto::OFB
+      or
+      name.matches("XTS") and type instanceof Crypto::XTS
+      or
+      name.matches("CCM") and type instanceof Crypto::CCM
+      or
+      name.matches("GCM") and type instanceof Crypto::GCM
+      or
+      name.matches("CCM") and type instanceof Crypto::CCM
+      or
+      name.matches("ECB") and type instanceof Crypto::ECB
+    )
+  )
+}
+
+class KnownOpenSSLBlockModeConstantAlgorithmInstance extends Crypto::ModeOfOperationAlgorithmInstance instanceof KnownOpenSSLAlgorithmConstant
+{
+  OpenSSLAlgorithmGetterCall getterCall;
+
+  KnownOpenSSLBlockModeConstantAlgorithmInstance() {
+    // Not just any known value, but specifically a known cipher operation
+    this.(KnownOpenSSLAlgorithmConstant).getAlgType().toLowerCase().matches("block_mode") and
+    (
+      // Two possibilities:
+      // 1) The source is a literal and flows to a getter, then we know we have an instance
+      // 2) The source is a KnownOpenSSLAlgorithm is call, and we know we have an instance immediately from that
+      // Possibility 1:
+      this instanceof Literal and
+      exists(DataFlow::Node src, DataFlow::Node sink |
+        // Sink is an argument to a CipherGetterCall
+        sink = getterCall.(OpenSSLAlgorithmGetterCall).getValueArgNode() and
+        // Source is `this`
+        src.asExpr() = this and
+        // This traces to a getter
+        KnownOpenSSLAlgorithmToAlgorithmGetterFlow::flow(src, sink)
+      )
+      or
+      // Possibility 2:
+      this instanceof DirectGetterCall and getterCall = this
+    )
+  }
+
+  override Crypto::TBlockCipherModeOperationType getModeType() {
+    knownOpenSSLConstantToBlockModeFamilyType(this, result)
+    or
+    not knownOpenSSLConstantToBlockModeFamilyType(this, _) and result = Crypto::OtherMode()
+  }
+
+  // NOTE: I'm not going to attempt to parse out the mode specific part, so returning
+  // the same as the raw name for now.
+  override string getRawModeAlgorithmName() { result = this.(Literal).getValue().toString() }
+
+  override string getRawAlgorithmName() { result = this.getRawModeAlgorithmName() }
+}