Initial commit for: wrong use of package unsafe

ql/src/experimental/Unsafe/Unsafe.ql

@@ -0,0 +1,153 @@
+/**
+ * @kind path-problem
+ */
+
+import go
+import DataFlow::PathGraph
+
+Type getBaseType(Type typ) {
+  result =
+    getBaseType*(typ.getUnderlyingType*().(PointerType).getBaseType*().getUnderlyingType*())
+        .getUnderlyingType*()
+  or
+  result = typ
+}
+
+Type getFinalType(Type typ) {
+  result = getFinalType*(typ.getUnderlyingType*())
+  or
+  result = typ
+}
+
+class ConversionToUnsafePointer extends ConversionExpr {
+  ConversionToUnsafePointer() { getBaseType(getType()) instanceof UnsafePointerType }
+}
+
+class ShortToLongerArrayConf extends TaintTracking::Configuration {
+  ShortToLongerArrayConf() { this = "ShortToLongerArrayConf" }
+
+  predicate isSource(DataFlow::Node source, ConversionToUnsafePointer conv) {
+    source.asExpr() = conv
+  }
+
+  predicate isSink(DataFlow::Node sink, ConversionExpr ca) {
+    ca.getOperand().getType() instanceof UnsafePointerType and
+    sink.asExpr() = ca
+  }
+
+  override predicate isSource(DataFlow::Node source) { isSource(source, _) }
+
+  override predicate isSink(DataFlow::Node sink) { isSink(sink, _) }
+}
+
+predicate castShortArrayToLongerArray(
+  DataFlow::PathNode source, DataFlow::PathNode sink, string message
+) {
+  exists(
+    ShortToLongerArrayConf cfg, ConversionExpr castBig, ConversionToUnsafePointer castLittle,
+    ArrayType arrTo, ArrayType arrFrom
+  |
+    cfg.hasFlowPath(source, sink) and
+    cfg.isSource(source.getNode(), castLittle) and
+    cfg.isSink(sink.getNode(), castBig) and
+    //castBig.getTypeExpr().getAChildExpr*().getType() instanceof ArrayType and
+    arrTo = getBaseType(castBig.getTypeExpr().getType()) and
+    arrFrom = getBaseType(castLittle.getOperand().getType()) and
+    arrTo.getLength() > 0 and //TODO
+    arrTo.getLength() > arrFrom.getLength() and
+    message =
+      "Dangerous array type casting to [" + arrTo.getLength() + "]" + arrTo.getElementType() +
+        " from [" + arrFrom.getLength() + "]" + arrFrom.getElementType() //and
+    //arrTo.getElementType() instanceof Uint8Type and
+    //arrFrom.getElementType() instanceof Uint8Type
+  )
+}
+
+predicate castTypeToArray(DataFlow::PathNode source, DataFlow::PathNode sink, string message) {
+  exists(
+    ShortToLongerArrayConf cfg, ConversionExpr castBig, ConversionToUnsafePointer castLittle,
+    ArrayType arrTo, Type typeFrom
+  |
+    cfg.hasFlowPath(source, sink) and
+    cfg.isSource(source.getNode(), castLittle) and
+    cfg.isSink(sink.getNode(), castBig) and
+    //castBig.getTypeExpr().getAChildExpr*().getType() instanceof ArrayType and
+    arrTo = getBaseType(castBig.getTypeExpr().getType()) and
+    not (typeFrom instanceof ArrayType or typeFrom.getUnderlyingType() instanceof ArrayType) and
+    not typeFrom instanceof PointerType and
+    typeFrom = getBaseType(castLittle.getOperand().getType()) and
+    //typeFrom = getBaseType(typeFrom) and
+    message =
+      "Dangerous type up-casting to [" + arrTo.getLength() + "]" + arrTo.getElementType() + " from "
+        + typeFrom //and
+    //arrTo.getElementType() instanceof Uint8Type and
+    //arrFrom.getElementType() instanceof Uint8Type
+  )
+}
+
+class NumberCastingFlowConf extends TaintTracking::Configuration {
+  NumberCastingFlowConf() { this = "NumberCastingFlowConf" }
+
+  predicate isSource(DataFlow::Node source, ConversionToUnsafePointer conv) {
+    source.asExpr() = conv
+  }
+
+  predicate isSink(DataFlow::Node sink, ConversionExpr ca) {
+    ca.getOperand().getType() instanceof UnsafePointerType and
+    sink.asExpr() = ca
+  }
+
+  override predicate isSource(DataFlow::Node source) { isSource(source, _) }
+
+  override predicate isSink(DataFlow::Node sink) { isSink(sink, _) }
+}
+
+predicate castDifferentBitSizeNumbers(
+  DataFlow::PathNode source, DataFlow::PathNode sink, string message
+) {
+  exists(
+    NumberCastingFlowConf cfg, ConversionExpr castBig, ConversionToUnsafePointer castLittle,
+    CustomNumericType numTo, CustomNumericType numFrom
+  |
+    cfg.hasFlowPath(source, sink) and
+    cfg.isSource(source.getNode(), castLittle) and
+    cfg.isSink(sink.getNode(), castBig) and
+    numTo = getBaseType(castBig.getTypeExpr().getType()) and
+    (
+      numFrom = getBaseType(castLittle.getOperand().getType()) or
+      numFrom =
+        getBaseType(getBaseType(castLittle.getOperand().getType())
+              .(StructType)
+              .getField(_)
+              .getType())
+    ) and
+    // TODO: also consider cast from uint to int?
+    numTo.getSize() != numFrom.getSize() and
+    message = "Dangerous numeric type casting to " + numTo.getName() + " from " + numFrom.getName()
+  )
+}
+
+class CustomNumericType extends NumericType {
+  CustomNumericType() { this instanceof NumericType }
+
+  override int getSize() {
+    (
+      // If the numeric types have arch-specific
+      // bit sizes, then set the size to 0 to distinguish
+      // it from others.
+      this instanceof UintType
+      or
+      this instanceof IntType
+    ) and
+    result = 0
+    or
+    result = this.(NumericType).getSize()
+  }
+}
+
+from DataFlow::PathNode source, DataFlow::PathNode sink, string message
+where
+  castShortArrayToLongerArray(source, sink, message) or
+  castTypeToArray(source, sink, message) or
+  castDifferentBitSizeNumbers(source, sink, message)
+select sink.getNode(), source, sink, "$@.", source.getNode(), message