Add taint-tracking for encoding/asn1

Author: gagliardetto

ql/src/semmle/go/frameworks/Stdlib.qll

@@ -17,6 +17,7 @@ import semmle.go.frameworks.stdlib.MimeMultipart
 import semmle.go.frameworks.stdlib.MimeQuotedprintable
 import semmle.go.frameworks.stdlib.Encoding
 import semmle.go.frameworks.stdlib.EncodingAscii85
+import semmle.go.frameworks.stdlib.EncodingAsn1
 import semmle.go.frameworks.stdlib.Path
 import semmle.go.frameworks.stdlib.PathFilepath
 import semmle.go.frameworks.stdlib.Reflect

ql/src/semmle/go/frameworks/stdlib/EncodingAsn1.qll

@@ -0,0 +1,41 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `encoding/asn1` package.
+ */
+
+import go
+
+/** Provides models of commonly used functions in the `encoding/asn1` package. */
+module EncodingAsn1 {
+  private class FunctionModels extends TaintTracking::FunctionModel {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    FunctionModels() {
+      // signature: func Marshal(val interface{}) ([]byte, error)
+      hasQualifiedName("encoding/asn1", "Marshal") and
+      (inp.isParameter(0) and outp.isResult(0))
+      or
+      // signature: func MarshalWithParams(val interface{}, params string) ([]byte, error)
+      hasQualifiedName("encoding/asn1", "MarshalWithParams") and
+      (inp.isParameter(_) and outp.isResult(0))
+      or
+      // signature: func Unmarshal(b []byte, val interface{}) (rest []byte, err error)
+      hasQualifiedName("encoding/asn1", "Unmarshal") and
+      (
+        inp.isParameter(0) and
+        (outp.isParameter(1) or outp.isResult(0))
+      )
+      or
+      // signature: func UnmarshalWithParams(b []byte, val interface{}, params string) (rest []byte, err error)
+      hasQualifiedName("encoding/asn1", "UnmarshalWithParams") and
+      (
+        inp.isParameter([0, 2]) and
+        (outp.isParameter(1) or outp.isResult(0))
+      )
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+}