Add taint-tracking for encoding/ascii85

Author: gagliardetto

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

@@ -16,6 +16,7 @@ import semmle.go.frameworks.stdlib.Mime
 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.Path
 import semmle.go.frameworks.stdlib.PathFilepath
 import semmle.go.frameworks.stdlib.Reflect

ql/src/semmle/go/frameworks/stdlib/EncodingAscii85.qll

@@ -0,0 +1,35 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `encoding/ascii85` package.
+ */
+
+import go
+
+/** Provides models of commonly used functions in the `encoding/ascii85` package. */
+module EncodingAscii85 {
+  private class FunctionModels extends TaintTracking::FunctionModel {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    FunctionModels() {
+      // signature: func Decode(dst []byte, src []byte, flush bool) (ndst int, nsrc int, err error)
+      hasQualifiedName("encoding/ascii85", "Decode") and
+      (inp.isParameter(1) and outp.isParameter(0))
+      or
+      // signature: func Encode(dst []byte, src []byte) int
+      hasQualifiedName("encoding/ascii85", "Encode") and
+      (inp.isParameter(1) and outp.isParameter(0))
+      or
+      // signature: func NewDecoder(r io.Reader) io.Reader
+      hasQualifiedName("encoding/ascii85", "NewDecoder") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func NewEncoder(w io.Writer) io.WriteCloser
+      hasQualifiedName("encoding/ascii85", "NewEncoder") and
+      (inp.isResult() and outp.isParameter(0))
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+}