Add taint-tracking for encoding/hex

Author: gagliardetto

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

@@ -23,6 +23,7 @@ import semmle.go.frameworks.stdlib.EncodingBase64
 import semmle.go.frameworks.stdlib.EncodingBinary
 import semmle.go.frameworks.stdlib.EncodingCsv
 import semmle.go.frameworks.stdlib.EncodingGob
+import semmle.go.frameworks.stdlib.EncodingHex
 import semmle.go.frameworks.stdlib.Path
 import semmle.go.frameworks.stdlib.PathFilepath
 import semmle.go.frameworks.stdlib.Reflect

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

@@ -0,0 +1,51 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `encoding/hex` package.
+ */
+
+import go
+
+/** Provides models of commonly used functions in the `encoding/hex` package. */
+module EncodingHex {
+  private class FunctionModels extends TaintTracking::FunctionModel {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    FunctionModels() {
+      // signature: func Decode(dst []byte, src []byte) (int, error)
+      hasQualifiedName("encoding/hex", "Decode") and
+      (inp.isParameter(1) and outp.isParameter(0))
+      or
+      // signature: func DecodeString(s string) ([]byte, error)
+      hasQualifiedName("encoding/hex", "DecodeString") and
+      (inp.isParameter(0) and outp.isResult(0))
+      or
+      // signature: func Dump(data []byte) string
+      hasQualifiedName("encoding/hex", "Dump") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func Dumper(w io.Writer) io.WriteCloser
+      hasQualifiedName("encoding/hex", "Dumper") and
+      (inp.isResult() and outp.isParameter(0))
+      or
+      // signature: func Encode(dst []byte, src []byte) int
+      hasQualifiedName("encoding/hex", "Encode") and
+      (inp.isParameter(1) and outp.isParameter(0))
+      or
+      // signature: func EncodeToString(src []byte) string
+      hasQualifiedName("encoding/hex", "EncodeToString") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func NewDecoder(r io.Reader) io.Reader
+      hasQualifiedName("encoding/hex", "NewDecoder") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func NewEncoder(w io.Writer) io.Writer
+      hasQualifiedName("encoding/hex", "NewEncoder") and
+      (inp.isResult() and outp.isParameter(0))
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+}