Add taint-tracking for encoding/json

Author: gagliardetto

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

@@ -24,6 +24,7 @@ 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.EncodingJson
 import semmle.go.frameworks.stdlib.Path
 import semmle.go.frameworks.stdlib.PathFilepath
 import semmle.go.frameworks.stdlib.Reflect

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

@@ -0,0 +1,98 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `encoding/json` package.
+ */
+
+import go
+
+/** Provides models of commonly used functions in the `encoding/json` package. */
+module EncodingJson {
+  private class FunctionModels extends TaintTracking::FunctionModel {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    FunctionModels() {
+      // signature: func Compact(dst *bytes.Buffer, src []byte) error
+      hasQualifiedName("encoding/json", "Compact") and
+      (inp.isParameter(1) and outp.isParameter(0))
+      or
+      // signature: func HTMLEscape(dst *bytes.Buffer, src []byte)
+      hasQualifiedName("encoding/json", "HTMLEscape") and
+      (inp.isParameter(1) and outp.isParameter(0))
+      or
+      // signature: func Indent(dst *bytes.Buffer, src []byte, prefix string, indent string) error
+      hasQualifiedName("encoding/json", "Indent") and
+      (inp.isParameter([1, 2, 3]) and outp.isParameter(0))
+      or
+      // signature: func Marshal(v interface{}) ([]byte, error)
+      hasQualifiedName("encoding/json", "Marshal") and
+      (inp.isParameter(0) and outp.isResult(0))
+      or
+      // signature: func MarshalIndent(v interface{}, prefix string, indent string) ([]byte, error)
+      hasQualifiedName("encoding/json", "MarshalIndent") and
+      (inp.isParameter(_) and outp.isResult(0))
+      or
+      // signature: func NewDecoder(r io.Reader) *Decoder
+      hasQualifiedName("encoding/json", "NewDecoder") and
+      (inp.isParameter(0) and outp.isResult())
+      or
+      // signature: func NewEncoder(w io.Writer) *Encoder
+      hasQualifiedName("encoding/json", "NewEncoder") and
+      (inp.isResult() and outp.isParameter(0))
+      or
+      // signature: func Unmarshal(data []byte, v interface{}) error
+      hasQualifiedName("encoding/json", "Unmarshal") and
+      (inp.isParameter(0) and outp.isParameter(1))
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+
+  private class MethodModels extends TaintTracking::FunctionModel, Method {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    MethodModels() {
+      // signature: func (*Decoder).Buffered() io.Reader
+      this.hasQualifiedName("encoding/json", "Decoder", "Buffered") and
+      (inp.isReceiver() and outp.isResult())
+      or
+      // signature: func (*Decoder).Decode(v interface{}) error
+      this.hasQualifiedName("encoding/json", "Decoder", "Decode") and
+      (inp.isReceiver() and outp.isParameter(0))
+      or
+      // signature: func (*Decoder).Token() (Token, error)
+      this.hasQualifiedName("encoding/json", "Decoder", "Token") and
+      (inp.isReceiver() and outp.isResult(0))
+      or
+      // signature: func (*Encoder).Encode(v interface{}) error
+      this.hasQualifiedName("encoding/json", "Encoder", "Encode") and
+      (inp.isParameter(0) and outp.isReceiver())
+      or
+      // signature: func (*Encoder).SetIndent(prefix string, indent string)
+      this.hasQualifiedName("encoding/json", "Encoder", "SetIndent") and
+      (inp.isParameter(_) and outp.isReceiver())
+      or
+      // signature: func (RawMessage).MarshalJSON() ([]byte, error)
+      this.hasQualifiedName("encoding/json", "RawMessage", "MarshalJSON") and
+      (inp.isReceiver() and outp.isResult(0))
+      or
+      // signature: func (*RawMessage).UnmarshalJSON(data []byte) error
+      this.hasQualifiedName("encoding/json", "RawMessage", "UnmarshalJSON") and
+      (inp.isParameter(0) and outp.isReceiver())
+      or
+      // signature: func (Marshaler).MarshalJSON() ([]byte, error)
+      this.implements("encoding/json", "Marshaler", "MarshalJSON") and
+      (inp.isReceiver() and outp.isResult(0))
+      or
+      // signature: func (Unmarshaler).UnmarshalJSON([]byte) error
+      this.implements("encoding/json", "Unmarshaler", "UnmarshalJSON") and
+      (inp.isParameter(0) and outp.isReceiver())
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+}