Add taint-tracking for text/tabwriter package.

Author: gagliardetto

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

@@ -15,6 +15,7 @@ import semmle.go.frameworks.stdlib.CompressZlib
 import semmle.go.frameworks.stdlib.Path
 import semmle.go.frameworks.stdlib.PathFilepath
 import semmle.go.frameworks.stdlib.TextScanner
+import semmle.go.frameworks.stdlib.TextTabwriter
 
 /** A `String()` method. */
 class StringMethod extends TaintTracking::FunctionModel, Method {

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

@@ -0,0 +1,45 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `text/tabwriter` package.
+ */
+
+import go
+
+/** Provides models of commonly used functions in the `text/tabwriter` package. */
+module TextTabwriter {
+  private class FunctionModels extends TaintTracking::FunctionModel {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    FunctionModels() {
+      // signature: func NewWriter(output io.Writer, minwidth int, tabwidth int, padding int, padchar byte, flags uint) *Writer
+      hasQualifiedName("text/tabwriter", "NewWriter") and
+      (inp.isResult() and outp.isParameter(0))
+    }
+
+    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 (*Writer).Init(output io.Writer, minwidth int, tabwidth int, padding int, padchar byte, flags uint) *Writer
+      this.hasQualifiedName("text/tabwriter", "Writer", "Init") and
+      (
+        (inp.isReceiver() or inp.isResult()) and
+        outp.isParameter(0)
+      )
+      or
+      // signature: func (*Writer).Write(buf []byte) (n int, err error)
+      this.hasQualifiedName("text/tabwriter", "Writer", "Write") and
+      (inp.isParameter(0) and outp.isReceiver())
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+}