Add taint-tracking for mime package.

Author: gagliardetto

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

@@ -12,6 +12,7 @@ import semmle.go.frameworks.stdlib.CompressFlate
 import semmle.go.frameworks.stdlib.CompressGzip
 import semmle.go.frameworks.stdlib.CompressLzw
 import semmle.go.frameworks.stdlib.CompressZlib
+import semmle.go.frameworks.stdlib.Mime
 import semmle.go.frameworks.stdlib.Path
 import semmle.go.frameworks.stdlib.PathFilepath
 

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

@@ -0,0 +1,50 @@
+/**
+ * Provides classes modeling security-relevant aspects of the `mime` package.
+ */
+
+import go
+
+/** Provides models of commonly used functions in the `mime` package. */
+module Mime {
+  private class FunctionModels extends TaintTracking::FunctionModel {
+    FunctionInput inp;
+    FunctionOutput outp;
+
+    FunctionModels() {
+      // signature: func FormatMediaType(t string, param map[string]string) string
+      hasQualifiedName("mime", "FormatMediaType") and
+      (inp.isParameter(_) and outp.isResult())
+      or
+      // signature: func ParseMediaType(v string) (mediatype string, params map[string]string, err error)
+      hasQualifiedName("mime", "ParseMediaType") and
+      (inp.isParameter(0) and outp.isResult([0, 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 (*WordDecoder).Decode(word string) (string, error)
+      this.hasQualifiedName("mime", "WordDecoder", "Decode") and
+      (inp.isParameter(0) and outp.isResult(0))
+      or
+      // signature: func (*WordDecoder).DecodeHeader(header string) (string, error)
+      this.hasQualifiedName("mime", "WordDecoder", "DecodeHeader") and
+      (inp.isParameter(0) and outp.isResult(0))
+      or
+      // signature: func (WordEncoder).Encode(charset string, s string) string
+      this.hasQualifiedName("mime", "WordEncoder", "Encode") and
+      (inp.isParameter(1) and outp.isResult())
+    }
+
+    override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
+      input = inp and output = outp
+    }
+  }
+}