[dev.boringcrypto] crypto/tls/fipsonly: new package to force FIPS-allowed TLS settings

Change-Id: I3268cab2de8aed9e2424e9c3bc7667083bc5e1ce
Reviewed-on: https://go-review.googlesource.com/65250
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>

fipsonly/fipsonly.go

@@ -0,0 +1,27 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package fipsonly restricts all TLS configuration to FIPS-approved settings.
+//
+// The effect is triggered by importing the package anywhere in a program, as in:
+//
+//	import _ "crypto/tls/fipsonly"
+//
+// This package only exists in the dev.boringcrypto branch of Go.
+package fipsonly
+
+// This functionality is provided as a side effect of an import to make
+// it trivial to add to an existing program. It requires only a single line
+// added to an existing source file, or it can be done by adding a whole
+// new source file and not modifying any existing source files.
+
+import (
+	"crypto/internal/boring/fipstls"
+	"crypto/internal/boring/sig"
+)
+
+func init() {
+	fipstls.Force()
+	sig.FIPSOnly()
+}

fipsonly/fipsonly_test.go

@@ -0,0 +1,16 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fipsonly
+
+import (
+	"crypto/internal/boring/fipstls"
+	"testing"
+)
+
+func Test(t *testing.T) {
+	if !fipstls.Required() {
+		t.Fatal("fipstls.Required() = false, must be true")
+	}
+}