From 00fd41a3d0b4726fe2bef8f97bb1d3d352b0205a Mon Sep 17 00:00:00 2001
From: Mariano Cano <mariano@smallstep.com>
Date: Mon, 13 Jul 2020 14:36:59 -0700
Subject: [PATCH] Add template support to K8sSA provisioners.

---
 authority/provisioner/k8sSA.go | 18 ++++++++++++++----
 x509util/extensions.go         |  7 +++++++
 x509util/options.go            |  2 --
 x509util/templates.go          |  4 ++++
 4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/authority/provisioner/k8sSA.go b/authority/provisioner/k8sSA.go
index b63ce979..143e28f3 100644
--- a/authority/provisioner/k8sSA.go
+++ b/authority/provisioner/k8sSA.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/pkg/errors"
 	"github.com/smallstep/certificates/errs"
+	"github.com/smallstep/certificates/x509util"
 	"github.com/smallstep/cli/crypto/pemutil"
 	"github.com/smallstep/cli/jose"
 	"golang.org/x/crypto/ed25519"
@@ -40,10 +41,11 @@ type k8sSAPayload struct {
 // entity trusted to make signature requests.
 type K8sSA struct {
 	*base
-	Type      string  `json:"type"`
-	Name      string  `json:"name"`
-	Claims    *Claims `json:"claims,omitempty"`
-	PubKeys   []byte  `json:"publicKeys,omitempty"`
+	Type      string              `json:"type"`
+	Name      string              `json:"name"`
+	PubKeys   []byte              `json:"publicKeys,omitempty"`
+	Claims    *Claims             `json:"claims,omitempty"`
+	Options   *ProvisionerOptions `json:"options,omitempty"`
 	claimer   *Claimer
 	audiences Audiences
 	//kauthn    kauthn.AuthenticationV1Interface
@@ -208,7 +210,15 @@ func (p *K8sSA) AuthorizeSign(ctx context.Context, token string) ([]SignOption,
 		return nil, errs.Wrap(http.StatusInternalServerError, err, "k8ssa.AuthorizeSign")
 	}
 
+	// Certificate templates: on K8sSA the default template is the certificate
+	// request.
+	templateOptions, err := CustomTemplateOptions(p.Options, x509util.NewTemplateData(), x509util.CertificateRequestTemplate)
+	if err != nil {
+		return nil, errs.Wrap(http.StatusInternalServerError, err, "k8ssa.AuthorizeSign")
+	}
+
 	return []SignOption{
+		templateOptions,
 		// modifiers / withOptions
 		newProvisionerExtensionOption(TypeK8sSA, p.Name, ""),
 		profileDefaultDuration(p.claimer.DefaultTLSCertDuration()),
diff --git a/x509util/extensions.go b/x509util/extensions.go
index 8c7eecf4..ffecd2dd 100644
--- a/x509util/extensions.go
+++ b/x509util/extensions.go
@@ -4,6 +4,7 @@ import (
 	"crypto/x509"
 	"crypto/x509/pkix"
 	"encoding/asn1"
+	"encoding/json"
 	"fmt"
 	"net"
 	"net/url"
@@ -76,6 +77,12 @@ func (e Extension) Set(c *x509.Certificate) {
 // object identifier or OID.
 type ObjectIdentifier asn1.ObjectIdentifier
 
+// MarshalJSON implements the json.Marshaler interface and returns the string
+// version of the asn1.ObjectIdentifier.
+func (o ObjectIdentifier) MarshalJSON() ([]byte, error) {
+	return json.Marshal(asn1.ObjectIdentifier(o).String())
+}
+
 // UnmarshalJSON implements the json.Unmarshaler interface and coverts a strings
 // like "2.5.29.17" into an ASN1 object identifier.
 func (o *ObjectIdentifier) UnmarshalJSON(data []byte) error {
diff --git a/x509util/options.go b/x509util/options.go
index cd261f2b..9a061bed 100644
--- a/x509util/options.go
+++ b/x509util/options.go
@@ -3,7 +3,6 @@ package x509util
 import (
 	"bytes"
 	"crypto/x509"
-	"fmt"
 	"io/ioutil"
 	"text/template"
 
@@ -43,7 +42,6 @@ func WithTemplate(text string, data TemplateData) Option {
 		if err := tmpl.Execute(buf, data); err != nil {
 			return errors.Wrapf(err, "error executing template")
 		}
-		fmt.Println(buf.String())
 		o.CertBuffer = buf
 		return nil
 	}
diff --git a/x509util/templates.go b/x509util/templates.go
index bcbb7059..c7e8211e 100644
--- a/x509util/templates.go
+++ b/x509util/templates.go
@@ -113,3 +113,7 @@ const DefaultRootTemplate = `{
 		"maxPathLen": 1
 	}
 }`
+
+// CertificateRequestTemplate is a template that will sign the given certificate
+// request.
+const CertificateRequestTemplate = `{{ toJson .CR }}`