certificates/cas/softcas/softcas.go
2020-11-03 12:44:54 -08:00

218 lines
6.5 KiB
Go

package softcas
import (
"context"
"crypto"
"crypto/x509"
"time"
"github.com/pkg/errors"
"github.com/smallstep/certificates/cas/apiv1"
"github.com/smallstep/certificates/kms"
kmsapi "github.com/smallstep/certificates/kms/apiv1"
"go.step.sm/crypto/x509util"
)
func init() {
apiv1.Register(apiv1.SoftCAS, func(ctx context.Context, opts apiv1.Options) (apiv1.CertificateAuthorityService, error) {
return New(ctx, opts)
})
}
var now = func() time.Time {
return time.Now()
}
// SoftCAS implements a Certificate Authority Service using Golang or KMS
// crypto. This is the default CAS used in step-ca.
type SoftCAS struct {
Issuer *x509.Certificate
Signer crypto.Signer
KeyManager kms.KeyManager
}
// New creates a new CertificateAuthorityService implementation using Golang or KMS
// crypto.
func New(ctx context.Context, opts apiv1.Options) (*SoftCAS, error) {
if !opts.IsCreator {
switch {
case opts.Issuer == nil:
return nil, errors.New("softCAS 'issuer' cannot be nil")
case opts.Signer == nil:
return nil, errors.New("softCAS 'signer' cannot be nil")
}
}
return &SoftCAS{
Issuer: opts.Issuer,
Signer: opts.Signer,
KeyManager: opts.KeyManager,
}, nil
}
// CreateCertificate signs a new certificate using Golang or KMS crypto.
func (c *SoftCAS) CreateCertificate(req *apiv1.CreateCertificateRequest) (*apiv1.CreateCertificateResponse, error) {
switch {
case req.Template == nil:
return nil, errors.New("createCertificateRequest `template` cannot be nil")
case req.Lifetime == 0:
return nil, errors.New("createCertificateRequest `lifetime` cannot be 0")
}
t := now()
// Provisioners can also set specific values.
if req.Template.NotBefore.IsZero() {
req.Template.NotBefore = t.Add(-1 * req.Backdate)
}
if req.Template.NotAfter.IsZero() {
req.Template.NotAfter = t.Add(req.Lifetime)
}
req.Template.Issuer = c.Issuer.Subject
cert, err := x509util.CreateCertificate(req.Template, c.Issuer, req.Template.PublicKey, c.Signer)
if err != nil {
return nil, err
}
return &apiv1.CreateCertificateResponse{
Certificate: cert,
CertificateChain: []*x509.Certificate{
c.Issuer,
},
}, nil
}
// RenewCertificate signs the given certificate template using Golang or KMS crypto.
func (c *SoftCAS) RenewCertificate(req *apiv1.RenewCertificateRequest) (*apiv1.RenewCertificateResponse, error) {
switch {
case req.Template == nil:
return nil, errors.New("createCertificateRequest `template` cannot be nil")
case req.Lifetime == 0:
return nil, errors.New("createCertificateRequest `lifetime` cannot be 0")
}
t := now()
req.Template.NotBefore = t.Add(-1 * req.Backdate)
req.Template.NotAfter = t.Add(req.Lifetime)
req.Template.Issuer = c.Issuer.Subject
cert, err := x509util.CreateCertificate(req.Template, c.Issuer, req.Template.PublicKey, c.Signer)
if err != nil {
return nil, err
}
return &apiv1.RenewCertificateResponse{
Certificate: cert,
CertificateChain: []*x509.Certificate{
c.Issuer,
},
}, nil
}
// RevokeCertificate revokes the given certificate in step-ca. In SoftCAS this
// operation is a no-op as the actual revoke will happen when we store the entry
// in the db.
func (c *SoftCAS) RevokeCertificate(req *apiv1.RevokeCertificateRequest) (*apiv1.RevokeCertificateResponse, error) {
return &apiv1.RevokeCertificateResponse{
Certificate: req.Certificate,
CertificateChain: []*x509.Certificate{
c.Issuer,
},
}, nil
}
// CreateCertificateAuthority creates a root or an intermediate certificate.
func (c *SoftCAS) CreateCertificateAuthority(req *apiv1.CreateCertificateAuthorityRequest) (*apiv1.CreateCertificateAuthorityResponse, error) {
switch {
case req.Template == nil:
return nil, errors.New("createCertificateAuthorityRequest `template` cannot be nil")
case req.Lifetime == 0:
return nil, errors.New("createCertificateAuthorityRequest `lifetime` cannot be 0")
case req.Type == apiv1.IntermediateCA && req.Parent == nil:
return nil, errors.New("createCertificateAuthorityRequest `parent` cannot be nil")
case req.Type == apiv1.IntermediateCA && req.Parent.Certificate == nil:
return nil, errors.New("createCertificateAuthorityRequest `parent.template` cannot be nil")
case req.Type == apiv1.IntermediateCA && req.Parent.Signer == nil:
return nil, errors.New("createCertificateAuthorityRequest `parent.signer` cannot be nil")
}
key, err := c.createKey(req.CreateKey)
if err != nil {
return nil, err
}
signer, err := c.createSigner(&key.CreateSignerRequest)
if err != nil {
return nil, err
}
t := now()
if req.Template.NotBefore.IsZero() {
req.Template.NotBefore = t.Add(-1 * req.Backdate)
}
if req.Template.NotAfter.IsZero() {
req.Template.NotAfter = t.Add(req.Lifetime)
}
var cert *x509.Certificate
switch req.Type {
case apiv1.RootCA:
cert, err = x509util.CreateCertificate(req.Template, req.Template, signer.Public(), signer)
if err != nil {
return nil, err
}
case apiv1.IntermediateCA:
cert, err = x509util.CreateCertificate(req.Template, req.Parent.Certificate, signer.Public(), req.Parent.Signer)
if err != nil {
return nil, err
}
default:
return nil, errors.Errorf("createCertificateAuthorityRequest `type=%d' is invalid or not supported", req.Type)
}
// Add the parent
var chain []*x509.Certificate
if req.Parent != nil {
chain = append(chain, req.Parent.Certificate)
chain = append(chain, req.Parent.CertificateChain...)
}
return &apiv1.CreateCertificateAuthorityResponse{
Name: cert.Subject.CommonName,
Certificate: cert,
CertificateChain: chain,
PublicKey: key.PublicKey,
PrivateKey: key.PrivateKey,
Signer: signer,
}, nil
}
// initializeKeyManager initiazes the default key manager if was not given.
func (c *SoftCAS) initializeKeyManager() (err error) {
if c.KeyManager == nil {
c.KeyManager, err = kms.New(context.Background(), kmsapi.Options{
Type: string(kmsapi.DefaultKMS),
})
}
return
}
// createKey uses the configured kms to create a key.
func (c *SoftCAS) createKey(req *kmsapi.CreateKeyRequest) (*kmsapi.CreateKeyResponse, error) {
if err := c.initializeKeyManager(); err != nil {
return nil, err
}
if req == nil {
req = &kmsapi.CreateKeyRequest{
SignatureAlgorithm: kmsapi.ECDSAWithSHA256,
}
}
return c.KeyManager.CreateKey(req)
}
// createSigner uses the configured kms to create a singer
func (c *SoftCAS) createSigner(req *kmsapi.CreateSignerRequest) (crypto.Signer, error) {
if err := c.initializeKeyManager(); err != nil {
return nil, err
}
return c.KeyManager.CreateSigner(req)
}