forked from TrueCloudLab/certificates
286 lines
8.7 KiB
Go
286 lines
8.7 KiB
Go
package softcas
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import (
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"context"
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"crypto"
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"crypto/rsa"
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"crypto/rand"
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"crypto/x509"
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"time"
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"github.com/pkg/errors"
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"go.step.sm/crypto/kms"
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kmsapi "go.step.sm/crypto/kms/apiv1"
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"go.step.sm/crypto/x509util"
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"github.com/smallstep/certificates/cas/apiv1"
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)
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func init() {
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apiv1.Register(apiv1.SoftCAS, func(ctx context.Context, opts apiv1.Options) (apiv1.CertificateAuthorityService, error) {
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return New(ctx, opts)
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})
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}
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var now = time.Now
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// SoftCAS implements a Certificate Authority Service using Golang or KMS
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// crypto. This is the default CAS used in step-ca.
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type SoftCAS struct {
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CertificateChain []*x509.Certificate
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Signer crypto.Signer
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CertificateSigner func() ([]*x509.Certificate, crypto.Signer, error)
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KeyManager kms.KeyManager
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}
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// New creates a new CertificateAuthorityService implementation using Golang or KMS
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// crypto.
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func New(ctx context.Context, opts apiv1.Options) (*SoftCAS, error) {
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if !opts.IsCreator {
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switch {
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case len(opts.CertificateChain) == 0 && opts.CertificateSigner == nil:
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return nil, errors.New("softCAS 'CertificateChain' cannot be nil")
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case opts.Signer == nil && opts.CertificateSigner == nil:
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return nil, errors.New("softCAS 'signer' cannot be nil")
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}
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}
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return &SoftCAS{
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CertificateChain: opts.CertificateChain,
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Signer: opts.Signer,
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CertificateSigner: opts.CertificateSigner,
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KeyManager: opts.KeyManager,
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}, nil
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}
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// CreateCertificate signs a new certificate using Golang or KMS crypto.
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func (c *SoftCAS) CreateCertificate(req *apiv1.CreateCertificateRequest) (*apiv1.CreateCertificateResponse, error) {
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switch {
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case req.Template == nil:
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return nil, errors.New("createCertificateRequest `template` cannot be nil")
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case req.Lifetime == 0:
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return nil, errors.New("createCertificateRequest `lifetime` cannot be 0")
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}
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t := now()
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// Provisioners can also set specific values.
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if req.Template.NotBefore.IsZero() {
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req.Template.NotBefore = t.Add(-1 * req.Backdate)
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}
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if req.Template.NotAfter.IsZero() {
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req.Template.NotAfter = t.Add(req.Lifetime)
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}
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chain, signer, err := c.getCertSigner()
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if err != nil {
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return nil, err
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}
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req.Template.Issuer = chain[0].Subject
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cert, err := createCertificate(req.Template, chain[0], req.Template.PublicKey, signer)
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if err != nil {
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return nil, err
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}
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return &apiv1.CreateCertificateResponse{
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Certificate: cert,
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CertificateChain: chain,
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}, nil
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}
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// RenewCertificate signs the given certificate template using Golang or KMS crypto.
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func (c *SoftCAS) RenewCertificate(req *apiv1.RenewCertificateRequest) (*apiv1.RenewCertificateResponse, error) {
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switch {
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case req.Template == nil:
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return nil, errors.New("createCertificateRequest `template` cannot be nil")
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case req.Lifetime == 0:
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return nil, errors.New("createCertificateRequest `lifetime` cannot be 0")
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}
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t := now()
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req.Template.NotBefore = t.Add(-1 * req.Backdate)
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req.Template.NotAfter = t.Add(req.Lifetime)
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chain, signer, err := c.getCertSigner()
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if err != nil {
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return nil, err
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}
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req.Template.Issuer = chain[0].Subject
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cert, err := createCertificate(req.Template, chain[0], req.Template.PublicKey, signer)
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if err != nil {
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return nil, err
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}
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return &apiv1.RenewCertificateResponse{
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Certificate: cert,
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CertificateChain: chain,
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}, nil
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}
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// RevokeCertificate revokes the given certificate in step-ca. In SoftCAS this
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// operation is a no-op as the actual revoke will happen when we store the entry
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// in the db.
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func (c *SoftCAS) RevokeCertificate(req *apiv1.RevokeCertificateRequest) (*apiv1.RevokeCertificateResponse, error) {
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chain, _, err := c.getCertSigner()
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if err != nil {
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return nil, err
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}
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return &apiv1.RevokeCertificateResponse{
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Certificate: req.Certificate,
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CertificateChain: chain,
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}, nil
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}
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// CreateCRL will create a new CRL based on the RevocationList passed to it
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func (c *SoftCAS) CreateCRL(req *apiv1.CreateCRLRequest) (*apiv1.CreateCRLResponse, error) {
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certChain, signer, err := c.getCertSigner()
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if err != nil {
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return nil, err
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}
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revocationListBytes, err := x509.CreateRevocationList(rand.Reader, req.RevocationList, certChain[0], signer)
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if err != nil {
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return nil, err
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}
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return &apiv1.CreateCRLResponse{CRL: revocationListBytes}, nil
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}
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// CreateCertificateAuthority creates a root or an intermediate certificate.
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func (c *SoftCAS) CreateCertificateAuthority(req *apiv1.CreateCertificateAuthorityRequest) (*apiv1.CreateCertificateAuthorityResponse, error) {
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switch {
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case req.Template == nil:
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return nil, errors.New("createCertificateAuthorityRequest `template` cannot be nil")
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case req.Lifetime == 0:
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return nil, errors.New("createCertificateAuthorityRequest `lifetime` cannot be 0")
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case req.Type == apiv1.IntermediateCA && req.Parent == nil:
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return nil, errors.New("createCertificateAuthorityRequest `parent` cannot be nil")
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case req.Type == apiv1.IntermediateCA && req.Parent.Certificate == nil:
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return nil, errors.New("createCertificateAuthorityRequest `parent.template` cannot be nil")
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case req.Type == apiv1.IntermediateCA && req.Parent.Signer == nil:
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return nil, errors.New("createCertificateAuthorityRequest `parent.signer` cannot be nil")
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}
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key, err := c.createKey(req.CreateKey)
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if err != nil {
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return nil, err
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}
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signer, err := c.createSigner(&key.CreateSignerRequest)
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if err != nil {
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return nil, err
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}
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t := now()
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if req.Template.NotBefore.IsZero() {
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req.Template.NotBefore = t.Add(-1 * req.Backdate)
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}
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if req.Template.NotAfter.IsZero() {
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req.Template.NotAfter = t.Add(req.Lifetime)
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}
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var cert *x509.Certificate
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switch req.Type {
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case apiv1.RootCA:
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cert, err = createCertificate(req.Template, req.Template, signer.Public(), signer)
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if err != nil {
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return nil, err
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}
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case apiv1.IntermediateCA:
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cert, err = createCertificate(req.Template, req.Parent.Certificate, signer.Public(), req.Parent.Signer)
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if err != nil {
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return nil, err
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}
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default:
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return nil, errors.Errorf("createCertificateAuthorityRequest `type=%d' is invalid or not supported", req.Type)
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}
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// Add the parent
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var chain []*x509.Certificate
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if req.Parent != nil {
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chain = append(chain, req.Parent.Certificate)
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chain = append(chain, req.Parent.CertificateChain...)
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}
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return &apiv1.CreateCertificateAuthorityResponse{
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Name: cert.Subject.CommonName,
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Certificate: cert,
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CertificateChain: chain,
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KeyName: key.Name,
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PublicKey: key.PublicKey,
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PrivateKey: key.PrivateKey,
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Signer: signer,
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}, nil
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}
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// initializeKeyManager initializes the default key manager if was not given.
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func (c *SoftCAS) initializeKeyManager() (err error) {
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if c.KeyManager == nil {
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c.KeyManager, err = kms.New(context.Background(), kmsapi.Options{
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Type: kmsapi.DefaultKMS,
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})
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}
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return
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}
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// getCertSigner returns the certificate chain and signer to use.
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func (c *SoftCAS) getCertSigner() ([]*x509.Certificate, crypto.Signer, error) {
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if c.CertificateSigner != nil {
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return c.CertificateSigner()
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}
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return c.CertificateChain, c.Signer, nil
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}
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// createKey uses the configured kms to create a key.
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func (c *SoftCAS) createKey(req *kmsapi.CreateKeyRequest) (*kmsapi.CreateKeyResponse, error) {
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if err := c.initializeKeyManager(); err != nil {
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return nil, err
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}
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if req == nil {
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req = &kmsapi.CreateKeyRequest{
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SignatureAlgorithm: kmsapi.ECDSAWithSHA256,
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}
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}
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return c.KeyManager.CreateKey(req)
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}
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// createSigner uses the configured kms to create a singer
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func (c *SoftCAS) createSigner(req *kmsapi.CreateSignerRequest) (crypto.Signer, error) {
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if err := c.initializeKeyManager(); err != nil {
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return nil, err
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}
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return c.KeyManager.CreateSigner(req)
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}
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// createCertificate sets the SignatureAlgorithm of the template if necessary
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// and calls x509util.CreateCertificate.
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func createCertificate(template, parent *x509.Certificate, pub crypto.PublicKey, signer crypto.Signer) (*x509.Certificate, error) {
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// Signers can specify the signature algorithm. This is especially important
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// when x509.CreateCertificate attempts to validate a RSAPSS signature.
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if template.SignatureAlgorithm == 0 {
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if sa, ok := signer.(apiv1.SignatureAlgorithmGetter); ok {
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template.SignatureAlgorithm = sa.SignatureAlgorithm()
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} else if _, ok := parent.PublicKey.(*rsa.PublicKey); ok {
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// For RSA issuers, only overwrite the default algorithm is the
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// intermediate is signed with an RSA signature scheme.
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if isRSA(parent.SignatureAlgorithm) {
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template.SignatureAlgorithm = parent.SignatureAlgorithm
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}
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}
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}
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return x509util.CreateCertificate(template, parent, pub, signer)
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}
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func isRSA(sa x509.SignatureAlgorithm) bool {
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switch sa {
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case x509.SHA256WithRSA, x509.SHA384WithRSA, x509.SHA512WithRSA:
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return true
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case x509.SHA256WithRSAPSS, x509.SHA384WithRSAPSS, x509.SHA512WithRSAPSS:
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return true
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default:
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return false
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}
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}
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