func parseAndVerifyCertChain(x5c []string, roots *x509.CertPool) (leafKey libtrust.PublicKey, err error) {
if len(x5c) == 0 {
return nil, errors.New("empty x509 certificate chain")
}
// Ensure the first element is encoded correctly.
leafCertDer, err := base64.StdEncoding.DecodeString(x5c[0])
if err != nil {
return nil, fmt.Errorf("unable to decode leaf certificate: %s", err)
}
// And that it is a valid x509 certificate.
leafCert, err := x509.ParseCertificate(leafCertDer)
if err != nil {
return nil, fmt.Errorf("unable to parse leaf certificate: %s", err)
}
// The rest of the certificate chain are intermediate certificates.
intermediates := x509.NewCertPool()
for i := 1; i < len(x5c); i++ {
intermediateCertDer, err := base64.StdEncoding.DecodeString(x5c[i])
if err != nil {
return nil, fmt.Errorf("unable to decode intermediate certificate: %s", err)
}
intermediateCert, err := x509.ParseCertificate(intermediateCertDer)
if err != nil {
return nil, fmt.Errorf("unable to parse intermediate certificate: %s", err)
}
intermediates.AddCert(intermediateCert)
}
verifyOpts := x509.VerifyOptions{
Intermediates: intermediates,
Roots: roots,
KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageAny},
}
// TODO: this call returns certificate chains which we ignore for now, but
// we should check them for revocations if we have the ability later.
if _, err = leafCert.Verify(verifyOpts); err != nil {
return nil, fmt.Errorf("unable to verify certificate chain: %s", err)
}
// Get the public key from the leaf certificate.
leafCryptoKey, ok := leafCert.PublicKey.(crypto.PublicKey)
if !ok {
return nil, errors.New("unable to get leaf cert public key value")
}
leafKey, err = libtrust.FromCryptoPublicKey(leafCryptoKey)
if err != nil {
return nil, fmt.Errorf("unable to make libtrust public key from leaf certificate: %s", err)
}
return
}
// newAccessController creates an accessController using the given options.
func newAccessController(options map[string]interface{}) (auth.AccessController, error) {
config, err := checkOptions(options)
if err != nil {
return nil, err
}
fp, err := os.Open(config.rootCertBundle)
if err != nil {
return nil, fmt.Errorf("unable to open token auth root certificate bundle file %q: %s", config.rootCertBundle, err)
}
defer fp.Close()
rawCertBundle, err := ioutil.ReadAll(fp)
if err != nil {
return nil, fmt.Errorf("unable to read token auth root certificate bundle file %q: %s", config.rootCertBundle, err)
}
var rootCerts []*x509.Certificate
pemBlock, rawCertBundle := pem.Decode(rawCertBundle)
for pemBlock != nil {
cert, err := x509.ParseCertificate(pemBlock.Bytes)
if err != nil {
return nil, fmt.Errorf("unable to parse token auth root certificate: %s", err)
}
rootCerts = append(rootCerts, cert)
pemBlock, rawCertBundle = pem.Decode(rawCertBundle)
}
if len(rootCerts) == 0 {
return nil, errors.New("token auth requires at least one token signing root certificate")
}
rootPool := x509.NewCertPool()
trustedKeys := make(map[string]libtrust.PublicKey, len(rootCerts))
for _, rootCert := range rootCerts {
rootPool.AddCert(rootCert)
pubKey, err := libtrust.FromCryptoPublicKey(crypto.PublicKey(rootCert.PublicKey))
if err != nil {
return nil, fmt.Errorf("unable to get public key from token auth root certificate: %s", err)
}
trustedKeys[pubKey.KeyID()] = pubKey
}
return &accessController{
realm: config.realm,
issuer: config.issuer,
service: config.service,
rootCerts: rootPool,
trustedKeys: trustedKeys,
}, nil
}