// VerifyCSR checks the validity of a x509.CertificateRequest. Before doing checks it normalizes
// the CSR which lowers the case of DNS names and subject CN, and if forceCNFromSAN is true it
// will hoist a DNS name into the CN if it is empty.
func VerifyCSR(csr *x509.CertificateRequest, maxNames int, keyPolicy *goodkey.KeyPolicy, pa core.PolicyAuthority, forceCNFromSAN bool, regID int64) error {
normalizeCSR(csr, forceCNFromSAN)
key, ok := csr.PublicKey.(crypto.PublicKey)
if !ok {
return invalidPubKey
}
if err := keyPolicy.GoodKey(key); err != nil {
return fmt.Errorf("invalid public key in CSR: %s", err)
}
if badSignatureAlgorithms[csr.SignatureAlgorithm] {
// go1.6 provides a stringer for x509.SignatureAlgorithm but 1.5.x
// does not
return unsupportedSigAlg
}
if err := csr.CheckSignature(); err != nil {
return invalidSig
}
if len(csr.EmailAddresses) > 0 {
return invalidEmailPresent
}
if len(csr.IPAddresses) > 0 {
return invalidIPPresent
}
if len(csr.DNSNames) == 0 && csr.Subject.CommonName == "" {
return invalidNoDNS
}
if len(csr.Subject.CommonName) > maxCNLength {
return fmt.Errorf("CN was longer than %d bytes", maxCNLength)
}
if maxNames > 0 && len(csr.DNSNames) > maxNames {
return fmt.Errorf("CSR contains more than %d DNS names", maxNames)
}
badNames := []string{}
for _, name := range csr.DNSNames {
if err := pa.WillingToIssue(core.AcmeIdentifier{
Type: core.IdentifierDNS,
Value: name,
}); err != nil {
badNames = append(badNames, fmt.Sprintf("%q", name))
}
}
if len(badNames) > 0 {
return fmt.Errorf("policy forbids issuing for: %s", strings.Join(badNames, ", "))
}
return nil
}
// Performs the heavy lifting of generating a certificate from a CSR.
// Returns a ParsedCertBundle sans private keys.
func signCertificate(creationInfo *creationBundle,
csr *x509.CertificateRequest) (*certutil.ParsedCertBundle, error) {
switch {
case creationInfo == nil:
return nil, errutil.UserError{Err: "nil creation info given to signCertificate"}
case creationInfo.SigningBundle == nil:
return nil, errutil.UserError{Err: "nil signing bundle given to signCertificate"}
case csr == nil:
return nil, errutil.UserError{Err: "nil csr given to signCertificate"}
}
err := csr.CheckSignature()
if err != nil {
return nil, errutil.UserError{Err: "request signature invalid"}
}
result := &certutil.ParsedCertBundle{}
serialNumber, err := certutil.GenerateSerialNumber()
if err != nil {
return nil, err
}
marshaledKey, err := x509.MarshalPKIXPublicKey(csr.PublicKey)
if err != nil {
return nil, errutil.InternalError{Err: fmt.Sprintf("error marshalling public key: %s", err)}
}
subjKeyID := sha1.Sum(marshaledKey)
subject := pkix.Name{
CommonName: creationInfo.CommonName,
}
certTemplate := &x509.Certificate{
SerialNumber: serialNumber,
Subject: subject,
NotBefore: time.Now().Add(-30 * time.Second),
NotAfter: time.Now().Add(creationInfo.TTL),
SubjectKeyId: subjKeyID[:],
}
switch creationInfo.SigningBundle.PrivateKeyType {
case certutil.RSAPrivateKey:
certTemplate.SignatureAlgorithm = x509.SHA256WithRSA
case certutil.ECPrivateKey:
certTemplate.SignatureAlgorithm = x509.ECDSAWithSHA256
}
if creationInfo.UseCSRValues {
certTemplate.Subject = csr.Subject
certTemplate.DNSNames = csr.DNSNames
certTemplate.EmailAddresses = csr.EmailAddresses
certTemplate.IPAddresses = csr.IPAddresses
certTemplate.ExtraExtensions = csr.Extensions
} else {
certTemplate.DNSNames = creationInfo.DNSNames
certTemplate.EmailAddresses = creationInfo.EmailAddresses
certTemplate.IPAddresses = creationInfo.IPAddresses
}
addKeyUsages(creationInfo, certTemplate)
var certBytes []byte
caCert := creationInfo.SigningBundle.Certificate
certTemplate.IssuingCertificateURL = creationInfo.URLs.IssuingCertificates
certTemplate.CRLDistributionPoints = creationInfo.URLs.CRLDistributionPoints
certTemplate.OCSPServer = creationInfo.SigningBundle.URLs.OCSPServers
if creationInfo.IsCA {
certTemplate.BasicConstraintsValid = true
certTemplate.IsCA = true
if creationInfo.SigningBundle.Certificate.MaxPathLen == 0 &&
creationInfo.SigningBundle.Certificate.MaxPathLenZero {
return nil, errutil.UserError{Err: "signing certificate has a max path length of zero, and cannot issue further CA certificates"}
}
certTemplate.MaxPathLen = creationInfo.MaxPathLength
if certTemplate.MaxPathLen == 0 {
certTemplate.MaxPathLenZero = true
}
}
certBytes, err = x509.CreateCertificate(rand.Reader, certTemplate, caCert, csr.PublicKey, creationInfo.SigningBundle.PrivateKey)
if err != nil {
return nil, errutil.InternalError{Err: fmt.Sprintf("unable to create certificate: %s", err)}
}
result.CertificateBytes = certBytes
result.Certificate, err = x509.ParseCertificate(certBytes)
if err != nil {
return nil, errutil.InternalError{Err: fmt.Sprintf("unable to parse created certificate: %s", err)}
}
result.IssuingCABytes = creationInfo.SigningBundle.CertificateBytes
result.IssuingCA = creationInfo.SigningBundle.Certificate
return result, nil
}
// Performs the heavy lifting of generating a certificate from a CSR.
// Returns a ParsedCertBundle sans private keys.
func signCertificate(creationInfo *creationBundle,
csr *x509.CertificateRequest) (*certutil.ParsedCertBundle, error) {
switch {
case creationInfo == nil:
return nil, certutil.UserError{Err: "nil creation info given to signCertificate"}
case creationInfo.SigningBundle == nil:
return nil, certutil.UserError{Err: "nil signing bundle given to signCertificate"}
case csr == nil:
return nil, certutil.UserError{Err: "nil csr given to signCertificate"}
}
err := csr.CheckSignature()
if err != nil {
return nil, certutil.UserError{Err: "request signature invalid"}
}
result := &certutil.ParsedCertBundle{}
serialNumber, err := certutil.GenerateSerialNumber()
if err != nil {
return nil, err
}
marshaledKey, err := x509.MarshalPKIXPublicKey(csr.PublicKey)
if err != nil {
return nil, certutil.InternalError{Err: fmt.Sprintf("error marshalling public key: %s", err)}
}
subjKeyID := sha1.Sum(marshaledKey)
subject := pkix.Name{
CommonName: creationInfo.CommonName,
}
certTemplate := &x509.Certificate{
SerialNumber: serialNumber,
Subject: subject,
NotBefore: time.Now(),
NotAfter: time.Now().Add(creationInfo.TTL),
SubjectKeyId: subjKeyID[:],
}
switch creationInfo.SigningBundle.PrivateKeyType {
case certutil.RSAPrivateKey:
certTemplate.SignatureAlgorithm = x509.SHA256WithRSA
case certutil.ECPrivateKey:
certTemplate.SignatureAlgorithm = x509.ECDSAWithSHA256
}
if creationInfo.UseCSRValues {
certTemplate.Subject = csr.Subject
certTemplate.DNSNames = csr.DNSNames
certTemplate.EmailAddresses = csr.EmailAddresses
certTemplate.IPAddresses = csr.IPAddresses
certTemplate.ExtraExtensions = csr.Extensions
// Do not sign a CA certificate if they didn't go through the sign-intermediate
// endpoint
if !creationInfo.IsCA && oidInExtensions(oidExtensionBasicConstraints, certTemplate.ExtraExtensions) {
return nil, certutil.UserError{Err: "will not sign a CSR asking for CA rights through this endpoint"}
}
} else {
certTemplate.DNSNames = creationInfo.DNSNames
certTemplate.EmailAddresses = creationInfo.EmailAddresses
certTemplate.IPAddresses = creationInfo.IPAddresses
certTemplate.KeyUsage = x509.KeyUsage(x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment | x509.KeyUsageKeyAgreement)
if creationInfo.Usage&serverUsage != 0 {
certTemplate.ExtKeyUsage = append(certTemplate.ExtKeyUsage, x509.ExtKeyUsageServerAuth)
}
if creationInfo.Usage&clientUsage != 0 {
certTemplate.ExtKeyUsage = append(certTemplate.ExtKeyUsage, x509.ExtKeyUsageClientAuth)
}
if creationInfo.Usage&codeSigningUsage != 0 {
certTemplate.ExtKeyUsage = append(certTemplate.ExtKeyUsage, x509.ExtKeyUsageCodeSigning)
}
if creationInfo.Usage&emailProtectionUsage != 0 {
certTemplate.ExtKeyUsage = append(certTemplate.ExtKeyUsage, x509.ExtKeyUsageEmailProtection)
}
if creationInfo.IsCA {
certTemplate.KeyUsage = x509.KeyUsage(certTemplate.KeyUsage | x509.KeyUsageCertSign | x509.KeyUsageCRLSign)
certTemplate.ExtKeyUsage = append(certTemplate.ExtKeyUsage, x509.ExtKeyUsageOCSPSigning)
}
}
var certBytes []byte
caCert := creationInfo.SigningBundle.Certificate
certTemplate.IssuingCertificateURL = creationInfo.URLs.IssuingCertificates
certTemplate.CRLDistributionPoints = creationInfo.URLs.CRLDistributionPoints
certTemplate.OCSPServer = creationInfo.SigningBundle.URLs.OCSPServers
if creationInfo.IsCA {
certTemplate.BasicConstraintsValid = true
certTemplate.IsCA = true
if creationInfo.SigningBundle.Certificate.MaxPathLen == 0 &&
creationInfo.SigningBundle.Certificate.MaxPathLenZero {
return nil, certutil.UserError{Err: "signing certificate has a max path length of zero, and cannot issue further CA certificates"}
}
certTemplate.MaxPathLen = creationInfo.MaxPathLength
if certTemplate.MaxPathLen == 0 {
certTemplate.MaxPathLenZero = true
}
}
certBytes, err = x509.CreateCertificate(rand.Reader, certTemplate, caCert, csr.PublicKey, creationInfo.SigningBundle.PrivateKey)
if err != nil {
return nil, certutil.InternalError{Err: fmt.Sprintf("unable to create certificate: %s", err)}
}
result.CertificateBytes = certBytes
result.Certificate, err = x509.ParseCertificate(certBytes)
if err != nil {
return nil, certutil.InternalError{Err: fmt.Sprintf("unable to parse created certificate: %s", err)}
}
result.IssuingCABytes = creationInfo.SigningBundle.CertificateBytes
result.IssuingCA = creationInfo.SigningBundle.Certificate
return result, nil
}