package cloudcas import ( "crypto" "crypto/ecdsa" "crypto/rsa" "crypto/x509" "crypto/x509/pkix" "encoding/asn1" "encoding/pem" "fmt" "github.com/pkg/errors" kmsapi "github.com/smallstep/certificates/kms/apiv1" pb "google.golang.org/genproto/googleapis/cloud/security/privateca/v1" ) var ( oidExtensionSubjectKeyID = []int{2, 5, 29, 14} oidExtensionKeyUsage = []int{2, 5, 29, 15} oidExtensionExtendedKeyUsage = []int{2, 5, 29, 37} oidExtensionAuthorityKeyID = []int{2, 5, 29, 35} oidExtensionBasicConstraints = []int{2, 5, 29, 19} oidExtensionSubjectAltName = []int{2, 5, 29, 17} oidExtensionCRLDistributionPoints = []int{2, 5, 29, 31} oidExtensionCertificatePolicies = []int{2, 5, 29, 32} oidExtensionAuthorityInfoAccess = []int{1, 3, 6, 1, 5, 5, 7, 1, 1} ) var extraExtensions = [...]asn1.ObjectIdentifier{ oidExtensionSubjectKeyID, // Added by CAS oidExtensionKeyUsage, // Added in CertificateConfig.ReusableConfig oidExtensionExtendedKeyUsage, // Added in CertificateConfig.ReusableConfig oidExtensionAuthorityKeyID, // Added by CAS oidExtensionBasicConstraints, // Added in CertificateConfig.ReusableConfig oidExtensionSubjectAltName, // Added in CertificateConfig.SubjectConfig.SubjectAltName oidExtensionCRLDistributionPoints, // Added by CAS oidExtensionCertificatePolicies, // Added in CertificateConfig.ReusableConfig oidExtensionAuthorityInfoAccess, // Added in CertificateConfig.ReusableConfig and by CAS } var ( oidExtKeyUsageAny = asn1.ObjectIdentifier{2, 5, 29, 37, 0} oidExtKeyUsageIPSECEndSystem = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 5} oidExtKeyUsageIPSECTunnel = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 6} oidExtKeyUsageIPSECUser = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 7} oidExtKeyUsageMicrosoftServerGatedCrypto = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 10, 3, 3} oidExtKeyUsageNetscapeServerGatedCrypto = asn1.ObjectIdentifier{2, 16, 840, 1, 113730, 4, 1} oidExtKeyUsageMicrosoftCommercialCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 2, 1, 22} oidExtKeyUsageMicrosoftKernelCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 61, 1, 1} ) const ( nameTypeEmail = 1 nameTypeDNS = 2 nameTypeURI = 6 nameTypeIP = 7 ) func createCertificateConfig(tpl *x509.Certificate) (*pb.Certificate_Config, error) { pk, err := createPublicKey(tpl.PublicKey) if err != nil { return nil, err } config := &pb.CertificateConfig{ SubjectConfig: &pb.CertificateConfig_SubjectConfig{ Subject: createSubject(tpl), SubjectAltName: createSubjectAlternativeNames(tpl), }, X509Config: createX509Parameters(tpl), PublicKey: pk, } return &pb.Certificate_Config{ Config: config, }, nil } func createPublicKey(key crypto.PublicKey) (*pb.PublicKey, error) { switch key := key.(type) { case *ecdsa.PublicKey: asn1Bytes, err := x509.MarshalPKIXPublicKey(key) if err != nil { return nil, errors.Wrap(err, "error marshaling public key") } return &pb.PublicKey{ Format: pb.PublicKey_PEM, Key: pem.EncodeToMemory(&pem.Block{ Type: "PUBLIC KEY", Bytes: asn1Bytes, }), }, nil case *rsa.PublicKey: return &pb.PublicKey{ Format: pb.PublicKey_PEM, Key: pem.EncodeToMemory(&pem.Block{ Type: "RSA PUBLIC KEY", Bytes: x509.MarshalPKCS1PublicKey(key), }), }, nil default: return nil, errors.Errorf("unsupported public key type: %T", key) } } func createSubject(cert *x509.Certificate) *pb.Subject { sub := cert.Subject ret := &pb.Subject{ CommonName: sub.CommonName, } if len(sub.Country) > 0 { ret.CountryCode = sub.Country[0] } if len(sub.Organization) > 0 { ret.Organization = sub.Organization[0] } if len(sub.OrganizationalUnit) > 0 { ret.OrganizationalUnit = sub.OrganizationalUnit[0] } if len(sub.Locality) > 0 { ret.Locality = sub.Locality[0] } if len(sub.Province) > 0 { ret.Province = sub.Province[0] } if len(sub.StreetAddress) > 0 { ret.StreetAddress = sub.StreetAddress[0] } if len(sub.PostalCode) > 0 { ret.PostalCode = sub.PostalCode[0] } return ret } func createSubjectAlternativeNames(cert *x509.Certificate) *pb.SubjectAltNames { ret := new(pb.SubjectAltNames) ret.DnsNames = cert.DNSNames ret.EmailAddresses = cert.EmailAddresses if n := len(cert.IPAddresses); n > 0 { ret.IpAddresses = make([]string, n) for i, ip := range cert.IPAddresses { ret.IpAddresses[i] = ip.String() } } if n := len(cert.URIs); n > 0 { ret.Uris = make([]string, n) for i, u := range cert.URIs { ret.Uris[i] = u.String() } } // Add extra SANs coming from the extensions if ext, ok := findExtraExtension(cert, oidExtensionSubjectAltName); ok { var rawValues []asn1.RawValue if _, err := asn1.Unmarshal(ext.Value, &rawValues); err == nil { var newValues []asn1.RawValue for _, v := range rawValues { if v.Class == asn1.ClassContextSpecific { switch v.Tag { case nameTypeDNS: if len(ret.DnsNames) == 0 { newValues = append(newValues, v) } case nameTypeEmail: if len(ret.EmailAddresses) == 0 { newValues = append(newValues, v) } case nameTypeIP: if len(ret.IpAddresses) == 0 { newValues = append(newValues, v) } case nameTypeURI: if len(ret.Uris) == 0 { newValues = append(newValues, v) } default: newValues = append(newValues, v) } } else { newValues = append(newValues, v) } } if len(newValues) > 0 { if b, err := asn1.Marshal(newValues); err == nil { ret.CustomSans = []*pb.X509Extension{{ ObjectId: createObjectID(ext.Id), Critical: ext.Critical, Value: b, }} } } } } return ret } func createX509Parameters(cert *x509.Certificate) *pb.X509Parameters { var unknownEKUs []*pb.ObjectId var ekuOptions = &pb.KeyUsage_ExtendedKeyUsageOptions{} for _, eku := range cert.ExtKeyUsage { switch eku { case x509.ExtKeyUsageAny: unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageAny)) case x509.ExtKeyUsageServerAuth: ekuOptions.ServerAuth = true case x509.ExtKeyUsageClientAuth: ekuOptions.ClientAuth = true case x509.ExtKeyUsageCodeSigning: ekuOptions.CodeSigning = true case x509.ExtKeyUsageEmailProtection: ekuOptions.EmailProtection = true case x509.ExtKeyUsageIPSECEndSystem: unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageIPSECEndSystem)) case x509.ExtKeyUsageIPSECTunnel: unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageIPSECTunnel)) case x509.ExtKeyUsageIPSECUser: unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageIPSECUser)) case x509.ExtKeyUsageTimeStamping: ekuOptions.TimeStamping = true case x509.ExtKeyUsageOCSPSigning: ekuOptions.OcspSigning = true case x509.ExtKeyUsageMicrosoftServerGatedCrypto: unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageMicrosoftServerGatedCrypto)) case x509.ExtKeyUsageNetscapeServerGatedCrypto: unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageNetscapeServerGatedCrypto)) case x509.ExtKeyUsageMicrosoftCommercialCodeSigning: unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageMicrosoftCommercialCodeSigning)) case x509.ExtKeyUsageMicrosoftKernelCodeSigning: unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageMicrosoftKernelCodeSigning)) } } for _, oid := range cert.UnknownExtKeyUsage { unknownEKUs = append(unknownEKUs, createObjectID(oid)) } var policyIDs []*pb.ObjectId for _, oid := range cert.PolicyIdentifiers { policyIDs = append(policyIDs, createObjectID(oid)) } var caOptions *pb.X509Parameters_CaOptions if cert.BasicConstraintsValid { caOptions = new(pb.X509Parameters_CaOptions) var maxPathLength int32 switch { case cert.MaxPathLenZero: maxPathLength = 0 caOptions.MaxIssuerPathLength = &maxPathLength case cert.MaxPathLen > 0: maxPathLength = int32(cert.MaxPathLen) caOptions.MaxIssuerPathLength = &maxPathLength } caOptions.IsCa = &cert.IsCA } var extraExtensions []*pb.X509Extension for _, ext := range cert.ExtraExtensions { if isExtraExtension(ext.Id) { extraExtensions = append(extraExtensions, &pb.X509Extension{ ObjectId: createObjectID(ext.Id), Critical: ext.Critical, Value: ext.Value, }) } } return &pb.X509Parameters{ KeyUsage: &pb.KeyUsage{ BaseKeyUsage: &pb.KeyUsage_KeyUsageOptions{ DigitalSignature: cert.KeyUsage&x509.KeyUsageDigitalSignature > 0, ContentCommitment: cert.KeyUsage&x509.KeyUsageContentCommitment > 0, KeyEncipherment: cert.KeyUsage&x509.KeyUsageKeyEncipherment > 0, DataEncipherment: cert.KeyUsage&x509.KeyUsageDataEncipherment > 0, KeyAgreement: cert.KeyUsage&x509.KeyUsageKeyAgreement > 0, CertSign: cert.KeyUsage&x509.KeyUsageCertSign > 0, CrlSign: cert.KeyUsage&x509.KeyUsageCRLSign > 0, EncipherOnly: cert.KeyUsage&x509.KeyUsageEncipherOnly > 0, DecipherOnly: cert.KeyUsage&x509.KeyUsageDecipherOnly > 0, }, ExtendedKeyUsage: ekuOptions, UnknownExtendedKeyUsages: unknownEKUs, }, CaOptions: caOptions, PolicyIds: policyIDs, AiaOcspServers: cert.OCSPServer, AdditionalExtensions: extraExtensions, } } // isExtraExtension returns true if the extension oid is not managed in a // different way. func isExtraExtension(oid asn1.ObjectIdentifier) bool { for _, id := range extraExtensions { if id.Equal(oid) { return false } } return true } func createObjectID(oid asn1.ObjectIdentifier) *pb.ObjectId { ret := make([]int32, len(oid)) for i, v := range oid { ret[i] = int32(v) } return &pb.ObjectId{ ObjectIdPath: ret, } } func findExtraExtension(cert *x509.Certificate, oid asn1.ObjectIdentifier) (pkix.Extension, bool) { for _, ext := range cert.ExtraExtensions { if ext.Id.Equal(oid) { return ext, true } } return pkix.Extension{}, false } func createKeyVersionSpec(alg kmsapi.SignatureAlgorithm, bits int) (*pb.CertificateAuthority_KeyVersionSpec, error) { switch alg { case kmsapi.UnspecifiedSignAlgorithm, kmsapi.ECDSAWithSHA256: return &pb.CertificateAuthority_KeyVersionSpec{ KeyVersion: &pb.CertificateAuthority_KeyVersionSpec_Algorithm{ Algorithm: pb.CertificateAuthority_EC_P256_SHA256, }, }, nil case kmsapi.ECDSAWithSHA384: return &pb.CertificateAuthority_KeyVersionSpec{ KeyVersion: &pb.CertificateAuthority_KeyVersionSpec_Algorithm{ Algorithm: pb.CertificateAuthority_EC_P384_SHA384, }, }, nil case kmsapi.SHA256WithRSA: algo, err := getRSAPKCS1Algorithm(bits) if err != nil { return nil, err } return &pb.CertificateAuthority_KeyVersionSpec{ KeyVersion: &pb.CertificateAuthority_KeyVersionSpec_Algorithm{ Algorithm: algo, }, }, nil case kmsapi.SHA256WithRSAPSS: algo, err := getRSAPSSAlgorithm(bits) if err != nil { return nil, err } return &pb.CertificateAuthority_KeyVersionSpec{ KeyVersion: &pb.CertificateAuthority_KeyVersionSpec_Algorithm{ Algorithm: algo, }, }, nil default: return nil, fmt.Errorf("unknown or unsupported signature algorithm '%s'", alg) } } func getRSAPKCS1Algorithm(bits int) (pb.CertificateAuthority_SignHashAlgorithm, error) { switch bits { case 0, 3072: return pb.CertificateAuthority_RSA_PKCS1_3072_SHA256, nil case 2048: return pb.CertificateAuthority_RSA_PKCS1_2048_SHA256, nil case 4096: return pb.CertificateAuthority_RSA_PKCS1_4096_SHA256, nil default: return 0, fmt.Errorf("unsupported RSA PKCS #1 key size '%d'", bits) } } func getRSAPSSAlgorithm(bits int) (pb.CertificateAuthority_SignHashAlgorithm, error) { switch bits { case 0, 3072: return pb.CertificateAuthority_RSA_PSS_3072_SHA256, nil case 2048: return pb.CertificateAuthority_RSA_PSS_2048_SHA256, nil case 4096: return pb.CertificateAuthority_RSA_PSS_4096_SHA256, nil default: return 0, fmt.Errorf("unsupported RSA-PSS key size '%d'", bits) } }