traefik/middlewares/passtlsclientcert/pass_tls_client_cert.go
2018-11-14 10:18:03 +01:00

253 lines
7 KiB
Go

package passtlsclientcert
import (
"context"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"net/http"
"net/url"
"strings"
"github.com/containous/traefik/config"
"github.com/containous/traefik/middlewares"
"github.com/containous/traefik/tracing"
"github.com/opentracing/opentracing-go/ext"
"github.com/sirupsen/logrus"
)
const (
xForwardedTLSClientCert = "X-Forwarded-Tls-Client-Cert"
xForwardedTLSClientCertInfos = "X-Forwarded-Tls-Client-Cert-infos"
typeName = "PassClientTLSCert"
)
// passTLSClientCert is a middleware that helps setup a few tls info features.
type passTLSClientCert struct {
next http.Handler
name string
pem bool // pass the sanitized pem to the backend in a specific header
infos *tlsClientCertificateInfos // pass selected information from the client certificate
}
// New constructs a new PassTLSClientCert instance from supplied frontend header struct.
func New(ctx context.Context, next http.Handler, config config.PassTLSClientCert, name string) (http.Handler, error) {
middlewares.GetLogger(ctx, name, typeName).Debug("Creating middleware")
return &passTLSClientCert{
next: next,
name: name,
pem: config.PEM,
infos: newTLSClientInfos(config.Infos),
}, nil
}
// tlsClientCertificateInfos is a struct for specifying the configuration for the passTLSClientCert middleware.
type tlsClientCertificateInfos struct {
notAfter bool
notBefore bool
subject *tlsCLientCertificateSubjectInfos
sans bool
}
func newTLSClientInfos(infos *config.TLSClientCertificateInfos) *tlsClientCertificateInfos {
if infos == nil {
return nil
}
return &tlsClientCertificateInfos{
notBefore: infos.NotBefore,
notAfter: infos.NotAfter,
sans: infos.Sans,
subject: newTLSCLientCertificateSubjectInfos(infos.Subject),
}
}
// tlsCLientCertificateSubjectInfos contains the configuration for the certificate subject infos.
type tlsCLientCertificateSubjectInfos struct {
country bool
province bool
locality bool
Organization bool
commonName bool
serialNumber bool
}
func newTLSCLientCertificateSubjectInfos(infos *config.TLSCLientCertificateSubjectInfos) *tlsCLientCertificateSubjectInfos {
if infos == nil {
return nil
}
return &tlsCLientCertificateSubjectInfos{
serialNumber: infos.SerialNumber,
commonName: infos.CommonName,
country: infos.Country,
locality: infos.Locality,
Organization: infos.Organization,
province: infos.Province,
}
}
func (p *passTLSClientCert) GetTracingInformation() (string, ext.SpanKindEnum) {
return p.name, tracing.SpanKindNoneEnum
}
func (p *passTLSClientCert) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
logger := middlewares.GetLogger(req.Context(), p.name, typeName)
p.modifyRequestHeaders(logger, req)
p.next.ServeHTTP(rw, req)
}
// getSubjectInfos extract the requested information from the certificate subject.
func (p *passTLSClientCert) getSubjectInfos(cs *pkix.Name) string {
var subject string
if p.infos != nil && p.infos.subject != nil {
options := p.infos.subject
var content []string
if options.country && len(cs.Country) > 0 {
content = append(content, fmt.Sprintf("C=%s", cs.Country[0]))
}
if options.province && len(cs.Province) > 0 {
content = append(content, fmt.Sprintf("ST=%s", cs.Province[0]))
}
if options.locality && len(cs.Locality) > 0 {
content = append(content, fmt.Sprintf("L=%s", cs.Locality[0]))
}
if options.Organization && len(cs.Organization) > 0 {
content = append(content, fmt.Sprintf("O=%s", cs.Organization[0]))
}
if options.commonName && len(cs.CommonName) > 0 {
content = append(content, fmt.Sprintf("CN=%s", cs.CommonName))
}
if len(content) > 0 {
subject = `Subject="` + strings.Join(content, ",") + `"`
}
}
return subject
}
// getXForwardedTLSClientCertInfos Build a string with the wanted client certificates information
// like Subject="C=%s,ST=%s,L=%s,O=%s,CN=%s",NB=%d,NA=%d,SAN=%s;
func (p *passTLSClientCert) getXForwardedTLSClientCertInfos(certs []*x509.Certificate) string {
var headerValues []string
for _, peerCert := range certs {
var values []string
var sans string
var nb string
var na string
subject := p.getSubjectInfos(&peerCert.Subject)
if len(subject) > 0 {
values = append(values, subject)
}
ci := p.infos
if ci != nil {
if ci.notBefore {
nb = fmt.Sprintf("NB=%d", uint64(peerCert.NotBefore.Unix()))
values = append(values, nb)
}
if ci.notAfter {
na = fmt.Sprintf("NA=%d", uint64(peerCert.NotAfter.Unix()))
values = append(values, na)
}
if ci.sans {
sans = fmt.Sprintf("SAN=%s", strings.Join(getSANs(peerCert), ","))
values = append(values, sans)
}
}
value := strings.Join(values, ",")
headerValues = append(headerValues, value)
}
return strings.Join(headerValues, ";")
}
// modifyRequestHeaders set the wanted headers with the certificates information.
func (p *passTLSClientCert) modifyRequestHeaders(logger logrus.FieldLogger, r *http.Request) {
if p.pem {
if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 {
r.Header.Set(xForwardedTLSClientCert, getXForwardedTLSClientCert(logger, r.TLS.PeerCertificates))
} else {
logger.Warn("Try to extract certificate on a request without TLS")
}
}
if p.infos != nil {
if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 {
headerContent := p.getXForwardedTLSClientCertInfos(r.TLS.PeerCertificates)
r.Header.Set(xForwardedTLSClientCertInfos, url.QueryEscape(headerContent))
} else {
logger.Warn("Try to extract certificate on a request without TLS")
}
}
}
// sanitize As we pass the raw certificates, remove the useless data and make it http request compliant.
func sanitize(cert []byte) string {
s := string(cert)
r := strings.NewReplacer("-----BEGIN CERTIFICATE-----", "",
"-----END CERTIFICATE-----", "",
"\n", "")
cleaned := r.Replace(s)
return url.QueryEscape(cleaned)
}
// extractCertificate extract the certificate from the request.
func extractCertificate(logger logrus.FieldLogger, cert *x509.Certificate) string {
b := pem.Block{Type: "CERTIFICATE", Bytes: cert.Raw}
certPEM := pem.EncodeToMemory(&b)
if certPEM == nil {
logger.Error("Cannot extract the certificate content")
return ""
}
return sanitize(certPEM)
}
// getXForwardedTLSClientCert Build a string with the client certificates.
func getXForwardedTLSClientCert(logger logrus.FieldLogger, certs []*x509.Certificate) string {
var headerValues []string
for _, peerCert := range certs {
headerValues = append(headerValues, extractCertificate(logger, peerCert))
}
return strings.Join(headerValues, ",")
}
// getSANs get the Subject Alternate Name values.
func getSANs(cert *x509.Certificate) []string {
var sans []string
if cert == nil {
return sans
}
sans = append(cert.DNSNames, cert.EmailAddresses...)
var ips []string
for _, ip := range cert.IPAddresses {
ips = append(ips, ip.String())
}
sans = append(sans, ips...)
var uris []string
for _, uri := range cert.URIs {
uris = append(uris, uri.String())
}
return append(sans, uris...)
}