traefik/middlewares/tlsClientHeaders.go

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2018-08-29 09:36:03 +00:00
package middlewares
import (
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"net/http"
"net/url"
"strings"
"github.com/containous/traefik/log"
"github.com/containous/traefik/types"
)
const xForwardedTLSClientCert = "X-Forwarded-Tls-Client-Cert"
const xForwardedTLSClientCertInfos = "X-Forwarded-Tls-Client-Cert-Infos"
// TLSClientCertificateInfos is a struct for specifying the configuration for the tlsClientHeaders middleware.
type TLSClientCertificateInfos struct {
NotAfter bool
NotBefore bool
Subject *TLSCLientCertificateSubjectInfos
Sans bool
}
// TLSCLientCertificateSubjectInfos contains the configuration for the certificate subject infos.
type TLSCLientCertificateSubjectInfos struct {
Country bool
Province bool
Locality bool
Organization bool
CommonName bool
SerialNumber bool
}
// TLSClientHeaders is a middleware that helps setup a few tls infos features.
type TLSClientHeaders struct {
PEM bool // pass the sanitized pem to the backend in a specific header
Infos *TLSClientCertificateInfos // pass selected informations from the client certificate
}
func newTLSCLientCertificateSubjectInfos(infos *types.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 newTLSClientInfos(infos *types.TLSClientCertificateInfos) *TLSClientCertificateInfos {
if infos == nil {
return nil
}
return &TLSClientCertificateInfos{
NotBefore: infos.NotBefore,
NotAfter: infos.NotAfter,
Sans: infos.Sans,
Subject: newTLSCLientCertificateSubjectInfos(infos.Subject),
}
}
// NewTLSClientHeaders constructs a new TLSClientHeaders instance from supplied frontend header struct.
func NewTLSClientHeaders(frontend *types.Frontend) *TLSClientHeaders {
if frontend == nil {
return nil
}
var pem bool
var infos *TLSClientCertificateInfos
if frontend.PassTLSClientCert != nil {
conf := frontend.PassTLSClientCert
pem = conf.PEM
infos = newTLSClientInfos(conf.Infos)
}
return &TLSClientHeaders{
PEM: pem,
Infos: infos,
}
}
func (s *TLSClientHeaders) ServeHTTP(w http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
s.ModifyRequestHeaders(r)
// If there is a next, call it.
if next != nil {
next(w, r)
}
}
// 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(cert *x509.Certificate) string {
b := pem.Block{Type: "CERTIFICATE", Bytes: cert.Raw}
certPEM := pem.EncodeToMemory(&b)
if certPEM == nil {
log.Error("Cannot extract the certificate content")
return ""
}
return sanitize(certPEM)
}
// getXForwardedTLSClientCert Build a string with the client certificates
func getXForwardedTLSClientCert(certs []*x509.Certificate) string {
var headerValues []string
for _, peerCert := range certs {
headerValues = append(headerValues, extractCertificate(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...)
}
// getSubjectInfos extract the requested informations from the certificate subject
func (s *TLSClientHeaders) getSubjectInfos(cs *pkix.Name) string {
var subject string
if s.Infos != nil && s.Infos.Subject != nil {
options := s.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 informations
// like Subject="C=%s,ST=%s,L=%s,O=%s,CN=%s",NB=%d,NA=%d,SAN=%s;
func (s *TLSClientHeaders) 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 := s.getSubjectInfos(&peerCert.Subject)
if len(subject) > 0 {
values = append(values, subject)
}
ci := s.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 informations
func (s *TLSClientHeaders) ModifyRequestHeaders(r *http.Request) {
if s.PEM {
if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 {
r.Header.Set(xForwardedTLSClientCert, getXForwardedTLSClientCert(r.TLS.PeerCertificates))
} else {
log.Warn("Try to extract certificate on a request without TLS")
}
}
if s.Infos != nil {
if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 {
headerContent := s.getXForwardedTLSClientCertInfos(r.TLS.PeerCertificates)
r.Header.Set(xForwardedTLSClientCertInfos, url.QueryEscape(headerContent))
} else {
log.Warn("Try to extract certificate on a request without TLS")
}
}
}