| /* |
| Copyright 2014 The Kubernetes Authors. |
| |
| Licensed under the Apache License, Version 2.0 (the "License"); |
| you may not use this file except in compliance with the License. |
| You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| */ |
| |
| package x509 |
| |
| import ( |
| "crypto/x509" |
| "crypto/x509/pkix" |
| "encoding/asn1" |
| "fmt" |
| "net/http" |
| "time" |
| |
| "github.com/golang/glog" |
| "github.com/prometheus/client_golang/prometheus" |
| |
| utilerrors "k8s.io/apimachinery/pkg/util/errors" |
| "k8s.io/apimachinery/pkg/util/sets" |
| "k8s.io/apiserver/pkg/authentication/authenticator" |
| "k8s.io/apiserver/pkg/authentication/user" |
| ) |
| |
| var clientCertificateExpirationHistogram = prometheus.NewHistogram( |
| prometheus.HistogramOpts{ |
| Namespace: "apiserver", |
| Subsystem: "client", |
| Name: "certificate_expiration_seconds", |
| Help: "Distribution of the remaining lifetime on the certificate used to authenticate a request.", |
| Buckets: []float64{ |
| 0, |
| (6 * time.Hour).Seconds(), |
| (12 * time.Hour).Seconds(), |
| (24 * time.Hour).Seconds(), |
| (2 * 24 * time.Hour).Seconds(), |
| (4 * 24 * time.Hour).Seconds(), |
| (7 * 24 * time.Hour).Seconds(), |
| (30 * 24 * time.Hour).Seconds(), |
| (3 * 30 * 24 * time.Hour).Seconds(), |
| (6 * 30 * 24 * time.Hour).Seconds(), |
| (12 * 30 * 24 * time.Hour).Seconds(), |
| }, |
| }, |
| ) |
| |
| func init() { |
| prometheus.MustRegister(clientCertificateExpirationHistogram) |
| } |
| |
| // UserConversion defines an interface for extracting user info from a client certificate chain |
| type UserConversion interface { |
| User(chain []*x509.Certificate) (user.Info, bool, error) |
| } |
| |
| // UserConversionFunc is a function that implements the UserConversion interface. |
| type UserConversionFunc func(chain []*x509.Certificate) (user.Info, bool, error) |
| |
| // User implements x509.UserConversion |
| func (f UserConversionFunc) User(chain []*x509.Certificate) (user.Info, bool, error) { |
| return f(chain) |
| } |
| |
| // Authenticator implements request.Authenticator by extracting user info from verified client certificates |
| type Authenticator struct { |
| opts x509.VerifyOptions |
| user UserConversion |
| } |
| |
| // New returns a request.Authenticator that verifies client certificates using the provided |
| // VerifyOptions, and converts valid certificate chains into user.Info using the provided UserConversion |
| func New(opts x509.VerifyOptions, user UserConversion) *Authenticator { |
| return &Authenticator{opts, user} |
| } |
| |
| // AuthenticateRequest authenticates the request using presented client certificates |
| func (a *Authenticator) AuthenticateRequest(req *http.Request) (user.Info, bool, error) { |
| if req.TLS == nil || len(req.TLS.PeerCertificates) == 0 { |
| return nil, false, nil |
| } |
| |
| // Use intermediates, if provided |
| optsCopy := a.opts |
| if optsCopy.Intermediates == nil && len(req.TLS.PeerCertificates) > 1 { |
| optsCopy.Intermediates = x509.NewCertPool() |
| for _, intermediate := range req.TLS.PeerCertificates[1:] { |
| optsCopy.Intermediates.AddCert(intermediate) |
| } |
| } |
| |
| remaining := req.TLS.PeerCertificates[0].NotAfter.Sub(time.Now()) |
| clientCertificateExpirationHistogram.Observe(remaining.Seconds()) |
| chains, err := req.TLS.PeerCertificates[0].Verify(optsCopy) |
| if err != nil { |
| return nil, false, err |
| } |
| |
| var errlist []error |
| for _, chain := range chains { |
| user, ok, err := a.user.User(chain) |
| if err != nil { |
| errlist = append(errlist, err) |
| continue |
| } |
| |
| if ok { |
| return user, ok, err |
| } |
| } |
| return nil, false, utilerrors.NewAggregate(errlist) |
| } |
| |
| // Verifier implements request.Authenticator by verifying a client cert on the request, then delegating to the wrapped auth |
| type Verifier struct { |
| opts x509.VerifyOptions |
| auth authenticator.Request |
| |
| // allowedCommonNames contains the common names which a verified certificate is allowed to have. |
| // If empty, all verified certificates are allowed. |
| allowedCommonNames sets.String |
| } |
| |
| // NewVerifier create a request.Authenticator by verifying a client cert on the request, then delegating to the wrapped auth |
| func NewVerifier(opts x509.VerifyOptions, auth authenticator.Request, allowedCommonNames sets.String) authenticator.Request { |
| return &Verifier{opts, auth, allowedCommonNames} |
| } |
| |
| // AuthenticateRequest verifies the presented client certificate, then delegates to the wrapped auth |
| func (a *Verifier) AuthenticateRequest(req *http.Request) (user.Info, bool, error) { |
| if req.TLS == nil || len(req.TLS.PeerCertificates) == 0 { |
| return nil, false, nil |
| } |
| |
| // Use intermediates, if provided |
| optsCopy := a.opts |
| if optsCopy.Intermediates == nil && len(req.TLS.PeerCertificates) > 1 { |
| optsCopy.Intermediates = x509.NewCertPool() |
| for _, intermediate := range req.TLS.PeerCertificates[1:] { |
| optsCopy.Intermediates.AddCert(intermediate) |
| } |
| } |
| |
| if _, err := req.TLS.PeerCertificates[0].Verify(optsCopy); err != nil { |
| return nil, false, err |
| } |
| if err := a.verifySubject(req.TLS.PeerCertificates[0].Subject); err != nil { |
| return nil, false, err |
| } |
| return a.auth.AuthenticateRequest(req) |
| } |
| |
| func (a *Verifier) verifySubject(subject pkix.Name) error { |
| // No CN restrictions |
| if len(a.allowedCommonNames) == 0 { |
| return nil |
| } |
| // Enforce CN restrictions |
| if a.allowedCommonNames.Has(subject.CommonName) { |
| return nil |
| } |
| glog.Warningf("x509: subject with cn=%s is not in the allowed list: %v", subject.CommonName, a.allowedCommonNames.List()) |
| return fmt.Errorf("x509: subject with cn=%s is not allowed", subject.CommonName) |
| } |
| |
| // DefaultVerifyOptions returns VerifyOptions that use the system root certificates, current time, |
| // and requires certificates to be valid for client auth (x509.ExtKeyUsageClientAuth) |
| func DefaultVerifyOptions() x509.VerifyOptions { |
| return x509.VerifyOptions{ |
| KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth}, |
| } |
| } |
| |
| // CommonNameUserConversion builds user info from a certificate chain using the subject's CommonName |
| var CommonNameUserConversion = UserConversionFunc(func(chain []*x509.Certificate) (user.Info, bool, error) { |
| if len(chain[0].Subject.CommonName) == 0 { |
| return nil, false, nil |
| } |
| return &user.DefaultInfo{ |
| Name: chain[0].Subject.CommonName, |
| Groups: chain[0].Subject.Organization, |
| }, true, nil |
| }) |
| |
| // DNSNameUserConversion builds user info from a certificate chain using the first DNSName on the certificate |
| var DNSNameUserConversion = UserConversionFunc(func(chain []*x509.Certificate) (user.Info, bool, error) { |
| if len(chain[0].DNSNames) == 0 { |
| return nil, false, nil |
| } |
| return &user.DefaultInfo{Name: chain[0].DNSNames[0]}, true, nil |
| }) |
| |
| // EmailAddressUserConversion builds user info from a certificate chain using the first EmailAddress on the certificate |
| var EmailAddressUserConversion = UserConversionFunc(func(chain []*x509.Certificate) (user.Info, bool, error) { |
| var emailAddressOID asn1.ObjectIdentifier = []int{1, 2, 840, 113549, 1, 9, 1} |
| if len(chain[0].EmailAddresses) == 0 { |
| for _, name := range chain[0].Subject.Names { |
| if name.Type.Equal(emailAddressOID) { |
| return &user.DefaultInfo{Name: name.Value.(string)}, true, nil |
| } |
| } |
| return nil, false, nil |
| } |
| return &user.DefaultInfo{Name: chain[0].EmailAddresses[0]}, true, nil |
| }) |