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Add metric for remaining lifetime of certificates authenticating requests #50387

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merged 1 commit into from
Aug 16, 2017
Merged

Add metric for remaining lifetime of certificates authenticating requests #50387

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1 change: 1 addition & 0 deletions staging/src/k8s.io/apiserver/pkg/authentication/request/x509/BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ go_library(
tags = ["automanaged"],
deps = [
"//vendor/github.com/golang/glog:go_default_library",
"//vendor/github.com/prometheus/client_golang/prometheus:go_default_library",
"//vendor/k8s.io/apimachinery/pkg/util/errors:go_default_library",
"//vendor/k8s.io/apimachinery/pkg/util/sets:go_default_library",
"//vendor/k8s.io/apiserver/pkg/authentication/authenticator:go_default_library",
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26 changes: 26 additions & 0 deletions staging/src/k8s.io/apiserver/pkg/authentication/request/x509/x509.go
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Original file line number Diff line number Diff line change
Expand Up @@ -22,15 +22,39 @@ import (
"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(),
},
},
)

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)
Expand Down Expand Up @@ -71,6 +95,8 @@ func (a *Authenticator) AuthenticateRequest(req *http.Request) (user.Info, bool,
}
}

remaining := req.TLS.PeerCertificates[0].NotAfter.Sub(time.Now())
clientCertificateExpirationHistogram.Observe(remaining.Seconds())
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@brancz brancz Sep 19, 2017 •
edited

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Wouldn't it make sense to measure this after verifying? If I understand this correctly a client could now influence these metrics by generating certificates with random expiry dates, not that I can see a particularly useful attack here, just a potential for distortion. It would be simple to just move this measurement after the certificate verification 4 lines below 🙂. Please let me know if I'm missing something.

chains, err := req.TLS.PeerCertificates[0].Verify(optsCopy)
if err != nil {
return nil, false, err
Expand Down