forked from kubernetes/kubernetes
-
Notifications
You must be signed in to change notification settings - Fork 0
/
claims.go
226 lines (195 loc) · 8.35 KB
/
claims.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
/*
Copyright 2018 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 serviceaccount
import (
"context"
"errors"
"fmt"
"time"
"github.com/go-jose/go-jose/v3/jwt"
"k8s.io/apiserver/pkg/audit"
"k8s.io/klog/v2"
apiserverserviceaccount "k8s.io/apiserver/pkg/authentication/serviceaccount"
"k8s.io/kubernetes/pkg/apis/core"
)
const (
// Injected bound service account token expiration which triggers monitoring of its time-bound feature.
WarnOnlyBoundTokenExpirationSeconds = 60*60 + 7
// Extended expiration for those modified tokens involved in safe rollout if time-bound feature.
ExpirationExtensionSeconds = 24 * 365 * 60 * 60
)
// time.Now stubbed out to allow testing
var now = time.Now
type privateClaims struct {
Kubernetes kubernetes `json:"kubernetes.io,omitempty"`
}
type kubernetes struct {
Namespace string `json:"namespace,omitempty"`
Svcacct ref `json:"serviceaccount,omitempty"`
Pod *ref `json:"pod,omitempty"`
Secret *ref `json:"secret,omitempty"`
WarnAfter *jwt.NumericDate `json:"warnafter,omitempty"`
}
type ref struct {
Name string `json:"name,omitempty"`
UID string `json:"uid,omitempty"`
}
func Claims(sa core.ServiceAccount, pod *core.Pod, secret *core.Secret, expirationSeconds, warnafter int64, audience []string) (*jwt.Claims, interface{}) {
now := now()
sc := &jwt.Claims{
Subject: apiserverserviceaccount.MakeUsername(sa.Namespace, sa.Name),
Audience: jwt.Audience(audience),
IssuedAt: jwt.NewNumericDate(now),
NotBefore: jwt.NewNumericDate(now),
Expiry: jwt.NewNumericDate(now.Add(time.Duration(expirationSeconds) * time.Second)),
}
pc := &privateClaims{
Kubernetes: kubernetes{
Namespace: sa.Namespace,
Svcacct: ref{
Name: sa.Name,
UID: string(sa.UID),
},
},
}
switch {
case pod != nil:
pc.Kubernetes.Pod = &ref{
Name: pod.Name,
UID: string(pod.UID),
}
case secret != nil:
pc.Kubernetes.Secret = &ref{
Name: secret.Name,
UID: string(secret.UID),
}
}
if warnafter != 0 {
pc.Kubernetes.WarnAfter = jwt.NewNumericDate(now.Add(time.Duration(warnafter) * time.Second))
}
return sc, pc
}
func NewValidator(getter ServiceAccountTokenGetter) Validator {
return &validator{
getter: getter,
}
}
type validator struct {
getter ServiceAccountTokenGetter
}
var _ = Validator(&validator{})
func (v *validator) Validate(ctx context.Context, _ string, public *jwt.Claims, privateObj interface{}) (*apiserverserviceaccount.ServiceAccountInfo, error) {
private, ok := privateObj.(*privateClaims)
if !ok {
klog.Errorf("service account jwt validator expected private claim of type *privateClaims but got: %T", privateObj)
return nil, errors.New("service account token claims could not be validated due to unexpected private claim")
}
nowTime := now()
err := public.Validate(jwt.Expected{
Time: nowTime,
})
switch err {
case nil:
// successful validation
case jwt.ErrExpired:
return nil, errors.New("service account token has expired")
case jwt.ErrNotValidYet:
return nil, errors.New("service account token is not valid yet")
case jwt.ErrIssuedInTheFuture:
return nil, errors.New("service account token is issued in the future")
// our current use of jwt.Expected above should make these cases impossible to hit
case jwt.ErrInvalidAudience, jwt.ErrInvalidID, jwt.ErrInvalidIssuer, jwt.ErrInvalidSubject:
klog.Errorf("service account token claim validation got unexpected validation failure: %v", err)
return nil, fmt.Errorf("service account token claims could not be validated: %w", err) // safe to pass these errors back to the user
default:
klog.Errorf("service account token claim validation got unexpected error type: %T", err) // avoid leaking unexpected information into the logs
return nil, errors.New("service account token claims could not be validated due to unexpected validation error") // return an opaque error
}
// consider things deleted prior to now()-leeway to be invalid
invalidIfDeletedBefore := nowTime.Add(-jwt.DefaultLeeway)
namespace := private.Kubernetes.Namespace
saref := private.Kubernetes.Svcacct
podref := private.Kubernetes.Pod
secref := private.Kubernetes.Secret
// Make sure service account still exists (name and UID)
serviceAccount, err := v.getter.GetServiceAccount(namespace, saref.Name)
if err != nil {
klog.V(4).Infof("Could not retrieve service account %s/%s: %v", namespace, saref.Name, err)
return nil, err
}
if serviceAccount.DeletionTimestamp != nil && serviceAccount.DeletionTimestamp.Time.Before(invalidIfDeletedBefore) {
klog.V(4).Infof("Service account has been deleted %s/%s", namespace, saref.Name)
return nil, fmt.Errorf("service account %s/%s has been deleted", namespace, saref.Name)
}
if string(serviceAccount.UID) != saref.UID {
klog.V(4).Infof("Service account UID no longer matches %s/%s: %q != %q", namespace, saref.Name, string(serviceAccount.UID), saref.UID)
return nil, fmt.Errorf("service account UID (%s) does not match claim (%s)", serviceAccount.UID, saref.UID)
}
if secref != nil {
// Make sure token hasn't been invalidated by deletion of the secret
secret, err := v.getter.GetSecret(namespace, secref.Name)
if err != nil {
klog.V(4).Infof("Could not retrieve bound secret %s/%s for service account %s/%s: %v", namespace, secref.Name, namespace, saref.Name, err)
return nil, errors.New("service account token has been invalidated")
}
if secret.DeletionTimestamp != nil && secret.DeletionTimestamp.Time.Before(invalidIfDeletedBefore) {
klog.V(4).Infof("Bound secret is deleted and awaiting removal: %s/%s for service account %s/%s", namespace, secref.Name, namespace, saref.Name)
return nil, errors.New("service account token has been invalidated")
}
if secref.UID != string(secret.UID) {
klog.V(4).Infof("Secret UID no longer matches %s/%s: %q != %q", namespace, secref.Name, string(secret.UID), secref.UID)
return nil, fmt.Errorf("secret UID (%s) does not match service account secret ref claim (%s)", secret.UID, secref.UID)
}
}
var podName, podUID string
if podref != nil {
// Make sure token hasn't been invalidated by deletion of the pod
pod, err := v.getter.GetPod(namespace, podref.Name)
if err != nil {
klog.V(4).Infof("Could not retrieve bound pod %s/%s for service account %s/%s: %v", namespace, podref.Name, namespace, saref.Name, err)
return nil, errors.New("service account token has been invalidated")
}
if pod.DeletionTimestamp != nil && pod.DeletionTimestamp.Time.Before(invalidIfDeletedBefore) {
klog.V(4).Infof("Bound pod is deleted and awaiting removal: %s/%s for service account %s/%s", namespace, podref.Name, namespace, saref.Name)
return nil, errors.New("service account token has been invalidated")
}
if podref.UID != string(pod.UID) {
klog.V(4).Infof("Pod UID no longer matches %s/%s: %q != %q", namespace, podref.Name, string(pod.UID), podref.UID)
return nil, fmt.Errorf("pod UID (%s) does not match service account pod ref claim (%s)", pod.UID, podref.UID)
}
podName = podref.Name
podUID = podref.UID
}
// Check special 'warnafter' field for projected service account token transition.
warnafter := private.Kubernetes.WarnAfter
if warnafter != nil && *warnafter != 0 {
if nowTime.After(warnafter.Time()) {
secondsAfterWarn := nowTime.Unix() - warnafter.Time().Unix()
auditInfo := fmt.Sprintf("subject: %s, seconds after warning threshold: %d", public.Subject, secondsAfterWarn)
audit.AddAuditAnnotation(ctx, "authentication.k8s.io/stale-token", auditInfo)
staleTokensTotal.WithContext(ctx).Inc()
} else {
validTokensTotal.WithContext(ctx).Inc()
}
}
return &apiserverserviceaccount.ServiceAccountInfo{
Namespace: private.Kubernetes.Namespace,
Name: private.Kubernetes.Svcacct.Name,
UID: private.Kubernetes.Svcacct.UID,
PodName: podName,
PodUID: podUID,
}, nil
}
func (v *validator) NewPrivateClaims() interface{} {
return &privateClaims{}
}