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
|
// Copyright 2022 The Sigstore 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 kubernetes
import (
"context"
"crypto/x509"
"net/url"
"github.com/coreos/go-oidc/v3/oidc"
"github.com/sigstore/fulcio/pkg/certificate"
"github.com/sigstore/fulcio/pkg/identity"
)
type principal struct {
// Subject ('sub') from ID token
subject string
// Issuer ('iss') from ID token
issuer string
// URI to be set in certificate. URI is of the form
// https://kubernetes.io/namespaces/<namespace>/serviceaccounts/<serviceaccount>.
uri string
}
func PrincipalFromIDToken(_ context.Context, token *oidc.IDToken) (identity.Principal, error) {
k8sURI, err := kubernetesToken(token)
if err != nil {
return nil, err
}
return principal{
subject: token.Subject,
issuer: token.Issuer,
uri: k8sURI,
}, nil
}
func (p principal) Name(context.Context) string {
return p.subject
}
func (p principal) Embed(_ context.Context, cert *x509.Certificate) error {
parsed, err := url.Parse(p.uri)
if err != nil {
return err
}
cert.URIs = []*url.URL{parsed}
cert.ExtraExtensions, err = certificate.Extensions{
Issuer: p.issuer,
}.Render()
if err != nil {
return err
}
return nil
}
func kubernetesToken(token *oidc.IDToken) (string, error) {
// Extract custom claims
var claims struct {
// "kubernetes.io": {
// "namespace": "default",
// "pod": {
// "name": "oidc-test",
// "uid": "49ad3572-b3dd-43a6-8d77-5858d3660275"
// },
// "serviceaccount": {
// "name": "default",
// "uid": "f5720c1d-e152-4356-a897-11b07aff165d"
// }
// }
Kubernetes struct {
Namespace string `json:"namespace"`
Pod struct {
Name string `json:"name"`
UID string `json:"uid"`
} `json:"pod"`
ServiceAccount struct {
Name string `json:"name"`
UID string `json:"uid"`
} `json:"serviceaccount"`
} `json:"kubernetes.io"`
}
if err := token.Claims(&claims); err != nil {
return "", err
}
// We use this in URIs, so it has to be a URI.
return "https://kubernetes.io/namespaces/" + claims.Kubernetes.Namespace + "/serviceaccounts/" + claims.Kubernetes.ServiceAccount.Name, nil
}
|
