-
Notifications
You must be signed in to change notification settings - Fork 64
/
x509SubjectAltNameUPN.go
175 lines (155 loc) · 4.87 KB
/
x509SubjectAltNameUPN.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
/*
* Copyright 2020 Venafi, Inc.
*
* 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 certificate
import (
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"fmt"
"log"
"net"
"net/url"
)
// userPrincipalName format for ASN.1
type userPrincipalName struct {
Name string `asn1:"utf8"`
}
// otherName SAN value format for ASN.1
type otherName struct {
OID asn1.ObjectIdentifier
Value userPrincipalName `asn1:"tag:0"`
}
var (
oidExtensionSubjectAltName = asn1.ObjectIdentifier{2, 5, 29, 17}
oidUserPrincipalName = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 20, 2, 3}
)
const (
nameTypeOther = 0
nameTypeEmail = 1
nameTypeDNS = 2
nameTypeURI = 6
nameTypeIP = 7
)
// Workaround for lack of User Principal Name SAN support in crypto/x509 package
func addUserPrincipalNameSANs(req *x509.CertificateRequest, upNames []string) {
sanBytes, err := marshalSANs(req.DNSNames, req.EmailAddresses, req.IPAddresses, req.URIs, upNames)
if err != nil {
log.Fatal(err)
}
extSubjectAltName := pkix.Extension{
Id: oidExtensionSubjectAltName,
Critical: false,
Value: sanBytes,
}
updatedExts := []pkix.Extension{extSubjectAltName}
// Preserve any other extra extensions, if any
for _, ext := range req.ExtraExtensions {
if !ext.Id.Equal(oidExtensionSubjectAltName) {
updatedExts = append(updatedExts, ext)
}
}
req.ExtraExtensions = updatedExts
// Clear the SAN request attributes to prevent the SAN extension from being clobbered when CSR is generated
req.DNSNames = nil
req.EmailAddresses = nil
req.IPAddresses = nil
req.URIs = nil
}
// Enhance crypto/x509 marshalSANs method to additionally support User Principal Name SANs
// Based on https://github.com/golang/go/blob/master/src/crypto/x509/x509.go#L1656-L1678
func marshalSANs(dnsNames, emailAddresses []string, ipAddresses []net.IP, uris []*url.URL, uPNames []string) (derBytes []byte, err error) {
var rawValues []asn1.RawValue
for _, name := range dnsNames {
rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeDNS, Class: 2, Bytes: []byte(name)})
}
for _, email := range emailAddresses {
rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeEmail, Class: 2, Bytes: []byte(email)})
}
for _, rawIP := range ipAddresses {
// If possible, we always want to encode IPv4 addresses in 4 bytes.
ip := rawIP.To4()
if ip == nil {
ip = rawIP
}
rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeIP, Class: 2, Bytes: ip})
}
for _, uri := range uris {
rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeURI, Class: 2, Bytes: []byte(uri.String())})
}
for _, upn := range uPNames {
var raw asn1.RawValue
name, _ := asn1.Marshal(otherName{
OID: oidUserPrincipalName,
Value: userPrincipalName{
Name: upn,
},
})
_, err = asn1.Unmarshal(name, &raw)
if err != nil {
return nil, fmt.Errorf("could not parse otherName SAN: %v", err)
}
rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeOther, Class: 2, IsCompound: true, Bytes: raw.Bytes})
}
return asn1.Marshal(rawValues)
}
// Since crypto/x509 package is not aware of UPN SANs, implement our own parsing method
func getUserPrincipalNameSANs(cert *x509.Certificate) (ret []string, err error) {
for _, ext := range cert.Extensions {
if !ext.Id.Equal(oidExtensionSubjectAltName) {
continue
}
var seq asn1.RawValue
rest, err := asn1.Unmarshal(ext.Value, &seq)
if err != nil {
return nil, err
} else if len(rest) != 0 {
return nil, fmt.Errorf("unexpected trailing data after X.509 extension")
}
if !seq.IsCompound || seq.Tag != 16 || seq.Class != 0 {
return nil, asn1.StructuralError{Msg: "bad ASN.1 sequence for SAN"}
}
rest = seq.Bytes
for len(rest) > 0 {
var v asn1.RawValue
rest, err = asn1.Unmarshal(rest, &v)
if err != nil {
return nil, err
}
upn, err := parseUserPrincipalNameSAN(v.Tag, v.FullBytes)
if err != nil {
return nil, err
}
if upn != "" {
ret = append(ret, upn)
}
}
}
return ret, nil
}
func parseUserPrincipalNameSAN(tag int, data []byte) (name string, err error) {
if tag != 0 {
return "", nil // SAN is not an otherName
}
var other otherName
_, err = asn1.UnmarshalWithParams(data, &other, "tag:0")
if err != nil {
return "", fmt.Errorf("could not parse otherName SAN: %v", err)
}
if other.OID.Equal(oidUserPrincipalName) {
return other.Value.Name, nil
}
return "", nil // otherName SAN is not a user principal name
}