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
|
package signer
import (
"crypto/rand"
"fmt"
"io/ioutil"
"time"
"github.com/nsheridan/cashier/lib"
"github.com/nsheridan/cashier/server/config"
"golang.org/x/crypto/ssh"
)
type KeySigner struct {
ca ssh.Signer
validity time.Duration
principals []string
permissions map[string]string
}
func (s *KeySigner) SignUserKey(req *lib.SignRequest) (string, error) {
pubkey, _, _, _, err := ssh.ParseAuthorizedKey([]byte(req.Key))
if err != nil {
return "", err
}
expires := time.Now().Add(s.validity)
if req.ValidUntil.After(expires) {
req.ValidUntil = expires
}
cert := &ssh.Certificate{
CertType: ssh.UserCert,
Key: pubkey,
KeyId: req.Principal,
ValidBefore: uint64(req.ValidUntil.Unix()),
ValidAfter: uint64(time.Now().Add(-5 * time.Minute).Unix()),
}
cert.ValidPrincipals = append(cert.ValidPrincipals, req.Principal)
cert.ValidPrincipals = append(cert.ValidPrincipals, s.principals...)
cert.Extensions = s.permissions
if err := cert.SignCert(rand.Reader, s.ca); err != nil {
return "", err
}
marshaled := ssh.MarshalAuthorizedKey(cert)
// Remove the trailing newline.
marshaled = marshaled[:len(marshaled)-1]
return string(marshaled), nil
}
func makeperms(perms []string) map[string]string {
if len(perms) > 0 {
m := make(map[string]string)
for _, p := range perms {
m[p] = ""
}
return m
}
return map[string]string{
"permit-X11-forwarding": "",
"permit-agent-forwarding": "",
"permit-port-forwarding": "",
"permit-pty": "",
"permit-user-rc": "",
}
}
func NewSigner(conf config.SSH) (*KeySigner, error) {
data, err := ioutil.ReadFile(conf.SigningKey)
if err != nil {
return nil, fmt.Errorf("unable to read CA key %s: %v", conf.SigningKey, err)
}
key, err := ssh.ParsePrivateKey(data)
if err != nil {
return nil, fmt.Errorf("unable to parse CA key: %v", err)
}
validity, err := time.ParseDuration(conf.MaxAge)
if err != nil {
return nil, fmt.Errorf("error parsing duration '%s': %v", conf.MaxAge, err)
}
return &KeySigner{
ca: key,
validity: validity,
principals: conf.Principals,
permissions: makeperms(conf.Permissions),
}, nil
}
|
