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
|
package ssh
import (
"bytes"
"context"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/x509"
"encoding/pem"
"fmt"
"net"
"os"
"path/filepath"
"strconv"
"strings"
"testing"
"github.com/sirupsen/logrus"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
"golang.org/x/crypto/ssh"
)
func TestRunner(t *testing.T) {
dir := t.TempDir()
clientKey, err := ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
require.NoError(t, err)
clientKeyFile := filepath.Join(dir, "private.key")
writePrivateKey(t, clientKeyFile, clientKey)
cancel, runner, _ := createListenerAndSSHServer(t, clientKey, clientKeyFile)
assert.NoError(t, err)
defer runner.Close()
bin, _, err := runner.Run("echo hello")
assert.NoError(t, err)
assert.Equal(t, "hello", bin)
cancel()
// Expect error when sending data over close ssh server channel
assert.Error(t, runner.CopyDataPrivileged([]byte(`hello world`), "/hello", 0644))
_, runner, totalConn := createListenerAndSSHServer(t, clientKey, clientKeyFile)
assert.NoError(t, runner.CopyDataPrivileged([]byte(`hello world`), "/hello", 0644))
assert.NoError(t, runner.CopyDataPrivileged([]byte(`hello world`), "/hello", 0644))
assert.NoError(t, runner.CopyDataPrivileged([]byte(`hello world`), "/hello", 0644))
assert.NoError(t, runner.CopyData([]byte(`hello world`), "/home/core/hello", 0644))
assert.Equal(t, 1, *totalConn)
}
func createListenerAndSSHServer(t *testing.T, clientKey *ecdsa.PrivateKey, clientKeyFile string) (context.CancelFunc, *Runner, *int) {
listener, err := net.Listen("tcp", "127.0.0.1:")
require.NoError(t, err)
addr := listener.Addr().String()
runner, err := CreateRunner(ipFor(addr), portFor(addr), clientKeyFile)
require.NoError(t, err)
ctx, cancel := context.WithCancel(context.Background())
totalConn := createSSHServer(ctx, t, listener, clientKey, func(input string) (byte, string) {
escaped := fmt.Sprintf("%q", input)
if escaped == `"echo hello"` {
return 0, "hello"
}
if escaped == `"sudo install -m 0644 /dev/null /hello && cat <<EOF | base64 --decode | sudo tee /hello\naGVsbG8gd29ybGQ=\nEOF"` {
return 0, ""
}
if escaped == `"install -m 0644 /dev/null /home/core/hello && cat <<EOF | base64 --decode | tee /home/core/hello\naGVsbG8gd29ybGQ=\nEOF"` {
return 0, ""
}
return 1, fmt.Sprintf("unexpected command: %q", input)
})
return cancel, runner, totalConn
}
func createSSHServer(ctx context.Context, t *testing.T, listener net.Listener, clientKey *ecdsa.PrivateKey, fun func(string) (byte, string)) *int {
totalConn := 0
config := &ssh.ServerConfig{
PublicKeyCallback: func(c ssh.ConnMetadata, pubKey ssh.PublicKey) (*ssh.Permissions, error) {
pub, err := ssh.NewPublicKey(&clientKey.PublicKey)
if err != nil {
return nil, err
}
if bytes.Equal(pubKey.Marshal(), pub.Marshal()) && c.User() == "core" {
return &ssh.Permissions{
Extensions: map[string]string{
"pubkey-fp": ssh.FingerprintSHA256(pubKey),
},
}, nil
}
return nil, fmt.Errorf("unknown public key for %q", c.User())
},
}
serverKey, err := ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
require.NoError(t, err)
signer, err := ssh.NewSignerFromKey(serverKey)
require.NoError(t, err)
config.AddHostKey(signer)
go func() {
for {
nConn, err := listener.Accept()
if err != nil {
logrus.Debugf("cannot accept connection: %v", err)
return
}
totalConn++
conn, chans, reqs, err := ssh.NewServerConn(nConn, config)
require.NoError(t, err)
defer conn.Close()
logrus.Debugf("logged in with key %s\n", conn.Permissions.Extensions["pubkey-fp"])
go ssh.DiscardRequests(reqs)
for newChannel := range chans {
select {
case <-ctx.Done():
return
default:
if newChannel.ChannelType() != "session" {
_ = newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
continue
}
channel, requests, err := newChannel.Accept()
require.NoError(t, err)
go func(in <-chan *ssh.Request) {
for req := range in {
command := string(req.Payload[4 : req.Payload[3]+4])
logrus.Debugf("received command: %s", command)
_ = req.Reply(req.Type == "exec", nil)
ret, out := fun(command)
_, _ = channel.Write([]byte(out))
_, _ = channel.SendRequest("exit-status", false, []byte{0, 0, 0, ret})
_ = channel.Close()
}
}(requests)
}
}
}
}()
return &totalConn
}
func writePrivateKey(t *testing.T, clientKeyFile string, clientKey *ecdsa.PrivateKey) {
privateKeyFile, err := os.OpenFile(clientKeyFile, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
require.NoError(t, err)
defer privateKeyFile.Close()
bytes, _ := x509.MarshalPKCS8PrivateKey(clientKey)
require.NoError(t, pem.Encode(privateKeyFile, &pem.Block{
Type: "PRIVATE KEY",
Bytes: bytes,
}))
}
func ipFor(addr string) string {
return strings.Split(addr, ":")[0]
}
func portFor(addr string) int {
port, _ := strconv.Atoi(strings.Split(addr, ":")[1])
return port
}
func TestGenerateSSHKey(t *testing.T) {
tmpDir := t.TempDir()
filename := filepath.Join(tmpDir, "sshkey")
if err := GenerateSSHKey(filename); err != nil {
t.Fatal(err)
}
if _, err := os.Stat(filename); err != nil {
t.Fatalf("expected ssh key at %s", filename)
}
}
|
