forked from tailscale/tailscale
/
client.go
324 lines (297 loc) · 9.1 KB
/
client.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
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package kube provides a client to interact with Kubernetes.
// This package is Tailscale-internal and not meant for external consumption.
// Further, the API should not be considered stable.
package kube
import (
"bytes"
"context"
"crypto/tls"
"crypto/x509"
"encoding/json"
"fmt"
"io"
"log"
"net"
"net/http"
"net/url"
"os"
"path/filepath"
"sync"
"time"
"tailscale.com/util/multierr"
)
const (
saPath = "/var/run/secrets/kubernetes.io/serviceaccount"
defaultURL = "https://kubernetes.default.svc"
)
// rootPathForTests is set by tests to override the root path to the
// service account directory.
var rootPathForTests string
// SetRootPathForTesting sets the path to the service account directory.
func SetRootPathForTesting(p string) {
rootPathForTests = p
}
func readFile(n string) ([]byte, error) {
if rootPathForTests != "" {
return os.ReadFile(filepath.Join(rootPathForTests, saPath, n))
}
return os.ReadFile(filepath.Join(saPath, n))
}
// Client handles connections to Kubernetes.
// It expects to be run inside a cluster.
type Client struct {
mu sync.Mutex
url string
ns string
client *http.Client
token string
tokenExpiry time.Time
}
// New returns a new client
func New() (*Client, error) {
ns, err := readFile("namespace")
if err != nil {
return nil, err
}
caCert, err := readFile("ca.crt")
if err != nil {
return nil, err
}
cp := x509.NewCertPool()
if ok := cp.AppendCertsFromPEM(caCert); !ok {
return nil, fmt.Errorf("kube: error in creating root cert pool")
}
return &Client{
url: defaultURL,
ns: string(ns),
client: &http.Client{
Transport: &http.Transport{
TLSClientConfig: &tls.Config{
RootCAs: cp,
},
},
},
}, nil
}
// SetURL sets the URL to use for the Kubernetes API.
// This is used only for testing.
func (c *Client) SetURL(url string) {
c.url = url
}
// SetDialer sets the dialer to use when establishing a connection
// to the Kubernetes API server.
func (c *Client) SetDialer(dialer func(ctx context.Context, network, addr string) (net.Conn, error)) {
c.client.Transport.(*http.Transport).DialContext = dialer
}
func (c *Client) expireToken() {
c.mu.Lock()
defer c.mu.Unlock()
c.tokenExpiry = time.Now()
}
func (c *Client) getOrRenewToken() (string, error) {
c.mu.Lock()
defer c.mu.Unlock()
tk, te := c.token, c.tokenExpiry
if time.Now().Before(te) {
return tk, nil
}
tkb, err := readFile("token")
if err != nil {
return "", err
}
c.token = string(tkb)
c.tokenExpiry = time.Now().Add(30 * time.Minute)
return c.token, nil
}
func (c *Client) secretURL(name string) string {
if name == "" {
return fmt.Sprintf("%s/api/v1/namespaces/%s/secrets", c.url, c.ns)
}
return fmt.Sprintf("%s/api/v1/namespaces/%s/secrets/%s", c.url, c.ns, name)
}
func getError(resp *http.Response) error {
if resp.StatusCode == 200 || resp.StatusCode == 201 {
// These are the only success codes returned by the Kubernetes API.
// https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md#http-status-codes
return nil
}
st := &Status{}
if err := json.NewDecoder(resp.Body).Decode(st); err != nil {
return err
}
return st
}
func setHeader(key, value string) func(*http.Request) {
return func(req *http.Request) {
req.Header.Set(key, value)
}
}
// doRequest performs an HTTP request to the Kubernetes API.
// If in is not nil, it is expected to be a JSON-encodable object and will be
// sent as the request body.
// If out is not nil, it is expected to be a pointer to an object that can be
// decoded from JSON.
// If the request fails with a 401, the token is expired and a new one is
// requested.
func (c *Client) doRequest(ctx context.Context, method, url string, in, out any, opts ...func(*http.Request)) error {
req, err := c.newRequest(ctx, method, url, in)
if err != nil {
return err
}
for _, opt := range opts {
opt(req)
}
resp, err := c.client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
if err := getError(resp); err != nil {
if st, ok := err.(*Status); ok && st.Code == 401 {
c.expireToken()
}
return err
}
if out != nil {
return json.NewDecoder(resp.Body).Decode(out)
}
return nil
}
func (c *Client) newRequest(ctx context.Context, method, url string, in any) (*http.Request, error) {
tk, err := c.getOrRenewToken()
if err != nil {
return nil, err
}
var body io.Reader
if in != nil {
switch in := in.(type) {
case []byte:
body = bytes.NewReader(in)
default:
var b bytes.Buffer
if err := json.NewEncoder(&b).Encode(in); err != nil {
return nil, err
}
body = &b
}
}
req, err := http.NewRequestWithContext(ctx, method, url, body)
if err != nil {
return nil, err
}
if body != nil {
req.Header.Add("Content-Type", "application/json")
}
req.Header.Add("Accept", "application/json")
req.Header.Add("Authorization", "Bearer "+tk)
return req, nil
}
// GetSecret fetches the secret from the Kubernetes API.
func (c *Client) GetSecret(ctx context.Context, name string) (*Secret, error) {
s := &Secret{Data: make(map[string][]byte)}
if err := c.doRequest(ctx, "GET", c.secretURL(name), nil, s); err != nil {
return nil, err
}
return s, nil
}
// CreateSecret creates a secret in the Kubernetes API.
func (c *Client) CreateSecret(ctx context.Context, s *Secret) error {
s.Namespace = c.ns
return c.doRequest(ctx, "POST", c.secretURL(""), s, nil)
}
// UpdateSecret updates a secret in the Kubernetes API.
func (c *Client) UpdateSecret(ctx context.Context, s *Secret) error {
return c.doRequest(ctx, "PUT", c.secretURL(s.Name), s, nil)
}
// JSONPatch is a JSON patch operation.
// It currently (2023-03-02) only supports the "remove" operation.
//
// https://tools.ietf.org/html/rfc6902
type JSONPatch struct {
Op string `json:"op"`
Path string `json:"path"`
Value any `json:"value,omitempty"`
}
// JSONPatchSecret updates a secret in the Kubernetes API using a JSON patch.
// It currently (2023-03-02) only supports the "remove" operation.
func (c *Client) JSONPatchSecret(ctx context.Context, name string, patch []JSONPatch) error {
for _, p := range patch {
if p.Op != "remove" && p.Op != "add" {
panic(fmt.Errorf("unsupported JSON patch operation: %q", p.Op))
}
}
return c.doRequest(ctx, "PATCH", c.secretURL(name), patch, nil, setHeader("Content-Type", "application/json-patch+json"))
}
// StrategicMergePatchSecret updates a secret in the Kubernetes API using a
// strategic merge patch.
// If a fieldManager is provided, it will be used to track the patch.
func (c *Client) StrategicMergePatchSecret(ctx context.Context, name string, s *Secret, fieldManager string) error {
surl := c.secretURL(name)
if fieldManager != "" {
uv := url.Values{
"fieldManager": {fieldManager},
}
surl += "?" + uv.Encode()
}
s.Namespace = c.ns
s.Name = name
return c.doRequest(ctx, "PATCH", surl, s, nil, setHeader("Content-Type", "application/strategic-merge-patch+json"))
}
// CheckSecretPermissions checks the secret access permissions of the current
// pod. It returns an error if the basic permissions tailscale needs are
// missing, and reports whether the patch permission is additionally present.
//
// Errors encountered during the access checking process are logged, but ignored
// so that the pod tries to fail alive if the permissions exist and there's just
// something wrong with SelfSubjectAccessReviews. There shouldn't be, pods
// should always be able to use SSARs to assess their own permissions, but since
// we didn't use to check permissions this way we'll be cautious in case some
// old version of k8s deviates from the current behavior.
func (c *Client) CheckSecretPermissions(ctx context.Context, secretName string) (canPatch bool, err error) {
var errs []error
for _, verb := range []string{"get", "update"} {
ok, err := c.checkPermission(ctx, verb, secretName)
if err != nil {
log.Printf("error checking %s permission on secret %s: %v", verb, secretName, err)
} else if !ok {
errs = append(errs, fmt.Errorf("missing %s permission on secret %q", verb, secretName))
}
}
if len(errs) > 0 {
return false, multierr.New(errs...)
}
ok, err := c.checkPermission(ctx, "patch", secretName)
if err != nil {
log.Printf("error checking patch permission on secret %s: %v", secretName, err)
return false, nil
}
return ok, nil
}
// checkPermission reports whether the current pod has permission to use the
// given verb (e.g. get, update, patch) on secretName.
func (c *Client) checkPermission(ctx context.Context, verb, secretName string) (bool, error) {
sar := map[string]any{
"apiVersion": "authorization.k8s.io/v1",
"kind": "SelfSubjectAccessReview",
"spec": map[string]any{
"resourceAttributes": map[string]any{
"namespace": c.ns,
"verb": verb,
"resource": "secrets",
"name": secretName,
},
},
}
var res struct {
Status struct {
Allowed bool `json:"allowed"`
} `json:"status"`
}
url := c.url + "/apis/authorization.k8s.io/v1/selfsubjectaccessreviews"
if err := c.doRequest(ctx, "POST", url, sar, &res); err != nil {
return false, err
}
return res.Status.Allowed, nil
}