-
Notifications
You must be signed in to change notification settings - Fork 0
/
google.go
320 lines (283 loc) · 10.9 KB
/
google.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
// Copyright 2017 The LUCI 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 cloud
import (
"encoding/base64"
"encoding/json"
"fmt"
"io"
"net/http"
"sort"
"strings"
"time"
infoS "go.chromium.org/luci/gae/service/info"
"go.chromium.org/luci/common/clock"
"go.chromium.org/luci/common/data/caching/lru"
"go.chromium.org/luci/common/data/rand/mathrand"
"go.chromium.org/luci/common/errors"
"go.chromium.org/luci/common/retry/transient"
iamAPI "google.golang.org/api/iam/v1"
"golang.org/x/net/context"
"golang.org/x/oauth2"
"golang.org/x/oauth2/google"
)
// googleTokenSourceKey is a normalized string of service accounts, used as
// a key for oauth2.TokenSource instances in the token source cache.
//
// See TokenSource for more information.
type googleTokenSourceKey string
const (
// accessTokenMinExpiration is the minimum expiration time for an access
// token. We prematurely expire the token by this amount to ensure that it is
// useful once immediately fetched.
accessTokenMinExpiration = 2 * time.Minute
// accessTokenExpirationRandomization is a range before an access token
// expires where we randomly select a token user to refresh the token. This
// avoids cache stampede on token expiration where the entire service shuts
// down blocked on token refresh.
accessTokenExpirationRandomization = 3 * time.Minute
// publicCertificatesCacheExpiration is the expiration period for cached
// service account public certificates.
publicCertificatesCacheExpiration = 1 * time.Hour
// defaultGoogleServicesCacheSize is the default maximum number of elements
// that the LRU cache will hold.
defaultGoogleServicesCacheSize = 1024
)
var (
infoPublicCertificatesKey = "cloud.Info Public Certificates"
)
// GoogleServiceProvider is a ServiceProvider implementation that uses Google
// services.
type GoogleServiceProvider struct {
// ServiceAccount is the name of the system's service account.
ServiceAccount string
// Cache is the LRU cache to use to store values that are fetched from remote
// services.
Cache *lru.Cache
}
// PublicCertificates implements ServiceProvider's PublicCertificates using
// Google's public certificate endpoint.
func (gsp *GoogleServiceProvider) PublicCertificates(c context.Context) (certs []infoS.Certificate, err error) {
// Lock around our certificates. If they are already resolved, then we can
// quickly return them; otherwise, we will need to load them. This lock
// prevents concurrent certificate accesses from resulting in multiple
// remote resource requests.
v, err := gsp.Cache.GetOrCreate(c, &infoPublicCertificatesKey, func() (interface{}, time.Duration, error) {
// Request a certificate map from the Google x509 public certificte endpoint.
//
// Upon success, the result will be a map of key to PEM-encoded value.
url := fmt.Sprintf("https://www.googleapis.com/robot/v1/metadata/x509/%s", gsp.ServiceAccount)
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return nil, 0, errors.Annotate(err, "could not create HTTP request").Err()
}
req = req.WithContext(c)
resp, err := http.DefaultClient.Do(req)
if err != nil {
return nil, 0, errors.Annotate(err, "could not send request to %s", url).Tag(transient.Tag).Err()
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return nil, 0, errors.Annotate(err, "received HTTP %d from %s", resp.StatusCode, url).Tag(transient.Tag).Err()
}
var certMap map[string]string
etr := errTrackingReader{resp.Body, nil}
if err := json.NewDecoder(&etr).Decode(&certMap); err != nil {
if etr.err != nil {
// I/O error, mark as transient.
return nil, 0, errors.Annotate(err, "could not read HTTP response body").Tag(transient.Tag).Err()
}
return nil, 0, errors.Annotate(err, "could not decode HTTP response body").Err()
}
// Populate our certificate array and sort by key for determinism.
certs := make([]infoS.Certificate, 0, len(certMap))
for key, data := range certMap {
certs = append(certs, infoS.Certificate{
KeyName: key,
Data: []byte(data),
})
}
sort.Slice(certs, func(i, j int) bool { return certs[i].KeyName < certs[j].KeyName })
return certs, 0, nil
})
if err != nil {
return nil, err
}
return v.([]infoS.Certificate), nil
}
// TokenSource implements ServiceProvider's TokenSource API using the default
// Google token source.
//
// The way TokenSource is implemented, the service is vulnerable to a "cache
// stampede" effect where multiple access tokens invalidate at the same time and
// need to be refreshed.
//
// TokenSource instances for a set of scopes are cached so that their access
// tokens will similarly be cached.
func (gsp *GoogleServiceProvider) TokenSource(c context.Context, scopes ...string) (oauth2.TokenSource, error) {
cbts := contextBoundTokenSource{
Context: c,
cache: gsp.Cache,
cacheKey: accessTokenKeyForScopes(scopes),
makeTokenSource: func(c context.Context) (oauth2.TokenSource, error) {
return google.DefaultTokenSource(c, scopes...)
},
}
return &cbts, nil
}
// SignBytes implements ServiceProvider's SignBytes using Google Cloud IAM's
// "SignBlob" endpoint.
//
// The SignBlob RPC request that the GAE/Flex service account account is granted
// the "iam.serviceAccountActor" role, which is NOT default.
//
// https://cloud.google.com/iam/reference/rest/v1/projects.serviceAccounts/signBlob
func (gsp *GoogleServiceProvider) SignBytes(c context.Context, bytes []byte) (keyName string, signature []byte, err error) {
// Generate a client to use for the SignBytes API call.
var ts oauth2.TokenSource
if ts, err = gsp.TokenSource(c, iamAPI.CloudPlatformScope); err != nil {
return
}
client := oauth2.NewClient(c, ts)
// Construct an IAM service.
var svc *iamAPI.Service
if svc, err = iamAPI.New(client); err != nil {
err = errors.Annotate(err, "could not get IAM client").Err()
return
}
var resp *iamAPI.SignBlobResponse
req := svc.Projects.ServiceAccounts.SignBlob(
fmt.Sprintf("projects/-/serviceAccounts/%s", gsp.ServiceAccount),
&iamAPI.SignBlobRequest{
BytesToSign: base64.StdEncoding.EncodeToString(bytes),
})
resp, err = req.Context(c).Do()
if err != nil {
err = errors.Annotate(err, "SignBlob RPC failed").Err()
return
}
keyName = resp.KeyId
signature = []byte(resp.Signature)
return
}
// errTrackingReader wraps an io.Reader and retains an error, if the Reader
// returns an error.
//
// We use this becuase we chain an HTTP response's body Reader with a JSON
// unmarshaller, and want to be able to distinguish between an I/O error and a
// JSON unmarshalling error.
type errTrackingReader struct {
r io.Reader
err error
}
func (etr *errTrackingReader) Read(v []byte) (int, error) {
cnt, err := etr.r.Read(v)
if err != nil {
etr.err = err
}
return cnt, err
}
// accessTokenKey is a cache key used to store a minted access token.
//
// An access token is bound to a set of OAuth2 scopes, so it is keyed by a
// normalization of those scopes.
type accessTokenKey string
// contextBoundTokenSource is an oauth2.TokenSource bound to a specific Context.
//
// If an appropriate access token has already been generated and cached, it will
// be immediately reused. Otherwise, a new token will be minted under lock using
// the bound Context. If that minting succeeds, the token will be cached for
// other contextBoundTokenSource to use.
type contextBoundTokenSource struct {
context.Context
// cache is the LRU cache to use for caching access tokens.
cache *lru.Cache
// cacheKey is the cache key to use for the minted access token.
cacheKey accessTokenKey
// makeTokenSource creates a new oauth2.TokenSource bound to the supplied
// Context. This will be called to generate new access tokens as needed.
//
// oauth2.TokenSource will be obtained without any locking, but individual
// token generation will occur under lock.
makeTokenSource func(context.Context) (oauth2.TokenSource, error)
}
// Token generates a new OAuth2 token. It is part of the oauth2.TokenSource
// implementation.
func (c *contextBoundTokenSource) Token() (*oauth2.Token, error) {
now := clock.Now(c)
// Get the current token value. We do this without locking around the token
// element.
if tokIface, ok := c.cache.Get(c, c.cacheKey); ok {
tok := tokIface.(*oauth2.Token)
if !c.closeToExpRandomized(now, tok.Expiry, accessTokenExpirationRandomization) {
return tok, nil
}
}
// Either the token is expired, or we are selected randomly as a refresh case.
// Get a new TokenSource to refresh the token with.
ts, err := c.makeTokenSource(c)
if err != nil {
return nil, errors.Annotate(err, "failed to create new TokenSource").Err()
}
// While refreshing, we lock around the cache key via GetOrCreate in case
// multiple requests are either selected or have expired.
tokIface, err := c.cache.GetOrCreate(c, c.cacheKey, func() (interface{}, time.Duration, error) {
tok, err := ts.Token()
if err != nil {
return nil, 0, err
}
expiryDelta := tok.Expiry.Sub(now)
switch {
case expiryDelta <= 0:
return nil, 0, errors.Reason("retrieved expired access token (%s < %s)", tok.Expiry, now).Err()
case expiryDelta > accessTokenMinExpiration:
// Subtract some time from the token's expiry so we don't use it immediately
// before it actually expires.
tok.Expiry = tok.Expiry.Add(-accessTokenMinExpiration)
expiryDelta -= accessTokenMinExpiration
}
return tok, expiryDelta, nil
})
if err != nil {
return nil, errors.Annotate(err, "failed to mint new access token").Err()
}
return tokIface.(*oauth2.Token), nil
}
func (c *contextBoundTokenSource) closeToExpRandomized(now, exp time.Time, expRandomization time.Duration) bool {
switch {
case now.After(exp):
return true // expired already
case now.Add(expRandomization).Before(exp):
return false // far from expiration
default:
// The expiration is close enough. Do the randomization.
rnd := time.Duration(mathrand.Int63n(c, int64(expRandomization)))
return now.Add(rnd).After(exp)
}
}
func accessTokenKeyForScopes(scopes []string) accessTokenKey {
// Normalize "scopes", removing duplicates and sorting them. This will create
// an optimal deterministic key for a given set of scopes, regardless of their
// order.
scopesMap := make(map[string]struct{}, len(scopes))
for _, scope := range scopes {
scopesMap[scope] = struct{}{}
}
scopes = make([]string, 0, len(scopesMap))
for scope := range scopesMap {
scopes = append(scopes, scope)
}
sort.Strings(scopes)
return accessTokenKey(strings.Join(scopes, "\x00"))
}