forked from sigstore/sigstore
/
client.go
421 lines (375 loc) · 14 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
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
//
// Copyright 2021 The Sigstore 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 gcp implement the interface with google cloud kms service
package gcp
import (
"context"
"crypto"
"crypto/ecdsa"
"crypto/rsa"
"errors"
"fmt"
"github.com/gobars/sigstore/pkg/signature/myhash"
"hash/crc32"
"io"
"log"
"regexp"
"time"
gcpkms "cloud.google.com/go/kms/apiv1"
"cloud.google.com/go/kms/apiv1/kmspb"
"google.golang.org/api/option"
"google.golang.org/protobuf/types/known/wrapperspb"
"github.com/gobars/sigstore/pkg/cryptoutils"
"github.com/gobars/sigstore/pkg/signature"
sigkms "github.com/gobars/sigstore/pkg/signature/kms"
"github.com/gobars/sigstore/pkg/signature/options"
"github.com/jellydator/ttlcache/v3"
)
func init() {
sigkms.AddProvider(ReferenceScheme, func(ctx context.Context, keyResourceID string, _ myhash.Hash, opts ...signature.RPCOption) (sigkms.SignerVerifier, error) {
return LoadSignerVerifier(ctx, keyResourceID)
})
}
//nolint:revive
const (
AlgorithmECDSAP256SHA256 = "ecdsa-p256-sha256"
AlgorithmECDSAP384SHA384 = "ecdsa-p384-sha384"
AlgorithmRSAPKCS1v152048SHA256 = "rsa-pkcs1v15-2048-sha256"
AlgorithmRSAPKCS1v153072SHA256 = "rsa-pkcs1v15-3072-sha256"
AlgorithmRSAPKCS1v154096SHA256 = "rsa-pkcs1v15-4096-sha256"
AlgorithmRSAPKCS1v154096SHA512 = "rsa-pkcs1v15-4096-sha512"
AlgorithmRSAPSS2048SHA256 = "rsa-pss-2048-sha256"
AlgorithmRSAPSS3072SHA256 = "rsa-pss-3072-sha256"
AlgorithmRSAPSS4096SHA256 = "rsa-pss-4096-sha256"
AlgorithmRSAPSS4096SHA512 = "rsa-pss-4096-sha512"
)
var algorithmMap = map[string]kmspb.CryptoKeyVersion_CryptoKeyVersionAlgorithm{
AlgorithmECDSAP256SHA256: kmspb.CryptoKeyVersion_EC_SIGN_P256_SHA256,
AlgorithmECDSAP384SHA384: kmspb.CryptoKeyVersion_EC_SIGN_P384_SHA384,
AlgorithmRSAPKCS1v152048SHA256: kmspb.CryptoKeyVersion_RSA_SIGN_PKCS1_2048_SHA256,
AlgorithmRSAPKCS1v153072SHA256: kmspb.CryptoKeyVersion_RSA_SIGN_PKCS1_3072_SHA256,
AlgorithmRSAPKCS1v154096SHA256: kmspb.CryptoKeyVersion_RSA_SIGN_PKCS1_4096_SHA256,
AlgorithmRSAPKCS1v154096SHA512: kmspb.CryptoKeyVersion_RSA_SIGN_PKCS1_4096_SHA512,
AlgorithmRSAPSS2048SHA256: kmspb.CryptoKeyVersion_RSA_SIGN_PSS_2048_SHA256,
AlgorithmRSAPSS3072SHA256: kmspb.CryptoKeyVersion_RSA_SIGN_PSS_3072_SHA256,
AlgorithmRSAPSS4096SHA256: kmspb.CryptoKeyVersion_RSA_SIGN_PSS_4096_SHA256,
AlgorithmRSAPSS4096SHA512: kmspb.CryptoKeyVersion_RSA_SIGN_PSS_4096_SHA512,
}
type gcpClient struct {
defaultCtx context.Context
refString string
projectID string
locationID string
keyRing string
keyName string
version string
kvCache *ttlcache.Cache[string, cryptoKeyVersion]
kmsClient *gcpkms.KeyManagementClient
}
func newGCPClient(ctx context.Context, refStr string, opts ...option.ClientOption) (*gcpClient, error) {
if err := ValidReference(refStr); err != nil {
return nil, err
}
if ctx == nil {
ctx = context.Background()
}
g := &gcpClient{
defaultCtx: ctx,
refString: refStr,
kvCache: nil,
}
var err error
g.projectID, g.locationID, g.keyRing, g.keyName, g.version, err = parseReference(refStr)
if err != nil {
return nil, err
}
g.kmsClient, err = gcpkms.NewKeyManagementClient(ctx, opts...)
if err != nil {
return nil, fmt.Errorf("new gcp kms client: %w", err)
}
g.kvCache = ttlcache.New[string, cryptoKeyVersion](
ttlcache.WithDisableTouchOnHit[string, cryptoKeyVersion](),
)
// prime the cache
g.kvCache.Get(cacheKey)
return g, nil
}
var (
errKMSReference = errors.New("kms specification should be in the format gcpkms://projects/[PROJECT_ID]/locations/[LOCATION]/keyRings/[KEY_RING]/cryptoKeys/[KEY]/cryptoKeyVersions/[VERSION]")
re = regexp.MustCompile(`^gcpkms://projects/([^/]+)/locations/([^/]+)/keyRings/([^/]+)/cryptoKeys/([^/]+)(?:/(?:cryptoKeyVersions|versions)/([^/]+))?$`)
)
// ReferenceScheme schemes for various KMS services are copied from https://github.com/google/go-cloud/tree/master/secrets
const ReferenceScheme = "gcpkms://"
// ValidReference returns a non-nil error if the reference string is invalid
func ValidReference(ref string) error {
if !re.MatchString(ref) {
return errKMSReference
}
return nil
}
func parseReference(resourceID string) (projectID, locationID, keyRing, keyName, version string, err error) {
v := re.FindStringSubmatch(resourceID)
if len(v) != 6 {
err = fmt.Errorf("invalid gcpkms format %q", resourceID)
return
}
projectID, locationID, keyRing, keyName, version = v[1], v[2], v[3], v[4], v[5]
return
}
type cryptoKeyVersion struct {
CryptoKeyVersion *kmspb.CryptoKeyVersion
Verifier signature.Verifier
HashFunc myhash.Hash
}
// use a consistent key for cache lookups
const cacheKey = "crypto_key_version"
// keyVersionName returns the first key version found for a key in KMS
func (g *gcpClient) keyVersionName(ctx context.Context) (*cryptoKeyVersion, error) {
parent := fmt.Sprintf("projects/%s/locations/%s/keyRings/%s/cryptoKeys/%s", g.projectID, g.locationID, g.keyRing, g.keyName)
parentReq := &kmspb.GetCryptoKeyRequest{
Name: parent,
}
key, err := g.kmsClient.GetCryptoKey(ctx, parentReq)
if err != nil {
return nil, err
}
if key.Purpose != kmspb.CryptoKey_ASYMMETRIC_SIGN {
return nil, errors.New("specified key cannot be used to sign")
}
// if g.version was specified, use it explicitly
var kv *kmspb.CryptoKeyVersion
if g.version != "" {
req := &kmspb.GetCryptoKeyVersionRequest{
Name: parent + fmt.Sprintf("/cryptoKeyVersions/%s", g.version),
}
kv, err = g.kmsClient.GetCryptoKeyVersion(ctx, req)
if err != nil {
return nil, err
}
} else {
req := &kmspb.ListCryptoKeyVersionsRequest{
Parent: parent,
Filter: "state=ENABLED",
OrderBy: "name desc",
}
iterator := g.kmsClient.ListCryptoKeyVersions(ctx, req)
// pick the key version that is enabled with the greatest version value
kv, err = iterator.Next()
if err != nil {
return nil, fmt.Errorf("unable to find an enabled key version in GCP KMS: %w", err)
}
}
// kv is keyVersion to use
crv := cryptoKeyVersion{
CryptoKeyVersion: kv,
}
pubKey, err := g.fetchPublicKey(ctx, kv.Name)
if err != nil {
return nil, fmt.Errorf("unable to fetch public key while creating signer: %w", err)
}
// crv.Verifier is set here to enable storing the public key & hash algorithm together,
// as well as using the in memory Verifier to perform the verify operations.
switch kv.Algorithm {
case kmspb.CryptoKeyVersion_EC_SIGN_P256_SHA256:
crv.Verifier, err = signature.LoadECDSAVerifier(pubKey.(*ecdsa.PublicKey), myhash.SHA256)
crv.HashFunc = myhash.SHA256
case kmspb.CryptoKeyVersion_EC_SIGN_P384_SHA384:
crv.Verifier, err = signature.LoadECDSAVerifier(pubKey.(*ecdsa.PublicKey), myhash.SHA384)
crv.HashFunc = myhash.SHA384
case kmspb.CryptoKeyVersion_RSA_SIGN_PKCS1_2048_SHA256,
kmspb.CryptoKeyVersion_RSA_SIGN_PKCS1_3072_SHA256,
kmspb.CryptoKeyVersion_RSA_SIGN_PKCS1_4096_SHA256:
crv.Verifier, err = signature.LoadRSAPKCS1v15Verifier(pubKey.(*rsa.PublicKey), myhash.SHA256)
crv.HashFunc = myhash.SHA256
case kmspb.CryptoKeyVersion_RSA_SIGN_PKCS1_4096_SHA512:
crv.Verifier, err = signature.LoadRSAPKCS1v15Verifier(pubKey.(*rsa.PublicKey), myhash.SHA512)
crv.HashFunc = myhash.SHA512
case kmspb.CryptoKeyVersion_RSA_SIGN_PSS_2048_SHA256,
kmspb.CryptoKeyVersion_RSA_SIGN_PSS_3072_SHA256,
kmspb.CryptoKeyVersion_RSA_SIGN_PSS_4096_SHA256:
crv.Verifier, err = signature.LoadRSAPSSVerifier(pubKey.(*rsa.PublicKey), myhash.SHA256, nil)
crv.HashFunc = myhash.SHA256
case kmspb.CryptoKeyVersion_RSA_SIGN_PSS_4096_SHA512:
crv.Verifier, err = signature.LoadRSAPSSVerifier(pubKey.(*rsa.PublicKey), myhash.SHA512, nil)
crv.HashFunc = myhash.SHA512
default:
return nil, errors.New("unknown algorithm specified by KMS")
}
if err != nil {
return nil, fmt.Errorf("initializing internal verifier: %w", err)
}
return &crv, nil
}
func (g *gcpClient) fetchPublicKey(ctx context.Context, name string) (crypto.PublicKey, error) {
// Build the request.
pkreq := &kmspb.GetPublicKeyRequest{Name: name}
// Call the API.
pk, err := g.kmsClient.GetPublicKey(ctx, pkreq)
if err != nil {
return nil, fmt.Errorf("public key: %w", err)
}
return cryptoutils.UnmarshalPEMToPublicKey([]byte(pk.GetPem()))
}
func (g *gcpClient) getHashFunc() (myhash.Hash, error) {
ckv, err := g.getCKV()
if err != nil {
return 0, err
}
return ckv.HashFunc, nil
}
// getCKV gets the latest CryptoKeyVersion from the client's cache, which may trigger an actual
// call to GCP if the existing entry in the cache has expired.
func (g *gcpClient) getCKV() (*cryptoKeyVersion, error) {
var lerr error
loader := ttlcache.LoaderFunc[string, cryptoKeyVersion](
func(c *ttlcache.Cache[string, cryptoKeyVersion], key string) *ttlcache.Item[string, cryptoKeyVersion] {
var ttl time.Duration
var data *cryptoKeyVersion
// if we're given an explicit version, cache this value forever
if g.version != "" {
ttl = time.Second * 0
} else {
ttl = time.Second * 300
}
data, lerr = g.keyVersionName(context.Background())
if lerr == nil {
return c.Set(key, *data, ttl)
}
return nil
},
)
// we get once and use consistently to ensure the cache value doesn't change underneath us
item := g.kvCache.Get(cacheKey, ttlcache.WithLoader[string, cryptoKeyVersion](loader))
if item != nil {
v := item.Value()
return &v, nil
}
return nil, lerr
}
func (g *gcpClient) sign(ctx context.Context, digest []byte, alg myhash.Hash, crc uint32) ([]byte, error) {
ckv, err := g.getCKV()
if err != nil {
return nil, err
}
gcpSignReq := kmspb.AsymmetricSignRequest{
Name: ckv.CryptoKeyVersion.Name,
Digest: &kmspb.Digest{},
}
if crc != 0 {
gcpSignReq.DigestCrc32C = wrapperspb.Int64(int64(crc))
}
switch alg {
case myhash.SHA256:
gcpSignReq.Digest.Digest = &kmspb.Digest_Sha256{
Sha256: digest,
}
case myhash.SHA384:
gcpSignReq.Digest.Digest = &kmspb.Digest_Sha384{
Sha384: digest,
}
case myhash.SHA512:
gcpSignReq.Digest.Digest = &kmspb.Digest_Sha512{
Sha512: digest,
}
default:
return nil, errors.New("unsupported hash function")
}
resp, err := g.kmsClient.AsymmetricSign(ctx, &gcpSignReq)
if err != nil {
return nil, fmt.Errorf("calling GCP AsymmetricSign: %w", err)
}
// Optional, but recommended: perform integrity verification on result.
// For more details on ensuring E2E in-transit integrity to and from Cloud KMS visit:
// https://cloud.google.com/kms/docs/data-integrity-guidelines
if crc != 0 && !resp.VerifiedDigestCrc32C {
return nil, fmt.Errorf("AsymmetricSign: request corrupted in-transit")
}
if int64(crc32.Checksum(resp.Signature, crc32.MakeTable(crc32.Castagnoli))) != resp.SignatureCrc32C.Value {
return nil, fmt.Errorf("AsymmetricSign: response corrupted in-transit")
}
return resp.Signature, nil
}
func (g *gcpClient) public(ctx context.Context) (crypto.PublicKey, error) {
crv, err := g.getCKV()
if err != nil {
return nil, fmt.Errorf("transient error getting info from KMS: %w", err)
}
return crv.Verifier.PublicKey(options.WithContext(ctx))
}
func (g *gcpClient) verify(sig, message io.Reader, opts ...signature.VerifyOption) error {
crv, err := g.getCKV()
if err != nil {
return fmt.Errorf("transient error getting info from KMS: %w", err)
}
if err := crv.Verifier.VerifySignature(sig, message, opts...); err != nil {
// key could have been rotated, clear cache and try again if we're not pinned to a version
if g.version == "" {
g.kvCache.Delete(cacheKey)
crv, err = g.getCKV()
if err != nil {
return fmt.Errorf("transient error getting info from KMS: %w", err)
}
return crv.Verifier.VerifySignature(sig, message, opts...)
}
return fmt.Errorf("failed to verify for fixed version: %w", err)
}
return nil
}
func (g *gcpClient) createKey(ctx context.Context, algorithm string) (crypto.PublicKey, error) {
if err := g.createKeyRing(ctx); err != nil {
return nil, fmt.Errorf("creating key ring: %w", err)
}
getKeyRequest := &kmspb.GetCryptoKeyRequest{
Name: fmt.Sprintf("projects/%s/locations/%s/keyRings/%s/cryptoKeys/%s", g.projectID, g.locationID, g.keyRing, g.keyName),
}
if _, err := g.kmsClient.GetCryptoKey(ctx, getKeyRequest); err == nil {
return g.public(ctx)
}
if _, ok := algorithmMap[algorithm]; !ok {
return nil, errors.New("unknown algorithm requested")
}
createKeyRequest := &kmspb.CreateCryptoKeyRequest{
Parent: fmt.Sprintf("projects/%s/locations/%s/keyRings/%s", g.projectID, g.locationID, g.keyRing),
CryptoKeyId: g.keyName,
CryptoKey: &kmspb.CryptoKey{
Purpose: kmspb.CryptoKey_ASYMMETRIC_SIGN,
VersionTemplate: &kmspb.CryptoKeyVersionTemplate{
Algorithm: algorithmMap[algorithm],
},
},
}
if _, err := g.kmsClient.CreateCryptoKey(ctx, createKeyRequest); err != nil {
return nil, fmt.Errorf("creating crypto key: %w", err)
}
return g.public(ctx)
}
func (g *gcpClient) createKeyRing(ctx context.Context) error {
getKeyRingRequest := &kmspb.GetKeyRingRequest{
Name: fmt.Sprintf("projects/%s/locations/%s/keyRings/%s", g.projectID, g.locationID, g.keyRing),
}
if result, err := g.kmsClient.GetKeyRing(ctx, getKeyRingRequest); err == nil {
log.Printf("Key ring %s already exists in GCP KMS, moving on to creating key.\n", result.GetName())
// key ring already exists, no need to create
return nil
}
// try to create key ring
createKeyRingRequest := &kmspb.CreateKeyRingRequest{
Parent: fmt.Sprintf("projects/%s/locations/%s", g.projectID, g.locationID),
KeyRingId: g.keyRing,
}
result, err := g.kmsClient.CreateKeyRing(ctx, createKeyRingRequest)
log.Printf("Created key ring %s in GCP KMS.\n", result.GetName())
return err
}