@recaptime-dev's working patches + fork for Phorge, a community fork of Phabricator. (Upstream dev and stable branches are at upstream/main and upstream/stable respectively.)
hq.recaptime.dev/wiki/Phorge
phorge
phabricator
Store and verify content integrity checksums for files
Summary:
Ref T12470. This helps defuse attacks where an adversary can directly take control of whatever storage engine files are being stored in and change data there. These attacks would require a significant level of access.
Such attackers could potentially attack ranges of AES-256-CBC encrypted files by using Phabricator as a decryption oracle if they were also able to compromise a Phabricator account with read access to the files.
By storing a hash of the data (and, in the case of AES-256-CBC files, the IV) when we write files, and verifying it before we decrypt or read them, we can detect and prevent this kind of tampering.
This also helps detect mundane corruption and integrity issues.
Test Plan:
- Added unit tests.
- Uploaded new files, saw them get integrity hashes.
- Manually corrupted file data, saw it fail. Used `bin/files cat --salvage` to read it anyway.
- Tampered with IVs, saw integrity failures.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T12470
Differential Revision: https://secure.phabricator.com/D17625
+135
-6
+2
src/__phutil_library_map__.php
+2
src/__phutil_library_map__.php
···
2762
2762
'PhabricatorFileImageProxyController' => 'applications/files/controller/PhabricatorFileImageProxyController.php',
2763
2763
'PhabricatorFileImageTransform' => 'applications/files/transform/PhabricatorFileImageTransform.php',
2764
2764
'PhabricatorFileInfoController' => 'applications/files/controller/PhabricatorFileInfoController.php',
2765
+
'PhabricatorFileIntegrityException' => 'applications/files/exception/PhabricatorFileIntegrityException.php',
2765
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'PhabricatorFileLightboxController' => 'applications/files/controller/PhabricatorFileLightboxController.php',
2766
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'PhabricatorFileLinkView' => 'view/layout/PhabricatorFileLinkView.php',
2767
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'PhabricatorFileListController' => 'applications/files/controller/PhabricatorFileListController.php',
···
7891
7892
'PhabricatorFileImageProxyController' => 'PhabricatorFileController',
7892
7893
'PhabricatorFileImageTransform' => 'PhabricatorFileTransform',
7893
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'PhabricatorFileInfoController' => 'PhabricatorFileController',
7895
+
'PhabricatorFileIntegrityException' => 'Exception',
7894
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'PhabricatorFileLightboxController' => 'PhabricatorFileController',
7895
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'PhabricatorFileLinkView' => 'AphrontTagView',
7896
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'PhabricatorFileListController' => 'PhabricatorFileController',
+24
src/applications/files/engine/PhabricatorFileStorageEngine.php
+24
src/applications/files/engine/PhabricatorFileStorageEngine.php
···
332
332
PhabricatorFileStorageFormat $format) {
333
333
334
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$formatted_data = $this->readFile($file->getStorageHandle());
335
+
336
+
$known_integrity = $file->getIntegrityHash();
337
+
if ($known_integrity !== null) {
338
+
$new_integrity = $this->newIntegrityHash($formatted_data, $format);
339
+
if ($known_integrity !== $new_integrity) {
340
+
throw new PhabricatorFileIntegrityException(
341
+
pht(
342
+
'File data integrity check failed. Dark forces have corrupted '.
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+
'or tampered with this file. The file data can not be read.'));
344
+
}
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+
}
346
+
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$formatted_data = array($formatted_data);
336
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$data = '';
···
349
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}
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return array($data);
364
+
}
365
+
366
+
public function newIntegrityHash(
367
+
$data,
368
+
PhabricatorFileStorageFormat $format) {
369
+
370
+
$data_hash = PhabricatorHash::digest($data);
371
+
$format_hash = $format->newFormatIntegrityHash();
372
+
373
+
$full_hash = "{$data_hash}/{$format_hash}";
374
+
375
+
return PhabricatorHash::digest($full_hash);
352
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}
353
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}
+4
src/applications/files/engine/PhabricatorTestStorageEngine.php
+4
src/applications/files/engine/PhabricatorTestStorageEngine.php
+4
src/applications/files/exception/PhabricatorFileIntegrityException.php
+4
src/applications/files/exception/PhabricatorFileIntegrityException.php
+14
src/applications/files/format/PhabricatorFileAES256StorageFormat.php
+14
src/applications/files/format/PhabricatorFileAES256StorageFormat.php
···
56
56
return array($data);
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}
58
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+
public function newFormatIntegrityHash() {
60
+
$file = $this->getFile();
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+
list($key_envelope, $iv_envelope) = $this->extractKeyAndIV($file);
62
+
63
+
// NOTE: We include the IV in the format integrity hash. If we do not,
64
+
// attackers can potentially forge the first block of decrypted data
65
+
// in CBC mode if they are able to substitute a chosen IV and predict
66
+
// the plaintext. (Normally, they can not tamper with the IV.)
67
+
68
+
$input = self::FORMATKEY.'/iv:'.$iv_envelope->openEnvelope();
69
+
70
+
return PhabricatorHash::digest($input);
71
+
}
72
+
59
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public function newStorageProperties() {
60
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// Generate a unique key and IV for this block of data.
61
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$key_envelope = self::newAES256Key();
+4
src/applications/files/format/PhabricatorFileStorageFormat.php
+4
src/applications/files/format/PhabricatorFileStorageFormat.php
+33
src/applications/files/format/__tests__/PhabricatorFileStorageFormatTestCase.php
+33
src/applications/files/format/__tests__/PhabricatorFileStorageFormatTestCase.php
···
92
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}
93
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$this->assertEqual('cow jumped', $raw_data);
94
94
}
95
+
96
+
public function testStorageTampering() {
97
+
$engine = new PhabricatorTestStorageEngine();
98
+
99
+
$good = 'The cow jumped over the full moon.';
100
+
$evil = 'The cow slept quietly, honoring the glorious dictator.';
101
+
102
+
$params = array(
103
+
'name' => 'message.txt',
104
+
'storageEngines' => array(
105
+
$engine,
106
+
),
107
+
);
108
+
109
+
// First, write the file normally.
110
+
$file = PhabricatorFile::newFromFileData($good, $params);
111
+
$this->assertEqual($good, $file->loadFileData());
112
+
113
+
// As an adversary, tamper with the file.
114
+
$engine->tamperWithFile($file->getStorageHandle(), $evil);
115
+
116
+
// Attempts to read the file data should now fail the integrity check.
117
+
$caught = null;
118
+
try {
119
+
$file->loadFileData();
120
+
} catch (PhabricatorFileIntegrityException $ex) {
121
+
$caught = $ex;
122
+
}
123
+
124
+
$this->assertTrue($caught instanceof PhabricatorFileIntegrityException);
125
+
}
126
+
127
+
95
128
}
+29
-3
src/applications/files/management/PhabricatorFilesManagementCatWorkflow.php
+29
-3
src/applications/files/management/PhabricatorFilesManagementCatWorkflow.php
···
20
20
'help' => pht('End printing at a specific offset.'),
21
21
),
22
22
array(
23
+
'name' => 'salvage',
24
+
'help' => pht(
25
+
'DANGEROUS. Attempt to salvage file content even if the '.
26
+
'integrity check fails. If an adversary has tampered with '.
27
+
'the file, the conent may be unsafe.'),
28
+
),
29
+
array(
23
30
'name' => 'names',
24
31
'wildcard' => true,
25
32
),
···
43
50
$begin = $args->getArg('begin');
44
51
$end = $args->getArg('end');
45
52
46
-
$iterator = $file->getFileDataIterator($begin, $end);
47
-
foreach ($iterator as $data) {
48
-
echo $data;
53
+
$file->makeEphemeral();
54
+
55
+
// If we're running in "salvage" mode, wipe out any integrity hash which
56
+
// may be present. This makes us read file data without performing an
57
+
// integrity check.
58
+
$salvage = $args->getArg('salvage');
59
+
if ($salvage) {
60
+
$file->setIntegrityHash(null);
61
+
}
62
+
63
+
try {
64
+
$iterator = $file->getFileDataIterator($begin, $end);
65
+
foreach ($iterator as $data) {
66
+
echo $data;
67
+
}
68
+
} catch (PhabricatorFileIntegrityException $ex) {
69
+
throw new PhutilArgumentUsageException(
70
+
pht(
71
+
'File data integrity check failed. Use "--salvage" to bypass '.
72
+
'integrity checks. This flag is dangerous, use it at your own '.
73
+
'risk. Underlying error: %s',
74
+
$ex->getMessage()));
49
75
}
50
76
51
77
return 0;
+21
-3
src/applications/files/storage/PhabricatorFile.php
+21
-3
src/applications/files/storage/PhabricatorFile.php
···
37
37
const METADATA_PARTIAL = 'partial';
38
38
const METADATA_PROFILE = 'profile';
39
39
const METADATA_STORAGE = 'storage';
40
+
const METADATA_INTEGRITY = 'integrity';
40
41
41
42
protected $name;
42
43
protected $mimeType;
···
324
325
325
326
$data_handle = null;
326
327
$engine_identifier = null;
328
+
$integrity_hash = null;
327
329
$exceptions = array();
328
330
foreach ($engines as $engine) {
329
331
$engine_class = get_class($engine);
330
332
try {
331
-
list($engine_identifier, $data_handle) = $file->writeToEngine(
333
+
$result = $file->writeToEngine(
332
334
$engine,
333
335
$data,
334
336
$params);
337
+
338
+
list($engine_identifier, $data_handle, $integrity_hash) = $result;
335
339
336
340
// We stored the file somewhere so stop trying to write it to other
337
341
// places.
···
362
366
363
367
$file->setStorageEngine($engine_identifier);
364
368
$file->setStorageHandle($data_handle);
369
+
370
+
$file->setIntegrityHash($integrity_hash);
365
371
366
372
$file->readPropertiesFromParameters($params);
367
373
···
409
415
'name' => $this->getName(),
410
416
);
411
417
412
-
list($new_identifier, $new_handle) = $this->writeToEngine(
418
+
list($new_identifier, $new_handle, $integrity_hash) = $this->writeToEngine(
413
419
$engine,
414
420
$data,
415
421
$params);
···
420
426
421
427
$this->setStorageEngine($new_identifier);
422
428
$this->setStorageHandle($new_handle);
429
+
$this->setIntegrityHash($integrity_hash);
423
430
$this->save();
424
431
425
432
if (!$make_copy) {
···
494
501
$formatted_iterator = $format->newWriteIterator($data_iterator);
495
502
$formatted_data = $this->loadDataFromIterator($formatted_iterator);
496
503
504
+
$integrity_hash = $engine->newIntegrityHash($formatted_data, $format);
505
+
497
506
$data_handle = $engine->writeFile($formatted_data, $params);
498
507
499
508
if (!$data_handle || strlen($data_handle) > 255) {
···
518
527
$engine_identifier));
519
528
}
520
529
521
-
return array($engine_identifier, $data_handle);
530
+
return array($engine_identifier, $data_handle, $integrity_hash);
522
531
}
523
532
524
533
···
1218
1227
public function setIsProfileImage($value) {
1219
1228
$this->metadata[self::METADATA_PROFILE] = $value;
1220
1229
return $this;
1230
+
}
1231
+
1232
+
public function setIntegrityHash($integrity_hash) {
1233
+
$this->metadata[self::METADATA_INTEGRITY] = $integrity_hash;
1234
+
return $this;
1235
+
}
1236
+
1237
+
public function getIntegrityHash() {
1238
+
return idx($this->metadata, self::METADATA_INTEGRITY);
1221
1239
}
1222
1240
1223
1241
/**