{{ message }}
-
-
Notifications
You must be signed in to change notification settings - Fork 35.4k
Expand file tree
/
Copy pathbootstrap_hash.c
More file actions
623 lines (530 loc) · 18.2 KB
/
Copy pathbootstrap_hash.c
File metadata and controls
623 lines (530 loc) · 18.2 KB
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
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
#include "Python.h"
#include "pycore_initconfig.h"
#ifdef MS_WINDOWS
# include <windows.h>
/* All sample MSDN wincrypt programs include the header below. It is at least
* required with Min GW. */
# include <wincrypt.h>
#else
# include <fcntl.h>
# ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
# endif
# ifdef HAVE_LINUX_RANDOM_H
# include <linux/random.h>
# endif
# if defined(HAVE_SYS_RANDOM_H) && (defined(HAVE_GETRANDOM) || defined(HAVE_GETENTROPY))
# include <sys/random.h>
# endif
# if !defined(HAVE_GETRANDOM) && defined(HAVE_GETRANDOM_SYSCALL)
# include <sys/syscall.h>
# endif
#endif
#ifdef _Py_MEMORY_SANITIZER
# include <sanitizer/msan_interface.h>
#endif
#if defined(__APPLE__) && defined(__has_builtin)
# if __has_builtin(__builtin_available)
# define HAVE_GETENTRYPY_GETRANDOM_RUNTIME __builtin_available(macOS 10.12, iOS 10.10, tvOS 10.0, watchOS 3.0, *)
# endif
#endif
#ifndef HAVE_GETENTRYPY_GETRANDOM_RUNTIME
# define HAVE_GETENTRYPY_GETRANDOM_RUNTIME 1
#endif
#ifdef Py_DEBUG
int _Py_HashSecret_Initialized = 0;
#else
static int _Py_HashSecret_Initialized = 0;
#endif
#ifdef MS_WINDOWS
static HCRYPTPROV hCryptProv = 0;
static int
win32_urandom_init(int raise)
{
/* Acquire context */
if (!CryptAcquireContextW(&hCryptProv, NULL, NULL,
PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
goto error;
return 0;
error:
if (raise) {
PyErr_SetFromWindowsErr(0);
}
return -1;
}
/* Fill buffer with size pseudo-random bytes generated by the Windows CryptoGen
API. Return 0 on success, or raise an exception and return -1 on error. */
static int
win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise)
{
if (hCryptProv == 0)
{
if (win32_urandom_init(raise) == -1) {
return -1;
}
}
while (size > 0)
{
DWORD chunk = (DWORD)Py_MIN(size, PY_DWORD_MAX);
if (!CryptGenRandom(hCryptProv, chunk, buffer))
{
/* CryptGenRandom() failed */
if (raise) {
PyErr_SetFromWindowsErr(0);
}
return -1;
}
buffer += chunk;
size -= chunk;
}
return 0;
}
#else /* !MS_WINDOWS */
#if defined(HAVE_GETRANDOM) || defined(HAVE_GETRANDOM_SYSCALL)
#define PY_GETRANDOM 1
/* Call getrandom() to get random bytes:
- Return 1 on success
- Return 0 if getrandom() is not available (failed with ENOSYS or EPERM),
or if getrandom(GRND_NONBLOCK) failed with EAGAIN (system urandom not
initialized yet) and raise=0.
- Raise an exception (if raise is non-zero) and return -1 on error:
if getrandom() failed with EINTR, raise is non-zero and the Python signal
handler raised an exception, or if getrandom() failed with a different
error.
getrandom() is retried if it failed with EINTR: interrupted by a signal. */
static int
py_getrandom(void *buffer, Py_ssize_t size, int blocking, int raise)
{
/* Is getrandom() supported by the running kernel? Set to 0 if getrandom()
failed with ENOSYS or EPERM. Need Linux kernel 3.17 or newer, or Solaris
11.3 or newer */
static int getrandom_works = 1;
int flags;
char *dest;
long n;
if (!getrandom_works) {
return 0;
}
flags = blocking ? 0 : GRND_NONBLOCK;
dest = buffer;
while (0 < size) {
#if defined(__sun) && defined(__SVR4)
/* Issue #26735: On Solaris, getrandom() is limited to returning up
to 1024 bytes. Call it multiple times if more bytes are
requested. */
n = Py_MIN(size, 1024);
#else
n = Py_MIN(size, LONG_MAX);
#endif
errno = 0;
#ifdef HAVE_GETRANDOM
if (raise) {
Py_BEGIN_ALLOW_THREADS
n = getrandom(dest, n, flags);
Py_END_ALLOW_THREADS
}
else {
n = getrandom(dest, n, flags);
}
#else
/* On Linux, use the syscall() function because the GNU libc doesn't
expose the Linux getrandom() syscall yet. See:
https://sourceware.org/bugzilla/show_bug.cgi?id=17252 */
if (raise) {
Py_BEGIN_ALLOW_THREADS
n = syscall(SYS_getrandom, dest, n, flags);
Py_END_ALLOW_THREADS
}
else {
n = syscall(SYS_getrandom, dest, n, flags);
}
# ifdef _Py_MEMORY_SANITIZER
if (n > 0) {
__msan_unpoison(dest, n);
}
# endif
#endif
if (n < 0) {
/* ENOSYS: the syscall is not supported by the kernel.
EPERM: the syscall is blocked by a security policy (ex: SECCOMP)
or something else. */
if (errno == ENOSYS || errno == EPERM) {
getrandom_works = 0;
return 0;
}
/* getrandom(GRND_NONBLOCK) fails with EAGAIN if the system urandom
is not initialized yet. For _PyRandom_Init(), we ignore the
error and fall back on reading /dev/urandom which never blocks,
even if the system urandom is not initialized yet:
see the PEP 524. */
if (errno == EAGAIN && !raise && !blocking) {
return 0;
}
if (errno == EINTR) {
if (raise) {
if (PyErr_CheckSignals()) {
return -1;
}
}
/* retry getrandom() if it was interrupted by a signal */
continue;
}
if (raise) {
PyErr_SetFromErrno(PyExc_OSError);
}
return -1;
}
dest += n;
size -= n;
}
return 1;
}
#elif defined(HAVE_GETENTROPY)
#define PY_GETENTROPY 1
/* Fill buffer with size pseudo-random bytes generated by getentropy():
- Return 1 on success
- Return 0 if getentropy() syscall is not available (failed with ENOSYS or
EPERM).
- Raise an exception (if raise is non-zero) and return -1 on error:
if getentropy() failed with EINTR, raise is non-zero and the Python signal
handler raised an exception, or if getentropy() failed with a different
error.
getentropy() is retried if it failed with EINTR: interrupted by a signal. */
#if defined(__APPLE__) && defined(__has_attribute) && __has_attribute(availability)
static int
py_getentropy(char *buffer, Py_ssize_t size, int raise)
__attribute__((availability(macos,introduced=10.12)))
__attribute__((availability(ios,introduced=10.0)))
__attribute__((availability(tvos,introduced=10.0)))
__attribute__((availability(watchos,introduced=3.0)));
#endif
static int
py_getentropy(char *buffer, Py_ssize_t size, int raise)
{
/* Is getentropy() supported by the running kernel? Set to 0 if
getentropy() failed with ENOSYS or EPERM. */
static int getentropy_works = 1;
if (!getentropy_works) {
return 0;
}
while (size > 0) {
/* getentropy() is limited to returning up to 256 bytes. Call it
multiple times if more bytes are requested. */
Py_ssize_t len = Py_MIN(size, 256);
int res;
if (raise) {
Py_BEGIN_ALLOW_THREADS
res = getentropy(buffer, len);
Py_END_ALLOW_THREADS
}
else {
res = getentropy(buffer, len);
}
if (res < 0) {
/* ENOSYS: the syscall is not supported by the running kernel.
EPERM: the syscall is blocked by a security policy (ex: SECCOMP)
or something else. */
if (errno == ENOSYS || errno == EPERM) {
getentropy_works = 0;
return 0;
}
if (errno == EINTR) {
if (raise) {
if (PyErr_CheckSignals()) {
return -1;
}
}
/* retry getentropy() if it was interrupted by a signal */
continue;
}
if (raise) {
PyErr_SetFromErrno(PyExc_OSError);
}
return -1;
}
buffer += len;
size -= len;
}
return 1;
}
#endif /* defined(HAVE_GETENTROPY) && !(defined(__sun) && defined(__SVR4)) */
static struct {
int fd;
dev_t st_dev;
ino_t st_ino;
} urandom_cache = { -1 };
/* Read random bytes from the /dev/urandom device:
- Return 0 on success
- Raise an exception (if raise is non-zero) and return -1 on error
Possible causes of errors:
- open() failed with ENOENT, ENXIO, ENODEV, EACCES: the /dev/urandom device
was not found. For example, it was removed manually or not exposed in a
chroot or container.
- open() failed with a different error
- fstat() failed
- read() failed or returned 0
read() is retried if it failed with EINTR: interrupted by a signal.
The file descriptor of the device is kept open between calls to avoid using
many file descriptors when run in parallel from multiple threads:
see the issue #18756.
st_dev and st_ino fields of the file descriptor (from fstat()) are cached to
check if the file descriptor was replaced by a different file (which is
likely a bug in the application): see the issue #21207.
If the file descriptor was closed or replaced, open a new file descriptor
but don't close the old file descriptor: it probably points to something
important for some third-party code. */
static int
dev_urandom(char *buffer, Py_ssize_t size, int raise)
{
int fd;
Py_ssize_t n;
if (raise) {
struct _Py_stat_struct st;
int fstat_result;
if (urandom_cache.fd >= 0) {
Py_BEGIN_ALLOW_THREADS
fstat_result = _Py_fstat_noraise(urandom_cache.fd, &st);
Py_END_ALLOW_THREADS
/* Does the fd point to the same thing as before? (issue #21207) */
if (fstat_result
|| st.st_dev != urandom_cache.st_dev
|| st.st_ino != urandom_cache.st_ino) {
/* Something changed: forget the cached fd (but don't close it,
since it probably points to something important for some
third-party code). */
urandom_cache.fd = -1;
}
}
if (urandom_cache.fd >= 0)
fd = urandom_cache.fd;
else {
fd = _Py_open("/dev/urandom", O_RDONLY);
if (fd < 0) {
if (errno == ENOENT || errno == ENXIO ||
errno == ENODEV || errno == EACCES) {
PyErr_SetString(PyExc_NotImplementedError,
"/dev/urandom (or equivalent) not found");
}
/* otherwise, keep the OSError exception raised by _Py_open() */
return -1;
}
if (urandom_cache.fd >= 0) {
/* urandom_fd was initialized by another thread while we were
not holding the GIL, keep it. */
close(fd);
fd = urandom_cache.fd;
}
else {
if (_Py_fstat(fd, &st)) {
close(fd);
return -1;
}
else {
urandom_cache.fd = fd;
urandom_cache.st_dev = st.st_dev;
urandom_cache.st_ino = st.st_ino;
}
}
}
do {
n = _Py_read(fd, buffer, (size_t)size);
if (n == -1)
return -1;
if (n == 0) {
PyErr_Format(PyExc_RuntimeError,
"Failed to read %zi bytes from /dev/urandom",
size);
return -1;
}
buffer += n;
size -= n;
} while (0 < size);
}
else {
fd = _Py_open_noraise("/dev/urandom", O_RDONLY);
if (fd < 0) {
return -1;
}
while (0 < size)
{
do {
n = read(fd, buffer, (size_t)size);
} while (n < 0 && errno == EINTR);
if (n <= 0) {
/* stop on error or if read(size) returned 0 */
close(fd);
return -1;
}
buffer += n;
size -= n;
}
close(fd);
}
return 0;
}
static void
dev_urandom_close(void)
{
if (urandom_cache.fd >= 0) {
close(urandom_cache.fd);
urandom_cache.fd = -1;
}
}
#endif /* !MS_WINDOWS */
/* Fill buffer with pseudo-random bytes generated by a linear congruent
generator (LCG):
x(n+1) = (x(n) * 214013 + 2531011) % 2^32
Use bits 23..16 of x(n) to generate a byte. */
static void
lcg_urandom(unsigned int x0, unsigned char *buffer, size_t size)
{
size_t index;
unsigned int x;
x = x0;
for (index=0; index < size; index++) {
x *= 214013;
x += 2531011;
/* modulo 2 ^ (8 * sizeof(int)) */
buffer[index] = (x >> 16) & 0xff;
}
}
/* Read random bytes:
- Return 0 on success
- Raise an exception (if raise is non-zero) and return -1 on error
Used sources of entropy ordered by preference, preferred source first:
- CryptGenRandom() on Windows
- getrandom() function (ex: Linux and Solaris): call py_getrandom()
- getentropy() function (ex: OpenBSD): call py_getentropy()
- /dev/urandom device
Read from the /dev/urandom device if getrandom() or getentropy() function
is not available or does not work.
Prefer getrandom() over getentropy() because getrandom() supports blocking
and non-blocking mode: see the PEP 524. Python requires non-blocking RNG at
startup to initialize its hash secret, but os.urandom() must block until the
system urandom is initialized (at least on Linux 3.17 and newer).
Prefer getrandom() and getentropy() over reading directly /dev/urandom
because these functions don't need file descriptors and so avoid ENFILE or
EMFILE errors (too many open files): see the issue #18756.
Only the getrandom() function supports non-blocking mode.
Only use RNG running in the kernel. They are more secure because it is
harder to get the internal state of a RNG running in the kernel land than a
RNG running in the user land. The kernel has a direct access to the hardware
and has access to hardware RNG, they are used as entropy sources.
Note: the OpenSSL RAND_pseudo_bytes() function does not automatically reseed
its RNG on fork(), two child processes (with the same pid) generate the same
random numbers: see issue #18747. Kernel RNGs don't have this issue,
they have access to good quality entropy sources.
If raise is zero:
- Don't raise an exception on error
- Don't call the Python signal handler (don't call PyErr_CheckSignals()) if
a function fails with EINTR: retry directly the interrupted function
- Don't release the GIL to call functions.
*/
static int
pyurandom(void *buffer, Py_ssize_t size, int blocking, int raise)
{
#if defined(PY_GETRANDOM) || defined(PY_GETENTROPY)
int res;
#endif
if (size < 0) {
if (raise) {
PyErr_Format(PyExc_ValueError,
"negative argument not allowed");
}
return -1;
}
if (size == 0) {
return 0;
}
#ifdef MS_WINDOWS
return win32_urandom((unsigned char *)buffer, size, raise);
#else
#if defined(PY_GETRANDOM) || defined(PY_GETENTROPY)
if (HAVE_GETENTRYPY_GETRANDOM_RUNTIME) {
#ifdef PY_GETRANDOM
res = py_getrandom(buffer, size, blocking, raise);
#else
res = py_getentropy(buffer, size, raise);
#endif
if (res < 0) {
return -1;
}
if (res == 1) {
return 0;
}
/* getrandom() or getentropy() function is not available: failed with
ENOSYS or EPERM. Fall back on reading from /dev/urandom. */
} /* end of availability block */
#endif
return dev_urandom(buffer, size, raise);
#endif
}
/* Fill buffer with size pseudo-random bytes from the operating system random
number generator (RNG). It is suitable for most cryptographic purposes
except long living private keys for asymmetric encryption.
On Linux 3.17 and newer, the getrandom() syscall is used in blocking mode:
block until the system urandom entropy pool is initialized (128 bits are
collected by the kernel).
Return 0 on success. Raise an exception and return -1 on error. */
int
_PyOS_URandom(void *buffer, Py_ssize_t size)
{
return pyurandom(buffer, size, 1, 1);
}
/* Fill buffer with size pseudo-random bytes from the operating system random
number generator (RNG). It is not suitable for cryptographic purpose.
On Linux 3.17 and newer (when getrandom() syscall is used), if the system
urandom is not initialized yet, the function returns "weak" entropy read
from /dev/urandom.
Return 0 on success. Raise an exception and return -1 on error. */
int
_PyOS_URandomNonblock(void *buffer, Py_ssize_t size)
{
return pyurandom(buffer, size, 0, 1);
}
PyStatus
_Py_HashRandomization_Init(const PyConfig *config)
{
void *secret = &_Py_HashSecret;
Py_ssize_t secret_size = sizeof(_Py_HashSecret_t);
if (_Py_HashSecret_Initialized) {
return _PyStatus_OK();
}
_Py_HashSecret_Initialized = 1;
if (config->use_hash_seed) {
if (config->hash_seed == 0) {
/* disable the randomized hash */
memset(secret, 0, secret_size);
}
else {
/* use the specified hash seed */
lcg_urandom(config->hash_seed, secret, secret_size);
}
}
else {
/* use a random hash seed */
int res;
/* _PyRandom_Init() is called very early in the Python initialization
and so exceptions cannot be used (use raise=0).
_PyRandom_Init() must not block Python initialization: call
pyurandom() is non-blocking mode (blocking=0): see the PEP 524. */
res = pyurandom(secret, secret_size, 0, 0);
if (res < 0) {
return _PyStatus_ERR("failed to get random numbers "
"to initialize Python");
}
}
return _PyStatus_OK();
}
void
_Py_HashRandomization_Fini(void)
{
#ifdef MS_WINDOWS
if (hCryptProv) {
CryptReleaseContext(hCryptProv, 0);
hCryptProv = 0;
}
#else
dev_urandom_close();
#endif
}
You can’t perform that action at this time.