}
/* Issue #25003: Don't use getentropy() on Solaris (available since
- * Solaris 11.3), it is blocking whereas os.urandom() should not block. */
+ Solaris 11.3), it is blocking whereas os.urandom() should not block. */
#elif defined(HAVE_GETENTROPY) && !defined(sun)
#define PY_GETENTROPY 1
#if defined(HAVE_GETRANDOM) || defined(HAVE_GETRANDOM_SYSCALL)
#define PY_GETRANDOM 1
+/* Call getrandom()
+ - Return 1 on success
+ - Return 0 if getrandom() syscall is not available (fails with ENOSYS).
+ - Raise an exception (if raise is non-zero) and return -1 on error:
+ getrandom() failed with EINTR and the Python signal handler raised an
+ exception, or getrandom() failed with a different error. */
static int
py_getrandom(void *buffer, Py_ssize_t size, int raise)
{
/* Is getrandom() supported by the running kernel?
- * Need Linux kernel 3.17 or newer, or Solaris 11.3 or newer */
+ Need Linux kernel 3.17 or newer, or Solaris 11.3 or newer */
static int getrandom_works = 1;
/* getrandom() on Linux will block if called before the kernel has
- * initialized the urandom entropy pool. This will cause Python
- * to hang on startup if called very early in the boot process -
- * see https://bugs.python.org/issue26839. To avoid this, use the
- * GRND_NONBLOCK flag. */
+ initialized the urandom entropy pool. This will cause Python
+ to hang on startup if called very early in the boot process -
+ see https://bugs.python.org/issue26839. To avoid this, use the
+ GRND_NONBLOCK flag. */
const int flags = GRND_NONBLOCK;
char *dest;
long n;
- if (!getrandom_works)
+ if (!getrandom_works) {
return 0;
+ }
dest = buffer;
while (0 < size) {
}
#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 */
+ 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);
}
if (errno == EAGAIN) {
/* If we failed with EAGAIN, the entropy pool was
- * uninitialized. In this case, we return failure to fall
- * back to reading from /dev/urandom.
- *
- * Note: In this case the data read will not be random so
- * should not be used for cryptographic purposes. Retaining
- * the existing semantics for practical purposes. */
+ uninitialized. In this case, we return failure to fall
+ back to reading from /dev/urandom.
+
+ Note: In this case the data read will not be random so
+ should not be used for cryptographic purposes. Retaining
+ the existing semantics for practical purposes. */
getrandom_works = 0;
return 0;
}
} urandom_cache = { -1 };
-/* Read size bytes from /dev/urandom into buffer.
- Return 0 success, or return -1 on error. */
-static int
-dev_urandom_noraise(char *buffer, Py_ssize_t size)
-{
- int fd;
- Py_ssize_t n;
-
- assert (0 < size);
-
-#ifdef PY_GETRANDOM
- if (py_getrandom(buffer, size, 0) == 1) {
- return 0;
- }
- /* getrandom() is not supported by the running kernel, fall back
- * on reading /dev/urandom */
-#endif
-
- 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 */
- return -1;
- }
-
- buffer += n;
- size -= n;
- }
- close(fd);
-
- return 0;
-}
+/* Read 'size' random bytes from getrandom(). Fall back on reading from
+ /dev/urandom if getrandom() is not available.
-/* Read size bytes from /dev/urandom into buffer.
- Return 0 on success, raise an exception and return -1 on error. */
+ Return 0 on success. Raise an exception (if raise is non-zero) and return -1
+ on error. */
static int
-dev_urandom_python(char *buffer, Py_ssize_t size)
+dev_urandom(char *buffer, Py_ssize_t size, int raise)
{
int fd;
Py_ssize_t n;
- struct _Py_stat_struct st;
#ifdef PY_GETRANDOM
int res;
#endif
- if (size <= 0)
- return 0;
+ assert(size > 0);
#ifdef PY_GETRANDOM
- res = py_getrandom(buffer, size, 1);
- if (res < 0)
+ res = py_getrandom(buffer, size, raise);
+ if (res < 0) {
return -1;
- if (res == 1)
+ }
+ if (res == 1) {
return 0;
+ }
/* getrandom() is not supported by the running kernel, fall back
- * on reading /dev/urandom */
+ on reading /dev/urandom */
#endif
- if (urandom_cache.fd >= 0) {
- /* Does the fd point to the same thing as before? (issue #21207) */
- if (_Py_fstat_noraise(urandom_cache.fd, &st)
- || 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 (raise) {
+ struct _Py_stat_struct st;
+
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;
+ /* Does the fd point to the same thing as before? (issue #21207) */
+ if (_Py_fstat_noraise(urandom_cache.fd, &st)
+ || 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 {
- if (_Py_fstat(fd, &st)) {
- close(fd);
+ 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 {
- urandom_cache.fd = fd;
- urandom_cache.st_dev = st.st_dev;
- urandom_cache.st_ino = st.st_ino;
+ 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);
+ 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;
}
- buffer += n;
- size -= n;
- } while (0 < size);
+ 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 */
+ return -1;
+ }
+
+ buffer += n;
+ size -= n;
+ }
+ close(fd);
+ }
return 0;
}
}
/* If raise is zero:
- * - Don't raise exceptions on error
- * - Don't call PyErr_CheckSignals() on EINTR (retry directly the interrupted
- * syscall)
- * - Don't release the GIL to call syscalls. */
+ - Don't raise exceptions on error
+ - Don't call PyErr_CheckSignals() on EINTR (retry directly the interrupted
+ syscall)
+ - Don't release the GIL to call syscalls. */
static int
pyurandom(void *buffer, Py_ssize_t size, int raise)
{
#elif defined(PY_GETENTROPY)
return py_getentropy(buffer, size, raise);
#else
- if (raise) {
- return dev_urandom_python(buffer, size);
- }
- else {
- return dev_urandom_noraise(buffer, size);
- }
+ return dev_urandom(buffer, size, raise);
#endif
}
int res;
/* _PyRandom_Init() is called very early in the Python initialization
- * and so exceptions cannot be used. */
+ and so exceptions cannot be used (use raise=0). */
res = pyurandom(secret, secret_size, 0);
if (res < 0) {
Py_FatalError("failed to get random numbers to initialize Python");
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