diff options
Diffstat (limited to 'Python/random.c')
| -rw-r--r-- | Python/random.c | 129 |
1 files changed, 74 insertions, 55 deletions
diff --git a/Python/random.c b/Python/random.c index 945269a..7d37fe9 100644 --- a/Python/random.c +++ b/Python/random.c @@ -39,10 +39,9 @@ win32_urandom_init(int raise) return 0; error: - if (raise) + if (raise) { PyErr_SetFromWindowsErr(0); - else - Py_FatalError("Failed to initialize Windows random API (CryptoGen)"); + } return -1; } @@ -55,8 +54,9 @@ win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise) if (hCryptProv == 0) { - if (win32_urandom_init(raise) == -1) + if (win32_urandom_init(raise) == -1) { return -1; + } } while (size > 0) @@ -65,11 +65,9 @@ win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise) if (!CryptGenRandom(hCryptProv, (DWORD)chunk, buffer)) { /* CryptGenRandom() failed */ - if (raise) + if (raise) { PyErr_SetFromWindowsErr(0); - else - Py_FatalError("Failed to initialized the randomized hash " - "secret using CryptoGen)"); + } return -1; } buffer += chunk; @@ -86,29 +84,28 @@ win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise) /* Fill buffer with size pseudo-random bytes generated by getentropy(). Return 0 on success, or raise an exception and return -1 on error. - If fatal is nonzero, call Py_FatalError() instead of raising an exception - on error. */ + If raise is zero, don't raise an exception on error. */ static int -py_getentropy(unsigned char *buffer, Py_ssize_t size, int fatal) +py_getentropy(char *buffer, Py_ssize_t size, int raise) { while (size > 0) { Py_ssize_t len = Py_MIN(size, 256); int res; - if (!fatal) { + if (raise) { Py_BEGIN_ALLOW_THREADS res = getentropy(buffer, len); Py_END_ALLOW_THREADS - - if (res < 0) { - PyErr_SetFromErrno(PyExc_OSError); - return -1; - } } else { res = getentropy(buffer, len); - if (res < 0) - Py_FatalError("getentropy() failed"); + } + + if (res < 0) { + if (raise) { + PyErr_SetFromErrno(PyExc_OSError); + } + return -1; } buffer += len; @@ -195,18 +192,15 @@ py_getrandom(void *buffer, Py_ssize_t size, int raise) if (errno == EINTR) { if (PyErr_CheckSignals()) { - if (!raise) - Py_FatalError("getrandom() interrupted by a signal"); return -1; } /* retry getrandom() */ continue; } - if (raise) + if (raise) { PyErr_SetFromErrno(PyExc_OSError); - else - Py_FatalError("getrandom() failed"); + } return -1; } @@ -225,9 +219,9 @@ static struct { /* Read size bytes from /dev/urandom into buffer. - Call Py_FatalError() on error. */ -static void -dev_urandom_noraise(unsigned char *buffer, Py_ssize_t size) + 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; @@ -235,31 +229,35 @@ dev_urandom_noraise(unsigned char *buffer, Py_ssize_t size) assert (0 < size); #ifdef PY_GETRANDOM - if (py_getrandom(buffer, size, 0) == 1) - return; + 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) - Py_FatalError("Failed to open /dev/urandom"); + if (fd < 0) { + return -1; + } while (0 < size) { do { n = read(fd, buffer, (size_t)size); } while (n < 0 && errno == EINTR); - if (n <= 0) - { + + if (n <= 0) { /* stop on error or if read(size) returned 0 */ - Py_FatalError("Failed to read bytes from /dev/urandom"); - break; + return -1; } + buffer += n; size -= n; } close(fd); + + return 0; } /* Read size bytes from /dev/urandom into buffer. @@ -379,31 +377,51 @@ lcg_urandom(unsigned int x0, unsigned char *buffer, size_t size) } } -/* 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. - - Return 0 on success, raise an exception and return -1 on error. */ -int -_PyOS_URandom(void *buffer, Py_ssize_t size) +/* 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. */ +static int +pyurandom(void *buffer, Py_ssize_t size, int raise) { if (size < 0) { - PyErr_Format(PyExc_ValueError, - "negative argument not allowed"); + if (raise) { + PyErr_Format(PyExc_ValueError, + "negative argument not allowed"); + } return -1; } - if (size == 0) + + if (size == 0) { return 0; + } #ifdef MS_WINDOWS - return win32_urandom((unsigned char *)buffer, size, 1); + return win32_urandom((unsigned char *)buffer, size, raise); #elif defined(PY_GETENTROPY) - return py_getentropy(buffer, size, 0); + return py_getentropy(buffer, size, raise); #else - return dev_urandom_python((char*)buffer, size); + if (raise) { + return dev_urandom_python(buffer, size); + } + else { + return dev_urandom_noraise(buffer, size); + } #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. + + 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); +} + void _PyRandom_Init(void) { @@ -442,13 +460,14 @@ _PyRandom_Init(void) } } else { -#ifdef MS_WINDOWS - (void)win32_urandom(secret, secret_size, 0); -#elif defined(PY_GETENTROPY) - (void)py_getentropy(secret, secret_size, 1); -#else - dev_urandom_noraise(secret, secret_size); -#endif + int res; + + /* _PyRandom_Init() is called very early in the Python initialization + * and so exceptions cannot be used. */ + res = pyurandom(secret, secret_size, 0); + if (res < 0) { + Py_FatalError("failed to get random numbers to initialize Python"); + } } } |