Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 1 | #include "Python.h" |
Victor Stinner | 871ff77 | 2019-05-17 23:54:00 +0200 | [diff] [blame] | 2 | #include "pycore_coreconfig.h" |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 3 | #ifdef MS_WINDOWS |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 4 | # include <windows.h> |
Martin Panter | d2f8747 | 2016-07-29 04:00:44 +0000 | [diff] [blame] | 5 | /* All sample MSDN wincrypt programs include the header below. It is at least |
| 6 | * required with Min GW. */ |
| 7 | # include <wincrypt.h> |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 8 | #else |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 9 | # include <fcntl.h> |
| 10 | # ifdef HAVE_SYS_STAT_H |
| 11 | # include <sys/stat.h> |
| 12 | # endif |
Victor Stinner | dddf484 | 2016-06-07 11:21:42 +0200 | [diff] [blame] | 13 | # ifdef HAVE_LINUX_RANDOM_H |
| 14 | # include <linux/random.h> |
| 15 | # endif |
Benjamin Peterson | 493ac1b | 2017-01-01 22:29:36 -0600 | [diff] [blame] | 16 | # if defined(HAVE_SYS_RANDOM_H) && (defined(HAVE_GETRANDOM) || defined(HAVE_GETENTROPY)) |
Victor Stinner | bae2d62 | 2015-10-01 09:47:30 +0200 | [diff] [blame] | 17 | # include <sys/random.h> |
Ned Deily | 7ae4112 | 2016-11-12 16:35:48 -0500 | [diff] [blame] | 18 | # endif |
| 19 | # if !defined(HAVE_GETRANDOM) && defined(HAVE_GETRANDOM_SYSCALL) |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 20 | # include <sys/syscall.h> |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 21 | # endif |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 22 | #endif |
| 23 | |
Gregory P. Smith | 3015fb8 | 2018-11-12 22:01:22 -0800 | [diff] [blame] | 24 | #ifdef _Py_MEMORY_SANITIZER |
Gregory P. Smith | 1584a00 | 2018-11-12 12:07:14 -0800 | [diff] [blame] | 25 | # include <sanitizer/msan_interface.h> |
| 26 | #endif |
| 27 | |
Benjamin Peterson | 69e9727 | 2012-02-21 11:08:50 -0500 | [diff] [blame] | 28 | #ifdef Py_DEBUG |
| 29 | int _Py_HashSecret_Initialized = 0; |
| 30 | #else |
| 31 | static int _Py_HashSecret_Initialized = 0; |
| 32 | #endif |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 33 | |
| 34 | #ifdef MS_WINDOWS |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 35 | static HCRYPTPROV hCryptProv = 0; |
| 36 | |
| 37 | static int |
| 38 | win32_urandom_init(int raise) |
| 39 | { |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 40 | /* Acquire context */ |
Martin v. Löwis | 3f50bf6 | 2013-01-25 14:06:18 +0100 | [diff] [blame] | 41 | if (!CryptAcquireContext(&hCryptProv, NULL, NULL, |
| 42 | PROV_RSA_FULL, CRYPT_VERIFYCONTEXT)) |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 43 | goto error; |
| 44 | |
| 45 | return 0; |
| 46 | |
| 47 | error: |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 48 | if (raise) { |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 49 | PyErr_SetFromWindowsErr(0); |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 50 | } |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 51 | return -1; |
| 52 | } |
| 53 | |
| 54 | /* Fill buffer with size pseudo-random bytes generated by the Windows CryptoGen |
Victor Stinner | 4d6a3d6 | 2014-12-21 01:16:38 +0100 | [diff] [blame] | 55 | API. Return 0 on success, or raise an exception and return -1 on error. */ |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 56 | static int |
| 57 | win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise) |
| 58 | { |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 59 | if (hCryptProv == 0) |
| 60 | { |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 61 | if (win32_urandom_init(raise) == -1) { |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 62 | return -1; |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 63 | } |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 64 | } |
| 65 | |
| 66 | while (size > 0) |
| 67 | { |
Victor Stinner | c48ff73 | 2018-11-22 14:43:07 +0100 | [diff] [blame] | 68 | DWORD chunk = (DWORD)Py_MIN(size, PY_DWORD_MAX); |
| 69 | if (!CryptGenRandom(hCryptProv, chunk, buffer)) |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 70 | { |
| 71 | /* CryptGenRandom() failed */ |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 72 | if (raise) { |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 73 | PyErr_SetFromWindowsErr(0); |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 74 | } |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 75 | return -1; |
| 76 | } |
| 77 | buffer += chunk; |
| 78 | size -= chunk; |
| 79 | } |
| 80 | return 0; |
| 81 | } |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 82 | |
Victor Stinner | dcdb60e | 2017-01-06 11:16:20 +0100 | [diff] [blame] | 83 | #else /* !MS_WINDOWS */ |
| 84 | |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 85 | #if defined(HAVE_GETRANDOM) || defined(HAVE_GETRANDOM_SYSCALL) |
Victor Stinner | bae2d62 | 2015-10-01 09:47:30 +0200 | [diff] [blame] | 86 | #define PY_GETRANDOM 1 |
| 87 | |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 88 | /* Call getrandom() to get random bytes: |
| 89 | |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 90 | - Return 1 on success |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 91 | - Return 0 if getrandom() is not available (failed with ENOSYS or EPERM), |
| 92 | or if getrandom(GRND_NONBLOCK) failed with EAGAIN (system urandom not |
| 93 | initialized yet) and raise=0. |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 94 | - Raise an exception (if raise is non-zero) and return -1 on error: |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 95 | if getrandom() failed with EINTR, raise is non-zero and the Python signal |
| 96 | handler raised an exception, or if getrandom() failed with a different |
| 97 | error. |
| 98 | |
| 99 | getrandom() is retried if it failed with EINTR: interrupted by a signal. */ |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 100 | static int |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 101 | py_getrandom(void *buffer, Py_ssize_t size, int blocking, int raise) |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 102 | { |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 103 | /* Is getrandom() supported by the running kernel? Set to 0 if getrandom() |
Victor Stinner | 6d8bc46 | 2016-09-20 22:46:02 +0200 | [diff] [blame] | 104 | failed with ENOSYS or EPERM. Need Linux kernel 3.17 or newer, or Solaris |
Victor Stinner | af59732 | 2016-09-20 22:26:18 +0200 | [diff] [blame] | 105 | 11.3 or newer */ |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 106 | static int getrandom_works = 1; |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 107 | int flags; |
Victor Stinner | cfb1961 | 2016-06-08 10:16:50 +0200 | [diff] [blame] | 108 | char *dest; |
Victor Stinner | ec721f3 | 2016-06-16 23:53:47 +0200 | [diff] [blame] | 109 | long n; |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 110 | |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 111 | if (!getrandom_works) { |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 112 | return 0; |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 113 | } |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 114 | |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 115 | flags = blocking ? 0 : GRND_NONBLOCK; |
Victor Stinner | cfb1961 | 2016-06-08 10:16:50 +0200 | [diff] [blame] | 116 | dest = buffer; |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 117 | while (0 < size) { |
Jakub KulĂk | 6f9bc72 | 2018-12-31 03:16:40 +0100 | [diff] [blame] | 118 | #if defined(__sun) && defined(__SVR4) |
Victor Stinner | 9d24271 | 2016-04-12 22:28:49 +0200 | [diff] [blame] | 119 | /* Issue #26735: On Solaris, getrandom() is limited to returning up |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 120 | to 1024 bytes. Call it multiple times if more bytes are |
| 121 | requested. */ |
Victor Stinner | 9d24271 | 2016-04-12 22:28:49 +0200 | [diff] [blame] | 122 | n = Py_MIN(size, 1024); |
| 123 | #else |
Victor Stinner | ec721f3 | 2016-06-16 23:53:47 +0200 | [diff] [blame] | 124 | n = Py_MIN(size, LONG_MAX); |
Victor Stinner | 9d24271 | 2016-04-12 22:28:49 +0200 | [diff] [blame] | 125 | #endif |
Victor Stinner | 79b74ae | 2015-03-30 11:16:40 +0200 | [diff] [blame] | 126 | |
Victor Stinner | 9d24271 | 2016-04-12 22:28:49 +0200 | [diff] [blame] | 127 | errno = 0; |
Victor Stinner | bae2d62 | 2015-10-01 09:47:30 +0200 | [diff] [blame] | 128 | #ifdef HAVE_GETRANDOM |
| 129 | if (raise) { |
| 130 | Py_BEGIN_ALLOW_THREADS |
Victor Stinner | cfb1961 | 2016-06-08 10:16:50 +0200 | [diff] [blame] | 131 | n = getrandom(dest, n, flags); |
Victor Stinner | bae2d62 | 2015-10-01 09:47:30 +0200 | [diff] [blame] | 132 | Py_END_ALLOW_THREADS |
| 133 | } |
| 134 | else { |
Victor Stinner | cfb1961 | 2016-06-08 10:16:50 +0200 | [diff] [blame] | 135 | n = getrandom(dest, n, flags); |
Victor Stinner | bae2d62 | 2015-10-01 09:47:30 +0200 | [diff] [blame] | 136 | } |
| 137 | #else |
| 138 | /* On Linux, use the syscall() function because the GNU libc doesn't |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 139 | expose the Linux getrandom() syscall yet. See: |
| 140 | https://sourceware.org/bugzilla/show_bug.cgi?id=17252 */ |
Victor Stinner | 79b74ae | 2015-03-30 11:16:40 +0200 | [diff] [blame] | 141 | if (raise) { |
| 142 | Py_BEGIN_ALLOW_THREADS |
Victor Stinner | cfb1961 | 2016-06-08 10:16:50 +0200 | [diff] [blame] | 143 | n = syscall(SYS_getrandom, dest, n, flags); |
Victor Stinner | 79b74ae | 2015-03-30 11:16:40 +0200 | [diff] [blame] | 144 | Py_END_ALLOW_THREADS |
| 145 | } |
| 146 | else { |
Victor Stinner | cfb1961 | 2016-06-08 10:16:50 +0200 | [diff] [blame] | 147 | n = syscall(SYS_getrandom, dest, n, flags); |
Victor Stinner | 79b74ae | 2015-03-30 11:16:40 +0200 | [diff] [blame] | 148 | } |
Gregory P. Smith | 3015fb8 | 2018-11-12 22:01:22 -0800 | [diff] [blame] | 149 | # ifdef _Py_MEMORY_SANITIZER |
Gregory P. Smith | 1584a00 | 2018-11-12 12:07:14 -0800 | [diff] [blame] | 150 | if (n > 0) { |
| 151 | __msan_unpoison(dest, n); |
| 152 | } |
| 153 | # endif |
Victor Stinner | bae2d62 | 2015-10-01 09:47:30 +0200 | [diff] [blame] | 154 | #endif |
Victor Stinner | 79b74ae | 2015-03-30 11:16:40 +0200 | [diff] [blame] | 155 | |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 156 | if (n < 0) { |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 157 | /* ENOSYS: the syscall is not supported by the kernel. |
| 158 | EPERM: the syscall is blocked by a security policy (ex: SECCOMP) |
| 159 | or something else. */ |
Victor Stinner | 6d8bc46 | 2016-09-20 22:46:02 +0200 | [diff] [blame] | 160 | if (errno == ENOSYS || errno == EPERM) { |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 161 | getrandom_works = 0; |
| 162 | return 0; |
| 163 | } |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 164 | |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 165 | /* getrandom(GRND_NONBLOCK) fails with EAGAIN if the system urandom |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 166 | is not initialiazed yet. For _PyRandom_Init(), we ignore the |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 167 | error and fall back on reading /dev/urandom which never blocks, |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 168 | even if the system urandom is not initialized yet: |
| 169 | see the PEP 524. */ |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 170 | if (errno == EAGAIN && !raise && !blocking) { |
Victor Stinner | dddf484 | 2016-06-07 11:21:42 +0200 | [diff] [blame] | 171 | return 0; |
| 172 | } |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 173 | |
| 174 | if (errno == EINTR) { |
Victor Stinner | cecdd96 | 2016-08-16 15:19:09 +0200 | [diff] [blame] | 175 | if (raise) { |
| 176 | if (PyErr_CheckSignals()) { |
| 177 | return -1; |
| 178 | } |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 179 | } |
Victor Stinner | cecdd96 | 2016-08-16 15:19:09 +0200 | [diff] [blame] | 180 | |
| 181 | /* retry getrandom() if it was interrupted by a signal */ |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 182 | continue; |
| 183 | } |
| 184 | |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 185 | if (raise) { |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 186 | PyErr_SetFromErrno(PyExc_OSError); |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 187 | } |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 188 | return -1; |
| 189 | } |
| 190 | |
Victor Stinner | cfb1961 | 2016-06-08 10:16:50 +0200 | [diff] [blame] | 191 | dest += n; |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 192 | size -= n; |
| 193 | } |
| 194 | return 1; |
| 195 | } |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 196 | |
| 197 | #elif defined(HAVE_GETENTROPY) |
| 198 | #define PY_GETENTROPY 1 |
| 199 | |
Victor Stinner | de2f1ea | 2017-01-06 11:33:18 +0100 | [diff] [blame] | 200 | /* Fill buffer with size pseudo-random bytes generated by getentropy(): |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 201 | |
Victor Stinner | de2f1ea | 2017-01-06 11:33:18 +0100 | [diff] [blame] | 202 | - Return 1 on success |
| 203 | - Return 0 if getentropy() syscall is not available (failed with ENOSYS or |
| 204 | EPERM). |
| 205 | - Raise an exception (if raise is non-zero) and return -1 on error: |
| 206 | if getentropy() failed with EINTR, raise is non-zero and the Python signal |
| 207 | handler raised an exception, or if getentropy() failed with a different |
| 208 | error. |
| 209 | |
| 210 | getentropy() is retried if it failed with EINTR: interrupted by a signal. */ |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 211 | static int |
| 212 | py_getentropy(char *buffer, Py_ssize_t size, int raise) |
| 213 | { |
Victor Stinner | de2f1ea | 2017-01-06 11:33:18 +0100 | [diff] [blame] | 214 | /* Is getentropy() supported by the running kernel? Set to 0 if |
| 215 | getentropy() failed with ENOSYS or EPERM. */ |
| 216 | static int getentropy_works = 1; |
| 217 | |
| 218 | if (!getentropy_works) { |
| 219 | return 0; |
| 220 | } |
| 221 | |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 222 | while (size > 0) { |
Victor Stinner | de2f1ea | 2017-01-06 11:33:18 +0100 | [diff] [blame] | 223 | /* getentropy() is limited to returning up to 256 bytes. Call it |
| 224 | multiple times if more bytes are requested. */ |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 225 | Py_ssize_t len = Py_MIN(size, 256); |
| 226 | int res; |
| 227 | |
| 228 | if (raise) { |
| 229 | Py_BEGIN_ALLOW_THREADS |
| 230 | res = getentropy(buffer, len); |
| 231 | Py_END_ALLOW_THREADS |
| 232 | } |
| 233 | else { |
| 234 | res = getentropy(buffer, len); |
| 235 | } |
| 236 | |
| 237 | if (res < 0) { |
Victor Stinner | de2f1ea | 2017-01-06 11:33:18 +0100 | [diff] [blame] | 238 | /* ENOSYS: the syscall is not supported by the running kernel. |
| 239 | EPERM: the syscall is blocked by a security policy (ex: SECCOMP) |
| 240 | or something else. */ |
| 241 | if (errno == ENOSYS || errno == EPERM) { |
| 242 | getentropy_works = 0; |
| 243 | return 0; |
| 244 | } |
| 245 | |
| 246 | if (errno == EINTR) { |
| 247 | if (raise) { |
| 248 | if (PyErr_CheckSignals()) { |
| 249 | return -1; |
| 250 | } |
| 251 | } |
| 252 | |
| 253 | /* retry getentropy() if it was interrupted by a signal */ |
| 254 | continue; |
| 255 | } |
| 256 | |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 257 | if (raise) { |
| 258 | PyErr_SetFromErrno(PyExc_OSError); |
| 259 | } |
| 260 | return -1; |
| 261 | } |
| 262 | |
| 263 | buffer += len; |
| 264 | size -= len; |
| 265 | } |
| 266 | return 1; |
| 267 | } |
Jakub KulĂk | 6f9bc72 | 2018-12-31 03:16:40 +0100 | [diff] [blame] | 268 | #endif /* defined(HAVE_GETENTROPY) && !(defined(__sun) && defined(__SVR4)) */ |
Victor Stinner | dcdb60e | 2017-01-06 11:16:20 +0100 | [diff] [blame] | 269 | |
Victor Stinner | 59f7fb2 | 2015-03-18 14:39:33 +0100 | [diff] [blame] | 270 | |
Antoine Pitrou | e472aea | 2014-04-26 14:33:03 +0200 | [diff] [blame] | 271 | static struct { |
| 272 | int fd; |
| 273 | dev_t st_dev; |
| 274 | ino_t st_ino; |
| 275 | } urandom_cache = { -1 }; |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 276 | |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 277 | /* Read random bytes from the /dev/urandom device: |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 278 | |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 279 | - Return 0 on success |
| 280 | - Raise an exception (if raise is non-zero) and return -1 on error |
| 281 | |
| 282 | Possible causes of errors: |
| 283 | |
| 284 | - open() failed with ENOENT, ENXIO, ENODEV, EACCES: the /dev/urandom device |
| 285 | was not found. For example, it was removed manually or not exposed in a |
| 286 | chroot or container. |
| 287 | - open() failed with a different error |
| 288 | - fstat() failed |
| 289 | - read() failed or returned 0 |
| 290 | |
| 291 | read() is retried if it failed with EINTR: interrupted by a signal. |
| 292 | |
| 293 | The file descriptor of the device is kept open between calls to avoid using |
| 294 | many file descriptors when run in parallel from multiple threads: |
| 295 | see the issue #18756. |
| 296 | |
| 297 | st_dev and st_ino fields of the file descriptor (from fstat()) are cached to |
| 298 | check if the file descriptor was replaced by a different file (which is |
| 299 | likely a bug in the application): see the issue #21207. |
| 300 | |
| 301 | If the file descriptor was closed or replaced, open a new file descriptor |
| 302 | but don't close the old file descriptor: it probably points to something |
| 303 | important for some third-party code. */ |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 304 | static int |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 305 | dev_urandom(char *buffer, Py_ssize_t size, int raise) |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 306 | { |
| 307 | int fd; |
| 308 | Py_ssize_t n; |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 309 | |
| 310 | if (raise) { |
| 311 | struct _Py_stat_struct st; |
Nir Soffer | 4484f9d | 2018-03-12 01:39:22 +0200 | [diff] [blame] | 312 | int fstat_result; |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 313 | |
Antoine Pitrou | e472aea | 2014-04-26 14:33:03 +0200 | [diff] [blame] | 314 | if (urandom_cache.fd >= 0) { |
Nir Soffer | 4484f9d | 2018-03-12 01:39:22 +0200 | [diff] [blame] | 315 | Py_BEGIN_ALLOW_THREADS |
| 316 | fstat_result = _Py_fstat_noraise(urandom_cache.fd, &st); |
| 317 | Py_END_ALLOW_THREADS |
| 318 | |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 319 | /* Does the fd point to the same thing as before? (issue #21207) */ |
Nir Soffer | 4484f9d | 2018-03-12 01:39:22 +0200 | [diff] [blame] | 320 | if (fstat_result |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 321 | || st.st_dev != urandom_cache.st_dev |
| 322 | || st.st_ino != urandom_cache.st_ino) { |
| 323 | /* Something changed: forget the cached fd (but don't close it, |
| 324 | since it probably points to something important for some |
| 325 | third-party code). */ |
| 326 | urandom_cache.fd = -1; |
| 327 | } |
Antoine Pitrou | 4879a96 | 2013-08-31 00:26:02 +0200 | [diff] [blame] | 328 | } |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 329 | if (urandom_cache.fd >= 0) |
| 330 | fd = urandom_cache.fd; |
Antoine Pitrou | e472aea | 2014-04-26 14:33:03 +0200 | [diff] [blame] | 331 | else { |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 332 | fd = _Py_open("/dev/urandom", O_RDONLY); |
| 333 | if (fd < 0) { |
| 334 | if (errno == ENOENT || errno == ENXIO || |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 335 | errno == ENODEV || errno == EACCES) { |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 336 | PyErr_SetString(PyExc_NotImplementedError, |
| 337 | "/dev/urandom (or equivalent) not found"); |
Victor Stinner | b27df6f | 2017-01-06 11:39:15 +0100 | [diff] [blame] | 338 | } |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 339 | /* otherwise, keep the OSError exception raised by _Py_open() */ |
Antoine Pitrou | e472aea | 2014-04-26 14:33:03 +0200 | [diff] [blame] | 340 | return -1; |
| 341 | } |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 342 | if (urandom_cache.fd >= 0) { |
| 343 | /* urandom_fd was initialized by another thread while we were |
| 344 | not holding the GIL, keep it. */ |
| 345 | close(fd); |
| 346 | fd = urandom_cache.fd; |
| 347 | } |
Antoine Pitrou | e472aea | 2014-04-26 14:33:03 +0200 | [diff] [blame] | 348 | else { |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 349 | if (_Py_fstat(fd, &st)) { |
| 350 | close(fd); |
| 351 | return -1; |
| 352 | } |
| 353 | else { |
| 354 | urandom_cache.fd = fd; |
| 355 | urandom_cache.st_dev = st.st_dev; |
| 356 | urandom_cache.st_ino = st.st_ino; |
| 357 | } |
Antoine Pitrou | e472aea | 2014-04-26 14:33:03 +0200 | [diff] [blame] | 358 | } |
| 359 | } |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 360 | |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 361 | do { |
| 362 | n = _Py_read(fd, buffer, (size_t)size); |
| 363 | if (n == -1) |
| 364 | return -1; |
| 365 | if (n == 0) { |
| 366 | PyErr_Format(PyExc_RuntimeError, |
| 367 | "Failed to read %zi bytes from /dev/urandom", |
| 368 | size); |
| 369 | return -1; |
| 370 | } |
| 371 | |
| 372 | buffer += n; |
| 373 | size -= n; |
| 374 | } while (0 < size); |
| 375 | } |
| 376 | else { |
| 377 | fd = _Py_open_noraise("/dev/urandom", O_RDONLY); |
| 378 | if (fd < 0) { |
Victor Stinner | c9382eb | 2015-03-19 23:36:33 +0100 | [diff] [blame] | 379 | return -1; |
| 380 | } |
| 381 | |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 382 | while (0 < size) |
| 383 | { |
| 384 | do { |
| 385 | n = read(fd, buffer, (size_t)size); |
| 386 | } while (n < 0 && errno == EINTR); |
Victor Stinner | c9382eb | 2015-03-19 23:36:33 +0100 | [diff] [blame] | 387 | |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 388 | if (n <= 0) { |
| 389 | /* stop on error or if read(size) returned 0 */ |
Victor Stinner | 3ee933f | 2016-08-16 18:27:44 +0200 | [diff] [blame] | 390 | close(fd); |
Victor Stinner | 6974cf2 | 2016-08-16 18:46:38 +0200 | [diff] [blame] | 391 | return -1; |
| 392 | } |
| 393 | |
| 394 | buffer += n; |
| 395 | size -= n; |
| 396 | } |
| 397 | close(fd); |
| 398 | } |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 399 | return 0; |
| 400 | } |
Antoine Pitrou | 4879a96 | 2013-08-31 00:26:02 +0200 | [diff] [blame] | 401 | |
| 402 | static void |
| 403 | dev_urandom_close(void) |
| 404 | { |
Antoine Pitrou | e472aea | 2014-04-26 14:33:03 +0200 | [diff] [blame] | 405 | if (urandom_cache.fd >= 0) { |
| 406 | close(urandom_cache.fd); |
| 407 | urandom_cache.fd = -1; |
Antoine Pitrou | 4879a96 | 2013-08-31 00:26:02 +0200 | [diff] [blame] | 408 | } |
| 409 | } |
Victor Stinner | dcdb60e | 2017-01-06 11:16:20 +0100 | [diff] [blame] | 410 | #endif /* !MS_WINDOWS */ |
Antoine Pitrou | 4879a96 | 2013-08-31 00:26:02 +0200 | [diff] [blame] | 411 | |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 412 | |
| 413 | /* Fill buffer with pseudo-random bytes generated by a linear congruent |
| 414 | generator (LCG): |
| 415 | |
| 416 | x(n+1) = (x(n) * 214013 + 2531011) % 2^32 |
| 417 | |
| 418 | Use bits 23..16 of x(n) to generate a byte. */ |
| 419 | static void |
| 420 | lcg_urandom(unsigned int x0, unsigned char *buffer, size_t size) |
| 421 | { |
| 422 | size_t index; |
| 423 | unsigned int x; |
| 424 | |
| 425 | x = x0; |
| 426 | for (index=0; index < size; index++) { |
| 427 | x *= 214013; |
| 428 | x += 2531011; |
| 429 | /* modulo 2 ^ (8 * sizeof(int)) */ |
| 430 | buffer[index] = (x >> 16) & 0xff; |
| 431 | } |
| 432 | } |
| 433 | |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 434 | /* Read random bytes: |
| 435 | |
| 436 | - Return 0 on success |
| 437 | - Raise an exception (if raise is non-zero) and return -1 on error |
| 438 | |
| 439 | Used sources of entropy ordered by preference, preferred source first: |
| 440 | |
| 441 | - CryptGenRandom() on Windows |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 442 | - getrandom() function (ex: Linux and Solaris): call py_getrandom() |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 443 | - getentropy() function (ex: OpenBSD): call py_getentropy() |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 444 | - /dev/urandom device |
| 445 | |
| 446 | Read from the /dev/urandom device if getrandom() or getentropy() function |
| 447 | is not available or does not work. |
| 448 | |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 449 | Prefer getrandom() over getentropy() because getrandom() supports blocking |
| 450 | and non-blocking mode: see the PEP 524. Python requires non-blocking RNG at |
| 451 | startup to initialize its hash secret, but os.urandom() must block until the |
| 452 | system urandom is initialized (at least on Linux 3.17 and newer). |
| 453 | |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 454 | Prefer getrandom() and getentropy() over reading directly /dev/urandom |
| 455 | because these functions don't need file descriptors and so avoid ENFILE or |
| 456 | EMFILE errors (too many open files): see the issue #18756. |
| 457 | |
| 458 | Only the getrandom() function supports non-blocking mode. |
| 459 | |
| 460 | Only use RNG running in the kernel. They are more secure because it is |
| 461 | harder to get the internal state of a RNG running in the kernel land than a |
| 462 | RNG running in the user land. The kernel has a direct access to the hardware |
| 463 | and has access to hardware RNG, they are used as entropy sources. |
| 464 | |
| 465 | Note: the OpenSSL RAND_pseudo_bytes() function does not automatically reseed |
| 466 | its RNG on fork(), two child processes (with the same pid) generate the same |
| 467 | random numbers: see issue #18747. Kernel RNGs don't have this issue, |
| 468 | they have access to good quality entropy sources. |
| 469 | |
| 470 | If raise is zero: |
| 471 | |
| 472 | - Don't raise an exception on error |
| 473 | - Don't call the Python signal handler (don't call PyErr_CheckSignals()) if |
| 474 | a function fails with EINTR: retry directly the interrupted function |
| 475 | - Don't release the GIL to call functions. |
| 476 | */ |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 477 | static int |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 478 | pyurandom(void *buffer, Py_ssize_t size, int blocking, int raise) |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 479 | { |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 480 | #if defined(PY_GETRANDOM) || defined(PY_GETENTROPY) |
| 481 | int res; |
| 482 | #endif |
| 483 | |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 484 | if (size < 0) { |
| 485 | if (raise) { |
| 486 | PyErr_Format(PyExc_ValueError, |
| 487 | "negative argument not allowed"); |
| 488 | } |
| 489 | return -1; |
| 490 | } |
| 491 | |
| 492 | if (size == 0) { |
| 493 | return 0; |
| 494 | } |
| 495 | |
| 496 | #ifdef MS_WINDOWS |
| 497 | return win32_urandom((unsigned char *)buffer, size, raise); |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 498 | #else |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 499 | |
| 500 | #if defined(PY_GETRANDOM) || defined(PY_GETENTROPY) |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 501 | #ifdef PY_GETRANDOM |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 502 | res = py_getrandom(buffer, size, blocking, raise); |
Victor Stinner | 2f79643 | 2017-01-06 11:26:01 +0100 | [diff] [blame] | 503 | #else |
| 504 | res = py_getentropy(buffer, size, raise); |
Victor Stinner | a49a207 | 2017-01-06 11:17:52 +0100 | [diff] [blame] | 505 | #endif |
| 506 | if (res < 0) { |
| 507 | return -1; |
| 508 | } |
| 509 | if (res == 1) { |
| 510 | return 0; |
| 511 | } |
| 512 | /* getrandom() or getentropy() function is not available: failed with |
| 513 | ENOSYS or EPERM. Fall back on reading from /dev/urandom. */ |
| 514 | #endif |
| 515 | |
| 516 | return dev_urandom(buffer, size, raise); |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 517 | #endif |
| 518 | } |
| 519 | |
Georg Brandl | c6a2c9b | 2013-10-06 18:43:19 +0200 | [diff] [blame] | 520 | /* Fill buffer with size pseudo-random bytes from the operating system random |
Serhiy Storchaka | 56a6d85 | 2014-12-01 18:28:43 +0200 | [diff] [blame] | 521 | number generator (RNG). It is suitable for most cryptographic purposes |
Georg Brandl | c6a2c9b | 2013-10-06 18:43:19 +0200 | [diff] [blame] | 522 | except long living private keys for asymmetric encryption. |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 523 | |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 524 | On Linux 3.17 and newer, the getrandom() syscall is used in blocking mode: |
| 525 | block until the system urandom entropy pool is initialized (128 bits are |
| 526 | collected by the kernel). |
| 527 | |
| 528 | Return 0 on success. Raise an exception and return -1 on error. */ |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 529 | int |
| 530 | _PyOS_URandom(void *buffer, Py_ssize_t size) |
| 531 | { |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 532 | return pyurandom(buffer, size, 1, 1); |
| 533 | } |
| 534 | |
| 535 | /* Fill buffer with size pseudo-random bytes from the operating system random |
| 536 | number generator (RNG). It is not suitable for cryptographic purpose. |
| 537 | |
| 538 | On Linux 3.17 and newer (when getrandom() syscall is used), if the system |
| 539 | urandom is not initialized yet, the function returns "weak" entropy read |
| 540 | from /dev/urandom. |
| 541 | |
| 542 | Return 0 on success. Raise an exception and return -1 on error. */ |
| 543 | int |
| 544 | _PyOS_URandomNonblock(void *buffer, Py_ssize_t size) |
| 545 | { |
| 546 | return pyurandom(buffer, size, 0, 1); |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 547 | } |
| 548 | |
Victor Stinner | 358e5e1 | 2017-12-15 00:51:22 +0100 | [diff] [blame] | 549 | |
| 550 | _PyInitError |
| 551 | _Py_HashRandomization_Init(const _PyCoreConfig *config) |
Eric Snow | 6b4be19 | 2017-05-22 21:36:03 -0700 | [diff] [blame] | 552 | { |
| 553 | void *secret = &_Py_HashSecret; |
| 554 | Py_ssize_t secret_size = sizeof(_Py_HashSecret_t); |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 555 | |
Victor Stinner | f7e5b56 | 2017-11-15 15:48:08 -0800 | [diff] [blame] | 556 | if (_Py_HashSecret_Initialized) { |
| 557 | return _Py_INIT_OK(); |
| 558 | } |
Benjamin Peterson | 69e9727 | 2012-02-21 11:08:50 -0500 | [diff] [blame] | 559 | _Py_HashSecret_Initialized = 1; |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 560 | |
Victor Stinner | 358e5e1 | 2017-12-15 00:51:22 +0100 | [diff] [blame] | 561 | if (config->use_hash_seed) { |
| 562 | if (config->hash_seed == 0) { |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 563 | /* disable the randomized hash */ |
| 564 | memset(secret, 0, secret_size); |
| 565 | } |
| 566 | else { |
Eric Snow | 6b4be19 | 2017-05-22 21:36:03 -0700 | [diff] [blame] | 567 | /* use the specified hash seed */ |
Victor Stinner | 358e5e1 | 2017-12-15 00:51:22 +0100 | [diff] [blame] | 568 | lcg_urandom(config->hash_seed, secret, secret_size); |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 569 | } |
| 570 | } |
| 571 | else { |
Eric Snow | 6b4be19 | 2017-05-22 21:36:03 -0700 | [diff] [blame] | 572 | /* use a random hash seed */ |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 573 | int res; |
| 574 | |
| 575 | /* _PyRandom_Init() is called very early in the Python initialization |
Victor Stinner | e66987e | 2016-09-06 16:33:52 -0700 | [diff] [blame] | 576 | and so exceptions cannot be used (use raise=0). |
| 577 | |
| 578 | _PyRandom_Init() must not block Python initialization: call |
| 579 | pyurandom() is non-blocking mode (blocking=0): see the PEP 524. */ |
| 580 | res = pyurandom(secret, secret_size, 0, 0); |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 581 | if (res < 0) { |
Victor Stinner | db71975 | 2019-05-01 05:35:33 +0200 | [diff] [blame] | 582 | return _Py_INIT_ERR("failed to get random numbers " |
| 583 | "to initialize Python"); |
Victor Stinner | 4bad3b6 | 2016-08-16 15:23:58 +0200 | [diff] [blame] | 584 | } |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 585 | } |
Victor Stinner | f7e5b56 | 2017-11-15 15:48:08 -0800 | [diff] [blame] | 586 | return _Py_INIT_OK(); |
Georg Brandl | 2daf6ae | 2012-02-20 19:54:16 +0100 | [diff] [blame] | 587 | } |
Antoine Pitrou | 4879a96 | 2013-08-31 00:26:02 +0200 | [diff] [blame] | 588 | |
Eric Snow | 6b4be19 | 2017-05-22 21:36:03 -0700 | [diff] [blame] | 589 | |
| 590 | void |
| 591 | _Py_HashRandomization_Fini(void) |
Antoine Pitrou | 4879a96 | 2013-08-31 00:26:02 +0200 | [diff] [blame] | 592 | { |
Victor Stinner | d50c3f3 | 2014-05-02 22:06:44 +0200 | [diff] [blame] | 593 | #ifdef MS_WINDOWS |
| 594 | if (hCryptProv) { |
Tim Golden | b8ac3e1 | 2014-05-06 13:29:45 +0100 | [diff] [blame] | 595 | CryptReleaseContext(hCryptProv, 0); |
Victor Stinner | d50c3f3 | 2014-05-02 22:06:44 +0200 | [diff] [blame] | 596 | hCryptProv = 0; |
| 597 | } |
| 598 | #else |
Antoine Pitrou | 4879a96 | 2013-08-31 00:26:02 +0200 | [diff] [blame] | 599 | dev_urandom_close(); |
| 600 | #endif |
| 601 | } |