From bae2d6203fca3ecaaf9fbc7cee84ad83ddf52dc5 Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Thu, 1 Oct 2015 09:47:30 +0200 Subject: [PATCH] Issue #25003: On Solaris 11.3 or newer, os.urandom() now uses the getrandom() function instead of the getentropy() function. The getentropy() function is blocking to generate very good quality entropy, os.urandom() doesn't need such high-quality entropy. --- Lib/test/test_os.py | 16 ++++++++------- Misc/NEWS | 5 +++++ Python/random.c | 49 +++++++++++++++++++++++++++++++-------------- configure | 43 ++++++++++++++++++++++++++++++++++++--- configure.ac | 31 +++++++++++++++++++++++++--- pyconfig.h.in | 3 +++ 6 files changed, 119 insertions(+), 28 deletions(-) diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py index bb717cc6614186..da5a130d6c6851 100644 --- a/Lib/test/test_os.py +++ b/Lib/test/test_os.py @@ -1226,13 +1226,15 @@ def test_urandom_subprocess(self): self.assertNotEqual(data1, data2) -HAVE_GETENTROPY = (sysconfig.get_config_var('HAVE_GETENTROPY') == 1) -HAVE_GETRANDOM = (sysconfig.get_config_var('HAVE_GETRANDOM_SYSCALL') == 1) - -@unittest.skipIf(HAVE_GETENTROPY, - "getentropy() does not use a file descriptor") -@unittest.skipIf(HAVE_GETRANDOM, - "getrandom() does not use a file descriptor") +# os.urandom() doesn't use a file descriptor when it is implemented with the +# getentropy() function, the getrandom() function or the getrandom() syscall +OS_URANDOM_DONT_USE_FD = ( + sysconfig.get_config_var('HAVE_GETENTROPY') == 1 + or sysconfig.get_config_var('HAVE_GETRANDOM') == 1 + or sysconfig.get_config_var('HAVE_GETRANDOM_SYSCALL') == 1) + +@unittest.skipIf(OS_URANDOM_DONT_USE_FD , + "os.random() does not use a file descriptor") class URandomFDTests(unittest.TestCase): @unittest.skipUnless(resource, "test requires the resource module") def test_urandom_failure(self): diff --git a/Misc/NEWS b/Misc/NEWS index 55f4e40d6c456f..bde08658e2818c 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -11,6 +11,11 @@ Release date: TBA Core and Builtins ----------------- +- Issue #25003: On Solaris 11.3 or newer, os.urandom() now uses the + getrandom() function instead of the getentropy() function. The getentropy() + function is blocking to generate very good quality entropy, os.urandom() + doesn't need such high-quality entropy. + - Issue #25182: The stdprinter (used as sys.stderr before the io module is imported at startup) now uses the backslashreplace error handler. diff --git a/Python/random.c b/Python/random.c index ea09e84a7b0d73..1d57b1b6621cb4 100644 --- a/Python/random.c +++ b/Python/random.c @@ -6,7 +6,9 @@ # ifdef HAVE_SYS_STAT_H # include # endif -# ifdef HAVE_GETRANDOM_SYSCALL +# ifdef HAVE_GETRANDOM +# include +# elif defined(HAVE_GETRANDOM_SYSCALL) # include # endif #endif @@ -70,7 +72,9 @@ win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise) return 0; } -#elif HAVE_GETENTROPY +#elif defined(HAVE_GETENTROPY) && !defined(sun) +#define PY_GETENTROPY 1 + /* Fill buffer with size pseudo-random bytes generated by getentropy(). Return 0 on success, or raise an exception and return -1 on error. @@ -105,16 +109,19 @@ py_getentropy(unsigned char *buffer, Py_ssize_t size, int fatal) return 0; } -#else /* !HAVE_GETENTROPY */ +#else + +#if defined(HAVE_GETRANDOM) || defined(HAVE_GETRANDOM_SYSCALL) +#define PY_GETRANDOM 1 -#ifdef HAVE_GETRANDOM_SYSCALL 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 later */ + /* Is getrandom() supported by the running kernel? + * Need Linux kernel 3.17 or newer, or Solaris 11.3 or newer */ static int getrandom_works = 1; - /* Use /dev/urandom, block if the kernel has no entropy */ + /* Use non-blocking /dev/urandom device. On Linux at boot, the getrandom() + * syscall blocks until /dev/urandom is initialized with enough entropy. */ const int flags = 0; int n; @@ -124,7 +131,18 @@ py_getrandom(void *buffer, Py_ssize_t size, int raise) while (0 < size) { errno = 0; - /* Use syscall() because the libc doesn't expose getrandom() yet, see: +#ifdef HAVE_GETRANDOM + if (raise) { + Py_BEGIN_ALLOW_THREADS + n = getrandom(buffer, size, flags); + Py_END_ALLOW_THREADS + } + else { + n = getrandom(buffer, size, 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 @@ -134,6 +152,7 @@ py_getrandom(void *buffer, Py_ssize_t size, int raise) else { n = syscall(SYS_getrandom, buffer, size, flags); } +#endif if (n < 0) { if (errno == ENOSYS) { @@ -182,7 +201,7 @@ dev_urandom_noraise(unsigned char *buffer, Py_ssize_t size) assert (0 < size); -#ifdef HAVE_GETRANDOM_SYSCALL +#ifdef PY_GETRANDOM if (py_getrandom(buffer, size, 0) == 1) return; /* getrandom() is not supported by the running kernel, fall back @@ -218,14 +237,14 @@ dev_urandom_python(char *buffer, Py_ssize_t size) int fd; Py_ssize_t n; struct _Py_stat_struct st; -#ifdef HAVE_GETRANDOM_SYSCALL +#ifdef PY_GETRANDOM int res; #endif if (size <= 0) return 0; -#ifdef HAVE_GETRANDOM_SYSCALL +#ifdef PY_GETRANDOM res = py_getrandom(buffer, size, 1); if (res < 0) return -1; @@ -304,7 +323,7 @@ dev_urandom_close(void) } } -#endif /* HAVE_GETENTROPY */ +#endif /* Fill buffer with pseudo-random bytes generated by a linear congruent generator (LCG): @@ -345,7 +364,7 @@ _PyOS_URandom(void *buffer, Py_ssize_t size) #ifdef MS_WINDOWS return win32_urandom((unsigned char *)buffer, size, 1); -#elif HAVE_GETENTROPY +#elif defined(PY_GETENTROPY) return py_getentropy(buffer, size, 0); #else return dev_urandom_python((char*)buffer, size); @@ -392,7 +411,7 @@ _PyRandom_Init(void) else { #ifdef MS_WINDOWS (void)win32_urandom(secret, secret_size, 0); -#elif HAVE_GETENTROPY +#elif defined(PY_GETENTROPY) (void)py_getentropy(secret, secret_size, 1); #else dev_urandom_noraise(secret, secret_size); @@ -408,7 +427,7 @@ _PyRandom_Fini(void) CryptReleaseContext(hCryptProv, 0); hCryptProv = 0; } -#elif HAVE_GETENTROPY +#elif defined(PY_GETENTROPY) /* nothing to clean */ #else dev_urandom_close(); diff --git a/configure b/configure index 06b4d582e09119..398f12160fc8cb 100755 --- a/configure +++ b/configure @@ -16085,11 +16085,11 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext #include int main() { - const int flags = 0; char buffer[1]; - int n; + const size_t buflen = sizeof(buffer); + const int flags = 0; /* ignore the result, Python checks for ENOSYS at runtime */ - (void)syscall(SYS_getrandom, buffer, sizeof(buffer), flags); + (void)syscall(SYS_getrandom, buffer, buflen, flags); return 0; } @@ -16111,6 +16111,43 @@ $as_echo "#define HAVE_GETRANDOM_SYSCALL 1" >>confdefs.h fi +# check if the getrandom() function is available +# the test was written for the Solaris function of +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for the getrandom() function" >&5 +$as_echo_n "checking for the getrandom() function... " >&6; } +cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ + + + #include + + int main() { + char buffer[1]; + const size_t buflen = sizeof(buffer); + const int flags = 0; + /* ignore the result, Python checks for ENOSYS at runtime */ + (void)getrandom(buffer, buflen, flags); + return 0; + } + + +_ACEOF +if ac_fn_c_try_link "$LINENO"; then : + have_getrandom=yes +else + have_getrandom=no +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext conftest.$ac_ext +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_getrandom" >&5 +$as_echo "$have_getrandom" >&6; } + +if test "$have_getrandom" = yes; then + +$as_echo "#define HAVE_GETRANDOM 1" >>confdefs.h + +fi + # generate output files ac_config_files="$ac_config_files Makefile.pre Modules/Setup.config Misc/python.pc Misc/python-config.sh" diff --git a/configure.ac b/configure.ac index 792f580c12ac9f..694293e8be83f2 100644 --- a/configure.ac +++ b/configure.ac @@ -5154,11 +5154,11 @@ AC_LINK_IFELSE( #include int main() { - const int flags = 0; char buffer[1]; - int n; + const size_t buflen = sizeof(buffer); + const int flags = 0; /* ignore the result, Python checks for ENOSYS at runtime */ - (void)syscall(SYS_getrandom, buffer, sizeof(buffer), flags); + (void)syscall(SYS_getrandom, buffer, buflen, flags); return 0; } ]]) @@ -5170,6 +5170,31 @@ if test "$have_getrandom_syscall" = yes; then [Define to 1 if the Linux getrandom() syscall is available]) fi +# check if the getrandom() function is available +# the test was written for the Solaris function of +AC_MSG_CHECKING(for the getrandom() function) +AC_LINK_IFELSE( +[ + AC_LANG_SOURCE([[ + #include + + int main() { + char buffer[1]; + const size_t buflen = sizeof(buffer); + const int flags = 0; + /* ignore the result, Python checks for ENOSYS at runtime */ + (void)getrandom(buffer, buflen, flags); + return 0; + } + ]]) +],[have_getrandom=yes],[have_getrandom=no]) +AC_MSG_RESULT($have_getrandom) + +if test "$have_getrandom" = yes; then + AC_DEFINE(HAVE_GETRANDOM, 1, + [Define to 1 if the getrandom() function is available]) +fi + # generate output files AC_CONFIG_FILES(Makefile.pre Modules/Setup.config Misc/python.pc Misc/python-config.sh) AC_CONFIG_FILES([Modules/ld_so_aix], [chmod +x Modules/ld_so_aix]) diff --git a/pyconfig.h.in b/pyconfig.h.in index 0d40c94cd4c0a3..b0cafb318574c9 100644 --- a/pyconfig.h.in +++ b/pyconfig.h.in @@ -395,6 +395,9 @@ /* Define to 1 if you have the `getpwent' function. */ #undef HAVE_GETPWENT +/* Define to 1 if the getrandom() function is available */ +#undef HAVE_GETRANDOM + /* Define to 1 if the Linux getrandom() syscall is available */ #undef HAVE_GETRANDOM_SYSCALL