From 3abf44e48f973d5ffba779471a6c4dab00be2f77 Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Fri, 18 Sep 2015 15:38:37 +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. --- Misc/NEWS | 5 +++++ Python/random.c | 49 ++++++++++++++++++++++++++++++++++--------------- configure | 43 ++++++++++++++++++++++++++++++++++++++++--- configure.ac | 31 ++++++++++++++++++++++++++++--- pyconfig.h.in | 3 +++ 5 files changed, 110 insertions(+), 21 deletions(-) diff --git a/Misc/NEWS b/Misc/NEWS index 827d7882860..77efd05f913 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -10,6 +10,11 @@ Release date: XXXX-XX-XX 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 #9232: Modify Python's grammar to allow trailing commas in the argument list of a function declaration. For example, "def f(*, a = 3,): pass" is now legal. Patch from Mark Dickinson. diff --git a/Python/random.c b/Python/random.c index ea09e84a7b0..8f3e6d60219 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 + /* 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 -#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 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 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 PY_GETENTROPY /* nothing to clean */ #else dev_urandom_close(); diff --git a/configure b/configure index 95d953ac3da..f7b1839c193 100755 --- a/configure +++ b/configure @@ -16005,11 +16005,11 @@ 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; } @@ -16031,6 +16031,43 @@ $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 668234d7e2e..180a421f707 100644 --- a/configure.ac +++ b/configure.ac @@ -5111,11 +5111,11 @@ 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; } ]]) @@ -5127,6 +5127,31 @@ 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 0d40c94cd4c..b0cafb31857 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