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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.
This commit is contained in:
Victor Stinner 2015-09-18 15:38:37 +02:00
parent 258f17c96d
commit 3abf44e48f
5 changed files with 110 additions and 21 deletions
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5
Misc/NEWS
View File

@ -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.

49
Python/random.c
View File

@ -6,7 +6,9 @@
# ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
# endif
# ifdef HAVE_GETRANDOM_SYSCALL
# ifdef HAVE_GETRANDOM
# include <sys/random.h>
# elif defined(HAVE_GETRANDOM_SYSCALL)
# include <sys/syscall.h>
# 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();

43
configure vendored
View File

@ -16005,11 +16005,11 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
#include <sys/syscall.h>
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 <sys/random.h>
{ $as_echo "$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 <sys/random.h>
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"

31
configure.ac
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@ -5111,11 +5111,11 @@ AC_LINK_IFELSE(
#include <sys/syscall.h>
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 "$have_getrandom_syscall" = yes; then
[Define to 1 if the Linux getrandom() syscall is available])
fi
# check if the getrandom() function is available
# the test was written for the Solaris function of <sys/random.h>
AC_MSG_CHECKING(for the getrandom() function)
AC_LINK_IFELSE(
[
AC_LANG_SOURCE([[
#include <sys/random.h>
int main() {
char buffer[1];
const size_t buflen = sizeof(buffer);
const int flags = 0;
/* ignore the result, Python checks for ENOSYS at runtime */
(void)getrandom(buffer, buflen, flags);
return 0;
}
]])
],[have_getrandom=yes],[have_getrandom=no])
AC_MSG_RESULT($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])

3
pyconfig.h.in
View File

@ -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