[Python-checkins] cpython (3.5): Catch EPERM error in py_getrandom()

Tue Sep 20 16:52:41 EDT 2016

https://hg.python.org/cpython/rev/ddc54f08bdfa
changeset: 103972:ddc54f08bdfa
branch: 3.5
user: Victor Stinner <victor.stinner at gmail.com>
date: Tue Sep 20 22:46:02 2016 +0200
summary:
 Catch EPERM error in py_getrandom()
Issue #27955: Fallback on reading /dev/urandom device when the getrandom()
syscall fails with EPERM, for example when blocked by SECCOMP.
files:
 Misc/NEWS | 3 +++
 Python/random.c | 15 ++++++++-------
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #27955: Fallback on reading /dev/urandom device when the getrandom()
+ syscall fails with EPERM, for example when blocked by SECCOMP.
+
 - Issue #28131: Fix a regression in zipimport's compile_source(). zipimport
 should use the same optimization level as the interpreter.
 
diff --git a/Python/random.c b/Python/random.c
--- a/Python/random.c
+++ b/Python/random.c
@@ -121,8 +121,8 @@
 
 /* Call getrandom()
 - Return 1 on success
- - Return 0 if getrandom() syscall is not available (failed with ENOSYS)
- or if getrandom(GRND_NONBLOCK) failed with EAGAIN (system urandom
+ - Return 0 if getrandom() syscall is not available (failed with ENOSYS or
+ EPERM) or if getrandom(GRND_NONBLOCK) failed with EAGAIN (system urandom
 not initialized yet) and raise=0.
 - Raise an exception (if raise is non-zero) and return -1 on error:
 getrandom() failed with EINTR and the Python signal handler raised an
@@ -131,7 +131,7 @@
 py_getrandom(void *buffer, Py_ssize_t size, int raise)
 {
 /* Is getrandom() supported by the running kernel? Set to 0 if getrandom()
- failed with ENOSYS. Need Linux kernel 3.17 or newer, or Solaris
+ failed with ENOSYS or EPERM. Need Linux kernel 3.17 or newer, or Solaris
 11.3 or newer */
 static int getrandom_works = 1;
 
@@ -182,8 +182,9 @@
 
 if (n < 0) {
 /* ENOSYS: getrandom() syscall not supported by the kernel (but
- * maybe supported by the host which built Python). */
- if (errno == ENOSYS) {
+ * maybe supported by the host which built Python). EPERM:
+ * getrandom() syscall blocked by SECCOMP or something else. */
+ if (errno == ENOSYS || errno == EPERM) {
 getrandom_works = 0;
 return 0;
 }
@@ -250,7 +251,7 @@
 if (py_getrandom(buffer, size, 0) == 1) {
 return;
 }
- /* getrandom() failed with ENOSYS,
+ /* getrandom() failed with ENOSYS or EPERM,
 fall back on reading /dev/urandom */
 #endif
 
@@ -301,7 +302,7 @@
 if (res == 1) {
 return 0;
 }
- /* getrandom() failed with ENOSYS,
+ /* getrandom() failed with ENOSYS or EPERM,
 fall back on reading /dev/urandom */
 #endif
 
-- 
Repository URL: https://hg.python.org/cpython
