python: Don't use getentropy on Linux

Backport a patch from 2.7 branch to fix a regression with glibc
2.24 causing "OSError: [Errno 38] Function not implemented" when
calling urandom() with older kernels.

Signed-off-by: Andreas Oberritter <obi@opendreambox.org>
Signed-off-by: Ross Burton <ross.burton@intel.com>

2 files changed, 42 insertions, 0 deletions

diff --git a/meta/recipes-devtools/python/python/Don-t-use-getentropy-on-Linux.patch b/meta/recipes-devtools/python/python/Don-t-use-getentropy-on-Linux.patch
new file mode 100644
index 0000000000..38e53778dc
--- /dev/null
+++ b/meta/recipes-devtools/python/python/Don-t-use-getentropy-on-Linux.patch
@@ -0,0 +1,41 @@
+Upstream-Status: Backport
+
+Signed-off-by: Andreas Oberritter <obi@opendreambox.org>
+
+From 905d1b30ac7cb0e31c57cec0533825c8f170b942 Mon Sep 17 00:00:00 2001
+From: Victor Stinner <victor.stinner@gmail.com>
+Date: Mon, 9 Jan 2017 11:10:41 +0100
+Subject: [PATCH] Don't use getentropy() on Linux
+
+Issue #29188: Support glibc 2.24 on Linux: don't use getentropy() function but
+read from /dev/urandom to get random bytes, for example in os.urandom().  On
+Linux, getentropy() is implemented which getrandom() is blocking mode, whereas
+os.urandom() should not block.
+
+(cherry picked from commit 2687486756721e39164fa9f597e468c35d495227)
+---
+ Python/random.c | 11 +++++++++--
+ 1 file changed, 9 insertions(+), 2 deletions(-)
+
+diff --git a/Python/random.c b/Python/random.c
+index b4bc1f3..f3f5d14 100644
+--- a/Python/random.c
++++ b/Python/random.c
+@@ -94,8 +94,15 @@ win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise)
+ }
+ 
+ /* Issue #25003: Don't use getentropy() on Solaris (available since
+- * Solaris 11.3), it is blocking whereas os.urandom() should not block. */
+-#elif defined(HAVE_GETENTROPY) && !defined(sun)
++   Solaris 11.3), it is blocking whereas os.urandom() should not block.
++
++   Issue #29188: Don't use getentropy() on Linux since the glibc 2.24
++   implements it with the getrandom() syscall which can fail with ENOSYS,
++   and this error is not supported in py_getentropy() and getrandom() is called
++   with flags=0 which blocks until system urandom is initialized, which is not
++   the desired behaviour to seed the Python hash secret nor for os.urandom():
++   see the PEP 524 which was only implemented in Python 3.6. */
++#elif defined(HAVE_GETENTROPY) && !defined(sun) && !defined(linux)
+ #define PY_GETENTROPY 1
+ 
+ /* Fill buffer with size pseudo-random bytes generated by getentropy().
diff --git a/meta/recipes-devtools/python/python_2.7.12.bb b/meta/recipes-devtools/python/python_2.7.12.bb
index 9fe35db2de..2c6a3194a2 100644
--- a/meta/recipes-devtools/python/python_2.7.12.bb
+++ b/meta/recipes-devtools/python/python_2.7.12.bb
@@ -27,6 +27,7 @@ SRC_URI += "\
   file://use_sysroot_ncurses_instead_of_host.patch \
   file://add-CROSSPYTHONPATH-for-PYTHON_FOR_BUILD.patch \
   file://python-fix-CVE-2016-1000110.patch \
+  file://Don-t-use-getentropy-on-Linux.patch \
 "
 
 S = "${WORKDIR}/Python-${PV}"