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changeset: 103972:ddc54f08bdfa branch: 3.5 user: Victor Stinner victor.stinner@gmail.com date: Tue Sep 20 22:46:02 2016 +0200 files: Misc/NEWS Python/random.c description: 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. diff -r 41e9e711b9b5 -r ddc54f08bdfa Misc/NEWS --- a/Misc/NEWS Tue Sep 20 22:26:18 2016 +0200 +++ b/Misc/NEWS Tue Sep 20 22:46:02 2016 +0200 @@ -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 -r 41e9e711b9b5 -r ddc54f08bdfa Python/random.c --- a/Python/random.c Tue Sep 20 22:26:18 2016 +0200 +++ b/Python/random.c Tue Sep 20 22:46:02 2016 +0200 @@ -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 /victor.stinner@gmail.com