| From a9cf659e0508c1f56813a7d74c64f67bbc962538 Mon Sep 17 00:00:00 2001 |
| From: Carlo Caione <carlo@endlessm.com> |
| Date: Mon, 19 Mar 2018 10:31:07 +0000 |
| Subject: [PATCH] lib/randutils: Do not block on getrandom() |
| |
| In Endless we have hit a problem when using 'sfdisk' on the really first |
| boot to automatically expand the rootfs partition. On this platform |
| 'sfdisk' is blocking on getrandom() because not enough random bytes are |
| available. This is an ARM platform without a hwrng. |
| |
| We fix this passing GRND_NONBLOCK to getrandom(). 'sfdisk' will use the |
| best entropy it has available and fallback only as necessary. |
| |
| Signed-off-by: Carlo Caione <carlo@endlessm.com> |
| Signed-off-by: Peter Korsgaard <peter@korsgaard.com> |
| --- |
| lib/randutils.c | 6 +++++- |
| 1 file changed, 5 insertions(+), 1 deletion(-) |
| |
| diff --git a/lib/randutils.c b/lib/randutils.c |
| index e1c4059e1..02c3d9eb0 100644 |
| --- a/lib/randutils.c |
| +++ b/lib/randutils.c |
| @@ -36,6 +36,8 @@ |
| |
| #if !defined(HAVE_GETRANDOM) && defined(SYS_getrandom) |
| /* libc without function, but we have syscal */ |
| +#define GRND_NONBLOCK 0x01 |
| +#define GRND_RANDOM 0x02 |
| static int getrandom(void *buf, size_t buflen, unsigned int flags) |
| { |
| return (syscall(SYS_getrandom, buf, buflen, flags)); |
| @@ -104,13 +106,15 @@ void random_get_bytes(void *buf, size_t nbytes) |
| int x; |
| |
| errno = 0; |
| - x = getrandom(cp, n, 0); |
| + x = getrandom(cp, n, GRND_NONBLOCK); |
| if (x > 0) { /* success */ |
| n -= x; |
| cp += x; |
| lose_counter = 0; |
| } else if (errno == ENOSYS) /* kernel without getrandom() */ |
| break; |
| + else if (errno == EAGAIN) |
| + break; |
| else if (lose_counter++ > 16) /* entropy problem? */ |
| break; |
| } |
| -- |
| 2.11.0 |
| |
