On Mon, Mar 19, 2018 at 10:31:07AM +0000, Carlo Caione wrote:
> 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@xxxxxxxxxxxx>
> ---
> 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;
Applied, but not sure if I like the if-EAGAIN-break there. It will
break in all situations and completely bypass the lose_counter idea.
Maybe it would be better to accept that we will call getrandom() 16x
on systems with uninitialized entropy. (And maybe add xusleep() to the
loop...)
Karel
> else if (lose_counter++ > 16) /* entropy problem? */
> break;
> }
> --
> 2.14.1
>
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--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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