[Buildroot] [PATCH] package/rng-tools: make jitterentropy conditional

[Matthew Weber]

Thomas,


On Wed, Feb 5, 2020 at 2:46 PM Matthew Weber
<matthew.weber at rockwellcollins.com> wrote:
>
> Thomas,
>
> On Wed, Feb 5, 2020 at 1:33 PM Thomas Petazzoni
> <thomas.petazzoni at bootlin.com> wrote:
> >
> > On Wed,  5 Feb 2020 12:26:08 -0600
> > Matt Weber <matthew.weber at rockwellcollins.com> wrote:
> >
> > > The update of rng-tools from 5 to 6.7 introduced a change where
> > > the jitterentropy library was enabled by default instead of
> > > returning a special 66 return code to hangle the case of no
> > > hwrng. This patch reverts that change and allows a user to
> > > select when to enable the jitterentropy source. The bug
> > > documents an issue of when a hwrng is enabled with jitterentropy
> > > there is a longer boot time.
> >
> > I don't understand this story of the 66 return code. Could you explain
> > a bit more ?
>
> In Buildroot commit 22cb51e1 the systemd support addition included the
> successcode change based on the Fedora bugfix for ignoring if no hwrng
> is present (https://bugzilla.redhat.com/show_bug.cgi?id=892178).

Ryan Barnett noticed that rng-tools dropped the special return code.
I guess we could just drop support for this special case as well....
https://github.com/nhorman/rng-tools/blob/v6.8/rngd.c#L805

>
> >
> > > index 11386d1e5d..c0bcffe59e 100644
> > > --- a/package/rng-tools/rngd.service
> > > +++ b/package/rng-tools/rngd.service
> > > @@ -3,6 +3,7 @@ Description=Hardware RNG Entropy Gatherer Daemon
> > >
> > >  [Service]
> > >  ExecStart=/usr/sbin/rngd -f $DAEMON_ARGS
> > > +SuccessExitStatus=66
> >
> > Will this work even if jitterentropy support is enabled ?
>
> My understanding is that you'd never hit this return case when
> jitterentropy support built in as it would always init the entropy
> pool using that library as a source.  Thus the problem of the boot
> delay even when hwrng is present.
>
> Matt



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