[Buildroot] [PATCH] package/dropbear: fix when readlink is busybox'

[Yann E. MORIN <yann.morin.1998@free.fr>]

Peter, All,

On 2015-08-24 17:38 +0200, Peter Korsgaard spake thusly:
> >>>>> "Yann" == Yann E MORIN <yann.morin.1998@free.fr> writes:
> 
> Hi,
> 
> >> Looking at the recent changes to S50dropbear, isn't it quite noisy with
>  >> a RO rootfs? I would imagine those rm and mkdir calls complain with
>  >> RO. Perhaps we should add 2>/dev/null to them?
> 
>  > Well, on a RO filesystem, we'd create /var/run/dropbear on each boot,
>  > and thus regenerate keys on each boot. This means keys from such a
>  > device can not really be trusted.
> 
> Well, with a RO filesystem you only have the option to either generate
> at each boot or bake in a hardcoded host key in the rootfs. Neither is
> really great for security.

Or, as some are doing (Paul for example), have /etc/dropbear point to a
R/W location (e.g. a persistent FS done at first boot) and have the
symlink overwritten by an overlay to point to that location.

Which is anyway something sane to do in most case of a R/O FS.

>  > So I'd prefer we get the error messages, as a clue to the user that
>  > something is wrong. Maybe we could have had an explicit message, yes.
> 
> Those fairly obscure messages are imho not really helpful - But on the
> other hand I'm not sure a dedicated message is really warranted.

Maybe something along the lines of;

    I have no persistent location to store SSH host keys.
    I will generate new ones on each boot.
    Are you sure that's what you wanted to do?

Regards,
Yann E. MORIN.

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