[OE-core] busybox: udhcpc: fix IPv6 support when using udhcpc

[Stefan Agner]

On 2020-01-20 13:32, Quentin Schulz wrote:
> Hi all,
> 
> On Mon, Jan 13, 2020 at 03:57:31PM +0100, Quentin Schulz wrote:
>> Hi all,
>>
>> On Mon, May 14, 2018 at 04:44:15PM +0200, Stefan Agner wrote:
>> > From: Stefan Agner <stefan.agner at toradex.com>
>> >
>> > The udhcpc script calls ip addr flush .. which flushes addresses
>> > of any address family, including IPv6. However, busybox udhcpc is
>> > IPv4 only and should not influence IPv6 addressing. Hence use ip
>> > addr flush with family constrait.
>> >
>> > The script particularly broke IPv6 SLAAC: Typically when udhcpc
>> > calls the script the kernel already assigned the IPv6 link-local
>> > address. The flush removes the link-local IPv6 address again and
>> > prohibits proper IPv6 operation such as SLAAC since neighbor
>> > discovery protocol relies on IPv6 link-local addressing.
>> >
>> > Signed-off-by: Stefan Agner <stefan.agner at toradex.com>
>> > ---
>> >  meta/recipes-core/busybox/files/simple.script | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/meta/recipes-core/busybox/files/simple.script b/meta/recipes-core/busybox/files/simple.script
>> > index 6ed0293525..8b5eb53633 100644
>> > --- a/meta/recipes-core/busybox/files/simple.script
>> > +++ b/meta/recipes-core/busybox/files/simple.script
>> > @@ -28,7 +28,7 @@ case "$1" in
>> >  		fi
>> >  		if ! root_is_nfs ; then
>> >                          if [ $have_bin_ip -eq 1 ]; then
>> > -                                /SBIN_DIR/ip addr flush dev $interface
>> > +                                /SBIN_DIR/ip -4 addr flush dev $interface
>> >                                  /SBIN_DIR/ip link set dev $interface up
>> >                          else
>> >                                  /SBIN_DIR/ifconfig $interface 0.0.0.0
>>
>> Kindly pinging, happened to us as well many times.
>>
> 
> Kindly pinging.

Just checked, we still override that script in our layer, so definitely
would be happy if this gets merged upstream so I can get rid of our
custom script downstream.

--
Stefan