Re: [PATCH net-next v2] ipv6: Add NETCONFA_FORCE_FORWARDING to netconf messages

[Ido Schimmel <idosch@nvidia.com>]

On Wed, Nov 04, 2026 at 10:46:10AM +0100, Gabriel Goller wrote:
> Since force_forwarding was added, changing the sysctl sends an
> RTM_NEWNETCONF notification of type NETCONFA_FORCE_FORWARDING, but
> inet6_netconf_fill_devconf() never emits the attribute. Listeners only
> receive NETCONFA_IFINDEX without the new value, and RTM_GETNETCONF
> replies and dumps omit it as well.
> 
> Also send a notification when disabling all.forwarding resets
> force_forwarding on an interface, which previously happened silently.
> 
> Fixes: f24987ef6959 ("ipv6: add `force_forwarding` sysctl to enable per-interface forwarding")

Fixes tag on net-next is only valid when the blamed commit is only in
net-next, but maybe Paolo / Jakub will agree to strip it, so wait with
v3.

> Signed-off-by: Gabriel Goller <g.goller@proxmox.com>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>

There's a report from Sashiko [1] about a pre-existing issue:
all.force_forwarding not being cleared when all.forwarding is cleared.

# ip link add name dummy1 type dummy
# sysctl -wq net.ipv6.conf.all.forwarding=1
# sysctl -wq net.ipv6.conf.all.force_forwarding=1
# sysctl -wq net.ipv6.conf.all.forwarding=0
# sysctl net.ipv6.conf.dummy1.force_forwarding
net.ipv6.conf.dummy1.force_forwarding = 0
# sysctl net.ipv6.conf.all.force_forwarding
net.ipv6.conf.all.force_forwarding = 1

[1] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261104-ipv6_add_netconfa-v2-1-6f660990062f@proxmox.com