[PATCH net] ipv6: Add NETCONFA_FORCE_FORWARDING to netconf messages

[PATCH net] ipv6: Add NETCONFA_FORCE_FORWARDING to netconf messages

[Gabriel Goller]

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.

Fixes: f24987ef6959 ("ipv6: add `force_forwarding` sysctl to enable per-interface forwarding")
Signed-off-by: Gabriel Goller <g.goller@proxmox.com>
---
 net/ipv6/addrconf.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index c8c0dd04982d..1b8caf6f4f16 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -529,6 +529,9 @@ static int inet6_netconf_msgsize_devconf(int type)
 	if (all || type == NETCONFA_IGNORE_ROUTES_WITH_LINKDOWN)
 		size += nla_total_size(4);
 
+	if (all || type == NETCONFA_FORCE_FORWARDING)
+		size += nla_total_size(4);
+
 	return size;
 }
 
@@ -578,6 +581,11 @@ static int inet6_netconf_fill_devconf(struct sk_buff *skb, int ifindex,
 			READ_ONCE(devconf->ignore_routes_with_linkdown)) < 0)
 		goto nla_put_failure;
 
+	if ((all || type == NETCONFA_FORCE_FORWARDING) &&
+	    nla_put_s32(skb, NETCONFA_FORCE_FORWARDING,
+			READ_ONCE(devconf->force_forwarding)) < 0)
+		goto nla_put_failure;
+
 out:
 	nlmsg_end(skb, nlh);
 	return 0;

---
base-commit: 734bef548a96e8774d6eef5dfa2026c6edc4e80b
base-tree: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main
change-id: 20261023-ipv6_add_netconfa-b87b66b35272

Best regards,
--  
Gabriel Goller <g.goller@proxmox.com>

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

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.

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

[Gabriel Goller]

On 23.10.2026 11:06, netdev-bot+sinfo@kernel.org wrote:
> Hi!
> 
> This is an automated message. This series looks like a fix, but its
> commit messages seem to be missing some information:
> 
>  - How the issue was discovered, e.g. hit in production, hit during
>    development, syzbot report, manual code inspection, LLM or static
>    analysis tool scan.

Hit during development of ifupdown2.

>  - Whether the issue was actually triggered, or is only theoretical
>    (e.g. found by code inspection). If it was triggered please include
>    the symptoms, like the stack trace or error messages.

Can actually be triggered.
Check with `ip montor netconf` running and execute e.g.
`sysctl -w net.ipv6.conf.<dev>.force_forwarding=1`. The state of the
force_forwarding property is not returned

> Please do not repost the series just to address the above. Instead,
> reply to this email with the missing information, so that reviewers
> can take it into account. If the series needs another revision for
> other reasons, please include the information in the commit messages
> then.
> 
> The evaluation is done by an LLM so it may be wrong, if you think
> that is the case please reply and explain.

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

[Fernando Fernandez Mancera]

On 10/23/26 12:59 PM, 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.
> 
> Fixes: f24987ef6959 ("ipv6: add `force_forwarding` sysctl to enable per-interface forwarding")
> Signed-off-by: Gabriel Goller <g.goller@proxmox.com>

Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>

Thanks!