Re: [PATCH iproute2-next] iplink: add support for setting IPv4 devconf parameters

[David Ahern <dsahern@kernel.org>]

On 6/1/26 8:32 AM, Fernando Fernandez Mancera wrote:
> Currently, modifying IPv4 interface configuration parameters requires
> interacting with sysctl (/proc/sys/net/ipv4/conf/*). While
> ip-netconf exists for monitoring these values, there has been no native
> way to set them directly through iproute2.
> 
> This patch introduces the support for that via 'inet' at the 'ip link
> set'. It uses IFLA_INET_CONF netlink attribute to set the parameter.
> 
> Example to enable forwarding on an interface:
> 
> ip link set dev enp8s0 inet forwarding on

If an attribute can be set this way, then ip link show needs to show the
values. What's the plan on that front?

> 
> Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
> ---
>  ip/iplink.c           | 354 ++++++++++++++++++++++++++++++++++++++++++
>  man/man8/ip-link.8.in |  81 ++++++++++
>  2 files changed, 435 insertions(+)
> 

...

>  		"		[ gso_max_size BYTES ] [ gso_ipv4_max_size BYTES ] [ gso_max_segs PACKETS ]\n"
> @@ -551,6 +569,339 @@ static int iplink_parse_vf(int vf, int *argcp, char ***argvp,
>  	return 0;
>  }
>  
> +static int iplink_parse_inet(int *argcp, char ***argvp, struct iplink_req *req)
> +{
> +	struct rtattr *afs, *afinet, *inet_devconf;
> +	char **argv = *argvp;
> +	int argc = *argcp;
> +	int ret;
> +
> +	afs = addattr_nest(&req->n, sizeof(*req), IFLA_AF_SPEC);
> +	afinet = addattr_nest(&req->n, sizeof(*req), AF_INET);
> +	inet_devconf = addattr_nest(&req->n, sizeof(*req), IFLA_INET_CONF);
> +
> +	while (NEXT_ARG_OK()) {
> +		NEXT_ARG();
> +		if (matches(*argv, "forwarding") == 0) {

new uses of matches are not allowed. If s/matches/strcmp/ is the only
comment, I can fix up before applying.