Subject: Re: [PATCH v2 net-next] net: ipv6: Add sysctl entry to disable MTU updates from RA

From: Daniel Borkmann <[email-masked]>
Date: Tue, 20 Jan 2015 00:01:04 +0100

On 01/19/2015 10:36 PM, Harout Hedeshian wrote:
...
> diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
> index 85b0221..da50faa 100644
> --- a/Documentation/networking/ip-sysctl.txt
> +++ b/Documentation/networking/ip-sysctl.txt
> @@ -1287,6 +1287,13 @@ accept_ra_rtr_pref - BOOLEAN
>   	Functional default: enabled if accept_ra is enabled.
>   			    disabled if accept_ra is disabled.
>
> +accept_ra_mtu - BOOLEAN
> +	Apply the MTU value specified in RA option 5 (RFC4861). If
> +	disabled, the MTU specified in the RA will be ignored.
> +
> +	Functional default: enabled if accept_ra is enabled.
> +                            disabled if accept_ra is disabled.

Nit: please indent correctly with tab here.

> +
...
> diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
> index 73cb02d..437a6a4 100644
> --- a/include/uapi/linux/ipv6.h
> +++ b/include/uapi/linux/ipv6.h
> @@ -169,6 +169,7 @@ enum {
>   	DEVCONF_SUPPRESS_FRAG_NDISC,
>   	DEVCONF_ACCEPT_RA_FROM_LOCAL,
>   	DEVCONF_USE_OPTIMISTIC,
> +	DEVCONF_ACCEPT_RA_MTU,
>   	DEVCONF_MAX
>   };

You also need a corresponding ipv6_store_devconf() entry, otherwise
netlink dumps will always see this setting as disabled.