Re: [PATCH net-next] ipv6: don't generate link-local addr in random or privacy mode

[Rocco Yue <rocco.yue@mediatek.com>]

On Tue, 2021-11-09 at 14:55 +0800, Rocco Yue wrote:
> In the 3GPP TS 29.061, here is a description as follows:
> "In order to avoid any conflict between the link-local address
> of the MS and that of the GGSN, the Interface-Identifier used by
> the MS to build its link-local address shall be assigned by the
> GGSN. The GGSN ensures the uniqueness of this Interface-Identifier.
> The MT shall then enforce the use of this Interface-Identifier by
> the TE"
> 
> In other words, in the cellular network, GGSN determines whether
> to reply a solicited RA message by identifying the bottom 64 bits
> of the source address of the received RS message. Therefore,
> cellular network device's ipv6 link-local address should be set
> as the format of fe80::(GGSN assigned IID).
> 
> To meet the above spec requirement, this patch adds two new
> addr_gen_mode:
> 
> 1) IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA, this mode is suitable
> for cellular networks that support RFC7217. In this mode, the
> kernel doesn't generate a link-local address for the cellular
> NIC, and generates an ipv6 stable privacy global address after
> receiving the RA message.
> 
> 2) IN6_ADDR_GEN_MODE_RANDOM_NO_LLA, in this mode, the kernel
> doesn't generate a link-local address for the cellular NIC,
> and will use the bottom 64 bits of the link-local address(same
> as the IID assigned by GGSN) to form an ipv6 global address
> after receiveing the RA message.
> 
> Signed-off-by: Rocco Yue <rocco.yue@mediatek.com>
> ---
>  include/uapi/linux/if_link.h       |  2 ++
>  net/ipv6/addrconf.c                | 22 ++++++++++++++++------
>  tools/include/uapi/linux/if_link.h |  2 ++
>  3 files changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/include/uapi/linux/if_link.h
> b/include/uapi/linux/if_link.h
> index eebd3894fe89..9c5695744c7d 100644
> --- a/include/uapi/linux/if_link.h
> +++ b/include/uapi/linux/if_link.h
> @@ -428,6 +428,8 @@ enum in6_addr_gen_mode {
>  	IN6_ADDR_GEN_MODE_NONE,
>  	IN6_ADDR_GEN_MODE_STABLE_PRIVACY,
>  	IN6_ADDR_GEN_MODE_RANDOM,
> +	IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA,
> +	IN6_ADDR_GEN_MODE_RANDOM_NO_LLA,
>  };
>  
>  /* Bridge section */
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index 3445f8017430..0045de10f4b5 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -392,7 +392,8 @@ static struct inet6_dev *ipv6_add_dev(struct
> net_device *dev)
>  	timer_setup(&ndev->rs_timer, addrconf_rs_timer, 0);
>  	memcpy(&ndev->cnf, dev_net(dev)->ipv6.devconf_dflt,
> sizeof(ndev->cnf));
>  
> -	if (ndev->cnf.stable_secret.initialized)
> +	if (ndev->cnf.stable_secret.initialized &&
> +	    ndev->cnf.addr_gen_mode !=
> IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA)
>  		ndev->cnf.addr_gen_mode =
> IN6_ADDR_GEN_MODE_STABLE_PRIVACY;
>  
>  	ndev->cnf.mtu6 = dev->mtu;
> @@ -2578,7 +2579,8 @@ static void manage_tempaddrs(struct inet6_dev
> *idev,
>  static bool is_addr_mode_generate_stable(struct inet6_dev *idev)
>  {
>  	return idev->cnf.addr_gen_mode ==
> IN6_ADDR_GEN_MODE_STABLE_PRIVACY ||
> -	       idev->cnf.addr_gen_mode == IN6_ADDR_GEN_MODE_RANDOM;
> +	       idev->cnf.addr_gen_mode == IN6_ADDR_GEN_MODE_RANDOM ||
> +	       idev->cnf.addr_gen_mode ==
> IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA;
>  }
>  
>  int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device
> *dev,
> @@ -3331,6 +3333,8 @@ static void addrconf_addr_gen(struct inet6_dev
> *idev, bool prefix_route)
>  					      0, 0, GFP_KERNEL);
>  		break;
>  	case IN6_ADDR_GEN_MODE_NONE:
> +	case IN6_ADDR_GEN_MODE_RANDOM_NO_LLA:
> +	case IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA:
>  	default:
>  		/* will not add any link local address */
>  		break;
> @@ -5798,7 +5802,9 @@ static int check_addr_gen_mode(int mode)
>  	if (mode != IN6_ADDR_GEN_MODE_EUI64 &&
>  	    mode != IN6_ADDR_GEN_MODE_NONE &&
>  	    mode != IN6_ADDR_GEN_MODE_STABLE_PRIVACY &&
> -	    mode != IN6_ADDR_GEN_MODE_RANDOM)
> +	    mode != IN6_ADDR_GEN_MODE_RANDOM &&
> +	    mode != IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA &&
> +	    mode != IN6_ADDR_GEN_MODE_RANDOM_NO_LLA)
>  		return -EINVAL;
>  	return 1;
>  }
> @@ -6428,15 +6434,19 @@ static int
> addrconf_sysctl_stable_secret(struct ctl_table *ctl, int write,
>  		for_each_netdev(net, dev) {
>  			struct inet6_dev *idev = __in6_dev_get(dev);
>  
> -			if (idev) {
> +			if (idev && idev->cnf.addr_gen_mode !=
> +			    IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA) {
>  				idev->cnf.addr_gen_mode =
>  					IN6_ADDR_GEN_MODE_STABLE_PRIVAC
> Y;
>  			}
>  		}
>  	} else {
>  		struct inet6_dev *idev = ctl->extra1;
> -
> -		idev->cnf.addr_gen_mode =
> IN6_ADDR_GEN_MODE_STABLE_PRIVACY;
> +		if (idev->cnf.addr_gen_mode !=
> +		    IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA) {
> +			idev->cnf.addr_gen_mode =
> +				IN6_ADDR_GEN_MODE_STABLE_PRIVACY;
> +		}
>  	}
>  
>  out:
> diff --git a/tools/include/uapi/linux/if_link.h
> b/tools/include/uapi/linux/if_link.h
> index b3610fdd1fee..fb69137aea89 100644
> --- a/tools/include/uapi/linux/if_link.h
> +++ b/tools/include/uapi/linux/if_link.h
> @@ -241,6 +241,8 @@ enum in6_addr_gen_mode {
>  	IN6_ADDR_GEN_MODE_NONE,
>  	IN6_ADDR_GEN_MODE_STABLE_PRIVACY,
>  	IN6_ADDR_GEN_MODE_RANDOM,
> +	IN6_ADDR_GEN_MODE_STABLE_PRIVACY_NO_LLA,
> +	IN6_ADDR_GEN_MODE_RANDOM_NO_LLA,
>  };
>  
>  /* Bridge section */
> -- 
> 2.18.0
> 

Gentle ping on this patch. :-)

Thanks,

Rocco