netdev - Re: [PATCH V2 net-next 3/3] ipv6: add ip6_flowlabel

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Date:	Wed, 15 Jan 2014 23:49:38 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Florent Fourcot <florent.fourcot@...t-bretagne.fr>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH V2 net-next 3/3] ipv6: add ip6_flowlabel_consistency sysctl

On Wed, Jan 15, 2014 at 12:30:03PM +0100, Florent Fourcot wrote:
> With the introduction of IPV6_FL_F_REFLECT, there is no guarantee of
> flow label unicity. This patch introduces a new sysctl to protect the old
> behaviour, enable by default.
> 
> Changelog of the V2:
> 	* Remove useless hunk in sysctl_binary.c
> 	* Rebase on net-next

Seems still to generate conflicts on my branch. :/

The conflicts are simple to clean up, but if you decide to rebase, please
check the patches with ./scripts/checkpatch --strict and eliminate all those
small nitpicks.

> Signed-off-by: Florent Fourcot <florent.fourcot@...t-bretagne.fr>
> ---
>  Documentation/networking/ip-sysctl.txt | 8 ++++++++
>  include/net/netns/ipv6.h               | 1 +
>  net/ipv6/af_inet6.c                    | 1 +
>  net/ipv6/ip6_flowlabel.c               | 7 +++++++
>  net/ipv6/sysctl_net_ipv6.c             | 8 ++++++++
>  5 files changed, 25 insertions(+)
> 
> diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
> index c97932c..7453640 100644
> --- a/Documentation/networking/ip-sysctl.txt
> +++ b/Documentation/networking/ip-sysctl.txt
> @@ -1118,6 +1118,14 @@ bindv6only - BOOLEAN
>  
>  	Default: FALSE (as specified in RFC3493)
>  
> +ip6_flowlabel_consistency - BOOLEAN
> +	Protect the consistency (and unicity) of flow label.
> +	You have to disable it to use IPV6_FL_F_REFLECT flag on the
> +	flow label manager.
> +	TRUE: enabled
> +	FALSE: disabled
> +	Default: TRUE
> +
>  anycast_src_echo_reply - BOOLEAN
>  	Controls the use of anycast addresses as source addresses for ICMPv6
>  	echo reply
> diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
> index 76fc7d1..3cc291b 100644
> --- a/include/net/netns/ipv6.h
> +++ b/include/net/netns/ipv6.h
> @@ -27,6 +27,7 @@ struct netns_sysctl_ipv6 {
>  	int ip6_rt_gc_elasticity;
>  	int ip6_rt_mtu_expires;
>  	int ip6_rt_min_advmss;
> +	int ip6_flowlabel_consistency;
>  	int icmpv6_time;
>  };
>  
> diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
> index c921d5d..943c796 100644
> --- a/net/ipv6/af_inet6.c
> +++ b/net/ipv6/af_inet6.c
> @@ -775,6 +775,7 @@ static int __net_init inet6_net_init(struct net *net)
>  
>  	net->ipv6.sysctl.bindv6only = 0;
>  	net->ipv6.sysctl.icmpv6_time = 1*HZ;
> +	net->ipv6.sysctl.ip6_flowlabel_consistency = 1;
>  	atomic_set(&net->ipv6.rt_genid, 0);
>  
>  	err = ipv6_init_mibs(net);
> diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
> index 2c0f9dc..85f0453 100644
> --- a/net/ipv6/ip6_flowlabel.c
> +++ b/net/ipv6/ip6_flowlabel.c
> @@ -587,8 +587,15 @@ int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
>  
>  	case IPV6_FL_A_GET:
>  		if (freq.flr_flags & IPV6_FL_F_REFLECT) {
> +			struct net *net = sock_net(sk);
> +			if (net->ipv6.sysctl.ip6_flowlabel_consistency) {
> +				pr_info("Can not set IPV6_FL_F_REFLECT if ip6_flowlabel_consistency sysctl is enable \n");

Maybe we should do rate-limiting here, so a user cannot spam kmsg.

> +				return -EPERM;
> +			}
> +
>  			if (sk->sk_protocol != IPPROTO_TCP)
>  				return -ENOPROTOOPT;
> +
>  			np->repflow = 1;
>  			return 0;
>  		}
> diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
> index 6b6a2c8..8c99cf0 100644
> --- a/net/ipv6/sysctl_net_ipv6.c
> +++ b/net/ipv6/sysctl_net_ipv6.c
> @@ -31,6 +31,13 @@ static struct ctl_table ipv6_table_template[] = {
>  		.mode		= 0644,
>  		.proc_handler	= proc_dointvec
>  	},
> +	{
> +		.procname	= "ip6_flowlabel_consistency",
> +		.data		= &init_net.ipv6.sysctl.ip6_flowlabel_consistency,
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		.proc_handler	= proc_dointvec
> +	},
>  	{ }
>  };
>  
> @@ -59,6 +66,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
>  		goto out;
>  	ipv6_table[0].data = &net->ipv6.sysctl.bindv6only;
>  	ipv6_table[1].data = &net->ipv6.anycast_src_echo_reply;
> +	ipv6_table[2].data = &net->ipv6.sysctl.ip6_flowlabel_consistency;
>  
>  	ipv6_route_table = ipv6_route_sysctl_init(net);
>  	if (!ipv6_route_table)

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