Subject: Re: [PATCH 1/1] net namespace: dynamically configure new net namespace inherit net config

From: yzhu1 <[email-masked]>
Date: Fri, 26 Jun 2015 17:50:55 +0800

Hi, all

Some expect the new net namespace inherits from the original net config. 
Some expect the new net namespace
inherits from the current net config, including the modified net 
configurations.

To meet the different reqirements, this patch is made.

I think maybe mainline should need this patch.

Please comment on this patch.

Any reply is appreciated.

Thanks a lot.
Zhu Yanjun
On 06/26/2015 05:37 PM, Zhu Yanjun wrote:
> The new net namespace can inherit from the original net config, or
> the current net config. As such, a config is needed to decide where
> the new namespace inherit from.
>
> Signed-off-by: Zhu Yanjun <[email-masked]>
> ---
>   init/Kconfig       |  9 +++++++++
>   net/ipv4/devinet.c | 13 +++++++++++++
>   2 files changed, 22 insertions(+)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index dc24dec..fab8c41 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1212,6 +1212,15 @@ config NET_NS
>   	  Allow user space to create what appear to be multiple instances
>   	  of the network stack.
>   
> +config NET_NS_INHERIT_ORIGINAL
> +	bool "New network namespace inherits from original net config"
> +	depends on NET_NS
> +	default n
> +	help
> +	  Allow new network namespace inherit from original net config.
> +	  If no, the new network namespace inherits from the current net
> +	  config including the modified net config.
> +
>   endif # NAMESPACES
>   
>   config SCHED_AUTOGROUP
> diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
> index 419d23c..cf635e4 100644
> --- a/net/ipv4/devinet.c
> +++ b/net/ipv4/devinet.c
> @@ -2271,6 +2271,7 @@ static __net_init int devinet_init_net(struct net *net)
>   #endif
>   
>   	err = -ENOMEM;
> +#ifndef CONFIG_NET_NS_INHERIT_ORIGINAL
>   	all = &ipv4_devconf;
>   	dflt = &ipv4_devconf_dflt;
>   
> @@ -2282,6 +2283,15 @@ static __net_init int devinet_init_net(struct net *net)
>   		dflt = kmemdup(dflt, sizeof(ipv4_devconf_dflt), GFP_KERNEL);
>   		if (!dflt)
>   			goto err_alloc_dflt;
> +#else
> +	all = kmemdup(&ipv4_devconf, sizeof(ipv4_devconf), GFP_KERNEL);
> +	if (!all)
> +		goto err_alloc_all;
> +
> +	dflt = kmemdup(&ipv4_devconf_dflt, sizeof(ipv4_devconf_dflt), GFP_KERNEL);
> +	if (!dflt)
> +		goto err_alloc_dflt;
> +#endif
>   
>   #ifdef CONFIG_SYSCTL
>   		tbl = kmemdup(tbl, sizeof(ctl_forward_entry), GFP_KERNEL);
> @@ -2292,7 +2302,10 @@ static __net_init int devinet_init_net(struct net *net)
>   		tbl[0].extra1 = all;
>   		tbl[0].extra2 = net;
>   #endif
> +
> +#ifndef CONFIG_NET_NS_INHERIT_ORIGINAL
>   	}
> +#endif
>   
>   #ifdef CONFIG_SYSCTL
>   	err = __devinet_sysctl_register(net, "all", all);