On Tue, Nov 27, 2018 at 01:20:47AM +0100, Pablo Neira Ayuso wrote:
> Hi,
>
> On Wed, Nov 07, 2018 at 02:48:58PM +0100, Christian Brauner wrote:
> [...]
> > diff --git a/include/net/netns/netfilter.h b/include/net/netns/netfilter.h
> > index ca043342c0eb..eedbd1ac940e 100644
> > --- a/include/net/netns/netfilter.h
> > +++ b/include/net/netns/netfilter.h
> > @@ -35,4 +35,20 @@ struct netns_nf {
> > bool defrag_ipv6;
> > #endif
> > };
> > +
> > +struct netns_brnf {
> > +#ifdef CONFIG_SYSCTL
> > + struct ctl_table_header *ctl_hdr;
> > +#endif
> > +
> > + /* default value is 1 */
> > + int call_iptables;
> > + int call_ip6tables;
> > + int call_arptables;
> > +
> > + /* default value is 0 */
> > + int filter_vlan_tagged;
> > + int filter_pppoe_tagged;
> > + int pass_vlan_indev;
> > +};
>
> I have spun on this several times, wondering if there's a way to avoid
> scratching these many bytes per netns to expose these sysctl entries
> that are plain on/off toggles... You said this:
>
> >Currently, the /proc/sys/net/bridge folder is only created in the
> >initial network namespace
>
> I think we can add one single sysctl to expose these as flags from net
> namespaces. Idea is to keep the existing (legacy) sysctl entries for
> init_net only, and add a new single new one that exposes these as flags
> (should be also available for consistency in init_net I'd suggest).
> Flags could be map in this way, eg.
>
> 0x1 call_iptables
> 0x2 call_ip6tables
> 0x4 call_arptables
> 0x8 filter_vlan_tagged
> ...
>
> Also documentation would be good to have for this.
>
> Would this idea fly for you? Thanks.
My suggestion is to keep these files per network namespace but have a
single flag argument in struct netns_brnf:
+struct netns_brnf {
+#ifdef CONFIG_SYSCTL
+ struct ctl_table_header *ctl_hdr;
+#endif
+
+ /* default value is 1 */
+ unsigned int filter_flags;
+};
#define BRNF_CALL_IPTABLES 0x1
#define BRNF_CALL_IP6TABLES 0x2
#define BRNF_CALL_ARPTABLES 0x4
#define BRNF_CALL_VLAN_TAGGED 0x8
a write to the corresponding file would then cause the flag to be set or
unset in filter_flags.
This way we are a) space-efficient internally not bloating struct net
while b) not breaking running tools in non-initial network namespaces
that expect the files to be there. b) is really the important bit here. :)
Christian
