The patch description and the code are clearly saying that STP is an exception, but I am just worried about the users. Maybe a proper description in the iptables help is sufficient.
Users may otherwise try to use this new hook for STP too (for example to generate logs or produce statistics/counters or divert STP traffic to userspace, etc). Out of curiosity, ... if this gets accepted, shouldn't you provide NF_BR_LINK_LOCAL_OUT too? Or maybe you should call it NF_BR_LINK_LOCAL_FWD instead of NF_BR_LINK_LOCAL_IN? /Chris > -----Original Message----- > From: netfilter-devel-ow...@vger.kernel.org [mailto:netfilter-devel- > ow...@vger.kernel.org] On Behalf Of Stephen Hemminger > Sent: Friday, August 19, 2011 1:58 PM > To: David Lamparter > Cc: Nick Carter; Ed Swierk; net...@vger.kernel.org; bridge@linux- > foundation.org; netfilter-de...@vger.kernel.org > Subject: [RFC] bridge: add netfilter hook for forwarding 802.1D group > addresses > > The IEEE standard expects that link local multicast packets will not > be forwarded by a bridge. But there are cases like 802.1X which may > require that packets be forwarded. For maximum flexibilty implement > this via netfilter. > > The netfilter chain is slightly different from other chains in that > if packet is ACCEPTED by the chain, it means it should be forwarded. > And if the packet verdict result is DROP, the packet is processed > as a local packet. The default result for this chain is DROP and > therefore users who do not install any rules will get the same > result as before; ie. packets are only processed on the local host > and not forwarded. > > Spanning Tree Packets are treated specially and do not > go through the new chain. > > This code is conceptual design concept only. It compiles but > hasn't been tested. > > Signed-off-by: Stephen Hemminger <shemmin...@vyatta.com> > > --- > include/linux/netfilter_bridge.h | 5 ++++- > net/bridge/br_input.c | 15 ++++++++++++--- > net/bridge/netfilter/ebtable_filter.c | 18 ++++++++++++++++-- > 3 files changed, 32 insertions(+), 6 deletions(-) > > --- a/include/linux/netfilter_bridge.h 2011-08-19 13:11:51.972125670 > -0700 > +++ b/include/linux/netfilter_bridge.h 2011-08-19 13:13:36.452130443 > -0700 > @@ -22,7 +22,10 @@ > #define NF_BR_POST_ROUTING 4 > /* Not really a hook, but used for the ebtables broute table */ > #define NF_BR_BROUTING 5 > -#define NF_BR_NUMHOOKS 6 > +/* Packets to link local multicast addresses (01-80-C2-00-00-XX) */ > +#define NF_BR_LINK_LOCAL_IN 6 > + > +#define NF_BR_NUMHOOKS 7 > > #ifdef __KERNEL__ > > --- a/net/bridge/br_input.c 2011-08-18 16:12:02.576672548 -0700 > +++ b/net/bridge/br_input.c 2011-08-19 13:28:13.696170518 -0700 > @@ -166,10 +166,19 @@ rx_handler_result_t br_handle_frame(stru > if (skb->protocol == htons(ETH_P_PAUSE)) > goto drop; > > - /* If STP is turned off, then forward */ > - if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0) > - goto forward; > + /* If this is Spanning Tree Protocol packet */ > + if (dest[5] == 0) { > + /* and STP is turned off, then forward */ > + if (p->br->stp_enabled == BR_NO_STP) > + goto forward; > + } > + /* Hook to allow forwarding other group MAC addresses */ > + else if (p->state == BR_STATE_FORWARDING && > + NF_HOOK(NFPROTO_BRIDGE, NF_BR_LINK_LOCAL_IN, skb, > skb->dev, > + NULL, br_handle_frame_finish)) > + return RX_HANDLER_CONSUMED; /* forwarded */ > > + /* Packet will go only to the local host. */ > if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, > NULL, br_handle_local_finish)) { > return RX_HANDLER_CONSUMED; /* consumed by filter */ > --- a/net/bridge/netfilter/ebtable_filter.c 2011-08-19 > 13:14:46.232133631 -0700 > +++ b/net/bridge/netfilter/ebtable_filter.c 2011-08-19 > 13:27:33.436168679 -0700 > @@ -11,8 +11,10 @@ > #include <linux/netfilter_bridge/ebtables.h> > #include <linux/module.h> > > -#define FILTER_VALID_HOOKS ((1 << NF_BR_LOCAL_IN) | (1 << > NF_BR_FORWARD) | \ > - (1 << NF_BR_LOCAL_OUT)) > +#define FILTER_VALID_HOOKS ((1 << NF_BR_LOCAL_IN) | \ > + (1 << NF_BR_FORWARD) | \ > + (1 << NF_BR_LOCAL_OUT) | \ > + (1 << NF_BR_LINK_LOCAL_IN)) > > static struct ebt_entries initial_chains[] = > { > @@ -28,6 +30,10 @@ static struct ebt_entries initial_chains > .name = "OUTPUT", > .policy = EBT_ACCEPT, > }, > + { > + .name = "LINKLOCAL", > + .policy = EBT_DROP, > + }, > }; > > static struct ebt_replace_kernel initial_table = > @@ -39,6 +45,7 @@ static struct ebt_replace_kernel initial > [NF_BR_LOCAL_IN] = &initial_chains[0], > [NF_BR_FORWARD] = &initial_chains[1], > [NF_BR_LOCAL_OUT] = &initial_chains[2], > + [NF_BR_LINK_LOCAL_IN] = &initial_chains[3], > }, > .entries = (char *)initial_chains, > }; > @@ -95,6 +102,13 @@ static struct nf_hook_ops ebt_ops_filter > .hooknum = NF_BR_LOCAL_OUT, > .priority = NF_BR_PRI_FILTER_OTHER, > }, > + { > + .hook = ebt_in_hook, > + .owner = THIS_MODULE, > + .pf = NFPROTO_BRIDGE, > + .hooknum = NF_BR_LINK_LOCAL_IN, > + .priority = NF_BR_PRI_FILTER_BRIDGED, > + }, > }; > > static int __net_init frame_filter_net_init(struct net *net) > -- > To unsubscribe from this list: send the line "unsubscribe netfilter- > devel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html _______________________________________________ Bridge mailing list Bridge@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/bridge
