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Message-ID: <620d3cfbe58e3ae87ef1d5e7f2aa1588cac3e64a.camel@vyatta.att-mail.com>
Date: Wed, 14 Aug 2019 17:40:58 +0100
From: Patrick Ruddy <pruddy@...tta.att-mail.com>
To: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
Ido Schimmel <idosch@...sch.org>
Cc: netdev@...r.kernel.org, roopa@...ulusnetworks.com,
linus.luessing@...3.blue
Subject: Re: [PATCH net-next] mcast: ensure L-L IPv6 packets are accepted by
bridge
Thanks both for the quick replies, answers inline...
On Wed, 2019-08-14 at 02:55 +0300, Nikolay Aleksandrov wrote:
> On 8/13/19 10:53 PM, Ido Schimmel wrote:
> > + Bridge maintainers, Linus
> >
>
> Good catch Ido, thanks!
> First I'd say the subject needs to reflect that this is a bridge change
> better, please rearrange it like so - bridge: mcast: ...
> More below,
>
> > On Tue, Aug 13, 2019 at 03:18:04PM +0100, Patrick Ruddy wrote:
> > > At present only all-nodes IPv6 multicast packets are accepted by
> > > a bridge interface that is not in multicast router mode. Since
> > > other protocols can be running in the absense of multicast
> > > forwarding e.g. OSPFv3 IPv6 ND. Change the test to allow
> > > all of the FFx2::/16 range to be accepted when not in multicast
> > > router mode. This aligns the code with IPv4 link-local reception
> > > and RFC4291
> >
> > Can you please quote the relevant part from RFC 4291?
> >
> > > Signed-off-by: Patrick Ruddy <pruddy@...tta.att-mail.com>
> > > ---
> > > include/net/addrconf.h | 15 +++++++++++++++
> > > net/bridge/br_multicast.c | 2 +-
> > > 2 files changed, 16 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/include/net/addrconf.h b/include/net/addrconf.h
> > > index becdad576859..05b42867e969 100644
> > > --- a/include/net/addrconf.h
> > > +++ b/include/net/addrconf.h
> > > @@ -434,6 +434,21 @@ static inline void addrconf_addr_solict_mult(const struct in6_addr *addr,
> > > htonl(0xFF000000) | addr->s6_addr32[3]);
> > > }
> > >
> > > +/*
> > > + * link local multicast address range ffx2::/16 rfc4291
> > > + */
> > > +static inline bool ipv6_addr_is_ll_mcast(const struct in6_addr *addr)
> > > +{
> > > +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
> > > + __be64 *p = (__be64 *)addr;
> > > + return ((p[0] & cpu_to_be64(0xff0f000000000000UL))
> > > + ^ cpu_to_be64(0xff02000000000000UL)) == 0UL;
> > > +#else
> > > + return ((addr->s6_addr32[0] & htonl(0xff0f0000)) ^
> > > + htonl(0xff020000)) == 0;
> > > +#endif
> > > +}
> > > +
> > > static inline bool ipv6_addr_is_ll_all_nodes(const struct in6_addr *addr)
> > > {
> > > #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
> > > diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> > > index 9b379e110129..ed3957381fa2 100644
> > > --- a/net/bridge/br_multicast.c
> > > +++ b/net/bridge/br_multicast.c
> > > @@ -1664,7 +1664,7 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
> > > err = ipv6_mc_check_mld(skb);
> > >
> > > if (err == -ENOMSG) {
> > > - if (!ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr))
> > > + if (!ipv6_addr_is_ll_mcast(&ipv6_hdr(skb)->daddr))
> > > BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
> >
> > IIUC, you want IPv6 link-local packets to be locally received, but this
> > also changes how these packets are flooded. RFC 4541 says that packets
>
> Indeed, we'll start flooding them all, not just the all hosts address.
> If that is at all required it'll definitely have to be optional.
>
> > addressed to the all hosts address are a special case and should be
> > forwarded to all ports:
> >
> > "In IPv6, the data forwarding rules are more straight forward because MLD is
> > mandated for addresses with scope 2 (link-scope) or greater. The only exception
> > is the address FF02::1 which is the all hosts link-scope address for which MLD
> > messages are never sent. Packets with the all hosts link-scope address should
> > be forwarded on all ports."
> >
>
> I wonder what is the problem for the host to join such group on behalf of the bridge ?
> Then you'll receive the traffic at least locally and the RFC says it itself - MLD is mandated
> for the other link-local addresses.
> It's very late here and maybe I'm missing something.. :)
>
The group is being joined by MLD at the L3 level but the packets are
not being passed up to the l3 interface becasue there is a MLD querier
on the network
snippet from /proc/net/igmp6
...
40 sw1 ff0200000000000000000001ff008700 1 00000004 0
40 sw1 ff020000000000000000000000000002 1 00000004 0
40 sw1 ff020000000000000000000000000001 1 0000000C 0
40 sw1 ff010000000000000000000000000001 1 00000008 0
41 lo1 ff020000000000000000000000000001 1 0000000C 0
41 lo1 ff010000000000000000000000000001 1 00000008 0
42 sw1.1 ff020000000000000000000000000006 1 00000004 0
42 sw1.1 ff020000000000000000000000000005 1 00000004 0
42 sw1.1 ff0200000000000000000001ff000000 2 00000004 0
42 sw1.1 ff0200000000000000000001ff008700 1 00000004 0
42 sw1.1 ff0200000000000000000001ff000099 1 00000004 0
42 sw1.1 ff020000000000000000000000000002 1 00000004 0
42 sw1.1 ff020000000000000000000000000001 1 0000000C 0
42 sw1.1 ff010000000000000000000000000001 1 00000008 0
...
the bridge is sw1 and the l3 intervace is sw1.1
Ido is correct about the flooding - I will update the patch with the
comments and reissue.
Thanks again
-pr
>
> > Maybe you want something like:
> >
>
> I think we can do without the new field, either pass local_rcv into br_multicast_rcv() or
> set it based on return value. The extra test will have to remain unfortunately, but we
> can reduce the tests by one if carefully done.
>
> > diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
> > index 09b1dd8cd853..9f312a73f61c 100644
> > --- a/net/bridge/br_input.c
> > +++ b/net/bridge/br_input.c
> > @@ -132,7 +132,8 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
> > if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
> > br_multicast_querier_exists(br, eth_hdr(skb))) {
> > if ((mdst && mdst->host_joined) ||
> > - br_multicast_is_router(br)) {
> > + br_multicast_is_router(br) ||
> > + BR_INPUT_SKB_CB_LOCAL_RECEIVE(skb)) {
> > local_rcv = true;
> > br->dev->stats.multicast++;
> > }
> > diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> > index 9b379e110129..f03cecf6174e 100644
> > --- a/net/bridge/br_multicast.c
> > +++ b/net/bridge/br_multicast.c
> > @@ -1667,6 +1667,9 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br,
> > if (!ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr))
> > BR_INPUT_SKB_CB(skb)->mrouters_only = 1;
> >
> > + if (ipv6_addr_is_ll_mcast(&ipv6_hdr(skb)->daddr))
> > + BR_INPUT_SKB_CB(skb)->local_receive = 1;
> > +
> > if (ipv6_addr_is_all_snoopers(&ipv6_hdr(skb)->daddr)) {
> > err = br_ip6_multicast_mrd_rcv(br, port, skb);
> >
> > diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> > index b7a4942ff1b3..d76394ca4059 100644
> > --- a/net/bridge/br_private.h
> > +++ b/net/bridge/br_private.h
> > @@ -426,6 +426,7 @@ struct br_input_skb_cb {
> > #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
> > u8 igmp;
> > u8 mrouters_only:1;
> > + u8 local_receive:1;
> > #endif
> > u8 proxyarp_replied:1;
> > u8 src_port_isolated:1;
> > @@ -445,8 +446,10 @@ struct br_input_skb_cb {
> >
> > #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
> > # define BR_INPUT_SKB_CB_MROUTERS_ONLY(__skb) (BR_INPUT_SKB_CB(__skb)->mrouters_only)
> > +# define BR_INPUT_SKB_CB_LOCAL_RECEIVE(__skb) (BR_INPUT_SKB_CB(__skb)->local_receive)
> > #else
> > # define BR_INPUT_SKB_CB_MROUTERS_ONLY(__skb) (0)
> > +# define BR_INPUT_SKB_CB_LOCAL_RECEIVE(__skb) (0)
> > #endif
> >
> > #define br_printk(level, br, format, args...) \
> >
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