linux/net/ipv6
Daniel Borkmann 89225d1ce6 net: ipv6: mld: fix v1/v2 switchback timeout to rfc3810, 9.12.
i) RFC3810, 9.2. Query Interval [QI] says:

   The Query Interval variable denotes the interval between General
   Queries sent by the Querier. Default value: 125 seconds. [...]

ii) RFC3810, 9.3. Query Response Interval [QRI] says:

  The Maximum Response Delay used to calculate the Maximum Response
  Code inserted into the periodic General Queries. Default value:
  10000 (10 seconds) [...] The number of seconds represented by the
  [Query Response Interval] must be less than the [Query Interval].

iii) RFC3810, 9.12. Older Version Querier Present Timeout [OVQPT] says:

  The Older Version Querier Present Timeout is the time-out for
  transitioning a host back to MLDv2 Host Compatibility Mode. When an
  MLDv1 query is received, MLDv2 hosts set their Older Version Querier
  Present Timer to [Older Version Querier Present Timeout].

  This value MUST be ([Robustness Variable] times (the [Query Interval]
  in the last Query received)) plus ([Query Response Interval]).

Hence, on *default* the timeout results in:

  [RV] = 2, [QI] = 125sec, [QRI] = 10sec
  [OVQPT] = [RV] * [QI] + [QRI] = 260sec

Having that said, we currently calculate [OVQPT] (here given as 'switchback'
variable) as ...

  switchback = (idev->mc_qrv + 1) * max_delay

RFC3810, 9.12. says "the [Query Interval] in the last Query received". In
section "9.14. Configuring timers", it is said:

  This section is meant to provide advice to network administrators on
  how to tune these settings to their network. Ambitious router
  implementations might tune these settings dynamically based upon
  changing characteristics of the network. [...]

iv) RFC38010, 9.14.2. Query Interval:

  The overall level of periodic MLD traffic is inversely proportional
  to the Query Interval. A longer Query Interval results in a lower
  overall level of MLD traffic. The value of the Query Interval MUST
  be equal to or greater than the Maximum Response Delay used to
  calculate the Maximum Response Code inserted in General Query
  messages.

I assume that was why switchback is calculated as is (3 * max_delay), although
this setting seems to be meant for routers only to configure their [QI]
interval for non-default intervals. So usage here like this is clearly wrong.

Concluding, the current behaviour in IPv6's multicast code is not conform
to the RFC as switch back is calculated wrongly. That is, it has a too small
value, so MLDv2 hosts switch back again to MLDv2 way too early, i.e. ~30secs
instead of ~260secs on default.

Hence, introduce necessary helper functions and fix this up properly as it
should be.

Introduced in 06da92283 ("[IPV6]: Add MLDv2 support."). Credits to Hannes
Frederic Sowa who also had a hand in this as well. Also thanks to Hangbin Liu
who did initial testing.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: David Stevens <dlstevens@us.ibm.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-09-04 14:53:20 -04:00
..
netfilter netfilter: SYNPROXY: let unrelated packets continue 2013-09-04 11:44:23 +02:00
addrconf_core.c ipv6: move in6_dev_finish_destroy() into core kernel 2013-08-31 22:30:00 -04:00
addrconf.c ipv6: move in6_dev_finish_destroy() into core kernel 2013-08-31 22:30:00 -04:00
addrlabel.c rtnetlink: Remove passing of attributes into rtnl_doit functions 2013-03-22 10:31:16 -04:00
af_inet6.c vxlan: add ipv6 proxy support 2013-08-31 22:30:01 -04:00
ah6.c net: Add skb_unclone() helper function. 2013-02-15 15:10:37 -05:00
anycast.c net: proc: change proc_net_remove to remove_proc_entry 2013-02-18 14:53:08 -05:00
datagram.c net: proc_fs: trivial: print UIDs as unsigned int 2013-08-15 14:37:46 -07:00
esp6.c net: esp{4,6}: fix potential MTU calculation overflows 2013-08-05 12:26:50 -07:00
exthdrs_core.c ipv6: Correct comparisons and calculations using skb->tail and skb-transport_header 2013-05-28 23:49:07 -07:00
exthdrs_offload.c ipv6: Pull IPv6 GSO registration out of the module 2012-11-15 17:39:24 -05:00
exthdrs.c ipv6: Store Router Alert option in IP6CB directly. 2013-01-13 20:17:14 -05:00
fib6_rules.c fib_rules: fix suppressor names and default values 2013-08-03 10:40:23 -07:00
icmp.c net: Convert uses of typedef ctl_table to struct ctl_table 2013-06-13 02:36:09 -07:00
inet6_connection_sock.c ipv6: use newly introduced __ipv6_addr_needs_scope_id and ipv6_iface_scope_id 2013-03-08 12:29:22 -05:00
inet6_hashtables.c soreuseport: TCP/IPv6 implementation 2013-01-23 13:44:01 -05:00
ip6_checksum.c ipv6: move csum_ipv6_magic() and udp6_csum_init() into static library 2013-01-08 17:56:10 -08:00
ip6_fib.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2013-08-16 15:37:26 -07:00
ip6_flowlabel.c ipv6 flowlabel: add __rcu annotations 2013-03-07 16:33:10 -05:00
ip6_gre.c tunnels: harmonize cleanup done on skb on rx path 2013-09-04 00:27:26 -04:00
ip6_icmp.c ipv6: Kill ipv6 dependency of icmpv6_send(). 2013-04-29 13:54:36 -04:00
ip6_input.c net: add SNMP counters tracking incoming ECN bits 2013-08-08 22:24:59 -07:00
ip6_offload.c ipv6: Add generic UDP Tunnel segmentation 2013-08-31 22:30:01 -04:00
ip6_offload.h ipv6: Pull IPv6 GSO registration out of the module 2012-11-15 17:39:24 -05:00
ip6_output.c ipv6: move ip6_local_out into core kernel 2013-08-31 22:30:00 -04:00
ip6_tunnel.c tunnels: harmonize cleanup done on skb on rx path 2013-09-04 00:27:26 -04:00
ip6mr.c tunnels: harmonize cleanup done on skb on rx path 2013-09-04 00:27:26 -04:00
ipcomp6.c ipv6: Add redirect support to all protocol icmp error handlers. 2012-07-12 00:25:15 -07:00
ipv6_sockglue.c ipv6: rename datagram_send_ctl and datagram_recv_ctl 2013-01-31 13:53:08 -05:00
Kconfig Tunneling: use IP Tunnel stats APIs. 2013-03-26 12:27:19 -04:00
Makefile net: ipv6: Add IPv6 support to the ping socket. 2013-05-25 21:07:49 -07:00
mcast.c net: ipv6: mld: fix v1/v2 switchback timeout to rfc3810, 9.12. 2013-09-04 14:53:20 -04:00
mip6.c ipv6: Correct comparisons and calculations using skb->tail and skb-transport_header 2013-05-28 23:49:07 -07:00
ndisc.c net: neighbour: Remove CONFIG_ARPD 2013-09-03 21:41:43 -04:00
netfilter.c netfilter: add nf_ipv6_ops hook to fix xt_addrtype with IPv6 2013-05-23 11:58:55 +02:00
output_core.c ipv6: move ip6_local_out into core kernel 2013-08-31 22:30:00 -04:00
ping.c net: ipv6: fix wrong ping_v6_sendmsg return value 2013-07-03 17:42:05 -07:00
proc.c net: add SNMP counters tracking incoming ECN bits 2013-08-08 22:24:59 -07:00
protocol.c ipv6: Pull IPv6 GSO registration out of the module 2012-11-15 17:39:24 -05:00
raw.c icmpv6_filter: allow ICMPv6 messages with bodies < 4 bytes 2013-08-02 15:15:50 -07:00
reassembly.c ipv6: drop packets with multiple fragmentation headers 2013-08-20 00:11:24 -07:00
route.c ipv6: move ip6_dst_hoplimit() into core kernel 2013-08-31 22:29:59 -04:00
sit.c tunnels: harmonize cleanup done on skb on rx path 2013-09-04 00:27:26 -04:00
syncookies.c net: syncookies: export cookie_v6_init_sequence/cookie_v6_check 2013-08-28 00:28:04 +02:00
sysctl_net_ipv6.c net: Convert uses of typedef ctl_table to struct ctl_table 2013-06-13 02:36:09 -07:00
tcp_ipv6.c tcp: Change return value of tcp_rcv_established() 2013-09-04 00:27:28 -04:00
tcpv6_offload.c net: Remove code duplication between offload structures 2012-11-15 17:39:51 -05:00
tunnel6.c net: ipv6: Standardize prefixes for message logging 2012-05-16 01:01:03 -04:00
udp_impl.h ipv6: do not clear pinet6 field 2013-05-11 16:26:38 -07:00
udp_offload.c net: unify skb_udp_tunnel_segment() and skb_udp6_tunnel_segment() 2013-08-31 22:30:01 -04:00
udp.c net: rename ll methods to busy-poll 2013-07-10 17:08:27 -07:00
udplite.c ipv6: do not clear pinet6 field 2013-05-11 16:26:38 -07:00
xfrm6_input.c netfilter: ipv6: use NFPROTO values for NF_HOOK invocation 2010-03-25 16:00:49 +01:00
xfrm6_mode_beet.c ipsec: be careful of non existing mac headers 2012-02-23 16:50:45 -05:00
xfrm6_mode_ro.c
xfrm6_mode_transport.c
xfrm6_mode_tunnel.c xfrm: allow to avoid copying DSCP during encapsulation 2013-03-06 07:02:45 +01:00
xfrm6_output.c xfrm6: remove unneeded NULL check in __xfrm6_output() 2012-02-01 02:52:48 -05:00
xfrm6_policy.c xfrm6: release dev before returning error 2013-05-11 17:40:15 -07:00
xfrm6_state.c ipv6: use IS_ENABLED() 2012-11-01 12:41:35 -04:00
xfrm6_tunnel.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00