linux/net
Maciej Żenczykowski fb56be83e4 net-ipv6: on device mtu change do not add mtu to mtu-less routes
Routes can specify an mtu explicitly or inherit the mtu from
the underlying device - this inheritance is implemented in
dst->ops->mtu handlers ip6_mtu() and ip6_blackhole_mtu().

Currently changing the mtu of a device adds mtu explicitly
to routes using that device.

ie.
  # ip link set dev lo mtu 65536
  # ip -6 route add local 2000::1 dev lo
  # ip -6 route get 2000::1
  local 2000::1 dev lo  table local  src ...  metric 1024  pref medium

  # ip link set dev lo mtu 65535
  # ip -6 route get 2000::1
  local 2000::1 dev lo  table local  src ...  metric 1024  mtu 65535 pref medium

  # ip link set dev lo mtu 65536
  # ip -6 route get 2000::1
  local 2000::1 dev lo  table local  src ...  metric 1024  mtu 65536 pref medium

  # ip -6 route del local 2000::1

After this patch the route entry no longer changes unless it already has an mtu.
There is no need: this inheritance is already done in ip6_mtu()

  # ip link set dev lo mtu 65536
  # ip -6 route add local 2000::1 dev lo
  # ip -6 route add local 2000::2 dev lo mtu 2000
  # ip -6 route get 2000::1; ip -6 route get 2000::2
  local 2000::1 dev lo  table local  src ...  metric 1024  pref medium
  local 2000::2 dev lo  table local  src ...  metric 1024  mtu 2000 pref medium

  # ip link set dev lo mtu 65535
  # ip -6 route get 2000::1; ip -6 route get 2000::2
  local 2000::1 dev lo  table local  src ...  metric 1024  pref medium
  local 2000::2 dev lo  table local  src ...  metric 1024  mtu 2000 pref medium

  # ip link set dev lo mtu 1501
  # ip -6 route get 2000::1; ip -6 route get 2000::2
  local 2000::1 dev lo  table local  src ...  metric 1024  pref medium
  local 2000::2 dev lo  table local  src ...  metric 1024  mtu 1501 pref medium

  # ip link set dev lo mtu 65536
  # ip -6 route get 2000::1; ip -6 route get 2000::2
  local 2000::1 dev lo  table local  src ...  metric 1024  pref medium
  local 2000::2 dev lo  table local  src ...  metric 1024  mtu 65536 pref medium

  # ip -6 route del local 2000::1
  # ip -6 route del local 2000::2

This is desirable because changing device mtu and then resetting it
to the previous value shouldn't change the user visible routing table.

Signed-off-by: Maciej Żenczykowski <maze@google.com>
CC: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-11-09 13:19:32 -05:00
..
6lowpan 6lowpan: ndisc: no overreact if no short address is available 2016-09-19 20:19:34 +02:00
9p IB/core: add support to create a unsafe global rkey to ib_create_pd 2016-09-23 13:47:44 -04:00
802
8021q net: add recursion limit to GRO 2016-10-20 14:32:22 -04:00
appletalk appletalk: use IS_ENABLED() instead of checking for built-in or module 2016-09-10 21:19:10 -07:00
atm lec: use IS_ENABLED() instead of checking for built-in or module 2016-09-10 21:19:10 -07:00
ax25 AX.25: Close socket connection on session completion 2016-06-18 20:55:34 -07:00
batman-adv batman-adv: fix splat on disabling an interface 2016-10-21 14:47:02 +02:00
bluetooth Bluetooth: Fix append max 11 bytes of name to scan rsp data 2016-10-19 18:42:37 +02:00
bridge bridge: multicast: restore perm router ports on multicast enable 2016-10-18 13:52:13 -04:00
caif caif: Remove unneeded header file 2016-06-28 05:26:14 -04:00
can can: bcm: fix warning in bcm_connect/proc_register 2016-10-31 20:48:19 +01:00
ceph mm: replace get_user_pages_unlocked() write/force parameters with gup_flags 2016-10-18 14:13:37 -07:00
core dccp: do not release listeners too soon 2016-11-03 16:16:50 -04:00
dcb net/dcb: make dcbnl.c explicitly non-modular 2015-10-09 07:52:27 -07:00
dccp ipv6: dccp: add missing bind_conflict to dccp_ipv6_mapped 2016-11-03 16:50:27 -04:00
decnet net: fix decnet rtnexthop parsing 2016-07-05 14:08:47 -07:00
dns_resolver KEYS: Add a facility to restrict new links into a keyring 2016-04-11 22:37:37 +01:00
dsa net: dsa: add port fast ageing 2016-09-23 08:38:50 -04:00
ethernet net: add recursion limit to GRO 2016-10-20 14:32:22 -04:00
hsr net/hsr: Remove unused but set variable 2016-10-18 10:28:18 -04:00
ieee802154 ieee802154: 6lowpan: fix intra pan id check 2016-07-08 13:23:12 +02:00
ipv4 fib_trie: Correct /proc/net/route off by one error 2016-11-07 20:40:27 -05:00
ipv6 net-ipv6: on device mtu change do not add mtu to mtu-less routes 2016-11-09 13:19:32 -05:00
ipx
irda Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-09-23 06:46:57 -04:00
iucv Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-07-29 17:38:46 -07:00
kcm Merge branch 'work.splice_read' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-10-07 15:36:58 -07:00
key af_key: fix two typos 2015-10-23 03:05:19 -07:00
l2tp udp: must lock the socket in udp_disconnect() 2016-10-20 14:45:52 -04:00
l3mdev net: ipv6: Remove l3mdev_get_saddr6 2016-09-10 23:12:53 -07:00
lapb net/lapb: tuse %*ph to dump buffers 2016-05-29 22:33:25 -07:00
llc llc: switch type to bool as the timeout is only tested versus 0 2016-09-17 10:05:05 -04:00
mac80211 mac80211: move struct aead_req off the stack 2016-10-17 16:14:04 +02:00
mac802154 mac802154: use rate limited warnings for malformed frames 2016-09-19 20:19:34 +02:00
mpls mpls: move mpls_hdr to a common location 2016-10-03 02:00:21 -04:00
ncsi net/ncsi: Improve HNCDSC AEN handler 2016-10-20 11:23:08 -04:00
netfilter netfilter: fix nf_queue handling 2016-10-20 19:59:59 +02:00
netlabel netlabel: Implement CALIPSO config functions for SMACK. 2016-06-27 15:06:18 -04:00
netlink genetlink: fix a memory leak on error path 2016-11-03 16:52:29 -04:00
netrom netfilter: Remove spurios included of netfilter.h 2015-06-18 21:14:32 +02:00
nfc NFC: digital: Fix RTOX supervisor PDU handling 2016-07-11 02:02:03 +02:00
openvswitch openvswitch: add NETIF_F_HW_VLAN_STAG_TX to internal dev 2016-10-13 10:03:23 -04:00
packet packet: on direct_xmit, limit tso and csum to supported devices 2016-10-29 15:02:15 -04:00
phonet sock: struct proto hash function may error 2016-02-11 03:54:14 -05:00
qrtr Merge tag 'qcom-soc-for-4.7-2' into net-next 2016-05-17 14:11:19 -04:00
rds rds: debug messages are enabled by default 2016-10-29 15:55:57 -04:00
rfkill rfkill: Use switch to demux userspace operations 2016-04-05 10:48:53 +02:00
rose rose: limit sk_filter trim to payload 2016-07-13 11:53:40 -07:00
rxrpc rxrpc: Fix checking of error from ip6_route_output() 2016-10-13 08:43:17 +01:00
sched net_sched actions: use nla_parse_nested() 2016-10-29 15:01:01 -04:00
sctp sctp: assign assoc_id earlier in __sctp_connect 2016-11-07 13:18:37 -05:00
strparser strparser: Propagate correct error code in strp_recv() 2016-10-12 01:51:49 -04:00
sunrpc NFS client updates for Linux 4.9 2016-10-13 21:28:20 -07:00
switchdev switchdev: Execute bridge ndos only for bridge ports 2016-10-19 10:58:04 -04:00
tipc tipc: fix broadcast link synchronization problem 2016-10-29 17:21:09 -04:00
unix unix: escape all null bytes in abstract unix domain socket 2016-11-01 12:15:13 -04:00
vmw_vsock VSOCK: Don't dec ack backlog twice for rejected connections 2016-09-27 07:59:25 -04:00
wimax net:wimax: Fix doucble word "the the" in networking.xml 2015-08-09 22:43:52 -07:00
wireless cfg80211: process events caused by suspend before suspending 2016-10-26 07:59:52 +02:00
x25 net: x25: remove null checks on arrays calling_ae and called_ae 2016-09-09 18:13:30 -07:00
xfrm proc: Reduce cache miss in xfrm_statistics_seq_show 2016-09-30 01:50:45 -04:00
Kconfig strparser: Stream parser for messages 2016-08-17 19:36:23 -04:00
Makefile strparser: Stream parser for messages 2016-08-17 19:36:23 -04:00
compat.c packet: compat support for sock_fprog 2016-06-09 23:41:03 -07:00
socket.c sock: fix sendmmsg for partial sendmsg 2016-11-09 13:18:12 -05:00
sysctl_net.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2016-10-06 09:52:23 -07:00