linux_dsm_epyc7002/net/ipv6
Stefano Brivio e9fa1495d7 ipv6: Reflect MTU changes on PMTU of exceptions for MTU-less routes
Currently, administrative MTU changes on a given netdevice are
not reflected on route exceptions for MTU-less routes, with a
set PMTU value, for that device:

 # ip -6 route get 2001:db8::b
 2001:db8::b from :: dev vti_a proto kernel src 2001:db8::a metric 256 pref medium
 # ping6 -c 1 -q -s10000 2001:db8::b > /dev/null
 # ip netns exec a ip -6 route get 2001:db8::b
 2001:db8::b from :: dev vti_a src 2001:db8::a metric 0
     cache expires 571sec mtu 4926 pref medium
 # ip link set dev vti_a mtu 3000
 # ip -6 route get 2001:db8::b
 2001:db8::b from :: dev vti_a src 2001:db8::a metric 0
     cache expires 571sec mtu 4926 pref medium
 # ip link set dev vti_a mtu 9000
 # ip -6 route get 2001:db8::b
 2001:db8::b from :: dev vti_a src 2001:db8::a metric 0
     cache expires 571sec mtu 4926 pref medium

The first issue is that since commit fb56be83e4 ("net-ipv6: on
device mtu change do not add mtu to mtu-less routes") we don't
call rt6_exceptions_update_pmtu() from rt6_mtu_change_route(),
which handles administrative MTU changes, if the regular route
is MTU-less.

However, PMTU exceptions should be always updated, as long as
RTAX_MTU is not locked. Keep the check for MTU-less main route,
as introduced by that commit, but, for exceptions,
call rt6_exceptions_update_pmtu() regardless of that check.

Once that is fixed, one problem remains: MTU changes are not
reflected if the new MTU is higher than the previous one,
because rt6_exceptions_update_pmtu() doesn't allow that. We
should instead allow PMTU increase if the old PMTU matches the
local MTU, as that implies that the old MTU was the lowest in the
path, and PMTU discovery might lead to different results.

The existing check in rt6_mtu_change_route() correctly took that
case into account (for regular routes only), so factor it out
and re-use it also in rt6_exceptions_update_pmtu().

While at it, fix comments style and grammar, and try to be a bit
more descriptive.

Reported-by: Xiumei Mu <xmu@redhat.com>
Fixes: fb56be83e4 ("net-ipv6: on device mtu change do not add mtu to mtu-less routes")
Fixes: f5bbe7ee79 ("ipv6: prepare rt6_mtu_change() for exception table")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Acked-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-07 13:17:50 -05:00
..
ila
netfilter net: rename skb_gso_validate_mtu -> skb_gso_validate_network_len 2018-03-04 17:49:17 -05:00
addrconf_core.c
addrconf.c ipv6: addrconf: break critical section in addrconf_verify_rtnl() 2018-01-29 14:23:38 -05:00
addrlabel.c
af_inet6.c ipv6: Fix SO_REUSEPORT UDP socket with implicit sk_ipv6only 2018-01-29 11:37:40 -05:00
ah6.c
anycast.c net: delete /proc THIS_MODULE references 2018-01-16 15:01:33 -05:00
calipso.c
datagram.c
esp6_offload.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-23 13:51:56 -05:00
esp6.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-17 00:10:42 -05:00
exthdrs_core.c
exthdrs_offload.c
exthdrs.c ipv6: sr: fix TLVs not being copied using setsockopt 2018-01-10 16:03:55 -05:00
fib6_notifier.c
fib6_rules.c
fou6.c
icmp.c
inet6_connection_sock.c
inet6_hashtables.c
ip6_checksum.c udplite: fix partial checksum initialization 2018-02-16 15:57:42 -05:00
ip6_fib.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-19 22:59:33 -05:00
ip6_flowlabel.c net: delete /proc THIS_MODULE references 2018-01-16 15:01:33 -05:00
ip6_gre.c net: erspan: fix erspan config overwrite 2018-02-06 11:32:49 -05:00
ip6_icmp.c
ip6_input.c
ip6_offload.c
ip6_offload.h
ip6_output.c net: rename skb_gso_validate_mtu -> skb_gso_validate_network_len 2018-03-04 17:49:17 -05:00
ip6_tunnel.c ip6_tunnel: fix IFLA_MTU ignored on NEWLINK 2018-02-27 14:36:28 -05:00
ip6_udp_tunnel.c
ip6_vti.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-29 10:15:51 -05:00
ip6mr.c ip6mr: fix stale iterator 2018-01-31 10:26:30 -05:00
ipcomp6.c
ipv6_sockglue.c netfilter: drop outermost socket lock in getsockopt() 2018-02-14 20:44:42 +01:00
Kconfig
Makefile
mcast_snoop.c
mcast.c build_bug.h: remove BUILD_BUG_ON_NULL() 2018-02-06 18:32:46 -08:00
mip6.c
ndisc.c net: ipv6: send unsolicited NA after DAD 2018-01-29 14:18:38 -05:00
netfilter.c netfilter: use skb_to_full_sk in ip6_route_me_harder 2018-02-25 20:51:13 +01:00
output_core.c
ping.c
proc.c net: delete /proc THIS_MODULE references 2018-01-16 15:01:33 -05:00
protocol.c
raw.c Currently, hardened usercopy performs dynamic bounds checking on slab 2018-02-03 16:25:42 -08:00
reassembly.c
route.c ipv6: Reflect MTU changes on PMTU of exceptions for MTU-less routes 2018-03-07 13:17:50 -05:00
seg6_hmac.c
seg6_iptunnel.c
seg6_local.c
seg6.c
sit.c sit: fix IFLA_MTU ignored on NEWLINK 2018-02-27 14:36:28 -05:00
syncookies.c
sysctl_net_ipv6.c
tcp_ipv6.c tcp: tracepoint: only call trace_tcp_send_reset with full socket 2018-02-07 22:00:42 -05:00
tcpv6_offload.c gso: validate gso_type in GSO handlers 2018-01-22 16:01:30 -05:00
tunnel6.c
udp_impl.h
udp_offload.c gso: validate gso_type in GSO handlers 2018-01-22 16:01:30 -05:00
udp.c net: delete /proc THIS_MODULE references 2018-01-16 15:01:33 -05:00
udplite.c net: delete /proc THIS_MODULE references 2018-01-16 15:01:33 -05:00
xfrm6_input.c
xfrm6_mode_beet.c
xfrm6_mode_ro.c
xfrm6_mode_transport.c
xfrm6_mode_tunnel.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-24 23:44:15 -05:00
xfrm6_output.c net: xfrm: use skb_gso_validate_network_len() to check gso sizes 2018-03-04 17:49:17 -05:00
xfrm6_policy.c
xfrm6_protocol.c
xfrm6_state.c
xfrm6_tunnel.c