kernel_optimize_test/net
Willem de Bruijn 4f523f15e5 ipv6: per-netns exclusive flowlabel checks
commit 0b0dff5b3b98c5c7ce848151df9da0b3cdf0cc8b upstream.

Ipv6 flowlabels historically require a reservation before use.
Optionally in exclusive mode (e.g., user-private).

Commit 59c820b231 ("ipv6: elide flowlabel check if no exclusive
leases exist") introduced a fastpath that avoids this check when no
exclusive leases exist in the system, and thus any flowlabel use
will be granted.

That allows skipping the control operation to reserve a flowlabel
entirely. Though with a warning if the fast path fails:

  This is an optimization. Robust applications still have to revert to
  requesting leases if the fast path fails due to an exclusive lease.

Still, this is subtle. Better isolate network namespaces from each
other. Flowlabels are per-netns. Also record per-netns whether
exclusive leases are in use. Then behavior does not change based on
activity in other netns.

Changes
  v2
    - wrap in IS_ENABLED(CONFIG_IPV6) to avoid breakage if disabled

Fixes: 59c820b231 ("ipv6: elide flowlabel check if no exclusive leases exist")
Link: https://lore.kernel.org/netdev/MWHPR2201MB1072BCCCFCE779E4094837ACD0329@MWHPR2201MB1072.namprd22.prod.outlook.com/
Reported-by: Congyu Liu <liu3101@purdue.edu>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Tested-by: Congyu Liu <liu3101@purdue.edu>
Link: https://lore.kernel.org/r/20220215160037.1976072-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-02-23 12:01:01 +01:00
..
6lowpan
9p
802
8021q
appletalk
atm
ax25
batman-adv
bluetooth
bpf
bpfilter
bridge
caif
can
ceph
core
dcb
dccp
decnet
dns_resolver
dsa
ethernet
ethtool
hsr
ieee802154
ife
ipv4
ipv6
iucv
kcm
key
l2tp
l3mdev
lapb
llc
mac80211
mac802154
mpls
mptcp
ncsi
netfilter
netlabel
netlink
netrom
nfc
nsh
openvswitch
packet
phonet
psample
qrtr
rds
rfkill
rose
rxrpc
sched
sctp
smc
strparser
sunrpc
switchdev
tipc
tls
unix
vmw_vsock
wimax
wireless
x25
xdp
xfrm
compat.c
devres.c
Kconfig
Makefile
socket.c
sysctl_net.c