diff options
| author | Willem de Bruijn <willemb@google.com> | 2022-02-15 11:00:37 -0500 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-02-16 20:37:47 -0800 |
| commit | 0b0dff5b3b98c5c7ce848151df9da0b3cdf0cc8b (patch) | |
| tree | c0f0433207298092afc8b14516af5e140237f816 /net/ipv6/ip6_flowlabel.c | |
| parent | c832962ac972082b3a1f89775c9d4274c8cb5670 (diff) | |
ipv6: per-netns exclusive flowlabel checks
Ipv6 flowlabels historically require a reservation before use.
Optionally in exclusive mode (e.g., user-private).
Commit 59c820b2317f ("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: 59c820b2317f ("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>
Diffstat (limited to 'net/ipv6/ip6_flowlabel.c')
| -rw-r--r-- | net/ipv6/ip6_flowlabel.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c index aa673a6a7e43..ceb85c67ce39 100644 --- a/net/ipv6/ip6_flowlabel.c +++ b/net/ipv6/ip6_flowlabel.c @@ -450,8 +450,10 @@ fl_create(struct net *net, struct sock *sk, struct in6_flowlabel_req *freq, err = -EINVAL; goto done; } - if (fl_shared_exclusive(fl) || fl->opt) + if (fl_shared_exclusive(fl) || fl->opt) { + WRITE_ONCE(sock_net(sk)->ipv6.flowlabel_has_excl, 1); static_branch_deferred_inc(&ipv6_flowlabel_exclusive); + } return fl; done: |