On 6/4/21 4:51 PM, Mark Gray wrote: > On 03/06/2021 16:06, Dumitru Ceara wrote: >> Assuming a load balancer, LB1, with: >> - VIP: 42.42.42.42:4242 >> - backend: 42.42.42.1:2121 >> >> A client might connect to the backend either directly or through the >> VIP. If the first connection is via the VIP and the second connection >> is direct but happens to use the same source L4 port, OVN should make >> sure that the second connection is SNATed (source port translation) in >> order to avoid a tuple collision at commit time. >> >> For example: >> 1. Session via the VIP: >> - original packet: src=42.42.42.2:2000, dst=42.42.42.42:4242 >> - after DNAT: src=42.42.42.2:2000, dst=42.42.42.1:2121 >> 2. Session directly connected to the backend: >> - original packet: src=42.42.42.2:2000, dst=42.42.42.1:2121 >> - in acl stage committing this connection would fail. >> >> In order to avoid this we now use the all-zero-ip NAT OVS feature when >> committing conneections in the ACL stage. This translates to a no-op >> SNAT when there's no tuple collision, and performs source port >> translation when a tuple collision would happen. >> >> We program flows to perform all-zero-ip NAT conditionally, only if the >> datapath being used supports it. >> >> Reported-at: https://bugzilla.redhat.com/1939676 >> Signed-off-by: Dumitru Ceara <[email protected]> >> --- >> controller/lflow.c | 1 >> include/ovn/actions.h | 4 + >> lib/actions.c | 34 ++++++++++ >> tests/ovn.at | 2 - >> tests/system-common-macros.at | 4 + >> tests/system-ovn.at | 138 >> +++++++++++++++++++++++++++++++++++++++++ >> 6 files changed, 180 insertions(+), 3 deletions(-) >> >> diff --git a/controller/lflow.c b/controller/lflow.c >> index 680b8cca1..af6a237d1 100644 >> --- a/controller/lflow.c >> +++ b/controller/lflow.c >> @@ -582,6 +582,7 @@ add_matches_to_flow_table(const struct >> sbrec_logical_flow *lflow, >> .is_switch = datapath_is_switch(dp), >> .group_table = l_ctx_out->group_table, >> .meter_table = l_ctx_out->meter_table, >> + .dp_features = ovs_feature_support_get(), >> .lflow_uuid = lflow->header_.uuid, >> >> .pipeline = ingress ? OVNACT_P_INGRESS : OVNACT_P_EGRESS, >> diff --git a/include/ovn/actions.h b/include/ovn/actions.h >> index 040213177..35983498b 100644 >> --- a/include/ovn/actions.h >> +++ b/include/ovn/actions.h >> @@ -25,6 +25,7 @@ >> #include "openvswitch/hmap.h" >> #include "openvswitch/uuid.h" >> #include "util.h" >> +#include "ovn/features.h" >> >> struct expr; >> struct lexer; >> @@ -756,6 +757,9 @@ struct ovnact_encode_params { >> /* A struct to figure out the meter_id for meter actions. */ >> struct ovn_extend_table *meter_table; >> >> + /* OVS datapath supported features. */ >> + enum ovs_feature_support dp_features; >> + >> /* The logical flow uuid that drove this action. */ >> struct uuid lflow_uuid; >> >> diff --git a/lib/actions.c b/lib/actions.c >> index b3433f49e..c8c2443ce 100644 >> --- a/lib/actions.c >> +++ b/lib/actions.c >> @@ -732,7 +732,7 @@ format_CT_COMMIT_V1(const struct ovnact_ct_commit_v1 >> *cc, struct ds *s) >> >> static void >> encode_CT_COMMIT_V1(const struct ovnact_ct_commit_v1 *cc, >> - const struct ovnact_encode_params *ep OVS_UNUSED, >> + const struct ovnact_encode_params *ep, >> struct ofpbuf *ofpacts) >> { >> struct ofpact_conntrack *ct = ofpact_put_CT(ofpacts); >> @@ -742,6 +742,21 @@ encode_CT_COMMIT_V1(const struct ovnact_ct_commit_v1 >> *cc, >> ct->zone_src.ofs = 0; >> ct->zone_src.n_bits = 16; >> >> + /* If the datapath supports all-zero SNAT then use it to avoid tuple >> + * collisions at commit time between NATed and firewalled-only sessions. >> + */ >> + if (ep->dp_features & OVS_CT_ZERO_SNAT_SUPPORT) { >> + size_t nat_offset = ofpacts->size; >> + ofpbuf_pull(ofpacts, nat_offset); >> + >> + struct ofpact_nat *nat = ofpact_put_NAT(ofpacts); >> + nat->flags = 0; >> + nat->range_af = AF_UNSPEC; >> + nat->flags |= NX_NAT_F_SRC; >> + ofpacts->header = ofpbuf_push_uninit(ofpacts, nat_offset); >> + ct = ofpacts->header; >> + } >> + >> size_t set_field_offset = ofpacts->size; >> ofpbuf_pull(ofpacts, set_field_offset); >> >> @@ -780,7 +795,7 @@ format_CT_COMMIT_V2(const struct ovnact_nest *on, struct >> ds *s) >> >> static void >> encode_CT_COMMIT_V2(const struct ovnact_nest *on, >> - const struct ovnact_encode_params *ep OVS_UNUSED, >> + const struct ovnact_encode_params *ep, >> struct ofpbuf *ofpacts) >> { >> struct ofpact_conntrack *ct = ofpact_put_CT(ofpacts); >> @@ -792,6 +807,21 @@ encode_CT_COMMIT_V2(const struct ovnact_nest *on, >> ct->zone_src.ofs = 0; >> ct->zone_src.n_bits = 16; >> >> + /* If the datapath supports all-zero SNAT then use it to avoid tuple >> + * collisions at commit time between NATed and firewalled-only sessions. >> + */ >> + if (ep->dp_features & OVS_CT_ZERO_SNAT_SUPPORT) { >> + size_t nat_offset = ofpacts->size; >> + ofpbuf_pull(ofpacts, nat_offset); >> + >> + struct ofpact_nat *nat = ofpact_put_NAT(ofpacts); >> + nat->flags = 0; >> + nat->range_af = AF_UNSPEC; >> + nat->flags |= NX_NAT_F_SRC; >> + ofpacts->header = ofpbuf_push_uninit(ofpacts, nat_offset); >> + ct = ofpacts->header; >> + } >> + >> size_t set_field_offset = ofpacts->size; >> ofpbuf_pull(ofpacts, set_field_offset); >> >> diff --git a/tests/ovn.at b/tests/ovn.at >> index f26894ce4..638aa5010 100644 >> --- a/tests/ovn.at >> +++ b/tests/ovn.at >> @@ -23109,7 +23109,7 @@ AT_CHECK([ >> for hv in 1 2; do >> grep table=15 hv${hv}flows | \ >> grep "priority=100" | \ >> - grep -c >> "ct(commit,zone=NXM_NX_REG11\\[[0..15\\]],exec(move:NXM_OF_ETH_SRC\\[[\\]]->NXM_NX_CT_LABEL\\[[32..79\\]],load:0x[[0-9]]->NXM_NX_CT_LABEL\\[[80..95\\]]))" >> + grep -c >> "ct(commit,zone=NXM_NX_REG11\\[[0..15\\]],.*exec(move:NXM_OF_ETH_SRC\\[[\\]]->NXM_NX_CT_LABEL\\[[32..79\\]],load:0x[[0-9]]->NXM_NX_CT_LABEL\\[[80..95\\]]))" >> >> grep table=22 hv${hv}flows | \ >> grep "priority=200" | \ >> diff --git a/tests/system-common-macros.at b/tests/system-common-macros.at >> index c8fa6f03f..b742a2cb9 100644 >> --- a/tests/system-common-macros.at >> +++ b/tests/system-common-macros.at >> @@ -330,3 +330,7 @@ m4_define([OVS_CHECK_IPROUTE_ENCAP], >> # OVS_CHECK_CT_CLEAR() >> m4_define([OVS_CHECK_CT_CLEAR], >> [AT_SKIP_IF([! grep -q "Datapath supports ct_clear action" >> ovs-vswitchd.log])]) >> + >> +# OVS_CHECK_CT_ZERO_SNAT() >> +m4_define([OVS_CHECK_CT_ZERO_SNAT], >> + [AT_SKIP_IF([! grep -q "Datapath supports ct_zero_snat" >> ovs-vswitchd.log])])) >> diff --git a/tests/system-ovn.at b/tests/system-ovn.at >> index 310bd3d5a..61d6bfc86 100644 >> --- a/tests/system-ovn.at >> +++ b/tests/system-ovn.at >> @@ -5296,6 +5296,144 @@ OVS_TRAFFIC_VSWITCHD_STOP(["/failed to query port >> patch-.*/d >> AT_CLEANUP >> ]) >> >> +OVN_FOR_EACH_NORTHD([ >> +AT_SETUP([ovn -- load-balancer and firewall tuple conflict IPv4]) >> +AT_KEYWORDS([ovnlb]) >> + >> +CHECK_CONNTRACK() >> +CHECK_CONNTRACK_NAT() >> +ovn_start >> +OVS_TRAFFIC_VSWITCHD_START() >> +OVS_CHECK_CT_ZERO_SNAT() >> +ADD_BR([br-int]) >> + >> +# Set external-ids in br-int needed for ovn-controller >> +ovs-vsctl \ >> + -- set Open_vSwitch . external-ids:system-id=hv1 \ >> + -- set Open_vSwitch . >> external-ids:ovn-remote=unix:$ovs_base/ovn-sb/ovn-sb.sock \ >> + -- set Open_vSwitch . external-ids:ovn-encap-type=geneve \ >> + -- set Open_vSwitch . external-ids:ovn-encap-ip=169.0.0.1 \ >> + -- set bridge br-int fail-mode=secure >> other-config:disable-in-band=true >> + >> +# Start ovn-controller >> +start_daemon ovn-controller >> + >> +# Logical network: >> +# 1 logical switch connetected to one logical router. >> +# 2 VMs, one used as backend for a load balancer. >> + >> +check ovn-nbctl \ >> + -- lr-add rtr \ >> + -- lrp-add rtr rtr-ls 00:00:00:00:01:00 42.42.42.1/24 \ >> + -- ls-add ls \ >> + -- lsp-add ls ls-rtr \ >> + -- lsp-set-addresses ls-rtr 00:00:00:00:01:00 \ >> + -- lsp-set-type ls-rtr router \ >> + -- lsp-set-options ls-rtr router-port=rtr-ls \ >> + -- lsp-add ls vm1 -- lsp-set-addresses vm1 00:00:00:00:00:01 \ >> + -- lsp-add ls vm2 -- lsp-set-addresses vm2 00:00:00:00:00:02 \ >> + -- lb-add lb-test 66.66.66.66:666 42.42.42.2:4242 tcp \ >> + -- ls-lb-add ls lb-test > > Will this work for a DNAT entry instead of a load-balancer? As you know, > the flows are slightly different. Will this work when combined with > forcing SNAT? Do we need to check this?
We already have system tests that test DNAT and load balancer force SNAT. I thought we're already covered by those. > >> + >> +ADD_NAMESPACES(vm1) >> +ADD_VETH(vm1, vm1, br-int, "42.42.42.2/24", "00:00:00:00:00:01", >> "42.42.42.1") >> + >> +ADD_NAMESPACES(vm2) >> +ADD_VETH(vm2, vm2, br-int, "42.42.42.3/24", "00:00:00:00:00:02", >> "42.42.42.1") >> + >> +# Wait for ovn-controller to catch up. >> +wait_for_ports_up >> +ovn-nbctl --wait=hv sync >> + >> +# Start IPv4 TCP server on vm1. >> +NETNS_DAEMONIZE([vm1], [nc -k -l 42.42.42.2 4242], [nc-vm1.pid]) >> + >> +# Make sure connecting to the VIP works. >> +NS_CHECK_EXEC([vm2], [nc 66.66.66.66 666 -p 2000 -z]) >> + >> +# Start IPv4 TCP connection to VIP from vm2. >> +NETNS_DAEMONIZE([vm2], [nc 66.66.66.66 666 -p 2001], [nc1-vm2.pid]) > > I feel like there should also be some kind of ping test to check that > the return path works as expected. Is there a reason why you did not do > that? The goal of the test is to make sure that the direct connection (towards 42.42.42.2:4242) below is established successfully. For the connection via the VIP there's the part above that performs the full TCP 3way handshake: NS_CHECK_EXEC([vm2], [nc 66.66.66.66 666 -p 2000 -z]) > >> + >> +# Check conntrack. >> +OVS_WAIT_UNTIL([ovs-appctl dpctl/dump-conntrack | grep ESTABLISHED | >> FORMAT_CT(42.42.42.2)]) >> + >> +# Start IPv4 TCP connection to backend IP from vm2 which would require >> +# additional source port translation to avoid a tuple conflict. >> +NS_CHECK_EXEC([vm2], [nc 42.42.42.2 4242 -p 2001 -z]) > > Should there be another check to ensure that the conntrack entries are > setup as expected? > I initially wanted to add one but there are differences in the way the TCP state machine is implemented in userspace conntrack vs kernel conntrack and I couldn't come up with something that would pass on both. I'll try some more though. Thanks for the reviews! Regards, Dumitru _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
