[ovs-dev] [PATCH ovn v2 5/5] ovn-controller: Handle DNAT/no-NAT conntrack tuple collisions.
Dumitru Ceara
dceara at redhat.com
Thu Jun 10 19:37:48 UTC 2021
On 6/10/21 6:26 PM, Mark Gray wrote:
> On 09/06/2021 13:12, 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 <dceara at redhat.com>
>> ---
>> include/ovn/actions.h | 1
>> lib/actions.c | 31 ++++++++
>> tests/ovn.at | 2 -
>> tests/system-common-macros.at | 4 +
>> tests/system-ovn.at | 156 +++++++++++++++++++++++++++++++++++++++++
>> 5 files changed, 193 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/ovn/actions.h b/include/ovn/actions.h
>> index 040213177..f5eb01eb7 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;
>> diff --git a/lib/actions.c b/lib/actions.c
>> index b3433f49e..7010fab2b 100644
>> --- a/lib/actions.c
>> +++ b/lib/actions.c
>> @@ -742,6 +742,22 @@ 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 (ovs_feature_is_supported(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);
>>
>> @@ -792,6 +808,21 @@ 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 (ovs_feature_is_supported(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..1c11f9bab 100644
>> --- a/tests/system-ovn.at
>> +++ b/tests/system-ovn.at
>> @@ -5296,6 +5296,162 @@ 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_SKIP_IF([test $HAVE_NC = no])
>> +AT_KEYWORDS([ovnlb])
>> +
>> +CHECK_CONNTRACK()
>> +CHECK_CONNTRACK_NAT()
>> +ovn_start
>> +OVS_TRAFFIC_VSWITCHD_START()
>> +OVS_CHECK_CT_ZERO_SNAT()
>> +ADD_BR([br-int])
>> +
>> +# Set external-ids in br-int needed for ovn-controller
>> +ovs-vsctl \
>> + -- set Open_vSwitch . external-ids:system-id=hv1 \
>> + -- set Open_vSwitch . external-ids:ovn-remote=unix:$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
>> +
>> +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
>> +check 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])
>> +
>> +# Check conntrack.
>> +OVS_WAIT_UNTIL([test `ovs-appctl dpctl/dump-conntrack | \
>> +FORMAT_CT(42.42.42.2) | wc -l` = 1])
>> +
>> +# 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])
>> +
>> +# Check conntrack.
>> +AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(42.42.42.2) | \
>> +sed -e 's/zone=[[0-9]]*/zone=<cleared>/'], [0], [dnl
>> +tcp,orig=(src=42.42.42.3,dst=42.42.42.2,sport=<cleared>,dport=<cleared>),reply=(src=42.42.42.2,dst=42.42.42.3,sport=<cleared>,dport=<cleared>),zone=<cleared>,protoinfo=(state=<cleared>)
>> +tcp,orig=(src=42.42.42.3,dst=42.42.42.2,sport=<cleared>,dport=<cleared>),reply=(src=42.42.42.2,dst=42.42.42.3,sport=<cleared>,dport=<cleared>),zone=<cleared>,protoinfo=(state=<cleared>)
>> +])
>> +
>> +AT_CLEANUP
>> +])
>> +
>> +OVN_FOR_EACH_NORTHD([
>> +AT_SETUP([ovn -- load-balancer and firewall tuple conflict IPv6])
>> +AT_SKIP_IF([test $HAVE_NC = no])
>> +AT_KEYWORDS([ovnlb])
>> +
>> +CHECK_CONNTRACK()
>> +CHECK_CONNTRACK_NAT()
>> +ovn_start
>> +OVS_TRAFFIC_VSWITCHD_START()
>> +OVS_CHECK_CT_ZERO_SNAT()
>> +ADD_BR([br-int])
>> +
>> +# Set external-ids in br-int needed for ovn-controller
>> +ovs-vsctl \
>> + -- set Open_vSwitch . external-ids:system-id=hv1 \
>> + -- set Open_vSwitch . external-ids:ovn-remote=unix:$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 4242::1/64 \
>> + -- 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 [[6666::1]]:666 [[4242::2]]:4242 tcp \
>> + -- ls-lb-add ls lb-test
>> +
>> +ADD_NAMESPACES(vm1)
>> +ADD_VETH(vm1, vm1, br-int, "4242::2/64", "00:00:00:00:00:01", "4242::1")
>> +OVS_WAIT_UNTIL([test "$(ip netns exec vm1 ip a | grep 4242::2 | grep tentative)" = ""])
>> +
>> +ADD_NAMESPACES(vm2)
>> +ADD_VETH(vm2, vm2, br-int, "4242::3/64", "00:00:00:00:00:02", "4242::1")
>> +OVS_WAIT_UNTIL([test "$(ip netns exec vm2 ip a | grep 4242::3 | grep tentative)" = ""])
>> +
>> +# Wait for ovn-controller to catch up.
>> +wait_for_ports_up
>> +check ovn-nbctl --wait=hv sync
>> +
>> +# Start IPv6 TCP server on vm1.
>> +NETNS_DAEMONIZE([vm1], [nc -k -l 4242::2 4242], [nc-vm1.pid])
>> +
>> +# Make sure connecting to the VIP works.
>> +NS_CHECK_EXEC([vm2], [nc 6666::1 666 -p 2000 -z])
>> +
>> +# Start IPv6 TCP connection to VIP from vm2.
>> +NETNS_DAEMONIZE([vm2], [nc 6666::1 666 -p 2001], [nc1-vm2.pid])
>> +
>> +# Check conntrack.
>> +OVS_WAIT_UNTIL([test `ovs-appctl dpctl/dump-conntrack | \
>> +FORMAT_CT(4242::2) | wc -l` = 1])
>> +
>> +# Start IPv6 TCP connection to backend IP from vm2 which would require
>> +# additional source port translation to avoid a tuple conflict.
>> +NS_CHECK_EXEC([vm2], [nc 4242::2 4242 -p 2001 -z])
>> +
>> +# Check conntrack.
>> +AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(4242::2) | \
>> +sed -e 's/zone=[[0-9]]*/zone=<cleared>/'], [0], [dnl
>> +tcp,orig=(src=4242::3,dst=4242::2,sport=<cleared>,dport=<cleared>),reply=(src=4242::2,dst=4242::3,sport=<cleared>,dport=<cleared>),zone=<cleared>,protoinfo=(state=<cleared>)
>> +tcp,orig=(src=4242::3,dst=4242::2,sport=<cleared>,dport=<cleared>),reply=(src=4242::2,dst=4242::3,sport=<cleared>,dport=<cleared>),zone=<cleared>,protoinfo=(state=<cleared>)
>
> FORMAT_CT() obfuscates the ports. Is there anyway to confirm that they
> are being translated as expected?
>
Thanks for the review! Would the following incremental work for you?
diff --git a/tests/system-ovn.at b/tests/system-ovn.at
index 1c11f9bab..849a11d1b 100644
--- a/tests/system-ovn.at
+++ b/tests/system-ovn.at
@@ -5364,10 +5364,14 @@ FORMAT_CT(42.42.42.2) | wc -l` = 1])
NS_CHECK_EXEC([vm2], [nc 42.42.42.2 4242 -p 2001 -z])
# Check conntrack.
-AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(42.42.42.2) | \
-sed -e 's/zone=[[0-9]]*/zone=<cleared>/'], [0], [dnl
-tcp,orig=(src=42.42.42.3,dst=42.42.42.2,sport=<cleared>,dport=<cleared>),reply=(src=42.42.42.2,dst=42.42.42.3,sport=<cleared>,dport=<cleared>),zone=<cleared>,protoinfo=(state=<cleared>)
-tcp,orig=(src=42.42.42.3,dst=42.42.42.2,sport=<cleared>,dport=<cleared>),reply=(src=42.42.42.2,dst=42.42.42.3,sport=<cleared>,dport=<cleared>),zone=<cleared>,protoinfo=(state=<cleared>)
+AT_CHECK([ovs-appctl dpctl/dump-conntrack | grep 2001 | \
+grep "orig=.src=42\.42\.42\.3,dst=42\.42\.42\.2," | \
+sed -e 's/port=2001/port=<clnt_s_port>/g' \
+ -e 's/sport=4242,dport=[[0-9]]\+/sport=4242,dport=<rnd_port>/g' \
+ -e 's/state=[[0-9_A-Z]]*/state=<cleared>/g' \
+ -e 's/zone=[[0-9]]*/zone=<cleared>/' | sort], [0], [dnl
+tcp,orig=(src=42.42.42.3,dst=42.42.42.2,sport=<clnt_s_port>,dport=4242),reply=(src=42.42.42.2,dst=42.42.42.3,sport=4242,dport=<clnt_s_port>),zone=<cleared>,protoinfo=(state=<cleared>)
+tcp,orig=(src=42.42.42.3,dst=42.42.42.2,sport=<clnt_s_port>,dport=4242),reply=(src=42.42.42.2,dst=42.42.42.3,sport=4242,dport=<rnd_port>),zone=<cleared>,protoinfo=(state=<cleared>)
])
AT_CLEANUP
@@ -5443,10 +5447,14 @@ FORMAT_CT(4242::2) | wc -l` = 1])
NS_CHECK_EXEC([vm2], [nc 4242::2 4242 -p 2001 -z])
# Check conntrack.
-AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(4242::2) | \
-sed -e 's/zone=[[0-9]]*/zone=<cleared>/'], [0], [dnl
-tcp,orig=(src=4242::3,dst=4242::2,sport=<cleared>,dport=<cleared>),reply=(src=4242::2,dst=4242::3,sport=<cleared>,dport=<cleared>),zone=<cleared>,protoinfo=(state=<cleared>)
-tcp,orig=(src=4242::3,dst=4242::2,sport=<cleared>,dport=<cleared>),reply=(src=4242::2,dst=4242::3,sport=<cleared>,dport=<cleared>),zone=<cleared>,protoinfo=(state=<cleared>)
+AT_CHECK([ovs-appctl dpctl/dump-conntrack | grep 2001 | \
+grep "orig=.src=4242::3,dst=4242::2," | \
+sed -e 's/port=2001/port=<clnt_s_port>/g' \
+ -e 's/sport=4242,dport=[[0-9]]\+/sport=4242,dport=<rnd_port>/g' \
+ -e 's/state=[[0-9_A-Z]]*/state=<cleared>/g' \
+ -e 's/zone=[[0-9]]*/zone=<cleared>/' | sort], [0], [dnl
+tcp,orig=(src=4242::3,dst=4242::2,sport=<clnt_s_port>,dport=4242),reply=(src=4242::2,dst=4242::3,sport=4242,dport=<clnt_s_port>),zone=<cleared>,protoinfo=(state=<cleared>)
+tcp,orig=(src=4242::3,dst=4242::2,sport=<clnt_s_port>,dport=4242),reply=(src=4242::2,dst=4242::3,sport=4242,dport=<rnd_port>),zone=<cleared>,protoinfo=(state=<cleared>)
])
AT_CLEANUP
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