On 18/02/2021 19:00, [email protected] wrote: > From: Numan Siddique <[email protected]> > > When a Gateway router is configured with a load balancer > and it is also configured with options:lb_force_snat_ip=<IP>, > OVN after load balancing the destination IP to one of the > backend also does a NAT on the source ip with the > lb_force_snat_ip if the packet is destined to a load balancer > VIP. > > There is a problem with the snat of source ip to 'lb_force_snat_ip' > in one particular usecase. When the packet enters the Gateway router > from a provider logical switch destined to the load balancer VIP, > then it is first load balanced to one of the backend and then > the source ip is snatted to 'lb_force_snat_ip'. If the chosen > backend is reachable via the provider logical switch, then the > packet is hairpinned back and it may hit the wire with > the source ip 'lb_force_snat_ip'. If 'lb_force_snat_ip' happens > to be an OVN internal IP then the packet may be dropped. > > This patch addresses this issue by providing the option to > set the option - 'lb_force_snat_ip=router_ip'. If 'router_ip' > is set, then OVN will snat the load balanced packet to the > router ip of the logical router port which is chosen as 'outport' > in lr_in_ip_routing stage. > > Example. > > If the gateway router is > > ovn-nbctl show lr0 > router 68f20092-5563-44b8-9ccb-b11de3e3a66c (lr0) > port lr0-sw0 > mac: "00:00:00:00:ff:01" > networks: ["10.0.0.1/24"] > port lr0-public > mac: "00:00:20:20:12:13" > networks: ["172.168.0.100/24"] > > Then the below logical flows are added if 'lb_force_snat_ip' > is configured to 'router_ip'. > > table=1 (lr_out_snat), priority=110 > match=(flags.force_snat_for_lb == 1 && ip4 && outport == "lr0-public"), > action=(ct_snat(172.168.0.100);) > > table=1 (lr_out_snat), priority=110 > match=(flags.force_snat_for_lb == 1 && ip4 && outport == "lr0-sw0") > action=(ct_snat(10.0.0.1);) > > For the above described scenario, the packet will have source ip as > 172.168.0.100 which belongs to the provider logical switch CIDR. > > Reported-by: Tim Rozet <[email protected]> > Signed-off-by: Numan Siddique <[email protected]> > --- > northd/ovn-northd.8.xml | 35 ++++++++++++++++ > northd/ovn-northd.c | 91 +++++++++++++++++++++++++++++++++++++---- > ovn-nb.xml | 33 ++++++++++----- > tests/ovn-northd.at | 79 +++++++++++++++++++++++++++++++++++ > 4 files changed, 220 insertions(+), 18 deletions(-) > > diff --git a/northd/ovn-northd.8.xml b/northd/ovn-northd.8.xml > index 2f8b4e8c30..1d8f5edee1 100644 > --- a/northd/ovn-northd.8.xml > +++ b/northd/ovn-northd.8.xml > @@ -3654,6 +3654,32 @@ nd_ns { > <code>flags.force_snat_for_dnat == 1 && ip</code> with an > action <code>ct_snat(<var>B</var>);</code>. > </p> > + </li> > + > + <li> > + <p> > + If the Gateway router in the OVN Northbound database has been > + configured to force SNAT a packet (that has been previously > + load-balanced) using router IP (i.e <ref column="options" > + table="Logical_Router"/>:lb_force_snat_ip=router_ip), then for > + each logical router port <var>P</var> attached to the Gateway > + router, a priority-110 flow matches > + <code>flags.force_snat_for_lb == 1 && outport == > <var>P</var> > + </code> with an action <code>ct_snat(<var>R</var>);</code> > + where <var>R</var> is the IP configured on the router port. > + If <code>R</code> is an IPv4 address then the match will also > + include <code>ip4</code> and if it is an IPv6 address, then the > + match will also include <code>ip6</code>. > + </p> > + > + <p> > + If the logical router port <var>P</var> is configured with multiple > + IPv4 and multiple IPv6 addresses, only the first IPv4 and first > IPv6 > + address is considered. > + </p> > + </li> > + > + <li> > <p> > If the Gateway router in the OVN Northbound database has been > configured to force SNAT a packet (that has been previously > @@ -3661,6 +3687,9 @@ nd_ns { > <code>flags.force_snat_for_lb == 1 && ip</code> with an > action <code>ct_snat(<var>B</var>);</code>. > </p> > + </li> > + > + <li> > <p> > For each configuration in the OVN Northbound database, that asks > to change the source IP address of a packet from an IP address of > @@ -3674,14 +3703,18 @@ nd_ns { > options, then the action would be <code>ip4/6.src= > (<var>B</var>)</code>. > </p> > + </li> > > + <li> > <p> > If the NAT rule has <code>allowed_ext_ips</code> configured, then > there is an additional match <code>ip4.dst == <var>allowed_ext_ips > </var></code>. Similarly, for IPV6, match would be <code>ip6.dst == > <var>allowed_ext_ips</var></code>. > </p> > + </li> > > + <li> > <p> > If the NAT rule has <code>exempted_ext_ips</code> set, then > there is an additional flow configured at the priority + 1 of > @@ -3690,7 +3723,9 @@ nd_ns { > </code>. This flow is used to bypass the ct_snat action for a > packet > which is destinted to <code>exempted_ext_ips</code>. > </p> > + </li> > > + <li> > <p> > A priority-0 logical flow with match <code>1</code> has actions > <code>next;</code>. > diff --git a/northd/ovn-northd.c b/northd/ovn-northd.c > index 39d7987820..0bbe92c09d 100644 > --- a/northd/ovn-northd.c > +++ b/northd/ovn-northd.c > @@ -624,6 +624,7 @@ struct ovn_datapath { > > struct lport_addresses dnat_force_snat_addrs; > struct lport_addresses lb_force_snat_addrs; > + bool lb_force_snat_router_ip; > > struct ovn_port **localnet_ports; > size_t n_localnet_ports; > @@ -717,14 +718,28 @@ init_nat_entries(struct ovn_datapath *od) > } > } > > - if (get_force_snat_ip(od, "lb", &od->lb_force_snat_addrs)) { > - if (od->lb_force_snat_addrs.n_ipv4_addrs) { > - snat_ip_add(od, od->lb_force_snat_addrs.ipv4_addrs[0].addr_s, > - NULL); > - } > - if (od->lb_force_snat_addrs.n_ipv6_addrs) { > - snat_ip_add(od, od->lb_force_snat_addrs.ipv6_addrs[0].addr_s, > - NULL); > + /* Check if 'lb_force_snat_ip' is configured with 'router_ip'. */ > + const char *lb_force_snat = > + smap_get(&od->nbr->options, "lb_force_snat_ip"); > + if (lb_force_snat && !strcmp(lb_force_snat, "router_ip") > + && smap_get(&od->nbr->options, "chassis")) { > + /* Set it to true only if its gateway router and > + * options:lb_force_snat_ip=router_ip. */ > + od->lb_force_snat_router_ip = true; > + } else { > + od->lb_force_snat_router_ip = false; > + > + /* Check if 'lb_force_snat_ip' is configured with a set of > + * IP address(es). */ > + if (get_force_snat_ip(od, "lb", &od->lb_force_snat_addrs)) { > + if (od->lb_force_snat_addrs.n_ipv4_addrs) { > + snat_ip_add(od, od->lb_force_snat_addrs.ipv4_addrs[0].addr_s, > + NULL); > + } > + if (od->lb_force_snat_addrs.n_ipv6_addrs) { > + snat_ip_add(od, od->lb_force_snat_addrs.ipv6_addrs[0].addr_s, > + NULL); > + } > } > } > > @@ -8953,6 +8968,64 @@ build_lrouter_force_snat_flows(struct hmap *lflows, > struct ovn_datapath *od, > ds_destroy(&actions); > } > > +static void > +build_lrouter_force_snat_flows_op(struct ovn_port *op, > + struct hmap *lflows, > + struct ds *match, struct ds *actions) > +{ > + if (!op->nbrp || !op->peer || !op->od->lb_force_snat_router_ip) { > + return; > + } > + > + if (op->lrp_networks.n_ipv4_addrs) { > + ds_clear(match); > + ds_clear(actions); > + > + /* Higher priority rules to force SNAT with the router port ip. > + * This only takes effect when the packet has already been > + * load balanced once. */ > + ds_put_format(match, "flags.force_snat_for_lb == 1 && ip4 && " > + "outport == %s", op->json_key); > + ds_put_format(actions, "ct_snat(%s);", > + op->lrp_networks.ipv4_addrs[0].addr_s); > + ovn_lflow_add(lflows, op->od, S_ROUTER_OUT_SNAT, 110, > + ds_cstr(match), ds_cstr(actions)); > + if (op->lrp_networks.n_ipv4_addrs > 2) { > + static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); > + VLOG_WARN_RL(&rl, "Logical router port %s is configured with " > + "multiple IPv4 addresses. Only the first " > + "IP [%s] is considered as SNAT for load " > + "balancer", op->json_key, > + op->lrp_networks.ipv4_addrs[0].addr_s); > + } > + } > + > + /* op->lrp_networks.ipv6_addrs will always have LLA and that will be > + * last in the list. So add the flows only if n_ipv6_addrs > 1. */ > + if (op->lrp_networks.n_ipv6_addrs > 1) { > + ds_clear(match); > + ds_clear(actions); > + > + /* Higher priority rules to force SNAT with the router port ip. > + * This only takes effect when the packet has already been > + * load balanced once. */ > + ds_put_format(match, "flags.force_snat_for_lb == 1 && ip6 && " > + "outport == %s", op->json_key); > + ds_put_format(actions, "ct_snat(%s);", > + op->lrp_networks.ipv6_addrs[0].addr_s); > + ovn_lflow_add(lflows, op->od, S_ROUTER_OUT_SNAT, 110, > + ds_cstr(match), ds_cstr(actions)); > + if (op->lrp_networks.n_ipv6_addrs > 2) { > + static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5); > + VLOG_WARN_RL(&rl, "Logical router port %s is configured with " > + "multiple IPv6 addresses. Only the first " > + "IP [%s] is considered as SNAT for load " > + "balancer", op->json_key, > + op->lrp_networks.ipv6_addrs[0].addr_s); > + } > + } > +} > + > static void > build_lrouter_bfd_flows(struct hmap *lflows, struct ovn_port *op) > { > @@ -11503,6 +11576,8 @@ build_lswitch_and_lrouter_iterate_by_op(struct > ovn_port *op, > &lsi->match, &lsi->actions); > build_lrouter_ipv4_ip_input(op, lsi->lflows, > &lsi->match, &lsi->actions); > + build_lrouter_force_snat_flows_op(op, lsi->lflows, &lsi->match, > + &lsi->actions); > } > > static void > diff --git a/ovn-nb.xml b/ovn-nb.xml > index a94918bb63..b0a4adffe5 100644 > --- a/ovn-nb.xml > +++ b/ovn-nb.xml > @@ -1936,16 +1936,29 @@ > </column> > <column name="options" key="lb_force_snat_ip"> > <p> > - If set, indicates a set of IP addresses to use to force SNAT a > packet > - that has already been load-balanced in the gateway router. When > - multiple gateway routers are configured, a packet can potentially > - enter any of the gateway routers, get DNATted as part of the load- > - balancing and eventually reach the logical switch port. > - For the return traffic to go back to the same gateway router (for > - unDNATing), the packet needs a SNAT in the first place. This can > be > - achieved by setting the above option with a gateway specific set of > - IP addresses. This option may have exactly one IPv4 and/or one IPv6 > - address on it, separated by a space character. > + If set, this option can take two possible type of values. Either > + a set of IP addresses or the string value - <code>router_ip</code>. > + </p> > + > + <p> > + If a set of IP addresses are configured, it indicates to use to > + force SNAT a packet that has already been load-balanced in the > + gateway router. When multiple gateway routers are configured, a > + packet can potentially enter any of the gateway routers, get > + DNATted as part of the load-balancing and eventually reach the > + logical switch port. For the return traffic to go back to the > + same gateway router (for unDNATing), the packet needs a SNAT in the > + first place. This can be achieved by setting the above option with > + a gateway specific set of IP addresses. This option may have > exactly > + one IPv4 and/or one IPv6 address on it, separated by a space > + character. > + </p> > + > + <p> > + If it is configured with the value <code>router_ip</code>, then > + the load balanced packet is SNATed with the IP of router port > + (attached to the gateway router) selected as the destination after > + taking the routing decision. > </p> > </column> > <column name="options" key="mcast_relay" type='{"type": "boolean"}'> > diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at > index 64a7880677..e4831aea9b 100644 > --- a/tests/ovn-northd.at > +++ b/tests/ovn-northd.at > @@ -2520,3 +2520,82 @@ check ovn-sbctl set chassis hv1 > other_config:port-up-notif=true > wait_row_count nb:Logical_Switch_Port 1 up=false name=lsp1 > > AT_CLEANUP > + > +AT_SETUP([ovn -- lb_force_snat_ip for Gateway Routers]) > +ovn_start > + > +check ovn-nbctl ls-add sw0 > +check ovn-nbctl ls-add sw1 > + > +# Create a logical router and attach both logical switches > +check ovn-nbctl lr-add lr0 > +check ovn-nbctl lrp-add lr0 lr0-sw0 00:00:00:00:ff:01 10.0.0.1/24 > +check ovn-nbctl lsp-add sw0 sw0-lr0 > +check ovn-nbctl lsp-set-type sw0-lr0 router > +check ovn-nbctl lsp-set-addresses sw0-lr0 00:00:00:00:ff:01 > +check ovn-nbctl lsp-set-options sw0-lr0 router-port=lr0-sw0 > + > +check ovn-nbctl lrp-add lr0 lr0-sw1 00:00:00:00:ff:02 20.0.0.1/24 > +check ovn-nbctl lsp-add sw1 sw1-lr0 > +check ovn-nbctl lsp-set-type sw1-lr0 router > +check ovn-nbctl lsp-set-addresses sw1-lr0 00:00:00:00:ff:02 > +check ovn-nbctl lsp-set-options sw1-lr0 router-port=lr0-sw1 > + > +check ovn-nbctl ls-add public > +check ovn-nbctl lrp-add lr0 lr0-public 00:00:20:20:12:13 172.168.0.100/24 > +check ovn-nbctl lsp-add public public-lr0 > +check ovn-nbctl lsp-set-type public-lr0 router > +check ovn-nbctl lsp-set-addresses public-lr0 router > +check ovn-nbctl lsp-set-options public-lr0 router-port=lr0-public > + > +check ovn-nbctl set logical_router lr0 options:chassis=ch1 > + > +ovn-sbctl dump-flows lr0 > lr0flows > +AT_CAPTURE_FILE([lr0flows]) > + > +AT_CHECK([grep "lr_out_snat" lr0flows | grep force_snat_for_lb | sort], [0], > [dnl > +]) > + > +check ovn-nbctl --wait=sb set logical_router lr0 > options:lb_force_snat_ip="20.0.0.4 aef0::4" > + > +ovn-sbctl dump-flows lr0 > lr0flows > +AT_CAPTURE_FILE([lr0flows]) > + > +AT_CHECK([grep "lr_out_snat" lr0flows | grep force_snat_for_lb | sort], [0], > [dnl > + table=1 (lr_out_snat ), priority=100 , > match=(flags.force_snat_for_lb == 1 && ip4), action=(ct_snat(20.0.0.4);) > + table=1 (lr_out_snat ), priority=100 , > match=(flags.force_snat_for_lb == 1 && ip6), action=(ct_snat(aef0::4);) > +]) > + > +check ovn-nbctl --wait=sb set logical_router lr0 > options:lb_force_snat_ip="router_ip" > + > +ovn-sbctl dump-flows lr0 > lr0flows > +AT_CAPTURE_FILE([lr0flows]) > + > +AT_CHECK([grep "lr_out_snat" lr0flows | grep force_snat_for_lb | sort], [0], > [dnl > + table=1 (lr_out_snat ), priority=110 , > match=(flags.force_snat_for_lb == 1 && ip4 && outport == "lr0-public"), > action=(ct_snat(172.168.0.100);) > + table=1 (lr_out_snat ), priority=110 , > match=(flags.force_snat_for_lb == 1 && ip4 && outport == "lr0-sw0"), > action=(ct_snat(10.0.0.1);) > + table=1 (lr_out_snat ), priority=110 , > match=(flags.force_snat_for_lb == 1 && ip4 && outport == "lr0-sw1"), > action=(ct_snat(20.0.0.1);) > +]) > + > +check ovn-nbctl --wait=sb remove logical_router lr0 options chassis > + > +ovn-sbctl dump-flows lr0 > lr0flows > +AT_CAPTURE_FILE([lr0flows]) > + > +AT_CHECK([grep "lr_out_snat" lr0flows | grep force_snat_for_lb | sort], [0], > [dnl > +]) > + > +check ovn-nbctl set logical_router lr0 options:chassis=ch1 > +check ovn-nbctl --wait=sb add logical_router_port lr0-sw1 networks > "bef0\:\:1/64" > + > +ovn-sbctl dump-flows lr0 > lr0flows > +AT_CAPTURE_FILE([lr0flows]) > + > +AT_CHECK([grep "lr_out_snat" lr0flows | grep force_snat_for_lb | sort], [0], > [dnl > + table=1 (lr_out_snat ), priority=110 , > match=(flags.force_snat_for_lb == 1 && ip4 && outport == "lr0-public"), > action=(ct_snat(172.168.0.100);) > + table=1 (lr_out_snat ), priority=110 , > match=(flags.force_snat_for_lb == 1 && ip4 && outport == "lr0-sw0"), > action=(ct_snat(10.0.0.1);) > + table=1 (lr_out_snat ), priority=110 , > match=(flags.force_snat_for_lb == 1 && ip4 && outport == "lr0-sw1"), > action=(ct_snat(20.0.0.1);) > + table=1 (lr_out_snat ), priority=110 , > match=(flags.force_snat_for_lb == 1 && ip6 && outport == "lr0-sw1"), > action=(ct_snat(bef0::1);) > +]) > + > +AT_CLEANUP >
LGTM Acked-by: Mark Gray <[email protected]> _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
