On Wed, Feb 17, 2021 at 7:37 PM Mark Gray <mark.d.g...@redhat.com> wrote: > > Thanks Numan, some suggestions below!
Hi Mark G, Thanks for the review. PSB for a few comments. > > On 09/02/2021 18:44, num...@ovn.org wrote: > > From: Numan Siddique <num...@ovn.org> > > > > 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 chosen as 'outport' > > in lr_in_ip_routing stage. > > It almost feels like this should be the default behaviour? Can you please elaborate more ? You mean ideally CMS should set - router_ip ? > > > > 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 <tro...@redhat.com> > > Signed-off-by: Numan Siddique <num...@ovn.org> > > --- > > northd/ovn-northd.8.xml | 35 ++++++++++++++++++ > > northd/ovn-northd.c | 66 ++++++++++++++++++++++++++++++++-- > > tests/ovn-northd.at | 79 +++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 177 insertions(+), 3 deletions(-) > > > > diff --git a/northd/ovn-northd.8.xml b/northd/ovn-northd.8.xml > > index 70065a36d9..27b28aff93 100644 > > --- a/northd/ovn-northd.8.xml > > +++ b/northd/ovn-northd.8.xml > > Should 'ovn-nb.xml' also be updated? Great catch. I totally missed it. > > > @@ -3653,6 +3653,32 @@ 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 router port IP configured. > > maybe rephrase to "is the IP configured on the router port." Ack. done > > > + 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. > > Should we log this condition? Ack. I have added the log for this in v2. > > > + </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 > > @@ -3660,6 +3686,9 @@ 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 > > @@ -3673,14 +3702,18 @@ 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 > > @@ -3689,7 +3722,9 @@ 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 db6572a62b..ece158b71e 100644 > > --- a/northd/ovn-northd.c > > +++ b/northd/ovn-northd.c > > @@ -622,6 +622,7 @@ 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; > > @@ -721,6 +722,17 @@ init_nat_entries(struct ovn_datapath *od) > > snat_ip_add(od, od->lb_force_snat_addrs.ipv6_addrs[0].addr_s, > > NULL); > > } > > + } else { > > + 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; > > + } > > } > > > > if (!od->nbr->n_nat) { > > @@ -8365,9 +8377,12 @@ get_force_snat_ip(struct ovn_datapath *od, const > > char *key_type, > > } > > > > if (!extract_ip_address(addresses, laddrs)) { > > - static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1); > > - VLOG_WARN_RL(&rl, "bad ip %s in options of router "UUID_FMT"", > > - addresses, UUID_ARGS(&od->key)); > > + if (strcmp(addresses, "router_ip") || strcmp(key_type, "lb")) { > > Also, probably good to check or assert 'key_type' for NULL even though, > currently, all callers of get_force_snat_ip() cant pass a NULL value. In v2, (which I'll submit now), I'm not modifying this function at all. Also if "key_type' is NULL, then the code above this , which is ---- char *key = xasprintf("%s_force_snat_ip", key_type); const char *addresses = smap_get(&od->nbr->options, key); ----- 'addresses' will be NULL and hence we will not hit this condition. > > + static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1); > > + VLOG_WARN_RL(&rl, "bad ip %s in options of router "UUID_FMT"", > > + addresses, UUID_ARGS(&od->key)); > > + } > > + > > return false; > > I think finding an IP or 'router_ip' should be the successful case and > not finding them should be unsuccessful. However, this would change the > logic for callers. Or maybe the name of this function could change and > another function to check for router_ip could be added. What do you think? Ok. I get your point. My only reason to modify the function - get_force_snat_ip() was not to not log a warning if 'router_ip' is set. Ideally this function should be called if the option is a set of IP address(es). So in v2, I've not modified this function. But instead I first check if lb_force_snat_ip is configured with 'router_ip' or not. I felt there is probably no need for a function just for that. > > > } > > > > @@ -8943,6 +8958,48 @@ 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, > > General musing that doesn't need to be addressed here. I wonder should > we have a macro definition for priorities for logical flows? I'm not too sure. I think we could. But we will end up with lots of macros. Please check out the v2. Thanks Numan > > > + ds_cstr(match), ds_cstr(actions)); > > + } > > + > > + /* 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)); > > + } > > +} > > + > > static void > > build_lrouter_bfd_flows(struct hmap *lflows, struct ovn_port *op) > > { > > @@ -11278,6 +11335,7 @@ build_lrouter_nat_defrag_and_lb(struct ovn_datapath > > *od, > > "dnat"); > > } > > } > > + > > if (lb_force_snat_ip) { > > if (od->lb_force_snat_addrs.n_ipv4_addrs) { > > build_lrouter_force_snat_flows(lflows, od, "4", > > @@ -11490,6 +11548,8 @@ 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/tests/ovn-northd.at b/tests/ovn-northd.at > > index 7240e22baf..fd03b1fb66 100644 > > --- a/tests/ovn-northd.at > > +++ b/tests/ovn-northd.at > > @@ -2443,3 +2443,82 @@ 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 > > > > _______________________________________________ > dev mailing list > d...@openvswitch.org > https://mail.openvswitch.org/mailman/listinfo/ovs-dev > _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev