On Thu, Feb 18, 2021 at 9:15 PM Mark Gray <[email protected]> wrote: > > On 18/02/2021 14:30, Numan Siddique wrote: > > On Wed, Feb 17, 2021 at 7:37 PM Mark Gray <[email protected]> wrote: > >> > >> Thanks Numan, some suggestions below! > > > > Hi Mark G, > > > > Thanks for the review. > > > > PSB for a few comments. > > > >> > >> On 09/02/2021 18:44, [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 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 ? > > I was thinking that it could just be lb_force_snat_ip=true (default to > remote_ip)?
You mean 'router_ip' ? If it is 'true' then, IMHO, it is not clear with what IP to snat with. Since lb_force_snat_ip can take other IP addresses (which is the present case), I am not sure if mixing bool/string would be clear enough for the user. Let me know if you think it is obvious that it will be router ip if set to true. Thanks Numan > > > > > >>> > >>> 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 | 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 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