On 18/02/2021 17:26, Numan Siddique wrote: > 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.
Let me rephrase. Is there a use case in which IP should be specified? However, thinking about it more, I think I have answered myself, it could be that if a link had multiple IPs, you would want to specify which IP it should take. > > 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 mailing list >>>> [email protected] >>>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev >>>> >>> >> >> _______________________________________________ >> dev mailing list >> [email protected] >> https://mail.openvswitch.org/mailman/listinfo/ovs-dev >> > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
