[ovs-dev] [PATCH ovn] northd: fix ttl exceeded with FIP
Mark Michelson
mmichels at redhat.com
Thu Nov 11 20:43:45 UTC 2021
Hi Lorenzo, the patch looks good to me.
Acked-by: Mark Michelson <mmichels at redhat.com>
On 11/10/21 17:35, Lorenzo Bianconi wrote:
> Properly manage ttl exceeded ICMP error messages when traffic is
> directed to a FIP. The issue can be verified running traceroute from an
> external device to a FIP:
> $traceroute -I -z 1 -n <FIP>
>
> Fix ttl exceeded priority respect to ping responder.
>
> Related bz: https://bugzilla.redhat.com/show_bug.cgi?id=2006349
>
> Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi at redhat.com>
> ---
> northd/northd.c | 59 ++++++++++++++++++++++++-----------------
> northd/ovn-northd.8.xml | 2 +-
> tests/ovn.at | 10 +++----
> 3 files changed, 41 insertions(+), 30 deletions(-)
>
> diff --git a/northd/northd.c b/northd/northd.c
> index 1e8a3457c..ce962cdc4 100644
> --- a/northd/northd.c
> +++ b/northd/northd.c
> @@ -11798,6 +11798,7 @@ build_ipv6_input_flows_for_lrouter_port(
> }
>
> /* ICMPv6 time exceeded */
> + struct ds ip_ds = DS_EMPTY_INITIALIZER;
> for (int i = 0; i < op->lrp_networks.n_ipv6_addrs; i++) {
> /* skip link-local address */
> if (in6_is_lla(&op->lrp_networks.ipv6_addrs[i].network)) {
> @@ -11806,7 +11807,13 @@ build_ipv6_input_flows_for_lrouter_port(
>
> ds_clear(match);
> ds_clear(actions);
> -
> + ds_clear(&ip_ds);
> + if (op->od->n_l3dgw_ports && op->od->l3dgw_ports[0] == op) {
> + ds_put_cstr(&ip_ds, "ip6.dst <-> ip6.src");
> + } else {
> + ds_put_format(&ip_ds, "ip6.dst = ip6.src; ip6.src = %s",
> + op->lrp_networks.ipv6_addrs[i].addr_s);
> + }
> ds_put_format(match,
> "inport == %s && ip6 && "
> "ip6.src == %s/%d && "
> @@ -11817,20 +11824,18 @@ build_ipv6_input_flows_for_lrouter_port(
> ds_put_format(actions,
> "icmp6 {"
> "eth.dst <-> eth.src; "
> - "ip6.dst = ip6.src; "
> - "ip6.src = %s; "
> - "ip.ttl = 255; "
> + "%s ; ip.ttl = 254; "
> "icmp6.type = 3; /* Time exceeded */ "
> "icmp6.code = 0; /* TTL exceeded in transit */ "
> - "next; };",
> - op->lrp_networks.ipv6_addrs[i].addr_s);
> - ovn_lflow_add_with_hint__(lflows, op->od, S_ROUTER_IN_IP_INPUT, 40,
> - ds_cstr(match), ds_cstr(actions), NULL,
> - copp_meter_get(COPP_ICMP6_ERR,
> - op->od->nbr->copp,
> - meter_groups),
> - &op->nbrp->header_);
> + "outport = %s; flags.loopback = 1; output; };",
> + ds_cstr(&ip_ds), op->json_key);
> + ovn_lflow_add_with_hint__(lflows, op->od, S_ROUTER_IN_IP_INPUT,
> + 100, ds_cstr(match), ds_cstr(actions), NULL,
> + copp_meter_get(COPP_ICMP6_ERR, op->od->nbr->copp,
> + meter_groups),
> + &op->nbrp->header_);
> }
> + ds_destroy(&ip_ds);
> }
>
> }
> @@ -11930,10 +11935,17 @@ build_lrouter_ipv4_ip_input(struct ovn_port *op,
> build_lrouter_bfd_flows(lflows, op, meter_groups);
>
> /* ICMP time exceeded */
> + struct ds ip_ds = DS_EMPTY_INITIALIZER;
> for (int i = 0; i < op->lrp_networks.n_ipv4_addrs; i++) {
> ds_clear(match);
> ds_clear(actions);
> -
> + ds_clear(&ip_ds);
> + if (op->od->n_l3dgw_ports && op->od->l3dgw_ports[0] == op) {
> + ds_put_cstr(&ip_ds, "ip4.dst <-> ip4.src");
> + } else {
> + ds_put_format(&ip_ds, "ip4.dst = ip4.src; ip4.src = %s",
> + op->lrp_networks.ipv4_addrs[i].addr_s);
> + }
> ds_put_format(match,
> "inport == %s && ip4 && "
> "ip.ttl == {0, 1} && !ip.later_frag", op->json_key);
> @@ -11942,18 +11954,17 @@ build_lrouter_ipv4_ip_input(struct ovn_port *op,
> "eth.dst <-> eth.src; "
> "icmp4.type = 11; /* Time exceeded */ "
> "icmp4.code = 0; /* TTL exceeded in transit */ "
> - "ip4.dst = ip4.src; "
> - "ip4.src = %s; "
> - "ip.ttl = 255; "
> - "next; };",
> - op->lrp_networks.ipv4_addrs[i].addr_s);
> - ovn_lflow_add_with_hint__(lflows, op->od, S_ROUTER_IN_IP_INPUT, 40,
> - ds_cstr(match), ds_cstr(actions), NULL,
> - copp_meter_get(COPP_ICMP4_ERR,
> - op->od->nbr->copp,
> - meter_groups),
> - &op->nbrp->header_);
> + "%s ; ip.ttl = 254; "
> + "outport = %s; flags.loopback = 1; output; };",
> + ds_cstr(&ip_ds), op->json_key);
> + ovn_lflow_add_with_hint__(lflows, op->od, S_ROUTER_IN_IP_INPUT,
> + 100, ds_cstr(match), ds_cstr(actions), NULL,
> + copp_meter_get(COPP_ICMP4_ERR, op->od->nbr->copp,
> + meter_groups),
> + &op->nbrp->header_);
> +
> }
> + ds_destroy(&ip_ds);
>
> /* ARP reply. These flows reply to ARP requests for the router's own
> * IP address. */
> diff --git a/northd/ovn-northd.8.xml b/northd/ovn-northd.8.xml
> index fb67395e3..aa51aeb24 100644
> --- a/northd/ovn-northd.8.xml
> +++ b/northd/ovn-northd.8.xml
> @@ -2742,7 +2742,7 @@ nd.tll = <var>external_mac</var>;
> <li>
> <p>
> ICMP time exceeded. For each router port <var>P</var>, whose IP
> - address is <var>A</var>, a priority-40 flow with match <code>inport
> + address is <var>A</var>, a priority-100 flow with match <code>inport
> == <var>P</var> && ip.ttl == {0, 1} &&
> !ip.later_frag</code> matches packets whose TTL has expired, with the
> following actions to send an ICMP time exceeded reply for IPv4 and
> diff --git a/tests/ovn.at b/tests/ovn.at
> index 51e0dae0b..ae832918c 100644
> --- a/tests/ovn.at
> +++ b/tests/ovn.at
> @@ -7203,7 +7203,7 @@ test_ipv4_icmp_request() {
> shift; shift
>
> # Use ttl to exercise section 4.2.2.9 of RFC1812
> - local ip_ttl=01
> + local ip_ttl=02
> local icmp_id=5fbf
> local icmp_seq=0001
> local icmp_data=$(seq 1 56 | xargs printf "%02x")
> @@ -7230,12 +7230,12 @@ l1_ip=$(ip_to_hex 192 168 1 2)
> l2_ip=$(ip_to_hex 172 16 1 2)
>
> # Ping router ip address that is on same subnet as the logical port
> -test_ipv4_icmp_request 1 000000010203 0000000102f1 $l1_ip $rtr_l1_ip 0000 8510 02ff 8d10
> -test_ipv4_icmp_request 2 000000010204 0000000102f2 $l2_ip $rtr_l2_ip 0000 8510 02ff 8d10
> +test_ipv4_icmp_request 1 000000010203 0000000102f1 $l1_ip $rtr_l1_ip 0000 8510 03ff 8d10
> +test_ipv4_icmp_request 2 000000010204 0000000102f2 $l2_ip $rtr_l2_ip 0000 8510 03ff 8d10
>
> # Ping router ip address that is on the other side of the logical ports
> -test_ipv4_icmp_request 1 000000010203 0000000102f1 $l1_ip $rtr_l2_ip 0000 8510 02ff 8d10
> -test_ipv4_icmp_request 2 000000010204 0000000102f2 $l2_ip $rtr_l1_ip 0000 8510 02ff 8d10
> +test_ipv4_icmp_request 1 000000010203 0000000102f1 $l1_ip $rtr_l2_ip 0000 8510 03ff 8d10
> +test_ipv4_icmp_request 2 000000010204 0000000102f2 $l2_ip $rtr_l1_ip 0000 8510 03ff 8d10
>
>
> echo "---------NB dump-----"
>
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