[ovs-dev] [PATCH ovn] northd: fix ttl exceeded with FIP
Numan Siddique
numans at ovn.org
Tue Nov 16 03:16:24 UTC 2021
On Thu, Nov 11, 2021 at 3:44 PM Mark Michelson <mmichels at redhat.com> wrote:
>
> 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; "
Hi Lorenzo,
Can you please explain why the ttl is changed to 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
Since the ttl is changed to 254, I think the flow description here
https://github.com/ovn-org/ovn/blob/main/northd/ovn-northd.8.xml#L2758
# L2758 should also be updated right ?
You don't have to submit another version. Before applying I wanted to be sure.
Thanks
Numan
> > == <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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