[ovs-dev] [PATCH ovn v4] ovn-controller: Avoid infinite replying for TCP/ICMP connection reset messages

Mohammad Heib mheib at redhat.com
Tue Nov 30 09:23:14 UTC 2021


When the ovn controller receives an ip packet that targets a lport that has ACL
rule to reject ip packets, the controller will reply with TCP_RST or icmp4/6 unreachable packet
to notify the sender that the destination is not available.

In turn, the receiver host will receive the notification packet and handle it as a normal IP packet
and if the receiver host is part of the same logical-switch/port-group or has IP reject ACL rule
it will send TCP_RST or icmp4/6 unreachable packet replying to the TCP_RST or icmp4/6 unreachable
packet we received and here we will enter to an infinity loop of replying about replying which
will consume high CPU.

To avoid such scenarios this patch proposes to drop/ignore TCP_RST or icmp4/6 unreachable packets
that received on lport that has  IP reject ACL rules.

Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=1934011
Fixes: 64f8c9e9f ("actions: Add a new OVN action - reject {}.")
Signed-off-by: Mohammad Heib <mheib at redhat.com>
---
 controller/pinctrl.c |  29 +++++++++++
 tests/ovn.at         | 113 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 142 insertions(+)

diff --git a/controller/pinctrl.c b/controller/pinctrl.c
index ae5320e09..0d443c150 100644
--- a/controller/pinctrl.c
+++ b/controller/pinctrl.c
@@ -1933,11 +1933,40 @@ pinctrl_handle_sctp_abort(struct rconn *swconn, const struct flow *ip_flow,
     dp_packet_uninit(&packet);
 }
 
+static bool
+pinctrl_handle_reject_ignore_pkt(const struct flow *ip_flow,
+                                 struct dp_packet *pkt_in)
+{
+    if (ip_flow->nw_proto == IPPROTO_TCP) {
+        struct tcp_header *th = dp_packet_l4(pkt_in);
+        if (!th || (TCP_FLAGS(th->tcp_ctl) & TCP_RST)) {
+            return true;
+        }
+    } else {
+        if (is_icmpv4(ip_flow, NULL)) {
+            struct icmp_header *ih = dp_packet_l4(pkt_in);
+            if (!ih || (ih->icmp_type == ICMP4_DST_UNREACH)) {
+                return true;
+            }
+        } else if (is_icmpv6(ip_flow, NULL)) {
+            struct icmp6_data_header *ih = dp_packet_l4(pkt_in);
+            if (!ih || (ih->icmp6_base.icmp6_type == ICMP6_DST_UNREACH)) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
 static void
 pinctrl_handle_reject(struct rconn *swconn, const struct flow *ip_flow,
                       struct dp_packet *pkt_in,
                       const struct match *md, struct ofpbuf *userdata)
 {
+    if (pinctrl_handle_reject_ignore_pkt(ip_flow, pkt_in)) {
+        return;
+    }
+
     if (ip_flow->nw_proto == IPPROTO_TCP) {
         pinctrl_handle_tcp_reset(swconn, ip_flow, pkt_in, md, userdata, true);
     } else if (ip_flow->nw_proto == IPPROTO_SCTP) {
diff --git a/tests/ovn.at b/tests/ovn.at
index 7a7ae0da6..a4ed03041 100644
--- a/tests/ovn.at
+++ b/tests/ovn.at
@@ -14223,6 +14223,119 @@ OVN_CLEANUP([hv1], [hv2], [hv3])
 AT_CLEANUP
 ])
 
+OVN_FOR_EACH_NORTHD([
+AT_SETUP([ACL Reject ping pong])
+AT_KEYWORDS([ACL Reject ping pong])
+ovn_start
+
+send_icmp6_packet() {
+    local inport=$1 hv=$2 eth_src=$3 eth_dst=$4 ipv6_src=$5 ipv6_dst=$6
+
+    local ip6_hdr=6000000000083aff${ipv6_src}${ipv6_dst}
+    local packet=${eth_dst}${eth_src}86dd${ip6_hdr}8000dcb662f00001
+
+    as hv$hv ovs-appctl netdev-dummy/receive hv${hv}-vif$inport $packet
+}
+
+send_icmp_packet() {
+    local inport=$1 hv=$2 eth_src=$3 eth_dst=$4 ipv4_src=$5 ipv4_dst=$6 ip_chksum=$7 data=$8
+    shift 8
+
+    local ip_ttl=ff
+    local ip_len=001c
+    local packet=${eth_dst}${eth_src}08004500${ip_len}00004000${ip_ttl}01${ip_chksum}${ipv4_src}${ipv4_dst}${data}
+    as hv$hv ovs-appctl netdev-dummy/receive hv${hv}-vif$inport $packet
+}
+
+net_add n1
+
+sim_add hv1
+as hv1
+ovs-vsctl add-br br-phys
+ovn_attach n1 br-phys 192.168.0.1
+ovs-vsctl -- add-port br-int hv1-vif1 -- \
+    set interface hv1-vif1 external-ids:iface-id=sw0-p1 \
+    options:tx_pcap=hv1/vif1-tx.pcap \
+    options:rxq_pcap=hv1/vif1-rx.pcap \
+    ofport-request=1
+
+sim_add hv2
+as hv2
+ovs-vsctl add-br br-phys
+ovn_attach n1 br-phys 192.168.0.2
+ovs-vsctl -- add-port br-int hv2-vif1 -- \
+    set interface hv2-vif1 external-ids:iface-id=sw0-p2 \
+    options:tx_pcap=hv2/vif1-tx.pcap \
+    options:rxq_pcap=hv2/vif1-rx.pcap \
+    ofport-request=1
+
+ovn-nbctl ls-add sw0
+
+check ovn-nbctl lsp-add sw0 sw0-p1
+check ovn-nbctl lsp-set-addresses sw0-p1 "50:54:00:00:00:03 10.0.0.3 1000::3"
+check ovn-nbctl lsp-set-port-security sw0-p1 "50:54:00:00:00:03 10.0.0.3 1000::3"
+
+check ovn-nbctl lsp-add sw0 sw0-p2
+check ovn-nbctl lsp-set-addresses sw0-p2 "50:54:00:00:00:04 10.0.0.4 1000::4"
+check ovn-nbctl lsp-set-port-security sw0-p2 "50:54:00:00:00:04 10.0.0.4 1000::4"
+
+check ovn-nbctl acl-add sw0 to-lport 1002 ip reject
+
+OVN_POPULATE_ARP
+
+wait_for_ports_up
+ovn-nbctl --wait=hv sync
+
+ovn-sbctl dump-flows sw0 > sw0-flows
+AT_CAPTURE_FILE([sw0-flows])
+
+AT_CHECK([grep -E 'ls_(in|out)_acl' sw0-flows |grep reject| sed 's/table=../table=??/' | sort], [0], [dnl
+  table=??(ls_out_acl         ), priority=2002 , match=(ip), action=(reg0 = 0; reject { /* eth.dst <-> eth.src; ip.dst <-> ip.src; is implicit. */ outport <-> inport; next(pipeline=ingress,table=22); };)
+])
+
+
+eth_src=505400000003
+eth_dst=505400000004
+ip_src=$(ip_to_hex 10 0 0 3)
+ip_dst=$(ip_to_hex 10 0 0 4)
+ipv6_src=10000000000000000000000000000003
+ipv6_dst=10000000000000000000000000000004
+
+send_icmp_packet 1 1 $eth_src $eth_dst $ip_src $ip_dst c4c9 0000000000000000000000
+send_icmp6_packet 1 1 $eth_src $eth_dst $ipv6_src $ipv6_dst
+sleep 2
+
+# Get total number of ipv4 packets that received on ovs
+
+# sender side
+flow=$(as hv1 ovs-ofctl dump-flows br-int table=44 | grep priority=2002|grep ip,metadata=0x1)
+n_pkts="$(echo $flow|awk -F',' '{ print $4 }'|awk -F'=' '{ print $2 }')"
+check test $n_pkts -eq 1
+
+# receiver side
+flow=$(as hv2 ovs-ofctl dump-flows br-int table=44 | grep priority=2002|grep ip,metadata=0x1)
+n_pkts="$(echo $flow|awk -F',' '{ print $4 }'|awk -F'=' '{ print $2 }')"
+check test $n_pkts -eq 1
+
+# Get total number of ipv6 packets that received on ovs
+
+# sender side
+flow=$(as hv1 ovs-ofctl dump-flows br-int table=44 | grep priority=2002|grep ipv6,metadata=0x1)
+n_pkts="$(echo $flow|awk -F',' '{ print $4 }'|awk -F'=' '{ print $2 }')"
+check test $n_pkts -eq 1
+
+
+# receiver side
+flow=$(as hv2 ovs-ofctl dump-flows br-int table=44 | grep priority=2002|grep ipv6,metadata=0x1)
+n_pkts="$(echo $flow|awk -F',' '{ print $4 }'|awk -F'=' '{ print $2 }')"
+check test $n_pkts -eq 1
+
+
+OVN_CLEANUP([hv1], [hv2])
+AT_CLEANUP
+])
+
+
 OVN_FOR_EACH_NORTHD([
 AT_SETUP([Port Groups])
 AT_KEYWORDS([ovnpg])
-- 
2.26.3



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