Whenever the acl reject rule is hit by a TCP segment send back
a TCP RST packet to close the connection using the tcp_reset action.
Moreover add add tcp_reset test case to 'ACL reject rule test'

Signed-off-by: Lorenzo Bianconi <lorenzo.bianc...@redhat.com>
---
 ovn/northd/ovn-northd.c | 14 +++++++++-----
 tests/ovn.at            | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/ovn/northd/ovn-northd.c b/ovn/northd/ovn-northd.c
index 396381049..b299703f9 100644
--- a/ovn/northd/ovn-northd.c
+++ b/ovn/northd/ovn-northd.c
@@ -2905,9 +2905,11 @@ build_pre_acls(struct ovn_datapath *od, struct hmap 
*lflows)
          * Not to do conntrack on ND and ICMP destination
          * unreachable packets. */
         ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_ACL, 110,
-                      "nd || nd_rs || nd_ra || icmp4.type == 3", "next;");
+                      "nd || nd_rs || nd_ra || icmp4.type == 3 || "
+                      "(tcp && tcp.flags == 4)", "next;");
         ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_ACL, 110,
-                      "nd || nd_rs || nd_ra || icmp4.type == 3", "next;");
+                      "nd || nd_rs || nd_ra || icmp4.type == 3 || "
+                      "(tcp && tcp.flags == 4)", "next;");
 
         /* Ingress and Egress Pre-ACL Table (Priority 100).
          *
@@ -3097,14 +3099,16 @@ build_reject_acl_rules(struct ovn_datapath *od, struct 
hmap *lflows,
     struct ds actions = DS_EMPTY_INITIALIZER;
     bool ingress = (stage == S_SWITCH_IN_ACL);
 
-    /* XXX: Treat TCP connections as "drop;" for now */
     build_acl_log(&actions, acl);
     if (extra_match->length > 0) {
         ds_put_format(&match, "(%s) && ", extra_match->string);
     }
     ds_put_format(&match, "ip && tcp && (%s)", acl->match);
-    ds_put_cstr(&actions, "/* drop */");
-    ovn_lflow_add(lflows, od, stage, acl->priority + OVN_ACL_PRI_OFFSET,
+    ds_put_format(&actions, "reg0 = 0; "
+                  "eth.dst <-> eth.src; ip4.dst <-> ip4.src; "
+                  "tcp_reset { outport <-> inport; %s };",
+                  ingress ? "output;" : "next(pipeline=ingress,table=0);");
+    ovn_lflow_add(lflows, od, stage, acl->priority + OVN_ACL_PRI_OFFSET + 10,
                   ds_cstr(&match), ds_cstr(&actions));
 
     /* IPv4 traffic */
diff --git a/tests/ovn.at b/tests/ovn.at
index 4cd3bbf9b..0f37b8892 100644
--- a/tests/ovn.at
+++ b/tests/ovn.at
@@ -9386,6 +9386,34 @@ test_ip_packet() {
     as hv$hv ovs-appctl netdev-dummy/receive vif$inport $packet
 }
 
+# test_tcp_syn_packet INPORT HV ETH_SRC ETH_DST IPV4_SRC IPV4_DST IP_CHKSUM 
TCP_SPORT TCP_DPORT TCP_CHKSUM EXP_IP_CHKSUM EXP_TCP_RST_CHKSUM
+#
+# Causes a packet to be received on INPORT of the hypervisor HV. The packet is 
an TCP syn segment with
+# ETH_SRC, ETH_DST, IPV4_SRC, IPV4_DST, IP_CHKSUM, TCP_SPORT, TCP_DPORT, 
TCP_CHKSUM  as specified.
+# EXP_IP_CHKSUM and EXP_TCP_RST_CHKSUM are the ip and tcp checksums of the tcp 
reset segment generated from ACL rule hit
+#
+# INPORT is an lport number, e.g. 11 for vif11.
+# HV is an hypervisor number
+# ETH_SRC and ETH_DST are each 12 hex digits.
+# IPV4_SRC and IPV4_DST are each 8 hex digits.
+# TCP_SPORT and TCP_DPORT are 4 hex digits.
+# IP_CHKSUM, TCP_CHKSUM, EXP_IP_CHSUM and EXP_TCP_RST_CHKSUM are each 4 hex 
digits
+test_tcp_syn_packet() {
+    local inport=$1 hv=$2 eth_src=$3 eth_dst=$4 ipv4_src=$5 ipv4_dst=$6 
ip_chksum=$7
+    local tcp_sport=$8 tcp_dport=$9 tcp_chksum=${10}
+    local exp_ip_chksum=${11} exp_tcp_rst_chksum=${12}
+    shift 12
+
+    local ip_ttl=ff
+    local 
packet=${eth_dst}${eth_src}08004500002800004000${ip_ttl}06${ip_chksum}${ipv4_src}${ipv4_dst}${tcp_sport}${tcp_dport}000000010000000050027210${tcp_chksum}0000
+
+    local tcp_rst_ttl=ff
+    local 
reply=${eth_src}${eth_dst}08004500002800004000${tcp_rst_ttl}06${exp_ip_chksum}${ipv4_dst}${ipv4_src}${tcp_dport}${tcp_sport}000000000000000150040000${exp_tcp_rst_chksum}0000
+    echo $reply >> vif$inport.expected
+
+    as hv$hv ovs-appctl netdev-dummy/receive vif$inport $packet
+}
+
 # Create hypervisors hv[123].
 # Add vif1[123] to hv1, vif2[123] to hv2, vif3[123] to hv3.
 # Add all of the vifs to a single logical switch sw0.
@@ -9432,6 +9460,10 @@ test_ip_packet 11 1 000000000011 000000000021 
$(ip_to_hex 192 168 1 11) $(ip_to_
 test_ip_packet 21 2 000000000021 000000000011 $(ip_to_hex 192 168 1 21) 
$(ip_to_hex 192 168 1 11) 0000 7d8d fcfe
 test_ip_packet 31 3 000000000031 000000000012 $(ip_to_hex 192 168 1 31) 
$(ip_to_hex 192 168 1 12) 0000 7d82 fcfe
 
+test_tcp_syn_packet 11 1 000000000011 000000000021 $(ip_to_hex 192 168 1 11) 
$(ip_to_hex 192 168 1 21) 0000 8b40 3039 0000 7d8d 4486
+test_tcp_syn_packet 21 2 000000000021 000000000011 $(ip_to_hex 192 168 1 21) 
$(ip_to_hex 192 168 1 11) 0000 8b40 3039 0000 7d8d 4486
+test_tcp_syn_packet 31 3 000000000031 000000000012 $(ip_to_hex 192 168 1 31) 
$(ip_to_hex 192 168 1 12) 0000 8b40 3039 0000 7d82 4486
+
 for i in 1 2 3; do
     OVN_CHECK_PACKETS([hv$i/vif${i}1-tx.pcap], [vif${i}1.expected])
 done
-- 
2.14.3

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