[ovs-dev] [PATCH ovn] Fix tcp_reset action handling
Lorenzo Bianconi
lorenzo.bianconi at redhat.com
Mon Feb 10 13:21:56 UTC 2020
>
> From: Numan Siddique <numans at ovn.org>
>
> The current handling of tcp_reset, has few issues.
>
> 1. The IP and TCP checksum of the packet injected by ovn-controller is wrong.
> 2. The ack tcp flag is not set.
> 3. If there are load balancers configured, the tcp reset packet is sent to the
> conntrack, which results in packet getting dropped in the subsequent upcalls
> by ovs-vswitchd.
>
> This patch fixes these issues. In ovn-northd lflows are added to skip sending
> the tcp reset packets to conntrack.
>
> Reported-by: Tim Rozet <trozet at redhat.com>
> Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=1795790
Thanks for fixing this :)
Acked-by: Lorenzo Bianconi <lorenzo.bianconi at redhat.com>
>
> Signed-off-by: Numan Siddique <numans at ovn.org>
> ---
> controller/pinctrl.c | 78 +++++++++++++++++------------------
> northd/ovn-northd.c | 12 ++++--
> tests/ovn.at | 20 ++++-----
> tests/system-ovn.at | 98 ++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 153 insertions(+), 55 deletions(-)
>
> diff --git a/controller/pinctrl.c b/controller/pinctrl.c
> index a35c73af4..09b0f7bf7 100644
> --- a/controller/pinctrl.c
> +++ b/controller/pinctrl.c
> @@ -300,6 +300,19 @@ static void svc_monitors_run(struct rconn *swconn,
> OVS_REQUIRES(pinctrl_mutex);
> static void svc_monitors_wait(long long int svc_monitors_next_run_time);
>
> +static void pinctrl_compose_ipv4(struct dp_packet *packet,
> + struct eth_addr eth_src,
> + struct eth_addr eth_dst, ovs_be32 ipv4_src,
> + ovs_be32 ipv4_dst, uint8_t ip_proto,
> + uint8_t ttl, uint16_t ip_payload_len);
> +static void pinctrl_compose_ipv6(struct dp_packet *packet,
> + struct eth_addr eth_src,
> + struct eth_addr eth_dst,
> + struct in6_addr *ipv6_src,
> + struct in6_addr *ipv6_dst,
> + uint8_t ip_proto, uint8_t ttl,
> + uint16_t ip_payload_len);
> +
> COVERAGE_DEFINE(pinctrl_drop_put_mac_binding);
> COVERAGE_DEFINE(pinctrl_drop_buffered_packets_map);
> COVERAGE_DEFINE(pinctrl_drop_controller_event);
> @@ -911,57 +924,40 @@ pinctrl_handle_tcp_reset(struct rconn *swconn, const struct flow *ip_flow,
> struct dp_packet packet;
>
> dp_packet_use_stub(&packet, packet_stub, sizeof packet_stub);
> - dp_packet_clear(&packet);
> packet.packet_type = htonl(PT_ETH);
> -
> - struct eth_header *eh = dp_packet_put_zeros(&packet, sizeof *eh);
> - eh->eth_dst = ip_flow->dl_dst;
> - eh->eth_src = ip_flow->dl_src;
> -
> if (get_dl_type(ip_flow) == htons(ETH_TYPE_IPV6)) {
> - struct ip6_hdr *nh = dp_packet_put_zeros(&packet, sizeof *nh);
> -
> - eh->eth_type = htons(ETH_TYPE_IPV6);
> - dp_packet_set_l3(&packet, nh);
> - nh->ip6_vfc = 0x60;
> - nh->ip6_nxt = IPPROTO_TCP;
> - nh->ip6_plen = htons(TCP_HEADER_LEN);
> - packet_set_ipv6(&packet, &ip_flow->ipv6_src, &ip_flow->ipv6_dst,
> - ip_flow->nw_tos, ip_flow->ipv6_label, 255);
> + pinctrl_compose_ipv6(&packet, ip_flow->dl_src, ip_flow->dl_dst,
> + (struct in6_addr *)&ip_flow->ipv6_src,
> + (struct in6_addr *)&ip_flow->ipv6_dst,
> + IPPROTO_TCP, 63, TCP_HEADER_LEN);
> } else {
> - struct ip_header *nh = dp_packet_put_zeros(&packet, sizeof *nh);
> -
> - eh->eth_type = htons(ETH_TYPE_IP);
> - dp_packet_set_l3(&packet, nh);
> - nh->ip_ihl_ver = IP_IHL_VER(5, 4);
> - nh->ip_tot_len = htons(IP_HEADER_LEN + TCP_HEADER_LEN);
> - nh->ip_proto = IPPROTO_TCP;
> - nh->ip_frag_off = htons(IP_DF);
> - packet_set_ipv4(&packet, ip_flow->nw_src, ip_flow->nw_dst,
> - ip_flow->nw_tos, 255);
> + pinctrl_compose_ipv4(&packet, ip_flow->dl_src, ip_flow->dl_dst,
> + ip_flow->nw_src, ip_flow->nw_dst,
> + IPPROTO_TCP, 63, TCP_HEADER_LEN);
> }
>
> struct tcp_header *th = dp_packet_put_zeros(&packet, sizeof *th);
> - struct tcp_header *tcp_in = dp_packet_l4(pkt_in);
> dp_packet_set_l4(&packet, th);
> - th->tcp_ctl = TCP_CTL(TCP_RST, 5);
> - if (ip_flow->tcp_flags & htons(TCP_ACK)) {
> - th->tcp_seq = tcp_in->tcp_ack;
> - } else {
> - uint32_t tcp_seq, ack_seq, tcp_len;
> + th->tcp_dst = ip_flow->tp_src;
> + th->tcp_src = ip_flow->tp_dst;
>
> - tcp_seq = ntohl(get_16aligned_be32(&tcp_in->tcp_seq));
> - tcp_len = TCP_OFFSET(tcp_in->tcp_ctl) * 4;
> - ack_seq = tcp_seq + dp_packet_l4_size(pkt_in) - tcp_len;
> - put_16aligned_be32(&th->tcp_ack, htonl(ack_seq));
> - put_16aligned_be32(&th->tcp_seq, 0);
> - }
> - packet_set_tcp_port(&packet, ip_flow->tp_dst, ip_flow->tp_src);
> + th->tcp_ctl = htons((5 << 12) | TCP_RST | TCP_ACK);
> + put_16aligned_be32(&th->tcp_seq, 0);
>
> - if (ip_flow->vlans[0].tci & htons(VLAN_CFI)) {
> - eth_push_vlan(&packet, htons(ETH_TYPE_VLAN_8021Q),
> - ip_flow->vlans[0].tci);
> + struct tcp_header *tcp_in = dp_packet_l4(pkt_in);
> + uint32_t tcp_seq = ntohl(get_16aligned_be32(&tcp_in->tcp_seq)) + 1;
> + put_16aligned_be32(&th->tcp_ack, htonl(tcp_seq));
> +
> + uint32_t csum;
> + if (get_dl_type(ip_flow) == htons(ETH_TYPE_IPV6)) {
> + csum = packet_csum_pseudoheader6(dp_packet_l3(&packet));
> + } else {
> + csum = packet_csum_pseudoheader(dp_packet_l3(&packet));
> }
> + csum = csum_continue(csum, th, dp_packet_size(&packet) -
> + ((const unsigned char *)th -
> + (const unsigned char *)dp_packet_eth(&packet)));
> + th->tcp_csum = csum_finish(csum);
>
> set_actions_and_enqueue_msg(swconn, &packet, md, userdata);
> dp_packet_uninit(&packet);
> diff --git a/northd/ovn-northd.c b/northd/ovn-northd.c
> index 6e113b35c..42ae5c61f 100644
> --- a/northd/ovn-northd.c
> +++ b/northd/ovn-northd.c
> @@ -4638,11 +4638,11 @@ build_pre_acls(struct ovn_datapath *od, struct hmap *lflows)
> * unreachable packets. */
> ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_ACL, 110,
> "nd || nd_rs || nd_ra || icmp4.type == 3 || "
> - "icmp6.type == 1 || (tcp && tcp.flags == 4)",
> + "icmp6.type == 1 || (tcp && tcp.flags == 20)",
> "next;");
> ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_ACL, 110,
> "nd || nd_rs || nd_ra || icmp4.type == 3 || "
> - "icmp6.type == 1 || (tcp && tcp.flags == 4)",
> + "icmp6.type == 1 || (tcp && tcp.flags == 20)",
> "next;");
>
> /* Ingress and Egress Pre-ACL Table (Priority 100).
> @@ -4750,9 +4750,13 @@ build_pre_lb(struct ovn_datapath *od, struct hmap *lflows,
> {
> /* Do not send ND packets to conntrack */
> ovn_lflow_add(lflows, od, S_SWITCH_IN_PRE_LB, 110,
> - "nd || nd_rs || nd_ra", "next;");
> + "nd || nd_rs || nd_ra || icmp4.type == 3 ||"
> + "icmp6.type == 1 || (tcp && tcp.flags == 20)",
> + "next;");
> ovn_lflow_add(lflows, od, S_SWITCH_OUT_PRE_LB, 110,
> - "nd || nd_rs || nd_ra", "next;");
> + "nd || nd_rs || nd_ra || icmp4.type == 3 ||"
> + "icmp6.type == 1 || (tcp && tcp.flags == 20)",
> + "next;");
>
> /* Do not send service monitor packets to conntrack. */
> char *svc_check_match = xasprintf("eth.src == %s", svc_monitor_mac);
> diff --git a/tests/ovn.at b/tests/ovn.at
> index 091351c0e..8e18b24ec 100644
> --- a/tests/ovn.at
> +++ b/tests/ovn.at
> @@ -11681,8 +11681,8 @@ test_tcp_syn_packet() {
> 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
> + local tcp_rst_ttl=3f
> + local reply=${eth_src}${eth_dst}08004500002800004000${tcp_rst_ttl}06${exp_ip_chksum}${ipv4_dst}${ipv4_src}${tcp_dport}${tcp_sport}000000000000000250140000${exp_tcp_rst_chksum}0000
> echo $reply >> vif$inport.expected
>
> as hv$hv ovs-appctl netdev-dummy/receive vif$inport $packet
> @@ -11738,9 +11738,9 @@ test_ip_packet 31 3 000000000031 000000000012 $(ip_to_hex 192 168 1 31) $(ip_to_
>
> test_ipv6_packet 11 1 000000000011 000000000021 fe80000000000000020001fffe000001 fe80000000000000020001fffe000002 6183
>
> -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
> +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 b85f 70e4
> +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 b85f 70e4
> +test_tcp_syn_packet 31 3 000000000031 000000000012 $(ip_to_hex 192 168 1 31) $(ip_to_hex 192 168 1 12) 0000 8b40 3039 0000 b854 70d9
>
> for i in 1 2 3; do
> OVN_CHECK_PACKETS([hv$i/vif${i}1-tx.pcap], [vif${i}1.expected])
> @@ -12814,8 +12814,8 @@ test_tcp_syn_packet() {
> local ip_ttl=ff
> local packet=${eth_dst}${eth_src}08004500002800004000${ip_ttl}06${ip_chksum}${ipv4_src}${ip_router}${tcp_sport}${tcp_dport}000000010000000050027210${tcp_chksum}0000
>
> - local tcp_rst_ttl=fe
> - local reply=${eth_src}${eth_dst}08004500002800004000${tcp_rst_ttl}06${exp_ip_chksum}${ip_router}${ipv4_src}${tcp_dport}${tcp_sport}000000000000000150040000${exp_tcp_rst_chksum}0000
> + local tcp_rst_ttl=3e
> + local reply=${eth_src}${eth_dst}08004500002800004000${tcp_rst_ttl}06${exp_ip_chksum}${ip_router}${ipv4_src}${tcp_dport}${tcp_sport}000000000000000250140000${exp_tcp_rst_chksum}0000
> echo $reply >> vif$inport.expected
>
> as hv$hv ovs-appctl netdev-dummy/receive vif$inport $packet
> @@ -12835,7 +12835,7 @@ test_tcp6_packet() {
> local ip6_hdr=60000000001406ff${ipv6_src}${ipv6_router}
> local packet=${eth_dst}${eth_src}86dd${ip6_hdr}${tcp_sport}${tcp_dport}000000010000000050027210${tcp_chksum}0000
>
> - local reply=${eth_src}${eth_dst}86dd60000000001406fe${ipv6_router}${ipv6_src}${tcp_dport}${tcp_sport}000000000000000150040000${exp_tcp_rst_chksum}0000
> + local reply=${eth_src}${eth_dst}86dd600000000014063e${ipv6_router}${ipv6_src}${tcp_dport}${tcp_sport}000000000000000250140000${exp_tcp_rst_chksum}0000
> echo $reply >> vif$inport.expected
>
> as hv$hv ovs-appctl netdev-dummy/receive vif$inport $packet
> @@ -12901,9 +12901,9 @@ test_ip_packet 1 1 000000000001 00000000ff01 $(ip_to_hex 192 168 1 1) $(ip_to_he
> test_ip6_packet 1 1 000000000001 00000000ff01 20010db8000100000000000000000011 20010db8000100000000000000000001 11 0015 dbb8303900155bac6b646f65206676676e6d66720a 0104 d570
> OVN_CHECK_PACKETS([hv1/vif1-tx.pcap], [vif1.expected])
>
> -test_tcp_syn_packet 2 2 000000000002 00000000ff02 $(ip_to_hex 192 168 2 1) $(ip_to_hex 192 168 2 254) 0000 8b40 3039 0000 7bae 4486
> +test_tcp_syn_packet 2 2 000000000002 00000000ff02 $(ip_to_hex 192 168 2 1) $(ip_to_hex 192 168 2 254) 0000 8b40 3039 0000 b680 6e05
> test_ip6_packet 2 2 000000000002 00000000ff02 20010db8000200000000000000000011 20010db8000200000000000000000001 84 0004 01020304 0103 627e
> -test_tcp6_packet 2 2 000000000002 00000000ff02 20010db8000200000000000000000011 20010db8000200000000000000000001 8b40 3039 0000 4486
> +test_tcp6_packet 2 2 000000000002 00000000ff02 20010db8000200000000000000000011 20010db8000200000000000000000001 8b40 3039 0000 98cd
> OVN_CHECK_PACKETS([hv2/vif2-tx.pcap], [vif2.expected])
>
> OVN_CLEANUP([hv1], [hv2])
> diff --git a/tests/system-ovn.at b/tests/system-ovn.at
> index 662d71251..53da910cb 100644
> --- a/tests/system-ovn.at
> +++ b/tests/system-ovn.at
> @@ -3623,3 +3623,101 @@ as
> OVS_TRAFFIC_VSWITCHD_STOP(["/failed to query port patch-.*/d
> /connection dropped.*/d"])
> AT_CLEANUP
> +
> +
> +AT_SETUP([ovn -- ACL reject - TCP reset])
> +AT_SKIP_IF([test $HAVE_NC = no])
> +AT_KEYWORDS([lb])
> +
> +ovn_start
> +
> +OVS_TRAFFIC_VSWITCHD_START()
> +ADD_BR([br-int])
> +
> +# Set external-ids in br-int needed for ovn-controller
> +ovs-vsctl \
> + -- set Open_vSwitch . external-ids:system-id=hv1 \
> + -- set Open_vSwitch . external-ids:ovn-remote=unix:$ovs_base/ovn-sb/ovn-sb.sock \
> + -- set Open_vSwitch . external-ids:ovn-encap-type=geneve \
> + -- set Open_vSwitch . external-ids:ovn-encap-ip=169.0.0.1 \
> + -- set bridge br-int fail-mode=secure other-config:disable-in-band=true
> +
> +# Start ovn-controller
> +start_daemon ovn-controller
> +
> +ovn-nbctl ls-add sw0
> +
> +ovn-nbctl lsp-add sw0 sw0-p1
> +ovn-nbctl lsp-set-addresses sw0-p1 "50:54:00:00:00:03 10.0.0.3 aef0::3"
> +ovn-nbctl lsp-set-port-security sw0-p1 "50:54:00:00:00:03 10.0.0.3 aef0::3"
> +
> +ovn-nbctl lsp-add sw0 sw0-p2
> +ovn-nbctl lsp-set-addresses sw0-p2 "50:54:00:00:00:04 10.0.0.4 aef0::4"
> +ovn-nbctl lsp-set-port-security sw0-p2 "50:54:00:00:00:04 10.0.0.4 aef0::4"
> +
> +ovn-nbctl --log acl-add sw0 from-lport 1000 "inport == \"sw0-p1\" && tcp && tcp.dst == 80" reject
> +ovn-nbctl --log acl-add sw0 from-lport 1000 "inport == \"sw0-p2\" && ip6 && tcp && tcp.dst == 80" reject
> +
> +OVN_POPULATE_ARP
> +ovn-nbctl --wait=hv sync
> +
> +ADD_NAMESPACES(sw0-p1)
> +ADD_VETH(sw0-p1, sw0-p1, br-int, "10.0.0.3/24", "50:54:00:00:00:03", \
> + "10.0.0.1")
> +
> +ADD_NAMESPACES(sw0-p2)
> +ADD_VETH(sw0-p2, sw0-p2, br-int, "10.0.0.4/24", "50:54:00:00:00:04", \
> + "10.0.0.1")
> +
> +NS_CHECK_EXEC([sw0-p1], [ip a a aef0::3/64 dev sw0-p1], [0])
> +NS_CHECK_EXEC([sw0-p2], [ip a a aef0::4/64 dev sw0-p2], [0])
> +
> +# Capture packets in sw0-p1.
> +NS_CHECK_EXEC([sw0-p1], [tcpdump -n -c 2 -i sw0-p1 tcp port 80 > sw0-p1-ip4.pcap &], [0])
> +sleep 1
> +
> +NS_CHECK_EXEC([sw0-p1], [nc 10.0.0.4 80], [1], [],
> +[dnl
> +Ncat: Connection refused.
> +])
> +
> +OVS_WAIT_UNTIL([
> + total=`cat sw0-p1-ip4.pcap | wc -l`
> + echo "total = $total"
> + test "${total}" = "2"
> +])
> +
> +# Without this sleep, test case fails intermittently.
> +sleep 3
> +
> +NS_CHECK_EXEC([sw0-p2], [tcpdump -n -c 2 -i sw0-p2 tcp port 80 > sw0-p2-ip6.pcap &], [0])
> +
> +sleep 1
> +
> +NS_CHECK_EXEC([sw0-p2], [nc -6 aef0::3 80], [1], [],
> +[dnl
> +Ncat: Connection refused.
> +])
> +
> +OVS_WAIT_UNTIL([
> + total=`cat sw0-p2-ip6.pcap | wc -l`
> + echo "total = $total"
> + test "${total}" = "2"
> +])
> +
> +OVS_APP_EXIT_AND_WAIT([ovn-controller])
> +
> +as ovn-sb
> +OVS_APP_EXIT_AND_WAIT([ovsdb-server])
> +
> +as ovn-nb
> +OVS_APP_EXIT_AND_WAIT([ovsdb-server])
> +
> +as northd
> +OVS_APP_EXIT_AND_WAIT([ovn-northd])
> +
> +as
> +OVS_TRAFFIC_VSWITCHD_STOP(["/failed to query port patch-.*/d
> +/connection dropped.*/d"])
> +
> +AT_CLEANUP
> --
> 2.24.1
>
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