[ovs-dev] [PATCH v4] bfd: Support overlay BFD

Thu Jul 23 13:50:24 UTC 2020

On Wed, Jul 22, 2020 at 1:41 PM Yifeng Sun <pkusunyifeng at gmail.com> wrote:
>
> Current OVS intercepts and processes all BFD packets, thus VM-2-VM
> BFD packets get lost and the recipient VM never sees them.
>
> This patch fixes it by only intercepting and processing BFD packets
> destined to a configured BFD instance, and other BFD packets are made
> available to the OVS flow table for forwarding.
>
> This patch keeps BFD's backward compatibility.
>
> VMWare-BZ: 2579326
s/VMWare/VMware
s/2579326/#2579326/

> Signed-off-by: Yifeng Sun <pkusunyifeng at gmail.com>
> ---
> v1->v2: Add test by William's suggestion.
> v2->v3: Fix BFD config, thanks William.
> v3->v4: Test will fail at second run, fixed it.
>
>  lib/bfd.c               | 16 +++++++++++++---
>  tests/system-traffic.at | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  vswitchd/vswitch.xml    |  7 +++++++
>  3 files changed, 64 insertions(+), 3 deletions(-)
>
> diff --git a/lib/bfd.c b/lib/bfd.c
> index cc8c6857afa4..3c965699ace3 100644
> --- a/lib/bfd.c
> +++ b/lib/bfd.c
> @@ -149,6 +149,9 @@ BUILD_ASSERT_DECL(BFD_PACKET_LEN == sizeof(struct msg));
>  #define FLAGS_MASK 0x3f
>  #define DEFAULT_MULT 3
>
> +#define BFD_DEFAULT_SRC_IP 0xA9FE0101 /* 169.254.1.1 */
> +#define BFD_DEFAULT_DST_IP 0xA9FE0100 /* 169.254.1.0 */
> +
>  struct bfd {
>      struct hmap_node node;        /* In 'all_bfds'. */
>      uint32_t disc;                /* bfd.LocalDiscr. Key in 'all_bfds' hmap. */
> @@ -457,9 +460,9 @@ bfd_configure(struct bfd *bfd, const char *name, const struct smap *cfg,
>                           &bfd->rmt_eth_dst);
>
>      bfd_lookup_ip(smap_get_def(cfg, "bfd_src_ip", ""),
> -                  htonl(0xA9FE0101) /* 169.254.1.1 */, &bfd->ip_src);
> +                  htonl(BFD_DEFAULT_SRC_IP), &bfd->ip_src);
>      bfd_lookup_ip(smap_get_def(cfg, "bfd_dst_ip", ""),
> -                  htonl(0xA9FE0100) /* 169.254.1.0 */, &bfd->ip_dst);
> +                  htonl(BFD_DEFAULT_DST_IP), &bfd->ip_dst);
>
>      forwarding_if_rx = smap_get_bool(cfg, "forwarding_if_rx", false);
>      if (bfd->forwarding_if_rx != forwarding_if_rx) {
> @@ -674,7 +677,14 @@ bfd_should_process_flow(const struct bfd *bfd_, const struct flow *flow,
>          memset(&wc->masks.nw_proto, 0xff, sizeof wc->masks.nw_proto);
>          if (flow->nw_proto == IPPROTO_UDP
>              && !(flow->nw_frag & FLOW_NW_FRAG_LATER)
> -            && tp_dst_equals(flow, BFD_DEST_PORT, wc)) {
> +            && tp_dst_equals(flow, BFD_DEST_PORT, wc)
> +            && (bfd->ip_src == htonl(BFD_DEFAULT_SRC_IP)
> +                || bfd->ip_src == flow->nw_dst)) {
> +
> +            if (bfd->ip_src == flow->nw_dst) {
> +                memset(&wc->masks.nw_dst, 0xffffffff, sizeof wc->masks.nw_dst);
> +            }
> +
>              bool check_tnl_key;
>
>              atomic_read_relaxed(&bfd->check_tnl_key, &check_tnl_key);
> diff --git a/tests/system-traffic.at b/tests/system-traffic.at
> index 2a0fbadff4a1..ea72f155782f 100644
> --- a/tests/system-traffic.at
> +++ b/tests/system-traffic.at
> @@ -6289,3 +6289,47 @@ OVS_WAIT_UNTIL([cat p2.pcap | egrep "0x0050: *0000 *0000 *5002 *2000 *b85e *0000
>
>  OVS_TRAFFIC_VSWITCHD_STOP
>  AT_CLEANUP
> +
> +AT_SETUP([bfd - BFD overlay])
> +OVS_CHECK_GENEVE()
> +
> +OVS_TRAFFIC_VSWITCHD_START()
> +
> +AT_CHECK([ovs-vsctl -- set bridge br0 other-config:hwaddr=\"f2:ff:00:00:00:01\"])
> +ADD_BR([br-underlay], [set bridge br-underlay other-config:hwaddr=\"ee:09:e0:4d:bf:31\"])
> +
> +AT_CHECK([ovs-ofctl add-flow br0 "actions=normal"])
> +AT_CHECK([ovs-ofctl add-flow br-underlay "actions=normal"])
> +
> +ADD_NAMESPACES(at_ns0)
> +
> +dnl Set up underlay link from host into the namespace using veth pair.
> +ADD_VETH(p0, at_ns0, br-underlay, "172.16.180.105/24", 4e:12:5d:6c:74:3d)
> +AT_CHECK([ip addr add dev br-underlay "172.16.180.106/24"])
> +AT_CHECK([ip link set dev br-underlay up])
> +
> +dnl Set up tunnel endpoints on OVS outside the namespace.
> +ADD_OVS_TUNNEL([geneve], [br0], [at_gnv0], [172.16.180.105], [192.168.10.100/24],
> +                [options:packet_type=ptap])
> +AT_CHECK([ovs-vsctl -- set Interface at_gnv0 ofport_request=1])
> +AT_CHECK([ovs-vsctl -- set Interface at_gnv0 bfd:enable=true bfd:bfd_src_ip="172.16.180.106"])
> +
> +dnl Certain Linux distributions, like CentOS, have default iptable rules
> +dnl to reject input traffic from br-underlay. Here we add a rule to walk
> +dnl around it.
> +iptables -I INPUT 1 -i br-underlay -j ACCEPT
> +on_exit 'iptables -D INPUT 1'
> +
> +dnl Firstly, test normal BFD packet.
> +ovs-ofctl -O OpenFlow13 packet-out br-underlay "in_port=1 packet=ee09e04dbf314e125d6c743d080045c00066ea4e400040118e83ac10b469ac10b46a356e17c10052cb5500806558000000000023200000018ad232b919c4080045c0003400000000ff11fa03ac10b469ac10b46ac0000ec80020000020800318035cd00e00000000000f4240000f424000000000 actions=NORMAL"
> +dnl Next we test overlay BFD packet.
> +ovs-ofctl -O OpenFlow13 packet-out br-underlay "in_port=1 packet=ee09e04dbf314e125d6c743d08004500005b2558400040115445ac10b469ac10b46a6b1017c1004722c1024065580000000001048001001803005254009d0b6d5254000c89840800450000210e22400040119688c0a80a68c0a80a6995cd0ec8000dd342746573740a actions=NORMAL"
> +
> +ovs-dpctl dump-flows > datapath-flows.txt
> +dnl BFD packet was handled by BFD flow. Ipv4.dst is matched.
> +AT_FAIL_IF([cat datapath-flows.txt | egrep "tunnel\(.*,src=172.16.180.105,dst=172.16.180.106,.*,eth\(\),eth_type\(0x0800\),ipv4\(dst=172.16.180.106,proto=17,.*\),udp\(dst=3784\), .*, actions:userspace\(pid=.*,slow_path\(bfd\)\)" 2>&1 1>/dev/null])

please run
$ make check-kmod TESTSUITEFLAGS='-d -k BFD'
the test pass but there is no bfd packet in the datapath-flows.txt
$ grep bfd tests/system-kmod-testsuite.dir/131/datapath-flows.txt

William