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netdev-offload-tc: Fix offload of tunnel key tp_src.
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There is no TCA_TUNNEL_KEY_ENC_SRC_PORT in the kernel, so the offload
should not be attempted if OVS_TUNNEL_KEY_ATTR_TP_SRC is requested
by OVS.  Current code just ignores the attribute in the tunnel(set())
action leading to a flow mismatch and potential incorrect datapath
behavior:

  |tc(handler21)|DBG|tc flower compare failed action compare
  ...
  Action 0 mismatch:
  - Expected Action:
  00000010 01 00 00 00 00 00 00 00-00 00 00 00 00 ff 00 11
  00000020 c0 5b 17 c1 00 40 00 00-0a 01 00 6d 0a 01 01 12
  00000050 08 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00000060 01 02 80 01 00 18 00 0b-00 00 00 00 00 00 00 00
  ...
 - Received Action:
  00000010 01 00 00 00 00 00 00 00-00 00 00 00 00 ff 00 11
  00000020 00 00 17 c1 00 40 00 00-0a 01 00 6d 0a 01 01 12
  00000050 08 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00000060 01 02 80 01 00 18 00 0b-00 00 00 00 00 00 00 00
  ...

In the tc_action dump above we can see the difference on the second
line.  The action dumped from a kernel is missing 'c0 5b' - source
port for a tunnel(set()) action on the second line.

Removing the field from the tc_action_encap structure entirely to
avoid any potential confusion.

Note: In general, the source port number in the tunnel(set()) action
is not particularly useful for most tunnels, because they may just
ignore the value.  Specs for Geneve and VXLAN suggest using a value
based on the headers of the inner packet as a source port.
In vast majority of scenarios the source port doesn't actually end
up in the action itself.
Having a mismatch between the userspace and TC leads to constant
revalidation of the flow and warnings in the log.

Adding a test case that demonstrates a scenario where the issue
occurs - bridging of two tunnels.

Fixes: 8f283af ("netdev-tc-offloads: Implement netdev flow put using tc interface")
Reported-at: https://mail.openvswitch.org/pipermail/ovs-discuss/2023-October/052744.html
Reported-by: Vladislav Odintsov <[email protected]>
Acked-by: Eelco Chaudron <[email protected]>
Signed-off-by: Ilya Maximets <[email protected]>
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@igsilya
igsilya committed Dec 1, 2023
1 parent c8d4946 commit 634bedf
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Showing 3 changed files with 80 additions and 2 deletions.
4 changes: 3 additions & 1 deletion lib/netdev-offload-tc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1627,7 +1627,9 @@ parse_put_flow_set_action(struct tc_flower *flower, struct tc_action *action,
}
break;
case OVS_TUNNEL_KEY_ATTR_TP_SRC: {
action->encap.tp_src = nl_attr_get_be16(tun_attr);
/* There is no corresponding attribute in TC. */
VLOG_DBG_RL(&rl, "unsupported tunnel key attribute TP_SRC");
return EOPNOTSUPP;
}
break;
case OVS_TUNNEL_KEY_ATTR_TP_DST: {
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3 changes: 2 additions & 1 deletion lib/tc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -213,7 +213,8 @@ enum nat_type {
struct tc_action_encap {
bool id_present;
ovs_be64 id;
ovs_be16 tp_src;
/* ovs_be16 tp_src; Could have been here, but there is no
* TCA_TUNNEL_KEY_ENC_ attribute for it in the kernel. */
ovs_be16 tp_dst;
uint8_t tos;
uint8_t ttl;
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75 changes: 75 additions & 0 deletions tests/system-traffic.at
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Original file line number Diff line number Diff line change
Expand Up @@ -903,6 +903,81 @@ ovs-pcap p0.pcap
AT_CHECK([ovs-pcap p0.pcap | grep -Eq "^[[[:xdigit:]]]{24}86dd60000000003a1140fc000000000000000000000000000100fc000000000000000000000000000001[[[:xdigit:]]]{4}17c1003a[[[:xdigit:]]]{4}0000655800000000fffffffffffffa163e949d8008060001080006040001[[[:xdigit:]]]{12}0a0000f40000000000000a0000fe$"])
AT_CLEANUP

AT_SETUP([datapath - bridging two geneve tunnels])
OVS_CHECK_TUNNEL_TSO()
OVS_CHECK_GENEVE()

OVS_TRAFFIC_VSWITCHD_START()
ADD_BR([br-underlay-0])
ADD_BR([br-underlay-1])

ADD_NAMESPACES(at_ns0)
ADD_NAMESPACES(at_ns1)

dnl Set up underlay link from host into the namespaces using veth pairs.
ADD_VETH(p0, at_ns0, br-underlay-0, "172.31.1.1/24")
AT_CHECK([ip addr add dev br-underlay-0 "172.31.1.100/24"])
AT_CHECK([ip link set dev br-underlay-0 up])

ADD_VETH(p1, at_ns1, br-underlay-1, "172.31.2.1/24")
AT_CHECK([ip addr add dev br-underlay-1 "172.31.2.100/24"])
AT_CHECK([ip link set dev br-underlay-1 up])

dnl Set up two OVS tunnel endpoints in a root namespace and two native
dnl linux devices inside the test namespaces.
dnl
dnl ns_gnv0 | ns_gnv1
dnl ip: 10.1.1.1/24 | ip: 10.1.1.2/24
dnl remote_ip: 172.31.1.100 | remote_ip: 172.31.2.100
dnl | | |
dnl | | |
dnl p0 | p1
dnl ip: 172.31.1.1/24 | ip: 172.31.2.1/24
dnl | NS0 | NS1 |
dnl ---------|------------------------+------------------|--------------------
dnl | |
dnl br-underlay-0: br-underlay-1:
dnl ip: 172.31.1.100/24 ip: 172.31.2.100/24
dnl ovs-p0 ovs-p1
dnl | |
dnl | br0 |
dnl encap/decap ----- ip: 10.1.1.100/24 -- encap/decap
dnl at_gnv0
dnl at_gnv1
dnl
ADD_OVS_TUNNEL([geneve], [br0], [at_gnv0], [172.31.1.1], [10.1.1.100/24])
ADD_NATIVE_TUNNEL([geneve], [ns_gnv0], [at_ns0], [172.31.1.100], [10.1.1.1/24],
[vni 0])
ADD_OVS_TUNNEL([geneve], [br0], [at_gnv1], [172.31.2.1], [10.1.1.101/24])
ADD_NATIVE_TUNNEL([geneve], [ns_gnv1], [at_ns1], [172.31.2.100], [10.1.1.2/24],
[vni 0])

AT_CHECK([ovs-ofctl add-flow br0 "actions=normal"])
AT_CHECK([ovs-ofctl add-flow br-underlay-0 "actions=normal"])
AT_CHECK([ovs-ofctl add-flow br-underlay-1 "actions=normal"])

dnl First, check both underlays.
NS_CHECK_EXEC([at_ns0], [ping -q -c 3 -i 0.3 -W 2 172.31.1.100 | FORMAT_PING], [0], [dnl
3 packets transmitted, 3 received, 0% packet loss, time 0ms
])
NS_CHECK_EXEC([at_ns1], [ping -q -c 3 -i 0.3 -W 2 172.31.2.100 | FORMAT_PING], [0], [dnl
3 packets transmitted, 3 received, 0% packet loss, time 0ms
])

dnl Now, check the overlay with different packet sizes.
NS_CHECK_EXEC([at_ns0], [ping -q -c 3 -i 0.3 -W 2 10.1.1.2 | FORMAT_PING], [0], [dnl
3 packets transmitted, 3 received, 0% packet loss, time 0ms
])
NS_CHECK_EXEC([at_ns0], [ping -s 1600 -q -c 3 -i 0.3 -W 2 10.1.1.2 | FORMAT_PING], [0], [dnl
3 packets transmitted, 3 received, 0% packet loss, time 0ms
])
NS_CHECK_EXEC([at_ns0], [ping -s 3200 -q -c 3 -i 0.3 -W 2 10.1.1.2 | FORMAT_PING], [0], [dnl
3 packets transmitted, 3 received, 0% packet loss, time 0ms
])

OVS_TRAFFIC_VSWITCHD_STOP
AT_CLEANUP

AT_SETUP([datapath - ping over gre tunnel by simulated packets])
OVS_CHECK_TUNNEL_TSO()
OVS_CHECK_MIN_KERNEL(3, 10)
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