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selftests/net: test tcp connection load balancing

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Verify that TCP connections use both routes when connecting multiple
times to a remote service over a two nexthop multipath route.

Use socat to create the connections. Use tc prio + tc filter to
count routes taken, counting SYN packets across the two egress
devices. Also verify that the saddr matches that of the device.

To avoid flaky tests when testing inherently randomized behavior,
set a low bar and pass if even a single SYN is observed on each
device.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20250424143549.669426-4-willemdebruijn.kernel@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Willem de Bruijn
2025-04-24 10:35:20 -04:00
committed by Paolo Abeni
parent 65e9024643
commit 4d0dac499b
2 changed files with 143 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

120
tools/testing/selftests/net/fib_tests.sh
View File

@@ -11,7 +11,7 @@ TESTS="unregister down carrier nexthop suppress ipv6_notify ipv4_notify \
ipv6_rt ipv4_rt ipv6_addr_metric ipv4_addr_metric ipv6_route_metrics \
ipv4_route_metrics ipv4_route_v6_gw rp_filter ipv4_del_addr \
ipv6_del_addr ipv4_mangle ipv6_mangle ipv4_bcast_neigh fib6_gc_test \
ipv4_mpath_list ipv6_mpath_list"
ipv4_mpath_list ipv6_mpath_list ipv4_mpath_balance ipv6_mpath_balance"
VERBOSE=0
PAUSE_ON_FAIL=no
@@ -1085,6 +1085,35 @@ route_setup()
set +e
}
forwarding_cleanup()
{
cleanup_ns $ns3
route_cleanup
}
# extend route_setup with an ns3 reachable through ns2 over both devices
forwarding_setup()
{
forwarding_cleanup
route_setup
setup_ns ns3
ip link add veth5 netns $ns3 type veth peer name veth6 netns $ns2
ip -netns $ns3 link set veth5 up
ip -netns $ns2 link set veth6 up
ip -netns $ns3 -4 addr add dev veth5 172.16.105.1/24
ip -netns $ns2 -4 addr add dev veth6 172.16.105.2/24
ip -netns $ns3 -4 route add 172.16.100.0/22 via 172.16.105.2
ip -netns $ns3 -6 addr add dev veth5 2001:db8:105::1/64 nodad
ip -netns $ns2 -6 addr add dev veth6 2001:db8:105::2/64 nodad
ip -netns $ns3 -6 route add 2001:db8:101::/33 via 2001:db8:105::2
}
# assumption is that basic add of a single path route works
# otherwise just adding an address on an interface is broken
ipv6_rt_add()
@@ -2600,6 +2629,93 @@ ipv6_mpath_list_test()
route_cleanup
}
tc_set_flower_counter__saddr_syn() {
tc_set_flower_counter $1 $2 $3 "src_ip $4 ip_proto tcp tcp_flags 0x2"
}
ip_mpath_balance_dep_check()
{
if [ ! -x "$(command -v socat)" ]; then
echo "socat command not found. Skipping test"
return 1
fi
if [ ! -x "$(command -v jq)" ]; then
echo "jq command not found. Skipping test"
return 1
fi
}
ip_mpath_balance() {
local -r ipver=$1
local -r daddr=$2
local -r num_conn=20
for i in $(seq 1 $num_conn); do
ip netns exec $ns3 socat $ipver TCP-LISTEN:8000 STDIO >/dev/null &
sleep 0.02
echo -n a | ip netns exec $ns1 socat $ipver STDIO TCP:$daddr:8000
done
local -r syn0="$(tc_get_flower_counter $ns1 veth1)"
local -r syn1="$(tc_get_flower_counter $ns1 veth3)"
local -r syns=$((syn0+syn1))
[ "$VERBOSE" = "1" ] && echo "multipath: syns seen: ($syn0,$syn1)"
[[ $syns -ge $num_conn ]] && [[ $syn0 -gt 0 ]] && [[ $syn1 -gt 0 ]]
}
ipv4_mpath_balance_test()
{
echo
echo "IPv4 multipath load balance test"
ip_mpath_balance_dep_check || return 1
forwarding_setup
$IP route add 172.16.105.1 \
nexthop via 172.16.101.2 \
nexthop via 172.16.103.2
ip netns exec $ns1 \
sysctl -q -w net.ipv4.fib_multipath_hash_policy=1
tc_set_flower_counter__saddr_syn $ns1 4 veth1 172.16.101.1
tc_set_flower_counter__saddr_syn $ns1 4 veth3 172.16.103.1
ip_mpath_balance -4 172.16.105.1
log_test $? 0 "IPv4 multipath loadbalance"
forwarding_cleanup
}
ipv6_mpath_balance_test()
{
echo
echo "IPv6 multipath load balance test"
ip_mpath_balance_dep_check || return 1
forwarding_setup
$IP route add 2001:db8:105::1\
nexthop via 2001:db8:101::2 \
nexthop via 2001:db8:103::2
ip netns exec $ns1 \
sysctl -q -w net.ipv6.fib_multipath_hash_policy=1
tc_set_flower_counter__saddr_syn $ns1 6 veth1 2001:db8:101::1
tc_set_flower_counter__saddr_syn $ns1 6 veth3 2001:db8:103::1
ip_mpath_balance -6 "[2001:db8:105::1]"
log_test $? 0 "IPv6 multipath loadbalance"
forwarding_cleanup
}
################################################################################
# usage
@@ -2683,6 +2799,8 @@ do
fib6_gc_test|ipv6_gc) fib6_gc_test;;
ipv4_mpath_list) ipv4_mpath_list_test;;
ipv6_mpath_list) ipv6_mpath_list_test;;
ipv4_mpath_balance) ipv4_mpath_balance_test;;
ipv6_mpath_balance) ipv6_mpath_balance_test;;
help) echo "Test names: $TESTS"; exit 0;;
esac

24
tools/testing/selftests/net/lib.sh
View File

@@ -270,6 +270,30 @@ tc_rule_handle_stats_get()
.options.actions[0].stats$selector"
}
# attach a qdisc with two children match/no-match and a flower filter to match
tc_set_flower_counter() {
local -r ns=$1
local -r ipver=$2
local -r dev=$3
local -r flower_expr=$4
tc -n $ns qdisc add dev $dev root handle 1: prio bands 2 \
priomap 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
tc -n $ns qdisc add dev $dev parent 1:1 handle 11: pfifo
tc -n $ns qdisc add dev $dev parent 1:2 handle 12: pfifo
tc -n $ns filter add dev $dev parent 1: protocol ipv$ipver \
flower $flower_expr classid 1:2
}
tc_get_flower_counter() {
local -r ns=$1
local -r dev=$2
tc -n $ns -j -s qdisc show dev $dev handle 12: | jq .[0].packets
}
ret_set_ksft_status()
{
local ksft_status=$1; shift