selftests: forwarding: router_mpath_hash: Add a new selftest

Add a selftest that exercises the sysctl added in the previous patches.

Test that set/get works as expected; that across seeds we eventually hit
all NHs (test_mpath_seed_*); and that a given seed keeps hitting the same
NHs even across seed changes (test_mpath_seed_stability_*).
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240607151357.421181-6-petrm@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/forwarding/Makefile

@@ -70,6 +70,7 @@ TEST_PROGS = bridge_fdb_learning_limit.sh \
 	router_broadcast.sh \
 	router_mpath_nh_res.sh \
 	router_mpath_nh.sh \
+	router_mpath_seed.sh \
 	router_multicast.sh \
 	router_multipath.sh \
 	router_nh.sh \

tools/testing/selftests/net/forwarding/router_mpath_seed.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# +-------------------------+  +-------------------------+
+# |  H1                     |  |                      H2 |
+# |               $h1 +     |  | + $h2                   |
+# |      192.0.2.1/28 |     |  | | 192.0.2.34/28         |
+# |  2001:db8:1::1/64 |     |  | | 2001:db8:3::2/64      |
+# +-------------------|-----+  +-|-----------------------+
+#                     |          |
+# +-------------------|-----+  +-|-----------------------+
+# |  R1               |     |  | |                    R2 |
+# |             $rp11 +     |  | + $rp21                 |
+# |      192.0.2.2/28       |  |   192.0.2.33/28         |
+# |  2001:db8:1::2/64       |  |   2001:db8:3::1/64      |
+# |                         |  |                         |
+# |             $rp12 +     |  | + $rp22                 |
+# |     192.0.2.17/28 |     |  | | 192.0.2.18..27/28     |
+# | 2001:db8:2::17/64 |     |  | | 2001:db8:2::18..27/64 |
+# +-------------------|-----+  +-|-----------------------+
+#                     |          |
+#                     `----------'
+
+ALL_TESTS="
+	ping_ipv4
+	ping_ipv6
+	test_mpath_seed_stability_ipv4
+	test_mpath_seed_stability_ipv6
+	test_mpath_seed_get
+	test_mpath_seed_ipv4
+	test_mpath_seed_ipv6
+"
+NUM_NETIFS=6
+source lib.sh
+
+h1_create()
+{
+	simple_if_init $h1 192.0.2.1/28 2001:db8:1::1/64
+	ip -4 route add 192.0.2.32/28 vrf v$h1 nexthop via 192.0.2.2
+	ip -6 route add 2001:db8:3::/64 vrf v$h1 nexthop via 2001:db8:1::2
+}
+
+h1_destroy()
+{
+	ip -6 route del 2001:db8:3::/64 vrf v$h1 nexthop via 2001:db8:1::2
+	ip -4 route del 192.0.2.32/28 vrf v$h1 nexthop via 192.0.2.2
+	simple_if_fini $h1 192.0.2.1/28 2001:db8:1::1/64
+}
+
+h2_create()
+{
+	simple_if_init $h2 192.0.2.34/28 2001:db8:3::2/64
+	ip -4 route add 192.0.2.0/28 vrf v$h2 nexthop via 192.0.2.33
+	ip -6 route add 2001:db8:1::/64 vrf v$h2 nexthop via 2001:db8:3::1
+}
+
+h2_destroy()
+{
+	ip -6 route del 2001:db8:1::/64 vrf v$h2 nexthop via 2001:db8:3::1
+	ip -4 route del 192.0.2.0/28 vrf v$h2 nexthop via 192.0.2.33
+	simple_if_fini $h2 192.0.2.34/28 2001:db8:3::2/64
+}
+
+router1_create()
+{
+	simple_if_init $rp11 192.0.2.2/28 2001:db8:1::2/64
+	__simple_if_init $rp12 v$rp11 192.0.2.17/28 2001:db8:2::17/64
+}
+
+router1_destroy()
+{
+	__simple_if_fini $rp12 192.0.2.17/28 2001:db8:2::17/64
+	simple_if_fini $rp11 192.0.2.2/28 2001:db8:1::2/64
+}
+
+router2_create()
+{
+	simple_if_init $rp21 192.0.2.33/28 2001:db8:3::1/64
+	__simple_if_init $rp22 v$rp21 192.0.2.18/28 2001:db8:2::18/64
+	ip -4 route add 192.0.2.0/28 vrf v$rp21 nexthop via 192.0.2.17
+	ip -6 route add 2001:db8:1::/64 vrf v$rp21 nexthop via 2001:db8:2::17
+}
+
+router2_destroy()
+{
+	ip -6 route del 2001:db8:1::/64 vrf v$rp21 nexthop via 2001:db8:2::17
+	ip -4 route del 192.0.2.0/28 vrf v$rp21 nexthop via 192.0.2.17
+	__simple_if_fini $rp22 192.0.2.18/28 2001:db8:2::18/64
+	simple_if_fini $rp21 192.0.2.33/28 2001:db8:3::1/64
+}
+
+nexthops_create()
+{
+	local i
+	for i in $(seq 10); do
+		ip nexthop add id $((1000 + i)) via 192.0.2.18 dev $rp12
+		ip nexthop add id $((2000 + i)) via 2001:db8:2::18 dev $rp12
+	done
+
+	ip nexthop add id 1000 group $(seq -s / 1001 1010) hw_stats on
+	ip nexthop add id 2000 group $(seq -s / 2001 2010) hw_stats on
+	ip -4 route add 192.0.2.32/28 vrf v$rp11 nhid 1000
+	ip -6 route add 2001:db8:3::/64 vrf v$rp11 nhid 2000
+}
+
+nexthops_destroy()
+{
+	local i
+
+	ip -6 route del 2001:db8:3::/64 vrf v$rp11 nhid 2000
+	ip -4 route del 192.0.2.32/28 vrf v$rp11 nhid 1000
+	ip nexthop del id 2000
+	ip nexthop del id 1000
+
+	for i in $(seq 10 -1 1); do
+		ip nexthop del id $((2000 + i))
+		ip nexthop del id $((1000 + i))
+	done
+}
+
+setup_prepare()
+{
+	h1=${NETIFS[p1]}
+	rp11=${NETIFS[p2]}
+
+	rp12=${NETIFS[p3]}
+	rp22=${NETIFS[p4]}
+
+	rp21=${NETIFS[p5]}
+	h2=${NETIFS[p6]}
+
+	sysctl_save net.ipv4.fib_multipath_hash_seed
+
+	vrf_prepare
+
+	h1_create
+	h2_create
+	router1_create
+	router2_create
+
+	forwarding_enable
+}
+
+cleanup()
+{
+	pre_cleanup
+
+	forwarding_restore
+
+	nexthops_destroy
+	router2_destroy
+	router1_destroy
+	h2_destroy
+	h1_destroy
+
+	vrf_cleanup
+
+	sysctl_restore net.ipv4.fib_multipath_hash_seed
+}
+
+ping_ipv4()
+{
+	ping_test $h1 192.0.2.34
+}
+
+ping_ipv6()
+{
+	ping6_test $h1 2001:db8:3::2
+}
+
+test_mpath_seed_get()
+{
+	RET=0
+
+	local i
+	for ((i = 0; i < 100; i++)); do
+		local seed_w=$((999331 * i))
+		sysctl -qw net.ipv4.fib_multipath_hash_seed=$seed_w
+		local seed_r=$(sysctl -n net.ipv4.fib_multipath_hash_seed)
+		((seed_r == seed_w))
+		check_err $? "mpath seed written as $seed_w, but read as $seed_r"
+	done
+
+	log_test "mpath seed set/get"
+}
+
+nh_stats_snapshot()
+{
+	local group_id=$1; shift
+
+	ip -j -s -s nexthop show id $group_id |
+	    jq -c '[.[].group_stats | sort_by(.id) | .[].packets]'
+}
+
+get_active_nh()
+{
+	local s0=$1; shift
+	local s1=$1; shift
+
+	jq -n --argjson s0 "$s0" --argjson s1 "$s1" -f /dev/stdin <<-"EOF"
+		[range($s0 | length)] |
+		map($s1[.] - $s0[.]) |
+		map(if . > 8 then 1 else 0 end) |
+		index(1)
+	EOF
+}
+
+probe_nh()
+{
+	local group_id=$1; shift
+	local -a mz=("$@")
+
+	local s0=$(nh_stats_snapshot $group_id)
+	"${mz[@]}"
+	local s1=$(nh_stats_snapshot $group_id)
+
+	get_active_nh "$s0" "$s1"
+}
+
+probe_seed()
+{
+	local group_id=$1; shift
+	local seed=$1; shift
+	local -a mz=("$@")
+
+	sysctl -qw net.ipv4.fib_multipath_hash_seed=$seed
+	probe_nh "$group_id" "${mz[@]}"
+}
+
+test_mpath_seed()
+{
+	local group_id=$1; shift
+	local what=$1; shift
+	local -a mz=("$@")
+	local ii
+
+	RET=0
+
+	local -a tally=(0 0 0 0 0 0 0 0 0 0)
+	for ((ii = 0; ii < 100; ii++)); do
+		local act=$(probe_seed $group_id $((999331 * ii)) "${mz[@]}")
+		((tally[act]++))
+	done
+
+	local tally_str="${tally[@]}"
+	for ((ii = 0; ii < ${#tally[@]}; ii++)); do
+		((tally[ii] > 0))
+		check_err $? "NH #$ii not hit, tally='$tally_str'"
+	done
+
+	log_test "mpath seed $what"
+	sysctl -qw net.ipv4.fib_multipath_hash_seed=0
+}
+
+test_mpath_seed_ipv4()
+{
+	test_mpath_seed 1000 IPv4 \
+		$MZ $h1 -A 192.0.2.1 -B 192.0.2.34 -q \
+			-p 64 -d 0 -c 10 -t udp
+}
+
+test_mpath_seed_ipv6()
+{
+	test_mpath_seed 2000 IPv6 \
+		$MZ -6 $h1 -A 2001:db8:1::1 -B 2001:db8:3::2 -q \
+			-p 64 -d 0 -c 10 -t udp
+}
+
+check_mpath_seed_stability()
+{
+	local seed=$1; shift
+	local act_0=$1; shift
+	local act_1=$1; shift
+
+	((act_0 == act_1))
+	check_err $? "seed $seed: active NH moved from $act_0 to $act_1 after seed change"
+}
+
+test_mpath_seed_stability()
+{
+	local group_id=$1; shift
+	local what=$1; shift
+	local -a mz=("$@")
+
+	RET=0
+
+	local seed_0=0
+	local seed_1=3221338814
+	local seed_2=3735928559
+
+	# Initial active NH before touching the seed at all.
+	local act_ini=$(probe_nh $group_id "${mz[@]}")
+
+	local act_0_0=$(probe_seed $group_id $seed_0 "${mz[@]}")
+	local act_1_0=$(probe_seed $group_id $seed_1 "${mz[@]}")
+	local act_2_0=$(probe_seed $group_id $seed_2 "${mz[@]}")
+
+	local act_0_1=$(probe_seed $group_id $seed_0 "${mz[@]}")
+	local act_1_1=$(probe_seed $group_id $seed_1 "${mz[@]}")
+	local act_2_1=$(probe_seed $group_id $seed_2 "${mz[@]}")
+
+	check_mpath_seed_stability initial $act_ini $act_0_0
+	check_mpath_seed_stability $seed_0 $act_0_0 $act_0_1
+	check_mpath_seed_stability $seed_1 $act_1_0 $act_1_1
+	check_mpath_seed_stability $seed_2 $act_2_0 $act_2_1
+
+	log_test "mpath seed stability $what"
+	sysctl -qw net.ipv4.fib_multipath_hash_seed=0
+}
+
+test_mpath_seed_stability_ipv4()
+{
+	test_mpath_seed_stability 1000 IPv4 \
+		$MZ $h1 -A 192.0.2.1 -B 192.0.2.34 -q \
+			-p 64 -d 0 -c 10 -t udp
+}
+
+test_mpath_seed_stability_ipv6()
+{
+	test_mpath_seed_stability 2000 IPv6 \
+		$MZ -6 $h1 -A 2001:db8:1::1 -B 2001:db8:3::2 -q \
+			-p 64 -d 0 -c 10 -t udp
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+nexthops_create
+
+tests_run
+
+exit $EXIT_STATUS