diff options
| -rw-r--r-- | net/ipv6/route.c | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/net/Makefile | 1 | ||||
| -rwxr-xr-x | tools/testing/selftests/net/tcp_ecmp_failover.sh | 216 |
3 files changed, 218 insertions, 0 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 19eb6b702227..0dc0316530ca 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -4995,6 +4995,7 @@ static int fib6_ifdown(struct fib6_info *rt, void *p_arg) rt->fib6_flags & (RTF_LOCAL | RTF_ANYCAST)) break; rt->fib6_nh->fib_nh_flags |= RTNH_F_LINKDOWN; + fib6_update_sernum(net, rt); rt6_multipath_rebalance(rt); break; } diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile index a275ed584026..f3da38c54d27 100644 --- a/tools/testing/selftests/net/Makefile +++ b/tools/testing/selftests/net/Makefile @@ -96,6 +96,7 @@ TEST_PROGS := \ srv6_hl2encap_red_l2vpn_test.sh \ srv6_iptunnel_cache.sh \ stress_reuseport_listen.sh \ + tcp_ecmp_failover.sh \ tcp_fastopen_backup_key.sh \ test_bpf.sh \ test_bridge_backup_port.sh \ diff --git a/tools/testing/selftests/net/tcp_ecmp_failover.sh b/tools/testing/selftests/net/tcp_ecmp_failover.sh new file mode 100755 index 000000000000..5768aa8bff6a --- /dev/null +++ b/tools/testing/selftests/net/tcp_ecmp_failover.sh @@ -0,0 +1,216 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Copyright 2026 Google LLC. +# +# This test verifies TCP flow failover between ECMP routes +# upon carrier loss on the active device. +# +# socat -----------------------------> socat +# | +# .-- veth-c1 -|- veth-s1 --. +# dummy0 -| | |-- dummy0 +# '-- veth-c2 -|- veth-s2 --' +# | +# + +REQUIRE_JQ=no +REQUIRE_MZ=no +NUM_NETIFS=0 + +source forwarding/lib.sh + +CLIENT_IP="10.0.59.1" +SERVER_IP="10.0.92.1" +CLIENT_IP6="2001:db8:5a9a::1" +SERVER_IP6="2001:db8:9292::1" + +setup_server() +{ + IP="ip -n $server" + NS_EXEC="ip netns exec $server" + + $IP link add dummy0 type dummy + $IP link set dummy0 up + + $IP -4 addr add $SERVER_IP/32 dev dummy0 + $IP -6 addr add $SERVER_IP6/128 dev dummy0 nodad + + $IP link set veth-s1 up + $IP link set veth-s2 up + + $IP -4 addr add 192.168.1.2/24 dev veth-s1 + $IP -4 addr add 192.168.2.2/24 dev veth-s2 + + $IP -4 route add $CLIENT_IP/32 \ + nexthop via 192.168.1.1 dev veth-s1 weight 1 \ + nexthop via 192.168.2.1 dev veth-s2 weight 1 + + $IP -6 addr add 2001:db8:1::2/64 dev veth-s1 nodad + $IP -6 addr add 2001:db8:2::2/64 dev veth-s2 nodad + + $IP -6 route add $CLIENT_IP6/128 \ + nexthop via 2001:db8:1::1 dev veth-s1 weight 1 \ + nexthop via 2001:db8:2::1 dev veth-s2 weight 1 +} + +setup_client() +{ + IP="ip -n $client" + NS_EXEC="ip netns exec $client" + + $IP link add dummy0 type dummy + $IP link set dummy0 up + + $IP -4 addr add $CLIENT_IP/32 dev dummy0 + $IP -6 addr add $CLIENT_IP6/128 dev dummy0 nodad + + $IP link set veth-c1 up + $IP link set veth-c2 up + + $IP -4 addr add 192.168.1.1/24 dev veth-c1 + $IP -4 addr add 192.168.2.1/24 dev veth-c2 + + $IP -4 route add $SERVER_IP/32 \ + nexthop via 192.168.1.2 dev veth-c1 weight 1 \ + nexthop via 192.168.2.2 dev veth-c2 weight 1 + + $IP -6 addr add 2001:db8:1::1/64 dev veth-c1 nodad + $IP -6 addr add 2001:db8:2::1/64 dev veth-c2 nodad + + $IP -6 route add $SERVER_IP6/128 \ + nexthop via 2001:db8:1::2 dev veth-c1 weight 1 \ + nexthop via 2001:db8:2::2 dev veth-c2 weight 1 + + # By default, tcp_retries1=3 triggers a route refresh + # after 3 retransmits (~5s). Ensure this never occurs + # for test stability. + $NS_EXEC sysctl -qw net.ipv4.tcp_retries1=100 + + # When NETDEV_CHANGE is issued for a dev tied to an ECMP + # route, RTNH_F_LINKDOWN is flagged and the sernum is + # bumped to invalidate the route via sk_dst_check(). + # + # Without ignore_routes_with_linkdown=1, subsequent + # lookups may still select the same RTNH_F_LINKDOWN route. + $NS_EXEC sysctl -qw net.ipv4.conf.veth-c1.ignore_routes_with_linkdown=1 + $NS_EXEC sysctl -qw net.ipv4.conf.veth-c2.ignore_routes_with_linkdown=1 + + $NS_EXEC sysctl -qw net.ipv6.conf.veth-c1.ignore_routes_with_linkdown=1 + $NS_EXEC sysctl -qw net.ipv6.conf.veth-c2.ignore_routes_with_linkdown=1 +} + +setup() +{ + setup_ns client server + + ip -n "$client" link add veth-c1 type veth peer veth-s1 netns "$server" + ip -n "$client" link add veth-c2 type veth peer veth-s2 netns "$server" + + setup_server + setup_client +} + +cleanup() +{ + cleanup_all_ns > /dev/null 2>&1 +} + +tcp_ecmp_failover() +{ + local pf=$1; shift + local server_ip=$1; shift + local client_ip=$1; shift + + RET=0 + + tcpdump_start veth-s1 "$server" + tcpdump_start veth-s2 "$server" + + ip netns exec "$server" \ + socat -u TCP-LISTEN:8080,pf="$pf",bind="$server_ip",reuseaddr /dev/null & + server_pid=$! + + # Wait for server to start listening. + # Sometimes client fails without this sleep. + sleep 1 + + ip netns exec "$client" \ + socat -u /dev/zero TCP:"$server_ip":8080,pf="$pf",bind="$client_ip" & + client_pid=$! + + # To capture enough packets. + sleep 3 + + tcpdump_stop veth-s1 + tcpdump_stop veth-s2 + + pkts_s1=$(tcpdump_show veth-s1 | wc -l) + pkts_s2=$(tcpdump_show veth-s2 | wc -l) + + tcpdump_cleanup veth-s1 + tcpdump_cleanup veth-s2 + + # Detect the device chosen by the client + if [ "$pkts_s1" -gt "$pkts_s2" ]; then + veth_down=veth-s1 + veth_up=veth-s2 + else + veth_down=veth-s2 + veth_up=veth-s1 + fi + + # Taking down $veth_down causes its peer to lose carrier, + # triggering NETDEV_CHANGE. This flags RTNH_F_LINKDOWN + # and bumps the sernum for the route associated with that + # peer, invalidating the cached dst in the TCP socket. + # + # Consequently, sk_dst_check() fails, forcing the subsequent + # lookup to select the remaining healthy route via $veth_up. + ip -n "$server" link set "$veth_down" down + + tcpdump_start "$veth_up" "$server" + + # To capture enough packets. + sleep 3 + + tcpdump_stop "$veth_up" + + kill -9 "$client_pid" > /dev/null 2>&1 + kill -9 "$server_pid" > /dev/null 2>&1 + wait 2> /dev/null + + pkts=$(tcpdump_show $veth_up | wc -l) + + tcpdump_cleanup "$veth_up" + + if [ "$pkts" -lt 1000 ]; then + RET=$ksft_fail + fi +} + +test_ipv4() +{ + setup + tcp_ecmp_failover IPv4 $SERVER_IP $CLIENT_IP + log_test "TCP IPv4 failover" + cleanup +} + +test_ipv6() +{ + setup + tcp_ecmp_failover IPv6 "[$SERVER_IP6]" "[$CLIENT_IP6]" + log_test "TCP IPv6 failover" + cleanup +} + +require_command socat +require_command tcpdump + +trap cleanup EXIT + +test_ipv4 +test_ipv6 + +exit "$EXIT_STATUS" |