selftests: net: add arp_ndisc_evict_nocarrier

This tests the sysctl options for ARP/ND:

/net/ipv4/conf/<iface>/arp_evict_nocarrier
/net/ipv4/conf/all/arp_evict_nocarrier
/net/ipv6/conf/<iface>/ndisc_evict_nocarrier
/net/ipv6/conf/all/ndisc_evict_nocarrier
Signed-off-by: James Prestwood <prestwoj@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/arp_ndisc_evict_nocarrier.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Tests sysctl options {arp,ndisc}_evict_nocarrier={0,1}
+#
+# Create a veth pair and set IPs/routes on both. Then ping to establish
+# an entry in the ARP/ND table. Depending on the test set sysctl option to
+# 1 or 0. Set remote veth down which will cause local veth to go into a no
+# carrier state. Depending on the test check the ARP/ND table:
+#
+# {arp,ndisc}_evict_nocarrier=1 should contain no ARP/ND after no carrier
+# {arp,ndisc}_evict_nocarrer=0 should still contain the single ARP/ND entry
+#
+
+readonly PEER_NS="ns-peer-$(mktemp -u XXXXXX)"
+readonly V4_ADDR0=10.0.10.1
+readonly V4_ADDR1=10.0.10.2
+readonly V6_ADDR0=2001:db8:91::1
+readonly V6_ADDR1=2001:db8:91::2
+nsid=100
+
+cleanup_v6()
+{
+    ip netns del me
+    ip netns del peer
+
+    sysctl -w net.ipv4.conf.veth0.ndisc_evict_nocarrier=1 >/dev/null 2>&1
+    sysctl -w net.ipv4.conf.all.ndisc_evict_nocarrier=1 >/dev/null 2>&1
+}
+
+create_ns()
+{
+    local n=${1}
+
+    ip netns del ${n} 2>/dev/null
+
+    ip netns add ${n}
+    ip netns set ${n} $((nsid++))
+    ip -netns ${n} link set lo up
+}
+
+
+setup_v6() {
+    create_ns me
+    create_ns peer
+
+    IP="ip -netns me"
+
+    $IP li add veth1 type veth peer name veth2
+    $IP li set veth1 up
+    $IP -6 addr add $V6_ADDR0/64 dev veth1 nodad
+    $IP li set veth2 netns peer up
+    ip -netns peer -6 addr add $V6_ADDR1/64 dev veth2 nodad
+
+    ip netns exec me sysctl -w $1 >/dev/null 2>&1
+
+    # Establish an ND cache entry
+    ip netns exec me ping -6 -c1 -Iveth1 $V6_ADDR1 >/dev/null 2>&1
+    # Should have the veth1 entry in ND table
+    ip netns exec me ip -6 neigh get $V6_ADDR1 dev veth1 >/dev/null 2>&1
+    if [ $? -ne 0 ]; then
+        cleanup_v6
+        echo "failed"
+        exit
+    fi
+
+    # Set veth2 down, which will put veth1 in NOCARRIER state
+    ip netns exec peer ip link set veth2 down
+}
+
+setup_v4() {
+    ip netns add "${PEER_NS}"
+    ip link add name veth0 type veth peer name veth1
+    ip link set dev veth0 up
+    ip link set dev veth1 netns "${PEER_NS}"
+    ip netns exec "${PEER_NS}" ip link set dev veth1 up
+    ip addr add $V4_ADDR0/24 dev veth0
+    ip netns exec "${PEER_NS}" ip addr add $V4_ADDR1/24 dev veth1
+    ip netns exec ${PEER_NS} ip route add default via $V4_ADDR1 dev veth1
+    ip route add default via $V4_ADDR0 dev veth0
+
+    sysctl -w "$1" >/dev/null 2>&1
+
+    # Establish an ARP cache entry
+    ping -c1 -I veth0 $V4_ADDR1 -q >/dev/null 2>&1
+    # Should have the veth1 entry in ARP table
+    ip neigh get $V4_ADDR1 dev veth0 >/dev/null 2>&1
+    if [ $? -ne 0 ]; then
+        cleanup_v4
+        echo "failed"
+        exit
+    fi
+
+    # Set veth1 down, which will put veth0 in NOCARRIER state
+    ip netns exec "${PEER_NS}" ip link set veth1 down
+}
+
+cleanup_v4() {
+    ip neigh flush dev veth0
+    ip link del veth0
+    local -r ns="$(ip netns list|grep $PEER_NS)"
+    [ -n "$ns" ] && ip netns del $ns 2>/dev/null
+
+    sysctl -w net.ipv4.conf.veth0.arp_evict_nocarrier=1 >/dev/null 2>&1
+    sysctl -w net.ipv4.conf.all.arp_evict_nocarrier=1 >/dev/null 2>&1
+}
+
+# Run test when arp_evict_nocarrier = 1 (default).
+run_arp_evict_nocarrier_enabled() {
+    echo "run arp_evict_nocarrier=1 test"
+    setup_v4 "net.ipv4.conf.veth0.arp_evict_nocarrier=1"
+
+    # ARP table should be empty
+    ip neigh get $V4_ADDR1 dev veth0 >/dev/null 2>&1
+
+    if [ $? -eq 0 ];then
+        echo "failed"
+    else
+        echo "ok"
+    fi
+
+    cleanup_v4
+}
+
+# Run test when arp_evict_nocarrier = 0
+run_arp_evict_nocarrier_disabled() {
+    echo "run arp_evict_nocarrier=0 test"
+    setup_v4 "net.ipv4.conf.veth0.arp_evict_nocarrier=0"
+
+    # ARP table should still contain the entry
+    ip neigh get $V4_ADDR1 dev veth0 >/dev/null 2>&1
+
+    if [ $? -eq 0 ];then
+        echo "ok"
+    else
+        echo "failed"
+    fi
+
+    cleanup_v4
+}
+
+run_arp_evict_nocarrier_disabled_all() {
+    echo "run all.arp_evict_nocarrier=0 test"
+    setup_v4 "net.ipv4.conf.all.arp_evict_nocarrier=0"
+
+    # ARP table should still contain the entry
+    ip neigh get $V4_ADDR1 dev veth0 >/dev/null 2>&1
+
+    if [ $? -eq 0 ];then
+        echo "ok"
+    else
+        echo "failed"
+    fi
+
+    cleanup_v4
+}
+
+run_ndisc_evict_nocarrier_enabled() {
+    echo "run ndisc_evict_nocarrier=1 test"
+
+    setup_v6 "net.ipv6.conf.veth1.ndisc_evict_nocarrier=1"
+
+    ip netns exec me ip -6 neigh get $V6_ADDR1 dev veth1 >/dev/null 2>&1
+
+    if [ $? -eq 0 ];then
+        echo "failed"
+    else
+        echo "ok"
+    fi
+
+    cleanup_v6
+}
+
+run_ndisc_evict_nocarrier_disabled() {
+    echo "run ndisc_evict_nocarrier=0 test"
+
+    setup_v6 "net.ipv6.conf.veth1.ndisc_evict_nocarrier=0"
+
+    ip netns exec me ip -6 neigh get $V6_ADDR1 dev veth1 >/dev/null 2>&1
+
+    if [ $? -eq 0 ];then
+        echo "ok"
+    else
+        echo "failed"
+    fi
+
+    cleanup_v6
+}
+
+run_ndisc_evict_nocarrier_disabled_all() {
+    echo "run all.ndisc_evict_nocarrier=0 test"
+
+    setup_v6 "net.ipv6.conf.all.ndisc_evict_nocarrier=0"
+
+    ip netns exec me ip -6 neigh get $V6_ADDR1 dev veth1 >/dev/null 2>&1
+
+    if [ $? -eq 0 ];then
+        echo "ok"
+    else
+        echo "failed"
+    fi
+
+    cleanup_v6
+}
+
+run_all_tests() {
+    run_arp_evict_nocarrier_enabled
+    run_arp_evict_nocarrier_disabled
+    run_arp_evict_nocarrier_disabled_all
+    run_ndisc_evict_nocarrier_enabled
+    run_ndisc_evict_nocarrier_disabled
+    run_ndisc_evict_nocarrier_disabled_all
+}
+
+if [ "$(id -u)" -ne 0 ];then
+	echo "SKIP: Need root privileges"
+	exit $ksft_skip;
+fi
+
+run_all_tests