selftests: add selftest for the SRv6 End.DT6 (VRF) behavior

this selftest is designed for evaluating the new SRv6 End.DT6 (VRF) behavior
used, in this example, for implementing IPv6 L3 VPN use cases.
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: Paolo Lungaroni <paolo.lungaroni@cnit.it>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# author: Andrea Mayer <andrea.mayer@uniroma2.it>
+# author: Paolo Lungaroni <paolo.lungaroni@cnit.it>
+
+# This test is designed for evaluating the new SRv6 End.DT6 behavior used for
+# implementing IPv6 L3 VPN use cases.
+#
+# Hereafter a network diagram is shown, where two different tenants (named 100
+# and 200) offer IPv6 L3 VPN services allowing hosts to communicate with each
+# other across an IPv6 network.
+#
+# Only hosts belonging to the same tenant (and to the same VPN) can communicate
+# with each other. Instead, the communication among hosts of different tenants
+# is forbidden.
+# In other words, hosts hs-t100-1 and hs-t100-2 are connected through the IPv6
+# L3 VPN of tenant 100 while hs-t200-3 and hs-t200-4 are connected using the
+# IPv6 L3 VPN of tenant 200. Cross connection between tenant 100 and tenant 200
+# is forbidden and thus, for example, hs-t100-1 cannot reach hs-t200-3 and vice
+# versa.
+#
+# Routers rt-1 and rt-2 implement IPv6 L3 VPN services leveraging the SRv6
+# architecture. The key components for such VPNs are: a) SRv6 Encap behavior,
+# b) SRv6 End.DT6 behavior and c) VRF.
+#
+# To explain how an IPv6 L3 VPN based on SRv6 works, let us briefly consider an
+# example where, within the same domain of tenant 100, the host hs-t100-1 pings
+# the host hs-t100-2.
+#
+# First of all, L2 reachability of the host hs-t100-2 is taken into account by
+# the router rt-1 which acts as a ndp proxy.
+#
+# When the host hs-t100-1 sends an IPv6 packet destined to hs-t100-2, the
+# router rt-1 receives the packet on the internal veth-t100 interface. Such
+# interface is enslaved to the VRF vrf-100 whose associated table contains the
+# SRv6 Encap route for encapsulating any IPv6 packet in a IPv6 plus the Segment
+# Routing Header (SRH) packet. This packet is sent through the (IPv6) core
+# network up to the router rt-2 that receives it on veth0 interface.
+#
+# The rt-2 router uses the 'localsid' routing table to process incoming
+# IPv6+SRH packets which belong to the VPN of the tenant 100. For each of these
+# packets, the SRv6 End.DT6 behavior removes the outer IPv6+SRH headers and
+# performs the lookup on the vrf-100 table using the destination address of
+# the decapsulated IPv6 packet. Afterwards, the packet is sent to the host
+# hs-t100-2 through the veth-t100 interface.
+#
+# The ping response follows the same processing but this time the role of rt-1
+# and rt-2 are swapped.
+#
+# Of course, the IPv6 L3 VPN for tenant 200 works exactly as the IPv6 L3 VPN
+# for tenant 100. In this case, only hosts hs-t200-3 and hs-t200-4 are able to
+# connect with each other.
+#
+#
+# +-------------------+                                   +-------------------+
+# |                   |                                   |                   |
+# |  hs-t100-1 netns  |                                   |  hs-t100-2 netns  |
+# |                   |                                   |                   |
+# |  +-------------+  |                                   |  +-------------+  |
+# |  |    veth0    |  |                                   |  |    veth0    |  |
+# |  |  cafe::1/64 |  |                                   |  |  cafe::2/64 |  |
+# |  +-------------+  |                                   |  +-------------+  |
+# |        .          |                                   |         .         |
+# +-------------------+                                   +-------------------+
+#          .                                                        .
+#          .                                                        .
+#          .                                                        .
+# +-----------------------------------+   +-----------------------------------+
+# |        .                          |   |                         .         |
+# | +---------------+                 |   |                 +---------------- |
+# | |   veth-t100   |                 |   |                 |   veth-t100   | |
+# | |  cafe::254/64 |    +----------+ |   | +----------+    |  cafe::254/64 | |
+# | +-------+-------+    | localsid | |   | | localsid |    +-------+-------- |
+# |         |            |   table  | |   | |   table  |            |         |
+# |    +----+----+       +----------+ |   | +----------+       +----+----+    |
+# |    | vrf-100 |                    |   |                    | vrf-100 |    |
+# |    +---------+     +------------+ |   | +------------+     +---------+    |
+# |                    |   veth0    | |   | |   veth0    |                    |
+# |                    | fd00::1/64 |.|...|.| fd00::2/64 |                    |
+# |    +---------+     +------------+ |   | +------------+     +---------+    |
+# |    | vrf-200 |                    |   |                    | vrf-200 |    |
+# |    +----+----+                    |   |                    +----+----+    |
+# |         |                         |   |                         |         |
+# | +-------+-------+                 |   |                 +-------+-------- |
+# | |   veth-t200   |                 |   |                 |   veth-t200   | |
+# | |  cafe::254/64 |                 |   |                 |  cafe::254/64 | |
+# | +---------------+      rt-1 netns |   | rt-2 netns      +---------------- |
+# |        .                          |   |                          .        |
+# +-----------------------------------+   +-----------------------------------+
+#          .                                                         .
+#          .                                                         .
+#          .                                                         .
+#          .                                                         .
+# +-------------------+                                   +-------------------+
+# |        .          |                                   |          .        |
+# |  +-------------+  |                                   |  +-------------+  |
+# |  |    veth0    |  |                                   |  |    veth0    |  |
+# |  |  cafe::3/64 |  |                                   |  |  cafe::4/64 |  |
+# |  +-------------+  |                                   |  +-------------+  |
+# |                   |                                   |                   |
+# |  hs-t200-3 netns  |                                   |  hs-t200-4 netns  |
+# |                   |                                   |                   |
+# +-------------------+                                   +-------------------+
+#
+#
+# ~~~~~~~~~~~~~~~~~~~~~~~~~
+# | Network configuration |
+# ~~~~~~~~~~~~~~~~~~~~~~~~~
+#
+# rt-1: localsid table (table 90)
+# +-------------------------------------------------+
+# |SID              |Action                         |
+# +-------------------------------------------------+
+# |fc00:21:100::6006|apply SRv6 End.DT6 vrftable 100|
+# +-------------------------------------------------+
+# |fc00:21:200::6006|apply SRv6 End.DT6 vrftable 200|
+# +-------------------------------------------------+
+#
+# rt-1: VRF tenant 100 (table 100)
+# +---------------------------------------------------+
+# |host       |Action                                 |
+# +---------------------------------------------------+
+# |cafe::2    |apply seg6 encap segs fc00:12:100::6006|
+# +---------------------------------------------------+
+# |cafe::/64  |forward to dev veth_t100               |
+# +---------------------------------------------------+
+#
+# rt-1: VRF tenant 200 (table 200)
+# +---------------------------------------------------+
+# |host       |Action                                 |
+# +---------------------------------------------------+
+# |cafe::4    |apply seg6 encap segs fc00:12:200::6006|
+# +---------------------------------------------------+
+# |cafe::/64  |forward to dev veth_t200               |
+# +---------------------------------------------------+
+#
+#
+# rt-2: localsid table (table 90)
+# +-------------------------------------------------+
+# |SID              |Action                         |
+# +-------------------------------------------------+
+# |fc00:12:100::6006|apply SRv6 End.DT6 vrftable 100|
+# +-------------------------------------------------+
+# |fc00:12:200::6006|apply SRv6 End.DT6 vrftable 200|
+# +-------------------------------------------------+
+#
+# rt-2: VRF tenant 100 (table 100)
+# +---------------------------------------------------+
+# |host       |Action                                 |
+# +---------------------------------------------------+
+# |cafe::1    |apply seg6 encap segs fc00:21:100::6006|
+# +---------------------------------------------------+
+# |cafe::/64  |forward to dev veth_t100               |
+# +---------------------------------------------------+
+#
+# rt-2: VRF tenant 200 (table 200)
+# +---------------------------------------------------+
+# |host       |Action                                 |
+# +---------------------------------------------------+
+# |cafe::3    |apply seg6 encap segs fc00:21:200::6006|
+# +---------------------------------------------------+
+# |cafe::/64  |forward to dev veth_t200               |
+# +---------------------------------------------------+
+#
+
+readonly LOCALSID_TABLE_ID=90
+readonly IPv6_RT_NETWORK=fd00
+readonly IPv6_HS_NETWORK=cafe
+readonly VPN_LOCATOR_SERVICE=fc00
+PING_TIMEOUT_SEC=4
+
+ret=0
+
+PAUSE_ON_FAIL=${PAUSE_ON_FAIL:=no}
+
+log_test()
+{
+	local rc=$1
+	local expected=$2
+	local msg="$3"
+
+	if [ ${rc} -eq ${expected} ]; then
+		nsuccess=$((nsuccess+1))
+		printf "\n    TEST: %-60s  [ OK ]\n" "${msg}"
+	else
+		ret=1
+		nfail=$((nfail+1))
+		printf "\n    TEST: %-60s  [FAIL]\n" "${msg}"
+		if [ "${PAUSE_ON_FAIL}" = "yes" ]; then
+			echo
+			echo "hit enter to continue, 'q' to quit"
+			read a
+			[ "$a" = "q" ] && exit 1
+		fi
+	fi
+}
+
+print_log_test_results()
+{
+	if [ "$TESTS" != "none" ]; then
+		printf "\nTests passed: %3d\n" ${nsuccess}
+		printf "Tests failed: %3d\n"   ${nfail}
+	fi
+}
+
+log_section()
+{
+	echo
+	echo "################################################################################"
+	echo "TEST SECTION: $*"
+	echo "################################################################################"
+}
+
+cleanup()
+{
+	ip link del veth-rt-1 2>/dev/null || true
+	ip link del veth-rt-2 2>/dev/null || true
+
+	# destroy routers rt-* and hosts hs-*
+	for ns in $(ip netns show | grep -E 'rt-*|hs-*'); do
+		ip netns del ${ns} || true
+	done
+}
+
+# Setup the basic networking for the routers
+setup_rt_networking()
+{
+	local rt=$1
+	local nsname=rt-${rt}
+
+	ip netns add ${nsname}
+	ip link set veth-rt-${rt} netns ${nsname}
+	ip -netns ${nsname} link set veth-rt-${rt} name veth0
+
+	ip netns exec ${nsname} sysctl -wq net.ipv6.conf.all.accept_dad=0
+	ip netns exec ${nsname} sysctl -wq net.ipv6.conf.default.accept_dad=0
+
+	ip -netns ${nsname} addr add ${IPv6_RT_NETWORK}::${rt}/64 dev veth0 nodad
+	ip -netns ${nsname} link set veth0 up
+	ip -netns ${nsname} link set lo up
+
+	ip netns exec ${nsname} sysctl -wq net.ipv6.conf.all.forwarding=1
+}
+
+setup_hs()
+{
+	local hs=$1
+	local rt=$2
+	local tid=$3
+	local hsname=hs-t${tid}-${hs}
+	local rtname=rt-${rt}
+	local rtveth=veth-t${tid}
+
+	# set the networking for the host
+	ip netns add ${hsname}
+
+	ip netns exec ${hsname} sysctl -wq net.ipv6.conf.all.accept_dad=0
+	ip netns exec ${hsname} sysctl -wq net.ipv6.conf.default.accept_dad=0
+
+	ip -netns ${hsname} link add veth0 type veth peer name ${rtveth}
+	ip -netns ${hsname} link set ${rtveth} netns ${rtname}
+	ip -netns ${hsname} addr add ${IPv6_HS_NETWORK}::${hs}/64 dev veth0 nodad
+	ip -netns ${hsname} link set veth0 up
+	ip -netns ${hsname} link set lo up
+
+	# configure the VRF for the tenant X on the router which is directly
+	# connected to the source host.
+	ip -netns ${rtname} link add vrf-${tid} type vrf table ${tid}
+	ip -netns ${rtname} link set vrf-${tid} up
+
+	ip netns exec ${rtname} sysctl -wq net.ipv6.conf.all.accept_dad=0
+	ip netns exec ${rtname} sysctl -wq net.ipv6.conf.default.accept_dad=0
+
+	# enslave the veth-tX interface to the vrf-X in the access router
+	ip -netns ${rtname} link set ${rtveth} master vrf-${tid}
+	ip -netns ${rtname} addr add ${IPv6_HS_NETWORK}::254/64 dev ${rtveth} nodad
+	ip -netns ${rtname} link set ${rtveth} up
+
+	ip netns exec ${rtname} sysctl -wq net.ipv6.conf.${rtveth}.proxy_ndp=1
+
+	ip netns exec ${rtname} sh -c "echo 1 > /proc/sys/net/vrf/strict_mode"
+}
+
+setup_vpn_config()
+{
+	local hssrc=$1
+	local rtsrc=$2
+	local hsdst=$3
+	local rtdst=$4
+	local tid=$5
+
+	local hssrc_name=hs-t${tid}-${hssrc}
+	local hsdst_name=hs-t${tid}-${hsdst}
+	local rtsrc_name=rt-${rtsrc}
+	local rtdst_name=rt-${rtdst}
+	local rtveth=veth-t${tid}
+	local vpn_sid=${VPN_LOCATOR_SERVICE}:${hssrc}${hsdst}:${tid}::6006
+
+	ip -netns ${rtsrc_name} -6 neigh add proxy ${IPv6_HS_NETWORK}::${hsdst} dev ${rtveth}
+
+	# set the encap route for encapsulating packets which arrive from the
+	# host hssrc and destined to the access router rtsrc.
+	ip -netns ${rtsrc_name} -6 route add ${IPv6_HS_NETWORK}::${hsdst}/128 vrf vrf-${tid} \
+		encap seg6 mode encap segs ${vpn_sid} dev veth0
+	ip -netns ${rtsrc_name} -6 route add ${vpn_sid}/128 vrf vrf-${tid} \
+		via fd00::${rtdst} dev veth0
+
+	# set the decap route for decapsulating packets which arrive from
+	# the rtdst router and destined to the hsdst host.
+	ip -netns ${rtdst_name} -6 route add ${vpn_sid}/128 table ${LOCALSID_TABLE_ID} \
+		encap seg6local action End.DT6 vrftable ${tid} dev vrf-${tid}
+
+	# all sids for VPNs start with a common locator which is fc00::/16.
+	# Routes for handling the SRv6 End.DT6 behavior instances are grouped
+	# together in the 'localsid' table.
+	#
+	# NOTE: added only once
+	if [ -z "$(ip -netns ${rtdst_name} -6 rule show | \
+	    grep "to ${VPN_LOCATOR_SERVICE}::/16 lookup ${LOCALSID_TABLE_ID}")" ]; then
+		ip -netns ${rtdst_name} -6 rule add \
+			to ${VPN_LOCATOR_SERVICE}::/16 \
+			lookup ${LOCALSID_TABLE_ID} prio 999
+	fi
+}
+
+setup()
+{
+	ip link add veth-rt-1 type veth peer name veth-rt-2
+	# setup the networking for router rt-1 and router rt-2
+	setup_rt_networking 1
+	setup_rt_networking 2
+
+	# setup two hosts for the tenant 100.
+	#  - host hs-1 is directly connected to the router rt-1;
+	#  - host hs-2 is directly connected to the router rt-2.
+	setup_hs 1 1 100  #args: host router tenant
+	setup_hs 2 2 100
+
+	# setup two hosts for the tenant 200
+	#  - host hs-3 is directly connected to the router rt-1;
+	#  - host hs-4 is directly connected to the router rt-2.
+	setup_hs 3 1 200
+	setup_hs 4 2 200
+
+	# setup the IPv6 L3 VPN which connects the host hs-t100-1 and host
+	# hs-t100-2 within the same tenant 100.
+	setup_vpn_config 1 1 2 2 100  #args: src_host src_router dst_host dst_router tenant
+	setup_vpn_config 2 2 1 1 100
+
+	# setup the IPv6 L3 VPN which connects the host hs-t200-3 and host
+	# hs-t200-4 within the same tenant 200.
+	setup_vpn_config 3 1 4 2 200
+	setup_vpn_config 4 2 3 1 200
+}
+
+check_rt_connectivity()
+{
+	local rtsrc=$1
+	local rtdst=$2
+
+	ip netns exec rt-${rtsrc} ping -c 1 -W 1 ${IPv6_RT_NETWORK}::${rtdst} \
+		>/dev/null 2>&1
+}
+
+check_and_log_rt_connectivity()
+{
+	local rtsrc=$1
+	local rtdst=$2
+
+	check_rt_connectivity ${rtsrc} ${rtdst}
+	log_test $? 0 "Routers connectivity: rt-${rtsrc} -> rt-${rtdst}"
+}
+
+check_hs_connectivity()
+{
+	local hssrc=$1
+	local hsdst=$2
+	local tid=$3
+
+	ip netns exec hs-t${tid}-${hssrc} ping -c 1 -W ${PING_TIMEOUT_SEC} \
+		${IPv6_HS_NETWORK}::${hsdst} >/dev/null 2>&1
+}
+
+check_and_log_hs_connectivity()
+{
+	local hssrc=$1
+	local hsdst=$2
+	local tid=$3
+
+	check_hs_connectivity ${hssrc} ${hsdst} ${tid}
+	log_test $? 0 "Hosts connectivity: hs-t${tid}-${hssrc} -> hs-t${tid}-${hsdst} (tenant ${tid})"
+}
+
+check_and_log_hs_isolation()
+{
+	local hssrc=$1
+	local tidsrc=$2
+	local hsdst=$3
+	local tiddst=$4
+
+	check_hs_connectivity ${hssrc} ${hsdst} ${tidsrc}
+	# NOTE: ping should fail
+	log_test $? 1 "Hosts isolation: hs-t${tidsrc}-${hssrc} -X-> hs-t${tiddst}-${hsdst}"
+}
+
+
+check_and_log_hs2gw_connectivity()
+{
+	local hssrc=$1
+	local tid=$2
+
+	check_hs_connectivity ${hssrc} 254 ${tid}
+	log_test $? 0 "Hosts connectivity: hs-t${tid}-${hssrc} -> gw (tenant ${tid})"
+}
+
+router_tests()
+{
+	log_section "IPv6 routers connectivity test"
+
+	check_and_log_rt_connectivity 1 2
+	check_and_log_rt_connectivity 2 1
+}
+
+host2gateway_tests()
+{
+	log_section "IPv6 connectivity test among hosts and gateway"
+
+	check_and_log_hs2gw_connectivity 1 100
+	check_and_log_hs2gw_connectivity 2 100
+
+	check_and_log_hs2gw_connectivity 3 200
+	check_and_log_hs2gw_connectivity 4 200
+}
+
+host_vpn_tests()
+{
+	log_section "SRv6 VPN connectivity test among hosts in the same tenant"
+
+	check_and_log_hs_connectivity 1 2 100
+	check_and_log_hs_connectivity 2 1 100
+
+	check_and_log_hs_connectivity 3 4 200
+	check_and_log_hs_connectivity 4 3 200
+}
+
+host_vpn_isolation_tests()
+{
+	local i
+	local j
+	local k
+	local tmp
+	local l1="1 2"
+	local l2="3 4"
+	local t1=100
+	local t2=200
+
+	log_section "SRv6 VPN isolation test among hosts in different tentants"
+
+	for k in 0 1; do
+		for i in ${l1}; do
+			for j in ${l2}; do
+				check_and_log_hs_isolation ${i} ${t1} ${j} ${t2}
+			done
+		done
+
+		# let us test the reverse path
+		tmp="${l1}"; l1="${l2}"; l2="${tmp}"
+		tmp=${t1}; t1=${t2}; t2=${tmp}
+	done
+}
+
+if [ "$(id -u)" -ne 0 ];then
+	echo "SKIP: Need root privileges"
+	exit 0
+fi
+
+if [ ! -x "$(command -v ip)" ]; then
+	echo "SKIP: Could not run test without ip tool"
+	exit 0
+fi
+
+modprobe vrf &>/dev/null
+if [ ! -e /proc/sys/net/vrf/strict_mode ]; then
+        echo "SKIP: vrf sysctl does not exist"
+        exit 0
+fi
+
+cleanup &>/dev/null
+
+setup
+
+router_tests
+host2gateway_tests
+host_vpn_tests
+host_vpn_isolation_tests
+
+print_log_test_results
+
+cleanup &>/dev/null
+
+exit ${ret}