Merge branch 'seg6-headend-reduced'

Andrea Mayer says:

====================
seg6: add support for SRv6 Headend Reduced

This patchset adds support for SRv6 Headend behavior with Reduced
Encapsulation. It introduces the H.Encaps.Red and H.L2Encaps.Red versions
of the SRv6 H.Encaps and H.L2Encaps behaviors, according to RFC 8986 [1].

In details, the patchset is made of:
 - patch 1/4: add support for SRv6 H.Encaps.Red behavior;
 - Patch 2/4: add support for SRv6 H.L2Encaps.Red behavior;
 - patch 2/4: add selftest for SRv6 H.Encaps.Red behavior;
 - patch 3/4: add selftest for SRv6 H.L2Encaps.Red behavior.

The corresponding iproute2 patch for supporting SRv6 H.Encaps.Red and
H.L2Encaps.Red behaviors is provided in a separated patchset.

[1] - https://datatracker.ietf.org/doc/html/rfc8986

V4 -> v5:
 - Fix skb checksum for SRH Reduced encapsulation/insertion;

 - Improve selftests by:
      i) adding a random suffix to network namespaces;
     ii) creating net devices directly into network namespaces;
    iii) using trap EXIT command to properly clean up selftest networks.

 Thanks to Paolo Abeni.

v3 -> v4:
 - Add selftests to the Makefile, thanks to Jakub Kicinski.

v2 -> v3:
 - Keep SRH when HMAC TLV is present;

 - Split the support for H.Encaps.Red and H.L2Encaps.Red behaviors in two
   patches (respectively, patch 1/4 and patch 2/4);

 - Add selftests for SRv6 H.Encaps.Red and H.L2Encaps.Red.

v1 -> v2:
 - Fixed sparse warnings;

 - memset now uses sizeof() instead of hardcoded value;

 - Removed EXPORT_SYMBOL_GPL.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/seg6_iptunnel.h

@@ -35,6 +35,8 @@ enum {
 	SEG6_IPTUN_MODE_INLINE,
 	SEG6_IPTUN_MODE_ENCAP,
 	SEG6_IPTUN_MODE_L2ENCAP,
+	SEG6_IPTUN_MODE_ENCAP_RED,
+	SEG6_IPTUN_MODE_L2ENCAP_RED,
 };
 
 #endif

net/ipv6/seg6_iptunnel.c

@@ -36,9 +36,11 @@ static size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
 	case SEG6_IPTUN_MODE_INLINE:
 		break;
 	case SEG6_IPTUN_MODE_ENCAP:
+	case SEG6_IPTUN_MODE_ENCAP_RED:
 		head = sizeof(struct ipv6hdr);
 		break;
 	case SEG6_IPTUN_MODE_L2ENCAP:
+	case SEG6_IPTUN_MODE_L2ENCAP_RED:
 		return 0;
 	}
 
@@ -197,6 +199,124 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
 }
 EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
 
+/* encapsulate an IPv6 packet within an outer IPv6 header with reduced SRH */
+static int seg6_do_srh_encap_red(struct sk_buff *skb,
+				 struct ipv6_sr_hdr *osrh, int proto)
+{
+	__u8 first_seg = osrh->first_segment;
+	struct dst_entry *dst = skb_dst(skb);
+	struct net *net = dev_net(dst->dev);
+	struct ipv6hdr *hdr, *inner_hdr;
+	int hdrlen = ipv6_optlen(osrh);
+	int red_tlv_offset, tlv_offset;
+	struct ipv6_sr_hdr *isrh;
+	bool skip_srh = false;
+	__be32 flowlabel;
+	int tot_len, err;
+	int red_hdrlen;
+	int tlvs_len;
+
+	if (first_seg > 0) {
+		red_hdrlen = hdrlen - sizeof(struct in6_addr);
+	} else {
+		/* NOTE: if tag/flags and/or other TLVs are introduced in the
+		 * seg6_iptunnel infrastructure, they should be considered when
+		 * deciding to skip the SRH.
+		 */
+		skip_srh = !sr_has_hmac(osrh);
+
+		red_hdrlen = skip_srh ? 0 : hdrlen;
+	}
+
+	tot_len = red_hdrlen + sizeof(struct ipv6hdr);
+
+	err = skb_cow_head(skb, tot_len + skb->mac_len);
+	if (unlikely(err))
+		return err;
+
+	inner_hdr = ipv6_hdr(skb);
+	flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
+
+	skb_push(skb, tot_len);
+	skb_reset_network_header(skb);
+	skb_mac_header_rebuild(skb);
+	hdr = ipv6_hdr(skb);
+
+	/* based on seg6_do_srh_encap() */
+	if (skb->protocol == htons(ETH_P_IPV6)) {
+		ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
+			     flowlabel);
+		hdr->hop_limit = inner_hdr->hop_limit;
+	} else {
+		ip6_flow_hdr(hdr, 0, flowlabel);
+		hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
+
+		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
+		IP6CB(skb)->iif = skb->skb_iif;
+	}
+
+	/* no matter if we have to skip the SRH or not, the first segment
+	 * always comes in the pushed IPv6 header.
+	 */
+	hdr->daddr = osrh->segments[first_seg];
+
+	if (skip_srh) {
+		hdr->nexthdr = proto;
+
+		set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
+		goto out;
+	}
+
+	/* we cannot skip the SRH, slow path */
+
+	hdr->nexthdr = NEXTHDR_ROUTING;
+	isrh = (void *)hdr + sizeof(struct ipv6hdr);
+
+	if (unlikely(!first_seg)) {
+		/* this is a very rare case; we have only one SID but
+		 * we cannot skip the SRH since we are carrying some
+		 * other info.
+		 */
+		memcpy(isrh, osrh, hdrlen);
+		goto srcaddr;
+	}
+
+	tlv_offset = sizeof(*osrh) + (first_seg + 1) * sizeof(struct in6_addr);
+	red_tlv_offset = tlv_offset - sizeof(struct in6_addr);
+
+	memcpy(isrh, osrh, red_tlv_offset);
+
+	tlvs_len = hdrlen - tlv_offset;
+	if (unlikely(tlvs_len > 0)) {
+		const void *s = (const void *)osrh + tlv_offset;
+		void *d = (void *)isrh + red_tlv_offset;
+
+		memcpy(d, s, tlvs_len);
+	}
+
+	--isrh->first_segment;
+	isrh->hdrlen -= 2;
+
+srcaddr:
+	isrh->nexthdr = proto;
+	set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
+
+#ifdef CONFIG_IPV6_SEG6_HMAC
+	if (unlikely(!skip_srh && sr_has_hmac(isrh))) {
+		err = seg6_push_hmac(net, &hdr->saddr, isrh);
+		if (unlikely(err))
+			return err;
+	}
+#endif
+
+out:
+	hdr->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
+
+	skb_postpush_rcsum(skb, hdr, tot_len);
+
+	return 0;
+}
+
 /* insert an SRH within an IPv6 packet, just after the IPv6 header */
 int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
 {
@@ -269,6 +389,7 @@ static int seg6_do_srh(struct sk_buff *skb)
 			return err;
 		break;
 	case SEG6_IPTUN_MODE_ENCAP:
+	case SEG6_IPTUN_MODE_ENCAP_RED:
 		err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6);
 		if (err)
 			return err;
@@ -280,7 +401,11 @@ static int seg6_do_srh(struct sk_buff *skb)
 		else
 			return -EINVAL;
 
-		err = seg6_do_srh_encap(skb, tinfo->srh, proto);
+		if (tinfo->mode == SEG6_IPTUN_MODE_ENCAP)
+			err = seg6_do_srh_encap(skb, tinfo->srh, proto);
+		else
+			err = seg6_do_srh_encap_red(skb, tinfo->srh, proto);
+
 		if (err)
 			return err;
 
@@ -289,6 +414,7 @@ static int seg6_do_srh(struct sk_buff *skb)
 		skb->protocol = htons(ETH_P_IPV6);
 		break;
 	case SEG6_IPTUN_MODE_L2ENCAP:
+	case SEG6_IPTUN_MODE_L2ENCAP_RED:
 		if (!skb_mac_header_was_set(skb))
 			return -EINVAL;
 
@@ -298,7 +424,13 @@ static int seg6_do_srh(struct sk_buff *skb)
 		skb_mac_header_rebuild(skb);
 		skb_push(skb, skb->mac_len);
 
-		err = seg6_do_srh_encap(skb, tinfo->srh, IPPROTO_ETHERNET);
+		if (tinfo->mode == SEG6_IPTUN_MODE_L2ENCAP)
+			err = seg6_do_srh_encap(skb, tinfo->srh,
+						IPPROTO_ETHERNET);
+		else
+			err = seg6_do_srh_encap_red(skb, tinfo->srh,
+						    IPPROTO_ETHERNET);
+
 		if (err)
 			return err;
 
@@ -517,6 +649,10 @@ static int seg6_build_state(struct net *net, struct nlattr *nla,
 		break;
 	case SEG6_IPTUN_MODE_L2ENCAP:
 		break;
+	case SEG6_IPTUN_MODE_ENCAP_RED:
+		break;
+	case SEG6_IPTUN_MODE_L2ENCAP_RED:
+		break;
 	default:
 		return -EINVAL;
 	}

tools/testing/selftests/net/Makefile

@@ -35,6 +35,8 @@ TEST_PROGS += cmsg_time.sh cmsg_ipv6.sh
 TEST_PROGS += srv6_end_dt46_l3vpn_test.sh
 TEST_PROGS += srv6_end_dt4_l3vpn_test.sh
 TEST_PROGS += srv6_end_dt6_l3vpn_test.sh
+TEST_PROGS += srv6_hencap_red_l3vpn_test.sh
+TEST_PROGS += srv6_hl2encap_red_l2vpn_test.sh
 TEST_PROGS += vrf_strict_mode_test.sh
 TEST_PROGS += arp_ndisc_evict_nocarrier.sh
 TEST_PROGS += ndisc_unsolicited_na_test.sh

tools/testing/selftests/net/srv6_hencap_red_l3vpn_test.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# author: Andrea Mayer <andrea.mayer@uniroma2.it>
+#
+# This script is designed for testing the SRv6 H.Encaps.Red behavior.
+#
+# Below is depicted the IPv6 network of an operator which offers advanced
+# IPv4/IPv6 VPN services to hosts, enabling them to communicate with each
+# other.
+# In this example, hosts hs-1 and hs-2 are connected through an IPv4/IPv6 VPN
+# service, while hs-3 and hs-4 are connected using an IPv6 only VPN.
+#
+# Routers rt-1,rt-2,rt-3 and rt-4 implement IPv4/IPv6 L3 VPN services
+# leveraging the SRv6 architecture. The key components for such VPNs are:
+#
+#   i) The SRv6 H.Encaps.Red behavior applies SRv6 Policies on traffic received
+#      by connected hosts, initiating the VPN tunnel. Such a behavior is an
+#      optimization of the SRv6 H.Encap aiming to reduce the length of the SID
+#      List carried in the pushed SRH. Specifically, the H.Encaps.Red removes
+#      the first SID contained in the SID List (i.e. SRv6 Policy) by storing it
+#      into the IPv6 Destination Address. When a SRv6 Policy is made of only one
+#      SID, the SRv6 H.Encaps.Red behavior omits the SRH at all and pushes that
+#      SID directly into the IPv6 DA;
+#
+#  ii) The SRv6 End behavior advances the active SID in the SID List carried by
+#      the SRH;
+#
+# iii) The SRv6 End.DT46 behavior is used for removing the SRv6 Policy and,
+#      thus, it terminates the VPN tunnel. Such a behavior is capable of
+#      handling, at the same time, both tunneled IPv4 and IPv6 traffic.
+#
+#
+#               cafe::1                      cafe::2
+#              10.0.0.1                     10.0.0.2
+#             +--------+                   +--------+
+#             |        |                   |        |
+#             |  hs-1  |                   |  hs-2  |
+#             |        |                   |        |
+#             +---+----+                   +--- +---+
+#    cafe::/64    |                             |      cafe::/64
+#  10.0.0.0/24    |                             |    10.0.0.0/24
+#             +---+----+                   +----+---+
+#             |        |  fcf0:0:1:2::/64  |        |
+#             |  rt-1  +-------------------+  rt-2  |
+#             |        |                   |        |
+#             +---+----+                   +----+---+
+#                 |      .               .      |
+#                 |  fcf0:0:1:3::/64   .        |
+#                 |          .       .          |
+#                 |            .   .            |
+# fcf0:0:1:4::/64 |              .              | fcf0:0:2:3::/64
+#                 |            .   .            |
+#                 |          .       .          |
+#                 |  fcf0:0:2:4::/64   .        |
+#                 |      .               .      |
+#             +---+----+                   +----+---+
+#             |        |                   |        |
+#             |  rt-4  +-------------------+  rt-3  |
+#             |        |  fcf0:0:3:4::/64  |        |
+#             +---+----+                   +----+---+
+#    cafe::/64    |                             |      cafe::/64
+#  10.0.0.0/24    |                             |    10.0.0.0/24
+#             +---+----+                   +--- +---+
+#             |        |                   |        |
+#             |  hs-4  |                   |  hs-3  |
+#             |        |                   |        |
+#             +--------+                   +--------+
+#               cafe::4                      cafe::3
+#              10.0.0.4                     10.0.0.3
+#
+#
+# Every fcf0:0:x:y::/64 network interconnects the SRv6 routers rt-x with rt-y
+# in the IPv6 operator network.
+#
+# Local SID table
+# ===============
+#
+# Each SRv6 router is configured with a Local SID table in which SIDs are
+# stored. Considering the given SRv6 router rt-x, at least two SIDs are
+# configured in the Local SID table:
+#
+#   Local SID table for SRv6 router rt-x
+#   +----------------------------------------------------------+
+#   |fcff:x::e is associated with the SRv6 End behavior        |
+#   |fcff:x::d46 is associated with the SRv6 End.DT46 behavior |
+#   +----------------------------------------------------------+
+#
+# The fcff::/16 prefix is reserved by the operator for implementing SRv6 VPN
+# services. Reachability of SIDs is ensured by proper configuration of the IPv6
+# operator's network and SRv6 routers.
+#
+# # SRv6 Policies
+# ===============
+#
+# An SRv6 ingress router applies SRv6 policies to the traffic received from a
+# connected host. SRv6 policy enforcement consists of encapsulating the
+# received traffic into a new IPv6 packet with a given SID List contained in
+# the SRH.
+#
+# IPv4/IPv6 VPN between hs-1 and hs-2
+# -----------------------------------
+#
+# Hosts hs-1 and hs-2 are connected using dedicated IPv4/IPv6 VPNs.
+# Specifically, packets generated from hs-1 and directed towards hs-2 are
+# handled by rt-1 which applies the following SRv6 Policies:
+#
+#   i.a) IPv6 traffic, SID List=fcff:3::e,fcff:4::e,fcff:2::d46
+#  ii.a) IPv4 traffic, SID List=fcff:2::d46
+#
+# Policy (i.a) steers tunneled IPv6 traffic through SRv6 routers
+# rt-3,rt-4,rt-2. Instead, Policy (ii.a) steers tunneled IPv4 traffic through
+# rt-2.
+# The H.Encaps.Red reduces the SID List (i.a) carried in SRH by removing the
+# first SID (fcff:3::e) and pushing it into the IPv6 DA. In case of IPv4
+# traffic, the H.Encaps.Red omits the presence of SRH at all, since the SID
+# List (ii.a) consists of only one SID that can be stored directly in the IPv6
+# DA.
+#
+# On the reverse path (i.e. from hs-2 to hs-1), rt-2 applies the following
+# policies:
+#
+#   i.b) IPv6 traffic, SID List=fcff:1::d46
+#  ii.b) IPv4 traffic, SID List=fcff:4::e,fcff:3::e,fcff:1::d46
+#
+# Policy (i.b) steers tunneled IPv6 traffic through the SRv6 router rt-1.
+# Conversely, Policy (ii.b) steers tunneled IPv4 traffic through SRv6 routers
+# rt-4,rt-3,rt-1.
+# The H.Encaps.Red omits the SRH at all in case of (i.b) by pushing the single
+# SID (fcff::1::d46) inside the IPv6 DA.
+# The H.Encaps.Red reduces the SID List (ii.b) in the SRH by removing the first
+# SID (fcff:4::e) and pushing it into the IPv6 DA.
+#
+# In summary:
+#  hs-1->hs-2 |IPv6 DA=fcff:3::e|SRH SIDs=fcff:4::e,fcff:2::d46|IPv6|...| (i.a)
+#  hs-1->hs-2 |IPv6 DA=fcff:2::d46|IPv4|...|                              (ii.a)
+#
+#  hs-2->hs-1 |IPv6 DA=fcff:1::d46|IPv6|...|                              (i.b)
+#  hs-2->hs-1 |IPv6 DA=fcff:4::e|SRH SIDs=fcff:3::e,fcff:1::d46|IPv4|...| (ii.b)
+#
+#
+# IPv6 VPN between hs-3 and hs-4
+# ------------------------------
+#
+# Hosts hs-3 and hs-4 are connected using a dedicated IPv6 only VPN.
+# Specifically, packets generated from hs-3 and directed towards hs-4 are
+# handled by rt-3 which applies the following SRv6 Policy:
+#
+#  i.c) IPv6 traffic, SID List=fcff:2::e,fcff:4::d46
+#
+# Policy (i.c) steers tunneled IPv6 traffic through SRv6 routers rt-2,rt-4.
+# The H.Encaps.Red reduces the SID List (i.c) carried in SRH by pushing the
+# first SID (fcff:2::e) in the IPv6 DA.
+#
+# On the reverse path (i.e. from hs-4 to hs-3) the router rt-4 applies the
+# following SRv6 Policy:
+#
+#  i.d) IPv6 traffic, SID List=fcff:1::e,fcff:3::d46.
+#
+# Policy (i.d) steers tunneled IPv6 traffic through SRv6 routers rt-1,rt-3.
+# The H.Encaps.Red reduces the SID List (i.d) carried in SRH by pushing the
+# first SID (fcff:1::e) in the IPv6 DA.
+#
+# In summary:
+#  hs-3->hs-4 |IPv6 DA=fcff:2::e|SRH SIDs=fcff:4::d46|IPv6|...| (i.c)
+#  hs-4->hs-3 |IPv6 DA=fcff:1::e|SRH SIDs=fcff:3::d46|IPv6|...| (i.d)
+#
+
+# Kselftest framework requirement - SKIP code is 4.
+readonly ksft_skip=4
+
+readonly RDMSUFF="$(mktemp -u XXXXXXXX)"
+readonly VRF_TID=100
+readonly VRF_DEVNAME="vrf-${VRF_TID}"
+readonly RT2HS_DEVNAME="veth-t${VRF_TID}"
+readonly LOCALSID_TABLE_ID=90
+readonly IPv6_RT_NETWORK=fcf0:0
+readonly IPv6_HS_NETWORK=cafe
+readonly IPv4_HS_NETWORK=10.0.0
+readonly VPN_LOCATOR_SERVICE=fcff
+readonly END_FUNC=000e
+readonly DT46_FUNC=0d46
+
+PING_TIMEOUT_SEC=4
+PAUSE_ON_FAIL=${PAUSE_ON_FAIL:=no}
+
+# IDs of routers and hosts are initialized during the setup of the testing
+# network
+ROUTERS=''
+HOSTS=''
+
+SETUP_ERR=1
+
+ret=${ksft_skip}
+nsuccess=0
+nfail=0
+
+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
+			[ "$a" = "q" ] && exit 1
+		fi
+	fi
+}
+
+print_log_test_results()
+{
+	printf "\nTests passed: %3d\n" "${nsuccess}"
+	printf "Tests failed: %3d\n"   "${nfail}"
+
+	# when a test fails, the value of 'ret' is set to 1 (error code).
+	# Conversely, when all tests are passed successfully, the 'ret' value
+	# is set to 0 (success code).
+	if [ "${ret}" -ne 1 ]; then
+		ret=0
+	fi
+}
+
+log_section()
+{
+	echo
+	echo "################################################################################"
+	echo "TEST SECTION: $*"
+	echo "################################################################################"
+}
+
+test_command_or_ksft_skip()
+{
+	local cmd="$1"
+
+	if [ ! -x "$(command -v "${cmd}")" ]; then
+		echo "SKIP: Could not run test without \"${cmd}\" tool";
+		exit "${ksft_skip}"
+	fi
+}
+
+get_nodename()
+{
+	local name="$1"
+
+	echo "${name}-${RDMSUFF}"
+}
+
+get_rtname()
+{
+	local rtid="$1"
+
+	get_nodename "rt-${rtid}"
+}
+
+get_hsname()
+{
+	local hsid="$1"
+
+	get_nodename "hs-${hsid}"
+}
+
+__create_namespace()
+{
+	local name="$1"
+
+	ip netns add "${name}"
+}
+
+create_router()
+{
+	local rtid="$1"
+	local nsname
+
+	nsname="$(get_rtname "${rtid}")"
+
+	__create_namespace "${nsname}"
+}
+
+create_host()
+{
+	local hsid="$1"
+	local nsname
+
+	nsname="$(get_hsname "${hsid}")"
+
+	__create_namespace "${nsname}"
+}
+
+cleanup()
+{
+	local nsname
+	local i
+
+	# destroy routers
+	for i in ${ROUTERS}; do
+		nsname="$(get_rtname "${i}")"
+
+		ip netns del "${nsname}" &>/dev/null || true
+	done
+
+	# destroy hosts
+	for i in ${HOSTS}; do
+		nsname="$(get_hsname "${i}")"
+
+		ip netns del "${nsname}" &>/dev/null || true
+	done
+
+	# check whether the setup phase was completed successfully or not. In
+	# case of an error during the setup phase of the testing environment,
+	# the selftest is considered as "skipped".
+	if [ "${SETUP_ERR}" -ne 0 ]; then
+		echo "SKIP: Setting up the testing environment failed"
+		exit "${ksft_skip}"
+	fi
+
+	exit "${ret}"
+}
+
+add_link_rt_pairs()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local neigh
+	local nsname
+	local neigh_nsname
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		neigh_nsname="$(get_rtname "${neigh}")"
+
+		ip link add "veth-rt-${rt}-${neigh}" netns "${nsname}" \
+			type veth peer name "veth-rt-${neigh}-${rt}" \
+			netns "${neigh_nsname}"
+	done
+}
+
+get_network_prefix()
+{
+	local rt="$1"
+	local neigh="$2"
+	local p="${rt}"
+	local q="${neigh}"
+
+	if [ "${p}" -gt "${q}" ]; then
+		p="${q}"; q="${rt}"
+	fi
+
+	echo "${IPv6_RT_NETWORK}:${p}:${q}"
+}
+
+# Setup the basic networking for the routers
+setup_rt_networking()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local nsname
+	local net_prefix
+	local devname
+	local neigh
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		devname="veth-rt-${rt}-${neigh}"
+
+		net_prefix="$(get_network_prefix "${rt}" "${neigh}")"
+
+		ip -netns "${nsname}" addr \
+			add "${net_prefix}::${rt}/64" dev "${devname}" nodad
+
+		ip -netns "${nsname}" link set "${devname}" up
+	done
+
+	ip -netns "${nsname}" link set lo up
+
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.all.accept_dad=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.default.accept_dad=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.all.forwarding=1
+
+	ip netns exec "${nsname}" sysctl -wq net.ipv4.conf.all.rp_filter=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv4.conf.default.rp_filter=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv4.ip_forward=1
+}
+
+# Setup local SIDs for an SRv6 router
+setup_rt_local_sids()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local net_prefix
+	local devname
+	local nsname
+	local neigh
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		devname="veth-rt-${rt}-${neigh}"
+
+		net_prefix="$(get_network_prefix "${rt}" "${neigh}")"
+
+		# set underlay network routes for SIDs reachability
+		ip -netns "${nsname}" -6 route \
+			add "${VPN_LOCATOR_SERVICE}:${neigh}::/32" \
+			table "${LOCALSID_TABLE_ID}" \
+			via "${net_prefix}::${neigh}" dev "${devname}"
+	done
+
+	# Local End behavior (note that "dev" is dummy and the VRF is chosen
+	# for the sake of simplicity).
+	ip -netns "${nsname}" -6 route \
+		add "${VPN_LOCATOR_SERVICE}:${rt}::${END_FUNC}" \
+		table "${LOCALSID_TABLE_ID}" \
+		encap seg6local action End dev "${VRF_DEVNAME}"
+
+	# Local End.DT46 behavior
+	ip -netns "${nsname}" -6 route \
+		add "${VPN_LOCATOR_SERVICE}:${rt}::${DT46_FUNC}" \
+		table "${LOCALSID_TABLE_ID}" \
+		encap seg6local action End.DT46 vrftable "${VRF_TID}" \
+		dev "${VRF_DEVNAME}"
+
+	# all SIDs for VPNs start with a common locator. Routes and SRv6
+	# Endpoint behavior instaces are grouped together in the 'localsid'
+	# table.
+	ip -netns "${nsname}" -6 rule \
+		add to "${VPN_LOCATOR_SERVICE}::/16" \
+		lookup "${LOCALSID_TABLE_ID}" prio 999
+
+	# set default routes to unreachable for both ipv4 and ipv6
+	ip -netns "${nsname}" -6 route \
+		add unreachable default metric 4278198272 \
+		vrf "${VRF_DEVNAME}"
+
+	ip -netns "${nsname}" -4 route \
+		add unreachable default metric 4278198272 \
+		vrf "${VRF_DEVNAME}"
+}
+
+# build and install the SRv6 policy into the ingress SRv6 router.
+# args:
+#  $1 - destination host (i.e. cafe::x host)
+#  $2 - SRv6 router configured for enforcing the SRv6 Policy
+#  $3 - SRv6 routers configured for steering traffic (End behaviors)
+#  $4 - SRv6 router configured for removing the SRv6 Policy (router connected
+#       to the destination host)
+#  $5 - encap mode (full or red)
+#  $6 - traffic type (IPv6 or IPv4)
+__setup_rt_policy()
+{
+	local dst="$1"
+	local encap_rt="$2"
+	local end_rts="$3"
+	local dec_rt="$4"
+	local mode="$5"
+	local traffic="$6"
+	local nsname
+	local policy=''
+	local n
+
+	nsname="$(get_rtname "${encap_rt}")"
+
+	for n in ${end_rts}; do
+		policy="${policy}${VPN_LOCATOR_SERVICE}:${n}::${END_FUNC},"
+	done
+
+	policy="${policy}${VPN_LOCATOR_SERVICE}:${dec_rt}::${DT46_FUNC}"
+
+	# add SRv6 policy to incoming traffic sent by connected hosts
+	if [ "${traffic}" -eq 6 ]; then
+		ip -netns "${nsname}" -6 route \
+			add "${IPv6_HS_NETWORK}::${dst}" vrf "${VRF_DEVNAME}" \
+			encap seg6 mode "${mode}" segs "${policy}" \
+			dev "${VRF_DEVNAME}"
+
+		ip -netns "${nsname}" -6 neigh \
+			add proxy "${IPv6_HS_NETWORK}::${dst}" \
+			dev "${RT2HS_DEVNAME}"
+	else
+		# "dev" must be different from the one where the packet is
+		# received, otherwise the proxy arp does not work.
+		ip -netns "${nsname}" -4 route \
+			add "${IPv4_HS_NETWORK}.${dst}" vrf "${VRF_DEVNAME}" \
+			encap seg6 mode "${mode}" segs "${policy}" \
+			dev "${VRF_DEVNAME}"
+	fi
+}
+
+# see __setup_rt_policy
+setup_rt_policy_ipv6()
+{
+	__setup_rt_policy "$1" "$2" "$3" "$4" "$5" 6
+}
+
+#see __setup_rt_policy
+setup_rt_policy_ipv4()
+{
+	__setup_rt_policy "$1" "$2" "$3" "$4" "$5" 4
+}
+
+setup_hs()
+{
+	local hs="$1"
+	local rt="$2"
+	local hsname
+	local rtname
+
+	hsname="$(get_hsname "${hs}")"
+	rtname="$(get_rtname "${rt}")"
+
+	ip netns exec "${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 "${RT2HS_DEVNAME}" netns "${rtname}"
+
+	ip -netns "${hsname}" addr \
+		add "${IPv6_HS_NETWORK}::${hs}/64" dev veth0 nodad
+	ip -netns "${hsname}" addr add "${IPv4_HS_NETWORK}.${hs}/24" dev veth0
+
+	ip -netns "${hsname}" link set veth0 up
+	ip -netns "${hsname}" link set lo up
+
+	# configure the VRF on the router which is directly connected to the
+	# source host.
+	ip -netns "${rtname}" link \
+		add "${VRF_DEVNAME}" type vrf table "${VRF_TID}"
+	ip -netns "${rtname}" link set "${VRF_DEVNAME}" up
+
+	# enslave the veth interface connecting the router with the host to the
+	# VRF in the access router
+	ip -netns "${rtname}" link \
+		set "${RT2HS_DEVNAME}" master "${VRF_DEVNAME}"
+
+	ip -netns "${rtname}" addr \
+		add "${IPv6_HS_NETWORK}::254/64" dev "${RT2HS_DEVNAME}" nodad
+	ip -netns "${rtname}" addr \
+		add "${IPv4_HS_NETWORK}.254/24" dev "${RT2HS_DEVNAME}"
+
+	ip -netns "${rtname}" link set "${RT2HS_DEVNAME}" up
+
+	ip netns exec "${rtname}" \
+		sysctl -wq net.ipv6.conf."${RT2HS_DEVNAME}".proxy_ndp=1
+	ip netns exec "${rtname}" \
+		sysctl -wq net.ipv4.conf."${RT2HS_DEVNAME}".proxy_arp=1
+
+	# disable the rp_filter otherwise the kernel gets confused about how
+	# to route decap ipv4 packets.
+	ip netns exec "${rtname}" \
+		sysctl -wq net.ipv4.conf."${RT2HS_DEVNAME}".rp_filter=0
+
+	ip netns exec "${rtname}" sh -c "echo 1 > /proc/sys/net/vrf/strict_mode"
+}
+
+setup()
+{
+	local i
+
+	# create routers
+	ROUTERS="1 2 3 4"; readonly ROUTERS
+	for i in ${ROUTERS}; do
+		create_router "${i}"
+	done
+
+	# create hosts
+	HOSTS="1 2 3 4"; readonly HOSTS
+	for i in ${HOSTS}; do
+		create_host "${i}"
+	done
+
+	# set up the links for connecting routers
+	add_link_rt_pairs 1 "2 3 4"
+	add_link_rt_pairs 2 "3 4"
+	add_link_rt_pairs 3 "4"
+
+	# set up the basic connectivity of routers and routes required for
+	# reachability of SIDs.
+	setup_rt_networking 1 "2 3 4"
+	setup_rt_networking 2 "1 3 4"
+	setup_rt_networking 3 "1 2 4"
+	setup_rt_networking 4 "1 2 3"
+
+	# set up the hosts connected to routers
+	setup_hs 1 1
+	setup_hs 2 2
+	setup_hs 3 3
+	setup_hs 4 4
+
+	# set up default SRv6 Endpoints (i.e. SRv6 End and SRv6 End.DT46)
+	setup_rt_local_sids 1 "2 3 4"
+	setup_rt_local_sids 2 "1 3 4"
+	setup_rt_local_sids 3 "1 2 4"
+	setup_rt_local_sids 4 "1 2 3"
+
+	# set up SRv6 policies
+
+	# create an IPv6 VPN between hosts hs-1 and hs-2.
+	# the network path between hs-1 and hs-2 traverses several routers
+	# depending on the direction of traffic.
+	#
+	# Direction hs-1 -> hs-2 (H.Encaps.Red)
+	#  - rt-3,rt-4 (SRv6 End behaviors)
+	#  - rt-2 (SRv6 End.DT46 behavior)
+	#
+	# Direction hs-2 -> hs-1 (H.Encaps.Red)
+	#  - rt-1 (SRv6 End.DT46 behavior)
+	setup_rt_policy_ipv6 2 1 "3 4" 2 encap.red
+	setup_rt_policy_ipv6 1 2 "" 1 encap.red
+
+	# create an IPv4 VPN between hosts hs-1 and hs-2
+	# the network path between hs-1 and hs-2 traverses several routers
+	# depending on the direction of traffic.
+	#
+	# Direction hs-1 -> hs-2 (H.Encaps.Red)
+	# - rt-2 (SRv6 End.DT46 behavior)
+	#
+	# Direction hs-2 -> hs-1 (H.Encaps.Red)
+	#  - rt-4,rt-3 (SRv6 End behaviors)
+	#  - rt-1 (SRv6 End.DT46 behavior)
+	setup_rt_policy_ipv4 2 1 "" 2 encap.red
+	setup_rt_policy_ipv4 1 2 "4 3" 1 encap.red
+
+	# create an IPv6 VPN between hosts hs-3 and hs-4
+	# the network path between hs-3 and hs-4 traverses several routers
+	# depending on the direction of traffic.
+	#
+	# Direction hs-3 -> hs-4 (H.Encaps.Red)
+	# - rt-2 (SRv6 End Behavior)
+	# - rt-4 (SRv6 End.DT46 behavior)
+	#
+	# Direction hs-4 -> hs-3 (H.Encaps.Red)
+	#  - rt-1 (SRv6 End behavior)
+	#  - rt-3 (SRv6 End.DT46 behavior)
+	setup_rt_policy_ipv6 4 3 "2" 4 encap.red
+	setup_rt_policy_ipv6 3 4 "1" 3 encap.red
+
+	# testing environment was set up successfully
+	SETUP_ERR=0
+}
+
+check_rt_connectivity()
+{
+	local rtsrc="$1"
+	local rtdst="$2"
+	local prefix
+	local rtsrc_nsname
+
+	rtsrc_nsname="$(get_rtname "${rtsrc}")"
+
+	prefix="$(get_network_prefix "${rtsrc}" "${rtdst}")"
+
+	ip netns exec "${rtsrc_nsname}" ping -c 1 -W "${PING_TIMEOUT_SEC}" \
+		"${prefix}::${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_ipv6_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+	local hssrc_nsname
+
+	hssrc_nsname="$(get_hsname "${hssrc}")"
+
+	ip netns exec "${hssrc_nsname}" ping -c 1 -W "${PING_TIMEOUT_SEC}" \
+		"${IPv6_HS_NETWORK}::${hsdst}" >/dev/null 2>&1
+}
+
+check_hs_ipv4_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+	local hssrc_nsname
+
+	hssrc_nsname="$(get_hsname "${hssrc}")"
+
+	ip netns exec "${hssrc_nsname}" ping -c 1 -W "${PING_TIMEOUT_SEC}" \
+		"${IPv4_HS_NETWORK}.${hsdst}" >/dev/null 2>&1
+}
+
+check_and_log_hs2gw_connectivity()
+{
+	local hssrc="$1"
+
+	check_hs_ipv6_connectivity "${hssrc}" 254
+	log_test $? 0 "IPv6 Hosts connectivity: hs-${hssrc} -> gw"
+
+	check_hs_ipv4_connectivity "${hssrc}" 254
+	log_test $? 0 "IPv4 Hosts connectivity: hs-${hssrc} -> gw"
+}
+
+check_and_log_hs_ipv6_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_hs_ipv6_connectivity "${hssrc}" "${hsdst}"
+	log_test $? 0 "IPv6 Hosts connectivity: hs-${hssrc} -> hs-${hsdst}"
+}
+
+check_and_log_hs_ipv4_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_hs_ipv4_connectivity "${hssrc}" "${hsdst}"
+	log_test $? 0 "IPv4 Hosts connectivity: hs-${hssrc} -> hs-${hsdst}"
+}
+
+check_and_log_hs_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_and_log_hs_ipv4_connectivity "${hssrc}" "${hsdst}"
+	check_and_log_hs_ipv6_connectivity "${hssrc}" "${hsdst}"
+}
+
+check_and_log_hs_ipv6_isolation()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	# in this case, the connectivity test must fail
+	check_hs_ipv6_connectivity "${hssrc}" "${hsdst}"
+	log_test $? 1 "IPv6 Hosts isolation: hs-${hssrc} -X-> hs-${hsdst}"
+}
+
+check_and_log_hs_ipv4_isolation()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	# in this case, the connectivity test must fail
+	check_hs_ipv4_connectivity "${hssrc}" "${hsdst}"
+	log_test $? 1 "IPv4 Hosts isolation: hs-${hssrc} -X-> hs-${hsdst}"
+}
+
+check_and_log_hs_isolation()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_and_log_hs_ipv6_isolation "${hssrc}" "${hsdst}"
+	check_and_log_hs_ipv4_isolation "${hssrc}" "${hsdst}"
+}
+
+router_tests()
+{
+	local i
+	local j
+
+	log_section "IPv6 routers connectivity test"
+
+	for i in ${ROUTERS}; do
+		for j in ${ROUTERS}; do
+			if [ "${i}" -eq "${j}" ]; then
+				continue
+			fi
+
+			check_and_log_rt_connectivity "${i}" "${j}"
+		done
+	done
+}
+
+host2gateway_tests()
+{
+	local hs
+
+	log_section "IPv4/IPv6 connectivity test among hosts and gateways"
+
+	for hs in ${HOSTS}; do
+		check_and_log_hs2gw_connectivity "${hs}"
+	done
+}
+
+host_vpn_tests()
+{
+	log_section "SRv6 VPN connectivity test hosts (h1 <-> h2, IPv4/IPv6)"
+
+	check_and_log_hs_connectivity 1 2
+	check_and_log_hs_connectivity 2 1
+
+	log_section "SRv6 VPN connectivity test hosts (h3 <-> h4, IPv6 only)"
+
+	check_and_log_hs_ipv6_connectivity 3 4
+	check_and_log_hs_ipv6_connectivity 4 3
+}
+
+host_vpn_isolation_tests()
+{
+	local l1="1 2"
+	local l2="3 4"
+	local tmp
+	local i
+	local j
+	local k
+
+	log_section "SRv6 VPN isolation test among hosts"
+
+	for k in 0 1; do
+		for i in ${l1}; do
+			for j in ${l2}; do
+				check_and_log_hs_isolation "${i}" "${j}"
+			done
+		done
+
+		# let us test the reverse path
+		tmp="${l1}"; l1="${l2}"; l2="${tmp}"
+	done
+
+	log_section "SRv6 VPN isolation test among hosts (h2 <-> h4, IPv4 only)"
+
+	check_and_log_hs_ipv4_isolation 2 4
+	check_and_log_hs_ipv4_isolation 4 2
+}
+
+test_iproute2_supp_or_ksft_skip()
+{
+	if ! ip route help 2>&1 | grep -qo "encap.red"; then
+		echo "SKIP: Missing SRv6 encap.red support in iproute2"
+		exit "${ksft_skip}"
+	fi
+}
+
+test_vrf_or_ksft_skip()
+{
+	modprobe vrf &>/dev/null || true
+	if [ ! -e /proc/sys/net/vrf/strict_mode ]; then
+		echo "SKIP: vrf sysctl does not exist"
+		exit "${ksft_skip}"
+	fi
+}
+
+if [ "$(id -u)" -ne 0 ]; then
+	echo "SKIP: Need root privileges"
+	exit "${ksft_skip}"
+fi
+
+# required programs to carry out this selftest
+test_command_or_ksft_skip ip
+test_command_or_ksft_skip ping
+test_command_or_ksft_skip sysctl
+test_command_or_ksft_skip grep
+
+test_iproute2_supp_or_ksft_skip
+test_vrf_or_ksft_skip
+
+set -e
+trap cleanup EXIT
+
+setup
+set +e
+
+router_tests
+host2gateway_tests
+host_vpn_tests
+host_vpn_isolation_tests
+
+print_log_test_results

tools/testing/selftests/net/srv6_hl2encap_red_l2vpn_test.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# author: Andrea Mayer <andrea.mayer@uniroma2.it>
+#
+# This script is designed for testing the SRv6 H.L2Encaps.Red behavior.
+#
+# Below is depicted the IPv6 network of an operator which offers L2 VPN
+# services to hosts, enabling them to communicate with each other.
+# In this example, hosts hs-1 and hs-2 are connected through an L2 VPN service.
+# Currently, the SRv6 subsystem in Linux allows hosts hs-1 and hs-2 to exchange
+# full L2 frames as long as they carry IPv4/IPv6.
+#
+# Routers rt-1,rt-2,rt-3 and rt-4 implement L2 VPN services
+# leveraging the SRv6 architecture. The key components for such VPNs are:
+#
+#   i) The SRv6 H.L2Encaps.Red behavior applies SRv6 Policies on traffic
+#      received by connected hosts, initiating the VPN tunnel. Such a behavior
+#      is an optimization of the SRv6 H.L2Encap aiming to reduce the
+#      length of the SID List carried in the pushed SRH. Specifically, the
+#      H.L2Encaps.Red removes the first SID contained in the SID List (i.e. SRv6
+#      Policy) by storing it into the IPv6 Destination Address. When a SRv6
+#      Policy is made of only one SID, the SRv6 H.L2Encaps.Red behavior omits
+#      the SRH at all and pushes that SID directly into the IPv6 DA;
+#
+#  ii) The SRv6 End behavior advances the active SID in the SID List
+#      carried by the SRH;
+#
+# iii) The SRv6 End.DX2 behavior is used for removing the SRv6 Policy
+#      and, thus, it terminates the VPN tunnel. The decapsulated L2 frame is
+#      sent over the interface connected with the destination host.
+#
+#               cafe::1                      cafe::2
+#              10.0.0.1                     10.0.0.2
+#             +--------+                   +--------+
+#             |        |                   |        |
+#             |  hs-1  |                   |  hs-2  |
+#             |        |                   |        |
+#             +---+----+                   +--- +---+
+#    cafe::/64    |                             |      cafe::/64
+#  10.0.0.0/24    |                             |    10.0.0.0/24
+#             +---+----+                   +----+---+
+#             |        |  fcf0:0:1:2::/64  |        |
+#             |  rt-1  +-------------------+  rt-2  |
+#             |        |                   |        |
+#             +---+----+                   +----+---+
+#                 |      .               .      |
+#                 |  fcf0:0:1:3::/64   .        |
+#                 |          .       .          |
+#                 |            .   .            |
+# fcf0:0:1:4::/64 |              .              | fcf0:0:2:3::/64
+#                 |            .   .            |
+#                 |          .       .          |
+#                 |  fcf0:0:2:4::/64   .        |
+#                 |      .               .      |
+#             +---+----+                   +----+---+
+#             |        |                   |        |
+#             |  rt-4  +-------------------+  rt-3  |
+#             |        |  fcf0:0:3:4::/64  |        |
+#             +---+----+                   +----+---+
+#
+#
+# Every fcf0:0:x:y::/64 network interconnects the SRv6 routers rt-x with rt-y
+# in the IPv6 operator network.
+#
+# Local SID table
+# ===============
+#
+# Each SRv6 router is configured with a Local SID table in which SIDs are
+# stored. Considering the given SRv6 router rt-x, at least two SIDs are
+# configured in the Local SID table:
+#
+#   Local SID table for SRv6 router rt-x
+#   +----------------------------------------------------------+
+#   |fcff:x::e is associated with the SRv6 End behavior        |
+#   |fcff:x::d2 is associated with the SRv6 End.DX2 behavior   |
+#   +----------------------------------------------------------+
+#
+# The fcff::/16 prefix is reserved by the operator for implementing SRv6 VPN
+# services. Reachability of SIDs is ensured by proper configuration of the IPv6
+# operator's network and SRv6 routers.
+#
+# SRv6 Policies
+# =============
+#
+# An SRv6 ingress router applies SRv6 policies to the traffic received from a
+# connected host. SRv6 policy enforcement consists of encapsulating the
+# received traffic into a new IPv6 packet with a given SID List contained in
+# the SRH.
+#
+# L2 VPN between hs-1 and hs-2
+# ----------------------------
+#
+# Hosts hs-1 and hs-2 are connected using a dedicated L2 VPN.
+# Specifically, packets generated from hs-1 and directed towards hs-2 are
+# handled by rt-1 which applies the following SRv6 Policies:
+#
+#   i.a) L2 traffic, SID List=fcff:2::d2
+#
+# Policy (i.a) steers tunneled L2 traffic through SRv6 router rt-2.
+# The H.L2Encaps.Red omits the presence of SRH at all, since the SID List
+# consists of only one SID (fcff:2::d2) that can be stored directly in the IPv6
+# DA.
+#
+# On the reverse path (i.e. from hs-2 to hs-1), rt-2 applies the following
+# policies:
+#
+#   i.b) L2 traffic, SID List=fcff:4::e,fcff:3::e,fcff:1::d2
+#
+# Policy (i.b) steers tunneled L2 traffic through the SRv6 routers
+# rt-4,rt-3,rt2. The H.L2Encaps.Red reduces the SID List in the SRH by removing
+# the first SID (fcff:4::e) and pushing it into the IPv6 DA.
+#
+# In summary:
+#  hs-1->hs-2 |IPv6 DA=fcff:2::d2|eth|...|                              (i.a)
+#  hs-2->hs-1 |IPv6 DA=fcff:4::e|SRH SIDs=fcff:3::e,fcff:1::d2|eth|...| (i.b)
+#
+
+# Kselftest framework requirement - SKIP code is 4.
+readonly ksft_skip=4
+
+readonly RDMSUFF="$(mktemp -u XXXXXXXX)"
+readonly DUMMY_DEVNAME="dum0"
+readonly RT2HS_DEVNAME="veth-hs"
+readonly HS_VETH_NAME="veth0"
+readonly LOCALSID_TABLE_ID=90
+readonly IPv6_RT_NETWORK=fcf0:0
+readonly IPv6_HS_NETWORK=cafe
+readonly IPv4_HS_NETWORK=10.0.0
+readonly VPN_LOCATOR_SERVICE=fcff
+readonly MAC_PREFIX=00:00:00:c0:01
+readonly END_FUNC=000e
+readonly DX2_FUNC=00d2
+
+PING_TIMEOUT_SEC=4
+PAUSE_ON_FAIL=${PAUSE_ON_FAIL:=no}
+
+# IDs of routers and hosts are initialized during the setup of the testing
+# network
+ROUTERS=''
+HOSTS=''
+
+SETUP_ERR=1
+
+ret=${ksft_skip}
+nsuccess=0
+nfail=0
+
+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
+			[ "$a" = "q" ] && exit 1
+		fi
+	fi
+}
+
+print_log_test_results()
+{
+	printf "\nTests passed: %3d\n" "${nsuccess}"
+	printf "Tests failed: %3d\n"   "${nfail}"
+
+	# when a test fails, the value of 'ret' is set to 1 (error code).
+	# Conversely, when all tests are passed successfully, the 'ret' value
+	# is set to 0 (success code).
+	if [ "${ret}" -ne 1 ]; then
+		ret=0
+	fi
+}
+
+log_section()
+{
+	echo
+	echo "################################################################################"
+	echo "TEST SECTION: $*"
+	echo "################################################################################"
+}
+
+test_command_or_ksft_skip()
+{
+	local cmd="$1"
+
+	if [ ! -x "$(command -v "${cmd}")" ]; then
+		echo "SKIP: Could not run test without \"${cmd}\" tool";
+		exit "${ksft_skip}"
+	fi
+}
+
+get_nodename()
+{
+	local name="$1"
+
+	echo "${name}-${RDMSUFF}"
+}
+
+get_rtname()
+{
+	local rtid="$1"
+
+	get_nodename "rt-${rtid}"
+}
+
+get_hsname()
+{
+	local hsid="$1"
+
+	get_nodename "hs-${hsid}"
+}
+
+__create_namespace()
+{
+	local name="$1"
+
+	ip netns add "${name}"
+}
+
+create_router()
+{
+	local rtid="$1"
+	local nsname
+
+	nsname="$(get_rtname "${rtid}")"
+
+	__create_namespace "${nsname}"
+}
+
+create_host()
+{
+	local hsid="$1"
+	local nsname
+
+	nsname="$(get_hsname "${hsid}")"
+
+	__create_namespace "${nsname}"
+}
+
+cleanup()
+{
+	local nsname
+	local i
+
+	# destroy routers
+	for i in ${ROUTERS}; do
+		nsname="$(get_rtname "${i}")"
+
+		ip netns del "${nsname}" &>/dev/null || true
+	done
+
+	# destroy hosts
+	for i in ${HOSTS}; do
+		nsname="$(get_hsname "${i}")"
+
+		ip netns del "${nsname}" &>/dev/null || true
+	done
+
+	# check whether the setup phase was completed successfully or not. In
+	# case of an error during the setup phase of the testing environment,
+	# the selftest is considered as "skipped".
+	if [ "${SETUP_ERR}" -ne 0 ]; then
+		echo "SKIP: Setting up the testing environment failed"
+		exit "${ksft_skip}"
+	fi
+
+	exit "${ret}"
+}
+
+add_link_rt_pairs()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local neigh
+	local nsname
+	local neigh_nsname
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		neigh_nsname="$(get_rtname "${neigh}")"
+
+		ip link add "veth-rt-${rt}-${neigh}" netns "${nsname}" \
+			type veth peer name "veth-rt-${neigh}-${rt}" \
+			netns "${neigh_nsname}"
+	done
+}
+
+get_network_prefix()
+{
+	local rt="$1"
+	local neigh="$2"
+	local p="${rt}"
+	local q="${neigh}"
+
+	if [ "${p}" -gt "${q}" ]; then
+		p="${q}"; q="${rt}"
+	fi
+
+	echo "${IPv6_RT_NETWORK}:${p}:${q}"
+}
+
+# Setup the basic networking for the routers
+setup_rt_networking()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local nsname
+	local net_prefix
+	local devname
+	local neigh
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		devname="veth-rt-${rt}-${neigh}"
+
+		net_prefix="$(get_network_prefix "${rt}" "${neigh}")"
+
+		ip -netns "${nsname}" addr \
+			add "${net_prefix}::${rt}/64" dev "${devname}" nodad
+
+		ip -netns "${nsname}" link set "${devname}" up
+	done
+
+	ip -netns "${nsname}" link add "${DUMMY_DEVNAME}" type dummy
+
+	ip -netns "${nsname}" link set "${DUMMY_DEVNAME}" up
+	ip -netns "${nsname}" link set lo up
+
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.all.accept_dad=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.default.accept_dad=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv6.conf.all.forwarding=1
+
+	ip netns exec "${nsname}" sysctl -wq net.ipv4.conf.all.rp_filter=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv4.conf.default.rp_filter=0
+	ip netns exec "${nsname}" sysctl -wq net.ipv4.ip_forward=1
+}
+
+# Setup local SIDs for an SRv6 router
+setup_rt_local_sids()
+{
+	local rt="$1"
+	local rt_neighs="$2"
+	local net_prefix
+	local devname
+	local nsname
+	local neigh
+
+	nsname="$(get_rtname "${rt}")"
+
+	for neigh in ${rt_neighs}; do
+		devname="veth-rt-${rt}-${neigh}"
+
+		net_prefix="$(get_network_prefix "${rt}" "${neigh}")"
+
+		# set underlay network routes for SIDs reachability
+		ip -netns "${nsname}" -6 route \
+			add "${VPN_LOCATOR_SERVICE}:${neigh}::/32" \
+			table "${LOCALSID_TABLE_ID}" \
+			via "${net_prefix}::${neigh}" dev "${devname}"
+	done
+
+	# Local End behavior (note that dev "${DUMMY_DEVNAME}" is a dummy
+	# interface)
+	ip -netns "${nsname}" -6 route \
+		add "${VPN_LOCATOR_SERVICE}:${rt}::${END_FUNC}" \
+		table "${LOCALSID_TABLE_ID}" \
+		encap seg6local action End dev "${DUMMY_DEVNAME}"
+
+	# all SIDs for VPNs start with a common locator. Routes and SRv6
+	# Endpoint behaviors instaces are grouped together in the 'localsid'
+	# table.
+	ip -netns "${nsname}" -6 rule add \
+		to "${VPN_LOCATOR_SERVICE}::/16" \
+		lookup "${LOCALSID_TABLE_ID}" prio 999
+}
+
+# build and install the SRv6 policy into the ingress SRv6 router.
+# args:
+#  $1 - destination host (i.e. cafe::x host)
+#  $2 - SRv6 router configured for enforcing the SRv6 Policy
+#  $3 - SRv6 routers configured for steering traffic (End behaviors)
+#  $4 - SRv6 router configured for removing the SRv6 Policy (router connected
+#       to the destination host)
+#  $5 - encap mode (full or red)
+#  $6 - traffic type (IPv6 or IPv4)
+__setup_rt_policy()
+{
+	local dst="$1"
+	local encap_rt="$2"
+	local end_rts="$3"
+	local dec_rt="$4"
+	local mode="$5"
+	local traffic="$6"
+	local nsname
+	local policy=''
+	local n
+
+	nsname="$(get_rtname "${encap_rt}")"
+
+	for n in ${end_rts}; do
+		policy="${policy}${VPN_LOCATOR_SERVICE}:${n}::${END_FUNC},"
+	done
+
+	policy="${policy}${VPN_LOCATOR_SERVICE}:${dec_rt}::${DX2_FUNC}"
+
+	# add SRv6 policy to incoming traffic sent by connected hosts
+	if [ "${traffic}" -eq 6 ]; then
+		ip -netns "${nsname}" -6 route \
+			add "${IPv6_HS_NETWORK}::${dst}" \
+			encap seg6 mode "${mode}" segs "${policy}" \
+			dev dum0
+	else
+		ip -netns "${nsname}" -4 route \
+			add "${IPv4_HS_NETWORK}.${dst}" \
+			encap seg6 mode "${mode}" segs "${policy}" \
+			dev dum0
+	fi
+}
+
+# see __setup_rt_policy
+setup_rt_policy_ipv6()
+{
+	__setup_rt_policy "$1" "$2" "$3" "$4" "$5" 6
+}
+
+#see __setup_rt_policy
+setup_rt_policy_ipv4()
+{
+	__setup_rt_policy "$1" "$2" "$3" "$4" "$5" 4
+}
+
+setup_decap()
+{
+	local rt="$1"
+	local nsname
+
+	nsname="$(get_rtname "${rt}")"
+
+	# Local End.DX2 behavior
+	ip -netns "${nsname}" -6 route \
+		add "${VPN_LOCATOR_SERVICE}:${rt}::${DX2_FUNC}" \
+		table "${LOCALSID_TABLE_ID}" \
+		encap seg6local action End.DX2 oif "${RT2HS_DEVNAME}" \
+		dev "${RT2HS_DEVNAME}"
+}
+
+setup_hs()
+{
+	local hs="$1"
+	local rt="$2"
+	local hsname
+	local rtname
+
+	hsname="$(get_hsname "${hs}")"
+	rtname="$(get_rtname "${rt}")"
+
+	ip netns exec "${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 "${HS_VETH_NAME}" type veth \
+		peer name "${RT2HS_DEVNAME}" netns "${rtname}"
+
+	ip -netns "${hsname}" addr add "${IPv6_HS_NETWORK}::${hs}/64" \
+		dev "${HS_VETH_NAME}" nodad
+	ip -netns "${hsname}" addr add "${IPv4_HS_NETWORK}.${hs}/24" \
+		dev "${HS_VETH_NAME}"
+
+	ip -netns "${hsname}" link set "${HS_VETH_NAME}" up
+	ip -netns "${hsname}" link set lo up
+
+	ip -netns "${rtname}" addr add "${IPv6_HS_NETWORK}::254/64" \
+		dev "${RT2HS_DEVNAME}" nodad
+	ip -netns "${rtname}" addr \
+		add "${IPv4_HS_NETWORK}.254/24" dev "${RT2HS_DEVNAME}"
+
+	ip -netns "${rtname}" link set "${RT2HS_DEVNAME}" up
+
+	# disable the rp_filter otherwise the kernel gets confused about how
+	# to route decap ipv4 packets.
+	ip netns exec "${rtname}" \
+		sysctl -wq net.ipv4.conf."${RT2HS_DEVNAME}".rp_filter=0
+}
+
+# set an auto-generated mac address
+# args:
+#  $1 - name of the node (e.g.: hs-1, rt-3, etc)
+#  $2 - id of the node (e.g.: 1 for hs-1, 3 for rt-3, etc)
+#  $3 - host part of the IPv6 network address
+#  $4 - name of the network interface to which the generated mac address must
+#       be set.
+set_mac_address()
+{
+	local nodename="$1"
+	local nodeid="$2"
+	local host="$3"
+	local ifname="$4"
+	local nsname
+
+	nsname=$(get_nodename "${nodename}")
+
+	ip -netns "${nsname}" link set dev "${ifname}" down
+
+	ip -netns "${nsname}" link set address "${MAC_PREFIX}:${nodeid}" \
+		dev "${ifname}"
+
+	# the IPv6 address must be set once again after the MAC address has
+	# been changed.
+	ip -netns "${nsname}" addr add "${IPv6_HS_NETWORK}::${host}/64" \
+		dev "${ifname}" nodad
+
+	ip -netns "${nsname}" link set dev "${ifname}" up
+}
+
+set_host_l2peer()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+	local ipprefix="$3"
+	local proto="$4"
+	local hssrc_name
+	local ipaddr
+
+	hssrc_name="$(get_hsname "${hssrc}")"
+
+	if [ "${proto}" -eq 6 ]; then
+		ipaddr="${ipprefix}::${hsdst}"
+	else
+		ipaddr="${ipprefix}.${hsdst}"
+	fi
+
+	ip -netns "${hssrc_name}" route add "${ipaddr}" dev "${HS_VETH_NAME}"
+
+	ip -netns "${hssrc_name}" neigh \
+		add "${ipaddr}" lladdr "${MAC_PREFIX}:${hsdst}" \
+		dev "${HS_VETH_NAME}"
+}
+
+# setup an SRv6 L2 VPN between host hs-x and hs-y (currently, the SRv6
+# subsystem only supports L2 frames whose layer-3 is IPv4/IPv6).
+# args:
+#  $1 - source host
+#  $2 - SRv6 routers configured for steering tunneled traffic
+#  $3 - destination host
+setup_l2vpn()
+{
+	local hssrc="$1"
+	local end_rts="$2"
+	local hsdst="$3"
+	local rtsrc="${hssrc}"
+	local rtdst="${hsdst}"
+
+	# set fixed mac for source node and the neigh MAC address
+	set_mac_address "hs-${hssrc}" "${hssrc}" "${hssrc}" "${HS_VETH_NAME}"
+	set_host_l2peer "${hssrc}" "${hsdst}" "${IPv6_HS_NETWORK}" 6
+	set_host_l2peer "${hssrc}" "${hsdst}" "${IPv4_HS_NETWORK}" 4
+
+	# we have to set the mac address of the veth-host (on ingress router)
+	# to the mac address of the remote peer (L2 VPN destination host).
+	# Otherwise, traffic coming from the source host is dropped at the
+	# ingress router.
+	set_mac_address "rt-${rtsrc}" "${hsdst}" 254 "${RT2HS_DEVNAME}"
+
+	# set the SRv6 Policies at the ingress router
+	setup_rt_policy_ipv6 "${hsdst}" "${rtsrc}" "${end_rts}" "${rtdst}" \
+		l2encap.red 6
+	setup_rt_policy_ipv4 "${hsdst}" "${rtsrc}" "${end_rts}" "${rtdst}" \
+		l2encap.red 4
+
+	# set the decap behavior
+	setup_decap "${rtsrc}"
+}
+
+setup()
+{
+	local i
+
+	# create routers
+	ROUTERS="1 2 3 4"; readonly ROUTERS
+	for i in ${ROUTERS}; do
+		create_router "${i}"
+	done
+
+	# create hosts
+	HOSTS="1 2"; readonly HOSTS
+	for i in ${HOSTS}; do
+		create_host "${i}"
+	done
+
+	# set up the links for connecting routers
+	add_link_rt_pairs 1 "2 3 4"
+	add_link_rt_pairs 2 "3 4"
+	add_link_rt_pairs 3 "4"
+
+	# set up the basic connectivity of routers and routes required for
+	# reachability of SIDs.
+	setup_rt_networking 1 "2 3 4"
+	setup_rt_networking 2 "1 3 4"
+	setup_rt_networking 3 "1 2 4"
+	setup_rt_networking 4 "1 2 3"
+
+	# set up the hosts connected to routers
+	setup_hs 1 1
+	setup_hs 2 2
+
+	# set up default SRv6 Endpoints (i.e. SRv6 End and SRv6 End.DX2)
+	setup_rt_local_sids 1 "2 3 4"
+	setup_rt_local_sids 2 "1 3 4"
+	setup_rt_local_sids 3 "1 2 4"
+	setup_rt_local_sids 4 "1 2 3"
+
+	# create a L2 VPN between hs-1 and hs-2.
+	# NB: currently, H.L2Encap* enables tunneling of L2 frames whose
+	# layer-3 is IPv4/IPv6.
+	#
+	# the network path between hs-1 and hs-2 traverses several routers
+	# depending on the direction of traffic.
+	#
+	# Direction hs-1 -> hs-2 (H.L2Encaps.Red)
+	# - rt-2 (SRv6 End.DX2 behavior)
+	#
+	# Direction hs-2 -> hs-1 (H.L2Encaps.Red)
+	#  - rt-4,rt-3 (SRv6 End behaviors)
+	#  - rt-1 (SRv6 End.DX2 behavior)
+	setup_l2vpn 1 "" 2
+	setup_l2vpn 2 "4 3" 1
+
+	# testing environment was set up successfully
+	SETUP_ERR=0
+}
+
+check_rt_connectivity()
+{
+	local rtsrc="$1"
+	local rtdst="$2"
+	local prefix
+	local rtsrc_nsname
+
+	rtsrc_nsname="$(get_rtname "${rtsrc}")"
+
+	prefix="$(get_network_prefix "${rtsrc}" "${rtdst}")"
+
+	ip netns exec "${rtsrc_nsname}" ping -c 1 -W "${PING_TIMEOUT_SEC}" \
+		"${prefix}::${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_ipv6_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+	local hssrc_nsname
+
+	hssrc_nsname="$(get_hsname "${hssrc}")"
+
+	ip netns exec "${hssrc_nsname}" ping -c 1 -W "${PING_TIMEOUT_SEC}" \
+		"${IPv6_HS_NETWORK}::${hsdst}" >/dev/null 2>&1
+}
+
+check_hs_ipv4_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+	local hssrc_nsname
+
+	hssrc_nsname="$(get_hsname "${hssrc}")"
+
+	ip netns exec "${hssrc_nsname}" ping -c 1 -W "${PING_TIMEOUT_SEC}" \
+		"${IPv4_HS_NETWORK}.${hsdst}" >/dev/null 2>&1
+}
+
+check_and_log_hs2gw_connectivity()
+{
+	local hssrc="$1"
+
+	check_hs_ipv6_connectivity "${hssrc}" 254
+	log_test $? 0 "IPv6 Hosts connectivity: hs-${hssrc} -> gw"
+
+	check_hs_ipv4_connectivity "${hssrc}" 254
+	log_test $? 0 "IPv4 Hosts connectivity: hs-${hssrc} -> gw"
+}
+
+check_and_log_hs_ipv6_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_hs_ipv6_connectivity "${hssrc}" "${hsdst}"
+	log_test $? 0 "IPv6 Hosts connectivity: hs-${hssrc} -> hs-${hsdst}"
+}
+
+check_and_log_hs_ipv4_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_hs_ipv4_connectivity "${hssrc}" "${hsdst}"
+	log_test $? 0 "IPv4 Hosts connectivity: hs-${hssrc} -> hs-${hsdst}"
+}
+
+check_and_log_hs_connectivity()
+{
+	local hssrc="$1"
+	local hsdst="$2"
+
+	check_and_log_hs_ipv4_connectivity "${hssrc}" "${hsdst}"
+	check_and_log_hs_ipv6_connectivity "${hssrc}" "${hsdst}"
+}
+
+router_tests()
+{
+	local i
+	local j
+
+	log_section "IPv6 routers connectivity test"
+
+	for i in ${ROUTERS}; do
+		for j in ${ROUTERS}; do
+			if [ "${i}" -eq "${j}" ]; then
+				continue
+			fi
+
+			check_and_log_rt_connectivity "${i}" "${j}"
+		done
+	done
+}
+
+host2gateway_tests()
+{
+	local hs
+
+	log_section "IPv4/IPv6 connectivity test among hosts and gateways"
+
+	for hs in ${HOSTS}; do
+		check_and_log_hs2gw_connectivity "${hs}"
+	done
+}
+
+host_vpn_tests()
+{
+	log_section "SRv6 L2 VPN connectivity test hosts (h1 <-> h2)"
+
+	check_and_log_hs_connectivity 1 2
+	check_and_log_hs_connectivity 2 1
+}
+
+test_dummy_dev_or_ksft_skip()
+{
+	local test_netns
+
+	test_netns="dummy-$(mktemp -u XXXXXXXX)"
+
+	if ! ip netns add "${test_netns}"; then
+		echo "SKIP: Cannot set up netns for testing dummy dev support"
+		exit "${ksft_skip}"
+	fi
+
+	modprobe dummy &>/dev/null || true
+	if ! ip -netns "${test_netns}" link \
+		add "${DUMMY_DEVNAME}" type dummy; then
+		echo "SKIP: dummy dev not supported"
+
+		ip netns del "${test_netns}"
+		exit "${ksft_skip}"
+	fi
+
+	ip netns del "${test_netns}"
+}
+
+test_iproute2_supp_or_ksft_skip()
+{
+	if ! ip route help 2>&1 | grep -qo "l2encap.red"; then
+		echo "SKIP: Missing SRv6 l2encap.red support in iproute2"
+		exit "${ksft_skip}"
+	fi
+}
+
+if [ "$(id -u)" -ne 0 ]; then
+	echo "SKIP: Need root privileges"
+	exit "${ksft_skip}"
+fi
+
+# required programs to carry out this selftest
+test_command_or_ksft_skip ip
+test_command_or_ksft_skip ping
+test_command_or_ksft_skip sysctl
+test_command_or_ksft_skip grep
+
+test_iproute2_supp_or_ksft_skip
+test_dummy_dev_or_ksft_skip
+
+set -e
+trap cleanup EXIT
+
+setup
+set +e
+
+router_tests
+host2gateway_tests
+host_vpn_tests
+
+print_log_test_results