Re: [PATCH net-next v2 5/5] selftests: seg6: add tests for PSP with a consumed SRH

[Hangbin Liu]

On Thu, Nov 05, 2026 at 02:57:15AM +0100, Andrea Mayer wrote:
> Extend srv6_end_flavors_test.sh with tests for the SRv6 End behavior
> with the PSP flavor, alone and together with NEXT-C-SID, on packets that
> carry a consumed SRH in front of the SRH to process.
> 
> Each test sends a ping along an existing SRv6 Policy, and a router on
> the path inserts an extra SRH in front of the Policy's SRH. An End
> behavior on another router consumes the extra SRH, and the router
> connected to the host must then remove only the Policy's SRH.
> 
> These tests set seg6_enabled to 1 on the hosts, which must accept the
> extra SRH, and set it back to 0 at the end. With seg6_enabled set to 1,
> a host also accepts the packet when the Policy's SRH is not removed, or
> when the extra SRH is removed in its place. For this reason, the
> receiving host accepts the echo request only when its first SRH is the
> extra SRH, with Segments Left 0 and followed by the ICMPv6 header. Any
> other echo request is dropped, including one without any SRH. The extra
> SRH is recognized by its last segment, which is the SID that triggered
> its insertion.
> 
> The check on the receiving host uses the ip6tables srh match. Without
> it, these tests are skipped. A test fails if the route that inserts the
> extra SRH, or the rules on the receiving host, cannot be added.
> 
> Signed-off-by: Andrea Mayer <andrea.mayer@xxxxxxxxxxx>
> ---
>  tools/testing/selftests/net/config            |   1 +
>  .../selftests/net/srv6_end_flavors_test.sh    | 280 +++++++++++++++++-
>  2 files changed, 279 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/config b/tools/testing/selftests/net/config
> index 7a89e2618d4c..d5d2382b0b01 100644
> --- a/tools/testing/selftests/net/config
> +++ b/tools/testing/selftests/net/config
> @@ -27,6 +27,7 @@ CONFIG_IP6_NF_IPTABLES=m
>  CONFIG_IP6_NF_IPTABLES_LEGACY=m
>  CONFIG_IP6_NF_MANGLE=m
>  CONFIG_IP6_NF_MATCH_RPFILTER=m
> +CONFIG_IP6_NF_MATCH_SRH=m
>  CONFIG_IP6_NF_NAT=m
>  CONFIG_IP6_NF_RAW=m
>  CONFIG_IP6_NF_TARGET_REJECT=m
> diff --git a/tools/testing/selftests/net/srv6_end_flavors_test.sh b/tools/testing/selftests/net/srv6_end_flavors_test.sh
> index 0355149bb7d6..157baa8ecb0b 100755
> --- a/tools/testing/selftests/net/srv6_end_flavors_test.sh
> +++ b/tools/testing/selftests/net/srv6_end_flavors_test.sh

[...]

> +# In a network namespace, accept the echo requests whose first SRH has the given
> +# SID as last segment (Segment List[0]), SL=0 and the ICMPv6 header after it,
> +# and drop any other echo request, including one without any SRH.
> +# args:
> +#  $1 - network namespace in which the rules are added
> +#  $2 - expected last segment of the first SRH
> +add_srh_check_rules()
> +{
> +	local nsname="$1"
> +	local sid="$2"
> +
> +	ip netns exec "${nsname}" ip6tables -A INPUT \
> +		-p ipv6-icmp --icmpv6-type echo-request \
> +		-m srh --srh-lsid "${sid}" --srh-segs-left-eq 0 \
> +		--srh-next-hdr 58 -j ACCEPT &&
> +	ip netns exec "${nsname}" ip6tables -A INPUT \
> +		-p ipv6-icmp --icmpv6-type echo-request -j DROP
> +}
> +
> +# On a host, check that the echo requests carry the extra SRH alone.
> +# args:
> +#  $1 - host on which the rules are added
> +#  $2 - expected last segment of the first SRH
> +setup_hs_srh_check()
> +{
> +	local hs="$1"
> +	local sid="$2"
> +	local hsname
> +
> +	hsname="$(get_hsname "${hs}")"
> +
> +	add_srh_check_rules "${hsname}" "${sid}"
> +}
> +
> +cleanup_hs_srh_check()
> +{
> +	local hs="$1"
> +	local hsname
> +
> +	hsname="$(get_hsname "${hs}")"
> +
> +	ip netns exec "${hsname}" ip6tables -F INPUT
> +}
> +
> +# Test a Policy with a consumed SRH: a router inserts the extra SRH on the
> +# packets towards a SID, and another router consumes it. The destination host
> +# accepts only the echo requests that carry the extra SRH alone.
> +# args:
> +#  $1 - router that inserts the extra SRH
> +#  $2 - SID that triggers the insertion
> +#  $3 - router with the SRv6 End behavior that consumes the extra SRH
> +#  $4 - source host
> +#  $5 - destination host
> +#  $6 - suffix of the address on the loopback of the destination host
> +#       (i.e. cafe::<host>:<suffix>), if any
> +check_and_log_consumed_srh()
> +{
> +	local rt="$1"
> +	local sid="$2"
> +	local end_rt="$3"
> +	local hssrc="$4"
> +	local hsdst="$5"
> +	local suffix="$6"
> +	local msg
> +
> +	if ! ${HAS_SRH_MATCH}; then
> +		msg="IPv6 Hosts connectivity: hs-${hssrc} -> hs-${hsdst}"
> +		if [ -n "${suffix}" ]; then
> +			msg="${msg} (${IPv6_HS_NETWORK}::${hsdst}:${suffix})"
> +		fi
> +		log_test_skipped "${msg}"
> +		return
> +	fi
> +
> +	if ! setup_rt_consumed_srh "${rt}" "${sid}" "${end_rt}"; then
> +		log_test 1 0 "Extra SRH on rt-${rt} for ${sid}"
> +		return
> +	fi
> +
> +	if ! setup_hs_srh_check "${hsdst}" "${sid}"; then
> +		log_test 1 0 "SRH check on hs-${hsdst} for ${sid}"
> +	elif [ -n "${suffix}" ]; then
> +		check_and_log_hs_lo_addr_connectivity "${hssrc}" "${hsdst}" \
> +			"${suffix}"
> +	else
> +		check_and_log_hs_connectivity "${hssrc}" "${hsdst}"
> +	fi
> +
> +	cleanup_hs_srh_check "${hsdst}"
> +	cleanup_rt_consumed_srh "${rt}" "${sid}"
> +}
> +
> +host_srv6_end_flv_consumed_srh_tests()
> +{
> +	local sid
> +
> +	log_section \
> +		"SRv6 connectivity test hosts (h1 <-> h2, PSP with a consumed SRH)"
> +
> +	if ! ${HAS_SRH_MATCH}; then
> +		echo "SKIP: ip6tables srh match not available"
> +	fi
> +
> +	set_hs_seg6_enabled 1
> +
> +	# Policy (i.a): rt-4 inserts the extra SRH consumed by rt-3
> +	sid="${LOCATOR_SERVICE}:2::${END_PSP_FUNC}"
> +	check_and_log_consumed_srh 4 "${sid}" 3 1 2
> +
> +	# Policy (i.b): rt-2 inserts the extra SRH consumed by rt-3
> +	sid="${LOCATOR_SERVICE}:1::${END_PSP_FUNC}"
> +	check_and_log_consumed_srh 2 "${sid}" 3 2 1
> +
> +	# Policy (i.c): rt-4 inserts the extra SRH consumed by rt-3
> +	sid="$(build_csid_container 2 "${END_CSID_PSP_FUNC}")"
> +	check_and_log_consumed_srh 4 "${sid}" 3 1 2 "${END_CSID_PSP_FUNC}"
> +
> +	# Policy (i.d): rt-3 inserts the extra SRH consumed by rt-4
> +	sid="$(build_csid_container 1 "${END_CSID_PSP_FUNC}")"
> +	check_and_log_consumed_srh 3 "${sid}" 4 2 1 "${END_CSID_PSP_FUNC}"
> +
> +	set_hs_seg6_enabled 0
> +}
> +
>  test_iproute2_supp_or_ksft_skip()
>  {
>  	local flavor="$1"
> @@ -1102,6 +1354,28 @@ test_kernel_supp_or_ksft_skip()
>  	ip netns del "${test_netns}"
>  }
>  
> +# Before enabling the tests with a consumed SRH, make sure that the rules they
> +# use can be added.
> +check_srh_match_support()
> +{
> +	local srhm_ns
> +
> +	if [ ! -x "$(command -v ip6tables)" ]; then
> +		return
> +	fi
> +
> +	if ! setup_ns srhm_ns; then
> +		return
> +	fi
> +
> +	if add_srh_check_rules "${srhm_ns}" "${IPv6_TESTS_ADDR}" \
> +		&>/dev/null; then
> +		HAS_SRH_MATCH=true
> +	fi
> +
> +	cleanup_ns "${srhm_ns}"
> +}
> +
>  test_dummy_dev_or_ksft_skip()
>  {
>  	local test_netns
> @@ -1145,6 +1419,7 @@ test_dummy_dev_or_ksft_skip
>  # supports PSP also supports NEXT-C-SID.
>  test_iproute2_supp_or_ksft_skip psp
>  test_kernel_supp_or_ksft_skip psp
> +check_srh_match_support
>  
>  set -e
>  trap cleanup EXIT
> @@ -1156,5 +1431,6 @@ router_tests
>  host2gateway_tests
>  host_srv6_end_flv_psp_tests
>  host_srv6_end_flv_next_csid_psp_tests
> +host_srv6_end_flv_consumed_srh_tests
>  
>  print_log_test_results
> -- 
> 2.43.0
> 

Tested-by: Hangbin Liu <liuhangbin@xxxxxxxxxx>
Reviewed-by: Hangbin Liu <liuhangbin@xxxxxxxxxx>