[PATCH] [net-next, v2] selftest/net: skip srv6_end_dt[4/6]_l3vpn_test.sh if vrftable not available

[Alessio Faina <alessio.faina@canonical.com>]

In case iproute2 is older than version 5.11.0, released ~Feb 23, 2021,
the vrftable support is not available and the tests
contained in the following 4 test files
 - srv6_end_dt4_l3vpn_test.sh
 - srv6_end_dt6_l3vpn_test.sh
are failing in some kernel backports.
This is the result of one those tests in an unsupported environment:

\################################################################################
\TEST SECTION: SRv6 VPN connectivity test among hosts in the same tenant
\################################################################################
\
\    TEST: Hosts connectivity: hs-t100-1 -> hs-t100-2 (tenant 100)       [FAIL]
\
\    TEST: Hosts connectivity: hs-t100-2 -> hs-t100-1 (tenant 100)       [FAIL]
\
\    TEST: Hosts connectivity: hs-t200-3 -> hs-t200-4 (tenant 200)       [FAIL]
\
\    TEST: Hosts connectivity: hs-t200-4 -> hs-t200-3 (tenant 200)       [FAIL]
\

To amend this, check the current running iproute2 supports the vrftable
feature and, if not, just skip the entire test to avoid a failure.

v2: - remove dx[4/6] tests
    - test if vrftable is available in the installed iproute2 application
v1: https://patchwork.kernel.org/project/netdevbpf/patch/20260824091537.2305107-1-alessio.faina@canonical.com/
    - initial approach by testing DT[4/6] and DX[4/6]
    - test if DT4/DT6 are available in iproute2

Signed-off-by: Alessio Faina <alessio.faina@canonical.com>
---
 ./tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh  | 21 +++++++++++++++++++
 ./tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh  | 21 +++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh b/tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh
index a649dba3cb77..037e5fe1da2a 100755
--- a/tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh
+++ b/tools/testing/selftests/net/srv6_end_dt4_l3vpn_test.sh
@@ -469,12 +469,33 @@ if [ ! -x "$(command -v ip)" ]; then
 	exit $ksft_skip
 fi
 
+test_vrftable_supp_or_ksft_skip()
+{
+	local nsname
+
+	setup_ns nsname
+	ip netns exec "${nsname}" sh -c "echo 1 > /proc/sys/net/vrf/strict_mode"
+	ip -netns "${nsname}" link add vrf-100 type vrf table 100
+	ip -netns "${nsname}" link set vrf-100 up
+
+	if ! ip -netns "${nsname}" -6 route add fc00::1/128 \
+			encap seg6local action End.DT4 vrftable 100 dev vrf-100 2>/dev/null; then
+		cleanup_ns "${nsname}"
+		echo "SKIP: SRv6 End.DT4 vrftable not supported"
+		exit "${ksft_skip}"
+	fi
+
+	cleanup_ns "${nsname}"
+}
+
 modprobe vrf &>/dev/null
 if [ ! -e /proc/sys/net/vrf/strict_mode ]; then
         echo "SKIP: vrf sysctl does not exist"
         exit $ksft_skip
 fi
 
+test_vrftable_supp_or_ksft_skip
+
 cleanup &>/dev/null
 
 setup
diff --git a/tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh b/tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh
index e408406d8489..9a29e0d6c912 100755
--- a/tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh
+++ b/tools/testing/selftests/net/srv6_end_dt6_l3vpn_test.sh
@@ -479,12 +479,33 @@ if [ ! -x "$(command -v ip)" ]; then
 	exit $ksft_skip
 fi
 
+test_vrftable_supp_or_ksft_skip()
+{
+	local nsname
+
+	setup_ns nsname
+	ip netns exec "${nsname}" sh -c "echo 1 > /proc/sys/net/vrf/strict_mode"
+	ip -netns "${nsname}" link add vrf-100 type vrf table 100
+	ip -netns "${nsname}" link set vrf-100 up
+
+	if ! ip -netns "${nsname}" -6 route add fc00::1/128 \
+			encap seg6local action End.DT6 vrftable 100 dev vrf-100 2>/dev/null; then
+		cleanup_ns "${nsname}"
+		echo "SKIP: SRv6 End.DT6 vrftable not supported"
+		exit "${ksft_skip}"
+	fi
+
+	cleanup_ns "${nsname}"
+}
+
 modprobe vrf &>/dev/null
 if [ ! -e /proc/sys/net/vrf/strict_mode ]; then
         echo "SKIP: vrf sysctl does not exist"
         exit $ksft_skip
 fi
 
+test_vrftable_supp_or_ksft_skip
+
 cleanup &>/dev/null
 
 setup
-- 
2.43.0