selftests/net: packetdrill: run in netns and expand config

Run packetdrill tests inside netns.
They may change system settings, such as sysctl.

Also expand config with a few more needed CONFIGs.

Link: https://lore.kernel.org/netdev/20240910152640.429920be@kernel.org/Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240912005317.1253001-2-willemdebruijn.kernel@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/packetdrill/config

 CONFIG_IPV6=y
+CONFIG_HZ_1000=y
+CONFIG_HZ=1000
+CONFIG_NET_NS=y
 CONFIG_NET_SCH_FIFO=y
 CONFIG_PROC_SYSCTL=y
+CONFIG_SYN_COOKIES=y
+CONFIG_TCP_CONG_CUBIC=y
 CONFIG_TCP_MD5SIG=y
 CONFIG_TUN=y

tools/testing/selftests/net/packetdrill/ksft_runner.sh

@@ -33,9 +33,9 @@ fi
 ktap_print_header
 ktap_set_plan 2
 
-packetdrill ${ipv4_args[@]} $(basename $script) > /dev/null \
+unshare -n packetdrill ${ipv4_args[@]} $(basename $script) > /dev/null \
 	&& ktap_test_pass "ipv4" || ktap_test_fail "ipv4"
-packetdrill ${ipv6_args[@]} $(basename $script) > /dev/null \
+unshare -n packetdrill ${ipv6_args[@]} $(basename $script) > /dev/null \
 	&& ktap_test_pass "ipv6" || ktap_test_fail "ipv6"
 
 ktap_finished