Use nft by default if it's supported, as nft is the replacement for iptables,
which is used by default in some releases. Additionally, iptables is dropped
in some releases.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
CC nft developers to see if there are any easier configurations,
as I'm not very familiar with nft commands.
---
 tools/testing/selftests/wireguard/netns.sh | 63 ++++++++++++++++++----
 1 file changed, 53 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/wireguard/netns.sh b/tools/testing/selftests/wireguard/netns.sh
index 405ff262ca93..4e29c1a7003c 100755
--- a/tools/testing/selftests/wireguard/netns.sh
+++ b/tools/testing/selftests/wireguard/netns.sh
@@ -44,6 +44,7 @@ sleep() { read -t "$1" -N 1 || true; }
 waitiperf() { pretty "${1//*-}" "wait for iperf:${3:-5201} pid $2"; while [[ $(ss -N "$1" -tlpH "sport = ${3:-5201}") != *\"iperf3\",pid=$2,fd=* ]]; do sleep 0.1; done; }
 waitncatudp() { pretty "${1//*-}" "wait for udp:1111 pid $2"; while [[ $(ss -N "$1" -ulpH 'sport = 1111') != *\"ncat\",pid=$2,fd=* ]]; do sleep 0.1; done; }
 waitiface() { pretty "${1//*-}" "wait for $2 to come up"; ip netns exec "$1" bash -c "while [[ \$(< \"/sys/class/net/$2/operstate\") != up ]]; do read -t .1 -N 0 || true; done;"; }
+use_nft() { nft --version &> /dev/null; }
 
 cleanup() {
 	set +e
@@ -196,13 +197,23 @@ ip1 link set wg0 mtu 1300
 ip2 link set wg0 mtu 1300
 n1 wg set wg0 peer "$pub2" endpoint 127.0.0.1:2
 n2 wg set wg0 peer "$pub1" endpoint 127.0.0.1:1
-n0 iptables -A INPUT -m length --length 1360 -j DROP
+if use_nft; then
+	n0 nft add table inet filter
+	n0 nft add chain inet filter INPUT { type filter hook input priority filter \; policy accept \; }
+	n0 nft add rule inet filter INPUT meta length 1360 counter drop
+else
+	n0 iptables -A INPUT -m length --length 1360 -j DROP
+fi
 n1 ip route add 192.168.241.2/32 dev wg0 mtu 1299
 n2 ip route add 192.168.241.1/32 dev wg0 mtu 1299
 n2 ping -c 1 -W 1 -s 1269 192.168.241.1
 n2 ip route delete 192.168.241.1/32 dev wg0 mtu 1299
 n1 ip route delete 192.168.241.2/32 dev wg0 mtu 1299
-n0 iptables -F INPUT
+if use_nft; then
+	n0 nft delete table inet filter
+else
+	n0 iptables -F INPUT
+fi
 
 ip1 link set wg0 mtu $orig_mtu
 ip2 link set wg0 mtu $orig_mtu
@@ -334,7 +345,13 @@ waitiface $netns2 veths
 n0 bash -c 'printf 1 > /proc/sys/net/ipv4/ip_forward'
 n0 bash -c 'printf 2 > /proc/sys/net/netfilter/nf_conntrack_udp_timeout'
 n0 bash -c 'printf 2 > /proc/sys/net/netfilter/nf_conntrack_udp_timeout_stream'
-n0 iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -d 10.0.0.0/24 -j SNAT --to 10.0.0.1
+if use_nft; then
+	n0 nft add table inet nat
+	n0 nft add chain inet nat POSTROUTING { type nat hook postrouting priority srcnat\; policy accept \; }
+	n0 nft add rule inet nat POSTROUTING ip saddr 192.168.1.0/24 ip daddr 10.0.0.0/24 counter snat to 10.0.0.1
+else
+	n0 iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -d 10.0.0.0/24 -j SNAT --to 10.0.0.1
+fi
 
 n1 wg set wg0 peer "$pub2" endpoint 10.0.0.100:2 persistent-keepalive 1
 n1 ping -W 1 -c 1 192.168.241.2
@@ -348,10 +365,20 @@ n1 wg set wg0 peer "$pub2" persistent-keepalive 0
 # Test that sk_bound_dev_if works
 n1 ping -I wg0 -c 1 -W 1 192.168.241.2
 # What about when the mark changes and the packet must be rerouted?
-n1 iptables -t mangle -I OUTPUT -j MARK --set-xmark 1
+if use_nft; then
+	n1 nft add table inet mangle
+	n1 nft add chain inet mangle OUTPUT { type route hook output priority mangle\; policy accept \; }
+	n1 nft add rule inet mangle OUTPUT counter meta mark set 0x1
+else
+	n1 iptables -t mangle -I OUTPUT -j MARK --set-xmark 1
+fi
 n1 ping -c 1 -W 1 192.168.241.2 # First the boring case
 n1 ping -I wg0 -c 1 -W 1 192.168.241.2 # Then the sk_bound_dev_if case
-n1 iptables -t mangle -D OUTPUT -j MARK --set-xmark 1
+if use_nft; then
+	n1 nft delete table inet mangle
+else
+	n1 iptables -t mangle -D OUTPUT -j MARK --set-xmark 1
+fi
 
 # Test that onion routing works, even when it loops
 n1 wg set wg0 peer "$pub3" allowed-ips 192.168.242.2/32 endpoint 192.168.241.2:5
@@ -385,16 +412,32 @@ n1 ping -W 1 -c 100 -f 192.168.99.7
 n1 ping -W 1 -c 100 -f abab::1111
 
 # Have ns2 NAT into wg0 packets from ns0, but return an icmp error along the right route.
-n2 iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -d 192.168.241.0/24 -j SNAT --to 192.168.241.2
-n0 iptables -t filter -A INPUT \! -s 10.0.0.0/24 -i vethrs -j DROP # Manual rpfilter just to be explicit.
+if use_nft; then
+	n2 nft add table inet nat
+	n2 nft add chain inet nat POSTROUTING { type nat hook postrouting priority srcnat\; policy accept \; }
+	n2 nft add rule inet nat POSTROUTING ip saddr 10.0.0.0/24 ip daddr 192.168.241.0/24 counter snat to 192.168.241.2
+
+	n0 nft add table inet filter
+	n0 nft add chain inet filter INPUT { type filter hook input priority filter \; policy accept \; }
+	n0 nft add rule inet filter INPUT iifname "vethrs" ip saddr != 10.0.0.0/24 counter drop
+else
+	n2 iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -d 192.168.241.0/24 -j SNAT --to 192.168.241.2
+	n0 iptables -t filter -A INPUT \! -s 10.0.0.0/24 -i vethrs -j DROP # Manual rpfilter just to be explicit.
+fi
 n2 bash -c 'printf 1 > /proc/sys/net/ipv4/ip_forward'
 ip0 -4 route add 192.168.241.1 via 10.0.0.100
 n2 wg set wg0 peer "$pub1" remove
 [[ $(! n0 ping -W 1 -c 1 192.168.241.1 || false) == *"From 10.0.0.100 icmp_seq=1 Destination Host Unreachable"* ]]
 
-n0 iptables -t nat -F
-n0 iptables -t filter -F
-n2 iptables -t nat -F
+if use_nft; then
+	n0 nft delete table inet nat
+	n0 nft delete table inet filter
+	n2 nft delete table inet nat
+else
+	n0 iptables -t nat -F
+	n0 iptables -t filter -F
+	n2 iptables -t nat -F
+fi
 ip0 link del vethrc
 ip0 link del vethrs
 ip1 link del wg0
-- 
2.46.0

Hi Liu Hangbin,

On Thu, Nov 07, 2024 at 02:54:38AM +0000, Hangbin Liu wrote:
> Use nft by default if it's supported, as nft is the replacement for iptables,
> which is used by default in some releases. Additionally, iptables is dropped
> in some releases.
> 
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> ---
> CC nft developers to see if there are any easier configurations,
> as I'm not very familiar with nft commands.

Basically looks good, just a few minor remarks:

> ---
>  tools/testing/selftests/wireguard/netns.sh | 63 ++++++++++++++++++----
>  1 file changed, 53 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/testing/selftests/wireguard/netns.sh b/tools/testing/selftests/wireguard/netns.sh
> index 405ff262ca93..4e29c1a7003c 100755
> --- a/tools/testing/selftests/wireguard/netns.sh
> +++ b/tools/testing/selftests/wireguard/netns.sh
> @@ -44,6 +44,7 @@ sleep() { read -t "$1" -N 1 || true; }
>  waitiperf() { pretty "${1//*-}" "wait for iperf:${3:-5201} pid $2"; while [[ $(ss -N "$1" -tlpH "sport = ${3:-5201}") != *\"iperf3\",pid=$2,fd=* ]]; do sleep 0.1; done; }
>  waitncatudp() { pretty "${1//*-}" "wait for udp:1111 pid $2"; while [[ $(ss -N "$1" -ulpH 'sport = 1111') != *\"ncat\",pid=$2,fd=* ]]; do sleep 0.1; done; }
>  waitiface() { pretty "${1//*-}" "wait for $2 to come up"; ip netns exec "$1" bash -c "while [[ \$(< \"/sys/class/net/$2/operstate\") != up ]]; do read -t .1 -N 0 || true; done;"; }
> +use_nft() { nft --version &> /dev/null; }
>  
>  cleanup() {
>  	set +e
> @@ -196,13 +197,23 @@ ip1 link set wg0 mtu 1300
>  ip2 link set wg0 mtu 1300
>  n1 wg set wg0 peer "$pub2" endpoint 127.0.0.1:2
>  n2 wg set wg0 peer "$pub1" endpoint 127.0.0.1:1
> -n0 iptables -A INPUT -m length --length 1360 -j DROP
> +if use_nft; then
> +	n0 nft add table inet filter

Using inet family captures IPv6 traffic, too. You don't seem to
explicitly configure it, but the usual auto-config traffic may offset
rule counters. If you care about such side-effects, you may want to use
ip family instead.

Tables are family-specific, but generic otherwise. So you could add a
table for testing in each netns up front:

| if use_nft; then
| 	n0 nft add table ip wgtest
| 	n1 nft add table ip wgtest
| 	n2 nft add table ip wgtest
| fi

> +	n0 nft add chain inet filter INPUT { type filter hook input priority filter \; policy accept \; }
> +	n0 nft add rule inet filter INPUT meta length 1360 counter drop
> +else
> +	n0 iptables -A INPUT -m length --length 1360 -j DROP
> +fi
>  n1 ip route add 192.168.241.2/32 dev wg0 mtu 1299
>  n2 ip route add 192.168.241.1/32 dev wg0 mtu 1299
>  n2 ping -c 1 -W 1 -s 1269 192.168.241.1
>  n2 ip route delete 192.168.241.1/32 dev wg0 mtu 1299
>  n1 ip route delete 192.168.241.2/32 dev wg0 mtu 1299
> -n0 iptables -F INPUT
> +if use_nft; then
> +	n0 nft delete table inet filter

Here just flush the table (drops only the rules):

| n0 nft flush table ip wgtest

Cheers, Phil