Re: [PATCH nf] selftests: netfilter: add synproxy test

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Fri, Feb 04, 2022 at 02:02:33PM +0100, Florian Westphal wrote:
> Simple test for synproxy feature, iperf3 should be intercepted
> by synproxy netns, but connection should still succeed.

It would be great to have a test for synproxy map support too in a
follow up patch.

> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
>  tools/testing/selftests/netfilter/Makefile    |   2 +-
>  .../selftests/netfilter/nft_synproxy.sh       | 115 ++++++++++++++++++
>  2 files changed, 116 insertions(+), 1 deletion(-)
>  create mode 100755 tools/testing/selftests/netfilter/nft_synproxy.sh
> 
> diff --git a/tools/testing/selftests/netfilter/Makefile b/tools/testing/selftests/netfilter/Makefile
> index ffca314897c4..e4f845dd942b 100644
> --- a/tools/testing/selftests/netfilter/Makefile
> +++ b/tools/testing/selftests/netfilter/Makefile
> @@ -6,7 +6,7 @@ TEST_PROGS := nft_trans_stress.sh nft_fib.sh nft_nat.sh bridge_brouter.sh \
>  	nft_concat_range.sh nft_conntrack_helper.sh \
>  	nft_queue.sh nft_meta.sh nf_nat_edemux.sh \
>  	ipip-conntrack-mtu.sh conntrack_tcp_unreplied.sh \
> -	conntrack_vrf.sh
> +	conntrack_vrf.sh nft_synproxy.sh
>  
>  LDLIBS = -lmnl
>  TEST_GEN_FILES =  nf-queue
> diff --git a/tools/testing/selftests/netfilter/nft_synproxy.sh b/tools/testing/selftests/netfilter/nft_synproxy.sh
> new file mode 100755
> index 000000000000..09bb95c87198
> --- /dev/null
> +++ b/tools/testing/selftests/netfilter/nft_synproxy.sh
> @@ -0,0 +1,115 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +
> +# Kselftest framework requirement - SKIP code is 4.
> +ksft_skip=4
> +ret=0
> +
> +rnd=$(mktemp -u XXXXXXXX)
> +nsr="nsr-$rnd"	# synproxy machine
> +ns1="ns1-$rnd"  # iperf client
> +ns2="ns2-$rnd"  # iperf server
> +
> +checktool (){
> +	if ! $1 > /dev/null 2>&1; then
> +		echo "SKIP: Could not $2"
> +		exit $ksft_skip
> +	fi
> +}
> +
> +checktool "nft --version" "run test without nft tool"
> +checktool "ip -Version" "run test without ip tool"
> +checktool "iperf3 --version" "run test without iperf3"
> +checktool "ip netns add $nsr" "create net namespace"
> +
> +ip netns add $ns1
> +ip netns add $ns2
> +
> +cleanup() {
> +	ip netns pids $ns1 | xargs kill 2>/dev/null
> +	ip netns pids $ns2 | xargs kill 2>/dev/null
> +	ip netns del $ns1
> +	ip netns del $ns2
> +
> +	ip netns del $nsr
> +}
> +
> +trap cleanup EXIT
> +
> +ip link add veth0 netns $nsr type veth peer name eth0 netns $ns1
> +ip link add veth1 netns $nsr type veth peer name eth0 netns $ns2
> +
> +for dev in lo veth0 veth1; do
> +ip -net $nsr link set $dev up
> +done
> +
> +ip -net $nsr addr add 10.0.1.1/24 dev veth0
> +ip -net $nsr addr add 10.0.2.1/24 dev veth1
> +
> +ip netns exec $nsr sysctl -q net.ipv4.conf.veth0.forwarding=1
> +ip netns exec $nsr sysctl -q net.ipv4.conf.veth1.forwarding=1
> +ip netns exec $nsr sysctl -q net.netfilter.nf_conntrack_tcp_loose=0
> +
> +for n in $ns1 $ns2; do
> +  ip -net $n link set lo up
> +  ip -net $n link set eth0 up
> +done
> +ip -net $ns1 addr add 10.0.1.99/24 dev eth0
> +ip -net $ns2 addr add 10.0.2.99/24 dev eth0
> +ip -net $ns1 route add default via 10.0.1.1
> +ip -net $ns2 route add default via 10.0.2.1
> +
> +# test basic connectivity
> +if ! ip netns exec $ns1 ping -c 1 -q 10.0.2.99 > /dev/null; then
> +  echo "ERROR: $ns1 cannot reach $ns2" 1>&2
> +  exit 1
> +fi
> +
> +if ! ip netns exec $ns2 ping -c 1 -q 10.0.1.99 > /dev/null; then
> +  echo "ERROR: $ns2 cannot reach $ns1" 1>&2
> +  exit 1
> +fi
> +
> +ip netns exec $ns2 iperf3 -s > /dev/null 2>&1 &
> +# ip netns exec $nsr tcpdump -vvv -n -i veth1 tcp | head -n 10 &
> +
> +sleep 1
> +
> +ip netns exec $nsr nft -f - <<EOF
> +table inet filter {
> +   chain prerouting {
> +      type filter hook prerouting priority -300; policy accept;
> +      meta iif veth0 tcp flags syn counter notrack
> +   }
> +
> +  chain forward {
> +      type filter hook forward priority 0; policy accept;
> +
> +      ct state new,established counter accept
> +
> +      meta iif veth0 meta l4proto tcp ct state untracked,invalid synproxy mss 1460 sack-perm timestamp
> +
> +      ct state invalid counter drop
> +
> +      # make ns2 unreachable w.o. tcp synproxy
> +      tcp flags syn counter drop
> +   }
> +}
> +EOF
> +if [ $? -ne 0 ]; then
> +	echo "SKIP: Cannot add nft synproxy"
> +	exit $ksft_skip
> +fi
> +
> +ip netns exec $ns1 timeout 5 iperf3 -c 10.0.2.99 -n $((1 * 1024 * 1024)) > /dev/null
> +
> +if [ $? -ne 0 ]; then
> +	echo "FAIL: iperf3 returned an error" 1>&2
> +	ret=$?
> +	ip netns exec $nsr nft list ruleset
> +else
> +	echo "PASS: synproxy connection successful"
> +fi
> +
> +exit $ret
> -- 
> 2.34.1
>