Re: [ovs-dev] [PATCH net-next 4/4] selftests: openvswitch: add ct-nat test case with ipv4

[Adrian Moreno <amorenoz@redhat.com>]

On 6/28/23 18:27, Aaron Conole wrote:
> Building on the previous work, add a very simplistic NAT case
> using ipv4.  This just tests dnat transformation
> 
> Signed-off-by: Aaron Conole <aconole@redhat.com>

Hi Aaron,

I know that the goal is not to support the full syntax, and that nat is a 
specially convoluted action, so I'm just commenting on the low-hanging fruits 
(see below).

> ---
>   .../selftests/net/openvswitch/openvswitch.sh  | 64 +++++++++++++++++++
>   .../selftests/net/openvswitch/ovs-dpctl.py    | 60 +++++++++++++++++
>   2 files changed, 124 insertions(+)
> 
> diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
> index 40a66c72af0f0..dced4f612a78c 100755
> --- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
> +++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
> @@ -14,6 +14,7 @@ tests="
>   	arp_ping				eth-arp: Basic arp ping between two NS
>   	ct_connect_v4				ip4-ct-xon: Basic ipv4 tcp connection using ct
>   	connect_v4				ip4-xon: Basic ipv4 ping between two NS
> +	nat_connect_v4				ip4-nat-xon: Basic ipv4 tcp connection via NAT
>   	netlink_checks				ovsnl: validate netlink attrs and settings
>   	upcall_interfaces			ovs: test the upcall interfaces"
>   
> @@ -300,6 +301,69 @@ test_connect_v4 () {
>   	return 0
>   }
>   
> +# nat_connect_v4 test
> +#  - client has 1500 byte MTU
> +#  - server has 1500 byte MTU
> +#  - use ICMP to ping in each direction
> +#  - only allow CT state stuff to pass through new in c -> s
> +test_nat_connect_v4 () {
> +	which nc >/dev/null 2>/dev/null || return $ksft_skip
> +
> +	sbx_add "test_nat_connect_v4" || return $?
> +
> +	ovs_add_dp "test_nat_connect_v4" nat4 || return 1
> +	info "create namespaces"
> +	for ns in client server; do
> +		ovs_add_netns_and_veths "test_nat_connect_v4" "nat4" "$ns" \
> +		    "${ns:0:1}0" "${ns:0:1}1" || return 1
> +	done
> +
> +	ip netns exec client ip addr add 172.31.110.10/24 dev c1
> +	ip netns exec client ip link set c1 up
> +	ip netns exec server ip addr add 172.31.110.20/24 dev s1
> +	ip netns exec server ip link set s1 up
> +
> +	ip netns exec client ip route add default via 172.31.110.20
> +
> +	ovs_add_flow "test_nat_connect_v4" nat4 \
> +		'in_port(1),eth(),eth_type(0x0806),arp()' '2' || return 1
> +	ovs_add_flow "test_nat_connect_v4" nat4 \
> +		'in_port(2),eth(),eth_type(0x0806),arp()' '1' || return 1
> +	ovs_add_flow "test_nat_connect_v4" nat4 \
> +		"ct_state(-trk),in_port(1),eth(),eth_type(0x0800),ipv4(dst=192.168.0.20)" \
> +		"ct(commit,nat(dst=172.31.110.20)),recirc(0x1)"
> +	ovs_add_flow "test_nat_connect_v4" nat4 \
> +		"ct_state(-trk),in_port(2),eth(),eth_type(0x0800),ipv4()" \
> +		"ct(commit,nat),recirc(0x2)"
> +
> +	ovs_add_flow "test_nat_connect_v4" nat4 \
> +		"recirc_id(0x1),ct_state(+trk-inv),in_port(1),eth(),eth_type(0x0800),ipv4()" "2"
> +	ovs_add_flow "test_nat_connect_v4" nat4 \
> +		"recirc_id(0x2),ct_state(+trk-inv),in_port(2),eth(),eth_type(0x0800),ipv4()" "1"
> +
> +	# do a ping
> +	ovs_sbx "test_nat_connect_v4" ip netns exec client ping 192.168.0.20 -c 3 || return 1
> +
> +	# create an echo server in 'server'
> +	echo "server" | \
> +		ovs_netns_spawn_daemon "test_nat_connect_v4" "server" \
> +				nc -lvnp 4443
> +	ovs_sbx "test_nat_connect_v4" ip netns exec client nc -i 1 -zv 192.168.0.20 4443 || return 1
> +
> +	# Now test in the other direction (should fail)
> +	echo "client" | \
> +		ovs_netns_spawn_daemon "test_nat_connect_v4" "client" \
> +				nc -lvnp 4443
> +	ovs_sbx "test_nat_connect_v4" ip netns exec client nc -i 1 -zv 172.31.110.10 4443
> +	if [ $? == 0 ]; then
> +	   info "connect to client was successful"
> +	   return 1
> +	fi
> +
> +	info "done..."
> +	return 0
> +}
> +
>   # netlink_validation
>   # - Create a dp
>   # - check no warning with "old version" simulation
> diff --git a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
> index 704cb4adf79a9..12ba5265b88fb 100644
> --- a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
> +++ b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
> @@ -511,6 +511,66 @@ class ovsactions(nla):
>                           else:
>                               ctact["attrs"].append([scan[1], None])
>                           actstr = actstr[strspn(actstr, ", ") :]
> +                    # it seems strange to put this here, but nat() is a complex
> +                    # sub-action and this lets it sit anywhere in the ct() action
> +                    if actstr.startswith("nat"):
> +                        actstr = actstr[3:]
> +                        natact = ovsactions.ctact.natattr()
> +
> +                        if actstr.startswith("("):
> +                            t = None
> +                            actstr = actstr[1:]
> +                            if actstr.startswith("src"):
> +                                t = "OVS_NAT_ATTR_SRC"
> +                                actstr = actstr[3:]
> +                            elif actstr.startswith("dst"):
> +                                t = "OVS_NAT_ATTR_DST"
> +                                actstr = actstr[3:]
> +
> +                            actstr, ip_block_min = parse_extract_field(
> +                                actstr, "=", "([0-9a-fA-F:\.]+)", str, False
> +                            )
> +                            actstr, ip_block_max = parse_extract_field(
> +                                actstr, "-", "([0-9a-fA-F:\.]+)", str, False
> +                            )

Having the ":" character here makes this line parse the port as well (i.e: 
1.1.1.1:6789 as ip_block_max) which then makes ip address parsing fail.


> +                            actstr, proto_min = parse_extract_field(
> +                                actstr, ":", "(\d+)", int, False
> +                            )
> +                            actstr, proto_max = parse_extract_field(
> +                                actstr, "-", "(\d+)", int, False
> +                            )
> +                            if t is not None:
> +                                natact["attrs"].append([t, None])
> +
> +                                if ip_block_min is not None:
> +                                    natact["attrs"].append(
> +                                        ["OVS_NAT_ATTR_IP_MIN", ip_block_min]
> +                                    )
> +                                if ip_block_max is not None:
> +                                    natact["attrs"].append(
> +                                        ["OVS_NAT_ATTR_IP_MAX", ip_block_max]
> +                                    )
> +                                if proto_min is not None:
> +                                    natact["attrs"].append(
> +                                        ["OVS_NAT_ATTR_PROTO_MIN", proto_min]
> +                                    )
> +                                if proto_max is not None:
> +                                    natact["attrs"].append(
> +                                        ["OVS_NAT_ATTR_PROTO_MAX", proto_max]
> +                                    )
> +
> +                            for natscan in (
> +                                ("persist", "OVS_NAT_ATTR_PERSISTENT"),
> +                                ("hash", "OVS_NAT_ATTR_PROTO_HASH"),
> +                                ("random", "OVS_NAT_ATTR_PROTO_RANDOM"),
> +                            ):

I think this is not taking into account the comma that separates ip:port from 
these keywords. A possible solution would be to add it to the natscan (e.g: 
s/persist/,persist/).

> +                                if actstr.startswith(natscan[0]):
> +                                    actstr = actstr[len(natscan[0]) :]
> +                                    natact["attrs"].append([natscan[1], None])
> +                                    actstr = actstr[strspn(actstr, ", ") :]
> +
> +                        ctact["attrs"].append(["OVS_CT_ATTR_NAT", natact])
> +                        actstr = actstr[strspn(actstr, ",) ") :]
>   
>                   self["attrs"].append(["OVS_ACTION_ATTR_CT", ctact])
>                   actstr = actstr[strspn(actstr, "), ") :]

-- 
Adrián Moreno