netdev - Re: [net-next v3 7/7] selftests: openvswitch: add explicit drop testcase

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Date: Wed, 9 Aug 2023 09:02:12 +0200
From: Adrian Moreno <amorenoz@...hat.com>
To: Aaron Conole <aconole@...hat.com>
Cc: netdev@...r.kernel.org, i.maximets@....org, eric@...ver.life,
 dev@...nvswitch.org
Subject: Re: [net-next v3 7/7] selftests: openvswitch: add explicit drop
 testcase



On 8/8/23 17:02, Aaron Conole wrote:
> Adrian Moreno <amorenoz@...hat.com> writes:
> 
>> Make ovs-dpctl.py support explicit drops as:
>> "drop" -> implicit empty-action drop
>> "drop(0)" -> explicit non-error action drop
> 
> I also suggest a test in netlink_checks to make sure drop can't be
> followed by additional actions.  Something like:
> 
>    3,drop(0),2
> 
> which should generate a NL message that has the drop attribute with
> additional action data following it.

Ack, will do.

The check I've added in flow_netlink.c does not include any custom message. Just 
returning -EINVAL in __ovs_nla_copy_actions() ends up printing "Flow actions may 
not be safe on all matching packets" to dmesg. Maybe it's too generic or even 
misleading in some cases but I saw other action verifications do the same so I 
thought it might be kind of expected at this point.

Do you think a custom message (in addition to the generic one) is needed?

Thanks.
--
Adrián

> 
>> "drop(42)" -> explicit error action drop
>>
>> Signed-off-by: Adrian Moreno <amorenoz@...hat.com>
>> ---
>>   .../selftests/net/openvswitch/openvswitch.sh  | 25 +++++++++++++++++++
>>   .../selftests/net/openvswitch/ovs-dpctl.py    | 21 ++++++++++++----
>>   2 files changed, 41 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
>> index a10c345f40ef..c568ba1b7900 100755
>> --- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
>> +++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
>> @@ -217,6 +217,31 @@ test_drop_reason() {
>>   		return 1
>>   	fi
>>   
>> +	# Drop UDP 6000 traffic with an explicit action and an error code.
>> +	ovs_add_flow "test_drop_reason" dropreason \
>> +		"in_port(1),eth(),eth_type(0x0800),ipv4(src=172.31.110.10,proto=17),udp(dst=6000)" \
>> +                'drop(42)'
>> +	# Drop UDP 7000 traffic with an explicit action with no error code.
>> +	ovs_add_flow "test_drop_reason" dropreason \
>> +		"in_port(1),eth(),eth_type(0x0800),ipv4(src=172.31.110.10,proto=17),udp(dst=7000)" \
>> +                'drop(0)'
>> +
>> +	ovs_drop_record_and_run \
>> +            "test_drop_reason" ip netns exec client nc -i 1 -zuv 172.31.110.20 6000
>> +	ovs_drop_reason_count 0x30004 # OVS_DROP_EXPLICIT_ACTION_ERROR
>> +	if [[ "$?" -ne "1" ]]; then
>> +		info "Did not detect expected explicit error drops: $?"
>> +		return 1
>> +	fi
>> +
>> +	ovs_drop_record_and_run \
>> +            "test_drop_reason" ip netns exec client nc -i 1 -zuv 172.31.110.20 7000
>> +	ovs_drop_reason_count 0x30003 # OVS_DROP_EXPLICIT_ACTION
>> +	if [[ "$?" -ne "1" ]]; then
>> +		info "Did not detect expected explicit drops: $?"
>> +		return 1
>> +	fi
>> +
>>   	return 0
>>   }
>>   
>> diff --git a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
>> index 5fee330050c2..912dc8c49085 100644
>> --- a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
>> +++ b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
>> @@ -449,7 +449,7 @@ class ovsactions(nla):
>>                   elif field[0] == "OVS_ACTION_ATTR_TRUNC":
>>                       print_str += "trunc(%d)" % int(self.get_attr(field[0]))
>>                   elif field[0] == "OVS_ACTION_ATTR_DROP":
>> -                    print_str += "drop"
>> +                    print_str += "drop(%d)" % int(self.get_attr(field[0]))
>>               elif field[1] == "flag":
>>                   if field[0] == "OVS_ACTION_ATTR_CT_CLEAR":
>>                       print_str += "ct_clear"
>> @@ -471,10 +471,21 @@ class ovsactions(nla):
>>           while len(actstr) != 0:
>>               parsed = False
>>               if actstr.startswith("drop"):
>> -                # for now, drops have no explicit action, so we
>> -                # don't need to set any attributes.  The final
>> -                # act of the processing chain will just drop the packet
>> -                return
>> +                # If no reason is provided, the implicit drop is used (i.e no
>> +                # action). If some reason is given, an explicit action is used.
>> +                actstr, reason = parse_extract_field(
>> +                    actstr,
>> +                    "drop(",
>> +                    "([0-9]+)",
>> +                    lambda x: int(x, 0),
>> +                    False,
>> +                    None,
>> +                )
>> +                if reason is not None:
>> +                    self["attrs"].append(["OVS_ACTION_ATTR_DROP", reason])
>> +                    parsed = True
>> +                else:
>> +                    return
>>   
>>               elif parse_starts_block(actstr, "^(\d+)", False, True):
>>                   actstr, output = parse_extract_field(
>