netdev - Re: [PATCHv2 net-next 2/2] selftests: add a selftest for directed broadcast forwarding

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Date:   Tue, 3 Jul 2018 13:23:41 -0600
From:   David Ahern <dsahern@...il.com>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, davem <davem@...emloft.net>,
        Davide Caratti <dcaratti@...hat.com>,
        Ido Schimmel <idosch@...sch.org>
Subject: Re: [PATCHv2 net-next 2/2] selftests: add a selftest for directed
 broadcast forwarding

On 7/3/18 5:36 AM, Xin Long wrote:
> On Mon, Jul 2, 2018 at 11:12 PM, David Ahern <dsahern@...il.com> wrote:
>> On 7/2/18 12:30 AM, Xin Long wrote:
>>> +ping_ipv4()
>>> +{
>>> +     sysctl_set net.ipv4.icmp_echo_ignore_broadcasts 0
>>> +     bc_forwarding_disable
>>> +     ping_test $h1 198.51.100.255
>>> +
>>> +     iptables -A INPUT -i vrf-r1 -p icmp -j DROP
>>> +     bc_forwarding_restore
>>> +     bc_forwarding_enable
>>> +     ping_test $h1 198.51.100.255
>>> +
>>> +     bc_forwarding_restore
>>> +     iptables -D INPUT -i vrf-r1 -p icmp -j DROP
>>> +     sysctl_restore net.ipv4.icmp_echo_ignore_broadcasts
>>> +}
>>
>> Both tests fail for me:
>> TEST: ping                                              [FAIL]
>> TEST: ping                                              [FAIL]
> I think 'ip vrf exec ...' is not working in your env, while
> the testing is using "ip vrf exec vrf-h1 ping ..."
> 
> You can test it by:
> # ip link add dev vrf-test type vrf table 1111
> # ip vrf exec vrf-test ls

well, that's embarrassing. yes, I updated ip and forgot to apply the bpf
workaround to define the syscall number (not defined in jessie).

> 
>>
>> Why the need for the iptables rule?
> This iptables rule is to block the echo_request packet going to
> route's local_in.
> When bc_forwarding is NOT doing forwarding well but the packet
> goes to the route's local_in, it will fail.
> 
> Without this rule, the 2nd ping will always succeed, we can't tell the
> echo_reply is from route or h2.
> 
> Or you have a better way to test this?

your commands are not a proper test. The test should succeed and fail
based on the routing lookup, not iptables rules.

> 
>>
>> And, PAUSE_ON_FAIL is not working to take a look at why tests are
>> failing. e.g.,
>>
>> PAUSE_ON_FAIL=yes ./router_broadcast.sh
>>
>> just continues on. Might be something with the infrastructure scripts.
> Yes, in ./router_broadcast.sh, it loads lib.sh where it loads forwarding.config
> where it has "PAUSE_ON_FAIL=no", which would override your
> "PAUSE_ON_FAIL=yes".
> 

ack. bit by that as well.