Re: [PATCH v5 net-next 6/6] selftests: forwarding: add test of MAC-Auth Bypass to locked port tests

netdev
2022-09-22T20:35:15Z

On 2022-09-21 09:15, Ido Schimmel wrote:
> On Tue, Sep 20, 2022 at 11:29:12PM +0200, netdev@kapio-technology.com
> wrote:
>> I have made a blackhole selftest, which looks like this:
>>
>> test_blackhole_fdb()
>> {
>> RET=0
>>
>> check_blackhole_fdb_support || return 0
>>
>> tcpdump_start $h2
>> $MZ $h1 -q -t udp -a $h1 -b $h2
>
> I don't think you can give an interface name to '-a' and '-b'?
>
>> tcpdump_stop
>> tcpdump_show | grep -q udp
>> check_err $? "test_blackhole_fdb: No packet seen on initial"
>> tcpdump_cleanup
>>
>> bridge fdb add `mac_get $h2` dev br0 blackhole
>> bridge fdb show dev br0 | grep -q "blackhole"
>
> Make this grep more specific so that we are sure it is the entry user
> space installed. Something like this:
>
> bridge fdb get `mac_get $h2` br br0 | grep -q blackhole
>
>> check_err $? "test_blackhole_fdb: No blackhole FDB entry
>> found"
>>
>> tcpdump_start $h2
>> $MZ $h1 -q -t udp -a $h1 -b $h2
>> tcpdump_stop
>> tcpdump_show | grep -q udp
>> check_fail $? "test_blackhole_fdb: packet seen with blackhole
>> fdb
>> entry"
>> tcpdump_cleanup
>
> The tcpdump filter is not specific enough. It can catch other UDP
> packets (e.g., multicast) being received by $h2. Anyway, to be sure the
> feature works as expected we need to make sure that the packets are not
> even egressing $swp2. Checking that they are not received by $h2 is not
> enough. See this (untested) suggestion [1] that uses a tc filter on the
> egress of $swp2.
>
>>
>> bridge fdb del `mac_get $h2` dev br0 blackhole
>> bridge fdb show dev br0 | grep -q "blackhole"
>> check_fail $? "test_blackhole_fdb: Blackhole FDB entry not
>> deleted"
>>
>> tcpdump_start $h2
>> $MZ $h1 -q -t udp -a $h1 -b $h2
>> tcpdump_stop
>> tcpdump_show | grep -q udp
>> check_err $? "test_blackhole_fdb: No packet seen after
>> removing
>> blackhole FDB entry"
>> tcpdump_cleanup
>>
>> log_test "Blackhole FDB entry test"
>> }
>>
>> the setup is simple and is the same as in bridge_sticky_fdb.sh.
>>
>> Does the test look sound or is there obvious mistakes?
>
> [1]
> blackhole_fdb()
> {
> RET=0
>
> tc filter add dev $swp2 egress protocol ip pref 1 handle 1 flower \
> dst_ip 192.0.2.2 ip_proto udp dst_port 12345 action pass
>
> $MZ $h1 -c 1 -p 128 -t udp "sp=54321,dp=12345" \
> -a own -b `mac_get $h2` -A 192.0.2.1 -B 192.0.2.2 -q
>
> tc_check_packets "dev $swp2 egress" 1 1
> check_err $? "Packet not seen on egress before adding blackhole entry"
>
> bridge fdb add `mac_get $h2` dev br0 blackhole
> bridge fdb get `mac_get $h2` br br0 | grep -q blackhole
> check_err $? "Blackhole entry not found"
>
> $MZ $h1 -c 1 -p 128 -t udp "sp=54321,dp=12345" \
> -a own -b `mac_get $h2` -A 192.0.2.1 -B 192.0.2.2 -q
>
> tc_check_packets "dev $swp2 egress" 1 1
> check_err $? "Packet seen on egress after adding blackhole entry"
>
> # Check blackhole entries can be replaced.
> bridge fdb replace `mac_get $h2` dev $swp2 master static
> bridge fdb get `mac_get $h2` br br0 | grep -q blackhole
> check_fail $? "Blackhole entry found after replacement"
>
> $MZ $h1 -c 1 -p 128 -t udp "sp=54321,dp=12345" \
> -a own -b `mac_get $h2` -A 192.0.2.1 -B 192.0.2.2 -q
>
> tc_check_packets "dev $swp2 egress" 1 2
> check_err $? "Packet not seen on egress after replacing blackhole
> entry"
>
> bridge fdb del `mac_get $h2` dev $swp2 master static
> tc filter del dev $swp2 egress protocol ip pref 1 handle 1 flower
>
> log_test "Blackhole FDB entry"
> }

Thx, looks good.
I have tried to run the test as far as I can manually, but I don't seem
to have 'busywait' in the system, which tc_check_packets() depends on,
and I couldn't find any 'busywait' in Buildroot.