EDP_MULTICAST_ADDR in edp.h seems not a multicast address

[qiuchengxuan]

Bug description

Lldpd will call SIOCADDMULTI ioctl to add multicast address which is not really a multicast address when EDP enabled.

Steps to reproduce the problem

Platform specific, start LLDPD with edp enabled, some ethernet driver will complain not a multicast address

Expected outcome

lldpd started with no error

Current outcome

After executing the above steps, lldpd crashed. Here is the end of
the output of lldpd -ddddd before the crash:

root@OpenWrt:/# /usr/sbin/lldpd -d -e -M 4
2021-04-13T07:44:46 [WARN/priv] no privilege separation available
2021-04-13T07:44:46 [INFO/main] protocol LLDP enabled
2021-04-13T07:44:46 [INFO/main] protocol CDPv1 disabled
2021-04-13T07:44:46 [[ 2864.327865] cpu 0: ! MAJOR FM-MAC Error [CPU00, drivers/net/ethernet/freescale/sdk_fman/Peripherals/FM/MAC/memac.c:797 MemacAddHashMacAddress]: Unsupported Operation;
INFO/main] p[ 2864.327870] cpu 0: Unicast Address
rotocol CDPv2 di[ 2864.343723] cpu 0:
sabled
2021-04-[ 2864.352077] FM_MAC_AddHashMacAddr() = 0x00050026
13T07:44:46  2864.358088] fsl_dpa soc:fsl,dpaa:ethernet@1 eth3: mac_dev->set_multi() = -38
34m[INFO/main] protocol SONMP disabled
2021-04-13T07:44:46 [INFO/main] protocol EDP enabled
2021-04-13T07:44:46 [INFO/main] protocol FDP disabled
2021-04-13T07:44:46 [INFO/[ 2864.383794] cpu 0: ! MAJOR FM-MAC Error [CPU00, drivers/net/ethernet/freescale/sdk_fman/Peripherals/FM/MAC/memac.c:797 MemacAddHashMacAddress]: Unsupported Operation;
event] libev[ 2864.383796] cpu 0: Unicast Address
ent 2.1.11-stabl[ 2864.399525] cpu 0:
e initialized wi[ 2864.407871] FM_MAC_AddHashMacAddr() = 0x00050026
[ 2864.413878] fsl_dpa soc:fsl,dpaa:ethernet@2 eth0: mac_dev->set_multi() = -38

[ 2864.439778] cpu 0: ! MAJOR FM-MAC Error [CPU00, drivers/net/ethernet/freescale/sdk_fman/Peripherals/FM/MAC/memac.c:797 MemacAddHashMacAddress]: Unsupported Operation;
[ 2864.439781] cpu 0: Unicast Address
[ 2864.454734] cpu 0:
[ 2864.460319] FM_MAC_AddHashMacAddr() = 0x00050026

Additional information

Spotted on version 1.0.3, and still exists in master

[vincentbernat]

Humm, this was never reported until now and it works as expected in software: Linux does not really care that the MAC address is multicast or not and the NIC is listening to this MAC address as a result of the registration. On Linux, it is possible to add more MAC addresses through Netlink with recent kernels. And I need to find the equivalent for other OS.

[vincentbernat]

If the main problem is only the crash, can you provide a coredump?

[qiuchengxuan]

It doesn't crash, just kernel error

[qiuchengxuan]

It seems to be NIC driver specific, most driver won't care whether it's a multicast address except FSL DPAA SDK

[vincentbernat]

Does EDP work?

If not, can you try to use bridge fdb add 00:e0:2b:00:00:00 dev eth0 and see if you are able to receive EDP packets?

[qiuchengxuan]

I don't know, I encountered this problem simply because it's default enabled in OpenWRT, although I don't think so because I had a glance to driver source which takes no further action but returned error.

[vincentbernat]

Is EDP enabled by default?

[qiuchengxuan]

In OpenWRT, I mean

https://github.com/openwrt/openwrt/blob/master/package/network/services/lldpd/files/lldpd.config

[vincentbernat]

After thinking a bit about it, I have decided to not implement it because:

• while the ioctl() says "multicast", it does work for unicast across many OS and platforms, it seems that the driver should not refuse to program this address because it is not multicast,
• registering an unicast address can only be done using Netlink with a fair amount of code and this code will be running as root,
• EDP/FDP are a protocol from the past, maybe it would be safer for OpenWRT to not enable them by default (a few bugs have been fixed in the parsing code recently).

[qiuchengxuan]

I see, indeed OpenWRT should not enable this by default