Permission Denied - multicast_snooping

[vinsworldcom]

Running on Docker for Windows with WSL2 integration, getting:

root@4177eaff57f1:/emane-sims-etce# ./start_demo.sh root 2-node/ --runtostep run --policy autoadd
sshuser=root
demodir=2-node/
Removing contents of "/tmp/etce/lxcroot" directory.
Bringing up bridge: emanenode0
Traceback (most recent call last):
 File "/usr/lib/python3.6/site-packages/etce/lxcmanager.py", line 58, in startlxcs
 dryrun=dryrun)
 File "/usr/lib/python3.6/site-packages/etce/lxcmanager.py", line 144, in start
 enablemulticastsnooping=True)
 File "/usr/lib/python3.6/site-packages/etce/platform.py", line 113, in bridgeup
 self._impl.bridgeup(bridgename, addifs, enablemulticastsnooping)
 File "/usr/lib/python3.6/site-packages/etce/linux/platformimpl.py", line 143, in bridgeup
 with open('/sys/devices/virtual/net/%s/bridge/multicast_snooping' % bridgename, 'w') as sf:
PermissionError: [Errno 13] Permission denied: '/sys/devices/virtual/net/emanenode0/bridge/multicast_snooping'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
 File "/bin/etce-lxc", line 109, in <module>
 main()
 File "/bin/etce-lxc", line 102, in main
 args.func(args)
 File "/usr/lib/python3.6/site-packages/etce/lxcfieldmanager.py", line 72, in startfield
 args.dryrun)
 File "/usr/lib/python3.6/site-packages/etce/lxcmanager.py", line 60, in startlxcs
 raise LXCError(e.message)
AttributeError: 'PermissionError' object has no attribute 'message'
Waiting for LXCs ...

TestCollection:
 2-node

Ignoring kill argument "both" used in conjunction with runtostep. Using "before" instead.

Running the same Docker container on Windows without WSL2 integration works fine. Any idea about why the /sys/devices/virtual/net/emanenode0/bridge/multicast_snooping creation is denied in one flavor vs. the other?

Cheers.

[eschreiber-alink]

I don't have ready access to a WSL2 environment. Try troubleshooting the issue outside of ETCE by running the bridge creation commands manually. As root:

# bring up the bridge
root@host:~# ip link add emanenode0 type bridge
root@host:~# ip link set emanenode0 up

# check the current snooping value
root@host:~# cat /sys/devices/virtual/net/emanenode0/bridge/multicast_snooping
1

# set to 0
root@host:~# echo 0 > /sys/devices/virtual/net/emanenode0/bridge/multicast_snooping 
root@host:~# cat /sys/devices/virtual/net/emanenode0/bridge/multicast_snooping 
0

[vinsworldcom]

Eric,

Thanks, I realized my issue didn't include the additional commands I had captured. The 'multicast_snooping` "object" is not created for the interface on the WSL2 linux kernel:

user@hostname:/mnt/c/Users/user$ sudo ip link add emanenode0 type bridge
user@hostname:/mnt/c/Users/user$ sudo ip link set emanenode0 up
user@hostname:/mnt/c/Users/user$ cat /sys/devices/virtual/net/emanenode0/bridge/multicast_snooping
cat: /sys/devices/virtual/net/emanenode0/bridge/multicast_snooping: No such file or directory
user@hostname:/mnt/c/Users/user$ ls /sys/devices/virtual/net/emanenode0/bridge/
ageing_time group_fwd_mask priority topology_change_detected
bridge_id hello_time root_id topology_change_timer
default_pvid hello_timer root_path_cost vlan_filtering
flush max_age root_port vlan_protocol
forward_delay nf_call_arptables stp_state vlan_stats_enabled
gc_timer nf_call_ip6tables tcn_timer
group_addr nf_call_iptables topology_change
user@hostname:/mnt/c/Users/user$ uname -a
Linux hostname 4.19.128-microsoft-standard #1 SMP Tue Jun 23 12:58:10 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

If the 'multicast_snooping` "object" is not created, I wonder what is preventing that? The WSL2 Linux in use is Ubuntu 20.04:

PS USER C:\Users\user> wsl -l -v
 NAME STATE VERSION
* Ubuntu-20.04 Running 2
 docker-desktop-data Running 2
 docker-desktop Running 2

I changed "True" to "False" for enablemulticastsnooping in:

"/usr/lib/python3.6/site-packages/etce/lxcmanager.py":

 142 self._platform.bridgeup(bridge.devicename,
 143 bridge.addifs,
 144 enablemulticastsnooping=False)

And all seems to work fine now since the "False" skips setting the multicast_snooping "object" later in "/usr/lib/python3.6/site-packages/etce/linux/platformimpl.py". There doesn't seem to be an etce-lxc option for multicast_snooping on or off.

Cheers.

[vinsworldcom]

Since there seems to be no way to configure whether you want multicast_snooping on or off; rather it's set to True in "/usr/lib/python3.6/site-packages/etce/lxcmanager.py" before calling "/usr/lib/python3.6/site-packages/etce/linux/platformimpl.py", maybe a simple check in "/usr/lib/python3.6/site-packages/etce/linux/platformimpl.py" to see if it exists before operating on it:

diff --git a/etce/linux/platformimpl.py b/etce/linux/platformimpl.py
index 8614e41..6ba8cd4 100644
--- a/etce/linux/platformimpl.py
+++ b/etce/linux/platformimpl.py
@@ -140,8 +140,9 @@ class PlatformImpl(etce.platformimpl.PlatformImpl):
 self.runcommand('ip link set %s up' % interface)

 if enablemulticastsnooping:
- with open('/sys/devices/virtual/net/%s/bridge/multicast_snooping' % bridgename, 'w') as sf:
- sf.write('0')
+ if os.path.exists('/sys/devices/virtual/net/%s/bridge/multicast_snooping' % bridgename):
+ with open('/sys/devices/virtual/net/%s/bridge/multicast_snooping' % bridgename, 'w') as sf:
+ sf.write('0')


 def bridgedown(self, bridgename, addifs):

Cheers.

[eschreiber-alink]

Added this check to develop branch. Thanks for your contribution.