Unable to delete filter of clsact/ingress

[jschwinger233]

Reproduce steps:

First let's create the clsact qdisc and a bpf filter.

ipr.tc("add", "clsact", 1) # dev lo
ipr.tc(
    "add-filter",
    "bpf",
    1, # dev lo
    ":1",
    fd=func.fd,
    name=func.name,
    parent='ffff:fff2',
    classid=1,
    direct_action=True,
)

Then we can check the status:

$ tc filter show dev lo parent ffff:fff2
filter protocol all pref 49152 bpf chain 0 
filter protocol all pref 49152 bpf chain 0 handle 0x1 flowid :1 tc_pass direct-action not_in_hw id 329 tag 15858a412926acbb

However the consequent del-filter won't work:

ipr.tc("del-filter", "bpf", iface_idx, ':1', parent='ffff:fff2')

will raise error

Traceback (most recent call last):
  File "basic01-xdp-pass/tc_loader.bcc.py", line 45, in <module>
    ipr.tc("del-filter", "bpf", iface_idx, ':0', parent=parent)
  File "/usr/lib/python3/dist-packages/pyroute2/iproute/linux.py", line 1614, in tc
    return tuple(self.nlm_request(msg, msg_type=command, msg_flags=flags))
  File "/usr/lib/python3/dist-packages/pyroute2/netlink/nlsocket.py", line 376, in nlm_request
    return tuple(self._genlm_request(*argv, **kwarg))
  File "/usr/lib/python3/dist-packages/pyroute2/netlink/nlsocket.py", line 867, in nlm_request
    for msg in self.get(msg_seq=msg_seq,
  File "/usr/lib/python3/dist-packages/pyroute2/netlink/nlsocket.py", line 379, in get
    return tuple(self._genlm_get(*argv, **kwarg))
  File "/usr/lib/python3/dist-packages/pyroute2/netlink/nlsocket.py", line 704, in get
    raise msg['header']['error']
pyroute2.netlink.exceptions.NetlinkError: (2, 'No such file or directory')

I guess it's caused by tcm_info in the request of RTM_DELTFILTER, somehow the parameter is set to 0x300 instead of 0, but I don't know how to make the correction.

[jschwinger233]

Maybe this issue is interrelated?

[svinota]

Thanks, working on it!

[svinota]

The issue caused by incorrect tcm_info encoding.

To mitigate the error, you can use right now:

ipr.tc("del-filter", "bpf", iface_idx, ':1', protocol=0, prio=0xc000, parent='ffff:fff2')

Corresponding code:

pyroute2/pyroute2.core/pr2modules/netlink/rtnl/tcmsg/sched_bpf.py

Lines 23 to 26 in 4e73961

	def fix_msg(msg, kwarg):
	msg['info'] = htons(kwarg.pop('protocol', ETH_P_ALL) & 0xFFFF) | (
	(kwarg.pop('prio', 0) << 16) & 0xFFFF0000
	)

Tomorrow I'm to fix this. And #745 as well.

[svinota]

Looks like fixed:

pyroute2/tests/test_linux/test_tc/test_bpf.py

Lines 80 to 107 in 878bbc9

	def test_filter_delete(context, bpf):
	context.ipr.tc('add', kind='clsact', index=context.default_interface.index)
	context.ipr.tc(
	'add-filter',
	kind='bpf',
	index=context.default_interface.index,
	fd=bpf,
	name='my_func',
	parent='ffff:fff2',
	classid=1,
	direct_action=True,
	)
	filters = context.ipr.get_filters(
	index=context.default_interface.index, parent='ffff:fff2'
	)
	# len == 2: handles 0 and 1
	assert len(filters) == 2
	context.ipr.tc(
	'del-filter',
	kind='bpf',
	index=context.default_interface.index,
	parent='ffff:fff2',
	info=filters[0]['info'],
	)
	filters = context.ipr.get_filters(
	index=context.default_interface.index, parent='ffff:fff2'
	)
	assert len(filters) == 0

The next release which will include this fix is to be tagged tomorrow