openstack/neutron
Code Issues Proposed changes

Make ARP protection commands compatible with "ebtables-nft"

Browse Source 
"nftables" compatible binary, "ebtables-nft", is not 100% compatible
with the legacy API, as reported in LP#1922892.

This patch fixes the following issues when using "ebtables-nft" (while
keeping compatibility with legacy binary):
- When a new chain is created, a default DROP rule is added at the end
  of the chain (append). This will prevent the error code 4 when the
  chain is listed.
- The chain rules are added at the begining of the chain (insert),
  before the default DROP rule. This will prioritize the port rules.
- The MAC rules are cleaned before the new ones are added. That will
  prevent the deletion of any new needed rule, now added after the
  deletion.
- The "ebtables" command will retry on error code 4. This is the
  error returned when the chains are listed and no rule is present
  in a new created chain (reporeted in LP#1922892).

This code is backwards compatible, that means it works with the legacy
"ebtables" binary; this is currently installed in the Neutron CI [1].
In order to test with the new binary, "ebtables-nft", two new CI jobs
are added to the periodic queue [2].

[1]1ad9ca56b0/roles/legacy_ebtables/tasks/main.yaml
[2]https://review.opendev.org/c/openstack/neutron/+/785144

Closes-Bug: #1922892
Related-Bug: #1508155

Change-Id: I9463b000f6f63e65aaf91d60b30f6c92c01e3baf
This commit is contained in:
Rodolfo Alonso Hernandez 2021-04-07 13:16:21 +00:00 committed by Rodolfo Alonso
parent cca2b8de2c
commit 0a931391d8
2 changed files with 36 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
neutron/plugins/ml2/drivers/linuxbridge/agent/arp_protect.py
View File

@ -73,12 +73,6 @@ def delete_arp_spoofing_protection(vifs):
_delete_arp_spoofing_protection(vifs, current_rules, table='nat',
chain='PREROUTING')
# TODO(haleyb) this can go away in "R" cycle, it's here to cleanup
# old chains in the filter table
current_rules = ebtables(['-L'], table='filter').splitlines()
_delete_arp_spoofing_protection(vifs, current_rules, table='filter',
chain='FORWARD')
def _delete_arp_spoofing_protection(vifs, current_rules, table, chain):
# delete the jump rule and then delete the whole chain
@ -92,10 +86,11 @@ def _delete_arp_spoofing_protection(vifs, current_rules, table, chain):
chain=chain)
def _delete_unreferenced_arp_protection(current_vifs, table, chain):
@lockutils.synchronized('ebtables')
def delete_unreferenced_arp_protection(current_vifs):
# deletes all jump rules and chains that aren't in current_vifs but match
# the spoof prefix
current_rules = ebtables(['-L'], table=table).splitlines()
current_rules = ebtables(['-L'], table='nat').splitlines()
to_delete = []
for line in current_rules:
# we're looking to find and turn the following:
@ -107,19 +102,8 @@ def _delete_unreferenced_arp_protection(current_vifs, table, chain):
to_delete.append(devname)
LOG.info("Clearing orphaned ARP spoofing entries for devices %s",
to_delete)
_delete_arp_spoofing_protection(to_delete, current_rules, table=table,
chain=chain)
@lockutils.synchronized('ebtables')
def delete_unreferenced_arp_protection(current_vifs):
_delete_unreferenced_arp_protection(current_vifs,
table='nat', chain='PREROUTING')
# TODO(haleyb) this can go away in "R" cycle, it's here to cleanup
# old chains in the filter table
_delete_unreferenced_arp_protection(current_vifs,
table='filter', chain='FORWARD')
_delete_arp_spoofing_protection(to_delete, current_rules, table='nat',
chain='PREROUTING')
@lockutils.synchronized('ebtables')
@ -133,12 +117,17 @@ def _install_arp_spoofing_protection(vif, addresses, current_rules):
vif_chain = chain_name(vif)
if not chain_exists(vif_chain, current_rules):
ebtables(['-N', vif_chain, '-P', 'DROP'])
# flush the chain to clear previous accepts. this will cause dropped ARP
# packets until the allows are installed, but that's better than leaked
# spoofed packets and ARP can handle losses.
ebtables(['-F', vif_chain])
# Append a default DROP rule at the end of the chain. This will
# avoid "ebtables-nft" error when listing the chain.
ebtables(['-A', vif_chain, '-j', 'DROP'])
else:
# Flush the chain to clear previous accepts. This will cause dropped
# ARP packets until the allows are installed, but that's better than
# leaked spoofed packets and ARP can handle losses.
ebtables(['-F', vif_chain])
ebtables(['-A', vif_chain, '-j', 'DROP'])
for addr in sorted(addresses):
ebtables(['-A', vif_chain, '-p', 'ARP', '--arp-ip-src', addr,
ebtables(['-I', vif_chain, '-p', 'ARP', '--arp-ip-src', addr,
'-j', 'ACCEPT'])
# check if jump rule already exists, if not, install it
if not vif_jump_present(vif, current_rules):
@ -178,17 +167,22 @@ def _install_mac_spoofing_protection(vif, port_details, current_rules):
# mac filter chain for each vif which has a default deny
if not chain_exists(vif_chain, current_rules):
ebtables(['-N', vif_chain, '-P', 'DROP'])
# Append a default DROP rule at the end of the chain. This will
# avoid "ebtables-nft" error when listing the chain.
ebtables(['-A', vif_chain, '-j', 'DROP'])
# check if jump rule already exists, if not, install it
if not _mac_vif_jump_present(vif, current_rules):
ebtables(['-A', 'PREROUTING', '-i', vif, '-j', vif_chain])
ebtables(['-I', 'PREROUTING', '-i', vif, '-j', vif_chain])
_delete_vif_mac_rules(vif, current_rules)
# we can't just feed all allowed macs at once because we can exceed
# the maximum argument size. limit to 500 per rule.
for chunk in (mac_addresses[i:i + 500]
for i in range(0, len(mac_addresses), 500)):
new_rule = ['-A', vif_chain, '-i', vif,
new_rule = ['-I', vif_chain, '-i', vif,
'--among-src', ','.join(sorted(chunk)), '-j', 'RETURN']
ebtables(new_rule)
_delete_vif_mac_rules(vif, current_rules)
def _mac_vif_jump_present(vif, current_rules):
@ -227,7 +221,7 @@ NAMESPACE = None
@tenacity.retry(
wait=tenacity.wait_exponential(multiplier=0.02),
retry=tenacity.retry_if_exception(lambda e: e.returncode == 255),
retry=tenacity.retry_if_exception(lambda e: e.returncode in [255, 4]),
reraise=True
)
def ebtables(comm, table='nat'):

51
neutron/tests/unit/plugins/ml2/drivers/linuxbridge/agent/test_arp_protect.py
View File

@ -75,13 +75,19 @@ class TestLinuxBridgeARPSpoofing(base.BaseTestCase):
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.ANY,
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-A',
'neutronMAC-%s' % vif, '-j', 'DROP'],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.ANY,
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-I',
'PREROUTING', '-i', vif, '-j', mac_chain],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-A',
mock.ANY,
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-I',
mac_chain, '-i', vif,
'--among-src', '%s' % ','.join(sorted(mac_addresses)),
'-j', 'RETURN'],
@ -89,21 +95,20 @@ class TestLinuxBridgeARPSpoofing(base.BaseTestCase):
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.ANY,
mock.ANY,
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-N',
spoof_chain, '-P', 'DROP'],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-F',
spoof_chain],
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-A',
spoof_chain, '-j', 'DROP'],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
privsep_exec=True)
]
for addr in sorted(ip_addresses):
expected.extend([
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-A',
mock.call(['ebtables', '-t', 'nat', '--concurrent', '-I',
spoof_chain, '-p', 'ARP',
'--arp-ip-src', addr, '-j', 'ACCEPT'],
check_exit_code=True, extra_ok_codes=None,
@ -167,38 +172,6 @@ class TestLinuxBridgeARPSpoofing(base.BaseTestCase):
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.call(['ebtables', '-t', 'filter', '--concurrent', '-L'],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.ANY,
mock.call(['ebtables', '-t', 'filter', '--concurrent', '-D',
'FORWARD', '-i', VIF, '-j', spoof_chain,
'-p', 'ARP'],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.call(['ebtables', '-t', 'filter', '--concurrent', '-F',
spoof_chain],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.call(['ebtables', '-t', 'filter', '--concurrent', '-X',
spoof_chain],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.ANY,
mock.call(['ebtables', '-t', 'filter', '--concurrent', '-F',
mac_chain],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
mock.call(['ebtables', '-t', 'filter', '--concurrent', '-X',
mac_chain],
check_exit_code=True, extra_ok_codes=None,
log_fail_as_error=True, run_as_root=True,
privsep_exec=True),
]
arp_protect.delete_arp_spoofing_protection([VIF])