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executable file 287 lines (254 sloc) 13.158 kb
#!/usr/bin/python
#
# Copyright (c) 2011 Citrix Systems, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation; version 2.1 only. with the special
# exception on linking described in file LICENSE.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
import fcntl
import os
import os.path
import string
import subprocess
import sys
import syslog
import time
command_name = sys.argv[0]
short_command_name = os.path.basename(command_name)
ebtables = "/sbin/ebtables"
ebtables_lock_path = "/var/lock/ebtables.lock"
vsctl = "/usr/bin/ovs-vsctl"
ofctl = "/usr/bin/ovs-ofctl"
ip = "/sbin/ip"
xenstore_read_cmd = "/usr/bin/xenstore-read"
host_network_config = "/etc/xensource/network.conf"
def get_host_network_mode():
f = open(host_network_config, "r")
try:
return f.readline().strip()
finally:
f.close()
def send_to_syslog(msg):
pid = os.getpid()
syslog.syslog("%s[%d] - %s" %(command_name, pid, msg))
def doexec(args):
"""Execute a subprocess, then return its return code, stdout and stderr"""
send_to_syslog(args)
proc = subprocess.Popen(args,stdin=None,stdout=subprocess.PIPE,stderr=subprocess.PIPE,close_fds=True)
rc = proc.wait()
stdout = proc.stdout
stderr = proc.stderr
return (rc, stdout, stderr)
def xenstore_read(path):
(rc, stdout, stderr) = doexec([xenstore_read_cmd, path])
return stdout.readline().strip()
def get_words(value, separator):
if string.strip(value) == "":
return []
else:
return string.split(value, separator)
def get_locking_config(domid, devid):
mac = xenstore_read("/local/domain/0/backend/vif/%s/%s/mac" % (domid, devid))
private_path = "/xapi/%s/private/vif/%s" % (domid, devid)
locking_mode = xenstore_read("/".join([private_path, "locking-mode"]))
ipv4_allowed = xenstore_read("/".join([private_path, "ipv4-allowed"]))
ipv6_allowed = xenstore_read("/".join([private_path, "ipv6-allowed"]))
send_to_syslog("Got locking config: MAC=%s; locking_mode=%s; ipv4_allowed=%s; ipv6_allowed=%s"
% (mac, locking_mode, ipv4_allowed, ipv6_allowed))
return {
"mac": mac,
"locking_mode": locking_mode,
"ipv4_allowed": get_words(ipv4_allowed, ","),
"ipv6_allowed": get_words(ipv6_allowed, ",")
}
def ip_link_set(device, direction):
doexec([ip, "link", "set", device, direction])
###############################################################################
# Creation of ebtables rules in the case of bridge.
###############################################################################
def get_chain_name(vif_name):
return ("FORWARD_%s" % vif_name)
def do_chain_action(executable, action, chain_name, args=[]):
return doexec([executable, action, chain_name] + args)
def chain_exists(executable, chain_name):
rc, _, _ = do_chain_action(executable, "-L", chain_name)
return (rc == 0)
def clear_bridge_rules(vif_name):
vif_chain = get_chain_name(vif_name)
if chain_exists(ebtables, vif_chain):
# Stop forwarding to this VIF's chain.
do_chain_action(ebtables, "-D", "FORWARD", ["-i", vif_name, "-j", vif_chain])
do_chain_action(ebtables, "-D", "FORWARD", ["-o", vif_name, "-j", vif_chain])
# Flush and delete the VIF's chain.
do_chain_action(ebtables, "-F", vif_chain)
do_chain_action(ebtables, "-X", vif_chain)
def create_bridge_rules(vif_name, config):
vif_chain = get_chain_name(vif_name)
# Forward all traffic on this VIF to a new chain, with default policy DROP.
do_chain_action(ebtables, "-N", vif_chain)
do_chain_action(ebtables, "-A", "FORWARD", ["-i", vif_name, "-j", vif_chain])
do_chain_action(ebtables, "-A", "FORWARD", ["-o", vif_name, "-j", vif_chain])
do_chain_action(ebtables, "-P", vif_chain, ["DROP"])
# We now need to create rules to allow valid traffic.
mac = config["mac"]
# We only fully support IPv4 multitenancy with bridge.
# We allow all IPv6 traffic if any IPv6 addresses are associated with the VIF.
ipv4_allowed = config["ipv4_allowed"]
ipv6_allowed = config["ipv6_allowed"]
# Accept all traffic going to the VM.
do_chain_action(ebtables, "-A", vif_chain, ["-o", vif_name, "-j", "ACCEPT"])
# Drop everything not coming from the correct MAC.
do_chain_action(ebtables, "-A", vif_chain, ["-s", "!", mac, "-i", vif_name, "-j", "DROP"])
# Accept DHCP.
do_chain_action(ebtables, "-A", vif_chain, ["-p", "IPv4", "-i", vif_name, "--ip-protocol", "UDP", "--ip-dport", "67", "-j", "ACCEPT"])
for ipv4 in ipv4_allowed:
# Accept ARP travelling from known IP addresses, also filtering ARP replies by MAC.
do_chain_action(ebtables, "-A", vif_chain, ["-p", "ARP", "-i", vif_name, "--arp-opcode", "Request", "--arp-ip-src", ipv4, "-j", "ACCEPT"])
do_chain_action(ebtables, "-A", vif_chain, ["-p", "ARP", "-i", vif_name, "--arp-opcode", "Reply", "--arp-ip-src", ipv4, "--arp-mac-src", mac, "-j", "ACCEPT"])
# Accept IP travelling from known IP addresses.
do_chain_action(ebtables, "-A", vif_chain, ["-p", "IPv4", "-i", vif_name, "--ip-src", ipv4, "-j", "ACCEPT"])
if ipv6_allowed != []:
# Accept all IPv6 traffic.
do_chain_action(ebtables, "-A", vif_chain, ["-p", "IPv6", "-i", vif_name, "-j", "ACCEPT"])
def acquire_lock(path):
lock_file = open(path, 'w')
while True:
send_to_syslog("attempting to acquire lock %s" % path)
try:
fcntl.lockf(lock_file, fcntl.LOCK_EX | fcntl.LOCK_NB)
send_to_syslog("acquired lock %s" % path)
return lock_file
except IOError, e:
send_to_syslog("failed to acquire lock %s because '%s' - waiting 1 second" % (path, e))
time.sleep(1)
def handle_bridge(vif_type, domid, devid, action):
if (action == "clear") or (action == "filter"):
# ebtables fails if called concurrently, so acquire a lock before starting to call it.
ebtables_lock_file = acquire_lock(ebtables_lock_path)
vif_name = "%s%s.%s" % (vif_type, domid, devid)
ip_link_set(vif_name, "down")
clear_bridge_rules(vif_name)
if action == "filter":
config = get_locking_config(domid, devid)
locking_mode = config["locking_mode"]
if locking_mode == "locked":
create_bridge_rules(vif_name, config)
if locking_mode in ["locked", "unlocked"]:
ip_link_set(vif_name, "up")
if action == "clear":
ip_link_set(vif_name, "up")
###############################################################################
# Creation of openflow rules in the case of openvswitch.
###############################################################################
def get_vswitch_port(vif_name):
(rc, stdout, stderr) = doexec([vsctl, "get", "interface", vif_name, "ofport"])
return stdout.readline().strip()
def clear_vswitch_rules(bridge_name, port):
doexec([ofctl, "del-flows", bridge_name, "in_port=%s" % port])
def add_flow(bridge_name, args):
doexec([ofctl, "add-flow", bridge_name, args])
def create_vswitch_rules(bridge_name, port, config):
mac = config["mac"]
ipv4_allowed = config["ipv4_allowed"]
ipv6_allowed = config["ipv6_allowed"]
# Allow DHCP traffic (outgoing UDP on port 67).
add_flow(bridge_name, "in_port=%s,priority=8000,dl_type=0x0800,nw_proto=0x11,"
"tp_dst=67,dl_src=%s,idle_timeout=0,action=normal" % (port, mac))
# Filter ARP requests.
add_flow(bridge_name, "in_port=%s,priority=7000,dl_type=0x0806,dl_src=%s,arp_sha=%s,"
"nw_src=0.0.0.0,idle_timeout=0,action=normal" % (port, mac, mac))
for ipv4 in ipv4_allowed:
# Filter ARP responses.
add_flow(bridge_name, "in_port=%s,priority=7000,dl_type=0x0806,dl_src=%s,arp_sha=%s,"
"nw_src=%s,idle_timeout=0,action=normal" % (port, mac, mac, ipv4))
# Allow traffic from specified ipv4 addresses.
add_flow(bridge_name, "in_port=%s,priority=6000,dl_type=0x0800,nw_src=%s,"
"dl_src=%s,idle_timeout=0,action=normal" % (port, ipv4, mac))
for ipv6 in ipv6_allowed:
# Neighbour solicitation.
add_flow(bridge_name, "in_port=%s,priority=8000,dl_src=%s,icmp6,ipv6_src=%s,"
"icmp_type=135,nd_sll=%s,idle_timeout=0,action=normal" % (port, mac, ipv6, mac))
# Neighbour advertisement.
add_flow(bridge_name, "in_port=%s,priority=8000,dl_src=%s,icmp6,ipv6_src=%s,"
"icmp_type=136,nd_target=%s,idle_timeout=0,action=normal" % (port, mac, ipv6, ipv6))
# Allow traffic from specified ipv6 addresses.
add_flow(bridge_name, "in_port=%s,priority=5000,dl_src=%s,ipv6_src=%s,icmp6,action=normal" % (port, mac, ipv6))
add_flow(bridge_name, "in_port=%s,priority=5000,dl_src=%s,ipv6_src=%s,tcp6,action=normal" % (port, mac, ipv6))
add_flow(bridge_name, "in_port=%s,priority=5000,dl_src=%s,ipv6_src=%s,udp6,action=normal" % (port, mac, ipv6))
# Drop all other neighbour discovery.
add_flow(bridge_name, "in_port=%s,priority=7000,icmp6,icmp_type=135,action=drop" % port)
add_flow(bridge_name, "in_port=%s,priority=7000,icmp6,icmp_type=136,action=drop" % port)
# Drop other specific ICMPv6 types.
# Router advertisement.
add_flow(bridge_name, "in_port=%s,priority=6000,icmp6,icmp_type=134,action=drop" % port)
# Redirect gateway.
add_flow(bridge_name, "in_port=%s,priority=6000,icmp6,icmp_type=137,action=drop" % port)
# Mobile prefix solicitation.
add_flow(bridge_name, "in_port=%s,priority=6000,icmp6,icmp_type=146,action=drop" % port)
# Mobile prefix advertisement.
add_flow(bridge_name, "in_port=%s,priority=6000,icmp6,icmp_type=147,action=drop" % port)
# Multicast router advertisement.
add_flow(bridge_name, "in_port=%s,priority=6000,icmp6,icmp_type=151,action=drop" % port)
# Multicast router solicitation.
add_flow(bridge_name, "in_port=%s,priority=6000,icmp6,icmp_type=152,action=drop" % port)
# Multicast router termination.
add_flow(bridge_name, "in_port=%s,priority=6000,icmp6,icmp_type=153,action=drop" % port)
# Drop everything else.
add_flow(bridge_name, "in_port=%s,priority=4000,idle_timeout=0,action=drop" % port)
def get_bridge_name_vswitch(vif_name):
'''return bridge vif belong to'''
(rc, stdout, stderr) = doexec([vsctl, "iface-to-br", vif_name ])
temp_bridge_name = stdout.readline().strip()
'''get bridge parent, in case we were given a fake bridge device'''
'''will return same name if it is already a real bridge'''
(rc, stdout, stderr) = doexec([vsctl, "br-to-parent", temp_bridge_name ])
return stdout.readline().strip()
def handle_vswitch(vif_type, domid, devid, action):
if (action == "clear") or (action == "filter"):
vif_name = "%s%s.%s" % (vif_type, domid, devid)
bridge_name = get_bridge_name_vswitch(vif_name)
ip_link_set(vif_name, "down")
port = get_vswitch_port(vif_name)
clear_vswitch_rules(bridge_name, port)
if action == "filter":
config = get_locking_config(domid, devid)
locking_mode = config["locking_mode"]
if locking_mode == "locked":
create_vswitch_rules(bridge_name, port, config)
if locking_mode in ["locked", "unlocked"]:
ip_link_set(vif_name, "up")
if action == "clear":
ip_link_set(vif_name, "up")
###############################################################################
# Executable entry point.
###############################################################################
def main(vif_type, domid, devid, network_mode, action):
if network_mode == "bridge":
handle_bridge(vif_type, domid, devid, action)
elif network_mode == "openvswitch":
handle_vswitch(vif_type, domid, devid, action)
def usage():
print "Usage:"
print "%s vif_type domid devid action" % short_command_name
print ""
print "vif_type: [vif|tap]"
print " The type of the vif for which rules will be created."
print "action: [clear|filter]"
print " Specifies whether to create filtering rules for the vif, or to clear all rules associated with the vif."
if __name__ == "__main__":
if len(sys.argv) != 5:
usage()
sys.exit(1)
else:
network_mode = get_host_network_mode ()
vif_type, domid, devid, action = sys.argv[1:5]
send_to_syslog("Called with vif_type=%s, domid=%s, devid=%s, network_mode=%s, action=%s" %
(vif_type, domid, devid, network_mode, action))
main(vif_type, domid, devid, network_mode, action)
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