Viewing file: 
backend.py (22.94 KB) -rw-r--r--Select action/file-type:
(
+) |
(
+) |
(
+) |
Code (
+) |
Session (
+) |
(
+) |
SDB (
+) |
(
+) |
(
+) |
(
+) |
(
+) |
(
+) |
#
# backend.py: interface for backends
#
# Copyright 2008-2010 Canonical Ltd.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3,
# as published by the Free Software Foundation.
#
# 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
import errno
import os
import re
import stat
from stat import *
import sys
import ufw.util
from ufw.util import warn, debug
from ufw.common import UFWError, config_dir, iptables_dir, UFWRule
import ufw.applications
class UFWBackend:
'''Interface for backends'''
def __init__(self, name, d, extra_files={}):
self.defaults = {}
self.name = name
self.dryrun = d
self.rules = []
self.rules6 = []
self.files = {'defaults': os.path.join(config_dir, 'default/ufw'),
'conf': os.path.join(config_dir, 'ufw/ufw.conf'),
'apps': os.path.join(config_dir, 'ufw/applications.d') }
self.files.update(extra_files)
self.loglevels = {'off': 0,
'low': 100,
'medium': 200,
'high': 300,
'full': 400 }
self.do_checks = True
try:
self._do_checks()
self._get_defaults()
self._read_rules()
except Exception:
raise
self.profiles = ufw.applications.get_profiles(self.files['apps'])
self.iptables = os.path.join(iptables_dir, "iptables")
self.iptables_restore = os.path.join(iptables_dir, "iptables-restore")
self.ip6tables = os.path.join(iptables_dir, "ip6tables")
self.ip6tables_restore = os.path.join(iptables_dir, \
"ip6tables-restore")
self.iptables_version = ufw.util.get_iptables_version(self.iptables)
def _is_enabled(self):
if self.defaults.has_key('enabled') and \
self.defaults['enabled'] == 'yes':
return True
return False
def use_ipv6(self):
if self.defaults.has_key('ipv6') and \
self.defaults['ipv6'] == 'yes' and \
os.path.exists("/proc/sys/net/ipv6"):
return True
return False
def _do_checks(self):
'''Perform basic security checks:
is setuid or setgid (for non-Linux systems)
checks that script is owned by root
checks that every component in absolute path are owned by root
warn if script is group writable
warn if part of script path is group writable
Doing this at the beginning causes a race condition with later
operations that don't do these checks. However, if the user running
this script is root, then need to be root to exploit the race
condition (and you are hosed anyway...)
'''
if not self.do_checks:
err_msg = _("Checks disabled")
warn(err_msg)
return True
# Not needed on Linux, but who knows the places we will go...
if os.getuid() != os.geteuid():
err_msg = _("ERROR: this script should not be SUID")
raise UFWError(err_msg)
if os.getgid() != os.getegid():
err_msg = _("ERROR: this script should not be SGID")
raise UFWError(err_msg)
uid = os.getuid()
if uid != 0:
err_msg = _("You need to be root to run this script")
raise UFWError(err_msg)
# Use these so we only warn once
warned_world_write = {}
warned_group_write = {}
warned_owner = {}
profiles = []
if not os.path.isdir(self.files['apps']):
warn_msg = _("'%s' does not exist") % (self.files['apps'])
warn(warn_msg)
else:
pat = re.compile(r'^\.')
for profile in os.listdir(self.files['apps']):
if not pat.search(profile):
profiles.append(os.path.join(self.files['apps'], profile))
for path in self.files.values() + [ os.path.abspath(sys.argv[0]) ] + \
profiles:
while True:
debug("Checking " + path)
if path == self.files['apps'] and \
not os.path.isdir(self.files['apps']):
break
try:
statinfo = os.stat(path)
mode = statinfo[ST_MODE]
except OSError, e:
err_msg = _("Couldn't stat '%s'") % (path)
raise UFWError(err_msg)
except Exception:
raise
if statinfo.st_uid != 0 and not warned_owner.has_key(path):
warn_msg = _("uid is %(uid)s but '%(path)s' is owned by " \
"%(st_uid)s") % ({'uid': str(uid), \
'path': path, \
'st_uid': str(statinfo.st_uid)})
warn(warn_msg)
warned_owner[path] = True
if mode & S_IWOTH and not warned_world_write.has_key(path):
warn_msg = _("%s is world writable!") % (path)
warn(warn_msg)
warned_world_write[path] = True
if mode & S_IWGRP and not warned_group_write.has_key(path):
warn_msg = _("%s is group writable!") % (path)
warn(warn_msg)
warned_group_write[path] = True
if path == "/":
break
path = os.path.dirname(path)
if not path:
raise OSError(errno.ENOENT, "Could not find '%s'" % (path))
for f in self.files:
if f != 'apps' and not os.path.isfile(self.files[f]):
err_msg = _("'%(f)s' file '%(name)s' does not exist") % \
({'f': f, 'name': self.files[f]})
raise UFWError(err_msg)
def _get_defaults(self):
'''Get all settings from defaults file'''
self.defaults = {}
for f in [self.files['defaults'], self.files['conf']]:
try:
orig = ufw.util.open_file_read(f)
except Exception:
err_msg = _("Couldn't open '%s' for reading") % (f)
raise UFWError(err_msg)
pat = re.compile(r'^\w+="?\w+"?')
for line in orig:
if pat.search(line):
tmp = re.split(r'=', line.strip())
self.defaults[tmp[0].lower()] = tmp[1].lower().strip('"\'')
orig.close()
# do some default policy sanity checking
policies = ['accept', 'accept_no_track', 'drop', 'reject']
for c in [ 'input', 'output', 'forward' ]:
if not self.defaults.has_key('default_%s_policy' % (c)):
err_msg = _("Missing policy for '%s'" % (c))
raise UFWError(err_msg)
p = self.defaults['default_%s_policy' % (c)]
if p not in policies or \
(p == 'accept_no_track' and c == 'forward'):
err_msg = _("Invalid policy '%(policy)s' for '%(chain)s'" % \
({'policy': p, 'chain': c}))
raise UFWError(err_msg)
def set_default(self, f, opt, value):
'''Sets option in defaults file'''
if not re.match(r'^[\w_]+$', opt):
err_msg = _("Invalid option")
raise UFWError(err_msg)
# Perform this here so we can present a nice error to the user rather
# than a traceback
if not os.access(f, os.W_OK):
err_msg = _("'%s' is not writable" % (f))
raise UFWError(err_msg)
try:
fns = ufw.util.open_files(f)
except Exception:
raise
fd = fns['tmp']
found = False
pat = re.compile(r'^' + opt + '=')
for line in fns['orig']:
if pat.search(line):
ufw.util.write_to_file(fd, opt + "=" + value + "\n")
found = True
else:
ufw.util.write_to_file(fd, line)
# Add the entry if not found
if not found:
ufw.util.write_to_file(fd, opt + "=" + value + "\n")
try:
ufw.util.close_files(fns)
except Exception:
raise
# Now that the files are written out, update value in memory
self.defaults[opt.lower()] = value.lower().strip('"\'')
def set_default_application_policy(self, policy):
'''Sets default application policy of firewall'''
if not self.dryrun:
if policy == "allow":
try:
self.set_default(self.files['defaults'], \
"DEFAULT_APPLICATION_POLICY", \
"\"ACCEPT\"")
except Exception:
raise
elif policy == "deny":
try:
self.set_default(self.files['defaults'], \
"DEFAULT_APPLICATION_POLICY", \
"\"DROP\"")
except Exception:
raise
elif policy == "reject":
try:
self.set_default(self.files['defaults'], \
"DEFAULT_APPLICATION_POLICY", \
"\"REJECT\"")
except Exception:
raise
elif policy == "skip":
try:
self.set_default(self.files['defaults'], \
"DEFAULT_APPLICATION_POLICY", \
"\"SKIP\"")
except Exception:
raise
else:
err_msg = _("Unsupported policy '%s'") % (policy)
raise UFWError(err_msg)
rstr = _("Default application policy changed to '%s'") % (policy)
return rstr
def get_app_rules_from_template(self, template):
'''Return a list of UFWRules based on the template rule'''
rules = []
profile_names = self.profiles.keys()
if template.dport in profile_names and template.sport in profile_names:
dports = ufw.applications.get_ports(self.profiles[template.dport])
sports = ufw.applications.get_ports(self.profiles[template.sport])
for i in dports:
tmp = template.dup_rule()
tmp.dapp = ""
tmp.set_port("any", "src")
try:
(port, proto) = ufw.util.parse_port_proto(i)
tmp.set_protocol(proto)
tmp.set_port(port, "dst")
except Exception:
raise
tmp.dapp = template.dapp
if template.dport == template.sport:
# Just use the same ports as dst for src when they are the
# same to avoid duplicate rules
tmp.sapp = ""
try:
(port, proto) = ufw.util.parse_port_proto(i)
tmp.set_protocol(proto)
tmp.set_port(port, "src")
except Exception:
raise
tmp.sapp = template.sapp
rules.append(tmp)
else:
for j in sports:
rule = tmp.dup_rule()
rule.sapp = ""
try:
(port, proto) = ufw.util.parse_port_proto(j)
rule.set_protocol(proto)
rule.set_port(port, "src")
except Exception:
raise
if rule.protocol == "any":
rule.set_protocol(tmp.protocol)
rule.sapp = template.sapp
rules.append(rule)
elif template.sport in profile_names:
for p in ufw.applications.get_ports(self.profiles[template.sport]):
rule = template.dup_rule()
rule.sapp = ""
try:
(port, proto) = ufw.util.parse_port_proto(p)
rule.set_protocol(proto)
rule.set_port(port, "src")
except Exception:
raise
rule.sapp = template.sapp
rules.append(rule)
elif template.dport in profile_names:
for p in ufw.applications.get_ports(self.profiles[template.dport]):
rule = template.dup_rule()
rule.dapp = ""
try:
(port, proto) = ufw.util.parse_port_proto(p)
rule.set_protocol(proto)
rule.set_port(port, "dst")
except Exception:
raise
rule.dapp = template.dapp
rules.append(rule)
if len(rules) < 1:
err_msg = _("No rules found for application profile")
raise UFWError(err_msg)
return rules
def update_app_rule(self, profile):
'''Update rule for profile in place. Returns result string and bool
on whether or not the profile is used in the current ruleset.
'''
updated_rules = []
updated_rules6 = []
last_tuple = ""
rstr = ""
updated_profile = False
# Remember, self.rules is from user[6].rules, and not the running
# firewall.
for r in self.rules + self.rules6:
if r.dapp == profile or r.sapp == profile:
# We assume that the rules are in app rule order. Specifically,
# if app rule has multiple rules, they are one after the other.
# If the rule ordering changes, the below will have to change.
tupl = r.get_app_tuple()
if tupl == last_tuple:
# Skip the rule if seen this tuple already (ie, it is part
# of a known tuple).
continue
else:
# Have a new tuple, so find and insert new app rules here
template = r.dup_rule()
template.set_protocol("any")
if template.dapp != "":
template.set_port(template.dapp, "dst")
if template.sapp != "":
template.set_port(template.sapp, "src")
try:
new_app_rules = self.get_app_rules_from_template(\
template)
except Exception:
raise
for new_r in new_app_rules:
new_r.normalize()
if new_r.v6:
updated_rules6.append(new_r)
else:
updated_rules.append(new_r)
last_tuple = tupl
updated_profile = True
else:
if r.v6:
updated_rules6.append(r)
else:
updated_rules.append(r)
if updated_profile:
self.rules = updated_rules
self.rules6 = updated_rules6
rstr += _("Rules updated for profile '%s'") % (profile)
try:
self._write_rules(False) # ipv4
self._write_rules(True) # ipv6
except Exception:
err_msg = _("Couldn't update application rules")
raise UFWError(err_msg)
return (rstr, updated_profile)
def find_application_name(self, str):
'''Find the application profile name for str'''
if self.profiles.has_key(str):
return str
match = ""
matches = 0
for n in self.profiles.keys():
if n.lower() == str.lower():
match = n
matches += 1
debug_msg = "'%d' matches for '%s'" % (matches, str)
debug(debug_msg)
if matches == 1:
return match
elif matches > 1:
err_msg = _("Found multiple matches for '%s'. Please use exact profile name") % (str)
err_msg = _("Could not find a profile matching '%s'") % (str)
raise UFWError(err_msg)
def find_other_position(self, position, v6):
'''Return the absolute position in the other list of the rule with the
user position of the given list. For example, find_other_position(4,
True) will return the absolute position of the rule in the ipv4 list
matching the user specified '4' rule in the ipv6 list.
'''
# Invalid search (v6 rule with too low position)
if v6 and position > len(self.rules6):
raise ValueError()
# Invalid search (v4 rule with too high position)
if not v6 and position > len(self.rules):
raise ValueError()
if position < 1:
raise ValueError()
rules = []
if v6:
rules = self.rules6
else:
rules = self.rules
# self.rules[6] is a list of tuples. Some application rules have
# multiple tuples but the user specifies by ufw rule, not application
# tuple, so we need to find how many tuples there are leading up to
# the specified position, which we can then use as an offset for
# getting the proper match_rule.
app_rules = {}
tuple_offset = 0
for i, r in enumerate(rules):
if i >= position:
break
tupl = ""
if r.dapp != "" or r.sapp != "":
tupl = r.get_app_tuple()
if app_rules.has_key(tupl):
tuple_offset += 1
else:
app_rules[tupl] = True
rules = []
if v6:
rules = self.rules
match_rule = self.rules6[position - 1 + tuple_offset].dup_rule()
match_rule.set_v6(False)
else:
rules = self.rules6
match_rule = self.rules[position - 1 + tuple_offset].dup_rule()
match_rule.set_v6(True)
count = 1
for r in rules:
if UFWRule.match(r, match_rule) == 0:
return count
count += 1
return 0
def get_loglevel(self):
'''Gets current log level of firewall'''
level = 0
rstr = _("Logging: ")
if not self.defaults.has_key('loglevel') or \
self.defaults['loglevel'] not in self.loglevels.keys():
level = -1
rstr += _("unknown")
else:
level = self.loglevels[self.defaults['loglevel']]
if level == 0:
rstr += "off"
else:
rstr += "on (%s)" % (self.defaults['loglevel'])
return (level, rstr)
def set_loglevel(self, level):
'''Sets log level of firewall'''
if level not in self.loglevels.keys() + ['on']:
err_msg = _("Invalid log level '%s'") % (level)
raise UFWError(err_msg)
new_level = level
if level == "on":
if not self.defaults.has_key('loglevel') or \
self.defaults['loglevel'] == "off":
new_level = "low"
else:
new_level = self.defaults['loglevel']
try:
self.set_default(self.files['conf'], "LOGLEVEL", new_level)
self.update_logging(new_level)
except Exception:
raise
if new_level == "off":
return _("Logging disabled")
else:
return _("Logging enabled")
def get_rules(self):
'''Return list of all rules'''
return self.rules + self.rules6
def get_rules_count(self, v6):
'''Return number of ufw rules (not iptables rules)'''
rules = []
if v6:
rules = self.rules6
else:
rules = self.rules
count = 0
app_rules = {}
for r in rules:
tupl = ""
if r.dapp != "" or r.sapp != "":
tupl = r.get_app_tuple()
if app_rules.has_key(tupl):
debug("Skipping found tuple '%s'" % (tupl))
continue
else:
app_rules[tupl] = True
count += 1
return count
def get_rule_by_number(self, n):
'''Return rule specified by number seen via "status numbered"'''
rules = self.get_rules()
count = 1
app_rules = {}
for r in rules:
tupl = ""
if r.dapp != "" or r.sapp != "":
tupl = r.get_app_tuple()
if app_rules.has_key(tupl):
debug("Skipping found tuple '%s'" % (tupl))
continue
else:
app_rules[tupl] = True
if count == int(n):
return r
count += 1
return None
def get_matching(self, rule):
'''See if there is a matching rule in the existing ruleset. Note this
does not group rules by tuples.'''
matched = []
count = 0
for r in self.get_rules():
count += 1
ret = rule.fuzzy_dst_match(r)
if ret < 1:
matched.append(count)
return matched
# API overrides
def get_default_policy(self):
raise UFWError("UFWBackend.get_default_policy: need to override")
def set_default_policy(self, policy, direction):
raise UFWError("UFWBackend.set_default_policy: need to override")
def get_running_raw(self, set):
raise UFWError("UFWBackend.get_running_raw: need to override")
def get_status(self, verbose, show_count):
raise UFWError("UFWBackend.get_status: need to override")
def get_status_as_list(self):
raise UFWError("UFWBackend.get_status_as_list: need to override")
def set_rule(self, rule, allow_reload):
raise UFWError("UFWBackend.set_rule: need to override")
def start_firewall(self):
raise UFWError("UFWBackend.start_firewall: need to override")
def stop_firewall(self):
raise UFWError("UFWBackend.stop_firewall: need to override")
def get_app_rules_from_system(self, template, v6):
raise UFWError("UFWBackend.get_app_rules_from_system: need to " + \
"override")
def update_logging(self, level):
raise UFWError("UFWBackend.update_logging: need to override")
def reset(self):
raise UFWError("UFWBackend.reset: need to override")
