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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright (c) 2011 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import os
import re
class CommandFilter(object):
"""Command filter only checking that the 1st argument matches exec_path."""
def __init__(self, exec_path, run_as, *args):
self.name = ''
self.exec_path = exec_path
self.run_as = run_as
self.args = args
self.real_exec = None
def get_exec(self, exec_dirs=[]):
"""Returns existing executable, or empty string if none found."""
if self.real_exec is not None:
return self.real_exec
self.real_exec = ""
if os.path.isabs(self.exec_path):
if os.access(self.exec_path, os.X_OK):
self.real_exec = self.exec_path
else:
for binary_path in exec_dirs:
expanded_path = os.path.join(binary_path, self.exec_path)
if os.access(expanded_path, os.X_OK):
self.real_exec = expanded_path
break
return self.real_exec
def match(self, userargs):
"""Only check that the first argument (command) matches exec_path."""
return os.path.basename(self.exec_path) == userargs[0]
def get_command(self, userargs, exec_dirs=[]):
"""Returns command to execute (with sudo -u if run_as != root)."""
to_exec = self.get_exec(exec_dirs=exec_dirs) or self.exec_path
if (self.run_as != 'root'):
# Used to run commands at lesser privileges
return ['sudo', '-u', self.run_as, to_exec] + userargs[1:]
return [to_exec] + userargs[1:]
def get_environment(self, userargs):
"""Returns specific environment to set, None if none."""
return None
class RegExpFilter(CommandFilter):
"""Command filter doing regexp matching for every argument."""
def match(self, userargs):
# Early skip if command or number of args don't match
if (len(self.args) != len(userargs)):
# DENY: argument numbers don't match
return False
# Compare each arg (anchoring pattern explicitly at end of string)
for (pattern, arg) in zip(self.args, userargs):
try:
if not re.match(pattern + '$', arg):
break
except re.error:
# DENY: Badly-formed filter
return False
else:
# ALLOW: All arguments matched
return True
# DENY: Some arguments did not match
return False
class PathFilter(CommandFilter):
"""Command filter checking that path arguments are within given dirs
One can specify the following constraints for command arguments:
1) pass - pass an argument as is to the resulting command
2) some_str - check if an argument is equal to the given string
3) abs path - check if a path argument is within the given base dir
A typical rootwrapper filter entry looks like this:
# cmdname: filter name, raw command, user, arg_i_constraint [, ...]
chown: PathFilter, /bin/chown, root, nova, /var/lib/images
"""
def match(self, userargs):
command, arguments = userargs[0], userargs[1:]
equal_args_num = len(self.args) == len(arguments)
exec_is_valid = super(PathFilter, self).match(userargs)
args_equal_or_pass = all(
arg == 'pass' or arg == value
for arg, value in zip(self.args, arguments)
if not os.path.isabs(arg) # arguments not specifying abs paths
)
paths_are_within_base_dirs = all(
os.path.commonprefix([arg, os.path.realpath(value)]) == arg
for arg, value in zip(self.args, arguments)
if os.path.isabs(arg) # arguments specifying abs paths
)
return (equal_args_num and
exec_is_valid and
args_equal_or_pass and
paths_are_within_base_dirs)
def get_command(self, userargs, exec_dirs=[]):
command, arguments = userargs[0], userargs[1:]
# convert path values to canonical ones; copy other args as is
args = [os.path.realpath(value) if os.path.isabs(arg) else value
for arg, value in zip(self.args, arguments)]
return super(PathFilter, self).get_command([command] + args,
exec_dirs)
class DnsmasqFilter(CommandFilter):
"""Specific filter for the dnsmasq call (which includes env)."""
CONFIG_FILE_ARG = 'CONFIG_FILE'
def match(self, userargs):
if (userargs[0] == 'env' and
userargs[1].startswith(self.CONFIG_FILE_ARG) and
userargs[2].startswith('NETWORK_ID=') and
userargs[3] == 'dnsmasq'):
return True
return False
def get_command(self, userargs, exec_dirs=[]):
to_exec = self.get_exec(exec_dirs=exec_dirs) or self.exec_path
dnsmasq_pos = userargs.index('dnsmasq')
return [to_exec] + userargs[dnsmasq_pos + 1:]
def get_environment(self, userargs):
env = os.environ.copy()
env[self.CONFIG_FILE_ARG] = userargs[1].split('=')[-1]
env['NETWORK_ID'] = userargs[2].split('=')[-1]
return env
class DeprecatedDnsmasqFilter(DnsmasqFilter):
"""Variant of dnsmasq filter to support old-style FLAGFILE."""
CONFIG_FILE_ARG = 'FLAGFILE'
class KillFilter(CommandFilter):
"""Specific filter for the kill calls.
1st argument is the user to run /bin/kill under
2nd argument is the location of the affected executable
if the argument is not absolute, it is checked against $PATH
Subsequent arguments list the accepted signals (if any)
This filter relies on /proc to accurately determine affected
executable, so it will only work on procfs-capable systems (not OSX).
"""
def __init__(self, *args):
super(KillFilter, self).__init__("/bin/kill", *args)
def match(self, userargs):
if userargs[0] != "kill":
return False
args = list(userargs)
if len(args) == 3:
# A specific signal is requested
signal = args.pop(1)
if signal not in self.args[1:]:
# Requested signal not in accepted list
return False
else:
if len(args) != 2:
# Incorrect number of arguments
return False
if len(self.args) > 1:
# No signal requested, but filter requires specific signal
return False
try:
command = os.readlink("/proc/%d/exe" % int(args[1]))
except (ValueError, OSError):
# Incorrect PID
return False
# NOTE(yufang521247): /proc/PID/exe may have '\0' on the
# end, because python doen't stop at '\0' when read the
# target path.
command = command.partition('\0')[0]
# NOTE(dprince): /proc/PID/exe may have ' (deleted)' on
# the end if an executable is updated or deleted
if command.endswith(" (deleted)"):
command = command[:-len(" (deleted)")]
kill_command = self.args[0]
if os.path.isabs(kill_command):
return kill_command == command
return (os.path.isabs(command) and
kill_command == os.path.basename(command) and
os.path.dirname(command) in os.environ['PATH'].split(':'))
class ReadFileFilter(CommandFilter):
"""Specific filter for the utils.read_file_as_root call."""
def __init__(self, file_path, *args):
self.file_path = file_path
super(ReadFileFilter, self).__init__("/bin/cat", "root", *args)
def match(self, userargs):
if userargs[0] != 'cat':
return False
if userargs[1] != self.file_path:
return False
if len(userargs) != 2:
return False
return True
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