0717df0452
Alternative to using a sudoers file to limit which commands can be run as root in Nova. This one makes use of command filters defined in Nova code itself, which can be customized to deeply inspect command arguments before allowing a command to be executed. This change puts the infrastructure in place, together with command filters that replicate the level of filtering provided by a sudoers file (no deep argument inspection yet). An example of an advanced filter (RegExpFilter) is also provided. This new root wrapper is not active by default (root_helper still defaults to "sudo"). Implements blueprint nova-rootwrap. Change-Id: I7ad723b55e9446758876f21b4fbb09374a910425
81 lines
2.7 KiB
Python
Executable File
81 lines
2.7 KiB
Python
Executable File
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (c) 2011 Openstack, LLC.
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import os
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import re
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class CommandFilter(object):
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"""Command filter only checking that the 1st argument matches exec_path"""
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def __init__(self, exec_path, run_as, *args):
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self.exec_path = exec_path
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self.run_as = run_as
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self.args = args
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def match(self, userargs):
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"""Only check that the first argument (command) matches exec_path"""
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if (os.path.basename(self.exec_path) == userargs[0]):
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return True
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return False
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def get_command(self, userargs):
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"""Returns command to execute (with sudo -u if run_as != root)."""
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if (self.run_as != 'root'):
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# Used to run commands at lesser privileges
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return ['sudo', '-u', self.run_as, self.exec_path] + userargs[1:]
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return [self.exec_path] + userargs[1:]
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class RegExpFilter(CommandFilter):
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"""Command filter doing regexp matching for every argument"""
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def match(self, userargs):
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# Early skip if command or number of args don't match
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if (len(self.args) != len(userargs)):
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# DENY: argument numbers don't match
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return False
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# Compare each arg (anchoring pattern explicitly at end of string)
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for (pattern, arg) in zip(self.args, userargs):
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try:
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if not re.match(pattern + '$', arg):
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break
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except re.error:
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# DENY: Badly-formed filter
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return False
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else:
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# ALLOW: All arguments matched
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return True
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# DENY: Some arguments did not match
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return False
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class DnsmasqFilter(CommandFilter):
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"""Specific filter for the dnsmasq call (which includes env)"""
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def match(self, userargs):
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if (userargs[0].startswith("FLAGFILE=") and
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userargs[1].startswith("NETWORK_ID=") and
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userargs[2] == "dnsmasq"):
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return True
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return False
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def get_command(self, userargs):
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return userargs[0:2] + [self.exec_path] + userargs[3:]
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