151 lines
5.4 KiB
Python
151 lines
5.4 KiB
Python
# Copyright 2018 The Chromium OS Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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import logging
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import os
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import subprocess
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import shutil
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import tempfile
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from autotest_lib.client.bin import test, utils
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from autotest_lib.client.common_lib import error
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MOUNT_PATH=tempfile.mkdtemp()
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class security_NosymfollowMountOption(test.test):
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"""
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Mount filesystems with the "nosymfollow" option and ensure symlink
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traversal is blocked.
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"""
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version = 1
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def __init__(self, *args, **kwargs):
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# TODO(mortonm): add a function to utils to do this kernel version
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# check and raise NAError.
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version = utils.get_kernel_version()
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if version == "3.8.11":
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raise error.TestNAError('Test is n/a for kernels older than 3.10')
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super(security_NosymfollowMountOption,
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self).__init__(*args, **kwargs)
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self._failure = False
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def cleanup(self):
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"""
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Clean up test environment.
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"""
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super(security_NosymfollowMountOption, self).cleanup()
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shutil.rmtree(MOUNT_PATH)
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def _fail(self, msg):
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"""
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Log failure message and record failure.
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@param msg: String to log.
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"""
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logging.error(msg)
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self._failure = True
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def umount(self):
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"""
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Unmount file system at MOUNT_PATH location.
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"""
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try:
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subprocess.check_output(["/bin/umount", MOUNT_PATH])
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except subprocess.CalledProcessError, e:
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self._fail("umount call failed")
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def mount_and_test_with_string(self, mount_options, restrict_symlinks):
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"""
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Mount file system with given options, check it was mounted with
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correct options, and make sure symlink traversal restriction works as
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expected.
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@param mount_options: Mount options string.
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@param restrict_symlinks: True if mount options should cause symlinks
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to be restricted, False otherwise.
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"""
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try:
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subprocess.check_output(["/bin/mount",
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"-n",
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"-t",
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"tmpfs",
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"-o",
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mount_options,
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"tmpfs",
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MOUNT_PATH])
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except subprocess.CalledProcessError:
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self._fail("mount call failed")
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return
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try:
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ps = subprocess.Popen(('mount'), stdout=subprocess.PIPE)
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output = subprocess.check_output(('grep',MOUNT_PATH),
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stdin=ps.stdout)
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ps.wait()
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for arg in mount_options.split(','):
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if arg == "nosymfollow":
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continue
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else:
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if output.find(arg) == -1:
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self._fail("filesystem missing '%s' arg" % arg)
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return
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try:
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open(MOUNT_PATH + "/file", "w+")
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os.symlink(MOUNT_PATH + "/file", MOUNT_PATH + "/link")
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except IOError:
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self._fail("creating/linking files failed")
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return
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traversal_restricted = False
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try:
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open(MOUNT_PATH + "/link", "r")
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except IOError:
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traversal_restricted = True
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if restrict_symlinks:
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if not traversal_restricted:
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self._fail("symlink traversal was not restricted")
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return
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else:
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if traversal_restricted:
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self._fail("symlink traversal was restricted")
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finally:
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self.umount()
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def run_once(self, test_selinux_interaction):
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"""
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Runs the test, mounting filesystems and checking symlink traversal
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behavior.
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"""
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self.mount_and_test_with_string("nosymfollow", True)
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self.mount_and_test_with_string("nodev,noexec,nosuid,nosymfollow", True)
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self.mount_and_test_with_string("nodev,noexec,nosuid", False)
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if test_selinux_interaction:
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if not os.path.exists('/etc/selinux'):
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raise error.TestNAError('Test is n/a if selinux is not enabled')
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self.mount_and_test_with_string("nosymfollow,"
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"context=u:object_r:tmpfs:s0,"
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"fscontext=u:object_r:tmpfs:s0",
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True)
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self.mount_and_test_with_string("context=u:object_r:tmpfs:s0,"
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"nosymfollow,"
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"fscontext=u:object_r:tmpfs:s0",
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True)
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self.mount_and_test_with_string("context=u:object_r:tmpfs:s0,"
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"fscontext=u:object_r:tmpfs:s0,"
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"nosymfollow",
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True)
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# Make the test fail if any unexpected behaviour got detected. Note
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# that the error log output that will be included in the failure
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# message mentions the failed location to aid debugging.
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if self._failure:
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raise error.TestFail('Unexpected mount behavior')
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