Mini Shell
# -*- coding: utf-8 -*-
# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc
# 2010-2018 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT
#
import os
import re
import subprocess
CAGEFS_MP_FILENAME = "/etc/cagefs/cagefs.mp"
CAGEFSCTL_TOOL = "/usr/sbin/cagefsctl"
class CagefsMpConflict(Exception):
def __init__(self, new_item, existing_item):
self._msg = (
"Conflict in adding '%s' to %s because of pre-existing "
"alternative specification: '%s'"
% (new_item, CAGEFS_MP_FILENAME, existing_item)
)
def __str__(self):
return self._msg
class CagefsMpItem:
PREFIX_LIST = b"@!%"
_PREFIX_MOUNT_RW = b""
_PREFIX_MOUNT_RO = b"!"
def __init__(self, arg):
"""Constructor
:param arg: Is either path to add to cagefs.mp or a raw line is read
from cagefs.mp
:param prefix: The same as adding prefix '!' to arg before passing it
to ctor"""
if arg[:1] == b"#": # is a comment? then init as dummy
self._path_spec = None
elif arg.strip() == b"": # init as dummy for empty lines
self._path_spec = None
else:
self._path_spec = arg
def mode(self, mode):
"""Specify mode as in fluent constructor"""
if self.prefix() == b"@" and mode is not None:
self._path_spec = b"%s,%03o" % (self._path_spec, mode)
return self
def __str__(self):
return os.fsdecode(self._path_spec)
@staticmethod
def _add_slash(path):
if path == b"":
return b"/"
if path[-1] != b"/"[0]:
return path + b"/"
return path
def pre_exist_in(self, another):
adopted = CagefsMpItem._adopt(another)
# overkill: just to keep strictly to comparing NULL objects principle
if self.is_dummy() or adopted.is_dummy():
return False
this_path = CagefsMpItem._add_slash(self.path())
test_preexist_in_path = CagefsMpItem._add_slash(adopted.path())
return this_path.startswith(test_preexist_in_path)
def is_compatible_by_prefix_with(self, existing):
adopted = CagefsMpItem._adopt(existing)
# overkill: just to keep strictly to comparing NULL objects principle
if self.is_dummy() or adopted.is_dummy():
return False
if self.prefix() == adopted.prefix():
return True
prefix_compatibility_map = {
CagefsMpItem._PREFIX_MOUNT_RW: [CagefsMpItem._PREFIX_MOUNT_RO]
}
null_options = []
return self.prefix() in prefix_compatibility_map.get(
adopted.prefix(), null_options
)
def is_dummy(self):
return self._path_spec is None
@staticmethod
def _adopt(x):
if isinstance(x, CagefsMpItem):
return x
else:
return CagefsMpItem(x)
@staticmethod
def _cut_off_mode(path_spec):
"""Cut off mode from path spec like @/var/run/screen,777
Only one comma per path spec is allowed ;-)"""
return path_spec.split(b",")[0]
@staticmethod
def _cut_off_prefix(path_spec):
return path_spec.lstrip(CagefsMpItem.PREFIX_LIST)
def path(self):
return CagefsMpItem._cut_off_prefix(
CagefsMpItem._cut_off_mode(self._path_spec)
)
def prefix(self):
if self._path_spec != self.path():
return self._path_spec[0:1]
else:
return b""
def spec(self):
return self._path_spec
def is_cagefs_present():
return os.path.exists(CAGEFSCTL_TOOL)
def _mk_mount_dir_setup_perm(path, mode=0o755, owner_id=None, group_id=None):
# -1 means 'unchanged'
if group_id is None:
group_id = -1
if owner_id is None:
owner_id = -1
if not os.path.isdir(path):
os.mkdir(path)
if mode is not None:
os.chmod(path, mode)
os.chown(path, owner_id, group_id)
def setup_mount_dir_cagefs(
path,
added_by,
mode=0o755,
owner_id=None,
group_id=None,
prefix=b"",
remount_cagefs=True,
):
"""
Add mount point to /etc/cagefs/cagefs.mp
:param path: Directory path to be added in cagefs.mp and mounted
from within setup_mount_dir_cagefs().
If this directory does not exist, then it is created.
:param added_by: package or component, mount dir relates to, or whatever
will stay in cagefs.mp with "# added by..." comment
:param mode: If is not None: Regardless of whether directory exists or not
prior this call, it's permissions will be set to mode.
:param owner_id: Regardless of whether directory exists or not prior this
call, it's owner id will be set to.
If None, the owner won't be changed.
:param group_id: Regardless of whether directory exists or not prior this
call, it's group id will be set to.
If None, the group won't be changed.
:param prefix: Mount point prefix. Default is mount as RW.
Pass '!' to add read-only mount point.
Refer CageFS section at http://docs.cloudlinux.com/
for more options.
:param remount_cagefs: If True, cagefs skeleton will be automatically
remounted to apply changes.
:returns: None
Propagates native EnvironmentError if no CageFS installed or something
else goes wrong.
Raises CagefsMpConflict if path is already specified in cagefs.mp,
but in a way which is opposite to mount_as_readonly param.
"""
_mk_mount_dir_setup_perm(path, mode, owner_id, group_id)
# Create cagefs.mp if absent. It will be merged when cagefsctl --init.
if not os.path.exists(CAGEFS_MP_FILENAME):
subprocess.call([CAGEFSCTL_TOOL, "--create-mp"])
subprocess.call([CAGEFSCTL_TOOL, "--check-mp"])
# ^^
# Hereafter we will not care if there was
# 'no newline at the end of file'
cagefs_mp = open(CAGEFS_MP_FILENAME, "rb+")
try:
new_item = CagefsMpItem(prefix + path).mode(mode)
trim_nl_iter = (file_line.rstrip() for file_line in cagefs_mp)
pre_exist_option = [
x for x in trim_nl_iter if new_item.pre_exist_in(x)
]
if not pre_exist_option:
cagefs_mp.seek(0, 2) # 2: seek to the end of file
# no newline is allowed
added_by = added_by.replace("\n", " ")
cagefs_mp.write(
b"# next line is added by " + added_by.encode("utf-8") + b"\n"
)
cagefs_mp.write(new_item.spec() + b"\n")
cagefs_mp.close()
if remount_cagefs:
subprocess.call([CAGEFSCTL_TOOL, "--remount-all"])
elif not new_item.is_compatible_by_prefix_with(pre_exist_option[-1]):
raise CagefsMpConflict(new_item, pre_exist_option[-1])
finally:
cagefs_mp.close()
def _get_cagefs_mp_lines():
with open(CAGEFS_MP_FILENAME, "rb") as f:
return f.readlines()
def _write_cagefs_mp_lines(lines):
with open(CAGEFS_MP_FILENAME, "wb") as f:
return f.writelines(lines)
def remove_mount_dir_cagefs(path, remount_cagefs=True):
"""
Remove mount points matching given path from cagefs.mp file
:param str path: Path that should be removed from file.
:param bool remount_cagefs: Remount cagefs skeleton or not
:return: Nothing
"""
lines = _get_cagefs_mp_lines()
r = re.compile(
rb"^[%s]?%s(,\d+)?$" % (CagefsMpItem.PREFIX_LIST, re.escape(path))
)
lines_with_excluded_path = (line for line in lines if not r.match(line))
_write_cagefs_mp_lines(lines_with_excluded_path)
if remount_cagefs:
subprocess.call([CAGEFSCTL_TOOL, "--remount-all"])