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"""Compat module to handle files security on Windows and Linux"""
from __future__ import absolute_import
from contextlib import contextmanager
import errno
import os # pylint: disable=os-module-forbidden
import stat
import sys
from typing import Any
from typing import Dict
from typing import Generator
from typing import List
from typing import Optional
try:
import ntsecuritycon
import pywintypes
import win32api
import win32con
import win32file
import win32security
import winerror
except ImportError:
POSIX_MODE = True
else:
POSIX_MODE = False
# Windows umask implementation, since Windows does not have a concept of umask by default.
# We choose 022 as initial value since it is the default one on most Linux distributions, and
# it is a decent choice to not have write permissions for group owner and everybody by default.
# We use a class here to avoid needing to define a global variable, and the potential mistakes
# that could happen with this kind of pattern.
class _WindowsUmask:
"""Store the current umask to apply on Windows"""
def __init__(self) -> None:
self.mask = 0o022
_WINDOWS_UMASK = _WindowsUmask()
def chmod(file_path: str, mode: int) -> None:
"""
Apply a POSIX mode on given file_path:
- for Linux, the POSIX mode will be directly applied using chmod,
- for Windows, the POSIX mode will be translated into a Windows DACL that make sense for
Certbot context, and applied to the file using kernel calls.
The definition of the Windows DACL that correspond to a POSIX mode, in the context of Certbot,
is explained at https://github.com/certbot/certbot/issues/6356 and is implemented by the
method `_generate_windows_flags()`.
:param str file_path: Path of the file
:param int mode: POSIX mode to apply
"""
if POSIX_MODE:
os.chmod(file_path, mode)
else:
_apply_win_mode(file_path, mode)
def umask(mask: int) -> int:
"""
Set the current numeric umask and return the previous umask. On Linux, the built-in umask
method is used. On Windows, our Certbot-side implementation is used.
:param int mask: The user file-creation mode mask to apply.
:rtype: int
:return: The previous umask value.
"""
if POSIX_MODE:
return os.umask(mask)
previous_umask = _WINDOWS_UMASK.mask
_WINDOWS_UMASK.mask = mask
return previous_umask
@contextmanager
def temp_umask(mask: int) -> Generator[None, None, None]:
"""
Apply a umask temporarily, meant to be used in a `with` block. Uses the Certbot
implementation of umask.
:param int mask: The user file-creation mode mask to apply temporarily
"""
old_umask: Optional[int] = None
try:
old_umask = umask(mask)
yield None
finally:
if old_umask is not None:
umask(old_umask)
# One could ask why there is no copy_ownership() function, or even a reimplementation
# of os.chown() that would modify the ownership of file without touching the mode itself.
# This is because on Windows, it would require recalculating the existing DACL against
# the new owner, since the DACL is composed of ACEs that targets a specific user, not dynamically
# the current owner of a file. This action would be necessary to keep consistency between
# the POSIX mode applied to the file and the current owner of this file.
# Since copying and editing arbitrary DACL is very difficult, and since we actually know
# the mode to apply at the time the owner of a file should change, it is easier to just
# change the owner, then reapply the known mode, as copy_ownership_and_apply_mode() does.
def copy_ownership_and_apply_mode(src: str, dst: str, mode: int,
copy_user: bool, copy_group: bool) -> None:
"""
Copy ownership (user and optionally group on Linux) from the source to the
destination, then apply given mode in compatible way for Linux and Windows.
This replaces the os.chown command.
:param str src: Path of the source file
:param str dst: Path of the destination file
:param int mode: Permission mode to apply on the destination file
:param bool copy_user: Copy user if `True`
:param bool copy_group: Copy group if `True` on Linux (has no effect on Windows)
"""
if POSIX_MODE:
stats = os.stat(src)
user_id = stats.st_uid if copy_user else -1
group_id = stats.st_gid if copy_group else -1
# On Windows, os.chown does not exist. This is checked through POSIX_MODE value,
# but MyPy/PyLint does not know it and raises an error here on Windows.
# We disable specifically the check to fix the issue.
os.chown(dst, user_id, group_id)
elif copy_user:
# There is no group handling in Windows
_copy_win_ownership(src, dst)
chmod(dst, mode)
# Quite similar to copy_ownership_and_apply_mode, but this time the DACL is copied from
# the source file on Windows. The DACL stays consistent with the dynamic rights of the
# equivalent POSIX mode, because ownership and mode are copied altogether on the destination
# file, so no recomputing of the DACL against the new owner is needed, as it would be
# for a copy_ownership alone method.
def copy_ownership_and_mode(src: str, dst: str,
copy_user: bool = True, copy_group: bool = True) -> None:
"""
Copy ownership (user and optionally group on Linux) and mode/DACL
from the source to the destination.
:param str src: Path of the source file
:param str dst: Path of the destination file
:param bool copy_user: Copy user if `True`
:param bool copy_group: Copy group if `True` on Linux (has no effect on Windows)
"""
if POSIX_MODE:
# On Linux, we just delegate to chown and chmod.
stats = os.stat(src)
user_id = stats.st_uid if copy_user else -1
group_id = stats.st_gid if copy_group else -1
os.chown(dst, user_id, group_id)
chmod(dst, stats.st_mode)
else:
if copy_user:
# There is no group handling in Windows
_copy_win_ownership(src, dst)
_copy_win_mode(src, dst)
def check_mode(file_path: str, mode: int) -> bool:
"""
Check if the given mode matches the permissions of the given file.
On Linux, will make a direct comparison, on Windows, mode will be compared against
the security model.
:param str file_path: Path of the file
:param int mode: POSIX mode to test
:rtype: bool
:return: True if the POSIX mode matches the file permissions
"""
if POSIX_MODE:
return stat.S_IMODE(os.stat(file_path).st_mode) == mode
return _check_win_mode(file_path, mode)
def check_owner(file_path: str) -> bool:
"""
Check if given file is owned by current user.
:param str file_path: File path to check
:rtype: bool
:return: True if given file is owned by current user, False otherwise.
"""
if POSIX_MODE:
return os.stat(file_path).st_uid == os.getuid()
# Get owner sid of the file
security = win32security.GetFileSecurity(file_path, win32security.OWNER_SECURITY_INFORMATION)
user = security.GetSecurityDescriptorOwner()
# Compare sids
return _get_current_user() == user
def check_permissions(file_path: str, mode: int) -> bool:
"""
Check if given file has the given mode and is owned by current user.
:param str file_path: File path to check
:param int mode: POSIX mode to check
:rtype: bool
:return: True if file has correct mode and owner, False otherwise.
"""
return check_owner(file_path) and check_mode(file_path, mode)
def open(file_path: str, flags: int, mode: int = 0o777) -> int: # pylint: disable=redefined-builtin
"""
Wrapper of original os.open function, that will ensure on Windows that given mode
is correctly applied.
:param str file_path: The file path to open
:param int flags: Flags to apply on file while opened
:param int mode: POSIX mode to apply on file when opened,
Python defaults will be applied if ``None``
:returns: the file descriptor to the opened file
:rtype: int
:raise: OSError(errno.EEXIST) if the file already exists and os.O_CREAT & os.O_EXCL are set,
OSError(errno.EACCES) on Windows if the file already exists and is a directory, and
os.O_CREAT is set.
"""
if POSIX_MODE:
# On Linux, invoke os.open directly.
return os.open(file_path, flags, mode)
# Windows: handle creation of the file atomically with proper permissions.
if flags & os.O_CREAT:
# If os.O_EXCL is set, we will use the "CREATE_NEW", that will raise an exception if
# file exists, matching the API contract of this bit flag. Otherwise, we use
# "CREATE_ALWAYS" that will always create the file whether it exists or not.
disposition = win32con.CREATE_NEW if flags & os.O_EXCL else win32con.CREATE_ALWAYS
attributes = win32security.SECURITY_ATTRIBUTES()
security = attributes.SECURITY_DESCRIPTOR
user = _get_current_user()
dacl = _generate_dacl(user, mode, _WINDOWS_UMASK.mask)
# We set second parameter to 0 (`False`) to say that this security descriptor is
# NOT constructed from a default mechanism, but is explicitly set by the user.
# See https://docs.microsoft.com/en-us/windows/desktop/api/securitybaseapi/nf-securitybaseapi-setsecuritydescriptorowner # pylint: disable=line-too-long
security.SetSecurityDescriptorOwner(user, 0)
# We set first parameter to 1 (`True`) to say that this security descriptor contains
# a DACL. Otherwise second and third parameters are ignored.
# We set third parameter to 0 (`False`) to say that this security descriptor is
# NOT constructed from a default mechanism, but is explicitly set by the user.
# See https://docs.microsoft.com/en-us/windows/desktop/api/securitybaseapi/nf-securitybaseapi-setsecuritydescriptordacl # pylint: disable=line-too-long
security.SetSecurityDescriptorDacl(1, dacl, 0)
handle = None
try:
handle = win32file.CreateFile(file_path, win32file.GENERIC_READ,
win32file.FILE_SHARE_READ & win32file.FILE_SHARE_WRITE,
attributes, disposition, 0, None)
except pywintypes.error as err:
# Handle native windows errors into python errors to be consistent with the API
# of os.open in the situation of a file already existing or locked.
if err.winerror == winerror.ERROR_FILE_EXISTS:
raise OSError(errno.EEXIST, err.strerror)
if err.winerror == winerror.ERROR_SHARING_VIOLATION:
raise OSError(errno.EACCES, err.strerror)
raise err
finally:
if handle:
handle.Close()
# At this point, the file that did not exist has been created with proper permissions,
# so os.O_CREAT and os.O_EXCL are not needed anymore. We remove them from the flags to
# avoid a FileExists exception before calling os.open.
return os.open(file_path, flags ^ os.O_CREAT ^ os.O_EXCL)
# Windows: general case, we call os.open, let exceptions be thrown, then chmod if all is fine.
fd = os.open(file_path, flags)
chmod(file_path, mode)
return fd
def makedirs(file_path: str, mode: int = 0o777) -> None:
"""
Rewrite of original os.makedirs function, that will ensure on Windows that given mode
is correctly applied.
:param str file_path: The file path to open
:param int mode: POSIX mode to apply on leaf directory when created, Python defaults
will be applied if ``None``
"""
current_umask = umask(0)
try:
# Since Python 3.7, os.makedirs does not set the given mode to the intermediate
# directories that could be created in the process. To keep things safe and consistent
# on all Python versions, we set the umask accordingly to have all directories
# (intermediate and leaf) created with the given mode.
umask(current_umask | 0o777 ^ mode)
if POSIX_MODE:
return os.makedirs(file_path, mode)
orig_mkdir_fn = os.mkdir
try:
# As we know that os.mkdir is called internally by os.makedirs, we will swap the
# function in os module for the time of makedirs execution on Windows.
os.mkdir = mkdir # type: ignore
return os.makedirs(file_path, mode)
finally:
os.mkdir = orig_mkdir_fn
finally:
umask(current_umask)
def mkdir(file_path: str, mode: int = 0o777) -> None:
"""
Rewrite of original os.mkdir function, that will ensure on Windows that given mode
is correctly applied.
:param str file_path: The file path to open
:param int mode: POSIX mode to apply on directory when created, Python defaults
will be applied if ``None``
"""
if POSIX_MODE:
return os.mkdir(file_path, mode)
attributes = win32security.SECURITY_ATTRIBUTES()
security = attributes.SECURITY_DESCRIPTOR
user = _get_current_user()
dacl = _generate_dacl(user, mode, _WINDOWS_UMASK.mask)
security.SetSecurityDescriptorOwner(user, False)
security.SetSecurityDescriptorDacl(1, dacl, 0)
try:
win32file.CreateDirectory(file_path, attributes)
except pywintypes.error as err:
# Handle native windows error into python error to be consistent with the API
# of os.mkdir in the situation of a directory already existing.
if err.winerror == winerror.ERROR_ALREADY_EXISTS:
raise OSError(errno.EEXIST, err.strerror, file_path, err.winerror)
raise err
return None
def replace(src: str, dst: str) -> None:
"""
Rename a file to a destination path and handles situations where the destination exists.
:param str src: The current file path.
:param str dst: The new file path.
"""
if hasattr(os, 'replace'):
# Use replace if possible. Since we don't support Python 2 on Windows
# and os.replace() was added in Python 3.3, we can assume that
# os.replace() is always available on Windows.
getattr(os, 'replace')(src, dst)
else:
# Otherwise, use os.rename() that behaves like os.replace() on Linux.
os.rename(src, dst)
def realpath(file_path: str) -> str:
"""
Find the real path for the given path. This method resolves symlinks, including
recursive symlinks, and is protected against symlinks that creates an infinite loop.
:param str file_path: The path to resolve
:returns: The real path for the given path
:rtype: str
"""
original_path = file_path
# Since Python 3.8, os.path.realpath also resolves symlinks on Windows.
if POSIX_MODE or sys.version_info >= (3, 8):
path = os.path.realpath(file_path)
if os.path.islink(path):
# If path returned by realpath is still a link, it means that it failed to
# resolve the symlink because of a loop.
# See realpath code: https://github.com/python/cpython/blob/master/Lib/posixpath.py
raise RuntimeError('Error, link {0} is a loop!'.format(original_path))
return path
inspected_paths: List[str] = []
while os.path.islink(file_path):
link_path = file_path
file_path = os.readlink(file_path)
if not os.path.isabs(file_path):
file_path = os.path.join(os.path.dirname(link_path), file_path)
if file_path in inspected_paths:
raise RuntimeError('Error, link {0} is a loop!'.format(original_path))
inspected_paths.append(file_path)
return os.path.abspath(file_path)
def readlink(link_path: str) -> str:
"""
Return a string representing the path to which the symbolic link points.
:param str link_path: The symlink path to resolve
:return: The path the symlink points to
:returns: str
:raise: ValueError if a long path (260> characters) is encountered on Windows
"""
path = os.readlink(link_path)
if POSIX_MODE or not path.startswith('\\\\?\\'):
return path
# At this point, we know we are on Windows and that the path returned uses
# the extended form which is done for all paths in Python 3.8+
# Max length of a normal path is 260 characters on Windows, including the non printable
# termination character "<NUL>". The termination character is not included in Python
# strings, giving a max length of 259 characters, + 4 characters for the extended form
# prefix, to an effective max length 263 characters on a string representing a normal path.
if len(path) < 264:
return path[4:]
raise ValueError("Long paths are not supported by Certbot on Windows.")
# On Windows is_executable run from an unprivileged shell may claim that a path is
# executable when it is executable only if run from a privileged shell. This result
# is due to the fact that GetEffectiveRightsFromAcl calculate effective rights
# without taking into consideration if the target user has currently required the
# elevated privileges or not. However this is not a problem since certbot always
# requires to be run under a privileged shell, so the user will always benefit
# from the highest (privileged one) set of permissions on a given file.
def is_executable(path: str) -> bool:
"""
Is path an executable file?
:param str path: path to test
:return: True if path is an executable file
:rtype: bool
"""
if POSIX_MODE:
return os.path.isfile(path) and os.access(path, os.X_OK)
return _win_is_executable(path)
def has_world_permissions(path: str) -> bool:
"""
Check if everybody/world has any right (read/write/execute) on a file given its path.
:param str path: path to test
:return: True if everybody/world has any right to the file
:rtype: bool
"""
if POSIX_MODE:
return bool(stat.S_IMODE(os.stat(path).st_mode) & stat.S_IRWXO)
security = win32security.GetFileSecurity(path, win32security.DACL_SECURITY_INFORMATION)
dacl = security.GetSecurityDescriptorDacl()
return bool(dacl.GetEffectiveRightsFromAcl({
'TrusteeForm': win32security.TRUSTEE_IS_SID,
'TrusteeType': win32security.TRUSTEE_IS_USER,
'Identifier': win32security.ConvertStringSidToSid('S-1-1-0'),
}))
def compute_private_key_mode(old_key: str, base_mode: int) -> int:
"""
Calculate the POSIX mode to apply to a private key given the previous private key.
:param str old_key: path to the previous private key
:param int base_mode: the minimum modes to apply to a private key
:return: the POSIX mode to apply
:rtype: int
"""
if POSIX_MODE:
# On Linux, we keep read/write/execute permissions
# for group and read permissions for everybody.
old_mode = (stat.S_IMODE(os.stat(old_key).st_mode) &
(stat.S_IRGRP | stat.S_IWGRP | stat.S_IXGRP | stat.S_IROTH))
return base_mode | old_mode
# On Windows, the mode returned by os.stat is not reliable,
# so we do not keep any permission from the previous private key.
return base_mode
def has_same_ownership(path1: str, path2: str) -> bool:
"""
Return True if the ownership of two files given their respective path is the same.
On Windows, ownership is checked against owner only, since files do not have a group owner.
:param str path1: path to the first file
:param str path2: path to the second file
:return: True if both files have the same ownership, False otherwise
:rtype: bool
"""
if POSIX_MODE:
stats1 = os.stat(path1)
stats2 = os.stat(path2)
return (stats1.st_uid, stats1.st_gid) == (stats2.st_uid, stats2.st_gid)
security1 = win32security.GetFileSecurity(path1, win32security.OWNER_SECURITY_INFORMATION)
user1 = security1.GetSecurityDescriptorOwner()
security2 = win32security.GetFileSecurity(path2, win32security.OWNER_SECURITY_INFORMATION)
user2 = security2.GetSecurityDescriptorOwner()
return user1 == user2
def has_min_permissions(path: str, min_mode: int) -> bool:
"""
Check if a file given its path has at least the permissions defined by the given minimal mode.
On Windows, group permissions are ignored since files do not have a group owner.
:param str path: path to the file to check
:param int min_mode: the minimal permissions expected
:return: True if the file matches the minimal permissions expectations, False otherwise
:rtype: bool
"""
if POSIX_MODE:
st_mode = os.stat(path).st_mode
return st_mode == st_mode | min_mode
# Resolve symlinks, to get a consistent result with os.stat on Linux,
# that follows symlinks by default.
path = realpath(path)
# Get owner sid of the file
security = win32security.GetFileSecurity(
path, win32security.OWNER_SECURITY_INFORMATION | win32security.DACL_SECURITY_INFORMATION)
user = security.GetSecurityDescriptorOwner()
dacl = security.GetSecurityDescriptorDacl()
min_dacl = _generate_dacl(user, min_mode)
for index in range(min_dacl.GetAceCount()):
min_ace = min_dacl.GetAce(index)
# On a given ACE, index 0 is the ACE type, 1 is the permission mask, and 2 is the SID.
# See: http://timgolden.me.uk/pywin32-docs/PyACL__GetAce_meth.html
mask = min_ace[1]
user = min_ace[2]
effective_mask = dacl.GetEffectiveRightsFromAcl({
'TrusteeForm': win32security.TRUSTEE_IS_SID,
'TrusteeType': win32security.TRUSTEE_IS_USER,
'Identifier': user,
})
if effective_mask != effective_mask | mask:
return False
return True
def _win_is_executable(path: str) -> bool:
if not os.path.isfile(path):
return False
security = win32security.GetFileSecurity(path, win32security.DACL_SECURITY_INFORMATION)
dacl = security.GetSecurityDescriptorDacl()
mode = dacl.GetEffectiveRightsFromAcl({
'TrusteeForm': win32security.TRUSTEE_IS_SID,
'TrusteeType': win32security.TRUSTEE_IS_USER,
'Identifier': _get_current_user(),
})
return mode & ntsecuritycon.FILE_GENERIC_EXECUTE == ntsecuritycon.FILE_GENERIC_EXECUTE
def _apply_win_mode(file_path: str, mode: int) -> None:
"""
This function converts the given POSIX mode into a Windows ACL list, and applies it to the
file given its path. If the given path is a symbolic link, it will resolved to apply the
mode on the targeted file.
"""
file_path = realpath(file_path)
# Get owner sid of the file
security = win32security.GetFileSecurity(file_path, win32security.OWNER_SECURITY_INFORMATION)
user = security.GetSecurityDescriptorOwner()
# New DACL, that will overwrite existing one (including inherited permissions)
dacl = _generate_dacl(user, mode)
# Apply the new DACL
security.SetSecurityDescriptorDacl(1, dacl, 0)
win32security.SetFileSecurity(file_path, win32security.DACL_SECURITY_INFORMATION, security)
def _generate_dacl(user_sid: Any, mode: int, mask: Optional[int] = None) -> Any:
if mask:
mode = mode & (0o777 - mask)
analysis = _analyze_mode(mode)
# Get standard accounts from "well-known" sid
# See the list here:
# https://support.microsoft.com/en-us/help/243330/well-known-security-identifiers-in-windows-operating-systems
system = win32security.ConvertStringSidToSid('S-1-5-18')
admins = win32security.ConvertStringSidToSid('S-1-5-32-544')
everyone = win32security.ConvertStringSidToSid('S-1-1-0')
# New dacl, without inherited permissions
dacl = win32security.ACL()
# If user is already system or admins, any ACE defined here would be superseded by
# the full control ACE that will be added after.
if user_sid not in [system, admins]:
# Handle user rights
user_flags = _generate_windows_flags(analysis['user'])
if user_flags:
dacl.AddAccessAllowedAce(win32security.ACL_REVISION, user_flags, user_sid)
# Handle everybody rights
everybody_flags = _generate_windows_flags(analysis['all'])
if everybody_flags:
dacl.AddAccessAllowedAce(win32security.ACL_REVISION, everybody_flags, everyone)
# Handle administrator rights
full_permissions = _generate_windows_flags({'read': True, 'write': True, 'execute': True})
dacl.AddAccessAllowedAce(win32security.ACL_REVISION, full_permissions, system)
dacl.AddAccessAllowedAce(win32security.ACL_REVISION, full_permissions, admins)
return dacl
def _analyze_mode(mode: int) -> Dict[str, Dict[str, int]]:
return {
'user': {
'read': mode & stat.S_IRUSR,
'write': mode & stat.S_IWUSR,
'execute': mode & stat.S_IXUSR,
},
'all': {
'read': mode & stat.S_IROTH,
'write': mode & stat.S_IWOTH,
'execute': mode & stat.S_IXOTH,
},
}
def _copy_win_ownership(src: str, dst: str) -> None:
# Resolve symbolic links
src = realpath(src)
security_src = win32security.GetFileSecurity(src, win32security.OWNER_SECURITY_INFORMATION)
user_src = security_src.GetSecurityDescriptorOwner()
security_dst = win32security.GetFileSecurity(dst, win32security.OWNER_SECURITY_INFORMATION)
# Second parameter indicates, if `False`, that the owner of the file is not provided by some
# default mechanism, but is explicitly set instead. This is obviously what we are doing here.
security_dst.SetSecurityDescriptorOwner(user_src, False)
win32security.SetFileSecurity(dst, win32security.OWNER_SECURITY_INFORMATION, security_dst)
def _copy_win_mode(src: str, dst: str) -> None:
# Resolve symbolic links
src = realpath(src)
# Copy the DACL from src to dst.
security_src = win32security.GetFileSecurity(src, win32security.DACL_SECURITY_INFORMATION)
dacl = security_src.GetSecurityDescriptorDacl()
security_dst = win32security.GetFileSecurity(dst, win32security.DACL_SECURITY_INFORMATION)
security_dst.SetSecurityDescriptorDacl(1, dacl, 0)
win32security.SetFileSecurity(dst, win32security.DACL_SECURITY_INFORMATION, security_dst)
def _generate_windows_flags(rights_desc: Dict[str, int]) -> int:
# Some notes about how each POSIX right is interpreted.
#
# For the rights read and execute, we have a pretty bijective relation between
# POSIX flags and their generic counterparts on Windows, so we use them directly
# (respectively ntsecuritycon.FILE_GENERIC_READ and ntsecuritycon.FILE_GENERIC_EXECUTE).
#
# But ntsecuritycon.FILE_GENERIC_WRITE does not correspond to what one could expect from a
# write access on Linux: for Windows, FILE_GENERIC_WRITE does not include delete, move or
# rename. This is something that requires ntsecuritycon.FILE_ALL_ACCESS.
# So to reproduce the write right as POSIX, we will apply ntsecuritycon.FILE_ALL_ACCESS
# subtracted of the rights corresponding to POSIX read and POSIX execute.
#
# Finally, having read + write + execute gives a ntsecuritycon.FILE_ALL_ACCESS,
# so a "Full Control" on the file.
#
# A complete list of the rights defined on NTFS can be found here:
# https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2003/cc783530(v=ws.10)#permissions-for-files-and-folders
flag = 0
if rights_desc['read']:
flag = flag | ntsecuritycon.FILE_GENERIC_READ
if rights_desc['write']:
flag = flag | (ntsecuritycon.FILE_ALL_ACCESS
^ ntsecuritycon.FILE_GENERIC_READ
^ ntsecuritycon.FILE_GENERIC_EXECUTE)
if rights_desc['execute']:
flag = flag | ntsecuritycon.FILE_GENERIC_EXECUTE
return flag
def _check_win_mode(file_path: str, mode: int) -> bool:
# Resolve symbolic links
file_path = realpath(file_path)
# Get current dacl file
security = win32security.GetFileSecurity(file_path, win32security.OWNER_SECURITY_INFORMATION
| win32security.DACL_SECURITY_INFORMATION)
dacl = security.GetSecurityDescriptorDacl()
# Get current file owner sid
user = security.GetSecurityDescriptorOwner()
if not dacl:
# No DACL means full control to everyone
# This is not a deterministic permissions set.
return False
# Calculate the target dacl
ref_dacl = _generate_dacl(user, mode)
return _compare_dacls(dacl, ref_dacl)
def _compare_dacls(dacl1: Any, dacl2: Any) -> bool:
"""
This method compare the two given DACLs to check if they are identical.
Identical means here that they contains the same set of ACEs in the same order.
"""
return ([dacl1.GetAce(index) for index in range(dacl1.GetAceCount())] ==
[dacl2.GetAce(index) for index in range(dacl2.GetAceCount())])
def _get_current_user() -> Any:
"""
Return the pySID corresponding to the current user.
"""
# We craft the account_name ourselves instead of calling for instance win32api.GetUserNameEx,
# because this function returns nonsense values when Certbot is run under NT AUTHORITY\SYSTEM.
# To run Certbot under NT AUTHORITY\SYSTEM, you can open a shell using the instructions here:
# https://blogs.technet.microsoft.com/ben_parker/2010/10/27/how-do-i-run-powershell-execommand-prompt-as-the-localsystem-account-on-windows-7/
account_name = r"{0}\{1}".format(win32api.GetDomainName(), win32api.GetUserName())
# LookupAccountName() expects the system name as first parameter. By passing None to it,
# we instruct Windows to first search the matching account in the machine local accounts,
# then into the primary domain accounts, if the machine has joined a domain, then finally
# into the trusted domains accounts. This is the preferred lookup mechanism to use in Windows
# if there is no reason to use a specific lookup mechanism.
# See https://docs.microsoft.com/en-us/windows/desktop/api/winbase/nf-winbase-lookupaccountnamea
return win32security.LookupAccountName(None, account_name)[0]