| Win32::Security::ACE - Win32 ACE manipulation |
newclonedumprawAcedbmAceTypedbmObjectTyperawAceTypeaceTypedbmAceFlagsrawAceFlagsaceFlagsexplainAceFlagssidtrusteebuildRawAcebuildRawAceNamedinheritableinheritable_CONTAINERinheritable_OBJECTobjectTypedbmAccessMaskrawAccessMaskaccessMaskexplainAccessMaskcleansedAccessMask
Win32::Security::ACE - Win32 ACE manipulation
use Win32::Security::ACE;
my $ace = Win32::Security::ACE->new('FILE', $rawace);
my $ace2 = Win32::Security::ACE->new('FILE', $type, $flags, $mask, $trustee);
my $ace3 = Win32::Security::ACE->new('FILE', $type, $flags, $mask, $sid);
$ace->objectType();
$ace->aceType();
$ace->aceFlags();
$ace->accessMask();
$ace->sid();
$ace->trustee();
$ace->explainAceFlags();
$ace->explainAccessMask();
$ace->rawAce();
$ace->rawAceType();
$ace->rawAceFlags();
$ace->rawAccessMask();
my(@container_inheritable_aces) = $ace->inheritable('CONTAINER');
my(@object_inheritable_aces) = $ace->inheritable('OBJECT');
Win32::Security::ACE and its subclasses provide an interface for interacting
with Win32 ACEs (Access Control Entries). The subclasses allow for variation in
mask behavior (different privileges apply to files than apply to registry keys
and so forth) and for variation in ACE behavior (OBJECT_ACE_TYPE varieties).
Win32::Security::ACE uses the flyweight design pattern in conjunction with an
in-memory cache of demand-computed properties. The result is that parsing of
ACEs is only done once for each unique ACE, and that the ACE objects themselves
are very lightweight. Double-indirection is used in the ACE objects to provide
for mutability without invalidating the cache.
This installs as part of Win32-Security. See
Win32::Security::NamedObject for more information.
It depends upon Class::Prototyped and Data::BitMask, which should be
installable via PPM or available on CPAN. It also depends upon
Win32::Security::Raw and Win32::Security::SID , which are installed as
part of Win32-Security.
Win32::Security::ACE uses some OO tricks to boost performance and clean up
the design. Here's a quick overview of the internal architecture, should you
care! It is possible to use Win32::Security::ACE objects without
understanding or reading any of this, because the public interface is designed
to hide as much of the details as possible. After all, that's the point of OO
design. If, however, you want to boost performance or to muck about in the
internals, it's worth understanding how things were done.
Win32::Security::ACE uses multiple inheritance in a diamond pattern. This
was deemed to be the best solution to an otherwise ugly situation.
Each ACE comes in a variety of forms - six at current count - and some of these
forms (notably the OBJECT_ACE_TYPE varieties) use a different internal
structure. While the code doesn't currently support the OBJECT_ACE_TYPE
varieties, it was important to architect the code to support that for future
expansion.
Each ACE can be applied to a wide variety of Named Objects as well. For better or worse, the behavior of the Access Masks for Named Objects varies according to the type of Named Object (think files vs. Active Directory objects). This behavioral variation extends to the realm of applying inherited GENERIC Access Masks to objects.
Much internal debate (I love arguing with myself) was expended over attempting to reconcile these two orthogonal forms of variation without multiple inheritance before deciding to just bite the bullet.
The obvious ugliness is that number_of_ace_types * number_of_object_types
classes have to be created. Luckily I'd already made
Win32::Security::Recursor dependent upon Class::Prototyped, so it was
deemed acceptable to make Win32::Security::ACE and Win32::Security::ACL
dependent upon it as well.
With that in mind, the base class hierarchy looks like this:
Win32::Security::ACErawAce, new, clone, dbmAceType,
and the dbmObjectType methods.
Win32::Security::ACE::_AceType/.*[aA]ceType$/, /.*[aA]ceFlags$/, sid, trustee, buildRawAce, and
/^inheritable.*/ methods. All of the direct subclasses of _AceType are
abstract as well. The package names have been collapsed by leaving out
_AceType to keep things manageable.
Win32::Security::ACE::ACCESS_ALLOWED_ACE_TYPEWin32::Security::ACE::ACCESS_DENIED_ACE_TYPEWin32::Security::ACE::SYSTEM_AUDIT_ACE_TYPEWin32::Security::ACE::_ObjectTypeobjectType and /.*[aA]ccessMask$/ methods. In addition, as will later
be discussed, each of the following classes is responsible for storing the
cached instance data for all ACEs they run into. Just like in _AceType, all
of the direct subclasses of _ObjectType are abstract as well and the package
names have been collapsed.
The concrete classes are named Win32::Security::ACE::$objectType::$aceType
(i.e. Win32::Security::ACE::SE_FILE_OBJECT::ACCESS_ALLOWED_ACE_TYPE) and
inherit from both the Win32::Security::ACE::$objectType and
Win32::Security::ACE::$aceType classes in that order. The concrete classes
are automatically generated using Class::Prototyped.
On the typical computer systems, there are very few unique ACEs. There may be
hundred or thousands, but usually there are orders of magnitude fewer ACEs than
there are objects to which they are applied. In order to reduce the computation
involved in analyzing them, Win32::Security::ACE caches all the information
computed about each ACE in a central store (actually, multiple central stores -
one for each Named Object type) based on the binary form (rawAce). The
object returned by a call to new is a reference to a reference to the hash
for that rawAce in the central store. Because it isn't a direct reference to
the hash, it is possible to switch which hash the object points to on the fly.
This allows the Win32::Security::ACE objects to be mutable while maintaining
the immutability of the central store. It also makes each individual
Win32::Security::ACE object incredibly lightweight, since it is only composed
of a single blessed scalar. The properties are computed as needed, but the
results are cached in the central store.
For instance, once explainAccessMask has been computed for a given rawAce,
it can be found from the object as $$self->{explainAccessMask}. This
should be used with care, although in some instances it is possible to reduce
the number of method calls (should this be necessary for performance reasons) by
making calls like so:
$$ace->{explainAccessMask} || $ace->explainAccessMask();
That provides a fail-safe should the explainAccessMask value have not yet
been computed while eliminating the method call if it has been.
In order to defend against accidental manipulation, return values from the calls
(although not from the direct access, obviously) are deep-copied one layer deep.
That means that the results of $ace->explainAccessMask() can be safely
manipulated without harming the ACE, but that the results of
$$ace->{explainAccessMask} should be treated as read-only.
Win32::Security::ACE objects returned are cloned (using inlined code to
reduce the performance hit). The values returned from the /^dbm.*/ calls are
not cloned, however, so be careful there.
newCreates a new Win32::Security::ACE object.
The various calling forms are:
Win32::Security::ACE->new($objectType, $rawAce)Win32::Security::ACE->new($objectType, $aceType, @aceParams)"Win32::Security::ACE::$objectType"->new($rawAce)"Win32::Security::ACE::$objectType"->new($aceType, @aceParams)"Win32::Security::ACE::$objectType\::$aceType"->new($rawAce)"Win32::Security::ACE::$objectType\::$aceType"->new(@aceParams)$ace_object->new($rawAce)$ace_object->new(@aceParams)Note that when using $objectType and $aceType in the package name, the
values need to be canonicalized (i.e. SE_FILE_OBJECT, not the alias FILE).
Also note that the $aceType is extractable from the $rawAce. When those
values are passed as part of the parameter list, any of the valid aliases are
permitted. If the $objectType or $aceType has already been canonicalized,
improved performance can be realized by making the call on the more
fully-qualified package name and thus avoiding the calls to redo the
canonicalization. It is important that if $aceType is specified for a
$rawAce that the values match. The backslash preceding the final :: in
the final two class name calls is a fast way of ensuring that $objectType
rather than $objectType:: is the interpolated variable name.
For ACCESS_ALLOWED_ACE_TYPE, ACCESS_DENIED_ACE_TYPE, and
SYSTEM_AUDIT_ACE_TYPE, the @aceParams array consists of aceFlags,
accessMask, and either the sid or trustee. The aceType,
aceFlags, and accessMask can be passed as integers or in any acceptable
format for Data::BitMask (i.e. '|' separated constants in a string, an
anonmous array of constants, or an anonymous hash of constants). See
Data::BitMask::buildRawMask for more information.
cloneThis creates a new Win32::Security::ACE object that is identical in all
forms, except for identity, to the original object. Because of the flyweight
design pattern, this is a very inexpensive operation. However, should you wish
to avoid the overhead of a method call, you can inline the code like so:
bless(\(my $o = ${$obj}), ref($obj));
Basically, it derefences the scalar reference, assigns it to a temporary
lexical, creates a reference to that, and then blesses it into the original
package. Nifty, eh? Syntax stolen (with a few modifications) from
Data::Dumper output.
dumpThis returns a dump of the Win32::Security::ACL object in a format useful for
debugging.
rawAceReturns the binary string form of the ACE. If passed a value, changes
the binary string form of the ACE to the new value and returns $self.
dbmAceTypeReturns the Data::BitMask object for interacting with ACE Types. Standard
Win32 constants for ACE_TYPE are supported along with several aliases. The
standard ACE_TYPE constants are ACCESS_ALLOWED_ACE_TYPE,
ACCESS_DENIED_ACE_TYPE, SYSTEM_AUDIT_ACE_TYPE, SYSTEM_ALARM_ACE_TYPE,
ACCESS_ALLOWED_COMPOUND_ACE_TYPE, ACCESS_ALLOWED_OBJECT_ACE_TYPE,
ACCESS_DENIED_OBJECT_ACE_TYPE, SYSTEM_AUDIT_OBJECT_ACE_TYPE,
SYSTEM_ALARM_OBJECT_ACE_TYPE, ACCESS_MIN_MS_ACE_TYPE,
ACCESS_MAX_MS_V2_ACE_TYPE, ACCESS_MAX_MS_V3_ACE_TYPE,
ACCESS_MIN_MS_OBJECT_ACE_TYPE, ACCESS_MAX_MS_OBJECT_ACE_TYPE,
ACCESS_MAX_MS_V4_ACE_TYPE, and ACCESS_MAX_MS_ACE_TYPE.
The aliases are:
ALLOWED or ALLOW (ACCESS_ALLOWED_ACE_TYPE)
DENIED or DENY (ACCESS_DENIED_ACE_TYPE)
AUDIT (SYSTEM_AUDIT_ACE_TYPE)
dbmObjectTypeReturns the Data::BitMask object for interacting with Named Object Types.
The standard Object Types are SE_UNKNOWN_OBJECT_TYPE, SE_FILE_OBJECT,
SE_SERVICE, SE_PRINTER, SE_REGISTRY_KEY, SE_LMSHARE,
SE_KERNEL_OBJECT, SE_WINDOW_OBJECT, SE_DS_OBJECT, SE_DS_OBJECT_ALL,
and SE_PROVIDER_DEFINED_OBJECT.
There are a number of aliases as well:
FILE (SE_FILE_OBJECT)
SERVICE (SE_SERVICE)
PRINTER (SE_PRINTER)
REG (SE_REGISTRY_KEY)
REGISTRY (SE_REGISTRY_KEY)
SHARE (SE_LMSHARE)
rawAceTypeReturns the integer form of the ACE Type. Useful for equality checks with other
calls to rawAceType.
aceTypeReturns the Data::BitMask::explain_const form of the ACE Type (i.e. a string
constant, such as 'ACCESS_ALLOWED_ACE_TYPE' or 'ACCESS_DENIED_ACE_TYPE').
dbmAceFlagsReturns the Data::BitMask object for interacting with ACE Flags. Standard
Win32 constants for ACE_FLAGS are supported along with some aliases. The
standard ACE_FLAGS constants are OBJECT_INHERIT_ACE,
CONTAINER_INHERIT_ACE, NO_PROPAGATE_INHERIT_ACE, INHERIT_ONLY_ACE,
INHERITED_ACE, SUCCESSFUL_ACCESS_ACE_FLAG, and FAILED_ACCESS_ACE_FLAG.
The aliases are:
SUBFOLDERS_AND_FILES_ONLY (CONTAINER_INHERIT_ACE | INHERIT_ONLY_ACE | OBJECT_INHERIT_ACE)
FULL_INHERIT or FI (OBJECT_INHERIT_ACE | CONTAINER_INHERIT_ACE)
FILES_ONLY (INHERIT_ONLY_ACE | OBJECT_INHERIT_ACE)
SUBFOLDERS_ONLY (CONTAINER_INHERIT_ACE | INHERIT_ONLY_ACE)
CI (CONTAINER_INHERIT_ACE)
OI (OBJECT_INHERIT_ACE)
IO (INHERIT_ONLY_ACE)
NP (NO_PROPAGATE_INHERIT_ACE)
rawAceFlagsReturns the integer form of the ACE Flags. Useful for equality checks with
other calls to rawAceFlags.
If called with a passed parameter, mutates the ACE to that new aceFlags value. All forms of aceFlags access accept all forms as parameters when used as a setter.
aceFlagsReturns the Data::BitMask::break_mask form of the ACE Flags (i.e. a hash
containing all matching constants for the Flags mask of the ACE).
If called with a passed parameter, mutates the ACE to that new aceFlags value. All forms of aceFlags access accept all forms as parameters when used as a setter.
explainAceFlagsReturns the Data::BitMask::explain_mask form of the ACE Flags (i.e. a hash
containing a set of constants sufficient to recreate and explain the flags mask
of the ACE).
If called with a passed parameter, mutates the ACE to that new aceFlags value. All forms of aceFlags access accept all forms as parameters when used as a setter.
sidReturns the SID in binary form. Useful for equality checks with other SIDs.
If called with a passed parameter, mutates the ACE to that new SID. Both sid
and trustee accepts SID and Trustee names as passed parameters when used as a
setter.
trusteeReturns the Trustee for the SID as generated by
Win32::Security::SID::ConvertSidToName.
If called with a passed parameter, mutates the ACE to that new trustee. Both sid
and trustee accepts SID and Trustee names as passed parameters when used as a
setter.
buildRawAceCreates a binary string ACE from parameters. This should always be called on
a full class (i.e. Win32::Security::ACE::$objectType::$aceType). Each
implementation accepts different parameters.
ACCESS_ALLOWED_ACE_TYPE, ACCESS_DENIED_ACE_TYPE, SYSTEM_AUDIT_ACE_TYPEAceFlags, AccessMask, and either Sid or Trustee.
buildRawAceNamedCreates a binary string ACE from named parameters. This should always be
called on a full class (i.e. Win32::Security::ACE::$objectType::$aceType)
or on an existing ACE. Each implementation accepts different parameters. If
called on an existing ACE, missing parameters will be supplied from the existing
ACE. As an example, to create a new rawAce value based on an existing ACE,
but with the Access Mask set to READ:
$ace->buildRawAceNamed(accessMask => 'READ');
ACCESS_ALLOWED_ACE_TYPE, ACCESS_DENIED_ACE_TYPE, SYSTEM_AUDIT_ACE_TYPEaceFlags, accessMask, and trustee (as either a SID or
Trustee name). The names are case-sensitive.
inheritableAccepts a type (either 'OBJECT' or 'CONTAINER') and calls
inheritable_OBJECT or inheritable_CONTAINER as appropriate.
Those methods return the list of ACEs that would be inherited by a newly created
child OBJECT or CONTAINER if the parent has this ACE. In most cases,
there will be either none (non-inheritable ACE) or one (inheritable ACE) ACEs
returned. In the case of ACEs that use GENERIC_.* permissions or that use
CREATOR OWNER, there may be two ACEs returned - one to implement the
permissions on that specific container, and the other to perpetuate the
inheritable ACE. In the case of an CREATOR OWNER ACE, the ACE that
implements the actual permissions on the container will be given a null SID.
The methods take care of checking the flags to determine whether the ACE should be inherited as well as adjusting the flags for any inherited ACE appropriately.
Note that it is not sufficient to simply concatenate the ACEs of a DACL to
generate the inheritable DACL because Win2K and WinXP remove occluded
permissions (for instance, if an container has an inherited permission granting
READ access to Domain Users and someone grants explicit fully-inheritable
FULL access to Domain Users to that container, child objects will not receive
the inherited READ access because it is fully occluded by the also inherited
FULL access).
inheritable_CONTAINERSee inheritable for an explanation.
inheritable_OBJECTSee inheritable for an explanation.
objectTypeReturns the type of object to which the ACE is or should be attached.
dbmAccessMaskReturns the Data::BitMask object for interacting with the Access Mask. The
default is Win32 constants for Standard Rights. Some of the Object Types define
additional rights. The Standard Rights are DELETE, READ_CONTROL,
WRITE_DAC, WRITE_OWNER, SYNCHRONIZE, STANDARD_RIGHTS_REQUIRED,
STANDARD_RIGHTS_READ, STANDARD_RIGHTS_WRITE, STANDARD_RIGHTS_EXECUTE,
STANDARD_RIGHTS_ALL, SPECIFIC_RIGHTS_ALL, ACCESS_SYSTEM_SECURITY,
MAXIMUM_ALLOWED, GENERIC_READ, GENERIC_WRITE, GENERIC_EXECUTE, and
GENERIC_ALL.
SE_FILE_OBJECTFILE_READ_DATA, FILE_LIST_DIRECTORY,
FILE_WRITE_DATA, FILE_ADD_FILE, FILE_APPEND_DATA,
FILE_ADD_SUBDIRECTORY, FILE_CREATE_PIPE_INSTANCE, FILE_READ_EA,
FILE_WRITE_EA, FILE_EXECUTE, FILE_TRAVERSE, FILE_DELETE_CHILD,
FILE_READ_ATTRIBUTES, FILE_WRITE_ATTRIBUTES, FILE_ALL_ACCESS,
FILE_GENERIC_READ, FILE_GENERIC_WRITE, and FILE_GENERIC_EXECUTE.
The aliases are:
FULL or F (STANDARD_RIGHTS_ALL | FILE_GENERIC_READ |FILE_GENERIC_WRITE | FILE_GENERIC_EXECUTE | FILE_DELETE_CHILD)
MODIFY or M (FILE_GENERIC_READ | FILE_GENERIC_WRITE | FILE_GENERIC_EXECUTE | DELETE)
READ or R (FILE_GENERIC_READ | FILE_GENERIC_EXECUTE)
SE_REGISTRY_KEYKEY_QUERY_VALUE, KEY_SET_VALUE, KEY_CREATE_SUB_KEY,
KEY_ENUMERATE_SUB_KEYS, KEY_NOTIFY, KEY_CREATE_LINK, KEY_WOW64_64,
KEY_WOW64_32KEY, KEY_READ, KEY_WRITE, KEY_EXECUTE, and
KEY_ALL_ACCESS.
SE_REGISTRY_KEY support is still under development.
rawAccessMaskReturns the integer form of the Access Mask. Useful for equality checks and
bitwise comparisons with other calls to rawmask.
If called with a passed parameter, mutates the ACE to that new accessMask value. All forms of accessMask access accept all forms as parameters when used as a setter.
accessMaskReturns the Data::BitMask::break_mask form of the Access Mask (i.e. a hash
containing all matching constants for the Access Mask of the ACE).
If called with a passed parameter, mutates the ACE to that new accessMask value. All forms of accessMask access accept all forms as parameters when used as a setter.
explainAccessMaskReturns the Data::BitMask::explain_mask form of the Access Mask (i.e. a hash
containing a set of constants sufficient to recreate and explain the Access Mask
of the ACE).
If called with a passed parameter, mutates the ACE to that new accessMask value. All forms of accessMask access accept all forms as parameters when used as a setter.
cleansedAccessMaskThis returns an Access Mask cleansed of GENERIC_ permissions for the ACE in
question. Some of the Object Types define special behavior for this.
SE_FILE_OBJECTGENERIC_READ, GENERIC_WRITE, GENERIC_EXECUTE, and
GENERIC_ALL bits and replaces them with the constants FILE_GENERIC_READ,
FILE_GENERIC_WRITE, FILE_GENERIC_EXECUTE, and FULL respectively. This
is required for correctly interpreting inheritance of some INHERIT_ONLY_ACE
ACEs.
Toby Ovod-Everett, toby@ovod-everett.org
| Win32::Security::ACE - Win32 ACE manipulation |