jcifs.smb
Class ACE

java.lang.Object
  jcifs.smb.ACE

public class ACE

extends java.lang.Object

An Access Control Entry (ACE) is an element in a security descriptor such as those associated with files and directories. The Windows OS determines which users have the necessary permissions to access objects based on these entries.

To fully understand the information exposed by this class a description of the access check algorithm used by Windows is required. The following is a basic description of the algorithm. For a more complete description we recommend reading the section on Access Control in Keith Brown's "The .NET Developer's Guide to Windows Security" (which is also available online).

Direct ACEs are evaluated first in order. The SID of the user performing the operation and the desired access bits are compared to the SID and access mask of each ACE. If the SID matches, the allow/deny flags and access mask are considered. If the ACE is a "deny" ACE and any of the desired access bits match bits in the access mask of the ACE, the whole access check fails. If the ACE is an "allow" ACE and all of the bits in the desired access bits match bits in the access mask of the ACE, the access check is successful. Otherwise, more ACEs are evaluated until all desired access bits (combined) are "allowed". If all of the desired access bits are not "allowed" the then same process is repeated for inherited ACEs.

For example, if user WNET\alice tries to open a file with desired access bits 0x00000003 (FILE_READ_DATA | FILE_WRITE_DATA) and the target file has the following security descriptor ACEs:

 Allow WNET\alice     0x001200A9  Direct
 Allow Administrators 0x001F01FF  Inherited
 Allow SYSTEM         0x001F01FF  Inherited
 

the access check would fail because the direct ACE has an access mask of 0x001200A9 which doesn't have the FILE_WRITE_DATA bit on (bit 0x00000002). Actually, this isn't quite correct. If WNET\alice is in the local Administrators group the access check will succeed because the inherited ACE allows local Administrators both FILE_READ_DATA and FILE_WRITE_DATA access.

Field Summary

static int	DELETE
static int	FILE_APPEND_DATA
static int	FILE_DELETE
static int	FILE_EXECUTE
static int	FILE_READ_ATTRIBUTES
static int	FILE_READ_DATA
static int	FILE_READ_EA
static int	FILE_WRITE_ATTRIBUTES
static int	FILE_WRITE_DATA
static int	FILE_WRITE_EA
static int	FLAGS_CONTAINER_INHERIT
static int	FLAGS_INHERIT_ONLY
static int	FLAGS_INHERITED
static int	FLAGS_NO_PROPAGATE
static int	FLAGS_OBJECT_INHERIT
static int	GENERIC_ALL
static int	GENERIC_EXECUTE
static int	GENERIC_READ
static int	GENERIC_WRITE
static int	READ_CONTROL
static int	SYNCHRONIZE
static int	WRITE_DAC
static int	WRITE_OWNER

Constructor Summary

ACE()

Method Summary

int	getAccessMask() Returns the access mask accociated with this ACE.
java.lang.String	getApplyToText() Returns the 'Apply To' text for inheritance of ACEs on directories such as 'This folder, subfolder and files'.
int	getFlags() Returns the flags for this ACE.
SID	getSID() Return the SID associated with this ACE.
boolean	isAllow() Returns true if this ACE is an allow ACE and false if it is a deny ACE.
boolean	isInherited() Returns true if this ACE is an inherited ACE and false if it is a direct ACE.
java.lang.String	toString() Return a string represeting this ACE.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

FILE_READ_DATA

public static final int FILE_READ_DATA

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FILE_WRITE_DATA

public static final int FILE_WRITE_DATA

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FILE_APPEND_DATA

public static final int FILE_APPEND_DATA

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FILE_READ_EA

public static final int FILE_READ_EA

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FILE_WRITE_EA

public static final int FILE_WRITE_EA

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FILE_EXECUTE

public static final int FILE_EXECUTE

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FILE_DELETE

public static final int FILE_DELETE

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FILE_READ_ATTRIBUTES

public static final int FILE_READ_ATTRIBUTES

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FILE_WRITE_ATTRIBUTES

public static final int FILE_WRITE_ATTRIBUTES

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DELETE

public static final int DELETE

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READ_CONTROL

public static final int READ_CONTROL

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WRITE_DAC

public static final int WRITE_DAC

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WRITE_OWNER

public static final int WRITE_OWNER

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SYNCHRONIZE

public static final int SYNCHRONIZE

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GENERIC_ALL

public static final int GENERIC_ALL

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GENERIC_EXECUTE

public static final int GENERIC_EXECUTE

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GENERIC_WRITE

public static final int GENERIC_WRITE

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GENERIC_READ

public static final int GENERIC_READ

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FLAGS_OBJECT_INHERIT

public static final int FLAGS_OBJECT_INHERIT

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FLAGS_CONTAINER_INHERIT

public static final int FLAGS_CONTAINER_INHERIT

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FLAGS_NO_PROPAGATE

public static final int FLAGS_NO_PROPAGATE

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FLAGS_INHERIT_ONLY

public static final int FLAGS_INHERIT_ONLY

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FLAGS_INHERITED

public static final int FLAGS_INHERITED

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Constructor Detail

ACE

public ACE()

Method Detail

isAllow

public boolean isAllow()

Returns true if this ACE is an allow ACE and false if it is a deny ACE.

isInherited

public boolean isInherited()

Returns true if this ACE is an inherited ACE and false if it is a direct ACE.

Note: For reasons not fully understood, FLAGS_INHERITED may not be set within all security descriptors even though the ACE was in face inherited. If an inherited ACE is added to a parent the Windows ACL editor will rebuild all children ACEs and set this flag accordingly.

getFlags

public int getFlags()

Returns the flags for this ACE. The isInherited() method checks the FLAGS_INHERITED bit in these flags.

getApplyToText

public java.lang.String getApplyToText()

Returns the 'Apply To' text for inheritance of ACEs on directories such as 'This folder, subfolder and files'. For files the text is always 'This object only'.

getAccessMask

public int getAccessMask()

Returns the access mask accociated with this ACE. Use the constants for FILE_READ_DATA, FILE_WRITE_DATA, READ_CONTROL, GENERIC_ALL, etc with bitwise operators to determine which bits of the mask are on or off.

getSID

public SID getSID()

Return the SID associated with this ACE.

toString

public java.lang.String toString()

Return a string represeting this ACE.

Note: This function should probably be changed to return SDDL fragments but currently it does not.