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diff --git a/docs/textdocs/NT_Security.txt b/docs/textdocs/NT_Security.txt deleted file mode 100644 index 4620dd8408..0000000000 --- a/docs/textdocs/NT_Security.txt +++ /dev/null @@ -1,304 +0,0 @@ - -TITLE INFORMATION: Viewing and changing UNIX permissions using the NT security dialogs in Samba 2.0.4 -AUTHOR INFORMATION: Jeremy Allison, Samba Team -DATE INFORMATION: 12th April 1999 - -Table of Contents - -Viewing and changing UNIX permissions using the NT security dialogs - -------------------------------------------------------------------- - -New in the Samba 2.0.4 release is the -ability for Windows NT clients to use their native security -settings dialog box to view and modify the underlying UNIX -permissions. - -Note that this ability is careful not to compromise the security -of the UNIX host Samba is running on, and still obeys all the -file permission rules that a Samba administrator can set. - -In Samba 2.0.4 and above the default value of the parameter -"nt acl support" has been -changed from "false" to "true", so manipulation of permissions is -turned on by default. - -How to view file security on a Samba share - ------------------------------------------- - -From an NT 4.0 client, single-click with the right mouse button on -any file or directory in a Samba mounted drive letter or UNC path. -When the menu pops-up, click on the Properties entry at the -bottom of the menu. This brings up the normal file properties dialog -box, but with Samba 2.0.4 this will have a new tab along the top -marked Security. Click on this tab and you will see three buttons, -Permissions, Auditing, and Ownership. The Auditing -button will cause either an error message "A requested privilege is -not held by the client" to appear if the user is not the NT Administrator, -or a dialog which is intended to allow an Administrator to add -auditing requirements to a file if the user is logged on as the -NT Administrator. This dialog is non-functional with a Samba -share at this time, as the only useful button, the Add button -will not currently allow a list of users to be seen. - -Viewing file ownership - ----------------------- - -Clicking on the "Ownership" button brings up a dialog box telling -you who owns the given file. The owner name will be of the form : - -"SERVER\user (Long name)" - -Where SERVER is the NetBIOS name of the Samba server, user -is the user name of the UNIX user who owns the file, and (Long name) -is the discriptive string identifying the user (normally found in the -GECOS field of the UNIX password database). Click on the Close -button to remove this dialog. - -If the parameter "nt acl support" -is set to "false" then the file owner will be shown as the NT user -"Everyone". - -The Take Ownership button will not allow you to change the -ownership of this file to yourself (clicking on it will display a -dialog box complaining that the user you are currently logged onto -the NT client cannot be found). The reason for this is that changing -the ownership of a file is a privilaged operation in UNIX, available -only to the root user. As clicking on this button causes NT to -attempt to change the ownership of a file to the current user logged -into the NT client this will not work with Samba at this time. - -There is an NT chown command that will work with Samba and allow -a user with Administrator privillage connected to a Samba 2.0.4 -server as root to change the ownership of files on both a local NTFS -filesystem or remote mounted NTFS or Samba drive. This is available -as part of the Seclib NT security library written by Jeremy -Allison of the Samba Team, available from the main Samba ftp site. - -Viewing file or directory permissions - -------------------------------------- - -The third button is the "Permissions" button. Clicking on this -brings up a dialog box that shows both the permissions and the UNIX -owner of the file or directory. The owner is displayed in the form : - -"SERVER\user (Long name)" - -Where SERVER is the NetBIOS name of the Samba server, user -is the user name of the UNIX user who owns the file, and (Long name) -is the discriptive string identifying the user (normally found in the -GECOS field of the UNIX password database). - -If the parameter "nt acl support" -is set to "false" then the file owner will be shown as the NT user -"Everyone" and the permissions will be shown as NT "Full Control". - -The permissions field is displayed differently for files and directories, -so I'll describe the way file permissions are displayed first. - -File Permissions - ----------------- - -The standard UNIX user/group/world triple and the correspinding -"read", "write", "execute" permissions triples are mapped by Samba -into a three element NT ACL with the 'r', 'w', and 'x' bits mapped -into the corresponding NT permissions. The UNIX world permissions are mapped -into the global NT group Everyone, followed by the list of permissions -allowed for UNIX world. The UNIX owner and group permissions -are displayed as an NT user icon and an NT local group icon -respectively followed by the list of permissions allowed for the -UNIX user and group. - -As many UNIX permission sets don't map into common NT names such as -"read", "change" or "full control" then usually the permissions -will be prefixed by the words "Special Access" in the NT display -list. - -But what happens if the file has no permissions allowed for a -particular UNIX user group or world component ? In order to -allow "no permissions" to be seen and modified then Samba overloads -the NT "Take Ownership" ACL attribute (which has no meaning in -UNIX) and reports a component with no permissions as having the NT -"O" bit set. This was chosen of course to make it look like a -zero, meaning zero permissions. More details on the decision behind -this will be given below. - -Directory Permissions - ---------------------- - -Directories on an NT NTFS file system have two different sets of -permissions. The first set of permissions is the ACL set on the -directory itself, this is usually displayed in the first set of -parentheses in the normal "RW" NT style. This first set of -permissions is created by Samba in exactly the same way as normal -file permissions are, described above, and is displayed in the -same way. - -The second set of directory permissions has no real meaning in the -UNIX permissions world and represents the "inherited" permissions -that any file created within this directory would inherit. - -Samba synthesises these inherited permissions for NT by returning as -an NT ACL the UNIX permission mode that a new file created by Samba -on this share would receive. - -Modifying file or directory permissions - ---------------------------------------- - -Modifying file and directory permissions is as simple as changing -the displayed permissions in the dialog box, and clicking the OK -button. However, there are limitations that a user needs to be aware -of, and also interactions with the standard Samba permission masks -and mapping of DOS attributes that need to also be taken into account. - -If the parameter "nt acl support" -is set to "false" then any attempt to set security permissions will -fail with an "Access Denied" message. - -The first thing to note is that the "Add" button will not return -a list of users in Samba 2.0.4 (it will give an error message of -"The remote proceedure call failed and did not execute"). This -means that you can only manipulate the current user/group/world -permissions listed in the dialog box. This actually works quite well -as these are the only permissions that UNIX actually has. - -If a permission triple (either user, group, or world) is removed from -the list of permissions in the NT dialog box, then when the "OK" -button is pressed it will be applied as "no permissions" on the UNIX -side. If you then view the permissions again the "no permissions" entry -will appear as the NT "O" flag, as described above. This allows you -to add permissions back to a file or directory once you have removed -them from a triple component. - -As UNIX supports only the "r", "w" and "x" bits of an NT ACL -then if other NT security attributes such as "Delete access" -are selected then they will be ignored when applied on the -Samba server. - -When setting permissions on a directory the second set of permissions -(in the second set of parentheses) is by default applied to all -files within that directory. If this is not what you want you -must uncheck the "Replace permissions on existing files" checkbox -in the NT dialog before clicking "OK". - -If you wish to remove all permissions from a user/group/world -component then you may either highlight the component and click -the "Remove" button, or set the component to only have the special -"Take Ownership" permission (dsplayed as "O") highlighted. - -Interaction with the standard Samba create mask parameters - ----------------------------------------------------------- - -Note that with Samba 2.0.5 there are four new parameters to -control this interaction. - -These are : - -security mask -force security mode -directory security mask -force directory security mode - -Once a user clicks "OK" to apply the permissions Samba maps -the given permissions into a user/group/world r/w/x triple set, -and then will check the changed permissions for a file against -the bits set in the "security mask" -parameter. Any bits that were changed that are not set to '1' -in this parameter are left alone in the file permissions. - -Essentially, zero bits in the "security mask" -mask may be treated as a set of bits the user is not allowed to change, -and one bits are those the user is allowed to change. - -If not set explicitly this parameter is set to the same value as the -"create mask" parameter to provide compatibility -with Samba 2.0.4 where this permission change facility was introduced. -To allow a user to modify all the user/group/world permissions on a file, -set this parameter to 0777. - -Next Samba checks the changed permissions for a file against the -bits set in the "force security mode" -parameter. Any bits that were changed that correspond to bits set -to '1' in this parameter are forced to be set. - -Essentially, bits set in the "force security mode" -parameter may be treated as a set of bits that, when modifying security on a file, the -user has always set to be 'on'. - -If not set explicitly this parameter is set to the same value as the -"force create mode" parameter to provide compatibility -with Samba 2.0.4 where the permission change facility was introduced. -To allow a user to modify all the user/group/world permissions on a file, -with no restrictions set this parameter to 000. - -The "security mask" and -"force security mode" parameters -are applied to the change request in that order. - -For a directory Samba will perform the same operations as described above -for a file except using the parameter "directory security mask" -instead of "security mask", and -"force directory security mode" parameter instead -of "force security mode". - -The "directory security mask" -parameter by default is set to the same value as the "directory mask" -parameter and the "force directory security mode" -parameter by default is set to the same value as the -iurl("force directory mode")(smb.conf.5.html#forcedirectorymode) parameter -to provide compatibility with Samba 2.0.4 where the permission change facility was introduced. - -In this way Samba enforces the permission restrictions that an administrator -can set on a Samba share, whilst still allowing users to modify the -permission bits within that restriction. - -If you want to set up a share that allows users full control -in modifying the permission bits on their files and directories and -doesn't force any particular bits to be set 'on', then set the following -parameters in the smb.conf.5 file in -that share specific section : - -security mask = 0777 -force security mode = 0 -directory security mask = 0777 -force directory security mode = 0 - -As described, in Samba 2.0.4 the parameters : - -create mask -force create mode -directory mask -force directory mode - -were used instead of the parameters discussed here. - -Interaction with the standard Samba file attribute mapping - ----------------------------------------------------------- - -Samba maps some of the DOS attribute bits (such as "read only") -into the UNIX permissions of a file. This means there can be a -conflict between the permission bits set via the security dialog -and the permission bits set by the file attribute mapping. - -One way this can show up is if a file has no UNIX read access -for the owner it will show up as "read only" in the standard -file attributes tabbed dialog. Unfortunately this dialog is -the same one that contains the security info in another tab. - -What this can mean is that if the owner changes the permissions -to allow themselves read access using the security dialog, clicks -"OK" to get back to the standard attributes tab dialog, and -then clicks "OK" on that dialog, then NT will set the file -permissions back to read-only (as that is what the attributes -still say in the dialog). This means that after setting permissions -and clicking "OK" to get back to the attributes dialog you -should always hit "Cancel" rather than "OK" to ensure -that your changes are not overridden. |