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diff --git a/docs/htmldocs/NT_Security.html b/docs/htmldocs/NT_Security.html new file mode 100644 index 00000000000..ab8797563e3 --- /dev/null +++ b/docs/htmldocs/NT_Security.html @@ -0,0 +1,783 @@ +<HTML +><HEAD +><TITLE +>UNIX Permission Bits and Windows NT Access Control Lists</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet Version 1.57"></HEAD +><BODY +CLASS="ARTICLE" +BGCOLOR="#FFFFFF" +TEXT="#000000" +LINK="#0000FF" +VLINK="#840084" +ALINK="#0000FF" +><DIV +CLASS="ARTICLE" +><DIV +CLASS="TITLEPAGE" +><H1 +CLASS="TITLE" +><A +NAME="UNIX-PERMISSIONS" +>UNIX Permission Bits and Windows NT Access Control Lists</A +></H1 +><HR></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN3" +>Viewing and changing UNIX permissions using the NT + security dialogs</A +></H1 +><P +>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.</P +><P +>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.</P +><P +>In Samba 2.0.4 and above the default value of the + parameter <A +HREF="smb.conf.5.html#NTACLSUPPORT" +TARGET="_top" +><TT +CLASS="PARAMETER" +><I +> nt acl support</I +></TT +></A +> has been changed from + <TT +CLASS="CONSTANT" +>false</TT +> to <TT +CLASS="CONSTANT" +>true</TT +>, so + manipulation of permissions is turned on by default.</P +></DIV +><DIV +CLASS="SECT1" +><HR><H1 +CLASS="SECT1" +><A +NAME="AEN12" +>How to view file security on a Samba share</A +></H1 +><P +>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 <I +CLASS="EMPHASIS" +>Properties</I +> 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 <I +CLASS="EMPHASIS" +>Security</I +>. Click on this tab and you + will see three buttons, <I +CLASS="EMPHASIS" +>Permissions</I +>, + <I +CLASS="EMPHASIS" +>Auditing</I +>, and <I +CLASS="EMPHASIS" +>Ownership</I +>. + The <I +CLASS="EMPHASIS" +>Auditing</I +> button will cause either + an error message <SPAN +CLASS="ERRORNAME" +>A requested privilege is not held + by the client</SPAN +> 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 <B +CLASS="COMMAND" +>Add</B +> button will not currently + allow a list of users to be seen.</P +></DIV +><DIV +CLASS="SECT1" +><HR><H1 +CLASS="SECT1" +><A +NAME="AEN23" +>Viewing file ownership</A +></H1 +><P +>Clicking on the <B +CLASS="COMMAND" +>"Ownership"</B +> button + brings up a dialog box telling you who owns the given file. The + owner name will be of the form :</P +><P +><B +CLASS="COMMAND" +>"SERVER\user (Long name)"</B +></P +><P +>Where <TT +CLASS="REPLACEABLE" +><I +>SERVER</I +></TT +> is the NetBIOS name of + the Samba server, <TT +CLASS="REPLACEABLE" +><I +>user</I +></TT +> is the user name of + the UNIX user who owns the file, and <TT +CLASS="REPLACEABLE" +><I +>(Long name)</I +></TT +> + is the descriptive string identifying the user (normally found in the + GECOS field of the UNIX password database). Click on the <B +CLASS="COMMAND" +>Close + </B +> button to remove this dialog.</P +><P +>If the parameter <TT +CLASS="PARAMETER" +><I +>nt acl support</I +></TT +> + is set to <TT +CLASS="CONSTANT" +>false</TT +> then the file owner will + be shown as the NT user <B +CLASS="COMMAND" +>"Everyone"</B +>.</P +><P +>The <B +CLASS="COMMAND" +>Take Ownership</B +> 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 privileged + operation in UNIX, available only to the <I +CLASS="EMPHASIS" +>root</I +> + 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.</P +><P +>There is an NT chown command that will work with Samba + and allow a user with Administrator privilege 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 <I +CLASS="EMPHASIS" +>Seclib + </I +> NT security library written by Jeremy Allison of + the Samba Team, available from the main Samba ftp site.</P +></DIV +><DIV +CLASS="SECT1" +><HR><H1 +CLASS="SECT1" +><A +NAME="AEN43" +>Viewing file or directory permissions</A +></H1 +><P +>The third button is the <B +CLASS="COMMAND" +>"Permissions"</B +> + 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 :</P +><P +><B +CLASS="COMMAND" +>"SERVER\user (Long name)"</B +></P +><P +>Where <TT +CLASS="REPLACEABLE" +><I +>SERVER</I +></TT +> is the NetBIOS name of + the Samba server, <TT +CLASS="REPLACEABLE" +><I +>user</I +></TT +> is the user name of + the UNIX user who owns the file, and <TT +CLASS="REPLACEABLE" +><I +>(Long name)</I +></TT +> + is the descriptive string identifying the user (normally found in the + GECOS field of the UNIX password database).</P +><P +>If the parameter <TT +CLASS="PARAMETER" +><I +>nt acl support</I +></TT +> + is set to <TT +CLASS="CONSTANT" +>false</TT +> then the file owner will + be shown as the NT user <B +CLASS="COMMAND" +>"Everyone"</B +> and the + permissions will be shown as NT "Full Control".</P +><P +>The permissions field is displayed differently for files + and directories, so I'll describe the way file permissions + are displayed first.</P +><DIV +CLASS="SECT2" +><HR><H2 +CLASS="SECT2" +><A +NAME="AEN58" +>File Permissions</A +></H2 +><P +>The standard UNIX user/group/world triple and + the corresponding "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 <B +CLASS="COMMAND" +>Everyone</B +>, followed + by the list of permissions allowed for UNIX world. The UNIX + owner and group permissions are displayed as an NT + <B +CLASS="COMMAND" +>user</B +> icon and an NT <B +CLASS="COMMAND" +>local + group</B +> icon respectively followed by the list + of permissions allowed for the UNIX user and group.</P +><P +>As many UNIX permission sets don't map into common + NT names such as <B +CLASS="COMMAND" +>"read"</B +>, <B +CLASS="COMMAND" +> "change"</B +> or <B +CLASS="COMMAND" +>"full control"</B +> then + usually the permissions will be prefixed by the words <B +CLASS="COMMAND" +> "Special Access"</B +> in the NT display list.</P +><P +>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 <B +CLASS="COMMAND" +>"Take Ownership"</B +> ACL attribute + (which has no meaning in UNIX) and reports a component with + no permissions as having the NT <B +CLASS="COMMAND" +>"O"</B +> 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.</P +></DIV +><DIV +CLASS="SECT2" +><HR><H2 +CLASS="SECT2" +><A +NAME="AEN72" +>Directory Permissions</A +></H2 +><P +>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 <B +CLASS="COMMAND" +>"RW"</B +> + 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.</P +><P +>The second set of directory permissions has no real meaning + in the UNIX permissions world and represents the <B +CLASS="COMMAND" +> "inherited"</B +> permissions that any file created within + this directory would inherit.</P +><P +>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.</P +></DIV +></DIV +><DIV +CLASS="SECT1" +><HR><H1 +CLASS="SECT1" +><A +NAME="AEN79" +>Modifying file or directory permissions</A +></H1 +><P +>Modifying file and directory permissions is as simple + as changing the displayed permissions in the dialog box, and + clicking the <B +CLASS="COMMAND" +>OK</B +> 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.</P +><P +>If the parameter <TT +CLASS="PARAMETER" +><I +>nt acl support</I +></TT +> + is set to <TT +CLASS="CONSTANT" +>false</TT +> then any attempt to set + security permissions will fail with an <B +CLASS="COMMAND" +>"Access Denied" + </B +> message.</P +><P +>The first thing to note is that the <B +CLASS="COMMAND" +>"Add"</B +> + button will not return a list of users in Samba 2.0.4 (it will give + an error message of <B +CLASS="COMMAND" +>"The remote procedure call failed + and did not execute"</B +>). 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.</P +><P +>If a permission triple (either user, group, or world) + is removed from the list of permissions in the NT dialog box, + then when the <B +CLASS="COMMAND" +>"OK"</B +> 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 <B +CLASS="COMMAND" +>"O"</B +> 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.</P +><P +>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.</P +><P +>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 <B +CLASS="COMMAND" +>"Replace + permissions on existing files"</B +> checkbox in the NT + dialog before clicking <B +CLASS="COMMAND" +>"OK"</B +>.</P +><P +>If you wish to remove all permissions from a + user/group/world component then you may either highlight the + component and click the <B +CLASS="COMMAND" +>"Remove"</B +> button, + or set the component to only have the special <B +CLASS="COMMAND" +>"Take + Ownership"</B +> permission (displayed as <B +CLASS="COMMAND" +>"O" + </B +>) highlighted.</P +></DIV +><DIV +CLASS="SECT1" +><HR><H1 +CLASS="SECT1" +><A +NAME="AEN101" +>Interaction with the standard Samba create mask + parameters</A +></H1 +><P +>Note that with Samba 2.0.5 there are four new parameters + to control this interaction. These are :</P +><P +><TT +CLASS="PARAMETER" +><I +>security mask</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>force security mode</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>directory security mask</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>force directory security mode</I +></TT +></P +><P +>Once a user clicks <B +CLASS="COMMAND" +>"OK"</B +> 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 <A +HREF="smb.conf.5.html#SECURITYMASK" +TARGET="_top" +> + <TT +CLASS="PARAMETER" +><I +>security mask</I +></TT +></A +> parameter. Any bits that + were changed that are not set to '1' in this parameter are left alone + in the file permissions.</P +><P +>Essentially, zero bits in the <TT +CLASS="PARAMETER" +><I +>security mask</I +></TT +> + mask may be treated as a set of bits the user is <I +CLASS="EMPHASIS" +>not</I +> + allowed to change, and one bits are those the user is allowed to change. + </P +><P +>If not set explicitly this parameter is set to the same value as + the <A +HREF="smb.conf.5.html#CREATEMASK" +TARGET="_top" +><TT +CLASS="PARAMETER" +><I +>create mask + </I +></TT +></A +> 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.</P +><P +>Next Samba checks the changed permissions for a file against + the bits set in the <A +HREF="smb.conf.5.html#FORCESECURITYMODE" +TARGET="_top" +> <TT +CLASS="PARAMETER" +><I +>force security mode</I +></TT +></A +> parameter. Any bits + that were changed that correspond to bits set to '1' in this parameter + are forced to be set.</P +><P +>Essentially, bits set in the <TT +CLASS="PARAMETER" +><I +>force security mode + </I +></TT +> parameter may be treated as a set of bits that, when + modifying security on a file, the user has always set to be 'on'.</P +><P +>If not set explicitly this parameter is set to the same value + as the <A +HREF="smb.conf.5.html#FORCECREATEMODE" +TARGET="_top" +><TT +CLASS="PARAMETER" +><I +>force + create mode</I +></TT +></A +> 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.</P +><P +>The <TT +CLASS="PARAMETER" +><I +>security mask</I +></TT +> and <TT +CLASS="PARAMETER" +><I +>force + security mode</I +></TT +> parameters are applied to the change + request in that order.</P +><P +>For a directory Samba will perform the same operations as + described above for a file except using the parameter <TT +CLASS="PARAMETER" +><I +> directory security mask</I +></TT +> instead of <TT +CLASS="PARAMETER" +><I +>security + mask</I +></TT +>, and <TT +CLASS="PARAMETER" +><I +>force directory security mode + </I +></TT +> parameter instead of <TT +CLASS="PARAMETER" +><I +>force security mode + </I +></TT +>.</P +><P +>The <TT +CLASS="PARAMETER" +><I +>directory security mask</I +></TT +> parameter + by default is set to the same value as the <TT +CLASS="PARAMETER" +><I +>directory mask + </I +></TT +> parameter and the <TT +CLASS="PARAMETER" +><I +>force directory security + mode</I +></TT +> parameter by default is set to the same value as + the <TT +CLASS="PARAMETER" +><I +>force directory mode</I +></TT +> parameter to provide + compatibility with Samba 2.0.4 where the permission change facility + was introduced.</P +><P +>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.</P +><P +>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 <A +HREF="smb.conf.5.html" +TARGET="_top" +><TT +CLASS="FILENAME" +>smb.conf(5) + </TT +></A +> file in that share specific section :</P +><P +><TT +CLASS="PARAMETER" +><I +>security mask = 0777</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>force security mode = 0</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>directory security mask = 0777</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>force directory security mode = 0</I +></TT +></P +><P +>As described, in Samba 2.0.4 the parameters :</P +><P +><TT +CLASS="PARAMETER" +><I +>create mask</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>force create mode</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>directory mask</I +></TT +></P +><P +><TT +CLASS="PARAMETER" +><I +>force directory mode</I +></TT +></P +><P +>were used instead of the parameters discussed here.</P +></DIV +><DIV +CLASS="SECT1" +><HR><H1 +CLASS="SECT1" +><A +NAME="AEN165" +>Interaction with the standard Samba file attribute + mapping</A +></H1 +><P +>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. + </P +><P +>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.</P +><P +>What this can mean is that if the owner changes the permissions + to allow themselves read access using the security dialog, clicks + <B +CLASS="COMMAND" +>"OK"</B +> to get back to the standard attributes tab + dialog, and then clicks <B +CLASS="COMMAND" +>"OK"</B +> 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 <B +CLASS="COMMAND" +>"OK"</B +> to get back to the + attributes dialog you should always hit <B +CLASS="COMMAND" +>"Cancel"</B +> + rather than <B +CLASS="COMMAND" +>"OK"</B +> to ensure that your changes + are not overridden.</P +></DIV +></DIV +></BODY +></HTML +>
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