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+<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 15. File, Directory, and Share Access Controls</title><link rel="stylesheet" href="samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.68.1"><link rel="start" href="index.html" title="The Official Samba-3 HOWTO and Reference Guide"><link rel="up" href="optional.html" title="Part III. Advanced Configuration"><link rel="prev" href="rights.html" title="Chapter 14. User Rights and Privileges"><link rel="next" href="locking.html" title="Chapter 16. File and Record Locking"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 15. File, Directory, and Share Access Controls</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="rights.html">Prev</a> </td><th width="60%" align="center">Part III. Advanced Configuration</th><td width="20%" align="right"> <a accesskey="n" href="locking.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="AccessControls"></a>Chapter 15. File, Directory, and Share Access Controls</h2></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="othername">H.</span> <span class="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a href="mailto:jht@samba.org">jht@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Jeremy</span> <span class="surname">Allison</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a href="mailto:jra@samba.org">jra@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Jelmer</span> <span class="othername">R.</span> <span class="surname">Vernooij</span></h3><span class="contrib">drawing</span><div class="affiliation"><span class="orgname">The Samba Team<br></span><div class="address"><p><code class="email"><<a href="mailto:jelmer@samba.org">jelmer@samba.org</a>></code></p></div></div></div></div><div><p class="pubdate">May 10, 2003</p></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="AccessControls.html#id2578294">Features and Benefits</a></span></dt><dt><span class="sect1"><a href="AccessControls.html#id2578481">File System Access Controls</a></span></dt><dd><dl><dt><span class="sect2"><a href="AccessControls.html#id2578496">MS Windows NTFS Comparison with UNIX File Systems</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2578831">Managing Directories</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2578954">File and Directory Access Control</a></span></dt></dl></dd><dt><span class="sect1"><a href="AccessControls.html#id2579620">Share Definition Access Controls</a></span></dt><dd><dl><dt><span class="sect2"><a href="AccessControls.html#id2579653">User- and Group-Based Controls</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2579968">File and Directory Permissions-Based Controls</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2580261">Miscellaneous Controls</a></span></dt></dl></dd><dt><span class="sect1"><a href="AccessControls.html#id2580545">Access Controls on Shares</a></span></dt><dd><dl><dt><span class="sect2"><a href="AccessControls.html#id2580693">Share Permissions Management</a></span></dt></dl></dd><dt><span class="sect1"><a href="AccessControls.html#id2581040">MS Windows Access Control Lists and UNIX Interoperability</a></span></dt><dd><dl><dt><span class="sect2"><a href="AccessControls.html#id2581046">Managing UNIX Permissions Using NT Security Dialogs</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2581093">Viewing File Security on a Samba Share</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2581164">Viewing File Ownership</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2581303">Viewing File or Directory Permissions</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2581514">Modifying File or Directory Permissions</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2581668">Interaction with the Standard Samba “<span class="quote">create mask</span>” Parameters</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2581996">Interaction with the Standard Samba File Attribute Mapping</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2582069">Windows NT/200X ACLs and POSIX ACLs Limitations</a></span></dt></dl></dd><dt><span class="sect1"><a href="AccessControls.html#id2582481">Common Errors</a></span></dt><dd><dl><dt><span class="sect2"><a href="AccessControls.html#id2582492">Users Cannot Write to a Public Share</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2582874">File Operations Done as <span class="emphasis"><em>root</em></span> with <span class="emphasis"><em>force user</em></span> Set</a></span></dt><dt><span class="sect2"><a href="AccessControls.html#id2582911">MS Word with Samba Changes Owner of File</a></span></dt></dl></dd></dl></div><p>
+<a class="indexterm" name="id2578125"></a>
+<a class="indexterm" name="id2578132"></a>
+<a class="indexterm" name="id2578138"></a>
+<a class="indexterm" name="id2578145"></a>
+Advanced MS Windows users are frequently perplexed when file, directory, and share manipulation of
+resources shared via Samba do not behave in the manner they might expect. MS Windows network
+administrators are often confused regarding network access controls and how to
+provide users with the access they need while protecting resources from unauthorized access.
+</p><p>
+<a class="indexterm" name="id2578162"></a>
+<a class="indexterm" name="id2578169"></a>
+Many UNIX administrators are unfamiliar with the MS Windows environment and in particular
+have difficulty in visualizing what the MS Windows user wishes to achieve in attempts to set file
+and directory access permissions.
+</p><p>
+<a class="indexterm" name="id2578183"></a>
+<a class="indexterm" name="id2578190"></a>
+<a class="indexterm" name="id2578197"></a>
+<a class="indexterm" name="id2578204"></a>
+The problem lies in the differences in how file and directory permissions and controls work
+between the two environments. This difference is one that Samba cannot completely hide, even
+though it does try to bridge the chasm to a degree.
+</p><p>
+<a class="indexterm" name="id2578217"></a>
+<a class="indexterm" name="id2578224"></a>
+<a class="indexterm" name="id2578233"></a>
+<a class="indexterm" name="id2578240"></a>
+POSIX Access Control List technology has been available (along with extended attributes)
+for UNIX for many years, yet there is little evidence today of any significant use. This
+explains to some extent the slow adoption of ACLs into commercial Linux products. MS Windows
+administrators are astounded at this, given that ACLs were a foundational capability of the now
+decade-old MS Windows NT operating system.
+</p><p>
+<a class="indexterm" name="id2578257"></a>
+The purpose of this chapter is to present each of the points of control that are possible with
+Samba-3 in the hope that this will help the network administrator to find the optimum method
+for delivering the best environment for MS Windows desktop users.
+</p><p>
+<a class="indexterm" name="id2578272"></a>
+<a class="indexterm" name="id2578279"></a>
+This is an opportune point to mention that Samba was created to provide a means of interoperability
+and interchange of data between differing operating environments. Samba has no intent to change
+UNIX/Linux into a platform like MS Windows. Instead the purpose was and is to provide a sufficient
+level of exchange of data between the two environments. What is available today extends well
+beyond early plans and expectations, yet the gap continues to shrink.
+</p><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2578294"></a>Features and Benefits</h2></div></div></div><p>
+ Samba offers much flexibility in file system access management. These are the key access control
+ facilities present in Samba today:
+ </p><div class="itemizedlist"><p class="title"><b>Samba Access Control Facilities</b></p><ul type="disc"><li><p>
+ <a class="indexterm" name="id2578315"></a>
+ <span class="emphasis"><em>UNIX File and Directory Permissions</em></span>
+ </p><p>
+<a class="indexterm" name="id2578332"></a>
+<a class="indexterm" name="id2578339"></a>
+<a class="indexterm" name="id2578346"></a>
+ Samba honors and implements UNIX file system access controls. Users
+ who access a Samba server will do so as a particular MS Windows user.
+ This information is passed to the Samba server as part of the logon or
+ connection setup process. Samba uses this user identity to validate
+ whether or not the user should be given access to file system resources
+ (files and directories). This chapter provides an overview for those
+ to whom the UNIX permissions and controls are a little strange or unknown.
+ </p></li><li><p>
+ <span class="emphasis"><em>Samba Share Definitions</em></span>
+ </p><p>
+<a class="indexterm" name="id2578374"></a>
+ In configuring share settings and controls in the <code class="filename">smb.conf</code> file,
+ the network administrator can exercise overrides to native file
+ system permissions and behaviors. This can be handy and convenient
+ to effect behavior that is more like what MS Windows NT users expect,
+ but it is seldom the <span class="emphasis"><em>best</em></span> way to achieve this.
+ The basic options and techniques are described herein.
+ </p></li><li><p>
+ <span class="emphasis"><em>Samba Share ACLs</em></span>
+ <a class="indexterm" name="id2578406"></a>
+ </p><p>
+<a class="indexterm" name="id2578418"></a>
+ Just as it is possible in MS Windows NT to set ACLs on shares
+ themselves, so it is possible to do in Samba.
+ Few people make use of this facility, yet it remains one of the
+ easiest ways to affect access controls (restrictions) and can often
+ do so with minimum invasiveness compared with other methods.
+ </p></li><li><p>
+ <a class="indexterm" name="id2578436"></a>
+ <a class="indexterm" name="id2578445"></a>
+ <span class="emphasis"><em>MS Windows ACLs through UNIX POSIX ACLs</em></span>
+ </p><p>
+<a class="indexterm" name="id2578461"></a>
+ The use of POSIX ACLs on UNIX/Linux is possible only if the underlying
+ operating system supports them. If not, then this option will not be
+ available to you. Current UNIX technology platforms have native support
+ for POSIX ACLs. There are patches for the Linux kernel that also provide
+ this support. Sadly, few Linux platforms ship today with native ACLs and
+ extended attributes enabled. This chapter has pertinent information
+ for users of platforms that support them.
+ </p></li></ul></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2578481"></a>File System Access Controls</h2></div></div></div><p>
+Perhaps the most important recognition to be made is the simple fact that MS Windows NT4/200x/XP
+implement a totally divergent file system technology from what is provided in the UNIX operating system
+environment. First we consider what the most significant differences are, then we look
+at how Samba helps to bridge the differences.
+</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2578496"></a>MS Windows NTFS Comparison with UNIX File Systems</h3></div></div></div><p>
+ <a class="indexterm" name="id2578504"></a>
+ <a class="indexterm" name="id2578511"></a>
+ <a class="indexterm" name="id2578518"></a>
+ <a class="indexterm" name="id2578527"></a>
+ Samba operates on top of the UNIX file system. This means it is subject to UNIX file system conventions
+ and permissions. It also means that if the MS Windows networking environment requires file system
+ behavior, that differs from UNIX file system behavior then somehow Samba is responsible for emulating
+ that in a transparent and consistent manner.
+ </p><p>
+ It is good news that Samba does this to a large extent, and on top of that, provides a high degree
+ of optional configuration to override the default behavior. We look at some of these overrides,
+ but for the greater part we stay within the bounds of default behavior. Those wishing to explore
+ the depths of control ability should review the <code class="filename">smb.conf</code> man page.
+ </p><p>The following compares file system features for UNIX with those of MS Windows NT/200x:
+ <a class="indexterm" name="id2578562"></a>
+
+ </p><div class="variablelist"><dl><dt><span class="term">Name Space</span></dt><dd><p>
+ MS Windows NT4/200x/XP file names may be up to 254 characters long, and UNIX file names
+ may be 1023 characters long. In MS Windows, file extensions indicate particular file types;
+ in UNIX this is not so rigorously observed because all names are considered arbitrary.
+ </p><p>
+ What MS Windows calls a folder, UNIX calls a directory.
+ </p></dd><dt><span class="term">Case Sensitivity</span></dt><dd><p>
+ <a class="indexterm" name="id2578607"></a>
+ <a class="indexterm" name="id2578614"></a>
+ MS Windows file names are generally uppercase if made up of 8.3 (8-character file name
+ and 3 character extension. File names that are longer than 8.3 are case preserving and case
+ insensitive.
+ </p><p>
+ UNIX file and directory names are case sensitive and case preserving. Samba implements the
+ MS Windows file name behavior, but it does so as a user application. The UNIX file system
+ provides no mechanism to perform case-insensitive file name lookups. MS Windows does this
+ by default. This means that Samba has to carry the processing overhead to provide features
+ that are not native to the UNIX operating system environment.
+ </p><p>
+ Consider the following. All are unique UNIX names but one single MS Windows file name:
+ </p><pre class="screen">
+ MYFILE.TXT
+ MyFile.txt
+ myfile.txt
+ </pre><p>
+ So clearly, in an MS Windows file namespace these three files cannot co-exist, but in UNIX
+ they can.
+ </p><p>
+ So what should Samba do if all three are present? That which is lexically first will be
+ accessible to MS Windows users; the others are invisible and unaccessible any
+ other solution would be suicidal. The Windows client will ask for a case-insensitive file
+ lookup, and that is the reason for which Samba must offer a consistent selection in the
+ event that the UNIX directory contains multiple files that would match a case insensitive
+ file listing.
+ </p></dd><dt><span class="term">Directory Separators</span></dt><dd><p>
+ <a class="indexterm" name="id2578678"></a>
+ MS Windows and DOS use the backslash <code class="constant">\</code> as a directory delimiter, and UNIX uses
+ the forward-slash <code class="constant">/</code> as its directory delimiter. This is handled transparently by Samba.
+ </p></dd><dt><span class="term">Drive Identification</span></dt><dd><p>
+ <a class="indexterm" name="id2578706"></a>
+ MS Windows products support a notion of drive letters, like <span><strong class="command">C:</strong></span>, to represent
+ disk partitions. UNIX has no concept of separate identifiers for file partitions; each
+ such file system is mounted to become part of the overall directory tree.
+ The UNIX directory tree begins at <code class="constant">/</code> just as the root of a DOS drive is specified as
+ <code class="constant">C:\</code>.
+ </p></dd><dt><span class="term">File Naming Conventions</span></dt><dd><p>
+ <a class="indexterm" name="id2578742"></a>
+ MS Windows generally never experiences file names that begin with a dot (<code class="constant">.</code>), while in UNIX these
+ are commonly found in a user's home directory. Files that begin with a dot (<code class="constant">.</code>) are typically
+ startup files for various UNIX applications, or they may be files that contain
+ startup configuration data.
+ </p></dd><dt><span class="term">Links and Short-Cuts</span></dt><dd><p>
+ <a class="indexterm" name="id2578772"></a>
+ <a class="indexterm" name="id2578781"></a>
+ <a class="indexterm" name="id2578791"></a>
+ MS Windows make use of <span class="emphasis"><em>links and shortcuts</em></span> that are actually special types of files that will
+ redirect an attempt to execute the file to the real location of the file. UNIX knows of file and directory
+ links, but they are entirely different from what MS Windows users are used to.
+ </p><p>
+ Symbolic links are files in UNIX that contain the actual location of the data (file or directory). An
+ operation (like read or write) will operate directly on the file referenced. Symbolic links are also
+ referred to as “<span class="quote">soft links.</span>” A hard link is something that MS Windows is not familiar with. It allows
+ one physical file to be known simultaneously by more than one file name.
+ </p></dd></dl></div><p>
+ There are many other subtle differences that may cause the MS Windows administrator some temporary discomfort
+ in the process of becoming familiar with UNIX/Linux. These are best left for a text that is dedicated to the
+ purpose of UNIX/Linux training and education.
+ </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2578831"></a>Managing Directories</h3></div></div></div><p>
+<a class="indexterm" name="id2578839"></a>
+<a class="indexterm" name="id2578846"></a>
+<a class="indexterm" name="id2578853"></a>
+ There are three basic operations for managing directories: <span><strong class="command">create</strong></span>, <span><strong class="command">delete</strong></span>,
+ <span><strong class="command">rename</strong></span>. <a href="AccessControls.html#TOSH-Accesstbl" title="Table 15.1. Managing Directories with UNIX and Windows">Managing Directories with UNIX and
+ Windows</a> compares the commands in Windows and UNIX that implement these operations.
+ </p><div class="table"><a name="TOSH-Accesstbl"></a><p class="title"><b>Table 15.1. Managing Directories with UNIX and Windows</b></p><table summary="Managing Directories with UNIX and Windows" border="1"><colgroup><col><col><col></colgroup><thead><tr><th align="center">Action</th><th align="center">MS Windows Command</th><th align="center">UNIX Command</th></tr></thead><tbody><tr><td align="center">create</td><td align="center">md folder</td><td align="center">mkdir folder</td></tr><tr><td align="center">delete</td><td align="center">rd folder</td><td align="center">rmdir folder</td></tr><tr><td align="center">rename</td><td align="center">rename oldname newname</td><td align="center">mv oldname newname</td></tr></tbody></table></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2578954"></a>File and Directory Access Control</h3></div></div></div><p>
+ <a class="indexterm" name="id2578962"></a>
+<a class="indexterm" name="id2578972"></a>
+<a class="indexterm" name="id2578978"></a>
+ The network administrator is strongly advised to read basic UNIX training manuals and reference materials
+ regarding file and directory permissions maintenance. Much can be achieved with the basic UNIX permissions
+ without having to resort to more complex facilities like POSIX ACLs or extended attributes (EAs).
+ </p><p>
+ UNIX/Linux file and directory access permissions involves setting three primary sets of data and one control set.
+ A UNIX file listing looks as follows:
+</p><pre class="screen">
+<code class="prompt">$ </code><strong class="userinput"><code>ls -la</code></strong>
+total 632
+drwxr-xr-x 13 maryo gnomes 816 2003-05-12 22:56 .
+drwxrwxr-x 37 maryo gnomes 3800 2003-05-12 22:29 ..
+dr-xr-xr-x 2 maryo gnomes 48 2003-05-12 22:29 muchado02
+drwxrwxrwx 2 maryo gnomes 48 2003-05-12 22:29 muchado03
+drw-rw-rw- 2 maryo gnomes 48 2003-05-12 22:29 muchado04
+d-w--w--w- 2 maryo gnomes 48 2003-05-12 22:29 muchado05
+dr--r--r-- 2 maryo gnomes 48 2003-05-12 22:29 muchado06
+drwsrwsrwx 2 maryo gnomes 48 2003-05-12 22:29 muchado08
+---------- 1 maryo gnomes 1242 2003-05-12 22:31 mydata00.lst
+--w--w--w- 1 maryo gnomes 7754 2003-05-12 22:33 mydata02.lst
+-r--r--r-- 1 maryo gnomes 21017 2003-05-12 22:32 mydata04.lst
+-rw-rw-rw- 1 maryo gnomes 41105 2003-05-12 22:32 mydata06.lst
+<code class="prompt">$ </code>
+</pre><p>
+ </p><p>
+ The columns represent (from left to right) permissions, number of hard links to file, owner, group, size
+ (bytes), access date, time of last modification, and file name.
+ </p><p>
+ An overview of the permissions field is shown in <a href="AccessControls.html#access1" title="Figure 15.1. Overview of UNIX permissions field.">Overview of UNIX permissions
+ field</a>.
+ </p><div class="figure"><a name="access1"></a><p class="title"><b>Figure 15.1. Overview of UNIX permissions field.</b></p><div class="mediaobject"><img src="images/access1.png" width="216" alt="Overview of UNIX permissions field."></div></div><p>
+ Any bit flag may be unset. An unset bit flag is the equivalent of "cannot" and is represented
+ as a “<span class="quote">-</span>” character (see <a href="AccessControls.html#access2" title="Example 15.1. Example File">???</a>)
+<a class="indexterm" name="id2579120"></a>
+<a class="indexterm" name="id2579127"></a>
+<a class="indexterm" name="id2579134"></a>
+<a class="indexterm" name="id2579140"></a>
+<a class="indexterm" name="id2579147"></a>
+<a class="indexterm" name="id2579154"></a>
+ </p><div class="example"><a name="access2"></a><p class="title"><b>Example 15.1. Example File</b></p><pre class="programlisting">
+-rwxr-x--- Means:
+ ^^^ The owner (user) can read, write, execute
+ ^^^ the group can read and execute
+ ^^^ everyone else cannot do anything with it.
+</pre></div><p>
+<a class="indexterm" name="id2579184"></a>
+<a class="indexterm" name="id2579190"></a>
+<a class="indexterm" name="id2579197"></a>
+<a class="indexterm" name="id2579204"></a>
+ Additional possibilities in the [type] field are c = character device, b = block device, p = pipe device,
+ s = UNIX Domain Socket.
+ </p><p>
+<a class="indexterm" name="id2579217"></a>
+<a class="indexterm" name="id2579223"></a>
+<a class="indexterm" name="id2579230"></a>
+<a class="indexterm" name="id2579237"></a>
+<a class="indexterm" name="id2579244"></a>
+ The letters <code class="constant">rwxXst</code> set permissions for the user, group, and others as read (r), write (w),
+ execute (or access for directories) (x), execute only if the file is a directory or already has execute
+ permission for some user (X), set user (SUID) or group ID (SGID) on execution (s), sticky (t).
+ </p><p>
+<a class="indexterm" name="id2579262"></a>
+<a class="indexterm" name="id2579269"></a>
+<a class="indexterm" name="id2579276"></a>
+<a class="indexterm" name="id2579283"></a>
+ When the sticky bit is set on a directory, files in that directory may be unlinked (deleted) or renamed only by root or their owner.
+ Without the sticky bit, anyone able to write to the directory can delete or rename files. The sticky bit is commonly found on
+ directories, such as <code class="filename">/tmp</code>, that are world-writable.
+ </p><p>
+<a class="indexterm" name="id2579304"></a>
+<a class="indexterm" name="id2579311"></a>
+<a class="indexterm" name="id2579318"></a>
+<a class="indexterm" name="id2579325"></a>
+<a class="indexterm" name="id2579334"></a>
+ When the set user or group ID bit (s) is set on a directory, then all files created within it will be owned by the user and/or
+ group whose `set user or group' bit is set. This can be helpful in setting up directories for which it is desired that
+ all users who are in a group should be able to write to and read from a file, particularly when it is undesirable for that file
+ to be exclusively owned by a user whose primary group is not the group that all such users belong to.
+ </p><p>
+ When a directory is set <code class="constant">d-wx--x---</code>, the owner can read and create (write) files in it, but because
+ the (r) read flags are not set, files cannot be listed (seen) in the directory by anyone. The group can read files in the
+ directory but cannot create new files. If files in the directory are set to be readable and writable for the group, then
+ group members will be able to write to (or delete) them.
+ </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2579366"></a>Protecting Directories and Files from Deletion</h4></div></div></div><p>
+<a class="indexterm" name="id2579375"></a>
+<a class="indexterm" name="id2579382"></a>
+<a class="indexterm" name="id2579388"></a>
+<a class="indexterm" name="id2579395"></a>
+ People have asked on the Samba mailing list how is it possible to protect files or directories from deletion by users.
+ For example, Windows NT/2K/XP provides the capacity to set access controls on a directory into which people can
+ write files but not delete them. It is possible to set an ACL on a Windows file that permits the file to be written to
+ but not deleted. Such concepts are foreign to the UNIX operating system file space. Within the UNIX file system
+ anyone who has the ability to create a file can write to it. Anyone who has write permission on the
+ directory that contains a file and has write permission for it has the capability to delete it.
+ </p><p>
+<a class="indexterm" name="id2579417"></a>
+<a class="indexterm" name="id2579424"></a>
+<a class="indexterm" name="id2579431"></a>
+ For the record, in the UNIX environment the ability to delete a file is controlled by the permissions on
+ the directory that the file is in. In other words, a user can delete a file in a directory to which that
+ user has write access, even if that user does not own the file.
+ </p><p>
+<a class="indexterm" name="id2579446"></a>
+<a class="indexterm" name="id2579453"></a>
+<a class="indexterm" name="id2579460"></a>
+<a class="indexterm" name="id2579466"></a>
+ Of necessity, Samba is subject to the file system semantics of the host operating system. Samba is therefore
+ limited in the file system capabilities that can be made available through Windows ACLs, and therefore performs
+ a "best fit" translation to POSIX ACLs. Some UNIX file systems do, however support, a feature known
+ as extended attributes. Only the Windows concept of <span class="emphasis"><em>inheritance</em></span> is implemented by Samba through
+ the appropriate extended attribute.
+ </p><p>
+<a class="indexterm" name="id2579488"></a>
+<a class="indexterm" name="id2579495"></a>
+<a class="indexterm" name="id2579502"></a>
+<a class="indexterm" name="id2579508"></a>
+ The specific semantics of the extended attributes are not consistent across UNIX and UNIX-like systems such as Linux.
+ For example, it is possible on some implementations of the extended attributes to set a flag that prevents the directory
+ or file from being deleted. The extended attribute that may achieve this is called the <code class="constant">immutible</code> bit.
+ Unfortunately, the implementation of the immutible flag is NOT consistent with published documentation. For example, the
+ man page for the <span><strong class="command">chattr</strong></span> on SUSE Linux 9.2 says:
+</p><pre class="screen">
+A file with the i attribute cannot be modified: it cannot be deleted
+or renamed, no link can be created to this file and no data can be
+written to the file. Only the superuser or a process possessing the
+CAP_LINUX_IMMUTABLE capability can set or clear this attribute.
+</pre><p>
+ A simple test can be done to check if the immutible flag is supported on files in the file system of the Samba host
+ server.
+ </p><div class="procedure"><a name="id2579547"></a><p class="title"><b>Procedure 15.1. Test for File Immutibility Support</b></p><ol type="1"><li><p>
+ Create a file called <code class="filename">filename</code>.
+ </p></li><li><p>
+ Login as the <code class="constant">root</code> user, then set the immutibile flag on a test file as follows:
+</p><pre class="screen">
+<code class="prompt">root# </code> chatter +i `filename'
+</pre><p>
+ </p></li><li><p>
+ Login as the user who owns the file (not root) and attempt to remove the file as follows:
+</p><pre class="screen">
+mystic:/home/hannibal > rm filename
+</pre><p>
+ It will not be possible to delete the file if the immutible flag is correctly honored.
+ </p></li></ol></div><p>
+ On operating systems and file system types that support the immutible bit, it is possible to create directories
+ that cannot be deleted. Check the man page on your particular host system to determine whether or not
+ immutable directories are writable. If they are not, then the entire directory and its contents will effectively
+ be protected from writing (file creation also) and deletion.
+ </p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2579620"></a>Share Definition Access Controls</h2></div></div></div><p>
+ <a class="indexterm" name="id2579628"></a>
+ The following parameters in the <code class="filename">smb.conf</code> file sections define a share control or affect access controls.
+ Before using any of the following options, please refer to the man page for <code class="filename">smb.conf</code>.
+ </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2579653"></a>User- and Group-Based Controls</h3></div></div></div><p>
+ User- and group-based controls can prove quite useful. In some situations it is distinctly desirable to
+ force all file system operations as if a single user were doing so. The use of the
+ <a class="indexterm" name="id2579664"></a>force user and <a class="indexterm" name="id2579671"></a>force group behavior will achieve this.
+ In other situations it may be necessary to use a paranoia level of control to ensure that only particular
+ authorized persons will be able to access a share or its contents. Here the use of the
+ <a class="indexterm" name="id2579682"></a>valid users or the <a class="indexterm" name="id2579689"></a>invalid users parameter may be useful.
+ </p><p>
+ As always, it is highly advisable to use the easiest to maintain and the least ambiguous method for
+ controlling access. Remember, when you leave the scene, someone else will need to provide assistance, and
+ if he or she finds too great a mess or does not understand what you have done, there is risk of
+ Samba being removed and an alternative solution being adopted.
+ </p><p>
+ <a href="AccessControls.html#ugbc" title="Table 15.2. User- and Group-Based Controls">User and Group Based Controls</a> enumerates these controls.
+ </p><div class="table"><a name="ugbc"></a><p class="title"><b>Table 15.2. User- and Group-Based Controls</b></p><table summary="User- and Group-Based Controls" border="1"><colgroup><col align="left"><col align="justify"></colgroup><thead><tr><th align="center">Control Parameter</th><th align="center">Description, Action, Notes</th></tr></thead><tbody><tr><td align="left"><a class="indexterm" name="id2579771"></a>admin users</td><td align="justify"><p>
+ List of users who will be granted administrative privileges on the share.
+ They will do all file operations as the superuser (root).
+ Users in this list will be able to do anything they like on the share,
+ irrespective of file permissions.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579792"></a>force group</td><td align="justify"><p>
+ Specifies a UNIX group name that will be assigned as the default primary group
+ for all users connecting to this service.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579811"></a>force user</td><td align="justify"><p>
+ Specifies a UNIX username that will be assigned as the default user for all users connecting to this service.
+ This is useful for sharing files. Incorrect use can cause security problems.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579831"></a>guest ok</td><td align="justify"><p>
+ If this parameter is set for a service, then no password is required to connect to the service. Privileges will be
+ those of the guest account.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579850"></a>invalid users</td><td align="justify"><p>
+ List of users that should not be allowed to login to this service.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579868"></a>only user</td><td align="justify"><p>
+ Controls whether connections with usernames not in the user list will be allowed.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579887"></a>read list</td><td align="justify"><p>
+ List of users that are given read-only access to a service. Users in this list
+ will not be given write access, no matter what the read-only option is set to.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579906"></a>username</td><td align="justify"><p>
+ Refer to the <code class="filename">smb.conf</code> man page for more information; this is a complex and potentially misused parameter.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579931"></a>valid users</td><td align="justify"><p>
+ List of users that should be allowed to login to this service.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2579949"></a>write list</td><td align="justify"><p>
+ List of users that are given read-write access to a service.
+ </p></td></tr></tbody></table></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2579968"></a>File and Directory Permissions-Based Controls</h3></div></div></div><p>
+ Directory permission-based controls, if misused, can result in considerable difficulty in diagnosing the causes of
+ misconfiguration. Use them sparingly and carefully. By gradually introducing each, one at a time, undesirable side
+ effects may be detected. In the event of a problem, always comment all of them out and then gradually reintroduce
+ them in a controlled way.
+ </p><p>
+ Refer to <a href="AccessControls.html#fdpbc" title="Table 15.3. File and Directory Permission-Based Controls">File and Directory Permission Based Controls</a> for information
+ regarding the parameters that may be used to set file and directory permission-based access controls.
+ </p><div class="table"><a name="fdpbc"></a><p class="title"><b>Table 15.3. File and Directory Permission-Based Controls</b></p><table summary="File and Directory Permission-Based Controls" border="1"><colgroup><col align="left"><col align="justify"></colgroup><thead><tr><th align="center">Control Parameter</th><th align="center">Description, Action, Notes</th></tr></thead><tbody><tr><td align="left"><a class="indexterm" name="id2580047"></a>create mask</td><td align="justify"><p>
+ Refer to the <code class="filename">smb.conf</code> man page.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580070"></a>directory mask</td><td align="justify"><p>
+ The octal modes used when converting DOS modes to UNIX modes when creating UNIX directories.
+ See also directory security mask.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580088"></a>dos filemode</td><td align="justify"><p>
+ Enabling this parameter allows a user who has write access to the file to modify the permissions on it.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580107"></a>force create mode</td><td align="justify"><p>
+ This parameter specifies a set of UNIX-mode bit permissions that will always be set on a file created by Samba.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580126"></a>force directory mode</td><td align="justify"><p>
+ This parameter specifies a set of UNIX-mode bit permissions that will always be set on a directory created by Samba.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580146"></a>force directory security mode</td><td align="justify"><p>
+ Controls UNIX permission bits modified when a Windows NT client is manipulating UNIX permissions on a directory.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580165"></a>force security mode</td><td align="justify"><p>
+ Controls UNIX permission bits modified when a Windows NT client manipulates UNIX permissions.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580184"></a>hide unreadable</td><td align="justify"><p>
+ Prevents clients from seeing the existence of files that cannot be read.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580203"></a>hide unwriteable files</td><td align="justify"><p>
+ Prevents clients from seeing the existence of files that cannot be written to. Unwritable directories are shown as usual.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580222"></a>nt acl support</td><td align="justify"><p>
+ This parameter controls whether smbd will attempt to map UNIX permissions into Windows NT ACLs.
+ </p></td></tr><tr><td align="left"><a class="indexterm" name="id2580241"></a>security mask</td><td align="justify"><p>
+ Controls UNIX permission bits modified when a Windows NT client is manipulating the UNIX permissions on a file.
+ </p></td></tr></tbody></table></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2580261"></a>Miscellaneous Controls</h3></div></div></div><p>
+ The parameter documented in <a href="AccessControls.html#mcoc" title="Table 15.4. Other Controls">Other Controls</a> are often used by administrators
+ in ways that create inadvertent barriers to file access. Such are the consequences of not understanding the
+ full implications of <code class="filename">smb.conf</code> file settings.
+ </p><div class="table"><a name="mcoc"></a><p class="title"><b>Table 15.4. Other Controls</b></p><table summary="Other Controls" border="1"><colgroup><col align="justify"><col align="justify"></colgroup><thead><tr><th align="center">Control Parameter</th><th align="center">Description, Action, Notes</th></tr></thead><tbody><tr><td align="justify">
+ <a class="indexterm" name="id2580339"></a>case sensitive,
+ <a class="indexterm" name="id2580346"></a>default case,
+ <a class="indexterm" name="id2580354"></a>short preserve case
+ </td><td align="justify"><p>
+ This means that all file name lookup will be done in a case-sensitive manner.
+ Files will be created with the precise file name Samba received from the MS Windows client.
+ </p></td></tr><tr><td align="justify"><a class="indexterm" name="id2580374"></a>csc policy</td><td align="justify"><p>
+ Client-side caching policy parallels MS Windows client-side file caching capabilities.
+ </p></td></tr><tr><td align="justify"><a class="indexterm" name="id2580392"></a>dont descend</td><td align="justify"><p>
+ Allows specifying a comma-delimited list of directories that the server should always show as empty.
+ </p></td></tr><tr><td align="justify"><a class="indexterm" name="id2580411"></a>dos filetime resolution</td><td align="justify"><p>
+ This option is mainly used as a compatibility option for Visual C++ when used against Samba shares.
+ </p></td></tr><tr><td align="justify"><a class="indexterm" name="id2580430"></a>dos filetimes</td><td align="justify"><p>
+ DOS and Windows allow users to change file timestamps if they can write to the file. POSIX semantics prevent this.
+ This option allows DOS and Windows behavior.
+ </p></td></tr><tr><td align="justify"><a class="indexterm" name="id2580450"></a>fake oplocks</td><td align="justify"><p>
+ Oplocks are the way that SMB clients get permission from a server to locally cache file operations. If a server grants an
+ oplock, the client is free to assume that it is the only one accessing the file, and it will aggressively cache file data.
+ </p></td></tr><tr><td align="justify">
+ <a class="indexterm" name="id2580472"></a>hide dot files,
+ <a class="indexterm" name="id2580480"></a>hide files,
+ <a class="indexterm" name="id2580487"></a>veto files
+ </td><td align="justify"><p>
+ Note: MS Windows Explorer allows override of files marked as hidden so they will still be visible.
+ </p></td></tr><tr><td align="justify"><a class="indexterm" name="id2580506"></a>read only</td><td align="justify"><p>
+ If this parameter is yes, then users of a service may not create or modify files in the service's directory.
+ </p></td></tr><tr><td align="justify"><a class="indexterm" name="id2580524"></a>veto files</td><td align="justify"><p>
+ List of files and directories that are neither visible nor accessible.
+ </p></td></tr></tbody></table></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2580545"></a>Access Controls on Shares</h2></div></div></div><p>
+<a class="indexterm" name="id2580553"></a>
+<a class="indexterm" name="id2580560"></a>
+<a class="indexterm" name="id2580567"></a>
+<a class="indexterm" name="id2580574"></a>
+ <a class="indexterm" name="id2580581"></a>
+ This section deals with how to configure Samba per-share access control restrictions.
+ By default, Samba sets no restrictions on the share itself. Restrictions on the share itself
+ can be set on MS Windows NT4/200x/XP shares. This can be an effective way to limit who can
+ connect to a share. In the absence of specific restrictions, the default setting is to allow
+ the global user <code class="constant">Everyone - Full Control</code> (full control, change and read).
+ </p><p>
+<a class="indexterm" name="id2580604"></a>
+<a class="indexterm" name="id2580611"></a>
+<a class="indexterm" name="id2580618"></a>
+ At this time Samba does not provide a tool for configuring access control settings on the share
+ itself the only way to create those settings is to use either the NT4 Server Manager or the Windows 200x
+ Microsoft Management Console (MMC) for Computer Management. There are currently no plans to provide
+ this capability in the Samba command-line tool set.
+ </p><p>
+<a class="indexterm" name="id2580634"></a>
+<a class="indexterm" name="id2580641"></a>
+<a class="indexterm" name="id2580648"></a>
+<a class="indexterm" name="id2580655"></a>
+ Samba stores the per-share access control settings in a file called <code class="filename">share_info.tdb</code>.
+ The location of this file on your system will depend on how Samba was compiled. The default location
+ for Samba's tdb files is under <code class="filename">/usr/local/samba/var</code>. If the <code class="filename">tdbdump</code>
+ utility has been compiled and installed on your system, then you can examine the contents of this file
+ by executing <span><strong class="command">tdbdump share_info.tdb</strong></span> in the directory containing the tdb files.
+ </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2580693"></a>Share Permissions Management</h3></div></div></div><p>
+ The best tool for share permissions management is platform-dependent. Choose the best tool for your environment.
+ </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2580705"></a>Windows NT4 Workstation/Server</h4></div></div></div><p>
+<a class="indexterm" name="id2580713"></a>
+<a class="indexterm" name="id2580720"></a>
+<a class="indexterm" name="id2580727"></a>
+<a class="indexterm" name="id2580734"></a>
+ The tool you need to manage share permissions on a Samba server from a Windows NT4 Workstation or Server
+ is the NT Server Manager. Server Manager is shipped with Windows NT4 Server products but not with Windows
+ NT4 Workstation. You can obtain the NT Server Manager for MS Windows NT4 Workstation from the Microsoft
+ web site <a href="http://support.microsoft.com/default.aspx?scid=kb;en-us;173673" target="_top">support</a> section.
+ </p><div class="procedure"><a name="id2580754"></a><p class="title"><b>Procedure 15.2. Instructions</b></p><ol type="1"><li><p>
+ Launch the <span class="application">NT4 Server Manager</span> and click on the Samba server you want to
+ administer. From the menu select <span class="guimenu">Computer</span>, then click on
+ <span class="guimenuitem">Shared Directories</span>.
+ </p></li><li><p>
+ Click on the share that you wish to manage and click the <span class="guilabel">Properties</span> tab, then click
+ the <span class="guilabel">Permissions</span> tab. Now you can add or change access control settings as you wish.
+ </p></li></ol></div></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2580810"></a>Windows 200x/XP</h4></div></div></div><p>
+<a class="indexterm" name="id2580818"></a>
+<a class="indexterm" name="id2580825"></a>
+<a class="indexterm" name="id2580832"></a>
+<a class="indexterm" name="id2580838"></a>
+ On <span class="application">MS Windows NT4/200x/XP</span> system, ACLs on the share itself are set using native
+ tools, usually from File Manager. For example, in Windows 200x, right-click on the shared folder,
+ then select <span class="guimenuitem">Sharing</span>, then click on <span class="guilabel">Permissions</span>. The default
+ Windows NT4/200x permission allows "Everyone" full control on the share.
+ </p><p>
+<a class="indexterm" name="id2580871"></a>
+<a class="indexterm" name="id2580878"></a>
+<a class="indexterm" name="id2580885"></a>
+ MS Windows 200x and later versions come with a tool called the <span class="application">Computer Management</span>
+ snap-in for the MMC. This tool is located by clicking on <span class="guimenu">Control Panel ->
+ Administrative Tools -> Computer Management</span>.
+ </p><div class="procedure"><a name="id2580909"></a><p class="title"><b>Procedure 15.3. Instructions</b></p><ol type="1"><li><p>
+ After launching the MMC with the Computer Management snap-in, click the menu item <span class="guimenuitem">Action</span>
+ and select <span class="guilabel">Connect to another computer</span>. If you are not logged onto a domain you will be prompted
+ to enter a domain login user identifier and a password. This will authenticate you to the domain.
+ If you are already logged in with administrative privilege, this step is not offered.
+ </p></li><li><p>
+ If the Samba server is not shown in the <span class="guilabel">Select Computer</span> box, type in the name of the target
+ Samba server in the field <span class="guilabel">Name:</span>. Now click the on <span class="guibutton">[+]</span> next to
+ <span class="guilabel">System Tools</span>, then on the <span class="guibutton">[+]</span> next to
+ <span class="guilabel">Shared Folders</span> in the left panel.
+ </p></li><li><p>
+<a class="indexterm" name="id2580990"></a>
+ In the right panel, double-click on the share on which you wish to set access control permissions.
+ Then click the tab <span class="guilabel">Share Permissions</span>. It is now possible to add access control entities
+ to the shared folder. Remember to set what type of access (full control, change, read) you
+ wish to assign for each entry.
+ </p></li></ol></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>
+ Be careful. If you take away all permissions from the <code class="constant">Everyone</code> user without removing
+ this user, effectively no user will be able to access the share. This is a result of what is known as
+ ACL precedence. Everyone with <span class="emphasis"><em>no access</em></span> means that <code class="constant">MaryK</code> who is
+ part of the group <code class="constant">Everyone</code> will have no access even if she is given explicit full
+ control access.
+ </p></div></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2581040"></a>MS Windows Access Control Lists and UNIX Interoperability</h2></div></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2581046"></a>Managing UNIX Permissions Using NT Security Dialogs</h3></div></div></div><p>
+ <a class="indexterm" name="id2581055"></a>
+ Windows NT clients can use their native security settings dialog box to view and modify the
+ underlying UNIX permissions.
+ </p><p>
+ This ability is careful not to compromise the security of the UNIX host on which Samba is running and
+ still obeys all the file permission rules that a Samba administrator can set.
+ </p><p>
+ Samba does not attempt to go beyond POSIX ACLs, so the various finer-grained access control
+ options provided in Windows are actually ignored.
+ </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
+ All access to UNIX/Linux system files via Samba is controlled by the operating system file access controls.
+ When trying to figure out file access problems, it is vitally important to find the identity of the Windows
+ user as it is presented by Samba at the point of file access. This can best be determined from the
+ Samba log files.
+ </p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2581093"></a>Viewing File Security on a Samba Share</h3></div></div></div><p>
+ From an NT4/2000/XP client, right-click on any file or directory in a Samba-mounted drive letter
+ or UNC path. When the menu pops up, click on the <span class="guilabel">Properties</span> entry at the bottom
+ of the menu. This brings up the file <code class="constant">Properties</code> dialog box. Click on the
+ <span class="guilabel">Security</span> tab and you will see three buttons: <span class="guibutton">Permissions</span>,
+ <span class="guibutton">Auditing</span>, and <span class="guibutton">Ownership</span>. The <span class="guibutton">Auditing</span>
+ 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 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
+ nonfunctional with a Samba share at this time, because the only useful button, the <span class="guibutton">Add</span>
+ button, will not currently allow a list of users to be seen.
+ </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2581164"></a>Viewing File Ownership</h3></div></div></div><p>
+ Clicking on the <span class="guibutton">Ownership</span> button brings up a dialog box telling you who owns
+ the given file. The owner name will be displayed like this:
+ </p><pre class="screen">
+ <code class="constant">SERVER\user (Long name)</code>
+ </pre><p>
+ <em class="replaceable"><code>SERVER</code></em> is the NetBIOS name of the Samba server, <em class="replaceable"><code>user</code></em>
+ is the username of the UNIX user who owns the file, and <em class="replaceable"><code>(Long name)</code></em> is the
+ descriptive string identifying the user (normally found in the GECOS field of the UNIX password database).
+ Click on the <span class="guibutton">Close</span> button to remove this dialog.
+ </p><p>
+ If the parameter <a class="indexterm" name="id2581215"></a>nt acl support is set to <code class="constant">false</code>,
+ the file owner will be shown as the NT user <span class="emphasis"><em>Everyone</em></span>.
+ </p><p>
+<a class="indexterm" name="id2581233"></a>
+ The <span class="guibutton">Take Ownership</span> button will not allow you to change the ownership of this file to
+ yourself (clicking it will display a dialog box complaining that the user as whom 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 <span class="emphasis"><em>root</em></span> user. Because 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>
+<a class="indexterm" name="id2581262"></a>
+<a class="indexterm" name="id2581269"></a>
+<a class="indexterm" name="id2581276"></a>
+ There is an NT <span><strong class="command">chown</strong></span> command that will work with Samba and allow a user with administrator
+ privilege connected to a Samba server as root to change the ownership of files on both a local NTFS file system
+ or remote mounted NTFS or Samba drive. This is available as part of the <span class="application">Seclib</span> NT
+ security library written by Jeremy Allison of the Samba Team and is downloadable from the main Samba FTP site.
+ </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2581303"></a>Viewing File or Directory Permissions</h3></div></div></div><p>
+ The third button is the <span class="guibutton">Permissions</span> button. Clicking on it brings up a dialog box
+ that shows both the permissions and the UNIX owner of the file or directory. The owner is displayed like this:
+ </p><p><span><strong class="command"><em class="replaceable"><code>SERVER</code></em>\
+ <em class="replaceable"><code>user</code></em>
+ <em class="replaceable"><code>(Long name)</code></em></strong></span></p><p><em class="replaceable"><code>SERVER</code></em> is the NetBIOS name of the Samba server,
+ <em class="replaceable"><code>user</code></em> is the username of the UNIX user who owns the file, and
+ <em class="replaceable"><code>(Long name)</code></em> is the descriptive string identifying the user (normally found in the
+ GECOS field of the UNIX password database).</p><p>
+ If the parameter <a class="indexterm" name="id2581356"></a>nt acl support is set to <code class="constant">false</code>,
+ the file owner will be shown as the NT user <code class="constant">Everyone</code>, and the permissions will be
+ shown as NT <span class="emphasis"><em>Full Control</em></span>.
+ </p><p>
+ The permissions field is displayed differently for files and directories. Both are discussed next.
+ </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2581382"></a>File Permissions</h4></div></div></div><p>
+ The standard UNIX user/group/world triplet and the corresponding <code class="constant">read, write,
+ execute</code> permissions triplets are mapped by Samba into a three-element NT ACL with the
+ “<span class="quote">r</span>”, “<span class="quote">w</span>”, and “<span class="quote">x</span>” bits mapped into the corresponding NT
+ permissions. The UNIX world permissions are mapped into the global NT group <code class="constant">Everyone</code>, followed
+ by the list of permissions allowed for the UNIX world. The UNIX owner and group permissions are displayed as an NT
+ <span class="guiicon">user</span> icon and an NT <span class="guiicon">local group</span> icon, respectively, followed by the list
+ of permissions allowed for the UNIX user and group.
+ </p><p>
+ Because many UNIX permission sets do not map into common NT names such as <code class="constant">read</code>,
+ <code class="constant">change</code>, or <code class="constant">full control</code>, usually the permissions will be prefixed
+ by the words <code class="constant">Special Access</code> 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 <span class="emphasis"><em>no permissions</em></span> to be seen and modified, Samba then overloads the NT
+ <code class="constant">Take Ownership</code> ACL attribute (which has no meaning in UNIX) and reports a component with
+ no permissions as having the NT <span><strong class="command">O</strong></span> bit set. This was chosen, of course, to make it look
+ like a zero, meaning zero permissions. More details on the decision behind this action are given below.
+ </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2581476"></a>Directory Permissions</h4></div></div></div><p>
+ Directories on an NT NTFS file system have two different sets of permissions. The first set is the ACL set on the
+ directory itself, which is usually displayed in the first set of parentheses in the normal <code class="constant">RW</code>
+ 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 <code class="constant">
+ inherited</code> permissions that any file created within this directory would inherit.
+ </p><p>
+ Samba synthesizes 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="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2581514"></a>Modifying File or Directory Permissions</h3></div></div></div><p>
+ Modifying file and directory permissions is as simple as changing the displayed permissions in the dialog box
+ and clicking on <span class="guibutton">OK</span>. 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 also need to
+ be taken into account.
+ </p><p>
+ If the parameter <a class="indexterm" name="id2581537"></a>nt acl support is set to <code class="constant">false</code>, any attempt to
+ set security permissions will fail with an <span class="errorname">"Access Denied" </span> message.
+ </p><p>
+ The first thing to note is that the <span class="guibutton">Add</span> button will not return a list of users in Samba
+ (it will give an error message saying <span class="errorname">"The remote procedure call failed and did not
+ execute"</span>). This means that you can only manipulate the current user/group/world permissions listed
+ in the dialog box. This actually works quite well because these are the only permissions that UNIX actually
+ has.
+ </p><p>
+ If a permission triplet (either user, group, or world) is removed from the list of permissions in the NT
+ dialog box, then when the <span class="guibutton">OK</span> button is pressed, it will be applied as <span class="emphasis"><em>no
+ permissions</em></span> on the UNIX side. If you view the permissions again, the <span class="emphasis"><em>no
+ permissions</em></span> entry will appear as the NT <span><strong class="command">O</strong></span> flag, as described above. This allows
+ you to add permissions back to a file or directory once you have removed them from a triplet component.
+ </p><p>
+ Because UNIX supports only the “<span class="quote">r</span>”, “<span class="quote">w</span>”, and “<span class="quote">x</span>” bits of an NT ACL, if
+ other NT security attributes such as <code class="constant">Delete Access</code> are selected, 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
+ <span class="guilabel">Replace permissions on existing files</span> checkbox in the NT dialog before clicking on
+ <span class="guibutton">OK</span>.
+ </p><p>
+ If you wish to remove all permissions from a user/group/world component, you may either highlight the
+ component and click on the <span class="guibutton">Remove</span> button or set the component to only have the special
+ <code class="constant">Take Ownership</code> permission (displayed as <span><strong class="command">O</strong></span>) highlighted.
+ </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2581668"></a>Interaction with the Standard Samba “<span class="quote">create mask</span>” Parameters</h3></div></div></div><p>There are four parameters that control interaction with the standard Samba <em class="parameter"><code>create mask</code></em> parameters:
+
+
+ </p><div class="itemizedlist"><ul type="disc"><li><p><a class="indexterm" name="id2581691"></a>security mask</p></li><li><p><a class="indexterm" name="id2581702"></a>force security mode</p></li><li><p><a class="indexterm" name="id2581712"></a>directory security mask</p></li><li><p><a class="indexterm" name="id2581723"></a>force directory security mode</p></li></ul></div><p>
+
+ </p><p>
+ When a user clicks on <span class="guibutton">OK</span> to apply the
+ permissions, Samba maps the given permissions into a user/group/world
+ r/w/x triplet set, and then checks the changed permissions for a
+ file against the bits set in the
+ <a class="indexterm" name="id2581746"></a>security mask parameter. Any bits that
+ were changed that are not set to <span class="emphasis"><em>1</em></span> in this parameter are left alone
+ in the file permissions.</p><p>
+ Essentially, zero bits in the <a class="indexterm" name="id2581762"></a>security mask
+ may be treated as a set of bits the user is <span class="emphasis"><em>not</em></span>
+ allowed to change, and one bits are those the user is allowed to change.
+ </p><p>
+ If not explicitly set, this parameter defaults to the same value as
+ the <a class="indexterm" name="id2581779"></a>create mask parameter. 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 class="indexterm" name="id2581793"></a>force security mode parameter. Any bits
+ that were changed that correspond to bits set to <span class="emphasis"><em>1</em></span> in this parameter
+ are forced to be set.</p><p>
+ Essentially, bits set in the <em class="parameter"><code>force security mode</code></em> parameter
+ may be treated as a set of bits that, when modifying security on a file, the user
+ has always set to be <span class="emphasis"><em>on</em></span>.</p><p>
+ If not explicitly set, this parameter defaults to the same value
+ as the <a class="indexterm" name="id2581826"></a>force create mode parameter.
+ To allow a user to modify all the user/group/world permissions on a file
+ with no restrictions, set this parameter to 000. The
+ <a class="indexterm" name="id2581835"></a>security mask and <em class="parameter"><code>force
+ security mode</code></em> parameters are applied to the change
+ request in that order.</p><p>
+ For a directory, Samba performs the same operations as
+ described above for a file except it uses the parameter <em class="parameter"><code>
+ directory security mask</code></em> instead of <em class="parameter"><code>security
+ mask</code></em>, and <em class="parameter"><code>force directory security mode
+ </code></em> parameter instead of <em class="parameter"><code>force security mode
+ </code></em>.</p><p>
+ The <a class="indexterm" name="id2581884"></a>directory security mask parameter
+ by default is set to the same value as the <em class="parameter"><code>directory mask
+ </code></em> parameter and the <em class="parameter"><code>force directory security
+ mode</code></em> parameter by default is set to the same value as
+ the <a class="indexterm" name="id2581906"></a>force directory mode parameter.
+ In this way Samba enforces the permission restrictions that
+ an administrator can set on a Samba share, while 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
+ does not force any particular bits to be set <span class="emphasis"><em>on</em></span>,
+ then set the following parameters in the <code class="filename">smb.conf</code> file in that
+ share-specific section:
+ </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2581943"></a><em class="parameter"><code>security mask = 0777</code></em></td></tr><tr><td><a class="indexterm" name="id2581956"></a><em class="parameter"><code>force security mode = 0</code></em></td></tr><tr><td><a class="indexterm" name="id2581968"></a><em class="parameter"><code>directory security mask = 0777</code></em></td></tr><tr><td><a class="indexterm" name="id2581982"></a><em class="parameter"><code>force directory security mode = 0</code></em></td></tr></table></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2581996"></a>Interaction with the Standard Samba File Attribute Mapping</h3></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
+ Samba maps some of the DOS attribute bits (such as “<span class="quote">read-only</span>”)
+ 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></div><p>
+ If a file has no UNIX read access for the owner, it will show up
+ as “<span class="quote">read-only</span>” in the standard file attributes tabbed dialog.
+ Unfortunately, this dialog is the same one that contains the security information
+ in another tab.
+ </p><p>
+ What this can mean is that if the owner changes the permissions
+ to allow himself or herself read access using the security dialog, clicks on
+ <span class="guibutton">OK</span> to get back to the standard attributes tab
+ dialog, and clicks on <span class="guibutton">OK</span> 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 on <span class="guibutton">OK</span> to get back to the
+ attributes dialog, you should always press <span class="guibutton">Cancel</span>
+ rather than <span class="guibutton">OK</span> to ensure that your changes
+ are not overridden.
+ </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2582069"></a>Windows NT/200X ACLs and POSIX ACLs Limitations</h3></div></div></div><p>
+ Windows administrators are familiar with simple ACL controls, and they typically
+ consider that UNIX user/group/other (ugo) permissions are inadequate and not
+ sufficiently fine-grained.
+ </p><p>
+ Competing SMB implementations differ in how they handle Windows ACLs. Samba handles
+ Windows ACLs from the perspective of UNIX file system administration and thus adopts
+ the limitations of POSIX ACLs. Therefore, where POSIX ACLs lack a capability of the
+ Windows NT/200X ACLs, the POSIX semantics and limitations are imposed on the Windows
+ administrator.
+ </p><p>
+ POSIX ACLs present an interesting challenge to the UNIX administrator and therefore
+ force a compromise to be applied to Windows ACLs administration. POSIX ACLs are not
+ covered by an official standard; rather, the latest standard is a draft standard
+ 1003.1e revision 17. This is the POSIX document on which the Samba implementation has
+ been implemented.
+ </p><p>
+ UNIX vendors differ in the manner in which POSIX ACLs are implemented. There are a
+ number of Linux file systems that support ACLs. Samba has to provide a way to make
+ transparent all the differences between the various implementations of POSIX ACLs.
+ The pressure for ACLs support in Samba has noticeably increased the pressure to
+ standardize ACLs support in the UNIX world.
+ </p><p>
+ Samba has to deal with the complicated matter of handling the challenge of the Windows
+ ACL that implements <span class="emphasis"><em>inheritance</em></span>, a concept not anticipated by POSIX
+ ACLs as implemented in UNIX file systems. Samba provides support for <span class="emphasis"><em>masks</em></span>
+ that permit normal ugo and ACLs functionality to be overrided. This further complicates
+ the way in which Windows ACLs must be implemented.
+ </p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2582127"></a>UNIX POSIX ACL Overview</h4></div></div></div><p>
+ In examining POSIX ACLs we must consider the manner in which they operate for
+ both files and directories. File ACLs have the following significance:
+</p><pre class="screen">
+# file: testfile <- the file name
+# owner: jeremy <-- the file owner
+# group: users <-- the POSIX group owner
+user::rwx <-- perms for the file owner (user)
+user:tpot:r-x <-- perms for the additional user `tpot'
+group::r-- <-- perms for the file group owner (group)
+group:engrs:r-- <-- perms for the additonal group `engineers'
+mask:rwx <-- the mask that is `ANDed' with groups
+other::--- <-- perms applied to everyone else (other)
+</pre><p>
+ Directory ACLs have the following signficance:
+</p><pre class="screen">
+# file: testdir <-- the directory name
+# owner: jeremy <-- the directory owner
+# group: jeremy <-- the POSIX group owner
+user::rwx <-- directory perms for owner (user)
+group::rwx <-- directory perms for owning group (group)
+mask::rwx <-- the mask that is `ANDed' with group perms
+other:r-x <-- perms applied to everyone else (other)
+default:user::rwx <-- inherited owner perms
+default:user:tpot:rwx <-- inherited extra perms for user `tpot'
+default:group::r-x <-- inherited group perms
+default:mask:rwx <-- inherited default mask
+default:other:--- <-- inherited permissions for everyone (other)
+</pre><p>
+ </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2582188"></a>Mapping of Windows File ACLs to UNIX POSIX ACLs</h4></div></div></div><p>
+ Microsoft Windows NT4/200X ACLs must of necessity be mapped to POSIX ACLs.
+ The mappings for file permissions are shown in <a href="AccessControls.html#fdsacls" title="Table 15.5. How Windows File ACLs Map to UNIX POSIX File ACLs">How
+ Windows File ACLs Map to UNIX POSIX File ACLs</a>.
+ The # character means this flag is set only when the Windows administrator
+ sets the <code class="constant">Full Control</code> flag on the file.
+ </p><div class="table"><a name="fdsacls"></a><p class="title"><b>Table 15.5. How Windows File ACLs Map to UNIX POSIX File ACLs</b></p><table summary="How Windows File ACLs Map to UNIX POSIX File ACLs" border="1"><colgroup><col align="left"><col align="center"></colgroup><thead><tr><th align="left">Windows ACE</th><th align="center">File Attribute Flag</th></tr></thead><tbody><tr><td align="left"><p>Full Control</p></td><td align="center"><p>#</p></td></tr><tr><td align="left"><p>Traverse Folder/Execute File</p></td><td align="center"><p>x</p></td></tr><tr><td align="left"><p>List Folder/Read Data</p></td><td align="center"><p>r</p></td></tr><tr><td align="left"><p>Read Attributes</p></td><td align="center"><p>r</p></td></tr><tr><td align="left"><p>Read Extended Attribures</p></td><td align="center"><p>r</p></td></tr><tr><td align="left"><p>Create Files/Write Data</p></td><td align="center"><p>w</p></td></tr><tr><td align="left"><p>Create Folders/Append Data</p></td><td align="center"><p>w</p></td></tr><tr><td align="left"><p>Write Attributes</p></td><td align="center"><p>w</p></td></tr><tr><td align="left"><p>Write Extended Attributes</p></td><td align="center"><p>w</p></td></tr><tr><td align="left"><p>Delete Subfolders and Files</p></td><td align="center"><p>w</p></td></tr><tr><td align="left"><p>Delete</p></td><td align="center"><p>#</p></td></tr><tr><td align="left"><p>Read Permissions</p></td><td align="center"><p>all</p></td></tr><tr><td align="left"><p>Change Permissions</p></td><td align="center"><p>#</p></td></tr><tr><td align="left"><p>Take Ownership</p></td><td align="center"><p>#</p></td></tr></tbody></table></div><p>
+ As can be seen from the mapping table, there is no one-to-one mapping capability, and therefore
+ Samba must make a logical mapping that will permit Windows to operate more-or-less the way
+ that is intended by the administrator.
+ </p><p>
+ In general the mapping of UNIX POSIX user/group/other permissions will be mapped to
+ Windows ACLs. This has precedence over the creation of POSIX ACLs. POSIX ACLs are necessary
+ to establish access controls for users and groups other than the user and group that
+ own the file or directory.
+ </p><p>
+ The UNIX administrator can set any directory permission from within the UNIX environment.
+ The Windows administrator is more restricted in that it is not possible from within
+ Windows Explorer to remove read permission for the file owner.
+ </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2582457"></a>Mapping of Windows Directory ACLs to UNIX POSIX ACLs</h4></div></div></div><p>
+ Interesting things happen in the mapping of UNIX POSIX directory permissions and
+ UNIX POSIX ACLs to Windows ACEs (Access Control Entries, the discrete components of
+ an ACL) are mapped to Windows directory ACLs.
+ </p><p>
+ Directory permissions function in much the same way as shown for file permissions, but
+ there are some notable exceptions and a few peculiarities that the astute administrator
+ will want to take into account in the setting up of directory permissions.
+ </p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2582481"></a>Common Errors</h2></div></div></div><p>
+File, directory, and share access problems are common topics on the mailing list. The following
+are examples recently taken from the mailing list.
+</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2582492"></a>Users Cannot Write to a Public Share</h3></div></div></div><p>
+ “<span class="quote">
+ We are facing some troubles with file/directory permissions. I can log on the domain as admin user (root),
+ and there's a public share on which everyone needs to have permission to create/modify files, but only
+ root can change the file, no one else can. We need to constantly go to the server to
+ <strong class="userinput"><code>chgrp -R users *</code></strong> and <strong class="userinput"><code>chown -R nobody *</code></strong> to allow
+ other users to change the file.
+ </span>”
+ </p><p>
+ There are many ways to solve this problem, and here are a few hints:
+ </p><div class="procedure"><ol type="1"><li><p>
+ Go to the top of the directory that is shared.
+ </p></li><li><p>
+ Set the ownership to whatever public user and group you want
+</p><pre class="screen">
+<code class="prompt">$ </code>find `directory_name' -type d -exec chown user:group {}\;
+<code class="prompt">$ </code>find `directory_name' -type d -exec chmod 1775 {}\;
+<code class="prompt">$ </code>find `directory_name' -type f -exec chmod 0775 {}\;
+<code class="prompt">$ </code>find `directory_name' -type f -exec chown user:group {}\;
+</pre><p>
+ </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
+ The above will set the <code class="constant">sticky bit</code> on all directories. Read your
+ UNIX/Linux man page on what that does. It causes the OS to assign to all files
+ created in the directories the ownership of the directory.
+ </p></div></li><li><p>
+ Directory is <em class="replaceable"><code>/foodbar</code></em>:
+</p><pre class="screen">
+<code class="prompt">$ </code><strong class="userinput"><code>chown jack:engr /foodbar</code></strong>
+</pre><p>
+ </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>This is the same as doing:</p><pre class="screen">
+<code class="prompt">$ </code><strong class="userinput"><code>chown jack /foodbar</code></strong>
+<code class="prompt">$ </code><strong class="userinput"><code>chgrp engr /foodbar</code></strong>
+</pre></div></li><li><p>Now type:
+
+</p><pre class="screen">
+<code class="prompt">$ </code><strong class="userinput"><code>chmod 6775 /foodbar</code></strong>
+<code class="prompt">$ </code><strong class="userinput"><code>ls -al /foodbar/..</code></strong>
+</pre><p>
+
+ </p><p>You should see:
+</p><pre class="screen">
+drwsrwsr-x 2 jack engr 48 2003-02-04 09:55 foodbar
+</pre><p>
+ </p></li><li><p>Now type:
+</p><pre class="screen">
+<code class="prompt">$ </code><strong class="userinput"><code>su - jill</code></strong>
+<code class="prompt">$ </code><strong class="userinput"><code>cd /foodbar</code></strong>
+<code class="prompt">$ </code><strong class="userinput"><code>touch Afile</code></strong>
+<code class="prompt">$ </code><strong class="userinput"><code>ls -al</code></strong>
+</pre><p>
+ </p><p>
+ You should see that the file <code class="filename">Afile</code> created by Jill will have ownership
+ and permissions of Jack, as follows:
+</p><pre class="screen">
+-rw-r--r-- 1 jack engr 0 2003-02-04 09:57 Afile
+</pre><p>
+ </p></li><li><p>
+ Now in your <code class="filename">smb.conf</code> for the share add:
+ </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2582791"></a><em class="parameter"><code>force create mode = 0775</code></em></td></tr><tr><td><a class="indexterm" name="id2582804"></a><em class="parameter"><code>force directory mode = 6775</code></em></td></tr></table><p>
+ </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
+ These procedures are needed only if your users are not members of the group
+ you have used that is, if within the OS they do not have write permission on the directory.
+ </p></div><p>
+ An alternative is to set in the <code class="filename">smb.conf</code> entry for the share:
+ </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2582844"></a><em class="parameter"><code>force user = jack</code></em></td></tr><tr><td><a class="indexterm" name="id2582857"></a><em class="parameter"><code>force group = engr</code></em></td></tr></table><p>
+ </p></li></ol></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2582874"></a>File Operations Done as <span class="emphasis"><em>root</em></span> with <span class="emphasis"><em>force user</em></span> Set</h3></div></div></div><p>
+ When you have a user in <a class="indexterm" name="id2582890"></a>admin users, Samba will always do file operations for
+ this user as <span class="emphasis"><em>root</em></span>, even if <a class="indexterm" name="id2582901"></a>force user has been set.
+ </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2582911"></a>MS Word with Samba Changes Owner of File</h3></div></div></div><p>
+ <span class="emphasis"><em>Question:</em></span> “<span class="quote">When user B saves a word document that is owned by user A,
+ the updated file is now owned by user B. Why is Samba doing this? How do I fix this?</span>”
+ </p><p>
+ <span class="emphasis"><em>Answer:</em></span> Word does the following when you modify/change a Word document: MS Word creates a new document with
+ a temporary name. Word then closes the old document and deletes it, then renames the new document to the original document name.
+ There is no mechanism by which Samba can in any way know that the new document really should be owned by the owners
+ of the original file. Samba has no way of knowing that the file will be renamed by MS Word. As far as Samba is able
+ to tell, the file that gets created is a new file, not one that the application (Word) is updating.
+ </p><p>
+ There is a workaround to solve the permissions problem. It involves understanding how you can manage file
+ system behavior from within the <code class="filename">smb.conf</code> file, as well as understanding how UNIX file systems work. Set on the directory
+ in which you are changing Word documents: <span><strong class="command">chmod g+s `directory_name'.</strong></span> This ensures that all files will
+ be created with the group that owns the directory. In <code class="filename">smb.conf</code> share declaration section set:
+ </p><p>
+ </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2582981"></a><em class="parameter"><code>force create mode = 0660</code></em></td></tr><tr><td><a class="indexterm" name="id2582994"></a><em class="parameter"><code>force directory mode = 0770</code></em></td></tr></table><p>
+ </p><p>
+ These two settings will ensure that all directories and files that get created in the share will be readable/writable by the
+ owner and group set on the directory itself.
+ </p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="rights.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="optional.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="locking.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 14. User Rights and Privileges </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 16. File and Record Locking</td></tr></table></div></body></html>
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