diff options
Diffstat (limited to 'docs/Samba3-HOWTO/TOSHARG-AccessControls.xml')
| -rw-r--r-- | docs/Samba3-HOWTO/TOSHARG-AccessControls.xml | 839 |
1 files changed, 441 insertions, 398 deletions
diff --git a/docs/Samba3-HOWTO/TOSHARG-AccessControls.xml b/docs/Samba3-HOWTO/TOSHARG-AccessControls.xml index 973f390238..51f08c2f57 100644 --- a/docs/Samba3-HOWTO/TOSHARG-AccessControls.xml +++ b/docs/Samba3-HOWTO/TOSHARG-AccessControls.xml @@ -8,11 +8,11 @@ <author>&person.jelmer;<contrib>drawing</contrib></author> <pubdate>May 10, 2003</pubdate> </chapterinfo> -<title>File, Directory and Share Access Controls</title> +<title>File, Directory, and Share Access Controls</title> <para> <indexterm><primary>ACLs</primary></indexterm> -Advanced MS Windows users are frequently perplexed when file, directory and share manipulation of +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. @@ -34,7 +34,7 @@ though it does try to bridge the chasm to a degree. <indexterm><primary>Extended Attributes</primary></indexterm> <indexterm><primary>ACLs</primary><secondary>POSIX</secondary></indexterm> -POSIX Access Control List technology has been available (along with Extended Attributes) +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 @@ -66,7 +66,7 @@ beyond early plans and expectations, yet the gap continues to shrink. <itemizedlist> <title>Samba Access Control Facilities</title> <listitem><para> - <indexterm><primary>permissions</primary><secondary>UNIX file and directory</secondary></indexterm> + <indexterm><primary>permissions</primary><secondary>UNIX file and directory</secondary></indexterm> <emphasis>UNIX File and Directory Permissions</emphasis> </para> @@ -89,7 +89,7 @@ beyond early plans and expectations, yet the gap continues to shrink. In configuring share settings and controls in the &smb.conf; 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 + to effect behavior that is more like what MS Windows NT users expect, but it is seldom the <emphasis>best</emphasis> way to achieve this. The basic options and techniques are described herein. </para> @@ -101,8 +101,8 @@ beyond early plans and expectations, yet the gap continues to shrink. </para> <para> - Just like it is possible in MS Windows NT to set ACLs on shares - themselves, so it is possible to do this in Samba. + 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. @@ -120,8 +120,8 @@ beyond early plans and expectations, yet the gap continues to shrink. 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. Sadly, few Linux platforms ship today with native ACLs and - Extended Attributes enabled. This chapter has pertinent information + 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. </para> </listitem> @@ -143,25 +143,24 @@ at how Samba helps to bridge the differences. <title>MS Windows NTFS Comparison with UNIX File Systems</title> <para> -<indexterm><primary>NTFS</primary></indexterm> -<indexterm><primary>File System</primary></indexterm> -<indexterm><primary>File System</primary><secondary>UNIX</secondary></indexterm> -<indexterm><primary>File System</primary><secondary>Windows</secondary></indexterm> - + <indexterm><primary>NTFS</primary></indexterm> + <indexterm><primary>File System</primary></indexterm> + <indexterm><primary>File System</primary><secondary>UNIX</secondary></indexterm> + <indexterm><primary>File System</primary><secondary>Windows</secondary></indexterm> 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 + behavior, that differs from UNIX file system behavior then somehow Samba is responsible for emulating that in a transparent and consistent manner. </para> <para> - 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 over-rides, - but for the greater part we will stay within the bounds of default behavior. Those wishing to explore + 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 &smb.conf; man page. </para> - <para>The following compares file system features for UNIX with those of Microsoft Windows NT/200x: + <para>The following compares file system features for UNIX with those of MS Windows NT/200x: <indexterm><primary>File System</primary><secondary>feature comparison</secondary></indexterm> </para> @@ -171,9 +170,9 @@ at how Samba helps to bridge the differences. <term>Name Space</term> <listitem> <para> - MS Windows NT4/200x/XP files 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 as all names are considered arbitrary. + 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. </para> <para> What MS Windows calls a folder, UNIX calls a directory. @@ -187,7 +186,7 @@ at how Samba helps to bridge the differences. <para> <indexterm><primary>8.3 file names</primary></indexterm> <indexterm><primary>File System</primary><secondary>case sensitivity</secondary></indexterm> - MS Windows file names are generally upper case if made up of 8.3 (8 character file name + 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. </para> @@ -195,10 +194,11 @@ at how Samba helps to bridge the differences. <para> 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 + 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. </para> + <para> Consider the following. All are unique UNIX names but one single MS Windows file name: <screen> @@ -208,74 +208,66 @@ at how Samba helps to bridge the differences. </screen></para> <para> - So clearly, in an MS Windows file name space these three files cannot co-exist, but in UNIX + So clearly, in an MS Windows file namespace these three files cannot co-exist, but in UNIX they can. </para> + <para> 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 &smbmdash; any + accessible to MS Windows users; the others are invisible and unaccessible &smbmdash; any other solution would be suicidal. - </para> - </listitem> + </para></listitem> </varlistentry> <varlistentry> - <term>Directory Separators</term> - <listitem> - - <para> - <indexterm><primary>Directory Separators</primary></indexterm> - MS Windows and DOS uses the backslash <constant>\</constant> as a directory delimiter, and UNIX uses + <term>Directory Separators</term> + <listitem><para> + <indexterm><primary>Directory Separators</primary></indexterm> + MS Windows and DOS use the backslash <constant>\</constant> as a directory delimiter, and UNIX uses the forward-slash <constant>/</constant> as its directory delimiter. This is handled transparently by Samba. - </para> - </listitem> + </para></listitem> </varlistentry> <varlistentry> - <term>Drive Identification</term> - <listitem> - <para> - <indexterm><primary>Drive Identification</primary></indexterm> - MS Windows products support a notion of drive letters, like <command>C:</command> to represent - disk partitions. UNIX has no concept of separate identifiers for file partitions, each + <term>Drive Identification</term> + <listitem><para> + <indexterm><primary>Drive Identification</primary></indexterm> + MS Windows products support a notion of drive letters, like <command>C:</command>, 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 <constant>/</constant> just like the root of a DOS drive is specified as + The UNIX directory tree begins at <constant>/</constant> just as the root of a DOS drive is specified as <constant>C:\</constant>. - </para> - </listitem> + </para></listitem> </varlistentry> <varlistentry> - <term>File Naming Conventions</term> - <listitem> - <para> - <indexterm><primary>File Naming Conventions</primary></indexterm> - MS Windows generally never experiences file names that begin with a dot (<constant>.</constant>) while in UNIX these + <term>File Naming Conventions</term> + <listitem><para> + <indexterm><primary>File Naming Conventions</primary></indexterm> + MS Windows generally never experiences file names that begin with a dot (<constant>.</constant>), while in UNIX these are commonly found in a user's home directory. Files that begin with a dot (<constant>.</constant>) are typically - either start-up files for various UNIX applications, or they may be files that contain - start-up configuration data. - </para> - </listitem> + startup files for various UNIX applications, or they may be files that contain + startup configuration data. + </para></listitem> </varlistentry> <varlistentry> - <term>Links and Short-Cuts</term> - <listitem> - <para> + <term>Links and Short-Cuts</term> + <listitem><para> <indexterm><primary>Links</primary><secondary>hard</secondary></indexterm> <indexterm><primary>Links</primary><secondary>soft</secondary></indexterm> - <indexterm><primary>Short-Cuts</primary></indexterm> - MS Windows make use of <quote>links and short-cuts</quote> that are actually special types of files that will + <indexterm><primary>Shortcuts</primary></indexterm> + MS Windows make use of <emphasis>links and shortcuts</emphasis> 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. </para> + <para> 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 <quote>soft links.</quote> 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. - </para> - </listitem> + </para></listitem> </varlistentry> </variablelist> @@ -291,8 +283,12 @@ at how Samba helps to bridge the differences. <title>Managing Directories</title> <para> - There are three basic operations for managing directories: <command>create, delete, rename</command>. - <table frame="all"> + There are three basic operations for managing directories: <command>create</command>, <command>delete</command>, + <command>rename</command>. <link linkend="TOSH-Accesstbl">Managing Directories with UNIX and + Windows</link> compares the commands in Windows and UNIX that implement these operations. + </para> + + <table frame="all" id="TOSH-Accesstbl"> <title>Managing Directories with UNIX and Windows</title> <tgroup align="center" cols="3"> <thead> @@ -306,20 +302,18 @@ at how Samba helps to bridge the differences. </tbody> </tgroup> </table> - </para> </sect2> <sect2> <title>File and Directory Access Control</title> - <para> <indexterm><primary>ACLs</primary><secondary>File System</secondary></indexterm> The network administrator is strongly advised to read foundational 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 Access Control Lists (ACLs) or Extended - Attributes (EAs). + without having to resort to more complex facilities like POSIX ACLs or extended + attributes (EAs). </para> <para> @@ -345,11 +339,13 @@ drwsrwsrwx 2 maryo gnomes 48 2003-05-12 22:29 muchado08 </para> <para> - The columns above 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. + 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. </para> <para> - An overview of the permissions field can be found in <link linkend="access1">Overview of UNIX permissions field</link>. + An overview of the permissions field is shown in <link linkend="access1">Overview of UNIX permissions + field</link>. </para> <figure id="access1"> @@ -358,26 +354,28 @@ drwsrwsrwx 2 maryo gnomes 48 2003-05-12 22:29 muchado08 </figure> <para> - Any bit flag may be unset. An unset bit flag is the equivalent of <quote>cannot</quote> and is represented - as a <quote>-</quote> character. - - <example> - <title>Example File</title> - <programlisting> - -rwxr-x--- Means: The owner (user) can read, write, execute - the group can read and execute - everyone else cannot do anything with it. - </programlisting> - </example> - + Any bit flag may be unset. An unset bit flag is the equivalent of "cannot" and is represented + as a <quote>-</quote> character (see <link linkend="access2"/>) </para> +<example id="access2"> +<title>Example File</title> +<programlisting> +-rwxr-x--- Means: + ^^^ The owner (user) can read, write, execute + ^^^ the group can read and execute + ^^^ everyone else cannot do anything with it. +</programlisting> +</example> + + <para> - Additional possibilities in the [type] field are: c = character device, b = block device, p = pipe device, s = UNIX Domain Socket. + Additional possibilities in the [type] field are c = character device, b = block device, p = pipe device,r + s = UNIX Domain Socket. </para> <para> - The letters <constant>rwxXst</constant> set permissions for the user, group and others as: read (r), write (w), + The letters <constant>rwxXst</constant> 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 or group ID on execution (s), sticky (t). </para> @@ -396,7 +394,7 @@ drwsrwsrwx 2 maryo gnomes 48 2003-05-12 22:29 muchado08 </para> <para> - When a directory is set <constant>d-wx--x---</constant> this means that the owner can read and create (write) files in it, but because + When a directory is set <constant>d-wx--x---</constant>, 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. @@ -410,20 +408,20 @@ drwsrwsrwx 2 maryo gnomes 48 2003-05-12 22:29 muchado08 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, and has the capability to delete it. + anyone who has the ability to create a file can write to it and has the capability to delete it. </para> <para> 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 had write access, even if that user does not own the file. + user has write access, even if that user does not own the file. </para> <para> 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 <quote>best fit</quote> translation to POSIX ACLs. Some UNIX file systems do however support a feature known - as extended attributes. Only the Windows concept of <quote>inheritance</quote> is implemented by Samba through + 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 <emphasis>inheritance</emphasis> is implemented by Samba through the appropriate extended attribute. </para> @@ -443,32 +441,34 @@ CAP_LINUX_IMMUTABLE capability can set or clear this attribute. server. </para> -<procedure> + <procedure> + <title>Test for file Immutibility Support</title> + <step><para> - Create a file called <filename>filename</filename> + Create a file called <filename>filename</filename>. </para></step> <step><para> Login as the <constant>root</constant> user, then set the immutibile flag on a test file as follows: <screen> -&rootprompt; chatter +i 'filename' +&rootprompt; chatter +i `filename' </screen> </para></step> <step><para> - Login as the user who owns the file (not root) attempt to remove the file as follows: + Login as the user who owns the file (not root) and attempt to remove the file as follows: <screen> mystic:/home/hannibal > rm filename </screen> It will not be possible to delete the file if the immutible flag is correctly honored. </para></step> -</procedure> + </procedure> <para> - On those systems and file system types that support the immutible bit it is possible to create directories - that can not be deleted. Check the man page on your particular host system to determine whether or not + On those 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 - by protected from writing (file creation also) and deletion. + be protected from writing (file creation also) and deletion. </para> </sect3> @@ -481,19 +481,19 @@ mystic:/home/hannibal > rm filename <title>Share Definition Access Controls</title> -<para> -<indexterm><primary>permissions</primary><secondary>share</secondary></indexterm> -The following parameters in the &smb.conf; file sections define a share control or effect access controls. -Before using any of the following options, please refer to the man page for &smb.conf;. -</para> + <para> + <indexterm><primary>permissions</primary><secondary>share</secondary></indexterm> + The following parameters in the &smb.conf; file sections define a share control or affect access controls. + Before using any of the following options, please refer to the man page for &smb.conf;. + </para> <sect2> - <title>User and Group-Based Controls</title> + <title>User- and Group-Based Controls</title> <para> - User and group-based controls can prove quite useful. In some situations it is distinctly desirable to affect all + User- and group-based controls can prove quite useful. In some situations it is distinctly desirable to affect all file system operations as if a single user were doing so. The use of the <smbconfoption name="force user"/> and - <smbconfoption name="force group"/> behavior will achieve this. In other situations it may be necessary to effect a + <smbconfoption name="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 <smbconfoption name="valid users"/> or the <smbconfoption name="invalid users"/> may be most useful. @@ -501,23 +501,23 @@ Before using any of the following options, please refer to the man page for &smb <para> As always, it is highly advisable to use the least difficult 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 finds too great a mess or does not understand what you have done, there is risk of + 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. </para> <para> - <link linkend="ugbc">Following table</link> enumerates these controls. + <link linkend="ugbc">User and Group Based Controls</link> enumerates these controls. </para> - <table frame='all' pgwide='0' id="ugbc"><title>User and Group Based Controls</title> + <table frame='all' pgwide='0' id="ugbc"><title>User- and Group-Based Controls</title> <tgroup cols='2'> <colspec align="left"/> <colspec align="justify" colwidth="1*"/> <thead> <row> <entry align="center">Control Parameter</entry> - <entry align="center">Description - Action - Notes</entry> + <entry align="center">Description, Action, Notes</entry> </row> </thead> <tbody> @@ -525,8 +525,8 @@ Before using any of the following options, please refer to the man page for &smb <entry><smbconfoption name="admin users"/></entry> <entry><para> List of users who will be granted administrative privileges on the share. - They will do all file operations as the super-user (root). - Any user in this list will be able to do anything they like 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. </para></entry> </row> @@ -540,7 +540,7 @@ Before using any of the following options, please refer to the man page for &smb <row> <entry><smbconfoption name="force user"/></entry> <entry><para> - Specifies a UNIX user name that will be assigned as the default user for all users connecting to this service. + 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. </para></entry> </row> @@ -567,13 +567,13 @@ Before using any of the following options, please refer to the man page for &smb <entry><smbconfoption name="read list"/></entry> <entry><para> 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. + will not be given write access, no matter what the read-only option is set to. </para></entry> </row> <row> <entry><smbconfoption name="username"/></entry> <entry><para> - Refer to the &smb.conf; man page for more information -- this is a complex and potentially misused parameter. + Refer to the &smb.conf; man page for more information; this is a complex and potentially misused parameter. </para></entry> </row> <row> @@ -598,25 +598,25 @@ Before using any of the following options, please refer to the man page for &smb <title>File and Directory Permissions-Based Controls</title> <para> - The following file and directory permission-based controls, if misused, can result in considerable difficulty to - diagnose causes of misconfiguration. Use them sparingly and carefully. By gradually introducing each one by one, + The following file and directory permission-based controls, if misused, can result in considerable difficulty in + diagnosing causes of misconfiguration. Use them sparingly and carefully. By gradually introducing them one by one, 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. </para> <para> - Refer to <link linkend="fdpbc">the following table</link> for information regarding the parameters that may be used to affect file and - directory permission-based access controls. + Refer to <link linkend="fdpbc">File and Directory Permission Based Controls</link> for information + regarding the parameters that may be used to affect file and directory permission-based access controls. </para> - <table frame='all' id="fdpbc"><title>File and Directory Permission Based Controls</title> + <table frame='all' id="fdpbc"><title>File and Directory Permission-Based Controls</title> <tgroup cols='2'> <colspec align="left"/> <colspec align="justify" colwidth="1*"/> <thead> <row> <entry align="center">Control Parameter</entry> - <entry align="center">Description - Action - Notes</entry> + <entry align="center">Description, Action, Notes</entry> </row> </thead> <tbody> @@ -630,7 +630,7 @@ Before using any of the following options, please refer to the man page for &smb <entry><smbconfoption name="directory mask"/></entry> <entry><para> The octal modes used when converting DOS modes to UNIX modes when creating UNIX directories. - See also: directory security mask. + See also directory security mask. </para></entry></row> <row> <entry><smbconfoption name="dos filemode"/></entry> @@ -641,13 +641,13 @@ Before using any of the following options, please refer to the man page for &smb <row> <entry><smbconfoption name="force create mode"/></entry> <entry><para> - This parameter specifies a set of UNIX mode bit permissions that will always be set on a file created by Samba. + This parameter specifies a set of UNIX-mode bit permissions that will always be set on a file created by Samba. </para></entry> </row> <row> <entry><smbconfoption name="force directory mode"/></entry> <entry><para> - This parameter specifies a set of UNIX mode bit permissions that will always be set on a directory created by Samba. + This parameter specifies a set of UNIX-mode bit permissions that will always be set on a directory created by Samba. </para></entry> </row> <row> @@ -671,13 +671,13 @@ Before using any of the following options, please refer to the man page for &smb <row> <entry><smbconfoption name="hide unwriteable files"/></entry> <entry><para> - Prevents clients from seeing the existence of files that cannot be written to. Unwriteable directories are shown as usual. + Prevents clients from seeing the existence of files that cannot be written to. Unwritable directories are shown as usual. </para></entry> </row> <row> <entry><smbconfoption name="nt acl support"/></entry> <entry><para> - This parameter controls whether smbd will attempt to map UNIX permissions into Windows NT access control lists. + This parameter controls whether smbd will attempt to map UNIX permissions into Windows NT ACLs. </para></entry> </row> <row> @@ -697,7 +697,8 @@ Before using any of the following options, please refer to the man page for &smb <para> The following are documented because of the prevalence of administrators creating inadvertent barriers to file - access by not understanding the full implications of &smb.conf; file settings. See <link linkend="mcoc">following table</link>. + access by not understanding the full implications of &smb.conf; file settings. + See <link linkend="mcoc">Other Controls</link>. </para> <table frame='all' id="mcoc"><title>Other Controls</title> @@ -707,7 +708,7 @@ Before using any of the following options, please refer to the man page for &smb <thead> <row> <entry align="center">Control Parameter</entry> - <entry align="center">Description - Action - Notes</entry> + <entry align="center">Description, Action, Notes</entry> </row> </thead> <tbody> @@ -718,14 +719,14 @@ Before using any of the following options, please refer to the man page for &smb <smbconfoption name="short preserve case"/> </entry> <entry><para> - This means that all file name lookup will be done in a case sensitive manner. + 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. </para></entry> </row> <row> <entry><smbconfoption name="csc policy"/></entry> <entry><para> - Client Side Caching Policy - parallels MS Windows client side file caching capabilities. + Client-side caching policy parallels MS Windows client-side file caching capabilities. </para></entry> </row> <row> @@ -743,7 +744,7 @@ Before using any of the following options, please refer to the man page for &smb <row> <entry><smbconfoption name="dos filetimes"/></entry> <entry><para> - DOS and Windows allow users to change file time stamps if they can write to the file. POSIX semantics prevent this. + 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. </para></entry> </row> @@ -751,7 +752,7 @@ Before using any of the following options, please refer to the man page for &smb <entry><smbconfoption name="fake oplocks"/></entry> <entry><para> 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. + oplock, the client is free to assume that it is the only one accessing the file, and it will aggressively cache file data. </para></entry> </row> <row> @@ -761,7 +762,7 @@ Before using any of the following options, please refer to the man page for &smb <smbconfoption name="veto files"/> </entry> <entry><para> - Note: MS Windows Explorer allows over-ride of files marked as hidden so they will still be visible. + Note: MS Windows Explorer allows override of files marked as hidden so they will still be visible. </para></entry> </row> <row> @@ -789,53 +790,57 @@ Before using any of the following options, please refer to the man page for &smb <para> -<indexterm><primary>permissions</primary><secondary>share ACLs</secondary></indexterm> - This section deals with how to configure Samba per share access control restrictions. + <indexterm><primary>permissions</primary><secondary>share ACLs</secondary></indexterm> + 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 + connect to a share. In the absence of specific restrictions, the default setting is to allow the global user <constant>Everyone - Full Control</constant> (full control, change and read). </para> <para> - At this time Samba does not provide a tool for configuring access control setting on the share + At this time Samba does not provide a tool for configuring access control settings on the share itself. Samba does have the capacity to store and act on access control settings, but the only - way to create those settings is to use either the NT4 Server Manager or the Windows 200x MMC for - Computer Management. + way to create those settings is to use either the NT4 Server Manager or the Windows 200x + Microsoft Management Console (MMC) for Computer Management. </para> <para> - Samba stores the per share access control settings in a file called <filename>share_info.tdb</filename>. + Samba stores the per-share access control settings in a file called <filename>share_info.tdb</filename>. 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 <filename>/usr/local/samba/var</filename>. If the <filename>tdbdump</filename> utility has been compiled and installed on your system, then you can examine the contents of this file - by executing: <command>tdbdump share_info.tdb</command> in the directory containing the tdb files. + by executing <command>tdbdump share_info.tdb</command> in the directory containing the tdb files. </para> <sect2> <title>Share Permissions Management</title> <para> - The best tool for the task is platform dependant. Choose the best tool for your environment. + The best tool for share permissions management is platform-dependent. Choose the best tool for your environment. </para> <sect3> <title>Windows NT4 Workstation/Server</title> <para> - The tool you need to use to manage share permissions on a Samba 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 Microsoft &smbmdash; see details below. + The tool you can use 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 <ulink +url="http://support.microsoft.com/default.aspx?scid=kb;en-us;173673">support</ulink> section. </para> <procedure> <title>Instructions</title> + <step><para> - Launch the <application>NT4 Server Manager</application>, click on the Samba server you want to administer. From the menu - select <guimenu>Computer</guimenu>, then click on <guimenuitem>Shared Directories</guimenuitem>. + Launch the <application>NT4 Server Manager</application> and click on the Samba server you want to + administer. From the menu select <guimenu>Computer</guimenu>, then click on + <guimenuitem>Shared Directories</guimenuitem>. </para></step> <step><para> - Click on the share that you wish to manage, then click the <guilabel>Properties</guilabel> tab. then click + Click on the share that you wish to manage and click the <guilabel>Properties</guilabel> tab. then click the <guilabel>Permissions</guilabel> tab. Now you can add or change access control settings as you wish. </para></step> </procedure> @@ -846,22 +851,22 @@ Before using any of the following options, please refer to the man page for &smb <title>Windows 200x/XP</title> <para> - On <application>MS Windows NT4/200x/XP</application> system access control lists on the share itself are set using native - tools, usually from File Manager. For example, in Windows 200x, right click on the shared folder, + On <application>MS Windows NT4/200x/XP</application> 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 <guimenuitem>Sharing</guimenuitem>, then click on <guilabel>Permissions</guilabel>. The default - Windows NT4/200x permission allows <quote>Everyone</quote> full control on the share. + Windows NT4/200x permission allows "Everyone" full control on the share. </para> <para> - MS Windows 200x and later versions come with a tool called the <application>Computer Management</application> snap-in for the - Microsoft Management Console (MMC). This tool is located by clicking on <guimenu>Control Panel -> + MS Windows 200x and later versions come with a tool called the <application>Computer Management</application> + snap-in for the MMC. This tool is located by clicking on <guimenu>Control Panel -> Administrative Tools -> Computer Management</guimenu>. </para> <procedure> <title>Instructions</title> <step><para> - After launching the MMC with the Computer Management snap-in, click the menu item <guimenuitem>Action</guimenuitem>, + After launching the MMC with the Computer Management snap-in, click the menu item <guimenuitem>Action</guimenuitem> and select <guilabel>Connect to another computer</guilabel>. 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. @@ -870,8 +875,8 @@ Before using any of the following options, please refer to the man page for &smb <step><para> If the Samba server is not shown in the <guilabel>Select Computer</guilabel> box, type in the name of the target Samba server in the field <guilabel>Name:</guilabel>. Now click the on <guibutton>[+]</guibutton> next to - <guilabel>System Tools</guilabel>, then on the <guibutton>[+]</guibutton> next to <guilabel>Shared Folders</guilabel> in the - left panel. + <guilabel>System Tools</guilabel>, then on the <guibutton>[+]</guibutton> next to + <guilabel>Shared Folders</guilabel> in the left panel. </para></step> <step><para> @@ -884,10 +889,11 @@ Before using any of the following options, please refer to the man page for &smb <warning> <para> - Be careful. If you take away all permissions from the <constant>Everyone</constant> 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 <emphasis>no access</emphasis> means that <constant>MaryK</constant> who is part of the group - <constant>Everyone</constant> will have no access even if she is given explicit full control access. + Be careful. If you take away all permissions from the <constant>Everyone</constant> 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 <emphasis>no access</emphasis> means that <constant>MaryK</constant> who is + part of the group <constant>Everyone</constant> will have no access even if she is given explicit full + control access. </para> </warning> @@ -904,13 +910,13 @@ Before using any of the following options, please refer to the man page for &smb <para> -<indexterm><primary>permissions</primary><secondary>file/directory ACLs</secondary></indexterm> + <indexterm><primary>permissions</primary><secondary>file/directory ACLs</secondary></indexterm> Windows NT clients can use their native security settings dialog box to view and modify the underlying UNIX permissions. </para> <para> - This ability is careful not to compromise the security of the UNIX host on which Samba is running, and + 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. </para> @@ -933,15 +939,15 @@ Before using any of the following options, please refer to the man page for &smb <title>Viewing File Security on a Samba Share</title> <para> - From an NT4/2000/XP client, right click on any file or directory in a Samba-mounted drive letter + 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 <guilabel>Properties</guilabel> entry at the bottom of the menu. This brings up the file <constant>Properties</constant> dialog box. Click on the <guilabel>Security</guilabel> tab and you will see three buttons: <guibutton>Permissions</guibutton>, <guibutton>Auditing</guibutton>, and <guibutton>Ownership</guibutton>. The <guibutton>Auditing</guibutton> - button will cause either an error message <errorname>`A requested privilege is not held by the client'</errorname> - 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 <guibutton>Add</guibutton> + button will cause either an error message <errorname>"A requested privilege is not held by the client"</errorname> + 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 <guibutton>Add</guibutton> button, will not currently allow a list of users to be seen. </para> @@ -961,7 +967,7 @@ Before using any of the following options, please refer to the man page for &smb <para> <replaceable>SERVER</replaceable> is the NetBIOS name of the Samba server, <replaceable>user</replaceable> - is the user name of the UNIX user who owns the file, and <replaceable>(Long name)</replaceable> is the + is the username of the UNIX user who owns the file, and <replaceable>(Long name)</replaceable> is the descriptive string identifying the user (normally found in the GECOS field of the UNIX password database). Click on the <guibutton>Close </guibutton> button to remove this dialog. </para> @@ -973,17 +979,19 @@ Before using any of the following options, please refer to the man page for &smb <para> The <guibutton>Take Ownership</guibutton> 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 you are currently logged onto + 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 <emphasis>root</emphasis> user. As clicking on this button causes + operation in UNIX, available only to the <emphasis>root</emphasis> 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.</para> + not work with Samba at this time. + </para> <para> - There is an NT <command>chown</command> 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 filesystem or remote mounted NTFS - or Samba drive. This is available as part of the <application>Seclib</application> NT security library written - by Jeremy Allison of the Samba Team, and is available from the main Samba FTP site.</para> + There is an NT <command>chown</command> 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 <application>Seclib</application> NT + security library written by Jeremy Allison of the Samba Team and is downloadable from the main Samba FTP site. + </para> </sect2> @@ -991,7 +999,7 @@ Before using any of the following options, please refer to the man page for &smb <title>Viewing File or Directory Permissions</title> <para> - The third button is the <guibutton>Permissions</guibutton> button. Clicking on this brings up a dialog box + The third button is the <guibutton>Permissions</guibutton> 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: </para> @@ -999,238 +1007,271 @@ Before using any of the following options, please refer to the man page for &smb <replaceable>user</replaceable> <replaceable>(Long name)</replaceable></command></para> - <para>Where <replaceable>SERVER</replaceable> is the NetBIOS name of the Samba server, - <replaceable>user</replaceable> is the user name of the UNIX user who owns the file, and + <para><replaceable>SERVER</replaceable> is the NetBIOS name of the Samba server, + <replaceable>user</replaceable> is the username of the UNIX user who owns the file, and <replaceable>(Long name)</replaceable> is the descriptive string identifying the user (normally found in the GECOS field of the UNIX password database).</para> <para> If the parameter <smbconfoption name="nt acl support"/> is set to <constant>false</constant>, - the file owner will be shown as the NT user <constant>Everyone</constant> and the permissions will be - shown as NT <quote>Full Control</quote>. + the file owner will be shown as the NT user <constant>Everyone</constant>, and the permissions will be + shown as NT <emphasis>Full Control</emphasis>. </para> <para> - The permissions field is displayed differently for files and directories, both are discussed here: + The permissions field is displayed differently for files and directories, both are discussed next. </para> <sect3> - <title>File Permissions</title> - - <para>The standard UNIX user/group/world triplet and the corresponding <constant>read, write, execute</constant> permissions - triplets are mapped by Samba into a three element NT ACL with the <quote>r</quote>, <quote>w</quote> and <quote>x</quote> bits mapped into the corresponding - NT permissions. The UNIX world permissions are mapped into the global NT group <constant>Everyone</constant>, followed - by the list of permissions allowed for the UNIX world. The UNIX owner and group permissions are displayed as an NT - <guiicon>user</guiicon> icon and an NT <guiicon>local group</guiicon> icon, respectively, followed by the list - of permissions allowed for the UNIX user and group.</para> - - <para>Because many UNIX permission sets do not map into common NT names such as <constant>read</constant>, - <constant>change</constant> or <constant>full control</constant>, usually the permissions will be prefixed - by the words <constant>Special Access</constant> in the NT display list.</para> - - <para>But what happens if the file has no permissions allowed for a particular UNIX user group or world component? In order - to allow <quote>no permissions</quote> to be seen and modified Samba then overloads the NT <constant>Take Ownership</constant> ACL attribute - (which has no meaning in UNIX) and reports a component with no permissions as having the NT <command>O</command> bit set. - This was chosen, of course, to make it look like a zero, meaning zero permissions. More details on the decision behind this is - given below.</para> + <title>File Permissions</title> + + <para> + The standard UNIX user/group/world triplet and the corresponding <constant>read, write, + execute</constant> permissions triplets are mapped by Samba into a three-element NT ACL with the + <quote>r</quote>, <quote>w</quote>, and <quote>x</quote> bits mapped into the corresponding NT + permissions. The UNIX world permissions are mapped into the global NT group <constant>Everyone</constant>, followed + by the list of permissions allowed for the UNIX world. The UNIX owner and group permissions are displayed as an NT + <guiicon>user</guiicon> icon and an NT <guiicon>local group</guiicon> icon, respectively, followed by the list + of permissions allowed for the UNIX user and group. + </para> + + <para> + Because many UNIX permission sets do not map into common NT names such as <constant>read</constant>, + <constant>change</constant>, or <constant>full control</constant>, usually the permissions will be prefixed + by the words <constant>Special Access</constant> in the NT display list. + </para> + + <para> + But what happens if the file has no permissions allowed for a particular UNIX user group or world component? + In order to allow <emphasis>no permissions</emphasis> to be seen and modified, Samba then overloads the NT + <constant>Take Ownership</constant> ACL attribute (which has no meaning in UNIX) and reports a component with + no permissions as having the NT <command>O</command> 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. + </para> + </sect3> <sect3> - <title>Directory Permissions</title> + <title>Directory Permissions</title> - <para>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 <constant>RW</constant> - 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.</para> + <para> + 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 <constant>RW</constant> + 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. + </para> - <para>The second set of directory permissions has no real meaning in the UNIX permissions world and represents the <constant> - inherited</constant> permissions that any file created within this directory would inherit.</para> + <para> + The second set of directory permissions has no real meaning in the UNIX permissions world and represents the <constant> + inherited</constant> permissions that any file created within this directory would inherit. + </para> + + <para> + 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. + </para> - <para>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.</para> </sect3> + </sect2> <sect2> - <title>Modifying File or Directory Permissions</title> - - <para>Modifying file and directory permissions is as simple - as changing the displayed permissions in the dialog box, and - clicking on <guibutton>OK</guibutton>. 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.</para> - - <para>If the parameter <smbconfoption name="nt acl support"/> - is set to <constant>false</constant>, any attempt to set - security permissions will fail with an <errorname>`Access Denied' - </errorname> message.</para> - - <para>The first thing to note is that the <guibutton>Add</guibutton> - button will not return a list of users in Samba (it will give - an error message saying <errorname>`The remote procedure call failed - and did not execute'</errorname>). 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.</para> - - <para>If a permission triplet (either user, group, or world) - is removed from the list of permissions in the NT dialog box, - then when the <guibutton>OK</guibutton> button is pressed it will - be applied as <quote>no permissions</quote> on the UNIX side. If you then - view the permissions again, the <quote>no permissions</quote> entry will appear - as the NT <command>O</command> 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.</para> - - <para>As UNIX supports only the <quote>r</quote>, <quote>w</quote> and <quote>x</quote> bits of - an NT ACL, if other NT security attributes such as <constant>Delete Access</constant> are - selected they will be ignored when applied on the Samba server.</para> - - <para>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 un-check the <guilabel>Replace - permissions on existing files</guilabel> check-box in the NT - dialog before clicking on <guibutton>OK</guibutton>.</para> - - <para>If you wish to remove all permissions from a - user/group/world component, you may either highlight the - component and click on the <guibutton>Remove</guibutton> button, - or set the component to only have the special <constant>Take - Ownership</constant> permission (displayed as <command>O - </command>) highlighted.</para> - </sect2> + <title>Modifying File or Directory Permissions</title> - <sect2> - <title>Interaction with the Standard Samba <quote>create mask</quote> Parameters</title> + <para> + Modifying file and directory permissions is as simple as changing the displayed permissions in the dialog box + and clicking on <guibutton>OK</guibutton>. 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. + </para> - <para>There are four parameters that control interaction with the standard Samba <parameter>create mask</parameter> parameters. - These are: + <para> + If the parameter <smbconfoption name="nt acl support"/> is set to <constant>false</constant>, any attempt to + set security permissions will fail with an <errorname>"Access Denied" </errorname> message. + </para> - <itemizedlist> - <listitem><para><smbconfoption name="security mask"/></para></listitem> - <listitem><para><smbconfoption name="force security mode"/></para></listitem> - <listitem><para><smbconfoption name="directory security mask"/></para></listitem> - <listitem><para><smbconfoption name="force directory security mode"/></para></listitem> - </itemizedlist> + <para> + The first thing to note is that the <guibutton>Add</guibutton> button will not return a list of users in Samba + (it will give an error message saying <errorname>"The remote procedure call failed and did not + execute"</errorname>). 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. + </para> - </para> + <para> + If a permission triplet (either user, group, or world) is removed from the list of permissions in the NT + dialog box, then when the <guibutton>OK</guibutton> button is pressed, it will be applied as <emphasis>no + permissions</emphasis> on the UNIX side. If you view the permissions again, the <emphasis>no + permissions</emphasis> entry will appear as the NT <command>O</command> 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. + </para> - <para>When a user clicks on <guibutton>OK</guibutton> 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 - <smbconfoption name="security mask"/> parameter. Any bits that - were changed that are not set to <quote>1</quote> in this parameter are left alone - in the file permissions.</para> - - <para>Essentially, zero bits in the <smbconfoption name="security mask"/> - may be treated as a set of bits the user is <emphasis>not</emphasis> - allowed to change, and one bits are those the user is allowed to change. - </para> + <para> + Because UNIX supports only the <quote>r</quote>, <quote>w</quote>, and <quote>x</quote> bits of an NT ACL, if + other NT security attributes such as <constant>Delete Access</constant> are selected, they will be ignored + when applied on the Samba server. + </para> - <para>If not explicitly set, this parameter defaults to the same value as - the <smbconfoption name="create mask"/> parameter. To allow a user to modify all the - user/group/world permissions on a file, set this parameter to 0777. - </para> + <para> + 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 + <guilabel>Replace permissions on existing files</guilabel> checkbox in the NT dialog before clicking on + <guibutton>OK</guibutton>. + </para> - <para>Next Samba checks the changed permissions for a file against the bits set in the - <smbconfoption name="force security mode"/> parameter. Any bits - that were changed that correspond to bits set to <quote>1</quote> in this parameter - are forced to be set.</para> - - <para>Essentially, bits set in the <parameter>force security mode</parameter> parameter - may be treated as a set of bits that, when modifying security on a file, the user has always set to be <quote>on</quote>.</para> - - <para>If not explicitly set, this parameter defaults to the same value - as the <smbconfoption name="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 - <smbconfoption name="security mask"/> and <parameter>force - security mode</parameter> parameters are applied to the change - request in that order.</para> - - <para>For a directory, Samba will perform the same operations as - described above for a file except it uses the parameter <parameter> - directory security mask</parameter> instead of <parameter>security - mask</parameter>, and <parameter>force directory security mode - </parameter> parameter instead of <parameter>force security mode - </parameter>.</para> - - <para>The <smbconfoption name="directory security mask"/> parameter - by default is set to the same value as the <parameter>directory mask - </parameter> parameter and the <parameter>force directory security - mode</parameter> parameter by default is set to the same value as - the <smbconfoption name="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.</para> - - <para>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 <quote>on</quote>, then set the following - parameters in the &smb.conf; file in that share-specific section: - </para> + <para> + If you wish to remove all permissions from a user/group/world component, you may either highlight the + component and click on the <guibutton>Remove</guibutton> button or set the component to only have the special + <constant>Take Ownership</constant> permission (displayed as <command>O</command>) highlighted. + </para> - <smbconfblock> - <smbconfoption name="security mask">0777</smbconfoption> - <smbconfoption name="force security mode">0</smbconfoption> - <smbconfoption name="directory security mask">0777</smbconfoption> - <smbconfoption name="force directory security mode">0</smbconfoption> - </smbconfblock> </sect2> <sect2> - <title>Interaction with the Standard Samba File Attribute Mapping</title> + <title>Interaction with the Standard Samba <quote>create mask</quote> Parameters</title> - <note> - <para>Samba maps some of the DOS attribute bits (such as <quote>read - only</quote>) 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. - </para> - </note> + <para>There are four parameters that control interaction with the standard Samba <parameter>create mask</parameter> parameters: + + + <itemizedlist> + <listitem><para><smbconfoption name="security mask"/></para></listitem> + <listitem><para><smbconfoption name="force security mode"/></para></listitem> + <listitem><para><smbconfoption name="directory security mask"/></para></listitem> + <listitem><para><smbconfoption name="force directory security mode"/></para></listitem> + </itemizedlist> + + </para> + + <para> + When a user clicks on <guibutton>OK</guibutton> 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 + <smbconfoption name="security mask"/> parameter. Any bits that + were changed that are not set to <emphasis>1</emphasis> in this parameter are left alone + in the file permissions.</para> + + <para> + Essentially, zero bits in the <smbconfoption name="security mask"/> + may be treated as a set of bits the user is <emphasis>not</emphasis> + allowed to change, and one bits are those the user is allowed to change. + </para> + + <para> + If not explicitly set, this parameter defaults to the same value as + the <smbconfoption name="create mask"/> parameter. To allow a user to modify all the + user/group/world permissions on a file, set this parameter to 0777. + </para> + + <para> + Next Samba checks the changed permissions for a file against the bits set in the + <smbconfoption name="force security mode"/> parameter. Any bits + that were changed that correspond to bits set to <emphasis>1</emphasis> in this parameter + are forced to be set.</para> + + <para> + Essentially, bits set in the <parameter>force security mode</parameter> parameter + may be treated as a set of bits that, when modifying security on a file, the user + has always set to be <emphasis>on</emphasis>.</para> + + <para> + If not explicitly set, this parameter defaults to the same value + as the <smbconfoption name="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 + <smbconfoption name="security mask"/> and <parameter>force + security mode</parameter> parameters are applied to the change + request in that order.</para> + + <para> + For a directory, Samba performs the same operations as + described above for a file except it uses the parameter <parameter> + directory security mask</parameter> instead of <parameter>security + mask</parameter>, and <parameter>force directory security mode + </parameter> parameter instead of <parameter>force security mode + </parameter>.</para> + + <para> + The <smbconfoption name="directory security mask"/> parameter + by default is set to the same value as the <parameter>directory mask + </parameter> parameter and the <parameter>force directory security + mode</parameter> parameter by default is set to the same value as + the <smbconfoption name="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.</para> + + <para> + 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 <emphasis>on</emphasis>, + then set the following parameters in the &smb.conf; file in that + share-specific section: + <smbconfblock> + <smbconfoption name="security mask">0777</smbconfoption> + <smbconfoption name="force security mode">0</smbconfoption> + <smbconfoption name="directory security mask">0777</smbconfoption> + <smbconfoption name="force directory security mode">0</smbconfoption> + </smbconfblock> + </para> +</sect2> + +<sect2> + <title>Interaction with the Standard Samba File Attribute Mapping</title> + + <note> + <para> + Samba maps some of the DOS attribute bits (such as <quote>read-only</quote>) + 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. + </para> + </note> + + <para> + If a file has no UNIX read access for the owner, it will show up + as <quote>read-only</quote> in the standard file attributes tabbed dialog. + Unfortunately, this dialog is the same one that contains the security information + in another tab. + </para> + + <para> + 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 + <guibutton>OK</guibutton> to get back to the standard attributes tab + dialog, and clicks on <guibutton>OK</guibutton> 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 <guibutton>OK</guibutton> to get back to the + attributes dialog, you should always press <guibutton>Cancel</guibutton> + rather than <guibutton>OK</guibutton> to ensure that your changes + are not overridden. + </para> - <para>If a file has no UNIX read access for the owner, it will show up - as <quote>read only</quote> in the standard file attributes tabbed dialog. - Unfortunately, this dialog is the same one that contains the security information - in another tab.</para> - - <para>What this can mean is that if the owner changes the permissions - to allow himself read access using the security dialog, clicks on - <guibutton>OK</guibutton> to get back to the standard attributes tab - dialog, and clicks on <guibutton>OK</guibutton> 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 <guibutton>OK</guibutton> to get back to the - attributes dialog, you should always press <guibutton>Cancel</guibutton> - rather than <guibutton>OK</guibutton> to ensure that your changes - are not overridden.</para> </sect2> <sect2> - <title>Windows NT/200X ACLS and POSIX ACLS &smbmdash; Limitations</title> + <title>Windows NT/200X ACLs and POSIX ACLs Limitations</title> <para> - Windows administrators are familiar with simple ACL controls and they typically + 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. </para> <para> Competing SMB implementations differ in how they handle Windows ACLs. Samba handles - Windows ACLs from the perspective of UNIX file system adminsitration and thus adopts + 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. </para> <para> - POSIX ACLs present an interesting challenge to the UNIX adminsitrator and therfore a + 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 + 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. </para> @@ -1239,7 +1280,7 @@ Before using any of the following options, please refer to the man page for &smb 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 noticibly increased the pressure to + The pressure for ACLs support in Samba has noticeably increased the pressure to standardize ACLs support in the UNIX world. </para> @@ -1258,15 +1299,15 @@ Before using any of the following options, please refer to the man page for &smb In examining POSIX ACLs we must consider the manner in which they operate for both files and directories. File ACLs have the following significance: <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) +# 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) </screen> Directory ACLs have the following signficance: <screen> @@ -1275,10 +1316,10 @@ other::--- <-- perms applied to everyone else (other) # 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 +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: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) @@ -1292,8 +1333,9 @@ default:other:--- <-- inherited permissions for everyone (other) <para> Microsoft Windows NT4/200X ACLs must of necessity be mapped to POSIX ACLs. - The mappings for file permissions are shown in <link linkend="fdsacls"/>. - The '#' character means this flag is set only when the Windows administrator + The mappings for file permissions are shown in <link linkend="fdsacls">How + Windows File ACLs Map to UNIX POSIX File ACLs</link>. + The # character means this flag is set only when the Windows administrator sets the <constant>Full Control</constant> flag on the file. </para> @@ -1313,11 +1355,11 @@ default:other:--- <-- inherited permissions for everyone (other) <entry><para>#</para></entry> </row> <row> - <entry><para>Traverse Folder / Execute File</para></entry> + <entry><para>Traverse Folder/Execute File</para></entry> <entry><para>x</para></entry> </row> <row> - <entry><para>List Folder / Read Data</para></entry> + <entry><para>List Folder/Read Data</para></entry> <entry><para>r</para></entry> </row> <row> @@ -1329,11 +1371,11 @@ default:other:--- <-- inherited permissions for everyone (other) <entry><para>r</para></entry> </row> <row> - <entry><para>Create Files / Write Data</para></entry> + <entry><para>Create Files/Write Data</para></entry> <entry><para>w</para></entry> </row> <row> - <entry><para>Create Folders / Append Data</para></entry> + <entry><para>Create Folders/Append Data</para></entry> <entry><para>w</para></entry> </row> <row> @@ -1369,21 +1411,21 @@ default:other:--- <-- inherited permissions for everyone (other) </table> <para> - As can be seen from the mapping table, there is no 1:1 mapping capability and therefore + 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. + that is intended by the administrator. </para> <para> In general the mapping of UNIX POSIX user/group/other permissions will be mapped to - Windows ALCs. This has precidence over the creation of POSIX ACLs. POSIX ACLs are necessary + 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. </para> <para> 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 the + The Windows administrator is more restricted in that it is not possible from within Windows Explorer to remove read permission for the file owner. </para> @@ -1394,8 +1436,8 @@ default:other:--- <-- inherited permissions for everyone (other) <para> Interesting things happen in the mapping of UNIX POSIX directory permissions as well - as UNIX POSIX ACLs to Windows ACEs (Access Control Entries, the discrete component of - an Access Control List (ACL), are mapped to Windows directory ACLs. + as UNIX POSIX ACLs to Windows ACEs (Access Control Entries, the discrete components of + an ACLs when they are mapped to Windows directory ACLs. </para> <para> @@ -1413,8 +1455,8 @@ default:other:--- <-- inherited permissions for everyone (other) <title>Common Errors</title> <para> -File, directory and share access problems are common on the mailing list. The following -are examples taken from the mailing list in recent times. +File, directory, and share access problems are common topics on the mailing list. The following +are examples recently taken from the mailing list. </para> @@ -1423,15 +1465,16 @@ are examples taken from the mailing list in recent times. <para> <quote> - We are facing some troubles with file/directory permissions. I can log on the domain as admin user(root), + 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 - <userinput>chgrp -R users *</userinput> and <userinput>chown -R nobody *</userinput> to allow others users to change the file. + <userinput>chgrp -R users *</userinput> and <userinput>chown -R nobody *</userinput> to allow + others users to change the file. </quote> </para> <para> - There are many ways to solve this problem and here are a few hints: + There are many ways to solve this problem, and here are a few hints: </para> <procedure> @@ -1443,12 +1486,12 @@ are examples taken from the mailing list in recent times. <step> <para> - Set the ownership to what ever public owner and group you want + Set the ownership to whatever public owner and group you want <screen> -&prompt;find 'directory_name' -type d -exec chown user.group {}\; -&prompt;find 'directory_name' -type d -exec chmod 1775 'directory_name' -&prompt;find 'directory_name' -type f -exec chmod 0775 {} \; -&prompt;find 'directory_name' -type f -exec chown user.group {}\; +&prompt;find `directory_name' -type d -exec chown user.group {}\; +&prompt;find `directory_name' -type d -exec chmod 1775 `directory_name' +&prompt;find `directory_name' -type f -exec chmod 0775 {} \; +&prompt;find `directory_name' -type f -exec chown user.group {}\; </screen> </para> @@ -1462,7 +1505,7 @@ are examples taken from the mailing list in recent times. <step> <para> - Directory is: <replaceable>/foodbar</replaceable> + Directory is <replaceable>/foodbar</replaceable>: <screen> &prompt;<userinput>chown jack.engr /foodbar</userinput> </screen> @@ -1523,7 +1566,7 @@ drwsrwsr-x 2 jack engr 48 2003-02-04 09:55 foodbar <note><para> These procedures are needed only if your users are not members of the group - you have used. That is if within the OS do not have write permission on the directory. + you have used &smbmdash; that is, if within the OS they do not have write permission on the directory. </para> </note> @@ -1552,22 +1595,22 @@ drwsrwsr-x 2 jack engr 48 2003-02-04 09:55 foodbar <title>MS Word with Samba Changes Owner of File</title> <para> - <emphasis>Question:</emphasis> <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?</quote> + <emphasis>Question:</emphasis> <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?</quote> </para> <para> - <emphasis>Answer:</emphasis> 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, Word then renames the new document to the original document name. + <emphasis>Answer:</emphasis> 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. + to tell, the file that gets created is a new file, not one that the application (Word) is updating. </para> <para> - There is a work-around to solve the permissions problem. That work-around involves understanding how you can manage file + There is a workaround to solve the permissions problem. It involves understanding how you can manage file system behavior from within the &smb.conf; file, as well as understanding how UNIX file systems work. Set on the directory - in which you are changing Word documents: <command>chmod g+s `directory_name'</command> This ensures that all files will + in which you are changing Word documents: <command>chmod g+s `directory_name'.</command> This ensures that all files will be created with the group that owns the directory. In &smb.conf; share declaration section set: </para> @@ -1579,7 +1622,7 @@ drwsrwsr-x 2 jack engr 48 2003-02-04 09:55 foodbar </para> <para> - These two settings will ensure that all directories and files that get created in the share will be read/writable by the + 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. </para> |