testsuite/systemtap.string/isinstr.stp


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probe begin
{
	a = "foo"
	str = "abcfoobad"

	if (isinstr(str,a))
		printf("\"%s\" is in \"%s\"\n", a, str)
	else
		printf("\"%s\" is NOT in \"%s\"\n", a, str)

	str = "abcdefg"
	if (isinstr(str,a))
		printf("\"%s\" is in \"%s\"\n", a, str)
	else
		printf("\"%s\" is NOT in \"%s\"\n", a, str)

	a = ""
	str = ""
	if (isinstr(str,a))
		printf("\"%s\" is in \"%s\"\n", a, str)
	else
		printf("\"%s\" is NOT in \"%s\"\n", a, str)

        exit()
}
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><HEAD
><TITLE
>UNIX Permission Bits and Windows NT Access Control Lists</TITLE
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><HR
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><DIV
CLASS="CHAPTER"
><H1
><A
NAME="UNIX-PERMISSIONS"
></A
>Chapter 11. UNIX Permission Bits and Windows NT Access Control Lists</H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
>11.1. <A
HREF="unix-permissions.html#AEN1533"
>Viewing and changing UNIX permissions using the NT 
	security dialogs</A
></DT
><DT
>11.2. <A
HREF="unix-permissions.html#AEN1539"
>How to view file security on a Samba share</A
></DT
><DT
>11.3. <A
HREF="unix-permissions.html#AEN1550"
>Viewing file ownership</A
></DT
><DT
>11.4. <A
HREF="unix-permissions.html#AEN1570"
>Viewing file or directory permissions</A
></DT
><DD
><DL
><DT
>11.4.1. <A
HREF="unix-permissions.html#AEN1585"
>File Permissions</A
></DT
><DT
>11.4.2. <A
HREF="unix-permissions.html#AEN1599"
>Directory Permissions</A
></DT
></DL
></DD
><DT
>11.5. <A
HREF="unix-permissions.html#AEN1606"
>Modifying file or directory permissions</A
></DT
><DT
>11.6. <A
HREF="unix-permissions.html#AEN1628"
>Interaction with the standard Samba create mask 
	parameters</A
></DT
><DT
>11.7. <A
HREF="unix-permissions.html#AEN1681"
>Interaction with the standard Samba file attribute 
	mapping</A
></DT
></DL
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1533"
>11.1. Viewing and changing UNIX permissions using the NT 
	security dialogs</A
></H1
><P
>Windows NT clients can use their native security settings 
	dialog box to view and modify the underlying UNIX permissions.</P
><P
>Note that this ability is careful not to compromise 
	the security of the UNIX host Samba is running on, and 
	still obeys all the file permission rules that a Samba 
	administrator can set.</P
><DIV
CLASS="NOTE"
><P
></P
><TABLE
CLASS="NOTE"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="/usr/share/sgml/docbook/stylesheet/dsssl/modular/images/note.gif"
HSPACE="5"
ALT="Note"></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>	All access to Unix/Linux system file via Samba is controlled at
	the operating system file access control level. When trying to
	figure out file access problems it is vitally important to identify
	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
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1539"
>11.2. How to view file security on a Samba share</A
></H1
><P
>From an NT4/2000/XP client, single-click with the right 
	mouse button on any file or directory in a Samba mounted 
	drive letter or UNC path. When the menu pops-up, click 
	on the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Properties</I
></SPAN
> entry at the bottom of 
	the menu. This brings up the file properties dialog
	box. Click on the tab <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Security</I
></SPAN
> and you 
	will see three buttons, <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Permissions</I
></SPAN
>, 	
	<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Auditing</I
></SPAN
>, and <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Ownership</I
></SPAN
>. 
	The <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Auditing</I
></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 which is intended to allow an 
	Administrator to add auditing requirements to a file if the 
	user is logged on as the NT Administrator. This dialog is 
	non-functional with a Samba share at this time, as the only 
	useful button, the <B
CLASS="COMMAND"
>Add</B
> button will not currently 
	allow a list of users to be seen.</P
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1550"
>11.3. Viewing file ownership</A
></H1
><P
>Clicking on the <B
CLASS="COMMAND"
>"Ownership"</B
> button 
	brings up a dialog box telling you who owns the given file. The 
	owner name will be of the form :</P
><P
><B
CLASS="COMMAND"
>"SERVER\user (Long name)"</B
></P
><P
>Where <VAR
CLASS="REPLACEABLE"
>SERVER</VAR
> is the NetBIOS name of 
	the Samba server, <VAR
CLASS="REPLACEABLE"
>user</VAR
> is the user name of 
	the UNIX user who owns the file, and <VAR
CLASS="REPLACEABLE"
>(Long name)</VAR
>
	is the descriptive string identifying the user (normally found in the
	GECOS field of the UNIX password database). Click on the <B
CLASS="COMMAND"
>Close
	</B
> button to remove this dialog.</P
><P
>If the parameter <VAR
CLASS="PARAMETER"
>nt acl support</VAR
>
	is set to <CODE
CLASS="CONSTANT"
>false</CODE
> then the file owner will 
	be shown as the NT user <B
CLASS="COMMAND"
>"Everyone"</B
>.</P
><P
>The <B
CLASS="COMMAND"
>Take Ownership</B
> button will not allow 
	you to change the ownership of this file to yourself (clicking on 
	it will display a dialog box complaining that the user you are 
	currently logged onto the NT client cannot be found). The reason 
	for this is that changing the ownership of a file is a privileged 
	operation in UNIX, available only to the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>root</I
></SPAN
> 
	user. As clicking on this button causes NT to attempt to change 
	the ownership of a file to the current user logged into the NT 
	client this will not work with Samba at this time.</P
><P
>There is an NT chown command that will work with Samba 
	and allow a user with Administrator privilege connected 
	to a Samba 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 <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Seclib
	</I
></SPAN
> NT security library written by Jeremy Allison of 
	the Samba Team, available from the main Samba ftp site.</P
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1570"
>11.4. Viewing file or directory permissions</A
></H1
><P
>The third button is the <B
CLASS="COMMAND"
>"Permissions"</B
> 
	button. Clicking on this brings up a dialog box that shows both 
	the permissions and the UNIX owner of the file or directory. 
	The owner is displayed in the form :</P
><P
><B
CLASS="COMMAND"
>"SERVER\user (Long name)"</B
></P
><P
>Where <VAR
CLASS="REPLACEABLE"
>SERVER</VAR
> is the NetBIOS name of 
	the Samba server, <VAR
CLASS="REPLACEABLE"
>user</VAR
> is the user name of 
	the UNIX user who owns the file, and <VAR
CLASS="REPLACEABLE"
>(Long name)</VAR
>
	is the descriptive string identifying the user (normally found in the
	GECOS field of the UNIX password database).</P
><P
>If the parameter <VAR
CLASS="PARAMETER"
>nt acl support</VAR
>
	is set to <CODE
CLASS="CONSTANT"
>false</CODE
> then the file owner will 
	be shown as the NT user <B
CLASS="COMMAND"
>"Everyone"</B
> and the 
	permissions will be shown as NT "Full Control".</P
><P
>The permissions field is displayed differently for files 
	and directories, so I'll describe the way file permissions 
	are displayed first.</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1585"
>11.4.1. File Permissions</A
></H2
><P
>The standard UNIX user/group/world triple and 
		the corresponding "read", "write", "execute" permissions 
		triples are mapped by Samba into a three element NT ACL 
		with the 'r', 'w', and 'x' bits mapped into the corresponding 
		NT permissions. The UNIX world permissions are mapped into 
		the global NT group <B
CLASS="COMMAND"
>Everyone</B
>, followed 
		by the list of permissions allowed for UNIX world. The UNIX 
		owner and group permissions are displayed as an NT 
		<B
CLASS="COMMAND"
>user</B
> icon and an NT <B
CLASS="COMMAND"
>local 
		group</B
> icon respectively followed by the list 
	 	of permissions allowed for the UNIX user and group.</P
><P
>As many UNIX permission sets don't map into common 
		NT names such as <B
CLASS="COMMAND"
>"read"</B
>, <B
CLASS="COMMAND"
>		"change"</B
> or <B
CLASS="COMMAND"
>"full control"</B
> then 
		usually the permissions will be prefixed by the words <B
CLASS="COMMAND"
>		"Special Access"</B
> in the NT display list.</P
><P
>But what happens if the file has no permissions allowed 
		for a particular UNIX user group or world component ? In order 
		to  allow "no permissions" to be seen and modified then Samba 
		overloads the NT <B
CLASS="COMMAND"
>"Take Ownership"</B
> ACL attribute 
		(which has no meaning in UNIX) and reports a component with 
		no permissions as having the NT <B
CLASS="COMMAND"
>"O"</B
> bit set. 
		This was chosen of course to make it look like a zero, meaning 
		zero permissions. More details on the decision behind this will 
		be given below.</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN1599"
>11.4.2. Directory Permissions</A
></H2
><P
>Directories on an NT NTFS file system have two 
		different sets of permissions. The first set of permissions 
		is the ACL set on the directory itself, this is usually displayed 
		in the first set of parentheses in the normal <B
CLASS="COMMAND"
>"RW"</B
> 
		NT style. This first set of permissions is created by Samba in 
		exactly the same way as normal file permissions are, described 
		above, and is displayed in the same way.</P
><P
>The second set of directory permissions has no real meaning 
		in the UNIX permissions world and represents the <B
CLASS="COMMAND"
>		"inherited"</B
> permissions that any file created within 
		this directory would inherit.</P
><P
>Samba synthesises these inherited permissions for NT by 
		returning as an NT ACL the UNIX permission mode that a new file 
		created by Samba on this share would receive.</P
></DIV
></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN1606"
>11.5. Modifying file or directory permissions</A
></H1
><P
>Modifying file and directory permissions is as simple 
	as changing the displayed permissions in the dialog box, and 
	clicking the <B
CLASS="COMMAND"
>OK</B
> button. However, there are 
	limitations that a user needs to be aware of, and also interactions 
	with the standard Samba permission masks and mapping of DOS 
	attributes that need to also be taken into account.</P
><P
>If the parameter <VAR
CLASS="PARAMETER"
>nt acl support</VAR
>
	is set to <CODE
CLASS="CONSTANT"
>false</CODE
> then any attempt to set 
	security permissions will fail with an <B
CLASS="COMMAND"
>"Access Denied"
	</B
> message.</P
><P
>The first thing to note is that the <B
CLASS="COMMAND"
>"Add"</B
> 
	button will not return a list of users in Samba (it will give 
	an error message of <B
CLASS="COMMAND"