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diff --git a/doc/tdesu/index.docbook b/doc/tdesu/index.docbook new file mode 100644 index 000000000..81c71cf17 --- /dev/null +++ b/doc/tdesu/index.docbook @@ -0,0 +1,320 @@ +<?xml version="1.0" ?> +<!DOCTYPE book PUBLIC "-//KDE//DTD DocBook XML V4.2-Based Variant V1.1//EN" +"dtd/kdex.dtd" [ + <!ENTITY kappname "&tdesu;"> + <!ENTITY package "kdebase"> + <!ENTITY % addindex "IGNORE"> + <!ENTITY % English "INCLUDE" > <!-- change language only here --> +]> + +<book lang="&language;"> +<bookinfo> + +<title>The &tdesu; handbook</title> + +<authorgroup> +<author>&Geert.Jansen; &Geert.Jansen.mail;</author> +<!-- TRANS:ROLES_OF_TRANSLATORS --> +</authorgroup> + +<copyright> +<year>2000</year> +<holder>&Geert.Jansen;</holder> +</copyright> + +<legalnotice>&FDLNotice;</legalnotice> + +<date>2005-06-07</date> +<releaseinfo>1.00.00</releaseinfo> + + +<abstract><para>&tdesu; is a graphical front end for the &UNIX; +<command>su</command> command.</para></abstract> + +<keywordset> +<keyword>KDE</keyword> +<keyword>su</keyword> +<keyword>password</keyword> +<keyword>root</keyword> +</keywordset> + +</bookinfo> + +<chapter id="introduction"> +<title>Introduction</title> + +<para>Welcome to &tdesu;! &tdesu; is a graphical front end for the +&UNIX; <command>su</command> command for the K Desktop Environment. +It allows you to run a program as different user by supplying the +password for that user. &tdesu; is an unprivileged program; it uses +the system's <command>su</command>.</para> + +<para>&tdesu; has one additional feature: it can remember passwords +for you. If you are using this feature, you only need to enter the +password once for each command. See <xref +linkend="sec-password-keeping"/> for more information on this and a +security analysis.</para> + +<para>This program is meant to be started from the command line or +from <filename>.desktop</filename> files. Although it asks for the +<systemitem class="username">root</systemitem> password using a &GUI; +dialog, I consider it to be more of a command line <-> &GUI; +glue instead of a pure &GUI; program.</para> + +</chapter> + +<chapter id="using-tdesu"> +<title>Using &tdesu;</title> + +<para>Usage of &tdesu; is easy. The syntax is like this:</para> + +<cmdsynopsis> +<command>tdesu</command> + +<group choice="opt"><option>-c</option></group> +<group choice="opt"><option>-d</option></group> +<group choice="opt"><option>-f</option> <replaceable> file</replaceable></group> +<group choice="opt"><option>-i</option> <replaceable> icon name</replaceable></group> +<group choice="opt"><option>-n</option></group> +<group choice="opt"><option>-p</option> <replaceable> priority</replaceable></group> +<group choice="opt"><option>-r</option></group> +<group choice="opt"><option>-s</option></group> +<group choice="opt"><option>-t</option></group> +<group choice="opt"><option>-u</option> <replaceable> +user</replaceable></group> +<group choice="opt"><option>--nonewdcop</option></group> + +<group><arg choice="req"><replaceable>command</replaceable> <arg><replaceable>arg1</replaceable></arg> + <arg><replaceable>arg2</replaceable></arg> + <arg rep="repeat"><replaceable></replaceable></arg></arg></group> +</cmdsynopsis> +<cmdsynopsis> +<command>tdesu</command> +<arg choice="opt">&kde; Generic Options</arg> +<arg choice="opt">Qt Generic Options</arg> +</cmdsynopsis> + +<para>The command line options are explained below.</para> + +<variablelist> +<varlistentry> +<term><option>-c <replaceable>program</replaceable></option></term> +<listitem><para>This specifies the program to run as root. It has to be passed +in one argument. So if, for example, you want to start a new file manager, you +would enter at the prompt: <userinput><command>tdesu <option>-c <replaceable>kfm +-sw</replaceable></option></command></userinput></para></listitem> +</varlistentry> +<varlistentry> +<term><option>-d</option></term> +<listitem><para>Show debug information.</para></listitem> +</varlistentry> +<varlistentry> +<term><option>-f <replaceable>file</replaceable></option></term> +<listitem><para>This option allow efficient use of &tdesu; in +<filename>.desktop</filename> files. It tells &tdesu; to examine the +file specified by <parameter>file</parameter>. If this file is +writable by the current user, &tdesu; will execute the command as the +current user. If it is not writable, the command is executed as user +<parameter>user</parameter> (defaults to root).</para> +<para><parameter>file</parameter> is evaluated like this: if +<parameter>FILE</parameter> starts with a <literal>/</literal>, it is +taken as an absolute filename. Otherwise, it is taken as the name of a +global &kde; configuration file. For example: to configure the K display +manager, <application>kdm</application>, you could issue +<command>tdesu <option>-c kdmconfig -f +kdmrc</option></command></para></listitem> +</varlistentry> +<varlistentry> +<term><option>-i</option> <replaceable>icon name</replaceable></term> +<listitem><para>Specify icon to use in the password dialog. You may specify +just the name, without any extension.</para> +<para>For instance to run <command>kfmclient</command> and show the +&konqueror; icon in the password dialog:</para> +<screen><userinput><command>tdesu</command> <option>-i konqueror</option> <command>kfmclient</command></userinput></screen> +</listitem> +</varlistentry> + +<varlistentry> +<term><option>-n</option></term> +<listitem><para>Do not keep the password. This disables the <guilabel>keep +password</guilabel> checkbox in the password dialog.</para></listitem> +</varlistentry> +<varlistentry> +<term><option>-p</option> <replaceable>priority</replaceable></term> +<listitem> +<para>Set priority value. The priority is an arbitrary number between 0 and +100, where 100 means highest priority, and 0 means lowest. The default is +50.</para> +</listitem> +</varlistentry> +<varlistentry> +<term><option>-r</option></term> +<listitem><para>Use realtime scheduling.</para> +</listitem> +</varlistentry> + +<varlistentry> +<term><option>-s</option></term> +<listitem><para>Stop the tdesu daemon. See <xref +linkend="sec-password-keeping"/>.</para></listitem> +</varlistentry> +<varlistentry> +<term><option>-t</option></term> +<listitem><para>Enable terminal output. This disables password keeping. This is +largely for debugging purposes; if you want to run a console mode app, use the +standard <command>su</command> instead.</para> </listitem> +</varlistentry> +<varlistentry> +<term><option>-u</option> <replaceable> user</replaceable></term> +<listitem><para>While the most common use for &tdesu; is to run a command as +the superuser, you can supply any user name and the appropriate +password.</para> +</listitem> +</varlistentry> + +</variablelist> + +</chapter> + +<chapter id="Internals"> +<title>Internals</title> + +<sect1 id="x-authentication"> +<title>X authentication</title> + +<para>The program you execute will run under the root user id and will +generally have no authority to access your X display. &tdesu; gets +around this by adding an authentication cookie for your display to a +temporary <filename>.Xauthority</filename> file. After the command +exits, this file is removed. </para> + +<para>If you don't use X cookies, you are on your own. &tdesu; will +detect this and will not add a cookie but you will have to make sure +that root is allowed to access to your display.</para> + +</sect1> + +<sect1 id="interface-to-su"> +<title>Interface to <command>su</command></title> + +<para>&tdesu; uses the sytem's <command>su</command> for acquiring +priviliges. In this section, I explain the details of how &tdesu; does +this. </para> + +<para>Because some <command>su</command> implementations (&ie; the one +from &RedHat;) don't want to read the password from +<literal>stdin</literal>, &tdesu; creates a pty/tty pair and executes +<command>su</command> with it's standard filedescriptors connected to +the tty.</para> + +<para>To execute the command the user selected, rather than an +interactive shell, &tdesu; uses the <option>-c</option> argument with +<command>su</command>. This argument is understood by every shell that +I know of so it should work portably. <command>su</command> passes +this <option>-c</option> argument to the target user's shell, and the +shell executes the program. Example command: <command>su <option>root +-c <replaceable>the_program</replaceable></option></command>.</para> + +<para>Instead of executing the user command directly with +<command>su</command>, &tdesu; executes a little stub program called +<application>tdesu_stub</application>. This stub (running as the +target user), requests some information from &tdesu; over the pty/tty +channel (the stub's stdin and stdout) and then executes the user's +program. The information passed over is: the X display, an X +authentication cookie (if available), the <envar>PATH</envar> and the +command to run. The reason why a stub program is used is that the X +cookie is private information and therefore cannot be passed on the +command line.</para> + +</sect1> + +<sect1 id="password-checking"> +<title>Password Checking</title> + +<para>&tdesu; will check the password you entered and gives an error +message if it is not correct. The checking is done by executing a test +program: <filename>/bin/true</filename>. If this succeeds, the +password is assumed to be correct.</para> + +</sect1> + +<sect1 id="sec-password-keeping"> +<title>Password Keeping</title> + +<para>For your comfort, &tdesu; implements a <quote>keep +password</quote> feature. If you are interested in security, you +should read this paragraph.</para> + +<para>Allowing &tdesu; to remember passwords opens up a (small) +security hole in your system. Obviously, &tdesu; does not allow +anybody but your user id to use the passwords, but, if done without +caution, this would lowers <systemitem +class="username">root</systemitem>'s security level to that of a +normal user (you). A hacker who breaks into your account, would get +<systemitem class="username">root</systemitem> access. &tdesu; tries +to prevent this. The security scheme it uses is, in my opinion at +least, reasonably safe and is explained here.</para> + +<para>&tdesu; uses a daemon, called +<application>tdesud</application>. The daemon listens to a &UNIX; +socket in <filename>/tmp</filename> for commands. The mode of the +socket is 0600 so that only your user id can connect to it. If +password keeping is enabled, &tdesu; executes commands through this +daemon. It writes the command and <systemitem +class="username">root</systemitem>'s password to the socket and the +daemon executes the command using <command>su</command>, as describe +before. After this, the command and the password are not thrown +away. Instead, they are kept for a specified amount of time. This is +the timeout value from in the control module. If another request for +the same command is coming within this time period, the client does +not have to supply the password. To keep hackers who broke into your +account from stealing passwords from the daemon (for example, by +attaching a debugger), the daemon is installed set-group-id +nogroup. This should prevent all normal users (including you) from +getting passwords from the <application>tdesud</application> +process. Also, the daemon sets the <envar>DISPLAY</envar> environment +variable to the value it had when it was started. The only thing a +hacker can do is execute an application on your display.</para> + +<para>One weak spot in this scheme is that the programs you execute +are probably not written with security in mind (like setuid +<systemitem class="username">root</systemitem> programs). This means +that they might have buffer overruns or other problems and a hacker +could exploit those.</para> + +<para>The use of the password keeping feature is a tradeoff between +security and comfort. I encourage you to think it over and decide for +yourself if you want to use it or not.</para> + +</sect1> +</chapter> + +<chapter id="Author"> +<title>Author</title> + +<para>&tdesu;</para> + +<para>Copyright 2000 &Geert.Jansen;</para> + +<para>&tdesu; is written by &Geert.Jansen;. It is somewhat based on +Pietro Iglio's &tdesu;, version 0.3. Pietro and I agreed that I will +maintain this program in the future.</para> + +<para>The author can be reached through email at &Geert.Jansen.mail;. +Please report any bugs you find to me so that I can fix them. If you +have a suggestion, feel free to contact me.</para> + +&underFDL; +&underArtisticLicense; + +</chapter> + +</book> +<!-- +Local Variables: +mode: sgml +sgml-omittag: nil +sgml-shorttag: t +End: +--> + |