1<?xml version='1.0'?>
2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
5
6<refentry id="systemd-ask-password"
7    xmlns:xi="http://www.w3.org/2001/XInclude">
8
9  <refentryinfo>
10    <title>systemd-ask-password</title>
11    <productname>systemd</productname>
12  </refentryinfo>
13
14  <refmeta>
15    <refentrytitle>systemd-ask-password</refentrytitle>
16    <manvolnum>1</manvolnum>
17  </refmeta>
18
19  <refnamediv>
20    <refname>systemd-ask-password</refname>
21    <refpurpose>Query the user for a system password</refpurpose>
22  </refnamediv>
23
24  <refsynopsisdiv>
25    <cmdsynopsis>
26      <command>systemd-ask-password <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="opt">MESSAGE</arg></command>
27    </cmdsynopsis>
28  </refsynopsisdiv>
29
30  <refsect1>
31    <title>Description</title>
32
33    <para><command>systemd-ask-password</command> may be used to query
34    a system password or passphrase from the user, using a question
35    message specified on the command line. When run from a TTY it will
36    query a password on the TTY and print it to standard output. When
37    run with no TTY or with <option>--no-tty</option> it will use the
38    system-wide query mechanism, which allows active users to respond via
39    several agents, listed below.</para>
40
41    <para>The purpose of this tool is to query system-wide passwords
42    — that is passwords not attached to a specific user account.
43    Examples include: unlocking encrypted hard disks when they are
44    plugged in or at boot, entering an SSL certificate passphrase for
45    web and VPN servers.</para>
46
47    <para>Existing agents are:
48    <itemizedlist>
49
50      <listitem><para>A boot-time password agent asking the user for
51      passwords using
52      <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
53      </para></listitem>
54
55      <listitem><para>A boot-time password agent querying the user
56      directly on the console —
57      <citerefentry><refentrytitle>systemd-ask-password-console.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
58      </para></listitem>
59
60      <listitem><para>An agent requesting password input via a
61      <citerefentry project='man-pages'><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
62      message —
63      <citerefentry><refentrytitle>systemd-ask-password-wall.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
64      </para></listitem>
65
66      <listitem><para>A TTY agent that is temporarily spawned during
67      <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
68      invocations,</para></listitem>
69
70      <listitem><para>A command line agent which can be started
71      temporarily to process queued password
72      requests — <command>systemd-tty-ask-password-agent --query</command>.
73      </para></listitem>
74    </itemizedlist></para>
75
76    <para>Answering system-wide password queries is a privileged operation, hence
77    all the agents listed above (except for the last one), run as privileged
78    system services. The last one also needs elevated privileges, so
79    should be run through
80    <citerefentry project='die-net'><refentrytitle>sudo</refentrytitle><manvolnum>8</manvolnum></citerefentry>
81    or similar.</para>
82
83    <para>Additional password agents may be implemented according to
84    the <ulink url="https://systemd.io/PASSWORD_AGENTS/">systemd Password Agent
85    Specification</ulink>.</para>
86
87    <para>If a password is queried on a TTY, the user may press TAB to
88    hide the asterisks normally shown for each character typed.
89    Pressing Backspace as first key achieves the same effect.</para>
90
91  </refsect1>
92
93  <refsect1>
94    <title>Options</title>
95
96    <para>The following options are understood:</para>
97
98    <variablelist>
99      <varlistentry>
100        <term><option>--icon=</option></term>
101
102        <listitem><para>Specify an icon name alongside the password
103        query, which may be used in all agents supporting graphical
104        display. The icon name should follow the <ulink
105        url="http://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html">XDG
106        Icon Naming Specification</ulink>.</para></listitem>
107      </varlistentry>
108
109      <varlistentry>
110        <term><option>--id=</option></term>
111        <listitem><para>Specify an identifier for this password
112        query. This identifier is freely choosable and allows
113        recognition of queries by involved agents. It should include
114        the subsystem doing the query and the specific object the
115        query is done for. Example:
116        <literal>--id=cryptsetup:/dev/sda5</literal>.</para></listitem>
117      </varlistentry>
118
119      <varlistentry>
120        <term><option>--keyname=</option></term>
121        <listitem><para>Configure a kernel keyring key name to use as
122        cache for the password. If set, then the tool will try to push
123        any collected passwords into the kernel keyring of the root
124        user, as a key of the specified name. If combined with
125        <option>--accept-cached</option>, it will also try to retrieve
126        such cached passwords from the key in the kernel keyring
127        instead of querying the user right away. By using this option,
128        the kernel keyring may be used as effective cache to avoid
129        repeatedly asking users for passwords, if there are multiple
130        objects that may be unlocked with the same password. The
131        cached key will have a timeout of 2.5min set, after which it
132        will be purged from the kernel keyring. Note that it is
133        possible to cache multiple passwords under the same keyname,
134        in which case they will be stored as <constant>NUL</constant>-separated list of
135        passwords. Use
136        <citerefentry project='die-net'><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
137        to access the cached key via the kernel keyring
138        directly. Example: <literal>--keyname=cryptsetup</literal></para></listitem>
139      </varlistentry>
140
141      <varlistentry>
142        <term><option>--credential=</option></term>
143        <listitem><para>Configure a credential to read the password from – if it exists. This may be used in
144        conjunction with the <varname>LoadCredential=</varname> and <varname>SetCredential=</varname>
145        settings in unit files. See
146        <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
147        details. If not specified, defaults to <literal>password</literal>. This option has no effect if no
148        credentials directory is passed to the program (i.e. <varname>$CREDENTIALS_DIRECTORY</varname> is not
149        set) or if the no credential of the specified name exists.</para></listitem>
150      </varlistentry>
151
152      <varlistentry>
153        <term><option>--timeout=</option></term>
154
155        <listitem><para>Specify the query timeout in seconds. Defaults
156        to 90s. A timeout of 0 waits indefinitely. </para></listitem>
157      </varlistentry>
158
159      <varlistentry>
160        <term><option>--echo=yes|no|masked</option></term>
161
162        <listitem><para>Controls whether to echo user input. Takes a boolean or the special string
163        <literal>masked</literal>, the default being the latter. If enabled the typed characters are echoed
164        literally, which is useful for prompting for usernames and other non-protected data. If disabled the
165        typed characters are not echoed in any form, the user will not get feedback on their input. If set to
166        <literal>masked</literal>, an asterisk (<literal>*</literal>) is echoed for each character
167        typed. In this mode, if the user hits the tabulator key (<literal>↹</literal>), echo is turned
168        off. (Alternatively, if the user hits the backspace key (<literal>⌫</literal>) while no data has
169        been entered otherwise, echo is turned off, too).</para></listitem>
170      </varlistentry>
171
172      <varlistentry>
173        <term><option>--echo</option></term>
174        <term><option>-e</option></term>
175
176        <listitem><para>Equivalent to <option>--echo=yes</option>, see above.</para></listitem>
177      </varlistentry>
178
179      <varlistentry>
180        <term><option>--emoji=yes|no|auto</option></term>
181
182        <listitem><para>Controls whether or not to prefix the query with a
183        lock and key emoji (��), if the TTY settings permit this. The default
184        is <literal>auto</literal>, which defaults to <literal>yes</literal>,
185        unless <option>--echo=yes</option> is given.</para></listitem>
186      </varlistentry>
187
188      <varlistentry>
189        <term><option>--no-tty</option></term>
190
191        <listitem><para>Never ask for password on current TTY even if
192        one is available. Always use agent system.</para></listitem>
193      </varlistentry>
194
195      <varlistentry>
196        <term><option>--accept-cached</option></term>
197
198        <listitem><para>If passed, accept cached passwords, i.e.
199        passwords previously entered.</para></listitem>
200      </varlistentry>
201
202      <varlistentry>
203        <term><option>--multiple</option></term>
204
205        <listitem><para>When used in conjunction with
206        <option>--accept-cached</option> accept multiple passwords.
207        This will output one password per line.</para></listitem>
208      </varlistentry>
209
210      <varlistentry>
211        <term><option>--no-output</option></term>
212
213        <listitem><para>Do not print passwords to standard output.  This is useful if you want to store a
214        password in kernel keyring with <option>--keyname=</option> but do not want it to show up on screen
215        or in logs.</para></listitem>
216      </varlistentry>
217
218      <varlistentry>
219        <term><option>-n</option></term>
220
221        <listitem><para>By default, when writing the acquired password to standard output it is suffixed by a
222        newline character. This may be turned off with the <option>-n</option> switch, similar to the switch
223        of the same name of the <citerefentry
224        project='man-pages'><refentrytitle>echo</refentrytitle><manvolnum>1</manvolnum></citerefentry>
225        command.</para></listitem>
226      </varlistentry>
227
228      <xi:include href="standard-options.xml" xpointer="help" />
229    </variablelist>
230
231  </refsect1>
232
233  <refsect1>
234    <title>Exit status</title>
235
236    <para>On success, 0 is returned, a non-zero failure code
237    otherwise.</para>
238  </refsect1>
239
240  <refsect1>
241    <title>See Also</title>
242    <para>
243      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
244      <citerefentry><refentrytitle>systemd-ask-password-console.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
245      <citerefentry><refentrytitle>systemd-tty-ask-password-agent</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
246      <citerefentry project='die-net'><refentrytitle>keyctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
247      <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
248      <citerefentry project='man-pages'><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
249    </para>
250  </refsect1>
251
252</refentry>
253