source: postlfs/security/linux-pam.xml

trunk
Last change on this file was 2773977, checked in by Xi Ruoyao <xry111@…>, 2 days ago

linux-pam: Get rid of rpath
  • Property mode set to 100644
File size: 19.7 KB
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1<?xml version="1.0" encoding="UTF-8"?>
2<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4 <!ENTITY % general-entities SYSTEM "../../general.ent">
5 %general-entities;
6
7 <!ENTITY linux-pam-download-http "https://github.com/linux-pam/linux-pam/releases/download/v&linux-pam-version;/Linux-PAM-&linux-pam-version;.tar.xz">
8 <!ENTITY linux-pam-download-ftp " ">
9 <!ENTITY linux-pam-md5sum "8ad1e72d1ff6480d8e0af658e2d7b768">
10 <!ENTITY linux-pam-size "1.0 MB">
11 <!ENTITY linux-pam-buildsize "39 MB (with tests)">
12 <!ENTITY linux-pam-time "0.4 SBU (with tests)">
13
14 <!ENTITY linux-pam-docs-download "https://github.com/linux-pam/linux-pam/releases/download/v&linux-pam-version;/Linux-PAM-&linux-pam-docs-version;-docs.tar.xz">
15 <!ENTITY linux-pam-docs-md5sum "46dc9f9a27ef73a2fbe3b667877e88da">
16 <!ENTITY linux-pam-docs-size "455 KB">
17 <!--
18 <!ENTITY debian-pam-docs "http://debian.securedservers.com/kernel/pub/linux/libs/pam">
19 -->
20]>
21
22<sect1 id="linux-pam" xreflabel="Linux-PAM-&linux-pam-version;">
23 <?dbhtml filename="linux-pam.html"?>
24
25
26 <title>Linux-PAM-&linux-pam-version;</title>
27
28 <indexterm zone="linux-pam">
29 <primary sortas="a-Linux-PAM">Linux-PAM</primary>
30 </indexterm>
31
32 <sect2 role="package">
33 <title>Introduction to Linux PAM</title>
34
35 <para>
36 The <application>Linux PAM</application> package contains
37 Pluggable Authentication Modules used by the local
38 system administrator to control how application programs authenticate
39 users.
40 </para>
41
42 &lfs121_checked;
43
44 <bridgehead renderas="sect3">Package Information</bridgehead>
45 <itemizedlist spacing="compact">
46 <listitem>
47 <para>
48 Download (HTTP): <ulink url="&linux-pam-download-http;"/>
49 </para>
50 </listitem>
51 <listitem>
52 <para>
53 Download (FTP): <ulink url="&linux-pam-download-ftp;"/>
54 </para>
55 </listitem>
56 <listitem>
57 <para>
58 Download MD5 sum: &linux-pam-md5sum;
59 </para>
60 </listitem>
61 <listitem>
62 <para>
63 Download size: &linux-pam-size;
64 </para>
65 </listitem>
66 <listitem>
67 <para>
68 Estimated disk space required: &linux-pam-buildsize;
69 </para>
70 </listitem>
71 <listitem>
72 <para>
73 Estimated build time: &linux-pam-time;
74 </para>
75 </listitem>
76 </itemizedlist>
77
78 <bridgehead renderas="sect3">Additional Downloads</bridgehead>
79 <itemizedlist spacing="compact">
80 <title>Optional Documentation</title>
81 <listitem>
82 <para>
83 Download (HTTP): <ulink url="&linux-pam-docs-download;"/>
84 </para>
85 </listitem>
86 <listitem>
87 <para>
88 Download MD5 sum: &linux-pam-docs-md5sum;
89 </para>
90 </listitem>
91 <listitem>
92 <para>
93 Download size: &linux-pam-docs-size;
94 </para>
95 </listitem>
96 </itemizedlist>
97
98 <bridgehead renderas="sect3">Linux PAM Dependencies</bridgehead>
99
100 <bridgehead renderas="sect4">Optional</bridgehead>
101 <para role="optional">
102 <xref linkend="libnsl"/>,
103 <xref linkend="libtirpc"/>,
104 <xref linkend="rpcsvc-proto"/>,
105 &berkeley-db;,
106 <ulink url="https://github.com/linux-audit/audit-userspace">libaudit</ulink>,
107 <ulink url="https://github.com/openSUSE/libeconf">libeconf</ulink>, and
108 <ulink url="https://www.prelude-siem.org">Prelude</ulink>
109 </para>
110<!-- With 1.5.3, building the doc requires the namespaced version of
111 docbook-xsl, which is beyond BLFS.
112
113 <bridgehead renderas="sect4">Optional (To Rebuild the Documentation)</bridgehead>
114 <para role="optional">
115 <xref linkend="DocBook"/>,
116 <xref linkend="docbook-xsl"/>,
117 <xref linkend="fop"/>,
118 <xref linkend="libxslt"/> and either
119 <xref linkend="lynx"/> or
120 <ulink url="&w3m-url;">W3m</ulink>
121 </para>
122-->
123 <note>
124 <para role="required">
125 <xref role="runtime" linkend="shadow"/>
126 <phrase revision="systemd"> and <xref role="runtime" linkend="systemd"/>
127 must</phrase><phrase revision="sysv">must</phrase> be reinstalled
128 and reconfigured
129 after installing and configuring <application>Linux PAM</application>.
130 </para>
131
132 <para role="recommended">
133 With Linux-PAM-1.4.0 and higher, the pam_cracklib module is not
134 installed by default. Use <xref role="runtime" linkend="libpwquality"/>
135 to enforce strong passwords.
136 </para>
137 </note>
138
139 </sect2>
140
141 <sect2 role="kernel" id="linux-pam-kernel">
142 <title>Kernel Configuration</title>
143
144 <para>
145 For the PAM module <filename
146 class='libraryfile'>pam_loginuid.so</filename> (referred by
147 the PAM configuration file <filename>system-session</filename> if
148 <phrase revision='sysv'><xref linkend='elogind'/> is
149 built</phrase><phrase revision='systemd'><xref linkend='systemd'/> is
150 rebuilt with PAM support</phrase> later) to work,
151 a kernel configuration parameter need to be set or the module will
152 just do nothing:
153 </para>
154
155 <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
156 href="linux-pam-kernel.xml"/>
157
158 <indexterm zone="linux-pam linux-pam-kernel">
159 <primary sortas="d-linux-pam">Linux-PAM</primary>
160 </indexterm>
161
162 </sect2>
163
164 <sect2 role="installation">
165 <title>Installation of Linux PAM</title>
166
167 <para revision="sysv">
168 First, prevent the installation of an unneeded systemd file:
169 </para>
170
171<screen revision="sysv"><userinput>sed -e /service_DATA/d \
172 -i modules/pam_namespace/Makefile.am</userinput></screen>
173
174 <!-- https://github.com/linux-pam/linux-pam/issues/809 -->
175 <para>
176 The shipped <filename>libtool.m4</filename> file has a configuration
177 inconsistent with LFS <filename class='directory'>/usr</filename>
178 hierarchy. This issue would cause
179 <filename class='libraryfile'>libpam_misc.so</filename> linked with
180 an rpath flag which may sometimes cause troubles or even security
181 issues. Regenerate the building system to fix the inconsistency:
182 </para>
183
184<screen><userinput>autoreconf -fi</userinput></screen>
185
186 <para>
187 If you downloaded the documentation, unpack the tarball by issuing
188 the following command.
189 </para>
190
191<screen><userinput>tar -xf ../Linux-PAM-&linux-pam-docs-version;-docs.tar.xz --strip-components=1</userinput></screen>
192<!--
193 <para>
194 If you want to regenerate the documentation yourself, fix the
195 <command>configure</command> script so it will detect lynx:
196 </para>
197
198<screen><userinput>sed -e 's/dummy elinks/dummy lynx/' \
199 -e 's/-no-numbering -no-references/-force-html -nonumbers -stdin/' \
200 -i configure</userinput></screen>
201-->
202 <para>
203 Compile and link <application>Linux PAM</application> by
204 running the following commands:
205 </para>
206
207<screen><userinput>./configure --prefix=/usr \
208 --sbindir=/usr/sbin \
209 --sysconfdir=/etc \
210 --libdir=/usr/lib \
211 --enable-securedir=/usr/lib/security \
212 --docdir=/usr/share/doc/Linux-PAM-&linux-pam-version; &amp;&amp;
213make</userinput></screen>
214
215 <para>
216 To test the results, a suitable <filename>/etc/pam.d/other</filename>
217 configuration file must exist.
218 </para>
219
220 <caution>
221 <title>Reinstallation or Upgrade of Linux PAM</title>
222 <para>
223 If you have a system with Linux PAM installed and working, be careful
224 when modifying the files in
225 <filename class="directory">/etc/pam.d</filename>, since your system
226 may become totally unusable. If you want to run the tests, you do not
227 need to create another <filename>/etc/pam.d/other</filename> file. The
228 existing file can be used for the tests.
229 </para>
230
231 <para>
232 You should also be aware that <command>make install</command>
233 overwrites the configuration files in
234 <filename class="directory">/etc/security</filename> as well as
235 <filename>/etc/environment</filename>. If you
236 have modified those files, be sure to back them up.
237 </para>
238 </caution>
239
240 <para>
241 For a first-time installation, create a configuration file by issuing the
242 following commands as the <systemitem class="username">root</systemitem>
243 user:
244 </para>
245
246<screen role="root"><userinput>install -v -m755 -d /etc/pam.d &amp;&amp;
247
248cat &gt; /etc/pam.d/other &lt;&lt; "EOF"
249<literal>auth required pam_deny.so
250account required pam_deny.so
251password required pam_deny.so
252session required pam_deny.so</literal>
253EOF</userinput></screen>
254
255 <para>
256 Now run the tests by issuing <command>make check</command>.
257 Be sure the tests produced no errors before continuing the
258 installation. Note that the tests are very long.
259 Redirect the output to a log file, so you can inspect it thoroughly.
260 </para>
261
262 <para>
263 For a first-time installation, remove the configuration file
264 created earlier by issuing the following command as the
265 <systemitem class="username">root</systemitem> user:
266 </para>
267
268<screen role="root"><userinput>rm -fv /etc/pam.d/other</userinput></screen>
269
270 <para>
271 Now, as the <systemitem class="username">root</systemitem>
272 user:
273 </para>
274
275<screen role="root"><userinput>make install &amp;&amp;
276chmod -v 4755 /usr/sbin/unix_chkpwd</userinput></screen>
277
278 </sect2>
279
280 <sect2 role="commands">
281 <title>Command Explanations</title>
282
283 <para>
284 <parameter>--enable-securedir=/usr/lib/security</parameter>:
285 This switch sets the installation location for the
286 <application>PAM</application> modules.
287 </para>
288<!--
289 <para>
290 <option>- -disable-regenerate-docu</option> : If the needed dependencies
291 (<xref linkend="DocBook"/>, <xref linkend="docbook-xsl"/>, <xref
292 linkend="libxslt"/>, and <xref linkend="lynx"/> or <ulink
293 url="&w3m-url;">W3m</ulink>) are installed, the manual pages, and the
294 html and text documentation files, are generated and installed.
295 Furthermore, if <xref linkend="fop"/> is installed, the PDF
296 documentation is generated and installed. Use this switch if you do not
297 want to rebuild the documentation.
298 </para>
299-->
300 <para>
301 <command>chmod -v 4755 /usr/sbin/unix_chkpwd</command>:
302 The setuid bit for the <command>unix_chkpwd</command> helper program must be
303 turned on, so that non-<systemitem class="username">root</systemitem>
304 processes can access the shadow file.
305 </para>
306
307 </sect2>
308
309 <sect2 role="configuration">
310 <title>Configuring Linux-PAM</title>
311
312 <sect3 id="pam-config">
313 <title>Configuration Files</title>
314
315 <para>
316 <filename>/etc/security/*</filename> and
317 <filename>/etc/pam.d/*</filename>
318 </para>
319
320 <indexterm zone="linux-pam pam-config">
321 <primary sortas="e-etc-security">/etc/security/*</primary>
322 </indexterm>
323
324 <indexterm zone="linux-pam pam-config">
325 <primary sortas="e-etc-pam.d">/etc/pam.d/*</primary>
326 </indexterm>
327
328 </sect3>
329
330 <sect3>
331 <title>Configuration Information</title>
332
333 <para>
334 Configuration information is placed in
335 <filename class="directory">/etc/pam.d/</filename>.
336 Here is a sample file:
337 </para>
338
339<screen><literal># Begin /etc/pam.d/other
340
341auth required pam_unix.so nullok
342account required pam_unix.so
343session required pam_unix.so
344password required pam_unix.so nullok
345
346# End /etc/pam.d/other</literal></screen>
347
348 <para>
349 Now create some generic configuration files. As the
350 <systemitem class="username">root</systemitem> user:
351 </para>
352
353<screen role="root"><userinput>install -vdm755 /etc/pam.d &amp;&amp;
354cat &gt; /etc/pam.d/system-account &lt;&lt; "EOF" &amp;&amp;
355<literal># Begin /etc/pam.d/system-account
356
357account required pam_unix.so
358
359# End /etc/pam.d/system-account</literal>
360EOF
361
362cat &gt; /etc/pam.d/system-auth &lt;&lt; "EOF" &amp;&amp;
363<literal># Begin /etc/pam.d/system-auth
364
365auth required pam_unix.so
366
367# End /etc/pam.d/system-auth</literal>
368EOF
369
370cat &gt; /etc/pam.d/system-session &lt;&lt; "EOF" &amp;&amp;
371<literal># Begin /etc/pam.d/system-session
372
373session required pam_unix.so
374
375# End /etc/pam.d/system-session</literal>
376EOF
377
378cat &gt; /etc/pam.d/system-password &lt;&lt; "EOF"
379<literal># Begin /etc/pam.d/system-password
380
381# use yescrypt hash for encryption, use shadow, and try to use any
382# previously defined authentication token (chosen password) set by any
383# prior module.
384password required pam_unix.so yescrypt shadow try_first_pass
385
386# End /etc/pam.d/system-password</literal>
387EOF
388</userinput></screen>
389
390 <para>
391 If you wish to enable strong password support, install
392 <xref linkend="libpwquality"/>, and follow the
393 instructions on that page to configure the pam_pwquality
394 PAM module with strong password support.
395 </para>
396
397 <para>
398 Next, add a restrictive <filename>/etc/pam.d/other</filename>
399 configuration file. With this file, programs that are PAM aware will
400 not run unless a configuration file specifically for that application
401 exists.
402 </para>
403
404<screen role="root"><userinput>cat &gt; /etc/pam.d/other &lt;&lt; "EOF"
405<literal># Begin /etc/pam.d/other
406
407auth required pam_warn.so
408auth required pam_deny.so
409account required pam_warn.so
410account required pam_deny.so
411password required pam_warn.so
412password required pam_deny.so
413session required pam_warn.so
414session required pam_deny.so
415
416# End /etc/pam.d/other</literal>
417EOF</userinput></screen>
418
419 <para>
420 The <application>PAM</application> man page (<command>man
421 pam</command>) provides a good starting point to learn
422 about the several fields, and allowable entries.
423 <!-- not accessible 2022-09-08 -->
424 <!-- it's available at a different address 2022-10-23-->
425 The
426 <ulink url="https://www.docs4dev.com/docs/en/linux-pam/1.1.2/reference/Linux-PAM_SAG.html">
427 Linux-PAM System Administrators' Guide
428 </ulink> is recommended for additional information.
429 </para>
430
431 <important>
432 <para>
433 You should now reinstall the <xref linkend="shadow"/>
434 <phrase revision="sysv">package</phrase>
435 <phrase revision="systemd"> and <xref linkend="systemd"/>
436 packages</phrase>.
437 </para>
438 </important>
439
440 </sect3>
441
442 </sect2>
443
444 <sect2 role="content">
445 <title>Contents</title>
446
447 <segmentedlist>
448 <segtitle>Installed Program</segtitle>
449 <segtitle>Installed Libraries</segtitle>
450 <segtitle>Installed Directories</segtitle>
451
452 <seglistitem>
453 <seg>
454 faillock, mkhomedir_helper, pam_namespace_helper,
455 pam_timestamp_check, pwhistory_helper, unix_chkpwd and
456 unix_update
457 </seg>
458 <seg>
459 libpam.so, libpamc.so and libpam_misc.so
460 </seg>
461 <seg>
462 /etc/security,
463 /usr/lib/security,
464 /usr/include/security and
465 /usr/share/doc/Linux-PAM-&linux-pam-version;
466 </seg>
467 </seglistitem>
468 </segmentedlist>
469
470 <variablelist>
471 <bridgehead renderas="sect3">Short Descriptions</bridgehead>
472 <?dbfo list-presentation="list"?>
473 <?dbhtml list-presentation="table"?>
474
475 <varlistentry id="faillock">
476 <term><command>faillock</command></term>
477 <listitem>
478 <para>
479 displays and modifies the authentication failure record files
480 </para>
481 <indexterm zone="linux-pam faillock">
482 <primary sortas="b-faillock">faillock</primary>
483 </indexterm>
484 </listitem>
485 </varlistentry>
486
487 <varlistentry id="mkhomedir_helper">
488 <term><command>mkhomedir_helper</command></term>
489 <listitem>
490 <para>
491 is a helper binary that creates home directories
492 </para>
493 <indexterm zone="linux-pam mkhomedir_helper">
494 <primary sortas="b-mkhomedir_helper">mkhomedir_helper</primary>
495 </indexterm>
496 </listitem>
497 </varlistentry>
498
499 <varlistentry id="pam_namespace_helper">
500 <term><command>pam_namespace_helper</command></term>
501 <listitem>
502 <para>
503 is a helper program used to configure a private namespace for a
504 user session
505 </para>
506 <indexterm zone="linux-pam pam_namespace_helper">
507 <primary sortas="b-pam_namespace_helper">pam_namespace_helper</primary>
508 </indexterm>
509 </listitem>
510 </varlistentry>
511
512 <varlistentry id="pwhistory_helper">
513 <term><command>pwhistory_helper</command></term>
514 <listitem>
515 <para>
516 is a helper program that transfers password hashes from passwd or
517 shadow to opasswd
518 </para>
519 <indexterm zone="linux-pam pwhistory_helper">
520 <primary sortas="b-pwhistory_helper">pwhistory_helper</primary>
521 </indexterm>
522 </listitem>
523 </varlistentry>
524<!-- Removed with the removal of the pam_tally{,2} module
525 <varlistentry id="pam_tally">
526 <term><command>pam_tally</command></term>
527 <listitem>
528 <para>
529 is used to interrogate and manipulate the login counter file.
530 </para>
531 <indexterm zone="linux-pam pam_tally">
532 <primary sortas="b-pam_tally">pam_tally</primary>
533 </indexterm>
534 </listitem>
535 </varlistentry>
536
537 <varlistentry id="pam_tally2">
538 <term><command>pam_tally2</command></term>
539 <listitem>
540 <para>
541 is used to interrogate and manipulate the login counter file, but
542 does not have some limitations that <command>pam_tally</command>
543 does.
544 </para>
545 <indexterm zone="linux-pam pam_tally2">
546 <primary sortas="b-pam_tally2">pam_tally2</primary>
547 </indexterm>
548 </listitem>
549 </varlistentry>
550-->
551
552 <varlistentry id="pam_timestamp_check">
553 <term><command>pam_timestamp_check</command></term>
554 <listitem>
555 <para>
556 is used to check if the default timestamp is valid
557 </para>
558 <indexterm zone="linux-pam pam_timestamp_check">
559 <primary sortas="b-pam_timestamp_check">pam_timestamp_check</primary>
560 </indexterm>
561 </listitem>
562 </varlistentry>
563
564 <varlistentry id="unix_chkpwd">
565 <term><command>unix_chkpwd</command></term>
566 <listitem>
567 <para>
568 is a helper binary that verifies the password of the current user
569 </para>
570 <indexterm zone="linux-pam unix_chkpwd">
571 <primary sortas="b-unix_chkpwd">unix_chkpwd</primary>
572 </indexterm>
573 </listitem>
574 </varlistentry>
575
576 <varlistentry id="unix_update">
577 <term><command>unix_update</command></term>
578 <listitem>
579 <para>
580 is a helper binary that updates the password of a given user
581 </para>
582 <indexterm zone="linux-pam unix_update">
583 <primary sortas="b-unix_update">unix_update</primary>
584 </indexterm>
585 </listitem>
586 </varlistentry>
587
588 <varlistentry id="libpam">
589 <term><filename class="libraryfile">libpam.so</filename></term>
590 <listitem>
591 <para>
592 provides the interfaces between applications and the
593 PAM modules
594 </para>
595 <indexterm zone="linux-pam libpam">
596 <primary sortas="c-libpam">libpam.so</primary>
597 </indexterm>
598 </listitem>
599 </varlistentry>
600
601 </variablelist>
602
603 </sect2>
604
605</sect1>
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