path: root/modules/pam_limits/pam_limits.8.xml

<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="pam_limits">

  <refmeta>
    <refentrytitle>pam_limits</refentrytitle>
    <manvolnum>8</manvolnum>
    <refmiscinfo class="source">Linux-PAM</refmiscinfo>
    <refmiscinfo class="manual">Linux-PAM Manual</refmiscinfo>
  </refmeta>

  <refnamediv xml:id="pam_limits-name">
    <refname>pam_limits</refname>
    <refpurpose>
      PAM module to limit resources
    </refpurpose>
  </refnamediv>

<!-- body begins here -->

  <refsynopsisdiv>
    <cmdsynopsis xml:id="pam_limits-cmdsynopsis" sepchar=" ">
      <command>pam_limits.so</command>
      <arg choice="opt" rep="norepeat">
        conf=<replaceable>/path/to/limits.conf</replaceable>
      </arg>
      <arg choice="opt" rep="norepeat">
        debug
      </arg>
      <arg choice="opt" rep="norepeat">
        set_all
      </arg>
      <arg choice="opt" rep="norepeat">
        utmp_early
      </arg>
      <arg choice="opt" rep="norepeat">
        noaudit
      </arg>
    </cmdsynopsis>
  </refsynopsisdiv>


  <refsect1 xml:id="pam_limits-description">
    <title>DESCRIPTION</title>
    <para>
      The pam_limits PAM module sets limits on the system resources that can be
      obtained in a user-session. Users of <emphasis>uid=0</emphasis> are affected
      by this limits, too.
    </para>
    <para condition="without_vendordir">
      By default limits are taken from the <filename>/etc/security/limits.conf</filename>
      config file. Then individual *.conf files from the <filename>/etc/security/limits.d/</filename>
      directory are read. The files are parsed one after another in the order of "C" locale.
      The effect of the individual files is the same as if all the files were
      concatenated together in the order of parsing.
      If a config file is explicitly specified with a module option then the
      files in the above directory are not parsed.
    </para>
    <para condition="with_vendordir">
      By default limits are taken from the <filename>/etc/security/limits.conf</filename>
      config file or, if that one is not present, the file
      <filename>%vendordir%/security/limits.conf</filename>.
      Then individual <filename>*.conf</filename> files from the
      <filename>/etc/security/limits.d/</filename> and
      <filename>%vendordir%/security/limits.d</filename> directories are read.
      If <filename>/etc/security/limits.d/@filename@.conf</filename> exists, then
      <filename>%vendordir%/security/limits.d/@filename@.conf</filename> will not be used.
      All <filename>limits.d/*.conf</filename> files are sorted by their
      <filename>@filename@.conf</filename> in lexicographic order regardless of which
      of the directories they reside in.
      The effect of the individual files is the same as if all the files were
      concatenated together in the order of parsing.
      If a config file is explicitly specified with the <option>config</option>
      option the files in the above directories are not parsed.
    </para>
    <para>
      The module must not be called by a multithreaded application.
    </para>
    <para>
      If Linux PAM is compiled with audit support the module will report
      when it denies access based on limit of maximum number of concurrent
      login sessions.
    </para>
  </refsect1>

  <refsect1 xml:id="pam_limits-options">
    <title>OPTIONS</title>
    <variablelist>
      <varlistentry>
        <term>
          conf=/path/to/limits.conf
        </term>
        <listitem>
          <para>
            Indicate an alternative limits.conf style configuration file to
            override the default.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          debug
        </term>
        <listitem>
          <para>
            Print debug information.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          set_all
        </term>
        <listitem>
          <para>
            Set the limits for which no value is specified in the
            configuration file to the one from the process with the
            PID 1. Please note that if the init process is systemd
            these limits will not be the kernel default limits and
            this option should not be used.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          utmp_early
        </term>
        <listitem>
          <para>
            Some broken applications actually allocate a utmp entry for
            the user before the user is admitted to the system. If some
            of the services you are configuring PAM for do this, you can
            selectively use this module argument to compensate for this
            behavior and at the same time maintain system-wide consistency
            with a single limits.conf file.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>
          noaudit
        </term>
        <listitem>
          <para>
            Do not report exceeded maximum logins count to the audit subsystem.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 xml:id="pam_limits-types">
    <title>MODULE TYPES PROVIDED</title>
    <para>
      Only the <option>session</option> module type is provided.
    </para>
  </refsect1>

  <refsect1 xml:id="pam_limits-return_values">
    <title>RETURN VALUES</title>
    <variablelist>
      <varlistentry>
        <term>PAM_ABORT</term>
        <listitem>
           <para>
             Cannot get current limits.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_IGNORE</term>
        <listitem>
           <para>
             No limits found for this user.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_PERM_DENIED</term>
        <listitem>
          <para>
            New limits could not be set.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_SERVICE_ERR</term>
        <listitem>
           <para>
             Cannot read config file.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_SESSION_ERR</term>
        <listitem>
           <para>
             Error recovering account name.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_SUCCESS</term>
        <listitem>
           <para>
             Limits were changed.
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term>PAM_USER_UNKNOWN</term>
        <listitem>
           <para>
             The user is not known to the system.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 xml:id="pam_limits-files">
    <title>FILES</title>
    <variablelist>
      <varlistentry>
        <term>/etc/security/limits.conf</term>
        <listitem>
          <para>Default configuration file</para>
        </listitem>
      </varlistentry>
      <varlistentry condition="with_vendordir">
        <term>%vendordir%/security/limits.conf</term>
        <listitem>
          <para>Default configuration file if
	  <filename>/etc/security/limits.conf</filename> does not exist.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1 xml:id="pam_limits-examples">
    <title>EXAMPLES</title>
    <para>
      For the services you need resources limits (login for example) put a
      the following line in <filename>/etc/pam.d/login</filename> as the last
      line for that service (usually after the pam_unix session line):
    </para>
    <programlisting>
#%PAM-1.0
#
# Resource limits imposed on login sessions via pam_limits
#
session  required  pam_limits.so
    </programlisting>
    <para>
      Replace "login" for each service you are using this module.
    </para>
  </refsect1>

  <refsect1 xml:id="pam_limits-see_also">
    <title>SEE ALSO</title>
    <para>
      <citerefentry>
        <refentrytitle>limits.conf</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>pam</refentrytitle><manvolnum>7</manvolnum>
      </citerefentry>.
    </para>
  </refsect1>

  <refsect1 xml:id="pam_limits-authors">
    <title>AUTHORS</title>
    <para>
      pam_limits was initially written by Cristian Gafton &lt;gafton@redhat.com&gt;
    </para>
  </refsect1>
</refentry>