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<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
<refentry id='pam_group'>
<refmeta>
<refentrytitle>pam_group</refentrytitle>
<manvolnum>8</manvolnum>
<refmiscinfo class='setdesc'>Linux-PAM Manual</refmiscinfo>
</refmeta>
<refnamediv id='pam_group-name'>
<refname>pam_group</refname>
<refpurpose>
PAM module for group access
</refpurpose>
</refnamediv>
<!-- body begins here -->
<refsynopsisdiv>
<cmdsynopsis id="pam_group-cmdsynopsis">
<command>pam_group.so</command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1 id="pam_group-description">
<title>DESCRIPTION</title>
<para>
The pam_group PAM module does not authenticate the user, but instead
it grants group memberships (in the credential setting phase of the
authentication module) to the user. Such memberships are based on the
service they are applying for.
</para>
<para>
By default rules for group memberships are taken from config file
<filename>/etc/security/group.conf</filename>.
</para>
<para>
This module's usefulness relies on the file-systems
accessible to the user. The point being that once granted the
membership of a group, the user may attempt to create a
<function>setgid</function> binary with a restricted group ownership.
Later, when the user is not given membership to this group, they can
recover group membership with the precompiled binary. The reason that
the file-systems that the user has access to are so significant, is the
fact that when a system is mounted <emphasis>nosuid</emphasis> the user
is unable to create or execute such a binary file. For this module to
provide any level of security, all file-systems that the user has write
access to should be mounted <emphasis>nosuid</emphasis>.
</para>
<para>
The pam_group module functions in parallel with the
<filename>/etc/group</filename> file. If the user is granted any groups
based on the behavior of this module, they are granted
<emphasis>in addition</emphasis> to those entries
<filename>/etc/group</filename> (or equivalent).
</para>
</refsect1>
<refsect1 id="pam_group-options">
<title>OPTIONS</title>
<para>This module does not recognise any options.</para>
</refsect1>
<refsect1 id="pam_group-types">
<title>MODULE TYPES PROVIDED</title>
<para>
Only the <option>auth</option> module type is provided.
</para>
</refsect1>
<refsect1 id="pam_group-return_values">
<title>RETURN VALUES</title>
<variablelist>
<varlistentry>
<term>PAM_SUCCESS</term>
<listitem>
<para>
group membership was granted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>PAM_ABORT</term>
<listitem>
<para>
Not all relevant data could be gotten.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>PAM_BUF_ERR</term>
<listitem>
<para>
Memory buffer error.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>PAM_CRED_ERR</term>
<listitem>
<para>
Group membership was not granted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>PAM_IGNORE</term>
<listitem>
<para>
<function>pam_sm_authenticate</function> was called which does nothing.
</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 id="pam_group-files">
<title>FILES</title>
<variablelist>
<varlistentry>
<term><filename>/etc/security/group.conf</filename></term>
<listitem>
<para>Default configuration file</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="pam_group-see_also">
<title>SEE ALSO</title>
<para>
<citerefentry>
<refentrytitle>group.conf</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>.
</para>
</refsect1>
<refsect1 id="pam_group-authors">
<title>AUTHORS</title>
<para>
pam_group was written by Andrew G. Morgan <morgan@kernel.org>.
</para>
</refsect1>
</refentry>
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