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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="pam_group">
<refmeta>
<refentrytitle>pam_group</refentrytitle>
<manvolnum>8</manvolnum>
<refmiscinfo class="source">Linux-PAM</refmiscinfo>
<refmiscinfo class="manual">Linux-PAM Manual</refmiscinfo>
</refmeta>
<refnamediv xml:id="pam_group-name">
<refname>pam_group</refname>
<refpurpose>
PAM module for group access
</refpurpose>
</refnamediv>
<!-- body begins here -->
<refsynopsisdiv>
<cmdsynopsis xml:id="pam_group-cmdsynopsis" sepchar=" ">
<command>pam_group.so</command>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1 xml: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 condition="with_vendordir">
If <filename>/etc/security/group.conf</filename> does not exist,
<filename>%vendordir%/security/group.conf</filename> is used.
</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 xml:id="pam_group-options">
<title>OPTIONS</title>
<para>This module does not recognise any options.</para>
</refsect1>
<refsect1 xml:id="pam_group-types">
<title>MODULE TYPES PROVIDED</title>
<para>
Only the <option>auth</option> module type is provided.
</para>
</refsect1>
<refsect1 xml: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 xml:id="pam_group-files">
<title>FILES</title>
<variablelist>
<varlistentry>
<term>/etc/security/group.conf</term>
<listitem>
<para>Default configuration file</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml: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 xml: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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