'\" t
.\"     Title: pam_group
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets v1.79.2 <http://docbook.sf.net/>
.\"      Date: 08/28/2024
.\"    Manual: Linux-PAM Manual
.\"    Source: Linux-PAM
.\"  Language: English
.\"
.TH "PAM_GROUP" "8" "08/28/2024" "Linux\-PAM" "Linux\-PAM Manual"
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.SH "NAME"
pam_group \- PAM module for group access
.SH "SYNOPSIS"
.HP \w'\fBpam_group\&.so\fR\ 'u
\fBpam_group\&.so\fR
.SH "DESCRIPTION"
.PP
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\&.
.PP
By default rules for group memberships are taken from config file
/etc/security/group\&.conf\&.
.PP
This module\*(Aqs 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
\fBsetgid\fR
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
\fInosuid\fR
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
\fInosuid\fR\&.
.PP
The pam_group module functions in parallel with the
/etc/group
file\&. If the user is granted any groups based on the behavior of this module, they are granted
\fIin addition\fR
to those entries
/etc/group
(or equivalent)\&.
.SH "OPTIONS"
.PP
This module does not recognise any options\&.
.SH "MODULE TYPES PROVIDED"
.PP
Only the
\fBauth\fR
module type is provided\&.
.SH "RETURN VALUES"
.PP
PAM_SUCCESS
.RS 4
group membership was granted\&.
.RE
.PP
PAM_ABORT
.RS 4
Not all relevant data could be gotten\&.
.RE
.PP
PAM_BUF_ERR
.RS 4
Memory buffer error\&.
.RE
.PP
PAM_CRED_ERR
.RS 4
Group membership was not granted\&.
.RE
.PP
PAM_IGNORE
.RS 4
\fBpam_sm_authenticate\fR
was called which does nothing\&.
.RE
.PP
PAM_USER_UNKNOWN
.RS 4
The user is not known to the system\&.
.RE
.SH "FILES"
.PP
/etc/security/group\&.conf
.RS 4
Default configuration file
.RE
.SH "SEE ALSO"
.PP
\fBgroup.conf\fR(5),
\fBpam.d\fR(5),
\fBpam\fR(8)\&.
.SH "AUTHORS"
.PP
pam_group was written by Andrew G\&. Morgan <morgan@kernel\&.org>\&.