PAM_GROUP

Section: Linux-PAM Manual (8)
Updated: 06/16/2009
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pam_group - PAM module for group access  

Synopsis

pam_group.so
 

DESCRIPTION

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.

By default rules for group memberships are taken from config file FC/etc/security/group.confF[].

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 setgid 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 nosuid 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 nosuid.

The pam_group module functions in parallel with the FC/etc/groupF[] file. If the user is granted any groups based on the behavior of this module, they are granted in addition to those entries FC/etc/groupF[] (or equivalent).  

OPTIONS

This module does not recognise any options.  

MODULE TYPES PROVIDED

Only the auth module type is provided.  

RETURN VALUES

PAM_SUCCESS

group membership was granted.

PAM_ABORT

Not all relevant data could be gotten.

PAM_BUF_ERR

Memory buffer error.

PAM_CRED_ERR

Group membership was not granted.

PAM_IGNORE

pam_sm_authenticate was called which does nothing.

PAM_USER_UNKNOWN

The user is not known to the system.
 

FILES

FC/etc/security/group.confF[]

Default configuration file
 

SEE ALSO

group.conf(5), pam.d(5), pam(8).  

AUTHORS

pam_group was written by Andrew G. Morgan <morgan@kernel.org>.