PAM_GROUP(8)              (06/08/2020)               PAM_GROUP(8)

     NAME
          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 /etc/security/group.conf.

          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
          /etc/group file. If the user is granted any groups based on
          the behavior of this module, they are granted in addition to
          those entries /etc/group (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.

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     PAM_GROUP(8)              (06/08/2020)               PAM_GROUP(8)

          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
          /etc/security/group.conf
              Default configuration file

     SEE ALSO
          group.conf(5), pam.d(5), pam(7).

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

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