PAM_WHEEL

Section: Linux\-PAM Manual (8)
Updated: 11/25/2020
Page Index

NAME

pam_wheel - Only permit root access to members of group wheel

SYNOPSIS

pam_wheel.so [debug] [deny] [group=name] [root_only] [trust] [use_uid]

DESCRIPTION

The pam_wheel PAM module is used to enforce the so-called wheel group. By default it permits access to the target user if the applicant user is a member of the wheel group. If no group with this name exist, the module is using the group with the group-ID 0.

OPTIONS

debug

: Print debug information.

deny

: Reverse the sense of the auth operation: if the user is trying to get UID 0 access and is a member of the wheel group (or the group of the group option), deny access. Conversely, if the user is not in the group, return PAM_IGNORE (unless trust was also specified, in which case we return PAM_SUCCESS).

group=name

: Instead of checking the wheel or GID 0 groups, use the name group to perform the authentication.

root_only

: The check for wheel membership is done only when the target user UID is 0.

trust

: The pam_wheel module will return PAM_SUCCESS instead of PAM_IGNORE if the user is a member of the wheel group (thus with a little play stacking the modules the wheel members may be able to su to root without being prompted for a passwd).

use_uid

: The check will be done against the real uid of the calling process, instead of trying to obtain the user from the login session associated with the terminal in use.

MODULE TYPES PROVIDED

The auth and account module types are provided.

RETURN VALUES

PAM_AUTH_ERR

: Authentication failure.

PAM_BUF_ERR

: Memory buffer error.

PAM_IGNORE

: The return value should be ignored by PAM dispatch.

PAM_PERM_DENY

: Permission denied.

PAM_SERVICE_ERR

: Cannot determine the user name.

PAM_SUCCESS

: Success.

PAM_USER_UNKNOWN

: User not known.

EXAMPLES

The root account gains access by default (rootok), only wheel members can become root (wheel) but Unix authenticate non-root applicants.

su      auth     sufficient     pam_rootok.so
su      auth     required       pam_wheel.so
su      auth     required       pam_unix.so

AUTHOR

pam_wheel was written by Cristian Gafton <gafton@redhat.com>.