man pages section 5: Standards, Environments, and Macros

pam_list(5)

Name

pam_list– PAM account management module for UNIX

Synopsis

 pam_list.so.1

Description

The pam_list module implements pam_sm_acct_mgmt(3PAM), which provides functionality to the PAM account management stack. The module provides functions to validate that the user's account is valid on this host based on a list of users and/or netgroups in the given file. The users and netgroups are separated by newline character. Netgroups are specified with character '@' as prefix before name of netgroup in the list. The maximum line lenght is 1023 characters.

The username is the value of PAM_USER. The host is the value of PAM_RHOST or, if PAM_RHOST is not set, the value of the localhost as returned by gethostname(3C) is used.

If neither of the allow, deny, or compat options are specified, the module will look for +/- entries in the local /etc/passwd file. If this style is used, nsswitch.conf(4) must not be configured with compat for the passwd database. If no relevant +/- entry exists for the user, pam_list is not participating in result.

If compat option is specified then the module will look for +/- entries in the local /etc/passwd file. Other entries in this file will be counted as + entries. If no relevant entry exits for the user, pam_list will deny the access.

The following options can be passed to the module:

allow=: The full pathname to a file of allowed users and/or netgroups. Only one of allow= or deny= can be specified.
compat: Activate compat mode.
deny=: The full pathname to a file of denied users and/or netgroups. Only one of deny= or allow= can be specified.
debug: Provide syslog(3C) debugging information at the LOG_AUTH | LOG_DEBUG level.
user: The module should only perform netgroup matches on the username. This is the default option.
nouser: The username should not be used in the netgroup match.
host: Only the host should be used in netgroup matches.
nohost: The hostname should not be used in netgroup matches.
user_host_exact: The user and hostname must be in the same netgroup.

Errors

The following error values are returned:

PAM_SERVICE_ERR: An invalid set of module options was given in the pam.conf(4) for this module, or the user/netgroup file could not be opened.
PAM_BUF_ERR: A memory buffer error occurred.
PAM_IGNORE: The module is ignored, as it is not participating in the result.
PAM_PERM_DENIED: The user is not on the allow list or is on the deny list.
PAM_SUCCESS: The account is valid for use at this time.
PAM_USER_UNKNOWN: No account is present for the user

Examples

Example 1 Using `pam_list` in default mode

/etc/pam.conf modification looks like:

other   account requisite       pam_roles.so.1
other   account required        pam_unix_account.so.1
other   account required        pam_list.so.1

In the case of default mode or compat mode, the important lines in /etc/passwd appear as follows:

+loginname	- user is approved
-loginname	- user is disapproved
+@netgroup	- netgroup members are approved
-@netgroup	- netgroup members are disapproved

Example 2 Using `pam_list` with allow file

/etc/pam.conf modification looks like:

other   account requisite       pam_roles.so.1
other   account required        pam_unix_account.so.1
other   account required        pam_list.so.1 allow=etc/user.allow

/etc/users.allow contains:

root
localloginname
remoteloginname
@netgroup

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Committed
MT-Level	MT-Safe with exceptions

The interfaces in libpam(3LIB) are MT-Safe only if each thread within the multithreaded application uses its own PAM handle.