pam_unix(5)

NAME

pam_unix — authentication, account, session, and password management PAM modules for UNIX

SYNOPSIS

/usr/lib/security/$ISA/libpam_unix.so.1

DESCRIPTION

The UNIX service module for PAM, /usr/lib/security/$ISA/libpam_unix.so.1, provides functionality for all four PAM modules: authentication, account management, session management and password management.

The libpam_unix.so.1 module is a shared object that can be dynamically loaded to provide the necessary functionality upon demand.

For an interpretation of the module path, please refer to the related information in pam.conf(4).

Unix Authentication Module

The UNIX authentication component provides functions to verify the identity of a user, (pam_sm_authenticate()) and to set user specific credentials (pam_sm_setcred()).

pam_sm_authenticate() compares the user entered password (or password retrieved from the user's smart card) with the password from UNIX password database, including the protected password database for trusted systems. If the passwords match, the user is authenticated. If the user also has secure RPC credentials and the secure RPC password is the same as the UNIX password, then the secure RPC credentials are also obtained.

The following options may be passed to the UNIX service module:

debug: syslog(3C) debugging information at LOG_DEBUG level.
nowarn: Turn off warning messages.
use_first_pass: It compares the password in the password database with the user's initial password (entered when the user authenticated to the first authentication module in the stack). If the passwords do not match, or if no password has been entered, quit and do not prompt the user for a password. This option should only be used if the authentication service is designated as optional in the pam.conf configuration file.
try_first_pass: It compares the password in the password database with the user's initial password (entered when the user authenticated to the first authentication module in the stack). If the passwords do not match, or if no password has been entered, prompt the user for a password.
use_psd: psd stands for personal security device, for the current implementation there is only one security device: the smart card. It compares the password in the password database with the password stored on the user's smart card. With this option the PAM Framework prompt "Enter PIN:" is used instead of the password prompt. This option is only supported with the authentication or password module types (auth, password) services in the pam.conf or in the pam_user.conf configuration files.

When prompting for the current password, the UNIX authentication module will use the prompt, "Password:" unless one of the following scenarios occur:

1.: The option try_first_pass is specified and the password entered for the first module in the stack fails for the UNIX module.
2.: The option try_first_pass is not specified, and the earlier authentication modules listed in the pam.conf file have prompted the user for the password.
3.: The option use_psd is specified. In this case, the UNIX authentication module will use the prompt "Enter PIN:".

In cases 1 and 2, the UNIX authentication module will use the prompt "System Password:".

The pam_sm_setcred() function sets user specific credentials. If the user had secure RPC credentials, but the secure RPC password was not the same as the UNIX password, then a warning message is printed. If the user wants to get secure RPC credentials, then keylogin(1) needs to be run.

Unix Account Management Module

The UNIX account management component provides a function to perform account management (pam_sm_acct_mgmt()). The function retrieves the user's password entry from the UNIX password database and verifies that the user's account and password have not expired. For trusted systems, this module also validates the allowed access time and access terminal based upon the security configuration. The following options may be passed in to the UNIX service module:

debug: syslog(3C) debugging information at LOG_DEBUG level.
nowarn: Turn off warning messages.

Unix Session Management Module

The UNIX session management component provides functions to initiate (pam_sm_open_session()) and terminate (pam_sm_close_session()) UNIX sessions. For UNIX, pam_open_session() updates the last successful or unsuccessful login time in the protected password database for trusted mode. The account management module reads the information to display the previous time the user logged in.

The following options may be passed in to the UNIX service module:

debug: syslog(3C) debugging information at LOG_DEBUG level.
nowarn: Turn off warning messages.

pam_close_session is a NULL function.

Unix Password Management Module

The UNIX password management component provides a function to change passwords (pam_sm_chauthtok()) in the UNIX password database. This module must be required in pam.conf. It can not be optional or sufficient. The following options may be passed in to the UNIX service module:

debug: syslog(3C) debugging information at LOG_DEBUG level.
nowarn: Turn off warning messages.
use_first_pass: It compares the password in the password database with the user's old password (entered to the first password module in the stack). If the passwords do not match, or if no password has been entered, quit and do not prompt the user for the old password. It also attempts to use the new password (entered to the first password module in the stack) as the new password for this module. If the new password fails, quit and do not prompt the user for a new password.
try_first_pass: It compares the password in the password database with the user's old password (entered to the first password module in the stack). If the passwords do not match, or if no password has been entered, prompt the user for the old password. It also attempts to use the new password (entered to the first password module in the stack) as the new password for this module. If the new password fails, prompt the user for a new password.
use_psd: It prompts the user for the PIN (with the PIN, the PAM Framework can retrieve a password from the smart card) and the old password is retrieved from the smart card. It compares the password in the password database with the user's old password. If the passwords match, it prompts the user for a new password.

If the user's password has expired, the UNIX account module saves this information in the authentication handle using pam_set_data(). The UNIX password module retrieves this information from the authentication handle using pam_get_data() to determine whether or not to force the user to update their password.

APPLICATION USAGE

On trusted systems, the pam_sm_*() interfaces implemented in the UNIX service module, libpam_unix, are not thread-safe. Otherwise, they are thread-safe. A cancellation point may occur while a thread is executing any of these interfaces. They are not cancel-safe, async-cancel-safe, nor async-signal-safe.

WARNINGS

HP-UX 11i Version 3 is the last release to support trusted systems functionality.