PAM(3)                   BSD Library Functions Manual                   PAM(3)

NAME
     pam_acct_mgmt, pam_authenticate, pam_chauthtok, pam_close_session,
     pam_end, pam_get_data, pam_get_item, pam_get_user, pam_getenv,
     pam_getenvlist, pam_open_session, pam_putenv, pam_set_data, pam_set_item,
     pam_setcred, pam_start, pam_strerror -- Pluggable Authentication Modules
     Library

LIBRARY
     Pluggable Authentication Module Library (libpam, -lpam)

SYNOPSIS
     #include <security/pam_appl.h>

     int
     pam_acct_mgmt(pam_handle_t *pamh, int flags);

     int
     pam_authenticate(pam_handle_t *pamh, int flags);

     int
     pam_chauthtok(pam_handle_t *pamh, int flags);

     int
     pam_close_session(pam_handle_t *pamh, int flags);

     int
     pam_end(pam_handle_t *pamh, int status);

     int
     pam_get_data(const pam_handle_t *pamh, const char *module_data_name,
         const void **data);

     int
     pam_get_item(const pam_handle_t *pamh, int item_type, const void **item);

     int
     pam_get_user(pam_handle_t *pamh, const char **user, const char *prompt);

     const char *
     pam_getenv(pam_handle_t *pamh, const char *name);

     char **
     pam_getenvlist(pam_handle_t *pamh);

     int
     pam_open_session(pam_handle_t *pamh, int flags);

     int
     pam_putenv(pam_handle_t *pamh, const char *namevalue);

     int
     pam_set_data(pam_handle_t *pamh, const char *module_data_name,
         void *data,
         void (*cleanup)(pam_handle_t *pamh, void *data, int pam_end_status));

     int
     pam_set_item(pam_handle_t *pamh, int item_type, const void *item);

     int
     pam_setcred(pam_handle_t *pamh, int flags);

     int
     pam_start(const char *service, const char *user,
         const struct pam_conv *pam_conv, pam_handle_t **pamh);

     const char *
     pam_strerror(const pam_handle_t *pamh, int error_number);

DESCRIPTION
     The Pluggable Authentication Modules (PAM) library abstracts a number of
     common authentication-related operations and provides a framework for
     dynamically loaded modules that implement these operations in various
     ways.

   Terminology
     In PAM parlance, the application that uses PAM to authenticate a user is
     the server, and is identified for configuration purposes by a service
     name, which is often (but not necessarily) the program name.

     The user requesting authentication is called the applicant, while the
     user (usually, root) charged with verifying his identity and granting him
     the requested credentials is called the arbitrator.

     The sequence of operations the server goes through to authenticate a user
     and perform whatever task he requested is a PAM transaction; the context
     within which the server performs the requested task is called a session.

     The functionality embodied by PAM is divided into six primitives grouped
     into four facilities: authentication, account management, session manage-
     ment and password management.

   Conversation
     The PAM library expects the application to provide a conversation call-
     back which it can use to communicate with the user.  Some modules may use
     specialized conversation functions to communicate with special hardware
     such as cryptographic dongles or biometric devices.  See pam_conv(3) for
     details.

   Initialization and Cleanup
     The pam_start() function initializes the PAM library and returns a handle
     which must be provided in all subsequent function calls.  The transaction
     state is contained entirely within the structure identified by this han-
     dle, so it is possible to conduct multiple transactions in parallel.

     The pam_end() function releases all resources associated with the speci-
     fied context, and can be called at any time to terminate a PAM transac-
     tion.

   Storage
     The pam_set_item() and pam_get_item() functions set and retrieve a number
     of predefined items, including the service name, the names of the
     requesting and target users, the conversation function, and prompts.

     The pam_set_data() and pam_get_data() functions manage named chunks of
     free-form data, generally used by modules to store state from one invoca-
     tion to another.

   Authentication
     There are two authentication primitives: pam_authenticate() and
     pam_setcred().  The former authenticates the user, while the latter man-
     ages his credentials.

   Account Management
     The pam_acct_mgmt() function enforces policies such as password expiry,
     account expiry, time-of-day restrictions, and so forth.

   Session Management
     The pam_open_session() and pam_close_session() functions handle session
     setup and teardown.

   Password Management
     The pam_chauthtok() function allows the server to change the user's pass-
     word, either at the user's request or because the password has expired.

   Miscellaneous
     The pam_putenv(), pam_getenv() and pam_getenvlist() functions manage a
     private environment list in which modules can set environment variables
     they want the server to export during the session.

     The pam_strerror() function returns a pointer to a string describing the
     specified PAM error code.

RETURN VALUES
     The following return codes are defined by <security/pam_constants.h>:

     [PAM_ABORT]         General failure.

     [PAM_ACCT_EXPIRED]  User account has expired.

     [PAM_AUTHINFO_UNAVAIL]
                         Authentication information is unavailable.

     [PAM_AUTHTOK_DISABLE_AGING]
                         Authentication token aging disabled.

     [PAM_AUTHTOK_ERR]   Authentication token failure.

     [PAM_AUTHTOK_EXPIRED]
                         Password has expired.

     [PAM_AUTHTOK_LOCK_BUSY]
                         Authentication token lock busy.

     [PAM_AUTHTOK_RECOVERY_ERR]
                         Failed to recover old authentication token.

     [PAM_AUTH_ERR]      Authentication error.

     [PAM_BUF_ERR]       Memory buffer error.

     [PAM_CONV_ERR]      Conversation failure.

     [PAM_CRED_ERR]      Failed to set user credentials.

     [PAM_CRED_EXPIRED]  User credentials have expired.

     [PAM_CRED_INSUFFICIENT]
                         Insufficient credentials.

     [PAM_CRED_UNAVAIL]  Failed to retrieve user credentials.

     [PAM_DOMAIN_UNKNOWN]
                         Unknown authentication domain.

     [PAM_IGNORE]        Ignore this module.

     [PAM_MAXTRIES]      Maximum number of tries exceeded.

     [PAM_MODULE_UNKNOWN]
                         Unknown module type.

     [PAM_NEW_AUTHTOK_REQD]
                         New authentication token required.

     [PAM_NO_MODULE_DATA]
                         Module data not found.

     [PAM_OPEN_ERR]      Failed to load module.

     [PAM_PERM_DENIED]   Permission denied.

     [PAM_SERVICE_ERR]   Error in service module.

     [PAM_SESSION_ERR]   Session failure.

     [PAM_SUCCESS]       Success.

     [PAM_SYMBOL_ERR]    Invalid symbol.

     [PAM_SYSTEM_ERR]    System error.

     [PAM_TRY_AGAIN]     Try again.

     [PAM_USER_UNKNOWN]  Unknown user.

SEE ALSO
     openpam(3), pam_acct_mgmt(3), pam_authenticate(3), pam_chauthtok(3),
     pam_close_session(3), pam_conv(3), pam_end(3), pam_get_data(3),
     pam_getenv(3), pam_getenvlist(3), pam_get_item(3), pam_get_user(3),
     pam_open_session(3), pam_putenv(3), pam_setcred(3), pam_set_data(3),
     pam_set_item(3), pam_start(3), pam_strerror(3)

STANDARDS
     X/Open Single Sign-On Service (XSSO) - Pluggable Authentication Modules,
     June 1997.

AUTHORS
     The OpenPAM library and this manual page were developed for the FreeBSD
     Project by ThinkSec AS and Network Associates Laboratories, the Security
     Research Division of Network Associates, Inc. under DARPA/SPAWAR contract
     N66001-01-C-8035 (``CBOSS''), as part of the DARPA CHATS research pro-
     gram.

BSD                            December 21, 2007                           BSD