Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.

PAM(3)                     Library Functions Manual                     PAM(3)

     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

     Pluggable Authentication Module Library (libpam, -lpam)

     #include <security/pam_appl.h>

     pam_acct_mgmt(pam_handle_t *pamh, int flags);

     pam_authenticate(pam_handle_t *pamh, int flags);

     pam_chauthtok(pam_handle_t *pamh, int flags);

     pam_close_session(pam_handle_t *pamh, int flags);

     pam_end(pam_handle_t *pamh, int status);

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

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

     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);

     pam_open_session(pam_handle_t *pamh, int flags);

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

     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));

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

     pam_setcred(pam_handle_t *pamh, int flags);

     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);

     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

     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
     management and password management.

     The PAM library expects the application to provide a conversation
     callback 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
     handle, so it is possible to conduct multiple transactions in parallel.

     The pam_end() function releases all resources associated with the
     specified context, and can be called at any time to terminate a PAM

     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
     invocation to another.

     There are two authentication primitives: pam_authenticate() and
     pam_setcred().  The former authenticates the user, while the latter
     manages 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
     password, either at the user's request or because the password has

     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.

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

     [PAM_ABORT]         General failure.

     [PAM_ACCT_EXPIRED]  User account has expired.

                         Authentication information is unavailable.

                         Authentication token aging disabled.

     [PAM_AUTHTOK_ERR]   Authentication token failure.

                         Password has expired.

                         Authentication token lock busy.

                         Failed to recover old authentication token.

     [PAM_AUTH_ERR]      Authentication error.

     [PAM_BAD_CONSTANT]  Bad constant.

     [PAM_BAD_FEATURE]   Unrecognized or restricted feature.

     [PAM_BAD_HANDLE]    Invalid PAM handle.

     [PAM_BAD_ITEM]      Unrecognized or restricted item.

     [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.

                         Insufficient credentials.

     [PAM_CRED_UNAVAIL]  Failed to retrieve user credentials.

                         Unknown authentication domain.

     [PAM_IGNORE]        Ignore this module.

     [PAM_MAXTRIES]      Maximum number of tries exceeded.

                         Unknown module type.

                         New authentication token required.

                         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.

     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)

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

     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 program.

     The OpenPAM library is maintained by Dag-Erling Sm/orgrav <des@des.no>.

NetBSD 10.99                     June 27, 2023                    NetBSD 10.99