pam_set_item(3) — Linux manual page


PAM_SET_ITEM(3)             Linux-PAM Manual             PAM_SET_ITEM(3)

NAME         top

       pam_set_item - set and update PAM information

SYNOPSIS         top

       #include <security/pam_modules.h>

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

DESCRIPTION         top

       The pam_set_item function allows applications and PAM service
       modules to access and to update PAM information of item_type. For
       this a copy of the object pointed to by the item argument is
       created. The following item_types are supported:

           The service name (which identifies that PAM stack that the
           PAM functions will use to authenticate the program).

           The username of the entity under whose identity service will
           be given. That is, following authentication, PAM_USER
           identifies the local entity that gets to use the service.
           Note, this value can be mapped from something (eg.,
           "anonymous") to something else (eg. "guest119") by any module
           in the PAM stack. As such an application should consult the
           value of PAM_USER after each call to a PAM function.

           The string used when prompting for a user's name. The default
           value for this string is a localized version of "login: ".

           The terminal name: prefixed by /dev/ if it is a device file;
           for graphical, X-based, applications the value for this item
           should be the $DISPLAY variable.

           The requesting user name: local name for a locally requesting
           user or a remote user name for a remote requesting user.

           Generally an application or module will attempt to supply the
           value that is most strongly authenticated (a local account
           before a remote one. The level of trust in this value is
           embodied in the actual authentication stack associated with
           the application, so it is ultimately at the discretion of the
           system administrator.

           PAM_RUSER@PAM_RHOST should always identify the requesting
           user. In some cases, PAM_RUSER may be NULL. In such
           situations, it is unclear who the requesting entity is.

           The requesting hostname (the hostname of the machine from
           which the PAM_RUSER entity is requesting service). That is
           PAM_RUSER@PAM_RHOST does identify the requesting user. In
           some applications, PAM_RHOST may be NULL. In such situations,
           it is unclear where the authentication request is originating

           The authentication token (often a password). This token
           should be ignored by all module functions besides
           pam_sm_authenticate(3) and pam_sm_chauthtok(3). In the former
           function it is used to pass the most recent authentication
           token from one stacked module to another. In the latter
           function the token is used for another purpose. It contains
           the currently active authentication token.

           The old authentication token. This token should be ignored by
           all module functions except pam_sm_chauthtok(3).

           The pam_conv structure. See pam_conv(3).

       The following additional items are specific to Linux-PAM and
       should not be used in portable applications:

           A function pointer to redirect centrally managed failure
           delays. See pam_fail_delay(3).

           The name of the X display. For graphical, X-based
           applications the value for this item should be the $DISPLAY
           variable. This value may be used independently of PAM_TTY for
           passing the name of the display.

           A pointer to a structure containing the X authentication data
           required to make a connection to the display specified by
           PAM_XDISPLAY, if such information is necessary. See

           The default action is for the module to use the following
           prompts when requesting passwords: "New UNIX password: " and
           "Retype UNIX password: ". The example word UNIX can be
           replaced with this item, by default it is empty. This item is
           used by pam_get_authtok(3).

       For all item_types, other than PAM_CONV and PAM_FAIL_DELAY, item
       is a pointer to a <NUL> terminated character string. In the case
       of PAM_CONV, item points to an initialized pam_conv structure. In
       the case of PAM_FAIL_DELAY, item is a function pointer: void
       (*delay_fn)(int retval, unsigned usec_delay, void *appdata_ptr)

       Both, PAM_AUTHTOK and PAM_OLDAUTHTOK, will be reset before
       returning to the application. Which means an application is not
       able to access the authentication tokens.

RETURN VALUES         top

           The application attempted to set an undefined or inaccessible

           Memory buffer error.

           Data was successful updated.

           The pam_handle_t passed as first argument was invalid.

SEE ALSO         top

       pam_get_item(3), pam_strerror(3)

COLOPHON         top

       This page is part of the linux-pam (Pluggable Authentication
       Modules for Linux) project.  Information about the project can be
       found at ⟨⟩.  If you have a bug report
       for this manual page, see ⟨//⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2023-12-18.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

Linux-PAM Manual               12/22/2023                PAM_SET_ITEM(3)

Pages that refer to this page: pam(3)pam_conv(3)pam_end(3)pam_fail_delay(3)pam_get_item(3)pam_get_user(3)pam_start(3)