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
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/ for device files. In
the past, graphical X-based applications used to store the $DISPLAY
variable here, but with the introduction of PAM_XDISPLAY this usage is
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 from.
The authentication token (often a password). This token
should be ignored by all module functions besides
. 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 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
A pointer to a structure containing the X authentication
data required to make a connection to the display specified by
, 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
replaced with this item, by default it is empty. This item is used by
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
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.