PAM_SET_DATA(3) Linux-PAM Manual PAM_SET_DATA(3)
NAME
pam_set_data - set module internal data
SYNOPSIS
#include <security/pam_modules.h>
int pam_set_data(pam_handle_t *pamh, const char *module_data_name,
void *data,
void (*cleanup)(pam_handle_t *pamh, void *data, int error_status));
DESCRIPTION
The pam_set_data function associates a pointer to an object with the
(hopefully) unique string module_data_name in the PAM context specified
by the pamh argument.
PAM modules may be dynamically loadable objects. In general such files
should not contain static variables. This function and its counterpart
pam_get_data(3), provide a mechanism for a module to associate some data
with the handle pamh. Typically a module will call the pam_set_data
function to register some data under a (hopefully) unique
module_data_name. The data is available for use by other modules too but
not by an application. Since this functions stores only a pointer to the
data, the module should not modify or free the content of it.
The function cleanup() is associated with the data and, if non-NULL, it
is called when this data is over-written or following a call to
pam_end(3).
The error_status argument is used to indicate to the module the sort of
action it is to take in cleaning this data item. As an example, Kerberos
creates a ticket file during the authentication phase, this file might
be associated with a data item. When pam_end(3) is called by the module,
the error_status carries the return value of the pam_authenticate(3) or
other libpam function as appropriate. Based on this value the Kerberos
module may choose to delete the ticket file (authentication failure) or
leave it in place.
The error_status may have been logically OR'd with either of the
following two values:
PAM_DATA_REPLACE
When a data item is being replaced (through a second call to
pam_set_data) this mask is used. Otherwise, the call is assumed to
be from pam_end(3).
PAM_DATA_SILENT
Which indicates that the process would prefer to perform the
cleanup() quietly. That is, discourages logging/messages to the
user. It is generally used to indicate that the current closing of
the library is in a fork(2)ed process, and that the parent will take
care of cleaning up things that exist outside of the current process
space (files etc.).
RETURN VALUES
PAM_BUF_ERR
Memory buffer error.
PAM_SUCCESS
Data was successful stored.
PAM_SYSTEM_ERR
A NULL pointer was submitted as PAM handle or the function was
called by an application.
SEE ALSO
pam_end(3), pam_get_data(3), pam_strerror(3)
Linux-PAM 06/29/2025 PAM_SET_DATA(3)
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