pam_sm_setcred - PAM service function to alter credentials

#include <security/pam_modules.h>

int pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv);

The pam_sm_setcred function is the service module's implementation of the pam_setcred(3) interface.

This function performs the task of altering the credentials of the user with respect to the corresponding authorization scheme. Generally, an authentication module may have access to more information about a user than their authentication token. This function is used to make such information available to the application. It should only be called after the user has been authenticated but before a session has been established.

Valid flags, which may be logically OR'd with PAM_SILENT, are:


Do not emit any messages.


Initialize the credentials for the user.


Delete the credentials associated with the authentication service.


Reinitialize the user credentials.


Extend the lifetime of the user credentials.

The way the auth stack is navigated in order to evaluate the pam_setcred() function call, independent of the pam_sm_setcred() return codes, is exactly the same way that it was navigated when evaluating the pam_authenticate() library call. Typically, if a stack entry was ignored in evaluating pam_authenticate(), it will be ignored when libpam evaluates the pam_setcred() function call. Otherwise, the return codes from each module specific pam_sm_setcred() call are treated as required.


This module cannot retrieve the user's credentials.


The user's credentials have expired.


This module was unable to set the credentials of the user.


The user credential was successfully set.


The user is not known to this authentication module.

These, non-PAM_SUCCESS, return values will typically lead to the credential stack failing. The first such error will dominate in the return value of pam_setcred().

pam(3), pam_authenticate(3), pam_setcred(3), pam_sm_authenticate(3), pam_strerror(3), PAM(8)

04/09/2024 Linux-PAM