pam_sm_chauthtok - PAM service function for authentication token
PAM_EXTERN int pam_sm_chauthtok(pam_handle_t *pamh, int flags,
int argc, const char **argv);
The pam_sm_chauthtok function is the service module's implementation of
the pam_chauthtok(3) interface.
This function is used to (re-)set the authentication token of the user.
Valid flags, which may be logically OR'd with PAM_SILENT, are:
Do not emit any messages.
This argument indicates to the module that the users authentication
token (password) should only be changed if it has expired. This
flag is optional and must be combined with one of the following two
flags. Note, however, the following two options are mutually
This indicates that the modules are being probed as to their ready
status for altering the user's authentication token. If the module
requires access to another system over some network it should
attempt to verify it can connect to this system on receiving this
flag. If a module cannot establish it is ready to update the user's
authentication token it should return PAM_TRY_AGAIN, this
information will be passed back to the application.
If the control value sufficient is used in the password stack, the
PAM_PRELIM_CHECK section of the modules following that control
value is not always executed.
This informs the module that this is the call it should change the
authorization tokens. If the flag is logically OR'd with
PAM_CHANGE_EXPIRED_AUTHTOK, the token is only changed if it has
The PAM library calls this function twice in succession. The first time
with PAM_PRELIM_CHECK and then, if the module does not return
PAM_TRY_AGAIN, subsequently with PAM_UPDATE_AUTHTOK. It is only on the
second call that the authorization token is (possibly) changed.
The module was unable to obtain the new authentication token.
The module was unable to obtain the old authentication token.
Cannot change the authentication token since it is currently
Authentication token aging has been disabled.
Preliminary check was unsuccessful. Signals an immediate return to
the application is desired.
The authentication token was successfully updated.
User unknown to password service.
pam(3), pam_chauthtok(3), pam_sm_chauthtok(3), pam_strerror(3), PAM(8)