PAM_SM_AUTHENTICATE(3PAM) PAM Library Functions PAM_SM_AUTHENTICATE(3PAM)
NAME
pam_sm_authenticate - service provider implementation for
pam_authenticate
SYNOPSIS
cc [
flag... ]
file...
-lpam [
library... ]
#include <security/pam_appl.h>
#include <security/pam_modules.h>
int pam_sm_authenticate(
pam_handle_t *pamh,
int flags,
int argc,
const char **argv);
DESCRIPTION
In response to a call to
pam_authenticate(3PAM), the
PAM framework
calls
pam_sm_authenticate() from the modules listed in the
pam.conf(5) file. The authentication provider supplies the back-end
functionality for this interface function.
The
pam_sm_authenticate() function is called to verify the identity
of the current user. The user is usually required to enter a password
or similar authentication token depending upon the authentication
scheme configured within the system. The user in question is
specified by a prior call to
pam_start(), and is referenced by the
authentication handle
pamh.
If the user is unknown to the authentication service, the service
module should mask this error and continue to prompt the user for a
password. It should then return the error,
PAM_USER_UNKNOWN.
The following flags may be passed in to
pam_sm_authenticate():
PAM_SILENT The authentication service should not
generate any messages.
PAM_DISALLOW_NULL_AUTHTOK The authentication service should return
PAM_AUTH_ERR The user has a null authentication
token.
The
argc argument represents the number of module options passed in
from the configuration file
pam.conf(5).
argv specifies the module
options, which are interpreted and processed by the authentication
service. Please refer to the specific module man pages for the
various available
options. If any unknown option is passed in, the
module should log the error and ignore the option.
Before returning,
pam_sm_authenticate() should call
pam_get_item() and retrieve
PAM_AUTHTOK. If it has not been set before and the value
is
NULL,
pam_sm_authenticate() should set it to the password entered
by the user using
pam_set_item().
An authentication module may save the authentication status (success
or reason for failure) as state in the authentication handle using
pam_set_data(3PAM). This information is intended for use by
pam_setcred().
RETURN VALUES
Upon successful completion,
PAM_SUCCESS must be returned. In
addition, the following values may be returned:
PAM_MAXTRIES Maximum number of authentication attempts
exceeded.
PAM_AUTH_ERR Authentication failure.
PAM_CRED_INSUFFICIENT Cannot access authentication data due to
insufficient credentials.
PAM_AUTHINFO_UNAVAIL Underlying authentication service can not
retrieve authentication information.
PAM_USER_UNKNOWN User not known to underlying authentication
module.
PAM_IGNORE Ignore underlying authentication module
regardless of whether the control flag is
required,
optional, or
sufficient.
ATTRIBUTES
See
attributes(7) for description of the following attributes:
+--------------------+-------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------------+
|Interface Stability | Stable |
+--------------------+-------------------------+
|MT-Level | MT-Safe with exceptions |
+--------------------+-------------------------+
SEE ALSO
libpam(3LIB),
pam(3PAM),
pam_authenticate(3PAM),
pam_get_item(3PAM),
pam_set_data(3PAM),
pam_set_item(3PAM),
pam_setcred(3PAM),
pam_start(3PAM),
pam.conf(5),
attributes(7)NOTES
Modules should not retry the authentication in the event of a
failure. Applications handle authentication retries and maintain the
retry count. To limit the number of retries, the module can return a
PAM_MAXTRIES error.
The interfaces in
libpam(3LIB) are MT-Safe only if each thread within
the multithreaded application uses its own
PAM handle.
If the
PAM_REPOSITORY item_type is set and a service module does not
recognize the type, the service module does not process any
information, and returns
PAM_IGNORE. If the
PAM_REPOSITORY item_type is not set, a service module performs its default action.
August 19, 2023 PAM_SM_AUTHENTICATE(3PAM)
