PAM_AUTHENTICATE(3PAM) PAM Library Functions PAM_AUTHENTICATE(3PAM)
NAME
pam_authenticate - perform authentication within the PAM framework
SYNOPSIS
cc [
flag ... ]
file ...
-lpam [
library ... ]
#include <security/pam_appl.h>
int pam_authenticate(
pam_handle_t *pamh,
int flags);
DESCRIPTION
The
pam_authenticate() function is called to authenticate the current
user. The user is usually required to enter a password or similar
authentication token depending upon the authentication service configured
within the system. The user in question should have been specified by a
prior call to
pam_start() or
pam_set_item().
The following flags may be set in the
flags field:
PAM_SILENT Authentication service should not generate
any messages.
PAM_DISALLOW_NULL_AUTHTOK The authentication service should return
PAM_AUTH_ERR if the user has a null
authentication token.
RETURN VALUES
Upon successful completion,
PAM_SUCCESS is returned. In addition to the
error return values described in
pam(3PAM), the following values may be
returned:
PAM_AUTH_ERR Authentication failure.
PAM_CRED_INSUFFICIENT Cannot access authentication data due to
insufficient credentials.
PAM_AUTHINFO_UNAVAIL Underlying authentication service cannot
retrieve authentication information.
PAM_USER_UNKNOWN User not known to the underlying authentication
module.
PAM_MAXTRIES An authentication service has maintained a retry
count which has been reached. No further
retries should be attempted.
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_open_session(3PAM),
pam_set_item(3PAM),
pam_setcred(3PAM),
pam_start(3PAM),
attributes(7)NOTES
In the case of authentication failures due to an incorrect username or
password, it is the responsibility of the application to retry
pam_authenticate() and to maintain the retry count. An authentication
service module may implement an internal retry count and return an error
PAM_MAXTRIES if the module does not want the application to retry.
If the
PAM framework cannot load the authentication module, then it will
return
PAM_ABORT. This indicates a serious failure, and the application
should not attempt to retry the authentication.
For security reasons, the location of authentication failures is hidden
from the user. Thus, if several authentication services are stacked and
a single service fails,
pam_authenticate() requires that the user re-
authenticate each of the services.
A null authentication token in the authentication database will result in
successful authentication unless
PAM_DISALLOW_NULL_AUTHTOK was specified.
In such cases, there will be no prompt to the user to enter an
authentication token.
The interfaces in
libpam are MT-Safe only if each thread within the
multithreaded application uses its own
PAM handle.
January 27, 2005
PAM_AUTHENTICATE(3PAM)