'\" t
.\"     Title: pam_sm_authenticate
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 09/03/2021
.\"    Manual: Linux-PAM Manual
.\"    Source: Linux-PAM Manual
.\"  Language: English
.\"
.TH "PAM_SM_AUTHENTICATE" "3" "09/03/2021" "Linux-PAM Manual" "Linux-PAM Manual"
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.SH "NAME"
pam_sm_authenticate \- PAM service function for user authentication
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <security/pam_modules\&.h>
.fi
.ft
.HP \w'int\ pam_sm_authenticate('u
.BI "int pam_sm_authenticate(pam_handle_t\ *" "pamh" ", int\ " "flags" ", int\ " "argc" ", const\ char\ **" "argv" ");"
.SH "DESCRIPTION"
.PP
The
\fBpam_sm_authenticate\fR
function is the service module\*(Aqs implementation of the
\fBpam_authenticate\fR(3)
interface\&.
.PP
This function performs the task of authenticating the user\&.
.PP
Valid flags, which may be logically OR\*(Aqd with
\fIPAM_SILENT\fR, are:
.PP
PAM_SILENT
.RS 4
Do not emit any messages\&.
.RE
.PP
PAM_DISALLOW_NULL_AUTHTOK
.RS 4
Return
\fBPAM_AUTH_ERR\fR
if the database of authentication tokens for this authentication mechanism has a
\fINULL\fR
entry for the user\&. Without this flag, such a
\fINULL\fR
token will lead to a success without the user being prompted\&.
.RE
.SH "RETURN VALUES"
.PP
PAM_AUTH_ERR
.RS 4
Authentication failure\&.
.RE
.PP
PAM_CRED_INSUFFICIENT
.RS 4
For some reason the application does not have sufficient credentials to authenticate the user\&.
.RE
.PP
PAM_AUTHINFO_UNAVAIL
.RS 4
The modules were not able to access the authentication information\&. This might be due to a network or hardware failure etc\&.
.RE
.PP
PAM_SUCCESS
.RS 4
The authentication token was successfully updated\&.
.RE
.PP
PAM_USER_UNKNOWN
.RS 4
The supplied username is not known to the authentication service\&.
.RE
.PP
PAM_MAXTRIES
.RS 4
One or more of the authentication modules has reached its limit of tries authenticating the user\&. Do not try again\&.
.RE
.SH "SEE ALSO"
.PP
\fBpam\fR(3),
\fBpam_authenticate\fR(3),
\fBpam_sm_setcred\fR(3),
\fBpam_strerror\fR(3),
\fBPAM\fR(8)