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AuthCookiePAM.pm  view on Meta::CPAN

#===============================================================================
#
# Apache::AuthCookiePAM
#
# An AuthCookie module backed by a PAM.
#
# Copyright (C) 2002 SF Interactive.
#
# Author:  Vandana Awasthi
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
# 
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
# 
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
#===============================================================================

package Apache::AuthCookiePAM;

use strict;
use 5.004;
use vars qw( $VERSION );
( $VERSION ) = '$Revision: 1.0 $' =~ /([\d.]+)/;

use Apache;
use Apache::Table;
use Apache::Constants qw(:common M_GET FORBIDDEN REDIRECT);
use Apache::AuthCookie::Util;
use Apache::Util qw(escape_uri);
use Apache::AuthCookie;
use Authen::PAM;
use vars qw( @ISA );
@ISA = qw( Apache::AuthCookie );

use Apache::File;
use Digest::MD5 qw( md5_hex );
use Date::Calc qw( Today_and_Now Add_Delta_DHMS );
# Also uses Crypt::CBC if you're using encrypted cookies.

#===============================================================================
# F U N C T I O N   D E C L A R A T I O N S
#===============================================================================

sub _log_not_set($$);
sub _dir_config_var($$);
sub _config_vars($);
sub _now_year_month_day_hour_minute_second();
sub _percent_encode($);
sub _percent_decode($);

sub authen_cred($$\@);
sub authen_ses_key($$$);
sub group($$\@);

#===============================================================================
# P A C K A G E   G L O B A L S
#===============================================================================

use vars qw( %CIPHERS );
# Stores Cipher::CBC objects in $CIPHERS{ idea:AuthName },
# $CIPHERS{ des:AuthName } etc.

use vars qw( %SECRET_KEYS );
# Stores secret keys for MD5 checksums and encryption for each auth realm in
# $SECRET_KEYS{ AuthName }.

#===============================================================================
# S E R V E R   S T A R T   I N I T I A L I Z A T I O N
#===============================================================================

BEGIN {
	my (@keyfile_vars, $keyfile_var);
	@keyfile_vars = grep {
		$_ =~ /PAM_SecretKeyFile$/
	} keys %{ Apache->server->dir_config() };
	
	foreach  $keyfile_var ( @keyfile_vars ) {
		my $keyfile ;
		$keyfile = Apache->server->dir_config( $keyfile_var );
		my $auth_name ; $auth_name = $keyfile_var;
		
		$auth_name =~ s/PAM_SecretKeyFile$//;
		unless ( open( KEY, "<$keyfile" ) ) {
			Apache::log_error( "Could not open keyfile for $auth_name in file $keyfile" );
		} else {
			$SECRET_KEYS{ $auth_name } = <KEY>;
		close KEY;
		}
	}
}

#===============================================================================
# P E R L D O C
#===============================================================================

=head1 NAME

Apache::AuthCookiePAM - An AuthCookie module backed by a PAM .

=head1 VERSION

	$Revision: 1.0 $

=head1 SYNOPSIS

AuthCookiePAM.pm  view on Meta::CPAN

	<Files LOGIN>
		AuthType Apache::AuthCookiePAM
		AuthName WhatEver
		SetHandler perl-script
		PerlHandler Apache::AuthCookiePAM->login
	</Files>

	<Files ChangePwd>
		AuthType Apache::AuthCookiePAM
		AuthName WhatEver
		SetHandler perl-script
		PerlHandler Apache::AuthCookiePAM->changepwd
	</Files>

=head1 DESCRIPTION

This module is an authentication handler that uses the basic mechanism 
provided by Apache::AuthCookie with PAM (based on DBI) .  It is based on
two tokens being provided, a username and password, which can be any 
strings (there are no illegal characters for either).  The username is 
used to set the remote user as if Basic Authentication was used.

On an attempt to access a protected location without a valid cookie being
provided, the module prints an HTML login form (produced by a CGI or any
other handler; this can be a static file if you want to always send people
to the same entry page when they log in).  This login form has fields for
username and password.  On submitting it, the username and password are verfied 
using PAM. If this succeeds, the user is issued a ticket.  This ticket contains 
the username, an issue time, an expire time, and an MD5 checksum of those and a 
secret key for the server.  It can optionally be encrypted before returning it 
to the client in the cookie;
encryption is only useful for preventing the client from seeing the expire
time.  If you wish to protect passwords in transport, use an SSL-encrypted
connection.  The ticket is given in a cookie that the browser stores.

After a login the user is redirected to the location they originally wished
to view (or to a fixed page if the login "script" was really a static file).

On this access and any subsequent attempt to access a protected document, the
browser returns the ticket to the server.  The server unencrypts it if
encrypted tickets are enabled, then extracts the username, issue time, expire
time and checksum.  A new checksum is calculated of the username, issue time,
expire time and the secret key again; if it agrees with the checksum that
the client supplied, we know that the data has not been tampered with.  We
next check that the expire time has not passed.  If not, the ticket is still
good, so we set the username.

Authorization checks then check that any "require valid-user" . If checks pass, 
the document requested is displayed.

If a ticket has expired or is otherwise invalid it is cleared in the browser
and the login form is shown again.

=cut

#===============================================================================
# P R I V A T E   F U N C T I O N S
#===============================================================================

#-------------------------------------------------------------------------------
# _log_not_set -- Log that a particular authentication variable was not set.

sub _log_not_set($$)
{
	my( $r, $variable ) = @_;
	my $auth_name; $auth_name = $r->auth_name;
	$r->log_error( "Apache::AuthCookiePAM: $variable not set for auth realm
$auth_name", $r->uri );
}

#-------------------------------------------------------------------------------
# _dir_config_var -- Get a particular authentication variable.

sub _dir_config_var($$)
{
	my( $r, $variable ) = @_;
	my $auth_name; $auth_name = $r->auth_name;
	return $r->dir_config( "$auth_name$variable" );
}

#-------------------------------------------------------------------------------
# _config_vars -- Gets the config variables from the dir_config and logs
# errors if required fields were not set, returns undef if any of the fields
# had errors or a hash of the values if they were all OK.  Takes a request
# object.

sub _config_vars($)
{
	my( $r ) = @_;

	my %c; # config variables hash

=head1 APACHE CONFIGURATION DIRECTIVES

All configuration directives for this module are passed in PerlSetVars.  These
PerlSetVars must begin with the AuthName that you are describing, so if your
AuthName is PrivateBankingSystem they will look like:

	PerlSetVar ProvateBankingSystemLoginScript /bvsm/login.pl


See also L<Apache::Authcookie> for the directives required for any kind
of Apache::AuthCookie-based authentication system.

In the following descriptions, replace "WhatEver" with your particular
AuthName.  The available configuration directives are as follows:

=over 4

=item C<WhatEverPAM_SecretKeyFile>

The file that contains the secret key (on the first line of the file).  This
is required and has no default value.  This key should be owned and only
readable by root.  It is read at server startup time.  The key should be long
and fairly random.  If you want, you can change it and restart the server,
(maybe daily), which will invalidate all prior-issued tickets.

This directive MUST be set before the PerlModule line that loads this module,
because the secret key file is read immediately (at server start time).  This
is so you can have it owned and only readable by root even though Apache
then changes to another user.

=cut

	unless (
	   $c{ PAM_secretkeyfile } = _dir_config_var $r, 'PAM_SecretKeyFile'
	) {
		_log_not_set $r, 'PAM_SecretKeyFile';
		return undef;
	}

=item C<WhatEverPAM_SessionLifetime>

How long tickets are good for after being issued.  Note that presently
Apache::AuthCookie does not set a client-side expire time, which means that
most clients will only keep the cookie until the user quits the browser.
However, if you wish to force people to log in again sooner than that, set
this value.  This can be 'forever' or a life time specified as:

	DD-hh-mm-ss -- Days, hours, minute and seconds to live.

This is not required and defaults to '00-24-00-00' or 24 hours.

=cut

	$c{ PAM_sessionlifetime }
	   = _dir_config_var( $r, 'PAM_SessionLifetime' ) || '00-24-00-00';

=item C<WhatEverPAM_EncryptionType>

What kind of encryption to use to prevent the user from looking at the fields
in the ticket we give them.  This is almost completely useless, so don't
switch it on unless you really know you need it.  It does not provide any
protection of the password in transport; use SSL for that.  It can be 'none',
'des', 'idea', 'blowfish', or 'blowfish_pp'.

This is not required and defaults to 'none'.

=cut

	$c{ PAM_encryptiontype } = _dir_config_var( $r, 'PAM_EncryptionType' )
	            || 'none';
	# If we used encryption we need to pull in Crypt::CBC.
	if ( $c{ PAM_encryptiontype } ne 'none' ) {
		require Crypt::CBC;
	}

=item C<WhatEverPAM_service>

The service that will be using PAM libraries for authentication.
These will be one of the services configured in  /etc/pam.conf or /etc/pam.d/<service>

This directive defaults to "login"

=cut

	$c{ PAM_service } = _dir_config_var ( $r, 'PAM_service' ) || 'login';

	return %c;
}

#-------------------------------------------------------------------------------
# _now_year_month_day_hour_minute_second -- Return a string with the time in
# this order separated by dashes.

sub _now_year_month_day_hour_minute_second()
{
	return sprintf '%04d-%02d-%02d-%02d-%02d-%02d', Today_and_Now;