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Apache-AuthCookiePAM

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#===============================================================================
#
# 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

	# In httpd.conf or .htaccess
	# This PerlSetVar MUST precede the PerlModule line because the
	# key is read in a BEGIN block when the module is loaded.
	PerlSetVar WhatEverPaM_SecretKeyFile /etc/httpd/acme.com.key

AuthCookiePAM.pm view on Meta::CPAN

=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;
}

#-------------------------------------------------------------------------------
# _percent_encode -- Percent-encode (like URI encoding) any non-alphanumberics
# in the supplied string.

sub _percent_encode($)
{
	my( $str ) = @_;
	$str =~ s/([^\w])/ uc sprintf '%%%02x', ord $1 /eg;
	return $str;
}

#-------------------------------------------------------------------------------
# _percent_decode -- Percent-decode (like URI decoding) any %XX sequences in
# the supplied string.

sub _percent_decode($)
{
	my( $str ) = @_;
	$str =~ s/%([0-9a-fA-F]{2})/ pack( "c",hex( $1 ) ) /ge;
	return $str;
}

#===============================================================================
# P U B L I C   F U N C T I O N S
#===============================================================================

#-------------------------------------------------------------------------------
# Take the credentials for a user and check that they match; if so, return
# a new session key for this user that can be stored in the cookie.
# If there is a problem, return a bogus session key.

sub authen_cred($$\@)
{
    my( $self, $r, @credentials ) ;
    ( $self, $r, @credentials ) = @_;

    my $auth_name; $auth_name = $r->auth_name;
    my %c ; %c = _config_vars $r;

    # Username goes in credential_0
    my $user; $user = $credentials[ 0 ];
    $user=~ tr/A-Z/a-z/;
    unless ( $user =~ /^.+$/ ) {
	$r->log_reason( "Apache::AuthCookiePAM: no username supplied for auth realm $auth_name", $r->uri );
        $r->subprocess_env('AuthenReason', 'No username provided. Try again.');
	return undef;
    }
    # Password goes in credential_1
    my $password; $password = $credentials[ 1 ];
    unless ( $password =~ /^.+$/ ) {
	$r->log_reason( "Apache::AuthCookiePAM: no password supplied for auth realm $auth_name", $r->uri );
        $r->subprocess_env('AuthenReason', 'No password provided. Try again.');
	return undef;
    }
    # service to be used for authentication
    my $service; $service = $c{PAM_service};
    my ($pamh,$res,$funcref);
    $funcref=create_conv_func($r,$user,$password); 
      
    ref($pamh = new Authen::PAM($service, $user,$funcref)) || die "Error code $pamh during PAM init!";
    # call auth module to authenticate user
    $res = $pamh->pam_authenticate;
    $funcref=0;
    if ( $res != PAM_SUCCESS()) {
        $r->log_error("ERROR: Authentication for $user Failed\n");
        $r->subprocess_env('AuthenReason', 'Authentication failed. Username/Password provided incorrect.');
        $pamh=0;
	undef $pamh;
        return undef;
    } 
    else { # Now check if account is valid
        $res = $pamh->pam_acct_mgmt();
	if ( $res == PAM_ACCT_EXPIRED() ) {
           $r->log_error("ERROR: Account for $user is locked. Contact your Administrator.\n");
           $r->subprocess_env('AuthenReason', 'Account for $user is locked. Contact your Administrator.');
           return 'bad';
	}
	if ( $res == PAM_NEW_AUTHTOK_REQD() ) {
           $r->log_error("ERROR: PAssword for $user expired. Change Password\n");
           $r->subprocess_env('AuthenReason', 'Password Expired. Please Change your password.');
	   return $r->auth_type->changepwd_form ($user);
	}
	if ( $res == PAM_SUCCESS() ) {
           # Create the expire time for the ticket.
           my $expire_time;
           # expire time in a zillion years if it's forever.
           if ( lc $c{ PAM_sessionlifetime } eq 'forever' ) {
              $expire_time = '9999-01-01-01-01-01';
           } else {
	      my( $deltaday, $deltahour, $deltaminute, $deltasecond ) = split /-/, $c{ PAM_sessionlifetime };
	      # Figure out the expire time.
	      $expire_time = sprintf( '%04d-%02d-%02d-%02d-%02d-%02d',
					Add_Delta_DHMS( Today_and_Now,
					                $deltaday, $deltahour,
							$deltaminute, $deltasecond ));
          }

	   # Now we need to %-encode non-alphanumberics in the username so we
	   # can stick it in the cookie safely.  *** DEBUG *** check this
	   my $enc_user; $enc_user = _percent_encode $user;

	   # OK, now we stick the username and the current time and the expire
	   # time together to make the public part of the session key:
	   my $current_time; $current_time = _now_year_month_day_hour_minute_second;
	   my $public_part; $public_part = "$enc_user:$current_time:$expire_time";

	   # Now we calculate the hash of this and the secret key and then
	   # calculate the hash of *that* and the secret key again.
	   my $secret_key; $secret_key = $SECRET_KEYS{ $auth_name };
	   unless ( defined $secret_key ) {
		$r->log_reason( "Apache::AuthCookiePAM: didn't have the secret key for auth realm $auth_name", $r->uri );
		return 'bad';
	   }
	   my $hash ; $hash = md5_hex( join ':', $secret_key, md5_hex(
	                  	join ':', $public_part, $secret_key
	                     ) );

	   # Now we add this hash to the end of the public part.
	   my $session_key; $session_key = "$public_part:$hash";

	   # Now we encrypt this and return it.
	   my $encrypted_session_key;
	   if ( $c{ PAM_encryptiontype } eq 'none' ) {
		$encrypted_session_key = $session_key;
	   } elsif ( lc $c{ PAM_encryptiontype } eq 'des'      ) {
		$CIPHERS{ "des:$auth_name"      }
		   ||= Crypt::CBC->new( $secret_key, 'DES'      );
		$encrypted_session_key = $CIPHERS{
			"des:$auth_name"
		}->encrypt_hex( $session_key );
	   } elsif ( lc $c{ PAM_encryptiontype } eq 'idea'     ) {
		$CIPHERS{ "idea:$auth_name"      }
		   ||= Crypt::CBC->new( $secret_key, 'IDEA'     );
		$encrypted_session_key = $CIPHERS{
			"idea:$auth_name"
		}->encrypt_hex( $session_key );
	   } elsif ( lc $c{ PAM_encryptiontype } eq 'blowfish' ) {
		$CIPHERS{ "blowfish:$auth_name" }
		   ||= Crypt::CBC->new( $secret_key, 'Blowfish' );
		$encrypted_session_key = $CIPHERS{
			"blowfish:$auth_name"
		}->encrypt_hex( $session_key );
	   }
	   $pamh=0;
	   undef $pamh;
	   return $encrypted_session_key;
        }
    }
}


#-------------------------------------------------------------------------------
# Conversation function for PAM - authentication and change of password
sub create_conv_func 
{
   my ($r,$user,$pass,$newpass,$confpass);
   ($r,$user,$pass,$newpass,$confpass) = @_;

   my $state; $state = 0;

AuthCookiePAM.pm view on Meta::CPAN

      };
}

#-------------------------------------------------------------------------------
# Take a session key and check that it is still valid; if so, return the user.

sub authen_ses_key($$$)
{
	my( $self, $r, $encrypted_session_key ) = @_;

	my $auth_name ; $auth_name = $r->auth_name;

	# Get the configuration information.
	my %c; %c = _config_vars $r;

	# Get the secret key.
	my $secret_key; $secret_key = $SECRET_KEYS{ $auth_name };
	unless ( defined $secret_key ) {
		$r->log_reason( "Apache::AuthCookiePAM: didn't the secret key from for auth realm $auth_name", $r->uri );
		return undef;
	}
	
	# Decrypt the session key.
	my $session_key;
	if ( $c{ PAM_encryptiontype } eq 'none' ) {
		$session_key = $encrypted_session_key;
	} else {
		# Check that this looks like an encrypted hex-encoded string.
		unless ( $encrypted_session_key =~ /^[0-9a-fA-F]+$/ ) {
			$r->log_reason( "Apache::AuthCookiePAM: encrypted session key $encrypted_session_key doesn't look like it's properly hex-encoded for auth realm $auth_name", $r->uri );
			return undef;
		}

		# Get the cipher from the cache, or create a new one if the
		# cached cipher hasn't been created, & decrypt the session key.
		my $cipher;
		if ( lc $c{ PAM_encryptiontype } eq 'des' ) {
			$cipher = $CIPHERS{ "des:$auth_name" }
			   ||= Crypt::CBC->new( $secret_key, 'DES' );
		} elsif ( lc $c{ PAM_encryptiontype } eq 'idea' ) {
			$cipher = $CIPHERS{ "idea:$auth_name" }
			   ||= Crypt::CBC->new( $secret_key, 'IDEA' );
		} elsif ( lc $c{ PAM_encryptiontype } eq 'blowfish' ) {
			$cipher = $CIPHERS{ "blowfish:$auth_name" }
			   ||= Crypt::CBC->new( $secret_key, 'Blowfish' );
		} elsif ( lc $c{ PAM_encryptiontype } eq 'blowfish_pp' ) {
			$cipher = $CIPHERS{ "blowfish_pp:$auth_name" }
			   ||= Crypt::CBC->new( $secret_key, 'Blowfish_PP' );
		} else {
			$r->log_reason( "Apache::AuthCookiePAM: unknown encryption type $c{ PAM_encryptiontype } for auth realm $auth_name", $r->uri );
			return undef;
		}
		$session_key = $cipher->decrypt_hex( $encrypted_session_key );
	}
	
	# Break up the session key.
	my( $enc_user, $issue_time, $expire_time, $supplied_hash )
	   = split /:/, $session_key;
	# Let's check that we got passed sensible values in the cookie.
	unless ( $enc_user =~ /^[a-zA-Z0-9_\%]+$/ ) {
		$r->log_reason( "Apache::AuthCookiePAM: bad percent-encoded user $enc_user recovered from session ticket for auth_realm $auth_name", $r->uri );
		return undef;
	}
	# decode the user
	my $user; $user = _percent_decode $enc_user;
	unless ( $issue_time =~ /^\d{4}-\d{2}-\d{2}-\d{2}-\d{2}-\d{2}$/ ) {
		$r->log_reason( "Apache::AuthCookiePAM: bad issue time $issue_time recovered from ticket for user $user for auth_realm $auth_name", $r->uri );
		return undef;
	}
	unless ( $expire_time =~ /^\d{4}-\d{2}-\d{2}-\d{2}-\d{2}-\d{2}$/ ) {
		$r->log_reason( "Apache::AuthCookiePAM: bad expire time $expire_time recovered from ticket for user $user for auth_realm $auth_name", $r->uri );
		return undef;
	}
	unless ( $supplied_hash =~ /^[0-9a-fA-F]{32}$/ ) {
		$r->log_reason( "Apache::AuthCookiePAM: bad hash $supplied_hash recovered from ticket for user $user for auth_realm $auth_name", $r->uri );
		return undef;
	}

	# Calculate the hash of the user, issue time, expire_time and
	# the secret key and then the hash of that and the secret key again.
	my $hash; $hash = md5_hex( join ':', $secret_key, md5_hex(
		join ':', $enc_user, $issue_time, $expire_time, $secret_key
	) );

	# Compare it to the hash they gave us.
	unless ( $hash eq $supplied_hash ) {
		$r->log_reason( "Apache::AuthCookiePAM: hash in cookie did not match calculated hash of contents for user $user for auth realm $auth_name", $r->uri );
		return undef;
	}

	# Check that their session hasn't timed out.
	if ( _now_year_month_day_hour_minute_second gt $expire_time ) {
		$r->log_reason( "Apache:AuthCookiePAM: expire time $expire_time has passed for user $user for auth realm $auth_name", $r->uri );
		return undef;
	}

	# If we're being paranoid about timing-out long-lived sessions,
	# check that the issue time + the current (server-set) session lifetime
	# hasn't passed too (in case we issued long-lived session tickets
	# in the past that we want to get rid of). *** DEBUG ***
	# if ( lc $c{ PAM_AlwaysUseCurrentSessionLifetime } eq 'on' ) 

	# They must be okay, so return the user.
	return $user;
}


sub changepwd_form 
{  
  my $self; $self = shift;
  my $user; $user = shift;

  my $r; $r = Apache->request or die "no request";
  $r->log_error(" $self ");
  $r->subprocess_env("AuthenChangePwdUser","$user");
  my $auth_name; $auth_name = $r->auth_name;

  my %args; %args = $r->method eq 'POST' ? $r->content : $r->args;

  $self->_convert_to_get($r, \%args) if $r->method eq 'POST';

  # There should be a PerlSetVar directive that gives us the URI of
  # the script to execute for the login form.
  
  my $script;

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