Apache PerlAuthzHandler and form POST vars - apache

Question

I have a mod_perl PerlAuthzHandler authorizing access to directories served by Apache2. In terms of controlling access it is working well.
A side effect, though, is that it seems to be preventing POST form variables from being available to PHP apps in the protected locations. At least when I comment out the PerlAuthzHandler and reload Apache the PHP app functions again. I think either the full environment is not being inherited by Perl or Perl is sending a cleansed environment on.
Is it possible to ensure that all POST variables are available to the PHP application after authorization?
Details
User authentication is managed by simplesamlphp on this box, the SP, and ADFS, the IdP. The addition to the simplesamlphp installation is the use of PerlAuthzHandler.
Apache configuration
The Apache configuration for the location in question looks like this:
<Location /activity>
ErrorDocument 401 "/simplesaml/authmemcookie.php"
AuthName "MCLAnet"
AuthType Cookie
Require valid-user
PerlSetvar Auth_memCookie_SessionTableSize "40"
PerlAuthzHandler My::simple
PerlSetVar VALID_GROUP_EXPR "status-acad or staff-g"
</Location>
Authorization handler
The authorization handler retrieves group memberships recorded in setting up the session and compared to a VALID_GROUP_EXPRESSION in the PerlSetVar:
#! /usr/bin/perl
package My::simple;
# Version 1.0 MCLA CSS
use Apache2::Access ();
use Apache2::RequestUtil ();
# load modules that are going to be used
use Data::Dumper;
use CGI qw(:standard);
use CGI::Cookie;
use Cache::Memcached;
use PHP::Serialization qw(serialize unserialize);
# compile (or import) constants
use Apache2::Const -compile => qw(OK FORBIDDEN);
$debug=0;
$debug_file="/tmp/xxx";
dmp('prerun',('test'));
sub handler {
my $r = shift;
my $user = $r->user;
dmp('0 user',$user);
# ------------------------ get valid group(s) for this session
my $valid_group_expr=$r->dir_config("VALID_GROUP_EXPR");
dmp('1 valid group list',$valid_group_expr);
# -- get the session cooke to retrieve the session <ID>
$query = new CGI;
# fetch existing cookies
my %cookies = CGI::Cookie->fetch;
# dmp('Cookies',%cookies);
my $ID = $cookies{'SimpleSAMLSessionID'}->value;
dmp('2 SimpleSAMLSessionID value',$ID);
my $SessionID='simpleSAMLphp.session.' . $ID;
# -- use the session ID to look up the value of memcached key simpleSAMLphp.session.<ID>
my $cache = new Cache::Memcached {
'servers' => ['127.0.0.1:11211'],
'compress_threshold' => 10_000,
};
# Get the value from cache:
my $value = $cache->get($SessionID);
# dmp('mamcache value',($value));
# -- use the value data to find the groups
my $hashref = unserialize($value);
# dmp('mamcache unserialized',($hashref));
my %hash = %{ $hashref };
%hash = % { $hash {'data'}{chr(0) . 'SimpleSAML_Session' . chr(0) . 'authData'}{'default-sp'}{'Attributes'} };
my #groups = # { $hash{'groups'} };
dmp("3 Comparing $valid_group_expr to", \#groups);
my $result=evaluate($valid_group_expr,#groups);
if ($result) {
dmp("this guy oK",$result);
return Apache2::Const::HTTP_OK;
}
dmp("blowing this guy off",$result);
$r->log_reason("Not a member of group " . $valid_group_expr);
return Apache2::Const::FORBIDDEN;
# return Apache2::Const::HTTP_FORBIDDEN;
# return Apache2::Const::HTTP_OK;
# return Apache2::Const::DECLINED;
}
# ======================= utility functions
# evaluate returns the boolean value of the expression $expr
# after substituting membership information in #groups
#
# valid operators are
#
# &&, and, AND logical AND
# ||, or, OR logical OR
# !, NOT, not logical NOT
#
# expression must be infix and precidence can be indicated by ()
sub evaluate {
my ($expr,#groups)=#_;
# print "$expr\n";
# print Dumper(\%group_hash);
# operator tokens
my %token_hash = (
'(' => '(',
')' => ')',
'AND' => '&&',
'and' => '&&',
'or' => '||',
'OR' => '||',
'!' => '!',
'not' => '!',
'NOT' => '!',
) ;
# add the group array into the token hash as TRUEs
foreach $v (#groups) {
$v=~s/ /_/g;
$token_hash{$v} = 1;
}
dmp('merged hash',\%token_hash);
# merge the two hashes into %token_hash
# foreach my $tkey ( keys %group_hash) { $token_hash{$tkey} = $group_hash{$tkey}; }
# print Dumper(\%token_hash);
$expr=~s/\(/ ( /g;
$expr=~s/\)/ ) /g;
$expr=~s/\!/ ! /g;
# print "$expr\n";
my #expr_hash=split (/ /,$expr);
$expr='';
foreach my $t (#expr_hash) {
if ($t ne '') {
if (exists ($token_hash{$t})) { $t = $token_hash{$t} } else {$t = 0;}
$expr = $expr . "$t ";
}
}
dmp("expression",$expr);
my $result=0;
my $assignment="\$result = $expr;";
dmp("assignment",$assignment);
eval($assignment);
dmp("result",$result);
return $result;
}
# debug dump structure funcion
sub dmp {
if ($debug == 1) {
my ($label,#value) = #_;
my $temp = Dumper(#value);
open (T, ">>$debug_file"); # || die "Can't open $debug_file: $!\n";
print T "$label: $temp\n";
close (T);
}
}
1;
Failing PHP script
The simple PHP form below displays no value when the Perl authorization is enabled. If I comment out the PerlAuthzHandler line both $_POST'[submit'] and $_POST['in1'] are set.
<?php
if (isset($_POST['submit'])) { print_r($_POST); }
$form=<<<EOT
<form name="test" action="y.php" method="post">
<input name="in1">
<input type="submit" name="submit">
</form>
EOT;
print $form;
?>
Again, authentication (simplesamlphp/ADFS) and authorization both work as expected. The exception is that when authorization is used no $_POST variables are available.

Answer 1

RESOLUTION
As often happens the problem was of my own making. One of the kind monks at perlmonks.org pointed out that the Perl handler contained the line:
$query = new CGI;
Removing that did it. Since I was in fact only accessing but not changing anything there was no point to it and in fact $query was never used.