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[LON-CAPA] /
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lonracc.pm
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1.6:
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Mon Oct 21 19:15:10 2002 UTC (21 years, 9 months ago) by
bowersj2
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This took way longer then it should have.
lonracc and lontokacc will now be accepting when one of two conditions
is met:
* The double-reverse lookup, according to $r->get_remote_host(REMOTE_DOUBLE_REV)
is successful. This is identical to before.
* The claimed host is the same as the current server, which works even with
wonky /etc/hosts files.
I was initially worried this might be a potential security problem, but I do
not believe it is. The reason is that this clause ONLY comes into effect
when you're trying to spoof yourself as the server you are talking to. Even
if you succeed, the server will then proceed to send itself a subscription
request, which is not a big deal, PLUS the reason this is occuring in the
first place is that the name maps back to 127.0.0.1, SO this request will
go through the local interface anyhow, meaning Mr. Remote Attacker can't even
see the subscription request that wouldn't help him anyhow.
So in the end, all this does is hypothetically allow an attacker to cause a
server machine to subscribe itself to resources it hosts. This does not give
the hypothetical attacker any benefit. Thus, this is not a security hole.
1: # The LearningOnline Network
2: # Access Handler for File Transfers
3: #
4: # $Id: lonracc.pm,v 1.6 2002/10/21 19:15:10 bowersj2 Exp $
5: #
6: # Copyright Michigan State University Board of Trustees
7: #
8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
9: #
10: # LON-CAPA is free software; you can redistribute it and/or modify
11: # it under the terms of the GNU General Public License as published by
12: # the Free Software Foundation; either version 2 of the License, or
13: # (at your option) any later version.
14: #
15: # LON-CAPA is distributed in the hope that it will be useful,
16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18: # GNU General Public License for more details.
19: #
20: # You should have received a copy of the GNU General Public License
21: # along with LON-CAPA; if not, write to the Free Software
22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23: #
24: # /home/httpd/html/adm/gpl.txt
25: #
26: # http://www.lon-capa.org/
27: #
28: # (lonacc: Cookie Based Access Handler
29: # 5/21/99,5/22,5/29,5/31,6/15 Gerd Kortemeyer)
30: # 6/16,6/18,7/3,
31: # 6/30/00 Gerd Kortemeyer
32:
33: package Apache::lonracc;
34:
35: use strict;
36: use Apache::Constants qw(:common :remotehost);
37: use Apache::lonnet();
38: use Apache::File();
39:
40: sub subscribed {
41: my ($filename,$id) = @_;
42: my $found=0;
43: my $expr='^'.$id.':'.$Apache::lonnet::hostip{$id}.':';
44: $expr =~ s/\./\\\./g;
45: my $sh;
46: if ($sh=Apache::File->new("$filename.subscription")) {
47: while (my $subline=<$sh>) { if ($subline =~ /$expr/) { $found=1; } }
48: $sh->close();
49: }
50: return $found;
51: }
52:
53: sub handler {
54: my $r = shift;
55: my $reqhost = $r->get_remote_host(REMOTE_DOUBLE_REV);
56: if (!$reqhost && $r->get_remote_host(REMOTE_NOLOOKUP) eq $r->get_server_name()) {
57: $reqhost = $r->get_server_name();
58: }
59: unless ($reqhost)
60: $r->log_reason("Spoof request from ".$ENV{'REMOTE_ADDR'});
61: return FORBIDDEN;
62: }
63: my $readline;
64: my $lontabdir=$r->dir_config('lonTabDir');
65: {
66: my $fh;
67: unless ($fh=Apache::File->new("$lontabdir/hosts.tab")) {
68: $r->log_reason("Could not find host tab file");
69: return FORBIDDEN;
70: }
71: while ($readline=<$fh>) {
72: my ($id,$domain,$role,$name,$ip)=split(/:/,$readline);
73: if ($name =~ /$reqhost/i) {
74: my $filename=$r->filename;
75: if ((-e "$filename.$id") ||
76: &subscribed($filename,$id) ||
77: ($filename=~/\.meta$/)) {
78: return OK;
79: } else {
80: $r->log_reason("$id not subscribed", $r->filename);
81: return FORBIDDEN;
82: }
83: }
84: }
85:
86: }
87: $r->log_reason("Invalid request for file transfer from $reqhost",
88: $r->filename);
89: return FORBIDDEN;
90: }
91:
92: 1;
93: __END__
94:
95: =head1 NAME
96:
97: Apache::lonracc - Access Handler for File Transfers
98:
99: =head1 SYNOPSIS
100:
101: Invoked by /etc/httpd/conf/loncapa.conf:
102:
103: <LocationMatch "^/raw.*">
104: PerlAccessHandler Apache::lonracc
105: </LocationMatch>
106:
107: =head1 INTRODUCTION
108:
109: This module enables authentication for file transfers and works
110: against the /res tree.
111:
112: Only lond invokes the /raw namespace through its subscribe function.
113:
114: This is part of the LearningOnline Network with CAPA project
115: described at http://www.lon-capa.org.
116:
117: =head1 HANDLER SUBROUTINE
118:
119: This routine is called by Apache and mod_perl.
120:
121: =over 4
122:
123: =item *
124:
125: Determine requesting host
126:
127: =item *
128:
129: See whether or not the requesting host is subscribed.
130:
131: =item *
132:
133: Respond with status of request and make log entry in case of unallowed
134: access.
135:
136: =back
137:
138: =cut
139:
140:
141:
142:
143:
144:
145:
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