Annotation of loncom/lonlocal.pm, revision 1.6
1.2 foxr 1: #
1.6 ! foxr 2: # $Id: lonlocal.pm,v 1.5 2004/06/17 09:27:23 foxr Exp $
1.2 foxr 3: #
4: # Copyright Michigan State University Board of Trustees
5: #
6: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
7: #
8: # LON-CAPA is free software; you can redistribute it and/or modify
9: # it under the terms of the GNU General Public License as published by
10: # the Free Software Foundation; either version 2 of the License, or
11: # (at your option) any later version.
12: #
13: # LON-CAPA is distributed in the hope that it will be useful,
14: # but WITHOUT ANY WARRANTY; without even the implied warranty of
15: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16: # GNU General Public License for more details.
17: #
18: # You should have received a copy of the GNU General Public License
19: # along with LON-CAPA; if not, write to the Free Software
20: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21: #
22: # /home/httpd/html/adm/gpl.txt
23: #
24: # http://www.lon-capa.org/
25: #
26: package lonlocal;
27:
28: #
29: # Module that provides support for local connections between secure
30: # lonc and secure lond.
31: #
32: # A local connection exchanges one-time session keys through a
33: # file that is written in the certificate directory by lonc and
34: # read/deleted by lond. The file is created with permissions
35: # rw------- (0600) to prevent it from being snooped unless the system
36: # itself has been broken. In addition the file will not be around
37: # for very long so it will be hard to find.
38: #
39:
40: use strict;
41:
42: # CPAN/standard modules
43:
44: use Crypt::IDEA;
1.3 foxr 45: use Fcntl;
1.2 foxr 46:
47: # LONCAPA modules
48:
49: use LONCAPA::Configuration;
50:
51: # Global variables:
52:
53: my $perlvar; # Refers to the apache perlsetvar hash.
1.3 foxr 54: my $pathsep = "/"; # Unix path seperator
55: my $fileindex = 0; # Per process lonc uniquifier.
56: my $lastError; # Reason for last failure.
57:
1.2 foxr 58:
1.5 foxr 59: # Debugging:
60:
1.6 ! foxr 61: my $DEBUG = 0;
1.5 foxr 62:
63: sub Debug {
64: my $msg = shift;
65: print STDERR "$msg\n";
66: }
67:
1.2 foxr 68: # Initialization
69:
70: $perlvar = LONCAPA::Configuration::read_conf('loncapa.conf');
71:
72:
73: #------------------------------------------------------------------------
74: #
1.5 foxr 75: # Name CreateCipherKey
1.2 foxr 76: # Description: Create an encryption key.
77: # Returns: The key.
78: #
79: sub CreateCipherKey {
80:
81: my $keylength;
82: my $binaryKey;
83: my $cipherkey;
84:
1.5 foxr 85: # we'll use the output of /dev/urandom to produce our key.
1.2 foxr 86: # On a system with decent entropy, this ought to be much more
87: # random than all the playing that used to be done to get a key.
1.5 foxr 88: # On a system with not so decent entropy we'll still get an ok key.
89: # My concern with /dev/random is that we may block for an indefinite
90: # time period...where for us decent keys are probably good enough.
1.2 foxr 91:
92: $keylength = IDEA::keysize();
1.5 foxr 93: open(RANDOM, "</dev/urandom");
1.2 foxr 94: sysread(RANDOM, $binaryKey, $keylength);
95: close RANDOM;
96:
97: # The key must be returned in a stringified form in order to be
98: # transmitted to the peer:
99:
100: my $hexdigits = $keylength*2; # Assume 8 bits/byte.
101: my $template = "H".$hexdigits;
102: $cipherkey = unpack($template, $binaryKey);
103:
104: return $cipherkey;
105: }
106:
107: #------------------------------------------------------------------------
108: #
109: # Name CreateKeyFile
110: # Description Creates a private key file and writes an IDEA key into it.
111: #
112: # Returns
113: # A two element list containing:
114: # - The private key that was created
115: # - The full path to the file that contains it.
1.3 foxr 116: # or undef on failure.
1.2 foxr 117: sub CreateKeyFile {
118:
119: # To create the file we need some perlvars to tell us where the
120: # certificate directory. We'll make a file named localkey.$pid
121: # there, and set the mode before writing into it.
122: #
1.3 foxr 123: $fileindex++;
124: my $CertificateDir = $perlvar->{lonCertificateDirectory};
1.5 foxr 125: my $Filename = $CertificateDir.$pathsep.".$fileindex.".$$;
1.3 foxr 126:
127: # If this file already exists, this is a recoverable error... we just
128: # delete the earlier incarnation of the file.
129:
130: if (-w $Filename) {
131: unlink $Filename;
132: }
133:
134: # If the file still exists this is really really bad:
135: # It most likely means someone has been devious enough to drop a key file
136: # in place to attemp to spoof the lond. We'll fail in that case hoping
137: # that the user looks at the log to figure out that local connections
138: # are failing.
139:
140: if( -e $Filename) {
141: $lastError = "Key file already exists after deletion probably a spoof!";
142: return undef;
143: }
144: # Now we can create the file we use sysopen in order to ensure
145: # the file is created with the appropriate locked down permissions.
146:
147: if(! sysopen(KEYFILE, $Filename, O_CREAT | O_EXCL | O_WRONLY, 0600)) {
1.5 foxr 148: $lastError = "Creation of key file failed ".$!;
1.3 foxr 149: return undef;
150: }
151: # Create the key, write it to the file and close the file:
152:
153: my $key = CreateCipherKey();
154: print KEYFILE "$key\n";
155: close KEYFILE;
156:
1.5 foxr 157: return ($key, $Filename);
1.3 foxr 158:
1.2 foxr 159:
160: }
161:
162:
1.3 foxr 163: # Name ReadKeyFile
164: # Description Opens the private local key file and reads the IDEA key from it.
165: # Parameters
166: # Name Type Description
167: # Filename string path to key file
168: #
169: # NOTE:
170: # Reading the keyfile is a one-time thing. This sub destroys the
171: # keyfile after reading it to ensure the one-timedness of the keys they
172: # contain!!
173: # Returns
174: # On success the IDEA key that was written into the key fileon failure undef.
175: #
176: #
177: sub ReadKeyFile {
178: my $Filename = shift;
1.5 foxr 179: Debug("ReadKeyFile: $Filename");
180:
1.3 foxr 181:
182: if(! open(KEYFILE, "<$Filename")) {
1.5 foxr 183: Debug(" Open of $Filename failed\n");
1.3 foxr 184: $lastError = "Key file open failed";
185: return undef
186: }
187: my $key = <KEYFILE>;
1.5 foxr 188: chomp($key);
189: Debug(" Read key: $key");
1.3 foxr 190: close KEYFILE;
191: unlink $Filename;
192: #
193: # If the filename still exists some spoofer wrote it with the wrong
194: # permissions:
195: #
196: if(-e $Filename) {
1.5 foxr 197: Debug("File did not get deleted");
1.3 foxr 198: $lastError = "Key file still exists after unlink";
199: return undef;
200: }
201: #
202: # The IDEA key must be IDEA::keysize*2 characters
203: # long. If it isn't probably someone's trying to break us by
204: # hitting the timing hole between the file write and read...
205: # replacing our file... of course if they read this comment they'll
206: # be too smart to put an incorrectly sized file
207: #
1.5 foxr 208: my $keylen = length($key);
209: my $rightlen= IDEA::keysize()*2;
210: if($keylen != $rightlen) {
211: Debug("Key is incorrect length is $keylen sb $rightlen");
1.3 foxr 212: $lastError = "Key file has incorrect length";
213: return undef;
214: }
1.5 foxr 215: Debug("Returning key: $key to caller");
1.3 foxr 216: return $key;
217: }
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