1: #!/usr/bin/perl
2:
3: # The Learning Online Network with CAPA
4: #
5: # Copyright Michigan State University Board of Trustees
6: #
7: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
8: #
9: # LON-CAPA is free software; you can redistribute it and/or modify
10: # it under the terms of the GNU General Public License as published by
11: # the Free Software Foundation; either version 2 of the License, or
12: # (at your option) any later version.
13: #
14: # LON-CAPA is distributed in the hope that it will be useful,
15: # but WITHOUT ANY WARRANTY; without even the implied warranty of
16: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17: # GNU General Public License for more details.
18: #
19: # You should have received a copy of the GNU General Public License
20: # along with LON-CAPA; if not, write to the Free Software
21: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22: #
23: # /home/httpd/html/adm/gpl.txt
24: #
25: # http://www.lon-capa.org/
26: #
27: # lchtmldir - LONC-CAPA setuid script to:
28: # o If necessary, add a public_html directory
29: # to the specified user home directory.
30: # o Set the permissions according to the authentication type.
31: #
32: # Motivations:
33: # Originally, account creation would create a public_html
34: # directory for unix authorized people only. It is possible to have
35: # Kerberos, internal and locally authorized 'users' which may be authors
36: # and hence need a properly owned an protected public_html directory
37: # to serve as their construction space.
38: #
39: # Author:
40: # Ron Fox
41: # NSCL
42: # Michigan State University8
43: # East Lansing, MI 48824-1321
44:
45: # General flow of control:
46: # 1. Validate process state (must be run as www).
47: # 2. Validate parameters: Need two parameters:
48: # o Homedir - Home diretory of user
49: # o Username - Name of the user.
50: # o AuthMode - Authentication mode, can be:
51: # - unix
52: # - internal
53: # - krb4
54: # - localauth
55: # 3. Untaint the usename and home directory
56: #
57: # 4. As root if necessary, create $Homedir/public_html
58: # 5. Set ownership/permissions according to authentication mode (AuthMode)
59: # - unix - ~owner:www/2775
60: # - krb4 - ~owner:www/2775
61: # - internal - www:www/2775
62: # - local - www:www/2775
63: #
64:
65: #
66: # Take a few precautions to be sure that we're not vulnerable to trojan
67: # horses and other fine issues:
68: #
69: use strict;
70:
71: $ENV{'PATH'} = '/bin:/usr/bin:/usr/local/sbin:/home/httpd/perl';
72: delete @ENV{qw{IFS CDPATH ENV BASH_ENV}};
73:
74: my $DEBUG = 0; # .nonzero -> Debug printing enabled.
75:
76:
77: # If the UID of the running process is not www exit with error.
78:
79: if ($DEBUG) {
80: print("Checking uid...\n");
81: }
82: my $wwwid = getpwnam('www');
83: &DisableRoot;
84: if($wwwid != $>) {
85: if ($DEBUG) {
86: print("User ID incorrect. This program must be run as user 'www'\n");
87: }
88: exit 1; # Exit with error status.
89: }
90:
91: # There must be three 'command line' parameters. The first
92: # is the home directory of the user.
93: # The second is the name of the user. This is only referenced
94: # in code branches dealing with unix mode authentication.
95: # The last is the authentication mode which must be one of unix, internal
96: # krb4 or localauth.
97: # If there is an error in the argument count or countents, we exit with an
98: # error.
99:
100: if ($DEBUG) {
101: print("Checking parameters: \n");
102: }
103: if(@ARGV != 3) {
104: if($DEBUG) {
105: print("Error: lchtmldir need 3 parameters \n");
106: }
107: exit 2;
108: }
109: my ($dir,$username,$authentication) = @ARGV;
110:
111: if($DEBUG) {
112: print ("Directory = $dir \n");
113: print ("User = $username \n");
114: print ("Authmode = $authentication \n");
115:
116: }
117:
118: if( $authentication ne "unix:" &&
119: $authentication ne "internal:" &&
120: $authentication !~ /^krb(4|5):(.*)/ &&
121: $authentication ne "localauth:") {
122: if($DEBUG) {
123: print("Invalid authentication parameter: ".$authentication."\n");
124: print("Should be one of: unix, internal, krb4, localauth\n");
125: }
126: exit 3;
127: }
128:
129: # Untaint the username.
130:
131: my $match = $username =~ /^(\w+)$/;
132: my $patt = $1;
133:
134: if($DEBUG) {
135: print("Username word match flag = ".$match."\n");
136: print("Match value = ".$patt."\n");
137: }
138:
139: my $safeuser = $patt;
140: if($DEBUG) {
141: print("Save username = $safeuser \n");
142: }
143: if(($username ne $safeuser) or ($safeuser!~/^[A-za-z]/)) {
144: if($DEBUG) {
145: print("User name $username had illegal characters\n");
146: }
147: exit 4;
148: }
149:
150: #untaint the base directory require that the dir contain only
151: # alphas, / numbers or underscores, and end in /$safeuser
152:
153: $dir =~ /(^([\w\/]+))/;
154:
155: my $dirtry1 = $1;
156:
157: $dir =~ /$\/$safeuser/;
158: my $dirtry2 = $1;
159:
160: if(($dirtry1 ne $dir) or ($dirtry2 ne $dir)) {
161: if ($DEBUG) {
162: print("Directory $dir is not a valid home for $safeuser\n");
163: }
164: exit 5;
165: }
166:
167:
168: # As root, create the directory.
169:
170: my $homedir = $dirtry1;
171: my $fulldir = $homedir."/public_html";
172:
173: if($DEBUG) {
174: print("Full directory path is: $fulldir \n");
175: }
176: if(!( -e $dirtry1)) {
177: if($DEBUG) {
178: print("User's home directory $dirtry1 does not exist\n");
179: }
180: if ($authentication eq "unix:") {
181: exit 6;
182: }
183: }
184: &EnableRoot;
185:
186: &System("/bin/mkdir -p $fulldir") unless (-e $fulldir);
187: unless(-e $fulldir."/index.html") {
188: open OUT,">".$fulldir."/index.html";
189: print OUT<<END;
190: <html>
191: <head>
192: <title>$safeuser</title>
193: </head>
194: <body bgcolor="#ccffdd">
195: <h1>$safeuser Construction Space</h1>
196: <h2>
197: The Learning<i>Online</i> Network with Computer-Assisted Personalized Approach
198: </h2>
199: <p>
200: This is your construction space within LON-CAPA, where you would construct resources which are meant to be
201: used across courses and institutions.
202: </p>
203: <p>
204: Material within this area can only be seen and edited by $safeuser and designated co-authors. To make
205: it available to students and other instructors, the material needs to be published.
206: </p>
207: </body>
208: </html>
209: END
210: close OUT;
211: }
212:
213: &System("/bin/chmod 02775 $fulldir");
214: &System("/bin/chmod 0775 $fulldir"."/index.html");
215:
216:
217: # Based on the authentiation mode, set the ownership of the directory.
218:
219: if($authentication eq "unix:") { # Unix mode authentication...
220: &System("/bin/chown -R $safeuser".":".$safeuser." ".$fulldir);
221: &JoinGroup($safeuser);
222: } else {
223: # Internal, Kerberos, and Local authentication are for users
224: # who do not have unix accounts on the system. Therefore we
225: # will give ownership of their public_html directories to www:www
226: # If the user is an internal auth user, the rest of the directory tree
227: # gets owned by root. This chown is needed in case what's really happening
228: # is that a file system user is being demoted to internal user...
229:
230: if($authentication eq "internal:") {
231: &System("/bin/chown -R root:root ".$homedir);
232: }
233: &System("/bin/chown -R www:www ".$fulldir);
234: }
235: &DisableRoot;
236:
237: exit 0;
238:
239: #----------------------------------------------------------------------
240: #
241: # Local utility procedures.
242: # These include:
243: # EnableRoot - Start running as root.
244: # DisableRoot- Stop running as root.
245: # JoinGroup - Join www to the specified group.
246:
247: # Turn on as root:
248:
249: sub EnableRoot {
250: if ($wwwid==$>) {
251: ($<,$>)=($>,$<);
252: ($(,$))=($),$();
253: }
254: else {
255: # root capability is already enabled
256: }
257: if($DEBUG) {
258: print("Enable Root - id = $> $<\n");
259: }
260: return $>;
261: }
262:
263: sub DisableRoot {
264: if ($wwwid==$<) {
265: ($<,$>)=($>,$<);
266: ($(,$))=($),$();
267: }
268: else {
269: # root capability is already disabled
270: }
271: if($DEBUG) {
272: print("Disable root: id = ".$>."\n");
273: }
274: }
275:
276: sub JoinGroup {
277: my $usergroup = shift;
278:
279: my $groups = `/usr/bin/groups www`;
280: # untaint
281: my ($safegroups)=($groups=~/:\s+([\s\w]+)/);
282: $groups=$safegroups;
283: chomp $groups; $groups=~s/^\S+\s+\:\s+//;
284: my @grouplist=split(/\s+/,$groups);
285: my @ugrouplist=grep {!/www|$usergroup/} @grouplist;
286: my $gl=join(',',(@ugrouplist,$usergroup));
287: if (&System('/usr/sbin/usermod','-G',$gl,'www')) {
288: if($DEBUG) {
289: print "Error. Could not make www a member of the group ".
290: "\"$usergroup\".\n";
291: }
292: exit 6;
293: }
294:
295: }
296:
297:
298:
299: sub System {
300: my ($command,@args) = @_;
301: if($DEBUG) {
302: print("system: $command with args ".join(' ',@args)."\n");
303: }
304: system($command,@args);
305: }
306:
307:
308:
309:
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