Annotation of loncom/lchtmldir, revision 1.20
1.7 albertel 1: #!/usr/bin/perl
1.1 foxr 2:
3: # The Learning Online Network with CAPA
4: #
1.20 ! albertel 5: # $Id: lond,v 1.378 2007/08/08 22:24:36 albertel Exp $
! 6: #
1.1 foxr 7: # Copyright Michigan State University Board of Trustees
8: #
9: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
10: #
11: # LON-CAPA is free software; you can redistribute it and/or modify
12: # it under the terms of the GNU General Public License as published by
13: # the Free Software Foundation; either version 2 of the License, or
14: # (at your option) any later version.
15: #
16: # LON-CAPA is distributed in the hope that it will be useful,
17: # but WITHOUT ANY WARRANTY; without even the implied warranty of
18: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19: # GNU General Public License for more details.
20: #
21: # You should have received a copy of the GNU General Public License
22: # along with LON-CAPA; if not, write to the Free Software
23: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24: #
25: # /home/httpd/html/adm/gpl.txt
26: #
27: # http://www.lon-capa.org/
28: #
29: # lchtmldir - LONC-CAPA setuid script to:
30: # o If necessary, add a public_html directory
31: # to the specified user home directory.
32: # o Set the permissions according to the authentication type.
33: #
34: # Motivations:
35: # Originally, account creation would create a public_html
36: # directory for unix authorized people only. It is possible to have
37: # Kerberos, internal and locally authorized 'users' which may be authors
38: # and hence need a properly owned an protected public_html directory
39: # to serve as their construction space.
40: #
41: # Author:
42: # Ron Fox
43: # NSCL
44: # Michigan State University8
45: # East Lansing, MI 48824-1321
1.17 foxr 46: #
1.1 foxr 47: # General flow of control:
48: # 1. Validate process state (must be run as www).
49: # 2. Validate parameters: Need two parameters:
50: # o Homedir - Home diretory of user
51: # o Username - Name of the user.
52: # o AuthMode - Authentication mode, can be:
53: # - unix
54: # - internal
55: # - krb4
56: # - localauth
57: # 3. Untaint the usename and home directory
58: #
59: # 4. As root if necessary, create $Homedir/public_html
60: # 5. Set ownership/permissions according to authentication mode (AuthMode)
61: # - unix - ~owner:www/2775
62: # - krb4 - ~owner:www/2775
63: # - internal - www:www/2775
64: # - local - www:www/2775
65: #
1.17 foxr 66: #
1.1 foxr 67: #
68: # Take a few precautions to be sure that we're not vulnerable to trojan
69: # horses and other fine issues:
70: #
71: use strict;
1.10 foxr 72: use Fcntl qw(:mode);
73: use DirHandle;
1.12 foxr 74: use POSIX;
1.18 raeburn 75: use lib '/home/httpd/lib/perl/';
76: use LONCAPA qw(:match);
1.1 foxr 77:
78: $ENV{'PATH'} = '/bin:/usr/bin:/usr/local/sbin:/home/httpd/perl';
79: delete @ENV{qw{IFS CDPATH ENV BASH_ENV}};
80:
1.12 foxr 81: my $DEBUG = 1; # .nonzero -> Debug printing enabled.
1.10 foxr 82: my $path_sep = "/"; # Unix like operating systems.
1.1 foxr 83:
84:
85: # If the UID of the running process is not www exit with error.
86:
87: if ($DEBUG) {
88: print("Checking uid...\n");
89: }
90: my $wwwid = getpwnam('www');
91: &DisableRoot;
92: if($wwwid != $>) {
93: if ($DEBUG) {
94: print("User ID incorrect. This program must be run as user 'www'\n");
95: }
96: exit 1; # Exit with error status.
97: }
98:
99: # There must be three 'command line' parameters. The first
100: # is the home directory of the user.
101: # The second is the name of the user. This is only referenced
102: # in code branches dealing with unix mode authentication.
103: # The last is the authentication mode which must be one of unix, internal
104: # krb4 or localauth.
105: # If there is an error in the argument count or countents, we exit with an
106: # error.
107:
108: if ($DEBUG) {
109: print("Checking parameters: \n");
110: }
111: if(@ARGV != 3) {
112: if($DEBUG) {
113: print("Error: lchtmldir need 3 parameters \n");
114: }
115: exit 2;
116: }
117: my ($dir,$username,$authentication) = @ARGV;
118:
119: if($DEBUG) {
120: print ("Directory = $dir \n");
121: print ("User = $username \n");
122: print ("Authmode = $authentication \n");
123:
124: }
125:
1.2 foxr 126: if( $authentication ne "unix:" &&
127: $authentication ne "internal:" &&
1.4 matthew 128: $authentication !~ /^krb(4|5):(.*)/ &&
1.2 foxr 129: $authentication ne "localauth:") {
1.1 foxr 130: if($DEBUG) {
131: print("Invalid authentication parameter: ".$authentication."\n");
132: print("Should be one of: unix, internal, krb4, localauth\n");
133: }
134: exit 3;
135: }
136:
137: # Untaint the username.
138:
1.18 raeburn 139: my $match = $username =~ /^($match_username)$/;
1.1 foxr 140: my $patt = $1;
141:
142: if($DEBUG) {
143: print("Username word match flag = ".$match."\n");
144: print("Match value = ".$patt."\n");
145: }
146:
147: my $safeuser = $patt;
148: if($DEBUG) {
149: print("Save username = $safeuser \n");
150: }
1.18 raeburn 151: if($username ne $safeuser) {
1.1 foxr 152: if($DEBUG) {
153: print("User name $username had illegal characters\n");
154: }
155: exit 4;
156: }
157:
158: #untaint the base directory require that the dir contain only
159: # alphas, / numbers or underscores, and end in /$safeuser
160:
161:
162:
1.19 albertel 163: my ($allowed_dir) = ($dir =~ m{(^([/]|$match_username)+)});
1.1 foxr 164:
1.19 albertel 165: my $has_correct_end = ($dir =~ m{/\Q$safeuser\E$});
166:
167: if(($allowed_dir ne $dir) or (!$has_correct_end)) {
1.1 foxr 168: if ($DEBUG) {
169: print("Directory $dir is not a valid home for $safeuser\n");
170: }
171: exit 5;
172: }
173:
174: # As root, create the directory.
175:
1.19 albertel 176: my $homedir = $allowed_dir;
1.9 foxr 177: my $fulldir = $homedir."/public_html";
178:
1.1 foxr 179: if($DEBUG) {
180: print("Full directory path is: $fulldir \n");
181: }
1.19 albertel 182: if(!( -e $homedir)) {
1.1 foxr 183: if($DEBUG) {
1.19 albertel 184: print("User's home directory $homedir does not exist\n");
1.1 foxr 185: }
1.4 matthew 186: if ($authentication eq "unix:") {
187: exit 6;
188: }
1.1 foxr 189: }
1.16 albertel 190: if ($authentication eq "unix:") {
191: # check whether group $safeuser exists.
192: my $usergroups = `id -nG $safeuser`;
193: if (! grep /^$safeuser$/, split(/\s+/,$usergroups)) {
194: if($DEBUG) {
195: print("Group \"$safeuser\" does not exist or $safeuser is not a member of that group.\n");
196: }
197: exit 7;
198: }
199: }
200:
1.17 foxr 201:
202:
1.1 foxr 203: &EnableRoot;
204:
1.17 foxr 205: # If authentication is internal and the top level directory exists
206: # give it the right permissions (in case this is a modification.
207:
208: if ($authentication eq "internal:") {
209: chmod(0711, $homedir); # so www can enter ~/public_html.
210: }
211:
1.3 foxr 212: &System("/bin/mkdir -p $fulldir") unless (-e $fulldir);
1.1 foxr 213: unless(-e $fulldir."/index.html") {
214: open OUT,">".$fulldir."/index.html";
215: print OUT<<END;
216: <html>
217: <head>
218: <title>$safeuser</title>
219: </head>
1.5 www 220: <body bgcolor="#ccffdd">
221: <h1>$safeuser Construction Space</h1>
222: <h2>
223: The Learning<i>Online</i> Network with Computer-Assisted Personalized Approach
224: </h2>
1.1 foxr 225: <p>
1.5 www 226: This is your construction space within LON-CAPA, where you would construct resources which are meant to be
227: used across courses and institutions.
1.1 foxr 228: </p>
229: <p>
1.5 www 230: Material within this area can only be seen and edited by $safeuser and designated co-authors. To make
231: it available to students and other instructors, the material needs to be published.
1.1 foxr 232: </p>
233: </body>
234: </html>
235: END
236: close OUT;
237: }
1.9 foxr 238:
1.13 foxr 239: &System("/bin/chmod 02770 $fulldir");
240: &System("/bin/chmod 0770 $fulldir"."/index.html");
1.1 foxr 241:
242:
243: # Based on the authentiation mode, set the ownership of the directory.
244:
1.2 foxr 245: if($authentication eq "unix:") { # Unix mode authentication...
1.15 foxr 246: print "Unix auth\n";
1.14 foxr 247: &System("/bin/chown -R $safeuser:$safeuser"." ".$fulldir);
1.6 albertel 248: &JoinGroup($safeuser);
1.4 matthew 249: } else {
250: # Internal, Kerberos, and Local authentication are for users
251: # who do not have unix accounts on the system. Therefore we
252: # will give ownership of their public_html directories to www:www
1.9 foxr 253: # If the user is an internal auth user, the rest of the directory tree
254: # gets owned by root. This chown is needed in case what's really happening
255: # is that a file system user is being demoted to internal user...
256:
257: if($authentication eq "internal:") {
1.11 foxr 258: # In case the user was a unix/filesystem authenticated user,
259: # we'll take a bit of time here to write a script in the
260: # user's home directory that can reset ownerships and permissions
261: # back the way the used to be.
262:
1.12 foxr 263: # This can take long enough for lond to time out, so we'll do it
264: # in a separate process that we'll not wait for.
265: #
266: my $fpid = fork;
267: if($fpid) {
268: &DisableRoot;
269: exit 0;
270: } else {
271: print "Forked\n";
272: POSIX::setsid(); # Disassociate from parent.
273: print "Separate session\n";
274: &write_restore_script($homedir);
275: print "Restore script written\n";
276: &System("/bin/chown -R root:root ".$homedir);
277: &System("/bin/chown -R www:www ".$fulldir);
278: print "Exiting\n";
279: exit 0;
280: }
281: } else {
282: &System("/bin/chown -R www:www ".$fulldir);
283: }
1.11 foxr 284:
1.1 foxr 285: }
286: &DisableRoot;
287:
288: exit 0;
289:
290: #----------------------------------------------------------------------
291: #
292: # Local utility procedures.
293: # These include:
294: # EnableRoot - Start running as root.
295: # DisableRoot- Stop running as root.
296: # JoinGroup - Join www to the specified group.
297:
298: # Turn on as root:
299:
300: sub EnableRoot {
301: if ($wwwid==$>) {
302: ($<,$>)=($>,$<);
303: ($(,$))=($),$();
304: }
305: else {
306: # root capability is already enabled
307: }
308: if($DEBUG) {
1.4 matthew 309: print("Enable Root - id = $> $<\n");
1.1 foxr 310: }
311: return $>;
312: }
313:
314: sub DisableRoot {
315: if ($wwwid==$<) {
316: ($<,$>)=($>,$<);
317: ($(,$))=($),$();
318: }
319: else {
320: # root capability is already disabled
321: }
322: if($DEBUG) {
323: print("Disable root: id = ".$>."\n");
324: }
325: }
1.15 foxr 326: #
327: # Join the www user to the user's group.
328: # we must be running with euid as root at this time.
329: #
1.1 foxr 330: sub JoinGroup {
331: my $usergroup = shift;
332:
333: my $groups = `/usr/bin/groups www`;
1.6 albertel 334: # untaint
1.8 albertel 335: my ($safegroups)=($groups=~/:\s+([\s\w]+)/);
1.6 albertel 336: $groups=$safegroups;
1.1 foxr 337: chomp $groups; $groups=~s/^\S+\s+\:\s+//;
338: my @grouplist=split(/\s+/,$groups);
339: my @ugrouplist=grep {!/www|$usergroup/} @grouplist;
340: my $gl=join(',',(@ugrouplist,$usergroup));
341: if (&System('/usr/sbin/usermod','-G',$gl,'www')) {
342: if($DEBUG) {
343: print "Error. Could not make www a member of the group ".
344: "\"$usergroup\".\n";
345: }
346: exit 6;
347: }
1.15 foxr 348: if (-e '/var/run/httpd.pid') {
349: open(PID,'/var/run/httpd.pid');
350: my $pid=<PID>;
351: close(PID);
352: my ($safepid) = $pid=~ /(\d+)/;
353: $pid = $safepid;
354: if ($pid) {
355: my $status = system("kill -USR1 $safepid");
356: }
357: }
1.1 foxr 358: }
359:
360:
361:
362: sub System {
1.6 albertel 363: my ($command,@args) = @_;
1.1 foxr 364: if($DEBUG) {
1.6 albertel 365: print("system: $command with args ".join(' ',@args)."\n");
1.1 foxr 366: }
1.6 albertel 367: system($command,@args);
1.1 foxr 368: }
369:
370:
371:
372:
1.10 foxr 373:
374: #
375: # This file contains code to recursively process
376: # a Directory. This is a bit more powerful
377: # than File::Find in that we pass the full
378: # stat info to the processing function.
379: # For each file in the specified directory subtree,
380: # The user's Code reference is invoked for all files, regular and otherwise
381: # except:
382: # ., ..
383: #
384: # Parameters:
385: # code_ref - Code reference, invoked for each file in the tree.
386: # as follows: CodeRef(directory, name, statinfo)
387: # directory the path to the directory holding the file.
388: # name the name of the file within Directory.
389: # statinfo a reference to the stat of the file.
390: # start_dir - The starting point of the directory walk.
391: #
392: # NOTE:
393: # Yes, we could have just used File::Find, but since we have to get the
394: # stat anyway, this is actually simpler, as File::Find would have gotten
395: # the stat to figure out the file type and then we would have gotten it
396: # again.
397: #
398:
399: sub process_tree {
400: my ($code_ref, $start_dir) = @_;
401:
402: my $dir = new DirHandle $start_dir;
403: if (!defined($dir)) {
404: print "Failed to open dirhandle: $start_dir\n";
405: }
406:
407: # Now iterate through this level of the tree:
408:
409: while (defined (my $name = $dir->read)) {
410: next if $name =~/^\.\.?$/; # Skip ., .. (see cookbook pg 319)
411:
412: my $full_name = $start_dir.$path_sep.$name; # Full filename path.
413: my @stat_info = lstat($full_name);
414: my $mode = $stat_info[2];
415: my $type = $mode & 0170000; # File type.
416:
417: # Unless the file type is a symlink, call the user code:
418:
419: unless ($type == S_IFLNK) {
420: &$code_ref($start_dir, $name, \@stat_info);
421: }
422:
423: # If the entry is a directory, we need to recurse:
424:
425:
426: if (($type == S_IFDIR) != 0) {
427: &process_tree($code_ref, $full_name);
428: }
429: }
430:
431: }
432: #
1.11 foxr 433: # Callback from process_tree to write the script lines
434: # requried to restore files to current ownership and permission.
435: # Parameters:
436: # dir - Name of the directory the file lives in.
437: # name - Name of the file itself.
438: # statinfo - Array from lstat called on the file.
439: #
1.10 foxr 440: #
441: sub write_script {
442: my ($dir, $name, $statinfo) = @_;
443:
444: my $fullname = $dir.$path_sep.$name;
445:
446: # We're going to '' the name, but we need to deal with embedded
447: # ' characters. Using " is much worse as we'd then have to
448: # escape all the shell escapes too. This way all we need
449: # to do is replace ' with '\''
450:
451: $fullname =~ s/\'/\'\\\'\'/g;
452:
453: my $perms = $statinfo->[2] & 0777; # Just permissions.
454: printf CHMODSCRIPT "chmod 0%o '%s'\n", $perms, $fullname;
455: printf CHMODSCRIPT "chown %d:%d '%s'\n", $statinfo->[4], $statinfo->[5],
456: $fullname
457:
458:
459: }
1.11 foxr 460: #
461: # Write a script in the user's home directory that can restore
462: # the permissions and ownerhips of all the files in the directory
463: # tree to their current ownerships and permissions. This is done
464: # prior to making the user into an internally authenticated user
465: # in case they were previously file system authenticated and
466: # need to go back.
467: # The file we will create will be of the form
468: # restore_n.sh Where n is a number that we will keep
469: # incrementing as needed until there isn't a file by that name.
470: #
471: # Parameters:
472: # dir - Path to the user's home directory.
473: #
474: sub write_restore_script {
475: my ($dir) = @_;
476:
477: # Create a unique file:
478:
479: my $version_number = 0;
480: my $filename = 'restore_'.$version_number.'.sh';
481: my $full_name = $dir.$path_sep.$filename;
482:
483: while(-e $full_name) {
484: $version_number++;
485: $filename = 'restore_'.$version_number.'.sh';
486: $full_name = $dir.$path_sep.$filename;
487: }
488: # $full_name is the full path of a file that does not yet exist
489: # of the form we want:
490:
491: open(CHMODSCRIPT, "> $full_name");
492:
493: &process_tree(\&write_script, $dir);
494:
495: close(CHMODSCRIPT);
496:
497: chmod(0750, $full_name);
498:
499: }
1.10 foxr 500:
501:
502:
503:
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