Annotation of loncom/lchtmldir, revision 1.17
1.7 albertel 1: #!/usr/bin/perl
1.1 foxr 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
1.17 ! foxr 44: #
1.1 foxr 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: #
1.17 ! foxr 64: #
1.1 foxr 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;
1.10 foxr 70: use Fcntl qw(:mode);
71: use DirHandle;
1.12 foxr 72: use POSIX;
1.1 foxr 73:
74: $ENV{'PATH'} = '/bin:/usr/bin:/usr/local/sbin:/home/httpd/perl';
75: delete @ENV{qw{IFS CDPATH ENV BASH_ENV}};
76:
1.12 foxr 77: my $DEBUG = 1; # .nonzero -> Debug printing enabled.
1.10 foxr 78: my $path_sep = "/"; # Unix like operating systems.
1.1 foxr 79:
80:
81: # If the UID of the running process is not www exit with error.
82:
83: if ($DEBUG) {
84: print("Checking uid...\n");
85: }
86: my $wwwid = getpwnam('www');
87: &DisableRoot;
88: if($wwwid != $>) {
89: if ($DEBUG) {
90: print("User ID incorrect. This program must be run as user 'www'\n");
91: }
92: exit 1; # Exit with error status.
93: }
94:
95: # There must be three 'command line' parameters. The first
96: # is the home directory of the user.
97: # The second is the name of the user. This is only referenced
98: # in code branches dealing with unix mode authentication.
99: # The last is the authentication mode which must be one of unix, internal
100: # krb4 or localauth.
101: # If there is an error in the argument count or countents, we exit with an
102: # error.
103:
104: if ($DEBUG) {
105: print("Checking parameters: \n");
106: }
107: if(@ARGV != 3) {
108: if($DEBUG) {
109: print("Error: lchtmldir need 3 parameters \n");
110: }
111: exit 2;
112: }
113: my ($dir,$username,$authentication) = @ARGV;
114:
115: if($DEBUG) {
116: print ("Directory = $dir \n");
117: print ("User = $username \n");
118: print ("Authmode = $authentication \n");
119:
120: }
121:
1.2 foxr 122: if( $authentication ne "unix:" &&
123: $authentication ne "internal:" &&
1.4 matthew 124: $authentication !~ /^krb(4|5):(.*)/ &&
1.2 foxr 125: $authentication ne "localauth:") {
1.1 foxr 126: if($DEBUG) {
127: print("Invalid authentication parameter: ".$authentication."\n");
128: print("Should be one of: unix, internal, krb4, localauth\n");
129: }
130: exit 3;
131: }
132:
133: # Untaint the username.
134:
135: my $match = $username =~ /^(\w+)$/;
136: my $patt = $1;
137:
138: if($DEBUG) {
139: print("Username word match flag = ".$match."\n");
140: print("Match value = ".$patt."\n");
141: }
142:
143: my $safeuser = $patt;
144: if($DEBUG) {
145: print("Save username = $safeuser \n");
146: }
1.16 albertel 147: if(($username ne $safeuser) or ($safeuser!~/^[A-z]/)) {
1.1 foxr 148: if($DEBUG) {
149: print("User name $username had illegal characters\n");
150: }
151: exit 4;
152: }
153:
154: #untaint the base directory require that the dir contain only
155: # alphas, / numbers or underscores, and end in /$safeuser
156:
157: $dir =~ /(^([\w\/]+))/;
158:
159: my $dirtry1 = $1;
160:
161: $dir =~ /$\/$safeuser/;
162: my $dirtry2 = $1;
163:
164: if(($dirtry1 ne $dir) or ($dirtry2 ne $dir)) {
165: if ($DEBUG) {
166: print("Directory $dir is not a valid home for $safeuser\n");
167: }
168: exit 5;
169: }
170:
171:
172: # As root, create the directory.
173:
1.9 foxr 174: my $homedir = $dirtry1;
175: my $fulldir = $homedir."/public_html";
176:
1.1 foxr 177: if($DEBUG) {
178: print("Full directory path is: $fulldir \n");
179: }
180: if(!( -e $dirtry1)) {
181: if($DEBUG) {
182: print("User's home directory $dirtry1 does not exist\n");
183: }
1.4 matthew 184: if ($authentication eq "unix:") {
185: exit 6;
186: }
1.1 foxr 187: }
1.16 albertel 188: if ($authentication eq "unix:") {
189: # check whether group $safeuser exists.
190: my $usergroups = `id -nG $safeuser`;
191: if (! grep /^$safeuser$/, split(/\s+/,$usergroups)) {
192: if($DEBUG) {
193: print("Group \"$safeuser\" does not exist or $safeuser is not a member of that group.\n");
194: }
195: exit 7;
196: }
197: }
198:
1.17 ! foxr 199:
! 200:
1.1 foxr 201: &EnableRoot;
202:
1.17 ! foxr 203: # If authentication is internal and the top level directory exists
! 204: # give it the right permissions (in case this is a modification.
! 205:
! 206: if ($authentication eq "internal:") {
! 207: chmod(0711, $homedir); # so www can enter ~/public_html.
! 208: }
! 209:
1.3 foxr 210: &System("/bin/mkdir -p $fulldir") unless (-e $fulldir);
1.1 foxr 211: unless(-e $fulldir."/index.html") {
212: open OUT,">".$fulldir."/index.html";
213: print OUT<<END;
214: <html>
215: <head>
216: <title>$safeuser</title>
217: </head>
1.5 www 218: <body bgcolor="#ccffdd">
219: <h1>$safeuser Construction Space</h1>
220: <h2>
221: The Learning<i>Online</i> Network with Computer-Assisted Personalized Approach
222: </h2>
1.1 foxr 223: <p>
1.5 www 224: This is your construction space within LON-CAPA, where you would construct resources which are meant to be
225: used across courses and institutions.
1.1 foxr 226: </p>
227: <p>
1.5 www 228: Material within this area can only be seen and edited by $safeuser and designated co-authors. To make
229: it available to students and other instructors, the material needs to be published.
1.1 foxr 230: </p>
231: </body>
232: </html>
233: END
234: close OUT;
235: }
1.9 foxr 236:
1.13 foxr 237: &System("/bin/chmod 02770 $fulldir");
238: &System("/bin/chmod 0770 $fulldir"."/index.html");
1.1 foxr 239:
240:
241: # Based on the authentiation mode, set the ownership of the directory.
242:
1.2 foxr 243: if($authentication eq "unix:") { # Unix mode authentication...
1.15 foxr 244: print "Unix auth\n";
1.14 foxr 245: &System("/bin/chown -R $safeuser:$safeuser"." ".$fulldir);
1.6 albertel 246: &JoinGroup($safeuser);
1.4 matthew 247: } else {
248: # Internal, Kerberos, and Local authentication are for users
249: # who do not have unix accounts on the system. Therefore we
250: # will give ownership of their public_html directories to www:www
1.9 foxr 251: # If the user is an internal auth user, the rest of the directory tree
252: # gets owned by root. This chown is needed in case what's really happening
253: # is that a file system user is being demoted to internal user...
254:
255: if($authentication eq "internal:") {
1.11 foxr 256: # In case the user was a unix/filesystem authenticated user,
257: # we'll take a bit of time here to write a script in the
258: # user's home directory that can reset ownerships and permissions
259: # back the way the used to be.
260:
1.12 foxr 261: # This can take long enough for lond to time out, so we'll do it
262: # in a separate process that we'll not wait for.
263: #
264: my $fpid = fork;
265: if($fpid) {
266: &DisableRoot;
267: exit 0;
268: } else {
269: print "Forked\n";
270: POSIX::setsid(); # Disassociate from parent.
271: print "Separate session\n";
272: &write_restore_script($homedir);
273: print "Restore script written\n";
274: &System("/bin/chown -R root:root ".$homedir);
275: &System("/bin/chown -R www:www ".$fulldir);
276: print "Exiting\n";
277: exit 0;
278: }
279: } else {
280: &System("/bin/chown -R www:www ".$fulldir);
281: }
1.11 foxr 282:
1.1 foxr 283: }
284: &DisableRoot;
285:
286: exit 0;
287:
288: #----------------------------------------------------------------------
289: #
290: # Local utility procedures.
291: # These include:
292: # EnableRoot - Start running as root.
293: # DisableRoot- Stop running as root.
294: # JoinGroup - Join www to the specified group.
295:
296: # Turn on as root:
297:
298: sub EnableRoot {
299: if ($wwwid==$>) {
300: ($<,$>)=($>,$<);
301: ($(,$))=($),$();
302: }
303: else {
304: # root capability is already enabled
305: }
306: if($DEBUG) {
1.4 matthew 307: print("Enable Root - id = $> $<\n");
1.1 foxr 308: }
309: return $>;
310: }
311:
312: sub DisableRoot {
313: if ($wwwid==$<) {
314: ($<,$>)=($>,$<);
315: ($(,$))=($),$();
316: }
317: else {
318: # root capability is already disabled
319: }
320: if($DEBUG) {
321: print("Disable root: id = ".$>."\n");
322: }
323: }
1.15 foxr 324: #
325: # Join the www user to the user's group.
326: # we must be running with euid as root at this time.
327: #
1.1 foxr 328: sub JoinGroup {
329: my $usergroup = shift;
330:
331: my $groups = `/usr/bin/groups www`;
1.6 albertel 332: # untaint
1.8 albertel 333: my ($safegroups)=($groups=~/:\s+([\s\w]+)/);
1.6 albertel 334: $groups=$safegroups;
1.1 foxr 335: chomp $groups; $groups=~s/^\S+\s+\:\s+//;
336: my @grouplist=split(/\s+/,$groups);
337: my @ugrouplist=grep {!/www|$usergroup/} @grouplist;
338: my $gl=join(',',(@ugrouplist,$usergroup));
339: if (&System('/usr/sbin/usermod','-G',$gl,'www')) {
340: if($DEBUG) {
341: print "Error. Could not make www a member of the group ".
342: "\"$usergroup\".\n";
343: }
344: exit 6;
345: }
1.15 foxr 346: if (-e '/var/run/httpd.pid') {
347: open(PID,'/var/run/httpd.pid');
348: my $pid=<PID>;
349: close(PID);
350: my ($safepid) = $pid=~ /(\d+)/;
351: $pid = $safepid;
352: if ($pid) {
353: my $status = system("kill -USR1 $safepid");
354: }
355: }
1.1 foxr 356: }
357:
358:
359:
360: sub System {
1.6 albertel 361: my ($command,@args) = @_;
1.1 foxr 362: if($DEBUG) {
1.6 albertel 363: print("system: $command with args ".join(' ',@args)."\n");
1.1 foxr 364: }
1.6 albertel 365: system($command,@args);
1.1 foxr 366: }
367:
368:
369:
370:
1.10 foxr 371:
372: #
373: # This file contains code to recursively process
374: # a Directory. This is a bit more powerful
375: # than File::Find in that we pass the full
376: # stat info to the processing function.
377: # For each file in the specified directory subtree,
378: # The user's Code reference is invoked for all files, regular and otherwise
379: # except:
380: # ., ..
381: #
382: # Parameters:
383: # code_ref - Code reference, invoked for each file in the tree.
384: # as follows: CodeRef(directory, name, statinfo)
385: # directory the path to the directory holding the file.
386: # name the name of the file within Directory.
387: # statinfo a reference to the stat of the file.
388: # start_dir - The starting point of the directory walk.
389: #
390: # NOTE:
391: # Yes, we could have just used File::Find, but since we have to get the
392: # stat anyway, this is actually simpler, as File::Find would have gotten
393: # the stat to figure out the file type and then we would have gotten it
394: # again.
395: #
396:
397: sub process_tree {
398: my ($code_ref, $start_dir) = @_;
399:
400: my $dir = new DirHandle $start_dir;
401: if (!defined($dir)) {
402: print "Failed to open dirhandle: $start_dir\n";
403: }
404:
405: # Now iterate through this level of the tree:
406:
407: while (defined (my $name = $dir->read)) {
408: next if $name =~/^\.\.?$/; # Skip ., .. (see cookbook pg 319)
409:
410: my $full_name = $start_dir.$path_sep.$name; # Full filename path.
411: my @stat_info = lstat($full_name);
412: my $mode = $stat_info[2];
413: my $type = $mode & 0170000; # File type.
414:
415: # Unless the file type is a symlink, call the user code:
416:
417: unless ($type == S_IFLNK) {
418: &$code_ref($start_dir, $name, \@stat_info);
419: }
420:
421: # If the entry is a directory, we need to recurse:
422:
423:
424: if (($type == S_IFDIR) != 0) {
425: &process_tree($code_ref, $full_name);
426: }
427: }
428:
429: }
430: #
1.11 foxr 431: # Callback from process_tree to write the script lines
432: # requried to restore files to current ownership and permission.
433: # Parameters:
434: # dir - Name of the directory the file lives in.
435: # name - Name of the file itself.
436: # statinfo - Array from lstat called on the file.
437: #
1.10 foxr 438: #
439: sub write_script {
440: my ($dir, $name, $statinfo) = @_;
441:
442: my $fullname = $dir.$path_sep.$name;
443:
444: # We're going to '' the name, but we need to deal with embedded
445: # ' characters. Using " is much worse as we'd then have to
446: # escape all the shell escapes too. This way all we need
447: # to do is replace ' with '\''
448:
449: $fullname =~ s/\'/\'\\\'\'/g;
450:
451: my $perms = $statinfo->[2] & 0777; # Just permissions.
452: printf CHMODSCRIPT "chmod 0%o '%s'\n", $perms, $fullname;
453: printf CHMODSCRIPT "chown %d:%d '%s'\n", $statinfo->[4], $statinfo->[5],
454: $fullname
455:
456:
457: }
1.11 foxr 458: #
459: # Write a script in the user's home directory that can restore
460: # the permissions and ownerhips of all the files in the directory
461: # tree to their current ownerships and permissions. This is done
462: # prior to making the user into an internally authenticated user
463: # in case they were previously file system authenticated and
464: # need to go back.
465: # The file we will create will be of the form
466: # restore_n.sh Where n is a number that we will keep
467: # incrementing as needed until there isn't a file by that name.
468: #
469: # Parameters:
470: # dir - Path to the user's home directory.
471: #
472: sub write_restore_script {
473: my ($dir) = @_;
474:
475: # Create a unique file:
476:
477: my $version_number = 0;
478: my $filename = 'restore_'.$version_number.'.sh';
479: my $full_name = $dir.$path_sep.$filename;
480:
481: while(-e $full_name) {
482: $version_number++;
483: $filename = 'restore_'.$version_number.'.sh';
484: $full_name = $dir.$path_sep.$filename;
485: }
486: # $full_name is the full path of a file that does not yet exist
487: # of the form we want:
488:
489: open(CHMODSCRIPT, "> $full_name");
490:
491: &process_tree(\&write_script, $dir);
492:
493: close(CHMODSCRIPT);
494:
495: chmod(0750, $full_name);
496:
497: }
1.10 foxr 498:
499:
500:
501:
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