Annotation of loncom/lcuseradd, revision 1.39
1.1 harris41 1: #!/usr/bin/perl
1.16 harris41 2:
3: # The Learning Online Network with CAPA
1.1 harris41 4: #
1.16 harris41 5: # lcuseradd - LON-CAPA setuid script to coordinate all actions
6: # with adding a user with filesystem privileges (e.g. author)
1.1 harris41 7: #
1.16 harris41 8: #
1.39 ! albertel 9: # $Id: lcuseradd,v 1.38 2005/07/29 17:33:18 raeburn Exp $
1.16 harris41 10: ###
1.15 harris41 11:
12: ###############################################################################
13: ## ##
14: ## ORGANIZATION OF THIS PERL SCRIPT ##
15: ## ##
16: ## 1. Description of script ##
17: ## 2. Invoking script (standard input) ##
18: ## 3. Example usage inside another piece of code ##
19: ## 4. Description of functions ##
20: ## 5. Exit codes ##
21: ## 6. Initializations ##
22: ## 7. Make sure this process is running from user=www ##
23: ## 8. Start running script with www permissions ##
24: ## 9. Handle case of another lcpasswd process (locking) ##
25: ## 10. Error-check input, need 3 values (user name, password 1, password 2) ##
26: ## 11. Start running script with root permissions ##
27: ## 12. Add user and make www a member of the user-specific group ##
28: ## 13. Set password ##
29: ## 14. Make final modifications to the user directory ##
30: ## 15. Exit script (unlock) ##
31: ## ##
32: ###############################################################################
1.1 harris41 33:
34: use strict;
1.35 foxr 35: use File::Find;
36:
1.1 harris41 37:
1.15 harris41 38: # ------------------------------------------------------- Description of script
39: #
1.1 harris41 40: # This script is a setuid script that should
1.20 foxr 41: # be run by user 'www'. It creates a /home/USERNAME directory.
1.15 harris41 42: # It adds a user to the unix system.
1.2 harris41 43: # Passwords are set with lcpasswd.
44: # www becomes a member of this user group.
1.1 harris41 45:
1.15 harris41 46: # -------------- Invoking script (standard input versus command-line arguments)
1.26 foxr 47: # Otherwise sensitive information will be available to ps-ers for
48: # a small but exploitable time window.
1.15 harris41 49: #
50: # Standard input (STDIN) usage
1.1 harris41 51: # First line is USERNAME
52: # Second line is PASSWORD
1.3 harris41 53: # Third line is PASSWORD
1.26 foxr 54: # Fouth line is the name of a file to which an error code will be written.
55: # If the fourth line is omitted, no error file will be written.
56: # In either case, the program Exits with the code as its Exit status.
57: # The error file will just be a single line containing an
58: # error code.
59: #
60: #
1.15 harris41 61: #
62: # Command-line arguments [USERNAME] [PASSWORD] [PASSWORD]
63: # Yes, but be very careful here (don't pass shell commands)
64: # and this is only supported to allow perl-system calls.
65: #
1.7 harris41 66: # Valid passwords must consist of the
67: # ascii characters within the inclusive
68: # range of 0x20 (32) to 0x7E (126).
69: # These characters are:
70: # SPACE and
71: # !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
72: # PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
1.15 harris41 73: #
1.7 harris41 74: # Valid user names must consist of ascii
75: # characters that are alphabetical characters
76: # (A-Z,a-z), numeric (0-9), or the underscore
77: # mark (_). (Essentially, the perl regex \w).
1.15 harris41 78: # User names must begin with an alphabetical character
79: # (A-Z,a-z).
1.7 harris41 80:
1.15 harris41 81: # ---------------------------------- Example usage inside another piece of code
1.4 harris41 82: # Usage within code
83: #
1.26 foxr 84: # $Exitcode=
1.15 harris41 85: # system("/home/httpd/perl/lcuseradd","NAME","PASSWORD1","PASSWORD2")/256;
1.26 foxr 86: # print "uh-oh" if $Exitcode;
1.4 harris41 87:
1.15 harris41 88: # ---------------------------------------------------- Description of functions
89: # enable_root_capability() : have setuid script run as root
90: # disable_root_capability() : have setuid script run as www
91: # try_to_lock() : make sure that another lcpasswd process isn't running
92:
93: # ------------------------------------------------------------------ Exit codes
1.26 foxr 94: # These are the Exit codes.
1.13 harris41 95: # ( (0,"ok"),
96: # (1,"User ID mismatch. This program must be run as user 'www'"),
1.15 harris41 97: # (2,"Error. This program needs 3 command-line arguments (username, ".
98: # "password 1, password 2)."),
1.13 harris41 99: # (3,"Error. Three lines should be entered into standard input."),
1.15 harris41 100: # (4,"Error. Too many other simultaneous password change requests being ".
101: # "made."),
1.13 harris41 102: # (5,"Error. User $username does not exist."),
103: # (6,"Error. Could not make www a member of the group \"$safeusername\"."),
104: # (7,"Error. Root was not successfully enabled.),
1.15 harris41 105: # (8,"Error. Cannot set password."),
1.13 harris41 106: # (9,"Error. The user name specified has invalid characters."),
107: # (10,"Error. A password entry had an invalid character."),
108: # (11,"Error. User already exists.),
1.15 harris41 109: # (12,"Error. Something went wrong with the addition of user ".
110: # "\"$safeusername\"."),
1.13 harris41 111: # (13,"Error. Password mismatch."),
1.38 raeburn 112: # (14, "Error filename is invalid"),
113: # (15, "Error. Could not add home directory.")
1.4 harris41 114:
1.15 harris41 115: # ------------------------------------------------------------- Initializations
1.1 harris41 116: # Security
1.15 harris41 117: $ENV{'PATH'}='/bin/:/usr/bin:/usr/local/sbin:/home/httpd/perl'; # Nullify path
118: # information
1.16 harris41 119: delete @ENV{qw(IFS CDPATH ENV BASH_ENV)}; # nullify potential taints
1.2 harris41 120:
1.15 harris41 121: # Do not print error messages.
122: my $noprint=1;
123:
1.23 foxr 124: print "In lcuseradd\n" unless $noprint;
125:
1.15 harris41 126: # ----------------------------- Make sure this process is running from user=www
127: my $wwwid=getpwnam('www');
128: &disable_root_capability;
129: if ($wwwid!=$>) {
130: print("User ID mismatch. This program must be run as user 'www'\n")
131: unless $noprint;
1.26 foxr 132: &Exit(1);
1.4 harris41 133: }
1.15 harris41 134:
135: # ----------------------------------- Start running script with www permissions
1.4 harris41 136: &disable_root_capability;
137:
1.15 harris41 138: # --------------------------- Handle case of another lcpasswd process (locking)
1.4 harris41 139: unless (&try_to_lock("/tmp/lock_lcpasswd")) {
1.15 harris41 140: print "Error. Too many other simultaneous password change requests being ".
141: "made.\n" unless $noprint;
1.26 foxr 142: &Exit(4);
1.4 harris41 143: }
144:
1.15 harris41 145: # ------- Error-check input, need 3 values (user name, password 1, password 2).
1.4 harris41 146: my @input;
1.26 foxr 147: if (@ARGV>=3) {
1.4 harris41 148: @input=@ARGV;
1.28 foxr 149: } elsif (@ARGV) {
1.26 foxr 150: print("Error. This program needs at least 3 command-line arguments (username, ".
151: "password 1, password 2 [errorfile]).\n") unless $noprint;
1.4 harris41 152: unlink('/tmp/lock_lcpasswd');
1.26 foxr 153: &Exit(2);
1.28 foxr 154: } else {
1.4 harris41 155: @input=<>;
1.26 foxr 156: if (@input < 3) {
157: print("Error. At least three lines should be entered into standard input.\n")
1.15 harris41 158: unless $noprint;
1.4 harris41 159: unlink('/tmp/lock_lcpasswd');
1.26 foxr 160: &Exit(3);
1.4 harris41 161: }
1.19 harris41 162: foreach (@input) {chomp;}
1.4 harris41 163: }
164:
1.26 foxr 165: my ($username,$password1,$password2, $error_file)=@input;
1.23 foxr 166: print "Username = ".$username."\n" unless $noprint;
1.4 harris41 167: $username=~/^(\w+)$/;
1.22 foxr 168: print "Username after substitution - ".$username unless $noprint;
1.4 harris41 169: my $safeusername=$1;
1.23 foxr 170: print "Safe username = $safeusername \n" unless $noprint;
1.22 foxr 171:
1.15 harris41 172: if (($username ne $safeusername) or ($safeusername!~/^[A-Za-z]/)) {
1.22 foxr 173: print "Error. The user name specified $username $safeusername has invalid characters.\n"
1.15 harris41 174: unless $noprint;
1.8 harris41 175: unlink('/tmp/lock_lcpasswd');
1.26 foxr 176: &Exit(9);
1.8 harris41 177: }
178: my $pbad=0;
1.19 harris41 179: foreach (split(//,$password1)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}}
180: foreach (split(//,$password2)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}}
1.8 harris41 181: if ($pbad) {
1.26 foxr 182: print "Error. A password entry had an invalid character.\n" unless $noprint;
1.8 harris41 183: unlink('/tmp/lock_lcpasswd');
1.26 foxr 184: &Exit(10);
1.8 harris41 185: }
1.5 harris41 186:
1.26 foxr 187: #
188: # Safe the filename. For our case, it must only have alpha, numeric, period
189: # and path sparators..
190: #
191:
192: print "Error file is $error_file \n" unless $noprint;
193:
194: if($error_file) {
195: if($error_file =~ /^([(\w)(\d)\.\/]+)$/) {
196: print "Error file matched pattern $error_file : $1\n" unless $noprint;
197: my $safe_error_file = $1; # Untainted I think.
198: print "Error file after transform $safe_error_file\n"
199: unless $noprint;
200: if($error_file == $safe_error_file) {
201: $error_file = $safe_error_file; # untainted error_file.
202: } else {
203: $error_file ="";
204: print "Invalid error filename\n" unless $noprint;
205: Exit(14);
206: }
207:
1.28 foxr 208: } else {
1.26 foxr 209: $error_file="";
210: print "Invalid error filename\n" unless $noprint;
211: Exit(14);
212: }
213: }
214:
215:
1.31 foxr 216: # -- Only add the user if they are >not< in /etc/passwd.
217: # Used to look for the ability to create a new directory for the
218: # user, however that disallows authentication changes from i
219: # internal->fs.. so just check the passwd file instead.
220: #
1.34 foxr 221: my $not_found = system("cut -d: -f1 /etc/passwd | grep -q \"^$safeusername\$\" ");
1.31 foxr 222: if (!$not_found) {
223: print "Error user already exists\n" unless $noprint;
1.7 harris41 224: unlink('/tmp/lock_lcpasswd');
1.26 foxr 225: &Exit(11);
1.7 harris41 226: }
227:
1.31 foxr 228:
229:
1.15 harris41 230: # -- Only add user if the two password arguments match.
1.23 foxr 231:
1.5 harris41 232: if ($password1 ne $password2) {
1.6 harris41 233: print "Error. Password mismatch.\n" unless $noprint;
1.5 harris41 234: unlink('/tmp/lock_lcpasswd');
1.26 foxr 235: &Exit(13);
1.5 harris41 236: }
1.23 foxr 237: print "enabling root\n" unless $noprint;
1.15 harris41 238: # ---------------------------------- Start running script with root permissions
1.4 harris41 239: &enable_root_capability;
240:
1.38 raeburn 241: # ------------------- Add group and user, and make www a member of the group
242: # -- Add group
243:
244: print "adding group: $safeusername \n" unless $noprint;
245: my $status = system('/usr/sbin/groupadd', $safeusername);
246: if ($status) {
247: print "Error. Something went wrong with the addition of group ".
248: "\"$safeusername\".\n" unless $noprint;
249: print "Final status of groupadd = $status\n";
250: unlink('/tmp/lock_lcpasswd');
251: &Exit(12);
252: }
253: my $gid = getgrnam($safeusername);
254:
1.15 harris41 255: # -- Add user
1.23 foxr 256:
257: print "adding user: $safeusername \n" unless $noprint;
1.38 raeburn 258: my $status = system('/usr/sbin/useradd','-c','LON-CAPA user','-g',$gid,$safeusername);
1.23 foxr 259: if ($status) {
1.15 harris41 260: print "Error. Something went wrong with the addition of user ".
261: "\"$safeusername\".\n" unless $noprint;
1.38 raeburn 262: system("/usr/sbin/groupdel $safeusername");
1.37 foxr 263: print "Final status of useradd = $status\n";
1.4 harris41 264: unlink('/tmp/lock_lcpasswd');
1.26 foxr 265: &Exit(12);
1.4 harris41 266: }
1.36 albertel 267:
1.23 foxr 268: print "Done adding user\n" unless $noprint;
1.7 harris41 269: # Make www a member of that user group.
1.26 foxr 270: my $groups=`/usr/bin/groups www` or &Exit(6);
1.27 albertel 271: # untaint
1.29 albertel 272: my ($safegroups)=($groups=~/:\s*([\s\w]+)/);
1.27 albertel 273: $groups=$safegroups;
1.17 harris41 274: chomp $groups; $groups=~s/^\S+\s+\:\s+//;
275: my @grouplist=split(/\s+/,$groups);
276: my @ugrouplist=grep {!/www|$safeusername/} @grouplist;
277: my $gl=join(',',(@ugrouplist,$safeusername));
1.38 raeburn 278: print "Putting www in user's group\n" unless $noprint;
1.17 harris41 279: if (system('/usr/sbin/usermod','-G',$gl,'www')) {
1.15 harris41 280: print "Error. Could not make www a member of the group ".
281: "\"$safeusername\".\n" unless $noprint;
1.5 harris41 282: unlink('/tmp/lock_lcpasswd');
1.26 foxr 283: &Exit(6);
1.5 harris41 284: }
285:
1.15 harris41 286: # ---------------------------------------------------------------- Set password
287: # Set password with lcpasswd (which creates smbpasswd entry).
1.2 harris41 288:
1.15 harris41 289: unlink('/tmp/lock_lcpasswd');
290: &disable_root_capability;
1.16 harris41 291: ($>,$<)=($wwwid,$wwwid);
1.23 foxr 292: print "Opening lcpasswd pipeline\n" unless $noprint;
1.16 harris41 293: open OUT,"|/home/httpd/perl/lcpasswd";
1.15 harris41 294: print OUT $safeusername;
295: print OUT "\n";
296: print OUT $password1;
297: print OUT "\n";
298: print OUT $password1;
299: print OUT "\n";
300: close OUT;
301: if ($?) {
1.26 foxr 302: print "abnormal Exit from close lcpasswd\n" unless $noprint;
303: &Exit(8);
1.8 harris41 304: }
1.18 harris41 305: ($>,$<)=($wwwid,0);
1.15 harris41 306: &enable_root_capability;
1.8 harris41 307:
1.38 raeburn 308: # Check if home directory exists for user
309: # If not, create one.
310: if (!-e "/home/$safeusername") {
311: if (!mkdir("/home/$safeusername",0710)) {
312: print "Error. Could not add home directory for ".
313: "\"$safeusername\".\n" unless $noprint;
314: unlink('/tmp/lock_lcpasswd');
315: &Exit(15);
316: }
317: }
1.20 foxr 318:
1.15 harris41 319: # ------------------------------ Make final modifications to the user directory
320: # -- Add a public_html file with a stand-in index.html file
1.8 harris41 321:
1.38 raeburn 322: if (-d "/home/$safeusername") {
323: system('/bin/chmod','-R','0660',"/home/$safeusername");
324: system('/bin/chmod','0710',"/home/$safeusername");
325: mkdir "/home/$safeusername/public_html",0755;
326: open OUT,">/home/$safeusername/public_html/index.html";
327: print OUT<<END;
1.21 foxr 328: <html>
329: <head>
330: <title>$safeusername</title>
331: </head>
332: <body>
1.24 www 333: <h1>Construction Space</h1>
334: <h3>$safeusername</h3>
1.21 foxr 335: </body>
336: </html>
337: END
338: close OUT;
1.38 raeburn 339: }
1.35 foxr 340:
1.32 foxr 341: #
342: # In order to allow the loncapa daemons appropriate access
343: # to public_html, Top level and public_html directories should
1.34 foxr 344: # be owned by safeusername:safeusername as should the smaple index.html..
1.24 www 345: print "lcuseradd ownership\n" unless $noprint;
1.32 foxr 346: system('/bin/chown','-R',"$safeusername:$safeusername","/home/$safeusername"); # First set std ownership on everything.
1.35 foxr 347: &set_public_html_permissions("/home/$safeusername/public_html");
1.33 foxr 348: # system('/bin/chown',"$safeusername:www","/home/$safeusername"); # Now adust top level...
349: # system('/bin/chown','-R',"$safeusername:www","/home/$safeusername/public_html"); # And web dir.
1.24 www 350: # ---------------------------------------------------- Gracefull Apache Restart
351: if (-e '/var/run/httpd.pid') {
352: print "lcuseradd Apache restart\n" unless $noprint;
353: open(PID,'/var/run/httpd.pid');
354: my $pid=<PID>;
355: close(PID);
1.39 ! albertel 356: $pid=~ /(\D+)/;
1.35 foxr 357: my $safepid = $1;
1.24 www 358: if ($pid) {
1.27 albertel 359: system('kill','-USR1',"$safepid");
1.24 www 360: }
361: }
1.15 harris41 362: # -------------------------------------------------------- Exit script
1.26 foxr 363: print "lcuseradd Exiting\n" unless $noprint;
1.8 harris41 364: &disable_root_capability;
1.26 foxr 365: &Exit(0);
1.1 harris41 366:
1.15 harris41 367: # ---------------------------------------------- Have setuid script run as root
1.5 harris41 368: sub enable_root_capability {
369: if ($wwwid==$>) {
1.23 foxr 370: ($<,$>)=($>,0);
371: ($(,$))=($),0);
1.28 foxr 372: } else {
1.5 harris41 373: # root capability is already enabled
374: }
375: return $>;
376: }
377:
1.15 harris41 378: # ----------------------------------------------- Have setuid script run as www
1.5 harris41 379: sub disable_root_capability {
380: if ($wwwid==$<) {
381: ($<,$>)=($>,$<);
382: ($(,$))=($),$();
1.28 foxr 383: } else {
1.5 harris41 384: # root capability is already disabled
385: }
386: }
387:
1.15 harris41 388: # ----------------------- Make sure that another lcpasswd process isn't running
1.5 harris41 389: sub try_to_lock {
390: my ($lockfile)=@_;
391: my $currentpid;
392: my $lastpid;
393: # Do not manipulate lock file as root
394: if ($>==0) {
395: return 0;
396: }
397: # Try to generate lock file.
398: # Wait 3 seconds. If same process id is in
399: # lock file, then assume lock file is stale, and
400: # go ahead. If process id's fluctuate, try
401: # for a maximum of 10 times.
402: for (0..10) {
403: if (-e $lockfile) {
404: open(LOCK,"<$lockfile");
405: $currentpid=<LOCK>;
406: close LOCK;
407: if ($currentpid==$lastpid) {
408: last;
409: }
410: sleep 3;
411: $lastpid=$currentpid;
1.28 foxr 412: } else {
1.5 harris41 413: last;
414: }
415: if ($_==10) {
416: return 0;
417: }
418: }
419: open(LOCK,">$lockfile");
420: print LOCK $$;
421: close LOCK;
422: return 1;
423: }
1.35 foxr 424: # Called by File::Find::find for each file examined.
425: #
426: # Untaint the file and, if it is a directory,
427: # chmod it to 02770
428: #
429: sub set_permission {
430: $File::Find::name =~ /^(.*)$/;
431: my $safe_name = $1; # Untainted filename...
432:
433: print "$safe_name" unless $noprint;
434: if(-d $safe_name) {
435: print " - directory" unless $noprint;
436: chmod(02770, $safe_name);
437: }
438: print "\n" unless $noprint;
439:
440: }
441: #
442: # Set up the correct permissions for all files in the
443: # user's public htmldir. We just do a chmod -R 0660 ... for
444: # the ordinary files. The we use File::Find
445: # to pop through the directory tree changing directories only
446: # to 02770:
447: #
448: sub set_public_html_permissions {
449: my ($topdir) = @_;
450:
451: # Set the top level dir permissions (I'm not sure if find
452: # will enumerate it specifically), correctly and all
453: # files and dirs to the 'ordinary' file permissions:
454:
455: system("chmod -R 0660 $topdir");
456: chmod(02770, $topdir);
457:
458: # Now use find to locate all directories under $topdir
459: # and set their modes to 02770...
460: #
461: print "Find file\n " unless $noprint;
462: File::Find::find({"untaint" => 1,
463: "untaint_pattern" => qr(/^(.*)$/),
464: "untaint_skip" => 1,
465: "no_chdir" => 1,
466: "wanted" => \&set_permission }, "$topdir");
467:
468:
469: }
470:
1.26 foxr 471: #-------------------------- Exit...
472: #
473: # Write the file if the error_file is defined. Regardless
474: # Exit with the status code.
475: #
476: sub Exit {
477: my ($code) = @_; # Status code.
478:
1.37 foxr 479: # TODO: Ensure the error file is owned/deletable by www:www:
480:
481: &disable_root_capability(); # We run unprivileged to write the error file.
482:
1.26 foxr 483: print "Exiting with status $code error file is $error_file\n" unless $noprint;
484: if($error_file) {
485: open(FH, ">$error_file");
486: print FH "$code\n";
487: close(FH);
488: }
489: exit $code;
490: }
1.16 harris41 491:
492: =head1 NAME
493:
494: lcuseradd - LON-CAPA setuid script to coordinate all actions
495: with adding a user with filesystem privileges (e.g. author)
496:
497: =head1 DESCRIPTION
498:
499: lcuseradd - LON-CAPA setuid script to coordinate all actions
500: with adding a user with filesystem privileges (e.g. author)
501:
502: =head1 README
503:
504: lcuseradd - LON-CAPA setuid script to coordinate all actions
505: with adding a user with filesystem privileges (e.g. author)
506:
507: =head1 PREREQUISITES
508:
509: =head1 COREQUISITES
510:
511: =pod OSNAMES
512:
513: linux
514:
515: =pod SCRIPT CATEGORIES
516:
517: LONCAPA/Administrative
518:
519: =cut
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