Annotation of loncom/lcuseradd, revision 1.31
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: #
1.31 ! foxr 9: # $Id: lcuseradd,v 1.30 2004/09/02 19:04:00 albertel 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;
35:
1.15 harris41 36: # ------------------------------------------------------- Description of script
37: #
1.1 harris41 38: # This script is a setuid script that should
1.20 foxr 39: # be run by user 'www'. It creates a /home/USERNAME directory.
1.15 harris41 40: # It adds a user to the unix system.
1.2 harris41 41: # Passwords are set with lcpasswd.
42: # www becomes a member of this user group.
1.1 harris41 43:
1.15 harris41 44: # -------------- Invoking script (standard input versus command-line arguments)
1.26 foxr 45: # Otherwise sensitive information will be available to ps-ers for
46: # a small but exploitable time window.
1.15 harris41 47: #
48: # Standard input (STDIN) usage
1.1 harris41 49: # First line is USERNAME
50: # Second line is PASSWORD
1.3 harris41 51: # Third line is PASSWORD
1.26 foxr 52: # Fouth line is the name of a file to which an error code will be written.
53: # If the fourth line is omitted, no error file will be written.
54: # In either case, the program Exits with the code as its Exit status.
55: # The error file will just be a single line containing an
56: # error code.
57: #
58: #
1.15 harris41 59: #
60: # Command-line arguments [USERNAME] [PASSWORD] [PASSWORD]
61: # Yes, but be very careful here (don't pass shell commands)
62: # and this is only supported to allow perl-system calls.
63: #
1.7 harris41 64: # Valid passwords must consist of the
65: # ascii characters within the inclusive
66: # range of 0x20 (32) to 0x7E (126).
67: # These characters are:
68: # SPACE and
69: # !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
70: # PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
1.15 harris41 71: #
1.7 harris41 72: # Valid user names must consist of ascii
73: # characters that are alphabetical characters
74: # (A-Z,a-z), numeric (0-9), or the underscore
75: # mark (_). (Essentially, the perl regex \w).
1.15 harris41 76: # User names must begin with an alphabetical character
77: # (A-Z,a-z).
1.7 harris41 78:
1.15 harris41 79: # ---------------------------------- Example usage inside another piece of code
1.4 harris41 80: # Usage within code
81: #
1.26 foxr 82: # $Exitcode=
1.15 harris41 83: # system("/home/httpd/perl/lcuseradd","NAME","PASSWORD1","PASSWORD2")/256;
1.26 foxr 84: # print "uh-oh" if $Exitcode;
1.4 harris41 85:
1.15 harris41 86: # ---------------------------------------------------- Description of functions
87: # enable_root_capability() : have setuid script run as root
88: # disable_root_capability() : have setuid script run as www
89: # try_to_lock() : make sure that another lcpasswd process isn't running
90:
91: # ------------------------------------------------------------------ Exit codes
1.26 foxr 92: # These are the Exit codes.
1.13 harris41 93: # ( (0,"ok"),
94: # (1,"User ID mismatch. This program must be run as user 'www'"),
1.15 harris41 95: # (2,"Error. This program needs 3 command-line arguments (username, ".
96: # "password 1, password 2)."),
1.13 harris41 97: # (3,"Error. Three lines should be entered into standard input."),
1.15 harris41 98: # (4,"Error. Too many other simultaneous password change requests being ".
99: # "made."),
1.13 harris41 100: # (5,"Error. User $username does not exist."),
101: # (6,"Error. Could not make www a member of the group \"$safeusername\"."),
102: # (7,"Error. Root was not successfully enabled.),
1.15 harris41 103: # (8,"Error. Cannot set password."),
1.13 harris41 104: # (9,"Error. The user name specified has invalid characters."),
105: # (10,"Error. A password entry had an invalid character."),
106: # (11,"Error. User already exists.),
1.15 harris41 107: # (12,"Error. Something went wrong with the addition of user ".
108: # "\"$safeusername\"."),
1.13 harris41 109: # (13,"Error. Password mismatch."),
1.26 foxr 110: # (14, "Error filename is invalid")
1.4 harris41 111:
1.15 harris41 112: # ------------------------------------------------------------- Initializations
1.1 harris41 113: # Security
1.15 harris41 114: $ENV{'PATH'}='/bin/:/usr/bin:/usr/local/sbin:/home/httpd/perl'; # Nullify path
115: # information
1.16 harris41 116: delete @ENV{qw(IFS CDPATH ENV BASH_ENV)}; # nullify potential taints
1.2 harris41 117:
1.15 harris41 118: # Do not print error messages.
119: my $noprint=1;
120:
1.26 foxr 121: # Error file:
122:
123: my $error_file; # This is either the error file name or undef.
124:
1.23 foxr 125: print "In lcuseradd\n" unless $noprint;
126:
1.15 harris41 127: # ----------------------------- Make sure this process is running from user=www
128: my $wwwid=getpwnam('www');
129: &disable_root_capability;
130: if ($wwwid!=$>) {
131: print("User ID mismatch. This program must be run as user 'www'\n")
132: unless $noprint;
1.26 foxr 133: &Exit(1);
1.4 harris41 134: }
1.15 harris41 135:
136: # ----------------------------------- Start running script with www permissions
1.4 harris41 137: &disable_root_capability;
138:
1.15 harris41 139: # --------------------------- Handle case of another lcpasswd process (locking)
1.4 harris41 140: unless (&try_to_lock("/tmp/lock_lcpasswd")) {
1.15 harris41 141: print "Error. Too many other simultaneous password change requests being ".
142: "made.\n" unless $noprint;
1.26 foxr 143: &Exit(4);
1.4 harris41 144: }
145:
1.15 harris41 146: # ------- Error-check input, need 3 values (user name, password 1, password 2).
1.4 harris41 147: my @input;
1.26 foxr 148: if (@ARGV>=3) {
1.4 harris41 149: @input=@ARGV;
1.28 foxr 150: } elsif (@ARGV) {
1.26 foxr 151: print("Error. This program needs at least 3 command-line arguments (username, ".
152: "password 1, password 2 [errorfile]).\n") unless $noprint;
1.4 harris41 153: unlink('/tmp/lock_lcpasswd');
1.26 foxr 154: &Exit(2);
1.28 foxr 155: } else {
1.4 harris41 156: @input=<>;
1.26 foxr 157: if (@input < 3) {
158: print("Error. At least three lines should be entered into standard input.\n")
1.15 harris41 159: unless $noprint;
1.4 harris41 160: unlink('/tmp/lock_lcpasswd');
1.26 foxr 161: &Exit(3);
1.4 harris41 162: }
1.19 harris41 163: foreach (@input) {chomp;}
1.4 harris41 164: }
165:
1.26 foxr 166: my ($username,$password1,$password2, $error_file)=@input;
1.23 foxr 167: print "Username = ".$username."\n" unless $noprint;
1.4 harris41 168: $username=~/^(\w+)$/;
1.22 foxr 169: print "Username after substitution - ".$username unless $noprint;
1.4 harris41 170: my $safeusername=$1;
1.23 foxr 171: print "Safe username = $safeusername \n" unless $noprint;
1.22 foxr 172:
1.15 harris41 173: if (($username ne $safeusername) or ($safeusername!~/^[A-Za-z]/)) {
1.22 foxr 174: print "Error. The user name specified $username $safeusername has invalid characters.\n"
1.15 harris41 175: unless $noprint;
1.8 harris41 176: unlink('/tmp/lock_lcpasswd');
1.26 foxr 177: &Exit(9);
1.8 harris41 178: }
179: my $pbad=0;
1.19 harris41 180: foreach (split(//,$password1)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}}
181: foreach (split(//,$password2)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}}
1.8 harris41 182: if ($pbad) {
1.26 foxr 183: print "Error. A password entry had an invalid character.\n" unless $noprint;
1.8 harris41 184: unlink('/tmp/lock_lcpasswd');
1.26 foxr 185: &Exit(10);
1.8 harris41 186: }
1.5 harris41 187:
1.26 foxr 188: #
189: # Safe the filename. For our case, it must only have alpha, numeric, period
190: # and path sparators..
191: #
192:
193: print "Error file is $error_file \n" unless $noprint;
194:
195: if($error_file) {
196: if($error_file =~ /^([(\w)(\d)\.\/]+)$/) {
197: print "Error file matched pattern $error_file : $1\n" unless $noprint;
198: my $safe_error_file = $1; # Untainted I think.
199: print "Error file after transform $safe_error_file\n"
200: unless $noprint;
201: if($error_file == $safe_error_file) {
202: $error_file = $safe_error_file; # untainted error_file.
203: } else {
204: $error_file ="";
205: print "Invalid error filename\n" unless $noprint;
206: Exit(14);
207: }
208:
1.28 foxr 209: } else {
1.26 foxr 210: $error_file="";
211: print "Invalid error filename\n" unless $noprint;
212: Exit(14);
213: }
214: }
215:
216:
1.31 ! foxr 217: # -- Only add the user if they are >not< in /etc/passwd.
! 218: # Used to look for the ability to create a new directory for the
! 219: # user, however that disallows authentication changes from i
! 220: # internal->fs.. so just check the passwd file instead.
! 221: #
! 222: my $not_found = system("grep -q $safeusername: /etc/passwd");
! 223: if (!$not_found) {
! 224: print "Error user already exists\n" unless $noprint;
1.7 harris41 225: unlink('/tmp/lock_lcpasswd');
1.26 foxr 226: &Exit(11);
1.7 harris41 227: }
228:
1.31 ! foxr 229:
! 230:
1.15 harris41 231: # -- Only add user if the two password arguments match.
1.23 foxr 232:
1.5 harris41 233: if ($password1 ne $password2) {
1.6 harris41 234: print "Error. Password mismatch.\n" unless $noprint;
1.5 harris41 235: unlink('/tmp/lock_lcpasswd');
1.26 foxr 236: &Exit(13);
1.5 harris41 237: }
1.23 foxr 238: print "enabling root\n" unless $noprint;
1.15 harris41 239: # ---------------------------------- Start running script with root permissions
1.4 harris41 240: &enable_root_capability;
241:
1.15 harris41 242: # ------------------- Add user and make www a member of the user-specific group
243: # -- Add user
1.23 foxr 244:
245: print "adding user: $safeusername \n" unless $noprint;
246: my $status = system('/usr/sbin/useradd','-c','LON-CAPA user',$safeusername);
247: if ($status) {
1.15 harris41 248: print "Error. Something went wrong with the addition of user ".
249: "\"$safeusername\".\n" unless $noprint;
1.23 foxr 250: print "Final status of useradd = $status";
1.4 harris41 251: unlink('/tmp/lock_lcpasswd');
1.26 foxr 252: &Exit(12);
1.4 harris41 253: }
1.23 foxr 254: print "Done adding user\n" unless $noprint;
1.7 harris41 255: # Make www a member of that user group.
1.26 foxr 256: my $groups=`/usr/bin/groups www` or &Exit(6);
1.27 albertel 257: # untaint
1.29 albertel 258: my ($safegroups)=($groups=~/:\s*([\s\w]+)/);
1.27 albertel 259: $groups=$safegroups;
1.17 harris41 260: chomp $groups; $groups=~s/^\S+\s+\:\s+//;
261: my @grouplist=split(/\s+/,$groups);
262: my @ugrouplist=grep {!/www|$safeusername/} @grouplist;
263: my $gl=join(',',(@ugrouplist,$safeusername));
1.23 foxr 264: print "Putting user in its own group\n" unless $noprint;
1.17 harris41 265: if (system('/usr/sbin/usermod','-G',$gl,'www')) {
1.15 harris41 266: print "Error. Could not make www a member of the group ".
267: "\"$safeusername\".\n" unless $noprint;
1.5 harris41 268: unlink('/tmp/lock_lcpasswd');
1.26 foxr 269: &Exit(6);
1.5 harris41 270: }
271:
1.15 harris41 272: # ---------------------------------------------------------------- Set password
273: # Set password with lcpasswd (which creates smbpasswd entry).
1.2 harris41 274:
1.15 harris41 275: unlink('/tmp/lock_lcpasswd');
276: &disable_root_capability;
1.16 harris41 277: ($>,$<)=($wwwid,$wwwid);
1.23 foxr 278: print "Opening lcpasswd pipeline\n" unless $noprint;
1.16 harris41 279: open OUT,"|/home/httpd/perl/lcpasswd";
1.15 harris41 280: print OUT $safeusername;
281: print OUT "\n";
282: print OUT $password1;
283: print OUT "\n";
284: print OUT $password1;
285: print OUT "\n";
286: close OUT;
287: if ($?) {
1.26 foxr 288: print "abnormal Exit from close lcpasswd\n" unless $noprint;
289: &Exit(8);
1.8 harris41 290: }
1.18 harris41 291: ($>,$<)=($wwwid,0);
1.15 harris41 292: &enable_root_capability;
1.8 harris41 293:
1.20 foxr 294: # -- Don't add public_html... that can be added either by the user
295: # or by lchtmldir when the user is granted an authorship role.
296:
1.15 harris41 297: # ------------------------------ Make final modifications to the user directory
298: # -- Add a public_html file with a stand-in index.html file
1.8 harris41 299:
1.21 foxr 300: system('/bin/chmod','-R','0660',"/home/$safeusername");
301: system('/bin/chmod','0710',"/home/$safeusername");
302: mkdir "/home/$safeusername/public_html",0755;
303: system('/bin/chmod','02770',"/home/$safeusername/public_html");
304: open OUT,">/home/$safeusername/public_html/index.html";
305: print OUT<<END;
306: <html>
307: <head>
308: <title>$safeusername</title>
309: </head>
310: <body>
1.24 www 311: <h1>Construction Space</h1>
312: <h3>$safeusername</h3>
1.21 foxr 313: </body>
314: </html>
315: END
316: close OUT;
1.20 foxr 317:
1.24 www 318: print "lcuseradd ownership\n" unless $noprint;
1.11 harris41 319: system('/bin/chown','-R',"$safeusername:$safeusername","/home/$safeusername");
1.24 www 320: # ---------------------------------------------------- Gracefull Apache Restart
321: if (-e '/var/run/httpd.pid') {
322: print "lcuseradd Apache restart\n" unless $noprint;
323: open(PID,'/var/run/httpd.pid');
324: my $pid=<PID>;
325: close(PID);
1.27 albertel 326: my ($safepid)=($pid=~s/(\D+)//g);
1.24 www 327: if ($pid) {
1.27 albertel 328: system('kill','-USR1',"$safepid");
1.24 www 329: }
330: }
1.15 harris41 331: # -------------------------------------------------------- Exit script
1.26 foxr 332: print "lcuseradd Exiting\n" unless $noprint;
1.8 harris41 333: &disable_root_capability;
1.26 foxr 334: &Exit(0);
1.1 harris41 335:
1.15 harris41 336: # ---------------------------------------------- Have setuid script run as root
1.5 harris41 337: sub enable_root_capability {
338: if ($wwwid==$>) {
1.23 foxr 339: ($<,$>)=($>,0);
340: ($(,$))=($),0);
1.28 foxr 341: } else {
1.5 harris41 342: # root capability is already enabled
343: }
344: return $>;
345: }
346:
1.15 harris41 347: # ----------------------------------------------- Have setuid script run as www
1.5 harris41 348: sub disable_root_capability {
349: if ($wwwid==$<) {
350: ($<,$>)=($>,$<);
351: ($(,$))=($),$();
1.28 foxr 352: } else {
1.5 harris41 353: # root capability is already disabled
354: }
355: }
356:
1.15 harris41 357: # ----------------------- Make sure that another lcpasswd process isn't running
1.5 harris41 358: sub try_to_lock {
359: my ($lockfile)=@_;
360: my $currentpid;
361: my $lastpid;
362: # Do not manipulate lock file as root
363: if ($>==0) {
364: return 0;
365: }
366: # Try to generate lock file.
367: # Wait 3 seconds. If same process id is in
368: # lock file, then assume lock file is stale, and
369: # go ahead. If process id's fluctuate, try
370: # for a maximum of 10 times.
371: for (0..10) {
372: if (-e $lockfile) {
373: open(LOCK,"<$lockfile");
374: $currentpid=<LOCK>;
375: close LOCK;
376: if ($currentpid==$lastpid) {
377: last;
378: }
379: sleep 3;
380: $lastpid=$currentpid;
1.28 foxr 381: } else {
1.5 harris41 382: last;
383: }
384: if ($_==10) {
385: return 0;
386: }
387: }
388: open(LOCK,">$lockfile");
389: print LOCK $$;
390: close LOCK;
391: return 1;
392: }
1.26 foxr 393: #-------------------------- Exit...
394: #
395: # Write the file if the error_file is defined. Regardless
396: # Exit with the status code.
397: #
398: sub Exit {
399: my ($code) = @_; # Status code.
400:
401: print "Exiting with status $code error file is $error_file\n" unless $noprint;
402: if($error_file) {
403: open(FH, ">$error_file");
404: print FH "$code\n";
405: close(FH);
406: }
407: exit $code;
408: }
1.16 harris41 409:
410: =head1 NAME
411:
412: lcuseradd - LON-CAPA setuid script to coordinate all actions
413: with adding a user with filesystem privileges (e.g. author)
414:
415: =head1 DESCRIPTION
416:
417: lcuseradd - LON-CAPA setuid script to coordinate all actions
418: with adding a user with filesystem privileges (e.g. author)
419:
420: =head1 README
421:
422: lcuseradd - LON-CAPA setuid script to coordinate all actions
423: with adding a user with filesystem privileges (e.g. author)
424:
425: =head1 PREREQUISITES
426:
427: =head1 COREQUISITES
428:
429: =pod OSNAMES
430:
431: linux
432:
433: =pod SCRIPT CATEGORIES
434:
435: LONCAPA/Administrative
436:
437: =cut
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