Annotation of loncom/lcuseradd, revision 1.43
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: #
1.43 ! raeburn 9: # $Id: lcuseradd,v 1.42 2011/10/24 21:30:09 www 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
1.42 www 52: # Second line is DOMAIN
1.3 harris41 53: # Third line is PASSWORD
1.42 www 54: # Fourth line is PASSWORD
55: # Fifth line is the name of a file to which an error code will be written.
1.26 foxr 56: # If the fourth line is omitted, no error file will be written.
57: # In either case, the program Exits with the code as its Exit status.
58: # The error file will just be a single line containing an
59: # error code.
60: #
61: #
1.15 harris41 62: #
1.42 www 63: # Command-line arguments [USERNAME] [DOMAIN] [PASSWORD] [PASSWORD]
1.15 harris41 64: # Yes, but be very careful here (don't pass shell commands)
65: # and this is only supported to allow perl-system calls.
66: #
1.7 harris41 67: # Valid passwords must consist of the
68: # ascii characters within the inclusive
69: # range of 0x20 (32) to 0x7E (126).
70: # These characters are:
71: # SPACE and
72: # !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
73: # PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
1.15 harris41 74: #
1.7 harris41 75: # Valid user names must consist of ascii
76: # characters that are alphabetical characters
77: # (A-Z,a-z), numeric (0-9), or the underscore
78: # mark (_). (Essentially, the perl regex \w).
1.15 harris41 79: # User names must begin with an alphabetical character
80: # (A-Z,a-z).
1.7 harris41 81:
1.15 harris41 82: # ---------------------------------- Example usage inside another piece of code
1.4 harris41 83: # Usage within code
84: #
1.26 foxr 85: # $Exitcode=
1.42 www 86: # system("/home/httpd/perl/lcuseradd","NAME","DOMAIN","PASSWORD1","PASSWORD2")/256;
1.26 foxr 87: # print "uh-oh" if $Exitcode;
1.4 harris41 88:
1.15 harris41 89: # ---------------------------------------------------- Description of functions
90: # enable_root_capability() : have setuid script run as root
91: # disable_root_capability() : have setuid script run as www
92: # try_to_lock() : make sure that another lcpasswd process isn't running
93:
94: # ------------------------------------------------------------------ Exit codes
1.26 foxr 95: # These are the Exit codes.
1.13 harris41 96: # ( (0,"ok"),
97: # (1,"User ID mismatch. This program must be run as user 'www'"),
1.15 harris41 98: # (2,"Error. This program needs 3 command-line arguments (username, ".
99: # "password 1, password 2)."),
1.13 harris41 100: # (3,"Error. Three lines should be entered into standard input."),
1.15 harris41 101: # (4,"Error. Too many other simultaneous password change requests being ".
102: # "made."),
1.13 harris41 103: # (5,"Error. User $username does not exist."),
104: # (6,"Error. Could not make www a member of the group \"$safeusername\"."),
105: # (7,"Error. Root was not successfully enabled.),
1.15 harris41 106: # (8,"Error. Cannot set password."),
1.13 harris41 107: # (9,"Error. The user name specified has invalid characters."),
108: # (10,"Error. A password entry had an invalid character."),
109: # (11,"Error. User already exists.),
1.15 harris41 110: # (12,"Error. Something went wrong with the addition of user ".
111: # "\"$safeusername\"."),
1.13 harris41 112: # (13,"Error. Password mismatch."),
1.38 raeburn 113: # (14, "Error filename is invalid"),
114: # (15, "Error. Could not add home directory.")
1.4 harris41 115:
1.15 harris41 116: # ------------------------------------------------------------- Initializations
1.1 harris41 117: # Security
1.15 harris41 118: $ENV{'PATH'}='/bin/:/usr/bin:/usr/local/sbin:/home/httpd/perl'; # Nullify path
119: # information
1.16 harris41 120: delete @ENV{qw(IFS CDPATH ENV BASH_ENV)}; # nullify potential taints
1.2 harris41 121:
1.15 harris41 122: # Do not print error messages.
123: my $noprint=1;
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 $noprint;
1.4 harris41 160: unlink('/tmp/lock_lcpasswd');
1.26 foxr 161: &Exit(3);
1.4 harris41 162: }
1.19 harris41 163: foreach (@input) {chomp;}
1.4 harris41 164: }
165:
1.42 www 166: my ($username,$domain,$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 $noprint;
1.22 foxr 172:
1.42 www 173: print "Domain = ".$domain."\n" unless $noprint;
174:
1.15 harris41 175: if (($username ne $safeusername) or ($safeusername!~/^[A-Za-z]/)) {
1.22 foxr 176: print "Error. The user name specified $username $safeusername has invalid characters.\n"
1.15 harris41 177: unless $noprint;
1.8 harris41 178: unlink('/tmp/lock_lcpasswd');
1.26 foxr 179: &Exit(9);
1.8 harris41 180: }
181: my $pbad=0;
1.19 harris41 182: foreach (split(//,$password1)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}}
183: foreach (split(//,$password2)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}}
1.8 harris41 184: if ($pbad) {
1.26 foxr 185: print "Error. A password entry had an invalid character.\n" unless $noprint;
1.8 harris41 186: unlink('/tmp/lock_lcpasswd');
1.26 foxr 187: &Exit(10);
1.8 harris41 188: }
1.5 harris41 189:
1.26 foxr 190: #
191: # Safe the filename. For our case, it must only have alpha, numeric, period
192: # and path sparators..
193: #
194:
195: print "Error file is $error_file \n" unless $noprint;
196:
197: if($error_file) {
198: if($error_file =~ /^([(\w)(\d)\.\/]+)$/) {
199: print "Error file matched pattern $error_file : $1\n" unless $noprint;
200: my $safe_error_file = $1; # Untainted I think.
201: print "Error file after transform $safe_error_file\n"
202: unless $noprint;
203: if($error_file == $safe_error_file) {
204: $error_file = $safe_error_file; # untainted error_file.
205: } else {
206: $error_file ="";
207: print "Invalid error filename\n" unless $noprint;
208: Exit(14);
209: }
210:
1.28 foxr 211: } else {
1.26 foxr 212: $error_file="";
213: print "Invalid error filename\n" unless $noprint;
214: Exit(14);
215: }
216: }
217:
218:
1.31 foxr 219: # -- Only add the user if they are >not< in /etc/passwd.
220: # Used to look for the ability to create a new directory for the
221: # user, however that disallows authentication changes from i
222: # internal->fs.. so just check the passwd file instead.
223: #
1.34 foxr 224: my $not_found = system("cut -d: -f1 /etc/passwd | grep -q \"^$safeusername\$\" ");
1.31 foxr 225: if (!$not_found) {
226: print "Error user already exists\n" unless $noprint;
1.7 harris41 227: unlink('/tmp/lock_lcpasswd');
1.26 foxr 228: &Exit(11);
1.7 harris41 229: }
230:
1.31 foxr 231:
232:
1.15 harris41 233: # -- Only add user if the two password arguments match.
1.23 foxr 234:
1.5 harris41 235: if ($password1 ne $password2) {
1.6 harris41 236: print "Error. Password mismatch.\n" unless $noprint;
1.5 harris41 237: unlink('/tmp/lock_lcpasswd');
1.26 foxr 238: &Exit(13);
1.5 harris41 239: }
1.23 foxr 240: print "enabling root\n" unless $noprint;
1.15 harris41 241: # ---------------------------------- Start running script with root permissions
1.4 harris41 242: &enable_root_capability;
243:
1.38 raeburn 244: # ------------------- Add group and user, and make www a member of the group
245: # -- Add group
246:
247: print "adding group: $safeusername \n" unless $noprint;
248: my $status = system('/usr/sbin/groupadd', $safeusername);
249: if ($status) {
250: print "Error. Something went wrong with the addition of group ".
251: "\"$safeusername\".\n" unless $noprint;
252: print "Final status of groupadd = $status\n";
253: unlink('/tmp/lock_lcpasswd');
254: &Exit(12);
255: }
256: my $gid = getgrnam($safeusername);
257:
1.15 harris41 258: # -- Add user
1.23 foxr 259:
260: print "adding user: $safeusername \n" unless $noprint;
1.38 raeburn 261: my $status = system('/usr/sbin/useradd','-c','LON-CAPA user','-g',$gid,$safeusername);
1.23 foxr 262: if ($status) {
1.15 harris41 263: print "Error. Something went wrong with the addition of user ".
264: "\"$safeusername\".\n" unless $noprint;
1.38 raeburn 265: system("/usr/sbin/groupdel $safeusername");
1.37 foxr 266: print "Final status of useradd = $status\n";
1.4 harris41 267: unlink('/tmp/lock_lcpasswd');
1.26 foxr 268: &Exit(12);
1.4 harris41 269: }
1.36 albertel 270:
1.23 foxr 271: print "Done adding user\n" unless $noprint;
1.7 harris41 272: # Make www a member of that user group.
1.26 foxr 273: my $groups=`/usr/bin/groups www` or &Exit(6);
1.27 albertel 274: # untaint
1.29 albertel 275: my ($safegroups)=($groups=~/:\s*([\s\w]+)/);
1.27 albertel 276: $groups=$safegroups;
1.17 harris41 277: chomp $groups; $groups=~s/^\S+\s+\:\s+//;
278: my @grouplist=split(/\s+/,$groups);
279: my @ugrouplist=grep {!/www|$safeusername/} @grouplist;
280: my $gl=join(',',(@ugrouplist,$safeusername));
1.38 raeburn 281: print "Putting www in user's group\n" unless $noprint;
1.17 harris41 282: if (system('/usr/sbin/usermod','-G',$gl,'www')) {
1.15 harris41 283: print "Error. Could not make www a member of the group ".
284: "\"$safeusername\".\n" unless $noprint;
1.5 harris41 285: unlink('/tmp/lock_lcpasswd');
1.26 foxr 286: &Exit(6);
1.5 harris41 287: }
288:
1.15 harris41 289: # ---------------------------------------------------------------- Set password
290: # Set password with lcpasswd (which creates smbpasswd entry).
1.2 harris41 291:
1.15 harris41 292: unlink('/tmp/lock_lcpasswd');
293: &disable_root_capability;
1.16 harris41 294: ($>,$<)=($wwwid,$wwwid);
1.23 foxr 295: print "Opening lcpasswd pipeline\n" unless $noprint;
1.16 harris41 296: open OUT,"|/home/httpd/perl/lcpasswd";
1.15 harris41 297: print OUT $safeusername;
298: print OUT "\n";
299: print OUT $password1;
300: print OUT "\n";
301: print OUT $password1;
302: print OUT "\n";
303: close OUT;
304: if ($?) {
1.26 foxr 305: print "abnormal Exit from close lcpasswd\n" unless $noprint;
306: &Exit(8);
1.8 harris41 307: }
1.18 harris41 308: ($>,$<)=($wwwid,0);
1.15 harris41 309: &enable_root_capability;
1.8 harris41 310:
1.38 raeburn 311: # Check if home directory exists for user
312: # If not, create one.
313: if (!-e "/home/$safeusername") {
314: if (!mkdir("/home/$safeusername",0710)) {
315: print "Error. Could not add home directory for ".
316: "\"$safeusername\".\n" unless $noprint;
317: unlink('/tmp/lock_lcpasswd');
318: &Exit(15);
319: }
320: }
1.20 foxr 321:
1.24 www 322: # ---------------------------------------------------- Gracefull Apache Restart
1.40 raeburn 323: my $pidfile;
1.24 www 324: if (-e '/var/run/httpd.pid') {
1.40 raeburn 325: $pidfile = '/var/run/httpd.pid';
326: } elsif (-e '/var/run/httpd2.pid') { #Apache 2 on SuSE 10.1 and SLES10
327: $pidfile = '/var/run/httpd2.pid';
328: }
329:
330: if ($pidfile) {
1.24 www 331: print "lcuseradd Apache restart\n" unless $noprint;
1.41 albertel 332: open(PID,"<$pidfile");
1.24 www 333: my $pid=<PID>;
334: close(PID);
1.39 albertel 335: $pid=~ /(\D+)/;
1.35 foxr 336: my $safepid = $1;
1.24 www 337: if ($pid) {
1.27 albertel 338: system('kill','-USR1',"$safepid");
1.24 www 339: }
340: }
1.15 harris41 341: # -------------------------------------------------------- Exit script
1.26 foxr 342: print "lcuseradd Exiting\n" unless $noprint;
1.8 harris41 343: &disable_root_capability;
1.26 foxr 344: &Exit(0);
1.1 harris41 345:
1.15 harris41 346: # ---------------------------------------------- Have setuid script run as root
1.5 harris41 347: sub enable_root_capability {
348: if ($wwwid==$>) {
1.23 foxr 349: ($<,$>)=($>,0);
350: ($(,$))=($),0);
1.28 foxr 351: } else {
1.5 harris41 352: # root capability is already enabled
353: }
1.41 albertel 354: if ($wwwid == $>) {
355: print("Failed to become root\n") unless $noprint;
356: } else {
357: print("Became root\n") unless $noprint;
358: }
1.5 harris41 359: return $>;
360: }
361:
1.15 harris41 362: # ----------------------------------------------- Have setuid script run as www
1.5 harris41 363: sub disable_root_capability {
364: if ($wwwid==$<) {
365: ($<,$>)=($>,$<);
366: ($(,$))=($),$();
1.28 foxr 367: } else {
1.5 harris41 368: # root capability is already disabled
369: }
370: }
371:
1.15 harris41 372: # ----------------------- Make sure that another lcpasswd process isn't running
1.5 harris41 373: sub try_to_lock {
374: my ($lockfile)=@_;
375: my $currentpid;
376: my $lastpid;
377: # Do not manipulate lock file as root
378: if ($>==0) {
379: return 0;
380: }
381: # Try to generate lock file.
382: # Wait 3 seconds. If same process id is in
383: # lock file, then assume lock file is stale, and
384: # go ahead. If process id's fluctuate, try
385: # for a maximum of 10 times.
386: for (0..10) {
387: if (-e $lockfile) {
388: open(LOCK,"<$lockfile");
389: $currentpid=<LOCK>;
390: close LOCK;
391: if ($currentpid==$lastpid) {
392: last;
393: }
394: sleep 3;
395: $lastpid=$currentpid;
1.28 foxr 396: } else {
1.5 harris41 397: last;
398: }
399: if ($_==10) {
400: return 0;
401: }
402: }
403: open(LOCK,">$lockfile");
404: print LOCK $$;
405: close LOCK;
406: return 1;
407: }
1.35 foxr 408: # Called by File::Find::find for each file examined.
409: #
410: # Untaint the file and, if it is a directory,
411: # chmod it to 02770
412: #
413: sub set_permission {
414: $File::Find::name =~ /^(.*)$/;
415: my $safe_name = $1; # Untainted filename...
416:
417: print "$safe_name" unless $noprint;
418: if(-d $safe_name) {
419: print " - directory" unless $noprint;
420: chmod(02770, $safe_name);
421: }
422: print "\n" unless $noprint;
423:
424: }
425:
1.26 foxr 426: #-------------------------- Exit...
427: #
428: # Write the file if the error_file is defined. Regardless
429: # Exit with the status code.
430: #
431: sub Exit {
432: my ($code) = @_; # Status code.
433:
1.37 foxr 434: # TODO: Ensure the error file is owned/deletable by www:www:
435:
436: &disable_root_capability(); # We run unprivileged to write the error file.
437:
1.26 foxr 438: print "Exiting with status $code error file is $error_file\n" unless $noprint;
439: if($error_file) {
440: open(FH, ">$error_file");
441: print FH "$code\n";
442: close(FH);
443: }
444: exit $code;
445: }
1.16 harris41 446:
447: =head1 NAME
448:
449: lcuseradd - LON-CAPA setuid script to coordinate all actions
450: with adding a user with filesystem privileges (e.g. author)
451:
452: =head1 DESCRIPTION
453:
454: lcuseradd - LON-CAPA setuid script to coordinate all actions
455: with adding a user with filesystem privileges (e.g. author)
456:
457: =head1 README
458:
459: lcuseradd - LON-CAPA setuid script to coordinate all actions
460: with adding a user with filesystem privileges (e.g. author)
461:
462: =head1 PREREQUISITES
463:
464: =head1 COREQUISITES
465:
466: =pod OSNAMES
467:
468: linux
469:
470: =pod SCRIPT CATEGORIES
471:
472: LONCAPA/Administrative
473:
474: =cut
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