Return to lcpasswd CVS log

Up to [LON-CAPA] / loncom

trying to add error-checking to make sure invalid characters are not in the
user name or passwords.  lcuseradd appears to be basically working, but I
still need to implement the addition of passwords.  I cannot do this with
a system call to lcpasswd due to the restrictions of perl setuid scripts.L

    1: #!/usr/bin/perl
    2: #
    3: # lcpasswd
    4: #
    5: # Scott Harrison
    6: # SH: October 27, 2000
    7: # SH: October 28, 2000
    8: 
    9: use strict;
   10: 
   11: # This script is a setuid script that should
   12: # be run by user 'www'.  This script allows
   13: # for synchronous entry of passwords into
   14: # both the /etc/passwd and the /etc/smbpasswd
   15: # files.
   16: 
   17: # This script works under the same process control mechanism
   18: # as lcuseradd and lcpasswd, to make sure that only one of these
   19: # processes is running at any one time on the system.
   20: 
   21: # Standard input usage
   22: # First line is USERNAME
   23: # Second line is CURRENT PASSWORD
   24: # Third line is NEW PASSWORD
   25: 
   26: # Valid passwords must consist of the
   27: # ascii characters within the inclusive
   28: # range of 0x20 (32) to 0x7E (126).
   29: # These characters are:
   30: # SPACE and
   31: # !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
   32: # PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
   33: 
   34: # Valid user names must consist of ascii
   35: # characters that are alphabetical characters
   36: # (A-Z,a-z), numeric (0-9), or the underscore
   37: # mark (_). (Essentially, the perl regex \w).
   38: 
   39: # Command-line arguments
   40: # Yes, but be very careful here (don't pass shell commands)
   41: # and this is only supported to allow perl-system calls.
   42: 
   43: # Usage within code
   44: # Note: NEVER run as system("/home/httpd/perl/lcpasswd NAME OLDPWD NEWPWD")
   45: #
   46: # $exitcode=system("/home/httpd/perl/lcpasswd","NAME","OLDPWD","NEWPWD")/256;
   47: # print "uh-oh" if $exitcode;
   48: 
   49: # These are the exit codes.
   50: # ( (0,"ok"),
   51: #   (1,"User ID mismatch.  This program must be run as user 'www'"),
   52: #   (2,"Error. This program does not accept command-line arguments."),
   53: #   (3,"Error. Three lines need to be entered into standard input."),
   54: #   (4,"Error. Too many other simultaneous password change requests being made."),
   55: #   (5,"Error. User $username does not exist."),
   56: #   (6,"Error. Invalid entry of current password."),
   57: #   (7,"Error.  Root was not successfully enabled."),
   58: #   (8,"Error.  Cannot open /etc/passwd.") )
   59: 
   60: # Security
   61: $ENV{'PATH'}='/bin:/usr/bin'; # Nullify path information except for what smbpasswd needs
   62: $ENV{'BASH_ENV'}=''; # Nullify shell environment information.
   63: 
   64: # Do not print error messages if there are command-line arguments
   65: my $noprint=0;
   66: if (@ARGV) {
   67:     $noprint=1;
   68: }
   69: 
   70: # Read in /etc/passwd, and make sure this process is running from user=www
   71: open (IN, '</etc/passwd');
   72: my @lines=<IN>;
   73: close IN;
   74: my $wwwid;
   75: for my $l (@lines) {
   76:     chop $l;
   77:     my @F=split(/\:/,$l);
   78:     if ($F[0] eq 'www') {$wwwid=$F[2];}
   79: }
   80: if ($wwwid!=$<) {
   81:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
   82:     exit 1;
   83: }
   84: &disable_root_capability;
   85: 
   86: # Handle case of another lcpasswd process
   87: unless (&try_to_lock('/tmp/lock_lcpasswd')) {
   88:     print "Error. Too many other simultaneous password change requests being made.\n" unless $noprint;
   89:     exit 4;
   90: }
   91: 
   92: # Gather input.  Should only be 3 values.
   93: my @input;
   94: if (@ARGV==3) {
   95:     @input=@ARGV;
   96: }
   97: elsif (@ARGV) {
   98:     print("Error. This program needs 3 command-line arguments (username, old password, new password).\n") unless $noprint;
   99:     unlink('/tmp/lock_lcpasswd');
  100:     exit 2;
  101: }
  102: else {
  103:     @input=<>;
  104:     if (@input!=3) {
  105: 	print("Error. Three lines need to be entered into standard input.\n") unless $noprint;
  106: 	unlink('/tmp/lock_lcpasswd');
  107: 	exit 3;
  108:     }
  109:     map {chop} @input;
  110: }
  111: 
  112: my ($username,$oldpwd,$newpwd)=@input;
  113: $username=~/^(\w+)$/;
  114: my $safeusername=$1;
  115: if ($username ne $safeusername) {
  116:     print "Error. The user name specified has invalid characters.\n";
  117:     unlink('/tmp/lock_lcpasswd');
  118:     exit 9;
  119: }
  120: 
  121: 
  122: # Grab the line corresponding to username
  123: my ($userid,$useroldcryptpwd);
  124: my @F; my @U;
  125: for my $l (@lines) {
  126:     @F=split(/\:/,$l);
  127:     if ($F[0] eq $username) {($userid,$useroldcryptpwd)=($F[2],$F[1]); @U=@F;}
  128: }
  129: 
  130: # Verify existence of user
  131: if (!defined($userid)) {
  132:     print "Error. User $username does not exist.\n" unless $noprint;
  133:     unlink('/tmp/lock_lcpasswd');
  134:     exit 5;
  135: }
  136: 
  137: # Verify password entry
  138: if (crypt($oldpwd,$useroldcryptpwd) ne $useroldcryptpwd) {
  139:     print "Error. Invalid entry of current password.\n" unless $noprint;
  140:     unlink('/tmp/lock_lcpasswd');
  141:     exit 6;
  142: }
  143: 
  144: # Construct new password entry (random salt)
  145: my $newcryptpwd=crypt($newpwd,(join '', ('.', '/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]));
  146: $U[1]=$newcryptpwd;
  147: my $userline=join(':',@U);
  148: my $rootid=&enable_root_capability;
  149: if ($rootid!=0) {
  150:     print "Error.  Root was not successfully enabled.\n" unless $noprint;
  151:     unlink('/tmp/lock_lcpasswd');
  152:     exit 7;
  153: }
  154: open PASSWORDFILE, '>/etc/passwd' or (print("Error.  Cannot open /etc/passwd.\n") && unlink('/tmp/lock_lcpasswd') && exit(8));
  155: for my $l (@lines) {
  156:     @F=split(/\:/,$l);
  157:     if ($F[0] eq $username) {print PASSWORDFILE "$userline\n";}
  158:     else {print PASSWORDFILE "$l\n";}
  159: }
  160: close PASSWORDFILE;
  161: 
  162: ($>,$<)=(0,0); # fool smbpasswd here to think this is not a setuid environment
  163: unless (-e '/etc/smbpasswd') {
  164:     open (OUT,'>/etc/smbpasswd'); close OUT;
  165: }
  166: my $smbexist=0;
  167: open (IN, '</etc/smbpasswd');
  168: my @lines=<IN>;
  169: close IN;
  170: for my $l (@lines) {
  171:     chop $l;
  172:     my @F=split(/\:/,$l);
  173:     if ($F[0] eq $username) {$smbexist=1;}
  174: }
  175: unless ($smbexist) {
  176:     open(OUT,'>>/etc/smbpasswd');
  177:     print OUT join(':',($safeusername,$userid,'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX','','/home/'.$safeusername,'/bin/bash')) . "\n";
  178:     close OUT;
  179: }
  180: open(OUT,"|/usr/bin/smbpasswd -s $safeusername>/dev/null");
  181: print OUT $newpwd; print OUT "\n";
  182: print OUT $newpwd; print OUT "\n";
  183: close OUT;
  184: $<=$wwwid; # unfool the program
  185: &disable_root_capability;
  186: unlink('/tmp/lock_lcpasswd');
  187: exit 0;
  188: 
  189: # ----------------------------------------------------------- have setuid script run as root
  190: sub enable_root_capability {
  191:     if ($wwwid==$>) {
  192: 	($<,$>)=($>,$<);
  193: 	($(,$))=($),$();
  194:     }
  195:     else {
  196: 	# root capability is already enabled
  197:     }
  198:     return $>;
  199: }
  200: 
  201: # ----------------------------------------------------------- have setuid script run as www
  202: sub disable_root_capability {
  203:     if ($wwwid==$<) {
  204: 	($<,$>)=($>,$<);
  205: 	($(,$))=($),$();
  206:     }
  207:     else {
  208: 	# root capability is already disabled
  209:     }
  210: }
  211: 
  212: # ----------------------------------- make sure that another lcpasswd process isn't running
  213: sub try_to_lock {
  214:     my ($lockfile)=@_;
  215:     my $currentpid;
  216:     my $lastpid;
  217:     # Do not manipulate lock file as root
  218:     if ($>==0) {
  219: 	return 0;
  220:     }
  221:     # Try to generate lock file.
  222:     # Wait 3 seconds.  If same process id is in
  223:     # lock file, then assume lock file is stale, and
  224:     # go ahead.  If process id's fluctuate, try
  225:     # for a maximum of 10 times.
  226:     for (0..10) {
  227: 	if (-e $lockfile) {
  228: 	    open(LOCK,"<$lockfile");
  229: 	    $currentpid=<LOCK>;
  230: 	    close LOCK;
  231: 	    if ($currentpid==$lastpid) {
  232: 		last;
  233: 	    }
  234: 	    sleep 3;
  235: 	    $lastpid=$currentpid;
  236: 	}
  237: 	else {
  238: 	    last;
  239: 	}
  240: 	if ($_==10) {
  241: 	    return 0;
  242: 	}
  243:     }
  244:     open(LOCK,">$lockfile");
  245:     print LOCK $$;
  246:     close LOCK;
  247:     return 1;
  248: }