Annotation of loncom/lcpasswd, revision 1.21

1.1       harris41    1: #!/usr/bin/perl
1.13      harris41    2: # The Learning Online Network with CAPA
                      3: #
                      4: # lcpasswd - LON-CAPA setuid script to synchronously change all
                      5: #            filesystem-related passwords (samba, unix, etc)
1.3       harris41    6: #
1.15      matthew     7: # YEAR=2002
                      8: # 02/19 Matthew Hall
1.13      harris41    9: #
1.21    ! albertel   10: # $Id: lcpasswd,v 1.20 2005/03/26 20:40:18 albertel Exp $
1.13      harris41   11: ###
1.12      harris41   12: 
                     13: ###############################################################################
                     14: ##                                                                           ##
                     15: ## ORGANIZATION OF THIS PERL SCRIPT                                          ##
                     16: ##                                                                           ##
                     17: ## 1. Description of script                                                  ##
                     18: ## 2. Invoking script (standard input only)                                  ##
                     19: ## 3. Example usage inside another piece of code                             ##
                     20: ## 4. Description of functions                                               ##
                     21: ## 5. Exit codes                                                             ##
                     22: ##                                                                           ##
                     23: ###############################################################################
1.1       harris41   24: 
                     25: use strict;
                     26: 
1.12      harris41   27: # ------------------------------------------------------- Description of script
                     28: #
1.1       harris41   29: # This script is a setuid script that should
1.4       harris41   30: # be run by user 'www'.  This script allows
                     31: # for synchronous entry of passwords into
                     32: # both the /etc/passwd and the /etc/smbpasswd
                     33: # files.
1.12      harris41   34: #
1.5       harris41   35: # This script works under the same process control mechanism
                     36: # as lcuseradd and lcpasswd, to make sure that only one of these
                     37: # processes is running at any one time on the system.
                     38: 
1.12      harris41   39: # --------------------------------------- Invoking script (standard input only)
                     40: #
1.1       harris41   41: # Standard input usage
                     42: # First line is USERNAME
1.16      matthew    43: # Second line is NEW PASSWORD
1.1       harris41   44: # Third line is NEW PASSWORD
1.12      harris41   45: #
1.8       harris41   46: # Valid passwords must consist of the
                     47: # ascii characters within the inclusive
                     48: # range of 0x20 (32) to 0x7E (126).
                     49: # These characters are:
                     50: # SPACE and
                     51: # !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
                     52: # PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
1.12      harris41   53: #
1.8       harris41   54: # Valid user names must consist of ascii
                     55: # characters that are alphabetical characters
                     56: # (A-Z,a-z), numeric (0-9), or the underscore
                     57: # mark (_). (Essentially, the perl regex \w).
1.12      harris41   58: # User names must begin with an alphabetical character
                     59: # (A-Z,a-z).
1.8       harris41   60: 
1.12      harris41   61: # ---------------------------------------------------- Description of functions
                     62: # enable_root_capability() : have setuid script run as root
                     63: # disable_root_capability() : have setuid script run as www
                     64: # try_to_lock() : make sure that another lcpasswd process isn't running
1.4       harris41   65: 
1.12      harris41   66: # ------------------------------------------------------------------ Exit codes
1.4       harris41   67: # These are the exit codes.
                     68: # ( (0,"ok"),
1.7       harris41   69: #   (1,"User ID mismatch.  This program must be run as user 'www'"),
1.12      harris41   70: #   (2,"Error. This program needs 3 command-line arguments (username, old ".
                     71: #       password, new password)."),
1.6       harris41   72: #   (3,"Error. Three lines need to be entered into standard input."),
1.12      harris41   73: #   (4,"Error. Too many other simultaneous password change requests being ".
                     74: #       made."),
1.6       harris41   75: #   (5,"Error. User $username does not exist."),
                     76: #   (6,"Error. Invalid entry of current password."),
1.10      harris41   77: #   (7,"Error. Root was not successfully enabled."),
1.12      harris41   78: #   (8,"Error. Cannot set password."),
1.10      harris41   79: #   (9,"Error. The user name specified has invalid characters."),
                     80: #   (10,"Error. A password entry had an invalid character.") )
1.4       harris41   81: 
1.12      harris41   82: # ------------------------------------------------------------- Initializations
1.1       harris41   83: # Security
1.12      harris41   84: $ENV{'PATH'}='/bin:/usr/bin:/usr/local/sbin:/home/httpd/perl'; # Nullify path
                     85:                                                                # information
1.13      harris41   86: delete @ENV{qw(IFS CDPATH ENV BASH_ENV)}; # nullify potential taints
1.1       harris41   87: 
1.12      harris41   88: # Do not print error messages
                     89: my $noprint=1;
                     90: 
1.18      foxr       91: print "In lcpasswd" unless $noprint;
                     92: 
1.12      harris41   93: # ----------------------------- Make sure this process is running from user=www
                     94: my $wwwid=getpwnam('www');
                     95: &disable_root_capability;
                     96: if ($wwwid!=$>) {
                     97:     print("User ID mismatch.  This program must be run as user 'www'\n")
                     98: 	unless $noprint;
1.4       harris41   99:     exit 1;
1.1       harris41  100: }
1.12      harris41  101: 
                    102: # ----------------------------------- Start running script with www permissions
1.2       harris41  103: &disable_root_capability;
1.1       harris41  104: 
1.12      harris41  105: # --------------------------- Handle case of another lcpasswd process (locking)
1.6       harris41  106: unless (&try_to_lock('/tmp/lock_lcpasswd')) {
1.12      harris41  107:     print "Error. Too many other simultaneous password change requests being ".
                    108: 	"made.\n" unless $noprint;
1.5       harris41  109:     exit 4;
                    110: }
                    111: 
1.12      harris41  112: # ------- Error-check input, need 3 values (user name, password 1, password 2).
1.4       harris41  113: my @input;
1.12      harris41  114: @input=<>;
                    115: if (@input!=3) {
                    116:     print("Error. Three lines need to be entered into standard input.\n")
                    117: 	unless $noprint;
1.6       harris41  118:     unlink('/tmp/lock_lcpasswd');
1.12      harris41  119:     exit 3;
1.1       harris41  120: }
1.14      harris41  121: foreach (@input) {chomp;}
1.1       harris41  122: 
1.12      harris41  123: my ($username,$password1,$password2)=@input;
1.8       harris41  124: $username=~/^(\w+)$/;
                    125: my $safeusername=$1;
1.12      harris41  126: if (($username ne $safeusername) or ($safeusername!~/^[A-Za-z]/)) {
1.8       harris41  127:     print "Error. The user name specified has invalid characters.\n";
                    128:     unlink('/tmp/lock_lcpasswd');
                    129:     exit 9;
                    130: }
1.9       harris41  131: my $pbad=0;
1.15      matthew   132: foreach (split(//,$password1)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}}
                    133: foreach (split(//,$password2)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}}
1.9       harris41  134: if ($pbad) {
                    135:     print "Error. A password entry had an invalid character.\n";
                    136:     unlink('/tmp/lock_lcpasswd');
                    137:     exit 10;
                    138: }
1.1       harris41  139: 
1.12      harris41  140: # -- Only add user if the two password arguments match.
                    141: if ($password1 ne $password2) {
                    142:     print "Error. Password mismatch.\n" unless $noprint;
                    143:     unlink('/tmp/lock_lcpasswd');
                    144:     exit 13;
1.1       harris41  145: }
                    146: 
                    147: # Verify existence of user
1.12      harris41  148: unless(getpwnam($safeusername)) {
1.4       harris41  149:     print "Error. User $username does not exist.\n" unless $noprint;
1.6       harris41  150:     unlink('/tmp/lock_lcpasswd');
1.4       harris41  151:     exit 5;
1.1       harris41  152: }
1.12      harris41  153: &enable_root_capability;
                    154: ($>,$<)=(0,0);
1.18      foxr      155: 
                    156: print "Now $> , $< , -invoking pwchange with $safeusername $password1"
1.17      foxr      157:     unless $noprint;
1.12      harris41  158: open OUT,"|pwchange $safeusername";
                    159: print OUT $password1;
                    160: print OUT "\n";
                    161: close OUT;
1.20      albertel  162: ($>,$<)=(0,$wwwid);
1.12      harris41  163: 
1.20      albertel  164: print "pwchange done, back to uid $wwwid" unless $noprint;
1.17      foxr      165: 
1.12      harris41  166: if ($?) {
                    167:     exit 8;
1.1       harris41  168: }
1.12      harris41  169: my $userid=getpwnam($safeusername);
                    170: 
1.13      harris41  171: if (-e '/usr/bin/smbpasswd') {
1.12      harris41  172: 
                    173:     ($>,$<)=(0,0); # fool smbpasswd here to think this is not a setuid
                    174:                    # environment
1.1       harris41  175: 
1.21    ! albertel  176: #   If the -a switch is put on the smbpasswd
1.17      foxr      177: # command line, either a new entry will be created or the old one
                    178: # will be used. 
                    179: # Therefore the old strategy of looking for and adding a dummy entry is 
                    180: # not needed... Finally, the smbpasswd file is in /etc/samba not 
                    181: # /etc/smbpasswd as older versions of the script implied.
                    182: 
                    183:     print "Running smbpasswd" unless $noprint;
                    184:     open(OUT,"|/usr/bin/smbpasswd -s -a $safeusername>/dev/null") or
1.13      harris41  185: 	die('cannot run smbpasswd');
1.12      harris41  186:     print OUT $password2; print OUT "\n";
                    187:     print OUT $password2; print OUT "\n";
1.2       harris41  188:     close OUT;
1.12      harris41  189:     $<=$wwwid; # unfool the program
1.17      foxr      190:     print "smbpasswd done" unless $noprint;
1.2       harris41  191: }
1.12      harris41  192: 
1.1       harris41  193: &disable_root_capability;
1.6       harris41  194: unlink('/tmp/lock_lcpasswd');
1.4       harris41  195: exit 0;
1.1       harris41  196: 
1.12      harris41  197: # ---------------------------------------------- have setuid script run as root
1.1       harris41  198: sub enable_root_capability {
1.2       harris41  199:     if ($wwwid==$>) {
1.18      foxr      200: 	($<,$>)=($>,0);
                    201: 	($(,$))=($),0);
1.1       harris41  202:     }
                    203:     else {
                    204: 	# root capability is already enabled
                    205:     }
1.2       harris41  206:     return $>;
1.1       harris41  207: }
                    208: 
1.12      harris41  209: # ----------------------------------------------- have setuid script run as www
1.1       harris41  210: sub disable_root_capability {
1.2       harris41  211:     if ($wwwid==$<) {
1.1       harris41  212: 	($<,$>)=($>,$<);
                    213: 	($(,$))=($),$();
                    214:     }
                    215:     else {
                    216: 	# root capability is already disabled
                    217:     }
                    218: }
                    219: 
1.12      harris41  220: # ----------------------- make sure that another lcpasswd process isn't running
1.1       harris41  221: sub try_to_lock {
                    222:     my ($lockfile)=@_;
                    223:     my $currentpid;
                    224:     my $lastpid;
1.5       harris41  225:     # Do not manipulate lock file as root
                    226:     if ($>==0) {
                    227: 	return 0;
                    228:     }
                    229:     # Try to generate lock file.
                    230:     # Wait 3 seconds.  If same process id is in
                    231:     # lock file, then assume lock file is stale, and
                    232:     # go ahead.  If process id's fluctuate, try
                    233:     # for a maximum of 10 times.
1.1       harris41  234:     for (0..10) {
                    235: 	if (-e $lockfile) {
                    236: 	    open(LOCK,"<$lockfile");
                    237: 	    $currentpid=<LOCK>;
                    238: 	    close LOCK;
                    239: 	    if ($currentpid==$lastpid) {
                    240: 		last;
                    241: 	    }
                    242: 	    sleep 3;
                    243: 	    $lastpid=$currentpid;
                    244: 	}
                    245: 	else {
                    246: 	    last;
                    247: 	}
                    248: 	if ($_==10) {
                    249: 	    return 0;
                    250: 	}
                    251:     }
                    252:     open(LOCK,">$lockfile");
                    253:     print LOCK $$;
                    254:     close LOCK;
                    255:     return 1;
                    256: }
1.13      harris41  257: 
                    258: =head1 NAME
                    259: 
                    260: lcpasswd - LON-CAPA setuid script to synchronously change all
                    261:            filesystem-related passwords (samba, unix, etc)
                    262: 
                    263: =head1 DESCRIPTION
                    264: 
                    265: LON-CAPA setuid script to synchronously change all
                    266: filesystem-related passwords (samba, unix, etc)
                    267: 
                    268: =head1 README
                    269: 
                    270: LON-CAPA setuid script to synchronously change all
                    271: filesystem-related passwords (samba, unix, etc)
                    272: 
                    273: =head1 PREREQUISITES
                    274: 
                    275: =head1 COREQUISITES
                    276: 
                    277: =pod OSNAMES
                    278: 
                    279: linux
                    280: 
                    281: =pod SCRIPT CATEGORIES
                    282: 
                    283: LONCAPA/Administrative
                    284: 
                    285: =cut

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