Annotation of loncom/lcpasswd, revision 1.7

1.1       harris41    1: #!/usr/bin/perl
1.3       harris41    2: #
                      3: # lcpasswd
                      4: #
                      5: # Scott Harrison
1.6       harris41    6: # SH: October 27, 2000
                      7: # SH: October 28, 2000
1.1       harris41    8: 
                      9: use strict;
                     10: 
                     11: # This script is a setuid script that should
1.4       harris41   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.
1.1       harris41   16: 
1.5       harris41   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: 
1.1       harris41   21: # Standard input usage
                     22: # First line is USERNAME
                     23: # Second line is CURRENT PASSWORD
                     24: # Third line is NEW PASSWORD
                     25: 
1.4       harris41   26: # Command-line arguments
                     27: # Yes, but be very careful here (don't pass shell commands)
                     28: # and this is only supported to allow perl-system calls.
                     29: 
                     30: # Usage within code
1.5       harris41   31: # Note: NEVER run as system("/home/httpd/perl/lcpasswd NAME OLDPWD NEWPWD")
1.4       harris41   32: #
1.5       harris41   33: # $exitcode=system("/home/httpd/perl/lcpasswd","NAME","OLDPWD","NEWPWD")/256;
1.4       harris41   34: # print "uh-oh" if $exitcode;
                     35: 
                     36: # These are the exit codes.
                     37: # ( (0,"ok"),
1.7     ! harris41   38: #   (1,"User ID mismatch.  This program must be run as user 'www'"),
1.4       harris41   39: #   (2,"Error. This program does not accept command-line arguments."),
1.6       harris41   40: #   (3,"Error. Three lines need to be entered into standard input."),
                     41: #   (4,"Error. Too many other simultaneous password change requests being made."),
                     42: #   (5,"Error. User $username does not exist."),
                     43: #   (6,"Error. Invalid entry of current password."),
1.7     ! harris41   44: #   (7,"Error.  Root was not successfully enabled."),
1.6       harris41   45: #   (8,"Error.  Cannot open /etc/passwd.") )
1.4       harris41   46: 
1.1       harris41   47: # Security
1.6       harris41   48: $ENV{'PATH'}='/bin:/usr/bin'; # Nullify path information except for what smbpasswd needs
                     49: $ENV{'BASH_ENV'}=''; # Nullify shell environment information.
1.1       harris41   50: 
1.4       harris41   51: # Do not print error messages if there are command-line arguments
                     52: my $noprint=0;
                     53: if (@ARGV) {
                     54:     $noprint=1;
                     55: }
                     56: 
1.5       harris41   57: # Read in /etc/passwd, and make sure this process is running from user=www
1.6       harris41   58: open (IN, '</etc/passwd');
1.1       harris41   59: my @lines=<IN>;
                     60: close IN;
                     61: my $wwwid;
                     62: for my $l (@lines) {
                     63:     chop $l;
                     64:     my @F=split(/\:/,$l);
                     65:     if ($F[0] eq 'www') {$wwwid=$F[2];}
                     66: }
                     67: if ($wwwid!=$<) {
1.4       harris41   68:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
                     69:     exit 1;
1.1       harris41   70: }
1.2       harris41   71: &disable_root_capability;
1.1       harris41   72: 
1.5       harris41   73: # Handle case of another lcpasswd process
1.6       harris41   74: unless (&try_to_lock('/tmp/lock_lcpasswd')) {
1.5       harris41   75:     print "Error. Too many other simultaneous password change requests being made.\n" unless $noprint;
                     76:     exit 4;
                     77: }
                     78: 
1.4       harris41   79: # Gather input.  Should only be 3 values.
                     80: my @input;
                     81: if (@ARGV==3) {
                     82:     @input=@ARGV;
                     83: }
                     84: elsif (@ARGV) {
                     85:     print("Error. This program needs 3 command-line arguments (username, old password, new password).\n") unless $noprint;
1.6       harris41   86:     unlink('/tmp/lock_lcpasswd');
1.4       harris41   87:     exit 2;
                     88: }
                     89: else {
                     90:     @input=<>;
                     91:     if (@input!=3) {
                     92: 	print("Error. Three lines need to be entered into standard input.\n") unless $noprint;
1.6       harris41   93: 	unlink('/tmp/lock_lcpasswd');
1.4       harris41   94: 	exit 3;
                     95:     }
                     96:     map {chop} @input;
1.1       harris41   97: }
                     98: 
1.4       harris41   99: my ($username,$oldpwd,$newpwd)=@input;
1.1       harris41  100: 
                    101: # Grab the line corresponding to username
                    102: my ($userid,$useroldcryptpwd);
                    103: my @F; my @U;
                    104: for my $l (@lines) {
                    105:     @F=split(/\:/,$l);
                    106:     if ($F[0] eq $username) {($userid,$useroldcryptpwd)=($F[2],$F[1]); @U=@F;}
                    107: }
                    108: 
                    109: # Verify existence of user
                    110: if (!defined($userid)) {
1.4       harris41  111:     print "Error. User $username does not exist.\n" unless $noprint;
1.6       harris41  112:     unlink('/tmp/lock_lcpasswd');
1.4       harris41  113:     exit 5;
1.1       harris41  114: }
                    115: 
                    116: # Verify password entry
                    117: if (crypt($oldpwd,$useroldcryptpwd) ne $useroldcryptpwd) {
1.4       harris41  118:     print "Error. Invalid entry of current password.\n" unless $noprint;
1.6       harris41  119:     unlink('/tmp/lock_lcpasswd');
1.4       harris41  120:     exit 6;
1.1       harris41  121: }
                    122: 
1.2       harris41  123: # Construct new password entry (random salt)
                    124: my $newcryptpwd=crypt($newpwd,(join '', ('.', '/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]));
1.1       harris41  125: $U[1]=$newcryptpwd;
1.6       harris41  126: my $userline=join(':',@U);
1.2       harris41  127: my $rootid=&enable_root_capability;
                    128: if ($rootid!=0) {
1.4       harris41  129:     print "Error.  Root was not successfully enabled.\n" unless $noprint;
1.6       harris41  130:     unlink('/tmp/lock_lcpasswd');
1.4       harris41  131:     exit 7;
1.2       harris41  132: }
1.6       harris41  133: open PASSWORDFILE, '>/etc/passwd' or (print("Error.  Cannot open /etc/passwd.\n") && unlink('/tmp/lock_lcpasswd') && exit(8));
1.1       harris41  134: for my $l (@lines) {
                    135:     @F=split(/\:/,$l);
                    136:     if ($F[0] eq $username) {print PASSWORDFILE "$userline\n";}
                    137:     else {print PASSWORDFILE "$l\n";}
                    138: }
                    139: close PASSWORDFILE;
1.2       harris41  140: $username=~/^(\w+)$/;
                    141: my $safeusername=$1;
                    142: ($>,$<)=(0,0); # fool smbpasswd here to think this is not a setuid environment
1.6       harris41  143: unless (-e '/etc/smbpasswd') {
                    144:     open (OUT,'>/etc/smbpasswd'); close OUT;
1.2       harris41  145: }
                    146: my $smbexist=0;
1.6       harris41  147: open (IN, '</etc/smbpasswd');
1.2       harris41  148: my @lines=<IN>;
                    149: close IN;
                    150: for my $l (@lines) {
                    151:     chop $l;
                    152:     my @F=split(/\:/,$l);
                    153:     if ($F[0] eq $username) {$smbexist=1;}
                    154: }
                    155: unless ($smbexist) {
1.6       harris41  156:     open(OUT,'>>/etc/smbpasswd');
                    157:     print OUT join(':',($safeusername,$userid,'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX','','/home/'.$safeusername,'/bin/bash')) . "\n";
1.2       harris41  158:     close OUT;
                    159: }
                    160: open(OUT,"|/usr/bin/smbpasswd -s $safeusername>/dev/null");
                    161: print OUT $newpwd; print OUT "\n";
                    162: print OUT $newpwd; print OUT "\n";
                    163: close OUT;
                    164: $<=$wwwid; # unfool the program
1.1       harris41  165: &disable_root_capability;
1.6       harris41  166: unlink('/tmp/lock_lcpasswd');
1.4       harris41  167: exit 0;
1.1       harris41  168: 
1.4       harris41  169: # ----------------------------------------------------------- have setuid script run as root
1.1       harris41  170: sub enable_root_capability {
1.2       harris41  171:     if ($wwwid==$>) {
1.1       harris41  172: 	($<,$>)=($>,$<);
                    173: 	($(,$))=($),$();
                    174:     }
                    175:     else {
                    176: 	# root capability is already enabled
                    177:     }
1.2       harris41  178:     return $>;
1.1       harris41  179: }
                    180: 
1.4       harris41  181: # ----------------------------------------------------------- have setuid script run as www
1.1       harris41  182: sub disable_root_capability {
1.2       harris41  183:     if ($wwwid==$<) {
1.1       harris41  184: 	($<,$>)=($>,$<);
                    185: 	($(,$))=($),$();
                    186:     }
                    187:     else {
                    188: 	# root capability is already disabled
                    189:     }
                    190: }
                    191: 
1.4       harris41  192: # ----------------------------------- make sure that another lcpasswd process isn't running
1.1       harris41  193: sub try_to_lock {
                    194:     my ($lockfile)=@_;
                    195:     my $currentpid;
                    196:     my $lastpid;
1.5       harris41  197:     # Do not manipulate lock file as root
                    198:     if ($>==0) {
                    199: 	return 0;
                    200:     }
                    201:     # Try to generate lock file.
                    202:     # Wait 3 seconds.  If same process id is in
                    203:     # lock file, then assume lock file is stale, and
                    204:     # go ahead.  If process id's fluctuate, try
                    205:     # for a maximum of 10 times.
1.1       harris41  206:     for (0..10) {
                    207: 	if (-e $lockfile) {
                    208: 	    open(LOCK,"<$lockfile");
                    209: 	    $currentpid=<LOCK>;
                    210: 	    close LOCK;
                    211: 	    if ($currentpid==$lastpid) {
                    212: 		last;
                    213: 	    }
                    214: 	    sleep 3;
                    215: 	    $lastpid=$currentpid;
                    216: 	}
                    217: 	else {
                    218: 	    last;
                    219: 	}
                    220: 	if ($_==10) {
                    221: 	    return 0;
                    222: 	}
                    223:     }
                    224:     open(LOCK,">$lockfile");
                    225:     print LOCK $$;
                    226:     close LOCK;
                    227:     return 1;
                    228: }

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