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Annotation of loncom/lcuserdel, revision 1.3

1.1       harris41    1: #!/usr/bin/perl
                      2: #
                      3: # lcuserdel
                      4: #
                      5: # Scott Harrison
                      6: # October 27, 2000
1.3     ! harris41    7: # October 28, 2000
1.1       harris41    8: 
                      9: use strict;
                     10: 
1.2       harris41   11: # This script is a setuid script (chmod 6755) that should
1.1       harris41   12: # be run by user 'www'.  It DOES NOT delete directories.
                     13: # All it does is remove a user's entries from
                     14: # /etc/passwd, /etc/groups, and /etc/smbpasswd.
                     15: 
1.3     ! harris41   16: # This script works under the same process control mechanism
        !            17: # as lcuseradd and lcpasswd, to make sure that only one of these
        !            18: # processes is running at any one time on the system.
1.1       harris41   19: 
                     20: # Standard input usage
                     21: # First line is USERNAME
                     22: 
                     23: # Command-line arguments [USERNAME]
                     24: # Yes, but be very careful here (don't pass shell commands)
                     25: # and this is only supported to allow perl-system calls.
                     26: 
1.2       harris41   27: # Usage within code
                     28: #
1.3     ! harris41   29: # $exitcode=system("/home/httpd/perl/lcuserdel","NAME")/256;
1.2       harris41   30: # print "uh-oh" if $exitcode;
                     31: 
                     32: # These are the exit codes.
                     33: 
1.1       harris41   34: # Security
                     35: $ENV{'PATH'}=""; # Nullify path information.
                     36: $ENV{'BASH_ENV'}=""; # Nullify shell environment information.
1.2       harris41   37: 
                     38: # Do not print error messages if there are command-line arguments
                     39: my $noprint=0;
                     40: if (@ARGV) {
                     41:     $noprint=1;
                     42: }
                     43: 
1.3     ! harris41   44: # Read in /etc/passwd, and make sure this process is running from user=www
1.2       harris41   45: open (IN, "</etc/passwd");
                     46: my @lines=<IN>;
                     47: close IN;
                     48: my $wwwid;
                     49: for my $l (@lines) {
                     50:     chop $l;
                     51:     my @F=split(/\:/,$l);
                     52:     if ($F[0] eq 'www') {$wwwid=$F[2];}
                     53: }
                     54: if ($wwwid!=$<) {
                     55:     print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
                     56:     exit 1;
                     57: }
                     58: &disable_root_capability;
                     59: 
1.3     ! harris41   60: # Handle case of another lcpasswd process
        !            61: unless (&try_to_lock("/tmp/lock_lcpasswd")) {
        !            62:     print "Error. Too many other simultaneous password change requests being made.\n" unless $noprint;
        !            63:     exit 4;
        !            64: }
        !            65: 
        !            66: # Gather input.  Should only be 1 value (user name).
1.2       harris41   67: my @input;
1.3     ! harris41   68: if (@ARGV==1) {
1.2       harris41   69:     @input=@ARGV;
                     70: }
                     71: elsif (@ARGV) {
1.3     ! harris41   72:     print("Error. This program needs just 1 command-line argument (username).\n") unless $noprint;
1.2       harris41   73:     exit 2;
                     74: }
                     75: else {
                     76:     @input=<>;
1.3     ! harris41   77:     if (@input!=1) {
        !            78: 	print("Error. Only one line should be entered into standard input.\n") unless $noprint;
1.2       harris41   79: 	exit 3;
                     80:     }
                     81:     map {chop} @input;
                     82: }
1.3     ! harris41   83: 
        !            84: &disable_root_capability;
        !            85: unlink("/tmp/lock_lcpasswd");
        !            86: exit 0;
        !            87: 
        !            88: # ----------------------------------------------------------- have setuid script run as root
        !            89: sub enable_root_capability {
        !            90:     if ($wwwid==$>) {
        !            91: 	($<,$>)=($>,$<);
        !            92: 	($(,$))=($),$();
        !            93:     }
        !            94:     else {
        !            95: 	# root capability is already enabled
        !            96:     }
        !            97:     return $>;
        !            98: }
        !            99: 
        !           100: # ----------------------------------------------------------- have setuid script run as www
        !           101: sub disable_root_capability {
        !           102:     if ($wwwid==$<) {
        !           103: 	($<,$>)=($>,$<);
        !           104: 	($(,$))=($),$();
        !           105:     }
        !           106:     else {
        !           107: 	# root capability is already disabled
        !           108:     }
1.2       harris41  109: }
                    110: 
1.3     ! harris41  111: # ----------------------------------- make sure that another lcpasswd process isn't running
        !           112: sub try_to_lock {
        !           113:     my ($lockfile)=@_;
        !           114:     my $currentpid;
        !           115:     my $lastpid;
        !           116:     # Do not manipulate lock file as root
        !           117:     if ($>==0) {
        !           118: 	return 0;
        !           119:     }
        !           120:     # Try to generate lock file.
        !           121:     # Wait 3 seconds.  If same process id is in
        !           122:     # lock file, then assume lock file is stale, and
        !           123:     # go ahead.  If process id's fluctuate, try
        !           124:     # for a maximum of 10 times.
        !           125:     for (0..10) {
        !           126: 	if (-e $lockfile) {
        !           127: 	    open(LOCK,"<$lockfile");
        !           128: 	    $currentpid=<LOCK>;
        !           129: 	    close LOCK;
        !           130: 	    if ($currentpid==$lastpid) {
        !           131: 		last;
        !           132: 	    }
        !           133: 	    sleep 3;
        !           134: 	    $lastpid=$currentpid;
        !           135: 	}
        !           136: 	else {
        !           137: 	    last;
        !           138: 	}
        !           139: 	if ($_==10) {
        !           140: 	    return 0;
        !           141: 	}
        !           142:     }
        !           143:     open(LOCK,">$lockfile");
        !           144:     print LOCK $$;
        !           145:     close LOCK;
        !           146:     return 1;
        !           147: }
1.2       harris41  148: 
1.1       harris41  149: