--- loncom/Attic/lcuseradd	2000/10/29 22:20:43	1.3
+++ loncom/Attic/lcuseradd	2000/10/30 02:42:17	1.9
@@ -20,23 +20,287 @@ use strict;
 # Second line is PASSWORD
 # Third line is PASSWORD
 
+# Valid passwords must consist of the
+# ascii characters within the inclusive
+# range of 0x20 (32) to 0x7E (126).
+# These characters are:
+# SPACE and
+# !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNO
+# PQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~
+
+# Valid user names must consist of ascii
+# characters that are alphabetical characters
+# (A-Z,a-z), numeric (0-9), or the underscore
+# mark (_). (Essentially, the perl regex \w).
+
 # Command-line arguments [USERNAME] [PASSWORD] [PASSWORD]
 # Yes, but be very careful here (don't pass shell commands)
 # and this is only supported to allow perl-system calls.
 
+# Usage within code
+#
+# $exitcode=system("/home/httpd/perl/lcuseradd","NAME","PASSWORD1","PASSWORD2")/256;
+# print "uh-oh" if $exitcode;
+
+# These are the exit codes.
+
 # Security
 $ENV{'PATH'}=""; # Nullify path information.
 $ENV{'BASH_ENV'}=""; # Nullify shell environment information.
 
+# Do not print error messages if there are command-line arguments
+my $noprint=0;
+if (@ARGV) {
+    $noprint=1;
+}
+
+# Read in /etc/passwd, and make sure this process is running from user=www
+open (IN, "</etc/passwd");
+my @lines=<IN>;
+close IN;
+my $wwwid;
+for my $l (@lines) {
+    chop $l;
+    my @F=split(/\:/,$l);
+    if ($F[0] eq 'www') {$wwwid=$F[2];}
+}
+if ($wwwid!=$<) {
+    print("User ID mismatch.  This program must be run as user 'www'\n") unless $noprint;
+    exit 1;
+}
+&disable_root_capability;
+
+# Handle case of another lcpasswd process
+unless (&try_to_lock("/tmp/lock_lcpasswd")) {
+    print "Error. Too many other simultaneous password change requests being made.\n" unless $noprint;
+    exit 4;
+}
+
+# Gather input.  Should be 3 values (user name, password 1, password 2).
+my @input;
+if (@ARGV==3) {
+    @input=@ARGV;
+}
+elsif (@ARGV) {
+    print("Error. This program needs 3 command-line arguments (username, password 1, password 2).\n") unless $noprint;
+    unlink('/tmp/lock_lcpasswd');
+    exit 2;
+}
+else {
+    @input=<>;
+    if (@input!=3) {
+	print("Error. Three lines should be entered into standard input.\n") unless $noprint;
+	unlink('/tmp/lock_lcpasswd');
+	exit 3;
+    }
+    map {chop} @input;
+}
+
+my ($username,$password1,$password2)=@input;
+$username=~/^(\w+)$/;
+my $safeusername=$1;
+if ($username ne $safeusername) {
+    print "Error. The user name specified has invalid characters.\n";
+    unlink('/tmp/lock_lcpasswd');
+    exit 9;
+}
+my $pbad=0;
+map {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}} (split(//,$password1));
+map {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}} (split(//,$password2));
+if ($pbad) {
+    print "Error. A password entry had an invalid character.\n";
+    unlink('/tmp/lock_lcpasswd');
+    exit 10;
+}
+
+# Only add user if we can create a brand new home directory (/home/username).
+if (-e "/home/$safeusername") {
+    print "Error. User already exists.\n" unless $noprint;
+    unlink('/tmp/lock_lcpasswd');
+    exit 8;
+}
+
+# Only add user if the two password arguments match.
+if ($password1 ne $password2) {
+    print "Error. Password mismatch.\n" unless $noprint;
+    unlink('/tmp/lock_lcpasswd');
+    exit 7;
+}
+
+&enable_root_capability;
+
 # Add user entry to /etc/passwd and /etc/groups in such
 # a way that www is a member of the user-specific group
 
-# useradd [-c comment] [-d home_dir]
-#               [-e expire_date] [-f inactive_time]
-#               [-g initial_group] [-G group[,...]]
-#               [-m [-k skeleton_dir] | -M] [-p passwd]
-#               [-s shell] [-u uid [ -o]] [-n] [-r] login
-system('/usr/sbin/useradd','-c','LON-CAPA user','-G','www','junk');
+if (system('/usr/sbin/useradd','-c','LON-CAPA user',$safeusername)) {
+    print "Error.  Something went wrong with the addition of user \"$safeusername\".\n" unless $noprint;
+    unlink('/tmp/lock_lcpasswd');
+    exit 5;
+}
+
+# Make www a member of that user group.
+if (system('/usr/sbin/usermod','-G',$safeusername,'www')) {
+    print "Error. Could not make www a member of the group \"$safeusername\".\n" unless $noprint;
+    unlink('/tmp/lock_lcpasswd');
+    exit 6;
+}
+
+# Set password with lcpasswd-style algorithm (which creates smbpasswd entry).
+# I cannot place a direct shell call to lcpasswd since I have to allow
+# for crazy characters in the password, and the setuid environment of perl
+# requires me to make everything safe.
+
+# Grab the line corresponding to username
+open (IN, "</etc/passwd");
+@lines=<IN>;
+close IN;
+my ($userid,$useroldcryptpwd);
+my @F; my @U;
+for my $l (@lines) {
+    @F=split(/\:/,$l);
+    if ($F[0] eq $username) {($userid,$useroldcryptpwd)=($F[2],$F[1]); @U=@F;}
+}
+
+# Verify existence of user
+if (!defined($userid)) {
+    print "Error. User $username does not exist.\n" unless $noprint;
+    unlink('/tmp/lock_lcpasswd');
+    exit 5;
+}
+
+# Construct new password entry (random salt)
+my $newcryptpwd=crypt($newpwd,(join '', ('.', '/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]));
+$U[1]=$newcryptpwd;
+my $userline=join(':',@U);
+my $rootid=&enable_root_capability;
+if ($rootid!=0) {
+    print "Error.  Root was not successfully enabled.\n" unless $noprint;
+    unlink('/tmp/lock_lcpasswd');
+    exit 7;
+}
+open PASSWORDFILE, '>/etc/passwd' or (print("Error.  Cannot open /etc/passwd.\n") && unlink('/tmp/lock_lcpasswd') && exit(8));
+for my $l (@lines) {
+    @F=split(/\:/,$l);
+    if ($F[0] eq $username) {print PASSWORDFILE "$userline\n";}
+    else {print PASSWORDFILE "$l\n";}
+}
+close PASSWORDFILE;
+
+($>,$<)=(0,0); # fool smbpasswd here to think this is not a setuid environment
+unless (-e '/etc/smbpasswd') {
+    open (OUT,'>/etc/smbpasswd'); close OUT;
+}
+my $smbexist=0;
+open (IN, '</etc/smbpasswd');
+my @lines=<IN>;
+close IN;
+for my $l (@lines) {
+    chop $l;
+    my @F=split(/\:/,$l);
+    if ($F[0] eq $username) {$smbexist=1;}
+}
+unless ($smbexist) {
+    open(OUT,'>>/etc/smbpasswd');
+    print OUT join(':',($safeusername,$userid,'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX','','/home/'.$safeusername,'/bin/bash')) . "\n";
+    close OUT;
+}
+open(OUT,"|/usr/bin/smbpasswd -s $safeusername>/dev/null");
+print OUT $newpwd; print OUT "\n";
+print OUT $newpwd; print OUT "\n";
+close OUT;
+$<=$wwwid; # unfool the program
+
+# Make final modifications to the user directory.
+# Add a public_html file with a stand-in index.html file.
+
+system('/bin/chmod','-R','0640',"/home/$safeusername");
+system('/bin/chmod','0750',"/home/$safeusername");
+mkdir "/home/$safeusername/public_html",0750;
+open OUT,">/home/$safeusername/public_html";
+print OUT<<END;
+<HTML>
+<HEAD>
+<TITLE>$safeusername</TITLE>
+</HEAD>
+<BODY>
+<H1>$safeusername</H1>
+<P>
+Learning Online Network
+</P>
+<P>
+This area provides for:
+</P>
+<UL>
+<LI>resource construction
+<LI>resource publication
+<LI>record-keeping
+</UL>
+</BODY>
+</HTML>
+END
+close OUT;
+
+&disable_root_capability;
+unlink('/tmp/lock_lcpasswd');
+exit 0;
+
+# ----------------------------------------------------------- have setuid script run as root
+sub enable_root_capability {
+    if ($wwwid==$>) {
+	($<,$>)=($>,$<);
+	($(,$))=($),$();
+    }
+    else {
+	# root capability is already enabled
+    }
+    return $>;
+}
 
-# Set password with lcpasswd (which creates smbpasswd entry).
+# ----------------------------------------------------------- have setuid script run as www
+sub disable_root_capability {
+    if ($wwwid==$<) {
+	($<,$>)=($>,$<);
+	($(,$))=($),$();
+    }
+    else {
+	# root capability is already disabled
+    }
+}
 
+# ----------------------------------- make sure that another lcpasswd process isn't running
+sub try_to_lock {
+    my ($lockfile)=@_;
+    my $currentpid;
+    my $lastpid;
+    # Do not manipulate lock file as root
+    if ($>==0) {
+	return 0;
+    }
+    # Try to generate lock file.
+    # Wait 3 seconds.  If same process id is in
+    # lock file, then assume lock file is stale, and
+    # go ahead.  If process id's fluctuate, try
+    # for a maximum of 10 times.
+    for (0..10) {
+	if (-e $lockfile) {
+	    open(LOCK,"<$lockfile");
+	    $currentpid=<LOCK>;
+	    close LOCK;
+	    if ($currentpid==$lastpid) {
+		last;
+	    }
+	    sleep 3;
+	    $lastpid=$currentpid;
+	}
+	else {
+	    last;
+	}
+	if ($_==10) {
+	    return 0;
+	}
+    }
+    open(LOCK,">$lockfile");
+    print LOCK $$;
+    close LOCK;
+    return 1;
+}