--- loncom/Attic/lcuseradd 2004/09/02 19:04:53 1.25.2.2 +++ loncom/Attic/lcuseradd 2005/06/21 10:58:38 1.37 @@ -5,16 +5,8 @@ # lcuseradd - LON-CAPA setuid script to coordinate all actions # with adding a user with filesystem privileges (e.g. author) # -# YEAR=2002 -# May 19, 2002 Ron Fox -# - Removed creation of the pulic_html directory. This directory -# can now be added in two ways: -# o The user can add it themselves if they want some local web -# space which may or may not contain construction items. -# o LonCapa will add it if/when the user is granted an Author -# role. # -# $Id: lcuseradd,v 1.25.2.2 2004/09/02 19:04:53 albertel Exp $ +# $Id: lcuseradd,v 1.37 2005/06/21 10:58:38 foxr Exp $ ### ############################################################################### @@ -40,6 +32,8 @@ ############################################################################### use strict; +use File::Find; + # ------------------------------------------------------- Description of script # @@ -50,11 +44,20 @@ use strict; # www becomes a member of this user group. # -------------- Invoking script (standard input versus command-line arguments) +# Otherwise sensitive information will be available to ps-ers for +# a small but exploitable time window. # # Standard input (STDIN) usage # First line is USERNAME # Second line is PASSWORD # Third line is PASSWORD +# Fouth line is the name of a file to which an error code will be written. +# If the fourth line is omitted, no error file will be written. +# In either case, the program Exits with the code as its Exit status. +# The error file will just be a single line containing an +# error code. +# +# # # Command-line arguments [USERNAME] [PASSWORD] [PASSWORD] # Yes, but be very careful here (don't pass shell commands) @@ -78,9 +81,9 @@ use strict; # ---------------------------------- Example usage inside another piece of code # Usage within code # -# $exitcode= +# $Exitcode= # system("/home/httpd/perl/lcuseradd","NAME","PASSWORD1","PASSWORD2")/256; -# print "uh-oh" if $exitcode; +# print "uh-oh" if $Exitcode; # ---------------------------------------------------- Description of functions # enable_root_capability() : have setuid script run as root @@ -88,7 +91,7 @@ use strict; # try_to_lock() : make sure that another lcpasswd process isn't running # ------------------------------------------------------------------ Exit codes -# These are the exit codes. +# These are the Exit codes. # ( (0,"ok"), # (1,"User ID mismatch. This program must be run as user 'www'"), # (2,"Error. This program needs 3 command-line arguments (username, ". @@ -106,6 +109,7 @@ use strict; # (12,"Error. Something went wrong with the addition of user ". # "\"$safeusername\"."), # (13,"Error. Password mismatch."), +# (14, "Error filename is invalid") # ------------------------------------------------------------- Initializations # Security @@ -116,6 +120,10 @@ delete @ENV{qw(IFS CDPATH ENV BASH_ENV)} # Do not print error messages. my $noprint=1; +# Error file: + +my $error_file; # This is either the error file name or undef. + print "In lcuseradd\n" unless $noprint; # ----------------------------- Make sure this process is running from user=www @@ -124,7 +132,7 @@ my $wwwid=getpwnam('www'); if ($wwwid!=$>) { print("User ID mismatch. This program must be run as user 'www'\n") unless $noprint; - exit 1; + &Exit(1); } # ----------------------------------- Start running script with www permissions @@ -134,32 +142,30 @@ if ($wwwid!=$>) { unless (&try_to_lock("/tmp/lock_lcpasswd")) { print "Error. Too many other simultaneous password change requests being ". "made.\n" unless $noprint; - exit 4; + &Exit(4); } # ------- Error-check input, need 3 values (user name, password 1, password 2). my @input; -if (@ARGV==3) { +if (@ARGV>=3) { @input=@ARGV; -} -elsif (@ARGV) { - print("Error. This program needs 3 command-line arguments (username, ". - "password 1, password 2).\n") unless $noprint; +} elsif (@ARGV) { + print("Error. This program needs at least 3 command-line arguments (username, ". + "password 1, password 2 [errorfile]).\n") unless $noprint; unlink('/tmp/lock_lcpasswd'); - exit 2; -} -else { + &Exit(2); +} else { @input=<>; - if (@input!=3) { - print("Error. Three lines should be entered into standard input.\n") + if (@input < 3) { + print("Error. At least three lines should be entered into standard input.\n") unless $noprint; unlink('/tmp/lock_lcpasswd'); - exit 3; + &Exit(3); } foreach (@input) {chomp;} } -my ($username,$password1,$password2)=@input; +my ($username,$password1,$password2, $error_file)=@input; print "Username = ".$username."\n" unless $noprint; $username=~/^(\w+)$/; print "Username after substitution - ".$username unless $noprint; @@ -170,30 +176,66 @@ if (($username ne $safeusername) or ($sa print "Error. The user name specified $username $safeusername has invalid characters.\n" unless $noprint; unlink('/tmp/lock_lcpasswd'); - exit 9; + &Exit(9); } my $pbad=0; foreach (split(//,$password1)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}} foreach (split(//,$password2)) {if ((ord($_)<32)||(ord($_)>126)){$pbad=1;}} if ($pbad) { - print "Error. A password entry had an invalid character.\n"; + print "Error. A password entry had an invalid character.\n" unless $noprint; unlink('/tmp/lock_lcpasswd'); - exit 10; + &Exit(10); +} + +# +# Safe the filename. For our case, it must only have alpha, numeric, period +# and path sparators.. +# + +print "Error file is $error_file \n" unless $noprint; + +if($error_file) { + if($error_file =~ /^([(\w)(\d)\.\/]+)$/) { + print "Error file matched pattern $error_file : $1\n" unless $noprint; + my $safe_error_file = $1; # Untainted I think. + print "Error file after transform $safe_error_file\n" + unless $noprint; + if($error_file == $safe_error_file) { + $error_file = $safe_error_file; # untainted error_file. + } else { + $error_file =""; + print "Invalid error filename\n" unless $noprint; + Exit(14); + } + + } else { + $error_file=""; + print "Invalid error filename\n" unless $noprint; + Exit(14); + } } -# -- Only add user if we can create a brand new home directory (/home/username) -if (-e "/home/$safeusername") { - print "Error. User already exists.\n" unless $noprint; + +# -- Only add the user if they are >not< in /etc/passwd. +# Used to look for the ability to create a new directory for the +# user, however that disallows authentication changes from i +# internal->fs.. so just check the passwd file instead. +# +my $not_found = system("cut -d: -f1 /etc/passwd | grep -q \"^$safeusername\$\" "); +if (!$not_found) { + print "Error user already exists\n" unless $noprint; unlink('/tmp/lock_lcpasswd'); - exit 11; + &Exit(11); } + + # -- Only add user if the two password arguments match. if ($password1 ne $password2) { print "Error. Password mismatch.\n" unless $noprint; unlink('/tmp/lock_lcpasswd'); - exit 13; + &Exit(13); } print "enabling root\n" unless $noprint; # ---------------------------------- Start running script with root permissions @@ -207,13 +249,39 @@ my $status = system('/usr/sbin/useradd', if ($status) { print "Error. Something went wrong with the addition of user ". "\"$safeusername\".\n" unless $noprint; - print "Final status of useradd = $status"; + print "Final status of useradd = $status\n"; + unlink('/tmp/lock_lcpasswd'); + &Exit(12); +} +my ($dmy1, $dmy2, $uid, $gid) = getpwnam($safeusername); +my ($group) = getgrgid($gid); +if (! $group) { + print "Error. The primary group of user \"$safeusername\" could not be". + "determined.\n" unless $noprint; + system("/usr/sbin/userdel -r $safeusername"); unlink('/tmp/lock_lcpasswd'); - exit 12; + &Exit(12); } +if ($group != $safeusername) { + $status = system("/usr/sbin/groupadd -g $uid $safeusername"); + if (! $status) { + $status = system("/usr/sbin/usermod -g $uid $safeusername"); + if ($status) { + system("/usr/sbin/groupdel $safeusername"); + } + } + if ($status) { + print "Error. Something went wrong with the addition of user ". + "\"$safeusername\".\n" unless $noprint; + system("/usr/sbin/userdel -r $safeusername"); + unlink('/tmp/lock_lcpasswd'); + &Exit(12); + } +} + print "Done adding user\n" unless $noprint; # Make www a member of that user group. -my $groups=`/usr/bin/groups www` or exit(6); +my $groups=`/usr/bin/groups www` or &Exit(6); # untaint my ($safegroups)=($groups=~/:\s*([\s\w]+)/); $groups=$safegroups; @@ -226,7 +294,7 @@ if (system('/usr/sbin/usermod','-G',$gl, print "Error. Could not make www a member of the group ". "\"$safeusername\".\n" unless $noprint; unlink('/tmp/lock_lcpasswd'); - exit 6; + &Exit(6); } # ---------------------------------------------------------------- Set password @@ -245,8 +313,8 @@ print OUT $password1; print OUT "\n"; close OUT; if ($?) { - print "abnormal exit from close lcpasswd\n" unless $noprint; - exit 8; + print "abnormal Exit from close lcpasswd\n" unless $noprint; + &Exit(8); } ($>,$<)=($wwwid,0); &enable_root_capability; @@ -260,7 +328,6 @@ if ($?) { system('/bin/chmod','-R','0660',"/home/$safeusername"); system('/bin/chmod','0710',"/home/$safeusername"); mkdir "/home/$safeusername/public_html",0755; -system('/bin/chmod','02770',"/home/$safeusername/public_html"); open OUT,">/home/$safeusername/public_html/index.html"; print OUT< @@ -275,31 +342,38 @@ print OUT<; close(PID); - my ($safepid)=($pid=~s/(\D+)//g); + my $pid=~ /(\D+)/; + my $safepid = $1; if ($pid) { system('kill','-USR1',"$safepid"); } } # -------------------------------------------------------- Exit script -print "lcuseradd exiting\n" unless $noprint; +print "lcuseradd Exiting\n" unless $noprint; &disable_root_capability; -exit 0; +&Exit(0); # ---------------------------------------------- Have setuid script run as root sub enable_root_capability { if ($wwwid==$>) { ($<,$>)=($>,0); ($(,$))=($),0); - } - else { + } else { # root capability is already enabled } return $>; @@ -310,8 +384,7 @@ sub disable_root_capability { if ($wwwid==$<) { ($<,$>)=($>,$<); ($(,$))=($),$(); - } - else { + } else { # root capability is already disabled } } @@ -340,8 +413,7 @@ sub try_to_lock { } sleep 3; $lastpid=$currentpid; - } - else { + } else { last; } if ($_==10) { @@ -353,6 +425,73 @@ sub try_to_lock { close LOCK; return 1; } +# Called by File::Find::find for each file examined. +# +# Untaint the file and, if it is a directory, +# chmod it to 02770 +# +sub set_permission { + $File::Find::name =~ /^(.*)$/; + my $safe_name = $1; # Untainted filename... + + print "$safe_name" unless $noprint; + if(-d $safe_name) { + print " - directory" unless $noprint; + chmod(02770, $safe_name); + } + print "\n" unless $noprint; + +} +# +# Set up the correct permissions for all files in the +# user's public htmldir. We just do a chmod -R 0660 ... for +# the ordinary files. The we use File::Find +# to pop through the directory tree changing directories only +# to 02770: +# +sub set_public_html_permissions { + my ($topdir) = @_; + + # Set the top level dir permissions (I'm not sure if find + # will enumerate it specifically), correctly and all + # files and dirs to the 'ordinary' file permissions: + + system("chmod -R 0660 $topdir"); + chmod(02770, $topdir); + + # Now use find to locate all directories under $topdir + # and set their modes to 02770... + # + print "Find file\n " unless $noprint; + File::Find::find({"untaint" => 1, + "untaint_pattern" => qr(/^(.*)$/), + "untaint_skip" => 1, + "no_chdir" => 1, + "wanted" => \&set_permission }, "$topdir"); + + +} + +#-------------------------- Exit... +# +# Write the file if the error_file is defined. Regardless +# Exit with the status code. +# +sub Exit { + my ($code) = @_; # Status code. + + # TODO: Ensure the error file is owned/deletable by www:www: + + &disable_root_capability(); # We run unprivileged to write the error file. + + print "Exiting with status $code error file is $error_file\n" unless $noprint; + if($error_file) { + open(FH, ">$error_file"); + print FH "$code\n"; + close(FH); + } + exit $code; +} =head1 NAME