--- loncom/Attic/lchtmldir 2002/04/27 12:01:50 1.1 +++ loncom/Attic/lchtmldir 2008/05/30 13:37:48 1.21 @@ -2,6 +2,8 @@ # The Learning Online Network with CAPA # +# $Id: lchtmldir,v 1.21 2008/05/30 13:37:48 raeburn Exp $ +# # Copyright Michigan State University Board of Trustees # # This file is part of the LearningOnline Network with CAPA (LON-CAPA). @@ -41,7 +43,7 @@ # NSCL # Michigan State University8 # East Lansing, MI 48824-1321 - +# # General flow of control: # 1. Validate process state (must be run as www). # 2. Validate parameters: Need two parameters: @@ -61,17 +63,23 @@ # - internal - www:www/2775 # - local - www:www/2775 # - +# # # Take a few precautions to be sure that we're not vulnerable to trojan # horses and other fine issues: # use strict; +use Fcntl qw(:mode); +use DirHandle; +use POSIX; +use lib '/home/httpd/lib/perl/'; +use LONCAPA qw(:match); $ENV{'PATH'} = '/bin:/usr/bin:/usr/local/sbin:/home/httpd/perl'; delete @ENV{qw{IFS CDPATH ENV BASH_ENV}}; -my $DEBUG = 0; # .nonzero -> Debug printing enabled. +my $DEBUG = 1; # .nonzero -> Debug printing enabled. +my $path_sep = "/"; # Unix like operating systems. # If the UID of the running process is not www exit with error. @@ -115,20 +123,20 @@ if($DEBUG) { } -if( $authentication ne "unix" && - $authentication ne "internal" && - $authentication ne "krb4" && - $authentication ne "localauth") { +if( $authentication ne "unix:" && + $authentication ne "internal:" && + $authentication !~ /^krb(4|5):(.*)/ && + $authentication ne "localauth:") { if($DEBUG) { print("Invalid authentication parameter: ".$authentication."\n"); - print("Should be one of: unix, internal, krb4, localauth\n"); + print("Should be one of-- unix: internal: krb4: krb5: localauth:\n"); } exit 3; } # Untaint the username. -my $match = $username =~ /^(\w+)$/; +my $match = $username =~ /^($match_username)$/; my $patt = $1; if($DEBUG) { @@ -140,7 +148,7 @@ my $safeuser = $patt; if($DEBUG) { print("Save username = $safeuser \n"); } -if(($username ne $safeuser) or ($safeuser!~/^[A-za-z]/)) { +if($username ne $safeuser) { if($DEBUG) { print("User name $username had illegal characters\n"); } @@ -150,36 +158,58 @@ if(($username ne $safeuser) or ($safeuse #untaint the base directory require that the dir contain only # alphas, / numbers or underscores, and end in /$safeuser -$dir =~ /(^([\w\/]+))/; -my $dirtry1 = $1; -$dir =~ /$\/$safeuser/; -my $dirtry2 = $1; +my ($allowed_dir) = ($dir =~ m{(^([/]|$match_username)+)}); -if(($dirtry1 ne $dir) or ($dirtry2 ne $dir)) { +my $has_correct_end = ($dir =~ m{/\Q$safeuser\E$}); + +if(($allowed_dir ne $dir) or (!$has_correct_end)) { if ($DEBUG) { print("Directory $dir is not a valid home for $safeuser\n"); } exit 5; } - # As root, create the directory. -my $fulldir = $dirtry1."/public_html"; +my $homedir = $allowed_dir; +my $fulldir = $homedir."/public_html"; + if($DEBUG) { print("Full directory path is: $fulldir \n"); } -if(!( -e $dirtry1)) { +if(!( -e $homedir)) { if($DEBUG) { - print("User's home directory $dirtry1 does not exist\n"); + print("User's home directory $homedir does not exist\n"); + } + if ($authentication eq "unix:") { + exit 6; + } +} +if ($authentication eq "unix:") { + # check whether group $safeuser exists. + my $usergroups = `id -nG $safeuser`; + if (! grep /^$safeuser$/, split(/\s+/,$usergroups)) { + if($DEBUG) { + print("Group \"$safeuser\" does not exist or $safeuser is not a member of that group.\n"); + } + exit 7; } - exit 6; } + + + &EnableRoot; -&System("/bin/mkdir $fulldir") unless (-e $fulldir); +# If authentication is internal and the top level directory exists +# give it the right permissions (in case this is a modification. + +if ($authentication eq "internal:") { + chmod(0711, $homedir); # so www can enter ~/public_html. +} + +&System("/bin/mkdir -p $fulldir") unless (-e $fulldir); unless(-e $fulldir."/index.html") { open OUT,">".$fulldir."/index.html"; print OUT< $safeuser - -

$safeuser

+ +

$safeuser Construction Space

+

+ The LearningOnline Network with Computer-Assisted Personalized Approach +

- Learning Online Network +This is your construction space within LON-CAPA, where you would construct resources which are meant to be +used across courses and institutions.

- This area provides for: +Material within this area can only be seen and edited by $safeuser and designated co-authors. To make +it available to students and other instructors, the material needs to be published.

- END close OUT; } -&System("/bin/chmod 02775 $fulldir"); -&System("/bin/chmod 0775 $fulldir"."/index.html"); - - -# Based on the authentiation mode, set the ownership of the directory. -if($authentication eq "unix") { # Unix mode authentication... - - - &System("/bin/chown -R $username".":".$username." ".$fulldir); - &JoinGroup($username); +&System("/bin/chmod 02770 $fulldir"); +&System("/bin/chmod 0770 $fulldir"."/index.html"); -} -elsif ($authentication eq "internal") { # Internal authentication. +# Based on the authentiation mode, set the ownership of the directory. - &System("/bin/chown -R www:www $fulldir"); -} -elsif ($authentication eq "krb4") { # Kerberos version 4 authentication - &System("/bin/chwon -R $username".':'.$username." ".$fulldir); - &JoinGroup($username); -} -elsif ($authentication eq "localauth") { # Local authentiation - &System("/bin/chown -R $username".':'.$username." $fulldir"); -} -else { - if($DEBUG) { - print("Authentication not legal".$authentication); +if($authentication eq "unix:") { # Unix mode authentication... + print "Unix auth\n"; + &System("/bin/chown -R $safeuser:$safeuser"." ".$fulldir); + &JoinGroup($safeuser); +} else { + # Internal, Kerberos, and Local authentication are for users + # who do not have unix accounts on the system. Therefore we + # will give ownership of their public_html directories to www:www + # If the user is an internal auth user, the rest of the directory tree + # gets owned by root. This chown is needed in case what's really happening + # is that a file system user is being demoted to internal user... + + if($authentication eq "internal:") { + # In case the user was a unix/filesystem authenticated user, + # we'll take a bit of time here to write a script in the + # user's home directory that can reset ownerships and permissions + # back the way the used to be. + + # This can take long enough for lond to time out, so we'll do it + # in a separate process that we'll not wait for. + # + my $fpid = fork; + if($fpid) { + &DisableRoot; + exit 0; + } else { + print "Forked\n"; + POSIX::setsid(); # Disassociate from parent. + print "Separate session\n"; + &write_restore_script($homedir); + print "Restore script written\n"; + &System("/bin/chown -R root:root ".$homedir); + &System("/bin/chown -R www:www ".$fulldir); + print "Exiting\n"; + exit 0; + } + } else { + &System("/bin/chown -R www:www ".$fulldir); } - &DisableRoot; - exit 5; } &DisableRoot; @@ -261,7 +306,7 @@ sub EnableRoot { # root capability is already enabled } if($DEBUG) { - print("Enable Root - id = $> \n"); + print("Enable Root - id = $> $<\n"); } return $>; } @@ -278,11 +323,17 @@ sub DisableRoot { print("Disable root: id = ".$>."\n"); } } - +# +# Join the www user to the user's group. +# we must be running with euid as root at this time. +# sub JoinGroup { my $usergroup = shift; my $groups = `/usr/bin/groups www`; + # untaint + my ($safegroups)=($groups=~/:\s+([\s\w]+)/); + $groups=$safegroups; chomp $groups; $groups=~s/^\S+\s+\:\s+//; my @grouplist=split(/\s+/,$groups); my @ugrouplist=grep {!/www|$usergroup/} @grouplist; @@ -294,17 +345,157 @@ sub JoinGroup { } exit 6; } - + if (-e '/var/run/httpd.pid') { + open(PID,'/var/run/httpd.pid'); + my $pid=; + close(PID); + my ($safepid) = $pid=~ /(\d+)/; + $pid = $safepid; + if ($pid) { + my $status = system("kill -USR1 $safepid"); + } + } } sub System { - my $command = shift; + my ($command,@args) = @_; if($DEBUG) { - print("system: $command \n"); + print("system: $command with args ".join(' ',@args)."\n"); + } + system($command,@args); +} + + + + + +# +# This file contains code to recursively process +# a Directory. This is a bit more powerful +# than File::Find in that we pass the full +# stat info to the processing function. +# For each file in the specified directory subtree, +# The user's Code reference is invoked for all files, regular and otherwise +# except: +# ., .. +# +# Parameters: +# code_ref - Code reference, invoked for each file in the tree. +# as follows: CodeRef(directory, name, statinfo) +# directory the path to the directory holding the file. +# name the name of the file within Directory. +# statinfo a reference to the stat of the file. +# start_dir - The starting point of the directory walk. +# +# NOTE: +# Yes, we could have just used File::Find, but since we have to get the +# stat anyway, this is actually simpler, as File::Find would have gotten +# the stat to figure out the file type and then we would have gotten it +# again. +# + +sub process_tree { + my ($code_ref, $start_dir) = @_; + + my $dir = new DirHandle $start_dir; + if (!defined($dir)) { + print "Failed to open dirhandle: $start_dir\n"; + } + + # Now iterate through this level of the tree: + + while (defined (my $name = $dir->read)) { + next if $name =~/^\.\.?$/; # Skip ., .. (see cookbook pg 319) + + my $full_name = $start_dir.$path_sep.$name; # Full filename path. + my @stat_info = lstat($full_name); + my $mode = $stat_info[2]; + my $type = $mode & 0170000; # File type. + + # Unless the file type is a symlink, call the user code: + + unless ($type == S_IFLNK) { + &$code_ref($start_dir, $name, \@stat_info); + } + + # If the entry is a directory, we need to recurse: + + + if (($type == S_IFDIR) != 0) { + &process_tree($code_ref, $full_name); + } } - system($command); + +} +# +# Callback from process_tree to write the script lines +# requried to restore files to current ownership and permission. +# Parameters: +# dir - Name of the directory the file lives in. +# name - Name of the file itself. +# statinfo - Array from lstat called on the file. +# +# +sub write_script { + my ($dir, $name, $statinfo) = @_; + + my $fullname = $dir.$path_sep.$name; + + # We're going to '' the name, but we need to deal with embedded + # ' characters. Using " is much worse as we'd then have to + # escape all the shell escapes too. This way all we need + # to do is replace ' with '\'' + + $fullname =~ s/\'/\'\\\'\'/g; + + my $perms = $statinfo->[2] & 0777; # Just permissions. + printf CHMODSCRIPT "chmod 0%o '%s'\n", $perms, $fullname; + printf CHMODSCRIPT "chown %d:%d '%s'\n", $statinfo->[4], $statinfo->[5], + $fullname + + +} +# +# Write a script in the user's home directory that can restore +# the permissions and ownerhips of all the files in the directory +# tree to their current ownerships and permissions. This is done +# prior to making the user into an internally authenticated user +# in case they were previously file system authenticated and +# need to go back. +# The file we will create will be of the form +# restore_n.sh Where n is a number that we will keep +# incrementing as needed until there isn't a file by that name. +# +# Parameters: +# dir - Path to the user's home directory. +# +sub write_restore_script { + my ($dir) = @_; + + # Create a unique file: + + my $version_number = 0; + my $filename = 'restore_'.$version_number.'.sh'; + my $full_name = $dir.$path_sep.$filename; + + while(-e $full_name) { + $version_number++; + $filename = 'restore_'.$version_number.'.sh'; + $full_name = $dir.$path_sep.$filename; + } + # $full_name is the full path of a file that does not yet exist + # of the form we want: + + open(CHMODSCRIPT, "> $full_name"); + + &process_tree(\&write_script, $dir); + + close(CHMODSCRIPT); + + chmod(0750, $full_name); + }