--- loncom/lcinstallfile	2009/02/20 11:26:34	1.1
+++ loncom/lcinstallfile	2010/10/12 10:14:25	1.5
@@ -1,6 +1,8 @@
 #!/usr/bin/perl
 #
-## Copyright Michigan State University Board of Trustees
+# Copyright Michigan State University Board of Trustees
+#
+# $Id: lcinstallfile,v 1.5 2010/10/12 10:14:25 foxr Exp $
 #
 # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
 #
@@ -22,10 +24,9 @@
 #
 #
 #
-# 2/17/2009 - Ron FOx
-# 
-
-http://www.lon-capa.org/
+# 2/17/2009 - Ron Fox
+#
+# http://www.lon-capa.org/
 #
 #  This file is a setuid script that allows lond or other www programs to install
 #  a file in the lon capa table directory.
@@ -41,12 +42,13 @@ http://www.lon-capa.org/
 
 use strict;
 
-my $LONCAPAHOME = '/home/httpd;	     # Adjust if loncapa isn't installed here.
-
-use lib "$LONCAPAHOME/perl/lib";
+use lib "/home/httpd/lib/perl";     # Adjust if loncapa lib isn't installed here.
 use LONCAPA;
 use LONCAPA::Configuration;
 use IO::File;
+use File::Copy;
+
+
 
 #
 # Exit codes:
@@ -57,16 +59,18 @@ use IO::File;
 # 4    - source_file_name does not exist.
 # 5    - destination file does not exist (not allowed to create new files).
 # 6    - Some file operation failed.
+# 7    - Invalid table filename.
 #
-$noprint = 0;
+my $noprint = 1;
 #
 #   Ensure we are www:
 #
 # 
+print ("In lcinstallfile\n") unless $noprint;
 
 my $wwwid=getpwnam('www');
-&disable_root_capability;
-if ($wwwid!=$>) {
+#&disable_root_capability;
+if ($wwwid!=$<) {
     print("User ID mismatch.  This program must be run as user 'www'\n")
 	unless $noprint;
     exit 1;
@@ -76,32 +80,56 @@ if ($wwwid!=$>) {
 #
 my $argc = scalar(@ARGV);
 if ($argc != 2) {
-    print("Usage: lcinstallfile sourcepath destfile\n") unlesss $noprint;
+    print("Usage: lcinstallfile sourcepath destfile had $argc parameters\n") unless $noprint;
     exit 2;
 }
-my $sorcepath = $ARGV[0];
+my $sourcepath = $ARGV[0];
 my $destfile  = $ARGV[1];
 
+print("From: $sourcepath to: $destfile\n") unless $noprint;
+
+
 # Ensure the source file exists, and root can write it.:
 
-&enable_root_capability;
+# since this is a setuid program, the sourcepath and destfile
+# must be pattern extracted else they are considered insecure and
+# therefore not validated.  
+# loncapa table files are all of the form.
+#  something.tab where something is all letters and _'s.
+#
+if ($sourcepath =~ /^([\w\/]+\.\w+)$/) {
+    $sourcepath = $1;
+} else {
+    print ("Invalid characters in filename '$sourcepath' \n") unless $noprint;
+    exit 7;
+}
+
+
 if (! -r $sourcepath) {
-    &disable_root_capability;
     print("File $sourcepath either does not exist or cannot be read") unless $noprint;
     exit 4;
     
 }
+&enable_root_capability;
+
 #
 #  Figure out where the lontab directory is and create the destinationfile name:
 #
 #  We're not allowed to create new files, only replace existing files
 #  so ensure that the final destination file actually exists.
 #
-my $config_vars = LONCAPA::Configuration::read_conf('loncapa.conf');
-my %config      = %{$configvars};
-my $tab_dir     = $config{'lonTabDir'};
 
-my $final_file  = $tabdir.'/'.$destfile;
+
+#
+# Now sanitize the final file:
+
+my $final_file;
+if ($destfile =~ /^([\w\/]+\.\w+)$/) {
+    $final_file = $1;
+} else {
+    print ("'$final_file' failed regexp match\n") unless $noprint;
+    exit 7;
+}
 
 if (! -w $final_file) {
     &disable_root_capability;
@@ -111,16 +139,17 @@ if (! -w $final_file) {
 #
 # Copy the destination file to a backup:
 #
-if (!File::Copy($final_file, $final_file.'.backup')) {
+if (!copy($final_file, $final_file.'.backup')) {
     &disable_root_capability;
     print ("Failed to create backup copy of $final_file\n") unless $noprint;
     exit 6;
 }
+&enable_root_capability;
 
 #  Install the new file to a temp file in the same dir so it can be mv'd in place
 #  this prevents the possibility we wind up with a partial file.:
 
-if (!File::Copy($sourcepath, $final_file.'.new')) {
+if (!copy($sourcepath, $final_file.'.new')) {
     &disable_root_capability;
     print("Failed to copy $sourcepath to a tempfile\n") unless $noprint;
     exit 6;
@@ -128,42 +157,42 @@ if (!File::Copy($sourcepath, $final_file
 #
 #  Move the temp file to the final file
 #
-if (!rename($final_path.'.new', $final_path)) {
+if (!rename($final_file.'.new', $final_file)) {
     &disable_root_capability;
-    print ("Failed to move installed file $final_path.new to final resting place\n")
+    print ("Failed to move installed file $final_file.new to final resting place\n")
 	unless $noprint;
     exit 6;
 }
 
 #  Ready to exit with success
 
-&disble_root_capability;
-print ("$sourcepaht installed to $final_file\n") unless $noprint;
+&disable_root_capability;
+print ("$sourcepath installed to $final_file\n") unless $noprint;
 exit 0;
 
+
 #-------------------------------------------------------------------------
 #
 #  subs that control the setuid-edness of the program.
 
-# ---------------------------------------------- have setuid script run as root
+#  have setuid script run as root
 sub enable_root_capability {
     if ($wwwid==$>) {
 	($<,$>)=($>,0);
 	($(,$))=($),0);
-    }
-    else {
+    } else {
 	# root capability is already enabled
     }
+    print ("Effective uid = $>\n");
     return $>;
 }
 
-# ----------------------------------------------- have setuid script run as www
+#  have setuid script run as www
 sub disable_root_capability {
     if ($wwwid==$<) {
 	($<,$>)=($>,$<);
 	($(,$))=($),$();
-    }
-    else {
+    } else {
 	# root capability is already disabled
     }
 }