Annotation of loncom/lchtmldir, revision 1.13

1.7       albertel    1: #!/usr/bin/perl
1.1       foxr        2: 
                      3: # The Learning Online Network with CAPA
                      4: #
                      5: # Copyright Michigan State University Board of Trustees
                      6: #
                      7: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
                      8: #
                      9: # LON-CAPA is free software; you can redistribute it and/or modify
                     10: # it under the terms of the GNU General Public License as published by
                     11: # the Free Software Foundation; either version 2 of the License, or
                     12: # (at your option) any later version.
                     13: #
                     14: # LON-CAPA is distributed in the hope that it will be useful,
                     15: # but WITHOUT ANY WARRANTY; without even the implied warranty of
                     16: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     17: # GNU General Public License for more details.
                     18: #
                     19: # You should have received a copy of the GNU General Public License
                     20: # along with LON-CAPA; if not, write to the Free Software
                     21: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
                     22: #
                     23: # /home/httpd/html/adm/gpl.txt
                     24: #
                     25: # http://www.lon-capa.org/
                     26: #
                     27: #  lchtmldir - LONC-CAPA setuid script to:
                     28: #              o If necessary, add a public_html directory 
                     29: #                to the specified user home directory.
                     30: #              o Set the permissions according to the authentication type.
                     31: #
                     32: #  Motivations:
                     33: #     Originally, account creation would create a public_html
                     34: #     directory for unix authorized people only.  It is possible to have
                     35: #     Kerberos, internal and locally authorized 'users' which may be authors
                     36: #     and hence need a properly owned an protected public_html directory
                     37: #     to serve as their construction space.
                     38: #
                     39: #  Author:
                     40: #    Ron Fox
                     41: #    NSCL
                     42: #    Michigan State University8
                     43: #    East Lansing, MI 48824-1321
                     44: 
                     45: #   General flow of control:
                     46: #   1. Validate process state (must be run as www).
                     47: #   2. Validate parameters:  Need two parameters:
                     48: #         o Homedir  - Home diretory of user 
                     49: #         o Username - Name of the user.
                     50: #         o AuthMode - Authentication mode, can be:
                     51: #                      - unix
                     52: #                      - internal
                     53: #                      - krb4
                     54: #                      - localauth
                     55: #  3. Untaint the usename and home directory
                     56: #
                     57: #  4. As root if necessary, create $Homedir/public_html
                     58: #  5. Set ownership/permissions according to authentication mode (AuthMode)
                     59: #       - unix - ~owner:www/2775
                     60: #       - krb4 - ~owner:www/2775
                     61: #       - internal - www:www/2775
                     62: #       - local    - www:www/2775
                     63: #
                     64: 
                     65: #
                     66: #   Take a few precautions to be sure that we're not vulnerable to trojan
                     67: #   horses and other fine issues:
                     68: #
                     69: use strict; 
1.10      foxr       70: use Fcntl qw(:mode);
                     71: use DirHandle;
1.12      foxr       72: use POSIX;
1.1       foxr       73: 
                     74: $ENV{'PATH'} = '/bin:/usr/bin:/usr/local/sbin:/home/httpd/perl';
                     75: delete @ENV{qw{IFS CDPATH ENV BASH_ENV}};
                     76: 
1.12      foxr       77: my $DEBUG = 1;                         # .nonzero -> Debug printing enabled.
1.10      foxr       78: my $path_sep = "/";		# Unix like operating systems.
1.1       foxr       79: 
                     80: 
                     81: # If the UID of the running process is not www exit with error.
                     82: 
                     83: if ($DEBUG) {
                     84:     print("Checking uid...\n");
                     85: }
                     86: my $wwwid = getpwnam('www');
                     87: &DisableRoot;
                     88: if($wwwid != $>) {
                     89:     if ($DEBUG) {
                     90: 	print("User ID incorrect.  This program must be run as user 'www'\n");
                     91:     }
                     92:     exit 1;			# Exit with error status.
                     93: }
                     94: 
                     95: # There must be three 'command line' parameters.  The first
                     96: # is the home directory of the user.
                     97: # The second is the name of the user.  This is only referenced
                     98: # in code branches dealing with unix mode authentication.
                     99: # The last is the authentication mode which must be one of unix, internal
                    100: # krb4 or localauth.
                    101: #   If there is an error in the argument count or countents, we exit with an
                    102: # error.
                    103: 
                    104: if ($DEBUG) {
                    105:     print("Checking parameters: \n");
                    106: }
                    107: if(@ARGV != 3) {
                    108:     if($DEBUG) {
                    109: 	print("Error: lchtmldir need 3 parameters \n");
                    110:     }
                    111:     exit 2;
                    112: }
                    113: my ($dir,$username,$authentication) = @ARGV;
                    114: 
                    115: if($DEBUG) {
                    116:     print ("Directory = $dir \n");
                    117:     print ("User      = $username \n");
                    118:     print ("Authmode  = $authentication \n");
                    119: 
                    120: }
                    121: 
1.2       foxr      122: if( $authentication ne "unix:"     &&
                    123:     $authentication ne "internal:" &&
1.4       matthew   124:     $authentication !~ /^krb(4|5):(.*)/ &&
1.2       foxr      125:     $authentication ne "localauth:") {
1.1       foxr      126:     if($DEBUG) {
                    127: 	print("Invalid authentication parameter: ".$authentication."\n");
                    128: 	print("Should be one of: unix, internal, krb4, localauth\n");
                    129:     }
                    130:     exit 3;
                    131: }
                    132: 
                    133: # Untaint the username.
                    134: 
                    135: my $match = $username =~ /^(\w+)$/;
                    136: my $patt  = $1;
                    137:  
                    138: if($DEBUG) {
                    139:    print("Username word match flag = ".$match."\n");
                    140:     print("Match value = ".$patt."\n");
                    141: }
                    142: 
                    143: my $safeuser = $patt;
                    144: if($DEBUG) {
                    145:     print("Save username = $safeuser \n");
                    146: }
                    147: if(($username ne $safeuser) or ($safeuser!~/^[A-za-z]/)) {
                    148:     if($DEBUG) {
                    149: 	print("User name $username had illegal characters\n");
                    150:     }
                    151:     exit 4;
                    152: }
                    153: 
                    154: #untaint the base directory require that the dir contain only 
                    155: # alphas, / numbers or underscores, and end in /$safeuser
                    156: 
                    157: $dir =~ /(^([\w\/]+))/;
                    158: 
                    159: my $dirtry1 = $1;
                    160: 
                    161: $dir =~ /$\/$safeuser/;
                    162: my $dirtry2 = $1;
                    163: 
                    164: if(($dirtry1 ne $dir) or ($dirtry2 ne $dir)) {
                    165:     if ($DEBUG) {
                    166: 	print("Directory $dir is not a valid home for $safeuser\n");
                    167:     }
                    168:     exit 5;
                    169: }
                    170: 
                    171: 
                    172: # As root, create the directory.
                    173: 
1.9       foxr      174: my $homedir = $dirtry1;
                    175: my $fulldir = $homedir."/public_html";
                    176: 
1.1       foxr      177: if($DEBUG) {
                    178:     print("Full directory path is: $fulldir \n");
                    179: }
                    180: if(!( -e $dirtry1)) {
                    181:     if($DEBUG) {
                    182: 	print("User's home directory $dirtry1 does not exist\n");
                    183:     }
1.4       matthew   184:     if ($authentication eq "unix:") {
                    185:         exit 6;
                    186:     }
1.1       foxr      187: }
                    188: &EnableRoot;
                    189: 
1.3       foxr      190: &System("/bin/mkdir -p $fulldir")   unless (-e $fulldir);
1.1       foxr      191:     unless(-e $fulldir."/index.html") {
                    192: 	open OUT,">".$fulldir."/index.html";
                    193: 	print OUT<<END;
                    194: 	<html>
                    195: 	<head>
                    196: 	<title>$safeuser</title>
                    197:         </head>
1.5       www       198:         <body bgcolor="#ccffdd">
                    199:         <h1>$safeuser Construction Space</h1>
                    200:           <h2>
                    201:             The Learning<i>Online</i> Network with Computer-Assisted Personalized Approach
                    202:           </h2>
1.1       foxr      203:           <p>
1.5       www       204: This is your construction space within LON-CAPA, where you would construct resources which are meant to be
                    205: used across courses and institutions.
1.1       foxr      206:           </p>
                    207:           <p>
1.5       www       208: Material within this area can only be seen and edited by $safeuser and designated co-authors. To make
                    209: it available to students and other instructors, the material needs to be published.
1.1       foxr      210:           </p>
                    211:         </body>
                    212:        </html>
                    213: END
                    214:     close OUT;
                    215:     }
1.9       foxr      216: 
1.13    ! foxr      217: &System("/bin/chmod  02770  $fulldir");
        !           218: &System("/bin/chmod  0770  $fulldir"."/index.html");
1.1       foxr      219: 
                    220: 
                    221: # Based on the authentiation mode, set the ownership of the directory.
                    222: 
1.2       foxr      223: if($authentication eq "unix:") {	# Unix mode authentication...
1.13    ! foxr      224:     &System("/bin/chown -R   $safeuser:www"." ".$fulldir);
1.6       albertel  225:     &JoinGroup($safeuser);
1.4       matthew   226: } else {
                    227:     # Internal, Kerberos, and Local authentication are for users
                    228:     # who do not have unix accounts on the system.  Therefore we
                    229:     # will give ownership of their public_html directories to www:www
1.9       foxr      230:     # If the user is an internal auth user, the rest of the directory tree
                    231:     # gets owned by root.  This chown is needed in case what's really happening
                    232:     # is that a file system user is being demoted to internal user...
                    233: 
                    234:     if($authentication eq "internal:") {
1.11      foxr      235: 	#  In case the user was a unix/filesystem authenticated user,
                    236: 	#  we'll take a bit of time here to write  a script in the
                    237: 	#  user's home directory that can reset ownerships and permissions
                    238: 	#  back the way the used to be.
                    239: 
1.12      foxr      240: 	# This can take long enough for lond to time out, so we'll do it
                    241: 	# in a separate process that we'll not wait for.
                    242: 	#
                    243: 	my $fpid = fork;
                    244: 	if($fpid) {
                    245: 	    &DisableRoot;
                    246: 	    exit 0;
                    247: 	} else {
                    248: 	    print "Forked\n";
                    249: 	    POSIX::setsid();	# Disassociate from parent.
                    250: 	    print "Separate session\n";
                    251: 	    &write_restore_script($homedir);
                    252: 	    print "Restore script written\n";
                    253: 	    &System("/bin/chown -R root:root ".$homedir);
                    254: 	    &System("/bin/chown -R www:www  ".$fulldir);
                    255: 	    print "Exiting\n";
                    256: 	    exit 0;
                    257: 	}
                    258:     } else {
                    259: 	&System("/bin/chown -R www:www  ".$fulldir);
                    260:     }
1.11      foxr      261: 
1.1       foxr      262: }
                    263: &DisableRoot;
                    264: 
                    265: exit 0;
                    266: 
                    267: #----------------------------------------------------------------------
                    268: #
                    269: #  Local utility procedures.
                    270: #  These include:
                    271: #     EnableRoot - Start running as root.
                    272: #     DisableRoot- Stop running as root.
                    273: #     JoinGroup  - Join www to the specified group.
                    274: 
                    275: # Turn on as root:
                    276: 
                    277: sub EnableRoot {
                    278:     if ($wwwid==$>) {
                    279: 	($<,$>)=($>,$<);
                    280: 	($(,$))=($),$();
                    281:     }
                    282:     else {
                    283: 	# root capability is already enabled
                    284:     }
                    285:     if($DEBUG) {
1.4       matthew   286: 	print("Enable Root - id =  $> $<\n");
1.1       foxr      287:     }
                    288:     return $>;  
                    289: }
                    290: 
                    291: sub DisableRoot {
                    292:     if ($wwwid==$<) {
                    293: 	($<,$>)=($>,$<);
                    294: 	($(,$))=($),$();
                    295:     }
                    296:     else {
                    297: 	# root capability is already disabled
                    298:     }
                    299:     if($DEBUG) {
                    300: 	print("Disable root: id = ".$>."\n");
                    301:     }
                    302: }
                    303: 
                    304: sub JoinGroup {
                    305:     my $usergroup = shift;
                    306: 
                    307:     my $groups = `/usr/bin/groups www`;
1.6       albertel  308:     # untaint
1.8       albertel  309:     my ($safegroups)=($groups=~/:\s+([\s\w]+)/);
1.6       albertel  310:     $groups=$safegroups;
1.1       foxr      311:     chomp $groups; $groups=~s/^\S+\s+\:\s+//;
                    312:     my @grouplist=split(/\s+/,$groups);
                    313:     my @ugrouplist=grep {!/www|$usergroup/} @grouplist;
                    314:     my $gl=join(',',(@ugrouplist,$usergroup));
                    315:     if (&System('/usr/sbin/usermod','-G',$gl,'www')) {
                    316: 	if($DEBUG) {
                    317: 	    print "Error. Could not make www a member of the group ".
                    318: 		"\"$usergroup\".\n";
                    319: 	}
                    320: 	exit 6;
                    321:     }
                    322:     
                    323: }
                    324: 
                    325: 
                    326: 
                    327: sub System {
1.6       albertel  328:     my ($command,@args) = @_;
1.1       foxr      329:     if($DEBUG) {
1.6       albertel  330: 	print("system: $command with args ".join(' ',@args)."\n");
1.1       foxr      331:     }
1.6       albertel  332:     system($command,@args);
1.1       foxr      333: }
                    334: 
                    335: 
                    336: 
                    337: 
1.10      foxr      338: 
                    339: #
                    340: #   This file contains code to recursively process
                    341: #   a Directory.  This is a bit more powerful
                    342: #   than File::Find in that we pass the full
                    343: #   stat info to the processing function.
                    344: #     For each file in the specified directory subtree, 
                    345: #   The user's Code reference is invoked for all files, regular and otherwise
                    346: #   except:
                    347: #      ., ..
                    348: #
                    349: #  Parameters:
                    350: #     code_ref    - Code reference, invoked for each file in the tree.
                    351: #                   as follows:  CodeRef(directory, name, statinfo)
                    352: #                   directory the path to the directory holding the file.
                    353: #                   name      the name of the file within Directory.
                    354: #                   statinfo  a reference to the stat of the file.
                    355: #     start_dir   - The starting point of the directory walk.
                    356: #
                    357: # NOTE:
                    358: #   Yes, we could have just used File::Find, but since we have to get the
                    359: #   stat anyway, this is actually simpler, as File::Find would have gotten
                    360: #   the stat to figure out the file type and then we would have gotten it
                    361: #   again.
                    362: #
                    363: 
                    364: sub process_tree {
                    365:     my ($code_ref, $start_dir)  = @_;
                    366: 
                    367:     my $dir = new DirHandle $start_dir; 
                    368:     if (!defined($dir)) {
                    369:         print "Failed to  open dirhandle: $start_dir\n";
                    370:     }
                    371: 
                    372:     # Now iterate through this level of the tree:
                    373: 
                    374:     while (defined (my $name = $dir->read)) {
                    375: 	next if $name =~/^\.\.?$/;       # Skip ., .. (see cookbook pg 319)
                    376: 	
                    377: 	my $full_name   = $start_dir.$path_sep.$name; # Full filename path.
                    378: 	my @stat_info  = lstat($full_name);
                    379: 	my $mode       = $stat_info[2];
                    380: 	my $type       = $mode & 0170000; #  File type.
                    381: 
                    382: 	# Unless the file type is a symlink, call the user code:
                    383: 
                    384: 	unless ($type == S_IFLNK) {
                    385: 	    &$code_ref($start_dir, $name, \@stat_info);
                    386: 	}
                    387: 
                    388: 	# If the entry is a directory, we need to recurse:
                    389: 
                    390: 
                    391: 	if (($type ==  S_IFDIR) != 0) {
                    392: 	    &process_tree($code_ref, $full_name);
                    393: 	}
                    394:     }
                    395: 
                    396: }
                    397: #
1.11      foxr      398: #   Callback from process_tree to write the script lines
                    399: #   requried to restore files to current ownership and permission.
                    400: # Parameters:
                    401: #    dir         - Name of the directory the file lives in.
                    402: #    name        - Name of the file itself.
                    403: #    statinfo    - Array from lstat called on the file.
                    404: #
1.10      foxr      405: #
                    406: sub write_script {
                    407:     my ($dir, $name, $statinfo) = @_;
                    408: 
                    409:     my $fullname = $dir.$path_sep.$name;
                    410: 
                    411:     #  We're going to '' the name, but we need to deal with embedded
                    412:     #  ' characters.  Using " is much worse as we'd then have to
                    413:     #  escape all the shell escapes too.  This way all we need
                    414:     #  to do is replace ' with '\''
                    415: 
                    416:     $fullname =~ s/\'/\'\\\'\'/g;
                    417: 
                    418:     my $perms    = $statinfo->[2] & 0777; # Just permissions.
                    419:     printf CHMODSCRIPT "chmod 0%o '%s'\n", $perms, $fullname;
                    420:     printf CHMODSCRIPT "chown %d:%d '%s'\n", $statinfo->[4], $statinfo->[5], 
                    421:                                          $fullname
                    422: 
                    423: 
                    424: }
1.11      foxr      425: # 
                    426: #    Write a script in the user's home directory that can restore
                    427: #    the permissions and ownerhips of all the files in the directory
                    428: #    tree to their current ownerships and permissions.  This is done
                    429: #    prior to making the user into an internally authenticated user
                    430: #    in case they were previously file system authenticated and
                    431: #    need to go back.
                    432: #      The file we will create will be of the form
                    433: #        restore_n.sh  Where n is a number that we will keep
                    434: #   incrementing as needed until there isn't a file by that name.
                    435: #   
                    436: # Parameters:
                    437: #    dir      - Path to the user's home directory.
                    438: #
                    439: sub write_restore_script {
                    440:     my ($dir)   = @_;
                    441: 
                    442:     #   Create a unique file:
                    443: 
                    444:     my $version_number     = 0;
                    445:     my $filename           = 'restore_'.$version_number.'.sh';
                    446:     my $full_name           = $dir.$path_sep.$filename;
                    447: 
                    448:     while(-e $full_name) {
                    449: 	$version_number++;
                    450: 	$filename         = 'restore_'.$version_number.'.sh';
                    451: 	$full_name        = $dir.$path_sep.$filename;
                    452:     }
                    453:     # $full_name is the full path of a file that does not yet exist
                    454:     # of the form we want:
                    455: 
                    456:     open(CHMODSCRIPT, "> $full_name");
                    457: 
                    458:     &process_tree(\&write_script, $dir);
                    459: 
                    460:     close(CHMODSCRIPT);
                    461: 
                    462:     chmod(0750, $full_name);
                    463: 
                    464: }
1.10      foxr      465: 
                    466: 
                    467: 
                    468: 

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