imagejpg & safe mode & chmod()

**John Murtari** · May 24 '06, 06:25 PM

Re: imagejpg & safe mode & chmod() and uploads

"Rik" <google@tfwasmu s.enschedenet.n l> writes:
[color=blue]
> The problem at hand:
> In a restricted area I let a user upload an image, no problem
> The image gets scaled down with imagecopyresamp led(), and stored with
> imagejpeg($resi zed_img,'/path/to/target/image.jpg')
>
> Problem is: because of safe_mode restrictions I cannot access it from
> the server, only by http://domain.com/images/new_image.jpg.
> I've tried:
> imagejpeg($resi zed_img,'/path/to/target/image.jpg')
> directly followed by:
> chmod('/path/to/target/image.jpg',0777 );
>
> But the same script is also refused chmod().... It should be the same
> user that creates the file, but unfortunately safe_mode won't let me
> chmod() it.
>
> I'm using referring to the image later on by the URL instead of the
> /path/ as a temporary solution to make it work, but now the script
> doesn't have any permission to unlink() the file at a later stage,
> which is functionality I desperately need. How will I be able to
> achieve this?
>
> I thought bout using an FTP connection as a temporary measure, but no
> go there:
> 24-05-06 17:50:55 SITE CHMOD 777 /path/to/image.jpg
> 24-05-06 17:50:55 550 /path/to/image.jpg: Operation not permitted.
>
> The only solution I can think of right now is to catch imagejpg() in an
> output buffer, don't use the filesystem but an ftp-connection to save
> the file, and chmod it by ftp afterwards. An ugly solution, but the
> only thing workable right now...
>
> phpinfo():
> open_basedir /home/user no value
> safe_mode On On
> safe_mode_exec_ dir /usr/local/php/bin /usr/local/php/bin
> safe_mode_gid Off Off
> safe_mode_inclu de_dir no value no value[/color]

I'm not sure how you are setup by your description above.
Your provider may have opened some permissions for you on the current
directory you are uploading to? Normally, assuming PHP is run as a
module in Apache, your scripts will execute as the Apache user and any
file uploaded will be owned by the Apache user. If your visitors are
able to upload files, either the directory is owned by Apache - or -
it is owned by you with open write permissions to anyone.

Any attempt to access the file through PHP would fail after
that if safe_mode is On, because your script has a different owner
than the file you want to access. Any attempt at chmod, from FTP
or even the command line would fail since you do not own the file.
However, and I'm pretty sure of this, if you own the directories,
you are allowed to do a 'rename' and move the file from a directory
you own to another -- or even delete the file from the directory.
Please confirm who owns the files after they are uploaded, and
who the directory owner is and directory permmissions.

--
John
_______________ _______________ _______________ _______________ _______
John Murtari Software Workshop Inc.
jmurtari@follow ing domain 315.635-1968(x-211) "TheBook.Co m" (TM)
http://thebook.com/

**Rik** · May 24 '06, 08:25 PM

Re: imagejpg & safe mode & chmod() and uploads

Hmmmz, newsserver was up for a minute, then down again, oh well:

The exact way thing are made now:

In the object handling the post:

if(!file_exists ($_SERVER['DOCUMENT_ROOT'].'/path/to/'.$id)){
$makedir = mkdir($_SERVER['DOCUMENT_ROOT'].'/path/to/'.$id, 0777);
if(!$makedir){
$this->set_error('Cou ld not make directory.');
return false;
}
$chmoddir = chmod($_SERVER['DOCUMENT_ROOT'].'/path/to/'.$id, 0777);
if(!$chmoddir){
$this->set_error('Cou ld not set dir's permission');
return false;
}
}
foreach($_FILES as $file){
$imagehandler->handle($file['tmp_name'],
$_SERVER['DOCUMENT_ROOT'].'/path/to/'.$id,$file['name']);
}

$imagehandler is another object, which basically validates, resizes and
then:
imagejpeg($new, $targetdir.'/'.$targetname);

Instead of this, I've trief touch($targetdi r.'/'.$targetname), which
already gives an error.

It seems the same script which has created a dir has limited
permissions in that dir?

I've used this testscript to check some things:

<pre>
<?php
error_reporting (E_ALL);

$dir = $_SERVER['DOCUMENT_ROOT'].'/images/houses/242';
$file = '/Logo2.jpg';
$filegroupdir = filegroup ($dir.'/');
$filegroupfile = filegroup ($dir.$file);
$userdir = fileowner($dir. '/');
$userfile = fileowner($dir. $file);

echo "Own group:".posix_g etegid();
print_r(posix_g etgrgid(posix_g etegid()));
echo "Own user:".posix_ge teuid();
print_r(posix_g etpwuid(posix_g eteuid()));

echo "Dir group: ".$filegroupdir ;
print_r(posix_g etgrgid($filegr oupdir));
echo "File group: ".$filegroupfil e;
print_r(posix_g etgrgid($filegr oupfile));

echo "Dir user: ".$userdir;
print_r(posix_g etpwuid($filegr oupdir));
echo "File user: ".$userfile ;
print_r(posix_g etpwuid($filegr oupfile));
?>
</pre>

Which outputs:
Warning: filegroup(): SAFE MODE Restriction in effect. The script
whose uid is 1149 is not allowed to access /home/user/path/to/image.jpg
owned by uid 65534 in /home/user/path/tesst.php on line 8

Warning: fileowner(): SAFE MODE Restriction in effect. The script
whose uid is 1149 is not allowed to access /home/user/path/to/image.jpg
owned by uid 65534 in /home/user/path/tesst.php on line 10

Own group:65534Arra y
(
[name] => nobody
[passwd] => *
[members] => Array
(
)

[gid] => 65534
)
Own user:65534Array
(
[name] => nobody
[passwd] => *
[uid] => 65534
[gid] => 65534
[gecos] => Unprivileged user
[dir] => /usr/nobody
[shell] => /sbin/nologin
)
Dir group: 1004Array
(
[name] => group
[passwd] => *
[members] => Array
(
)

[gid] => 1004
)
File group: -snip false-
Dir user: 65534Array
(
[name] => 25m_user
[passwd] => *
[uid] => 1004
[gid] => 1004
[gecos] => User &
[dir] => /home/25m_user
[shell] => /usr/bin/true
)
File user: -snip false-

On trying to delete the image:
Warning: unlink(): SAFE MODE Restriction in effect. The script whose
uid is 1149 is not allowed to access /home/user/path/to/image.jpg
owned by uid 65534

I am very, very confused. I'll have to read up on file/userpermissions
I believe.
Everthing seems to result from a dynamically created dir, in which te
script can write, until it is terminated. Userfilowner seems the same
as myself, but not as the script...

Standard solution as touch($file) before($img,$fi le) won't work
either...
I'll try creating chmodding only the directory with FTP, and saving the
images dynamically. I'll keep you updated.

Grtz,
--
Rik Wasmus

**Rik** · May 24 '06, 09:15 PM

Re: imagejpg & safe mode & chmod() and uploads

Letting the script connect by FTP and creating & chmodding the
direcotiry like that will indeed make it possible to access the files
locally or unlink()ing them.

A very ugly solution IMHO, but at this time I'm just relieved that
works.

I really should set up a server with that detestable safe_mode locally
here, this isn't funny when you're supposed to have a finished
product..

I'll be using this snippet at home from now on a think:
<?php
$list = ini_get_all();
$phpini = '';
foreach($list as $name => $setting){
if($setting['access'] > 3){
$phpini = $name.' = '.$setting['local_value'],"\n";
}
}
header('Content-type: text/plain');
header('Content-Disposition: attachment; filename="php.i ni"');
echo $phpini;
?>

imagejpg & safe mode & chmod()

imagejpg & safe mode & chmod()

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