Mailing List Archive

On Oct 20, 2004, at 3:47 PM, Markus Klaus Schäffauer wrote:
> This is the error message we get:
>
> Warning: shell_exec,popen,escapeshellcmd,proc_open,proc_nice() has
> been disabled for security reasons in
> /www/htdocs/db/wiki/includes/Image.php on line 179

Enable those functions. If you don't control your host, ask your
service provider for help.

-- brion vibber (brion @ pobox.com)

Hi Brion,

thank you for your clear answer (see above)... We asked our service
provider and he told us to change to another server with an open
mod_php, but telling us that this one has an serious security hole.

Do you see any other solution to our problem? Will there come up a fix
to enable the functionality of thumb generation in another way?

I can not understand that a software like Mediawiki depends on functions
that are disabled for security reasons. May there be a way to tell it to
the provider that he can enable the functions without producing a
security hole?

thanks,
Markus

Brion Vibber schrieb:

> On Oct 20, 2004, at 3:47 PM, Markus Klaus Schäffauer wrote:
>
>> This is the error message we get:
>>
>> Warning: shell_exec,popen,escapeshellcmd,proc_open,proc_nice() has
>> been disabled for security reasons in
>> /www/htdocs/db/wiki/includes/Image.php on line 179
>
>
> Enable those functions. If you don't control your host, ask your
> service provider for help.
>
> -- brion vibber (brion @ pobox.com)
>
>------------------------------------------------------------------------
>
>_______________________________________________
>MediaWiki-l mailing list
>MediaWiki-l@Wikimedia.org
>http://mail.wikipedia.org/mailman/listinfo/mediawiki-l
>
>

On Oct 25, 2004, at 11:55 PM, Markus Klaus Schäffauer wrote:
> thank you for your clear answer (see above)... We asked our service
> provider and he told us to change to another server with an open
> mod_php, but telling us that this one has an serious security hole.
>
> Do you see any other solution to our problem? Will there come up a fix
> to enable the functionality of thumb generation in another way?

There is support for using PHP's GD library interface to generate
thumbnails, but a) it doesn't work as well, producing lower quality
images and b) if it were available the installer should have selected
it instead of ImageMagick.

You might double-check in case the installer was mistaken or you edited
the LocalSettings.php file by hand; try setting $wgUseImageMagick =
false; and it will try to use the GD library functions instead.

> I can not understand that a software like Mediawiki depends on
> functions that are disabled for security reasons. May there be a way
> to tell it to the provider that he can enable the functions without
> producing a security hole?

Often mass hosting providers disable things like this because their
setups are inherently insecure, with many users' accounts running under
the same privileges on an unpartitioned server. A secure multi-user
hosting solution would include separate virtual servers for each user
account (chroot or jail partitions, usually) such that no user's
programs could affects any other user's files. Instead, they will
sometimes just disable large swaths of functionality so make it harder
to do anything: if you can't modify files or run external programs it's
hard to make trouble.

-- brion vibber (brion @ pobox.com)

Hi Brion,

> You might double-check in case the installer was mistaken or you
> edited the LocalSettings.php file by hand; try setting
> $wgUseImageMagick = false; and it will try to use the GD library
> functions instead.

This is what I did - I put "$wgUseImageMagick = false" and commented the
following line out (the path to convert). The result is what we were
looking for: thumb resizing works again with jpg and png.

Now I wonder: How did the problem begin? As I know (and checked in
former installations), default is $wgUseImageMagick = false. I only
activated ImageMagick when the trouble with png-thumbs began. The result
was worse: we neither could use png nor jpg.

So turning back to default resolved everything... I can not understand
the logic of that procedure but may be others can and so it may
contribute to help others.

Thank you for your hints,
Markus

On Oct 26, 2004, at 1:57 AM, Markus Klaus Schäffauer wrote:
> This is what I did - I put "$wgUseImageMagick = false" and commented
> the following line out (the path to convert). The result is what we
> were looking for: thumb resizing works again with jpg and png.
>
> Now I wonder: How did the problem begin? As I know (and checked in
> former installations), default is $wgUseImageMagick = false. I only
> activated ImageMagick when the trouble with png-thumbs began. The
> result was worse: we neither could use png nor jpg.

What, specifically, was the original trouble? I've only seen the
ImageMagick-related error messages in your posts.

-- brion vibber (brion @ pobox.com)

Hi,
this was the trouble we had: the png-thumbs remain black (or sometimes
even white), but the png beyond is shown without error.
Since we changed back to ImageMagick=false, fortunately most png-thumbs
work well, but some (we uploaded before) still remain black.
Thanks so far.
Markus

Brion Vibber schrieb:

> On Oct 26, 2004, at 1:57 AM, Markus Klaus Schäffauer wrote:
>
>> This is what I did - I put "$wgUseImageMagick = false" and commented
>> the following line out (the path to convert). The result is what we
>> were looking for: thumb resizing works again with jpg and png.
>>
>> Now I wonder: How did the problem begin? As I know (and checked in
>> former installations), default is $wgUseImageMagick = false. I only
>> activated ImageMagick when the trouble with png-thumbs began. The
>> result was worse: we neither could use png nor jpg.
>
>
> What, specifically, was the original trouble? I've only seen the
> ImageMagick-related error messages in your posts.
>
> -- brion vibber (brion @ pobox.com)
>
>------------------------------------------------------------------------
>
>_______________________________________________
>MediaWiki-l mailing list
>MediaWiki-l@Wikimedia.org
>http://mail.wikipedia.org/mailman/listinfo/mediawiki-l
>
>

On Oct 27, 2004, at 11:48 AM, Markus Klaus Schäffauer wrote:
> Hi,
> this was the trouble we had: the png-thumbs remain black (or sometimes
> even white), but the png beyond is shown without error.

Internet Explorer for Windows and transparent PNGs specifically, or all
PNGs? It used to default to specifying black as the background chunk
which would lead IE to render transparent images on a solid black
background; at some point it was changed to tell ImageMagick to specify
a white background color for IE's sake. (Normal browsers continue to
display transparency correctly.)

> Since we changed back to ImageMagick=false, fortunately most
> png-thumbs work well, but some (we uploaded before) still remain
> black.

If you delete the thumbnail files and let them regenerate, how do they
look?

-- brion vibber (brion @ pobox.com)