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From Sander Temme <scte...@apache.org>
Subject Re: [users@httpd] Apache 2.2.15 says You do not have permission to view [this file]
Date Fri, 30 Jul 2010 07:13:28 GMT
James, 

The Apache HTTP Server needs read access to its configuration files and the files it serves.
 In and of itself, the server does not need write access anywhere on the system: even its
log files are opened for write when the server is still root, and the open file descriptors
passed to the child processes which change their user id to the lesser privileged user.  

Read access only.  The web server user should not own, or be able to write to, its configuration
files or content.  

Content, other than CGI scripts, generally does not need Execute permissions.  Even PHP files
that are interpreted by the server do not need to be Executable.  

Certain applications, especially publishing platforms and Content Management Systems that
you manage and populate through the web server itself using a browser, require that certain
directories on the system be made writable by the web server user.  You can do this by changing
the owner of the directory to that user (usually www but ymmv), or by making the directory
group-writable and changing the group to the group as which Apache runs. 

Making directories writable by the web server should be done only with care and consideration.
 The usual threat model is that someone manages to upload (for instance) a PHP script of their
own making into the document root, and simply executes that by accessing it through a browser.
 Now someone is executing code on your machine.  Google for 'r57' for an example of what such
code can do.  

If a web app needs writable directories, it's often better to have those outside the DocumentRoot:
that way the uploads can't be accessed from the outside through a direct URL.  Some applications
(Wordpress for instance) support this, others do not.  

In many cases, writable directories are not strictly necessary even though the web app might
like them: rather than upload plugins (which contain code that gets executed or interpreted,
yech!) through the web browser, upload them through ssh and manually unpack them on the server.
 The CMS Joomla! likes to write its configuration file to the Document Root on initial install
(which promptly becomes a popular attack target) but if it can't write to the Document Root,
it will output the config to the browser to the user can manually upload it.  

Hope this helps.  

S.

On Jul 29, 2010, at 5:35 PM, James Godrej wrote:

> This I understand.
> But then do other users  not need read write permissions.
> There is hardly any thing given on this page
> http://httpd.apache.org/docs/trunk/misc/security_tips.html#serverroot
> You mentioned ServerRoot not be chowned to Apache.
> But if not then to what should it be and there is nothing about Document Root to be chowned
?
> Who should own the Document Root there are many applications I download from internet
in their README pages it says 
> to chown those directories to apache.
> Otherwise it never worked.
> What should I do in this situation?
> 
> From: Eric Covener <covener@gmail.com>
> To: users@httpd.apache.org
> Sent: Thu, 29 July, 2010 10:45:53 PM
> Subject: Re: [users@httpd] Apache 2.2.15 says You do not have permission to view [this
file]
> 
> > Oh man an experienced sys admin told me to do it that way.
> > Please tell me what is wrong in this and where is this documented on Apache
> > docs.
> > I want to read.
> 
> 
> This is a general principle -- don't grant more access than necessary.
> Apache doesn't need to own files to be able to serve (read) them.
> 
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> 



-- 
Sander Temme
sctemme@apache.org
PGP FP: FC5A 6FC6 2E25 2DFD 8007  EE23 9BB8 63B0 F51B B88A





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