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Date: Sun, 14 Nov 2010 21:43:57 -0800
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To: Andi Gutmans <andi@zend.com>
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Subject: Re: [PHP-DEV] Adding path_len to all stream functions in trunk
From: rasmus@lerdorf.com (Rasmus Lerdorf)

Right, but the root of the problem is where to do the invalidation check
of bogus file path strings.  Like checking for bogus null bytes in them.
 Right now:

file_exists($file . '.txt');
and
file_exists($file);

will check the same file if $file has a \0 stuck onto the end.  This can
lead to security problems.

So, either we need to put some sort of check ahead of any and all calls
that pass paths to the filesystem functions, or we need to change those
filesystem functions to do the check natively.  For the second option to
work, we obviously need to pass in more than a naked char *.

My worry with the first option is that we then push this out to every
extension and it gets pretty messy.  However, doing it this way would
let us do it without breaking binary compatibility in 5.3.

-Rasmus

On 11/14/10 9:35 PM, Andi Gutmans wrote:
> Hi Rasmus,
> 
> Hope I understood the problem correctly. If not, this answer won't make sense :)
> I do not see a major problem in passing path_len but wonder how much it'd actually solve as we end up calling OS APIs that do not accept path_len, no? I assume we don't want to start searching all these strings for invalid chars before we pass them to the OS.
> 
> Andi
> 
>> -----Original Message-----
>> From: Rasmus Lerdorf [mailto:rasmus@lerdorf.com]
>> Sent: Sunday, November 14, 2010 11:54 AM
>> To: internals
>> Subject: [PHP-DEV] Adding path_len to all stream functions in trunk
>>
>> I think we need to pass along the string length to all the stream functions to
>> maintain binary string safety through this code.  This would fix annoying
>> problems like http://bugs.php.net/39863 and a bunch of similar issues.
>> Obviously not something we can do in 5.3 without breaking binary compatibility
>> though.  Although we might be able to do something if we assume only chars
>> valid in the current charset is valid in file paths.
>>
>> Anybody have any other thoughts on this one?
>>
>> -Rasmus
>>
>> --
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