Re: [PECL-DEV] safe_shell_exec extension for consideration

On May 23, 2010, at 5:56 PM, Richard Quadling  
<[email protected]> wrote:

> On 23 May 2010 22:42, Dave McMurtrie <[email protected]> wrote:
>> Hi,
>>
>> We're working to deploy an application using PHP and we'd  
>> ultimately like to
>> be able to fork/exec a child process without ever involving a shell  
>> for the
>> purpose of limiting our exposure to potential shell vulnerabilities.
>>
>> I noticed that shell_exec(), popen() and proc_open() all involve a  
>> shell, so
>> I wrote a quick extension that will do essentially what shell_exec 
>> () and
>> popen() do, but doesn't involve ever forking/execing a shell.
>>
>> I don't know if others might find this useful or not, so I'm  
>> sending this
>> note for consideration to have it added as an extension.  If  
>> there's a
>> better way to do what we're interested in, please let me know.  If  
>> any code
>> changes are required to allow this to be contributed, please let me  
>> know.
>>  If this is something you're simply not interested it, also let me  
>> know.
>>
>> At the very least, I suspect my tokenizer would require some  
>> additional
>> functionality, though it does what we currently need.
>>
>> You can download a tar/gz copy of the extension at:
>>
>> http://www.andrew.cmu.edu/user/dave64/safe_shell_exec.tar.gz
>>
>> Thank you,
>>
>> Dave
>>
>> --
>> PECL development discussion Mailing List (http://pecl.php.net/)
>> To unsubscribe, visit: http://www.php.net/unsub.php
>>
>>
>
> http://docs.php.net/manual/en/function.proc-open.php has a  
> bypass_shell option.
>

I saw that, but then I looked at the proc_open() code and discovered  
that option only works on Windows.

Perhaps the right thing to do would be to extend that to work on Unix  
as well. I considered that, but then I envisioned the possibility of  
adding further I/O redirection options in addition to just the  
MERGE_STDERR that I provided and thought that might get ugly tring to  
implement it cross-platform.

Regardless, thanks for looking.

Dave