Re: safe_shell_exec extension for consideration

On May 23, 2010, at 5:56 PM, Richard Quadling <rquadling@googlemail.com> wrote:

On 23 May 2010 22:42, Dave McMurtrie <dave64@andrew.cmu.edu> 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