Exec with PHP-FPM on nginx (under chroot) returns nothing

Question

I've created a nginx server in a chroot at /srv/http with php-fpm. Both services use the http user and it works fine. The problem comes when I try to run an exec command such as

echo shell_exec('/usr/bin/ls');

There is no output at all on the web page or in the errors. I've also tried

error_log(shell_exec('/usr/bin/ls');

and still nothing.

Things I've Tried or Know:

1. safe mode off
2. exec enabled
3. user is http (using phpinfo())
4. display_errors = on
5. error_reporting = E_ALL
6. sudo /usr/bin/chroot --userspec=http:http /srv/http ls works fine
7. Can create file and read from it using file_puts_content and fopen/fread
8. tried shell_exec,exec,system, and passthrough - nothing worked
9. tried appending 2>&1 to the end of the command and nothing
10. I've copied all the executables and libraries necessary over
11. all libraries, binaries, and everything under /srv/http/www (where the webpages are) have executable and read permissions
12. doc_root is www

As far as I know, everything works in the chroot, except shell commands through php-fpm. Anyone have any idea where I went wrong and how to fix it?

Answer 1

This may sound stupid but you must just copy /bin/sh (not /bin/bash !) to you chroot .

For example see this question: How do I change the shell for php's exec()

Answer 2

If you chroot to some directory, then this directory becomes the root for all your PHP scripts. That means, that if you execute /usr/bin/ls from within PHP, it will try to exectue /srv/http/usr/bin/ls instead.

You can copy the executable to that directory - but be aware of the security implications. If you copy critical system executables into the chrooted directory you basically bypass the positive effects of chroot .

Answer 3

I get no output for

echo shell_exec('/usr/bin/ls');

either. Presumably because ls isn't a file but a built-in command. Running:

echo shell_exec('ls');

outputs:

css demos favicon.ico images js path.php robots.txt routing.php test

which is the list of files in my root directory for the site.