Problem with PHP4, chroot and sendmail

[Anon]

I have been trying to overcome the problem of not being able to send mail or running programs from PHP in a chrooted environment.

My set up:

Linux 2.2.14
Apache 1.3.14
php-4.0.3pl1

PHP4 was compiled with the following params:

./configure --disable-debug \
--enable-track-vars \
--with-apache=../apache_1.3.14

safe_mode = off
sendmail_path = /usr/sbin/sendmail -t -i

Apart from the prints and phpinfo(), the following snippet of PHP program produces NOTHING at all.

$status = mail($recipient, $subject, $message, $headers);
print "Mail Status = " . $status;
print $status ? "OK<br>" : "Failed<br>"; // Always show "Failed"
print "Doing chdir and system<br>";
chdir("/usr/local"); system("ls"); // Returns nothing
print "Execing perl<br>";
exec('jhgjgjhgjhgjhg'); // Should generate an error but don't
print exec('/usr/bin/perl -h') . "<br>"; // Returns nothing
phpinfo(); // This is fine

It is obvious that PHP is not executing any programs. Our chroot environment only have the following programs (they all work fine
in chroot otherwise):

perl
gzip
sendmail

Do I need a shell to run sendmail and other programs within PHP? Any help
as to why I couldn't run any program in PHP within a chroot environment is greatly appreciated.

Regards,

Kwong Li
London, UK

[Anon]

Thank you Richard Lynch for answering my question. I couldn't find Mr. Lynch's posting here although it was included in the PHP summaries yesterday.

I have omitted to say that the two parameters shown (safe_mode and sendmail_path) were default values so the quotation marks suggestion does not apply on this occasion. However, I have tried that too without success.

Regards,

Kwong Li
London, UK

[Anon]

After many days of searching and examination, I have finally found the cause of our problem of not being able to send mail from PHP or indeed run any external programs.

One of the main objectives of running a chroot environment is to limit the number of executables available for a potential intruder. Our chroot "jail" only have a handful of programs that are essential for the operation of the Apache server and associated facilities. However, I didn't realise that sh is also essential for running sendmail and all other external programs in PHP4. Perl, through CGI, runs sendmail fine without any shell being available.

By adding sh to our chroot environment, everything is working properly now. It is a shame that the presence of the sh shell would somewhat diminish the main purpose of having a chroot jail.

Regards,

Kwong Li
London, UK