Running system command from php

[proggybilly]

I am trying to put together a page that displays different information about the system. One of the commands I want to run is hdparm so that I can gather the hard drive serial number. My code looks like this:

$hd = system("hdparm -I /dev/sda");
echo $hd;

But I get nothing when I pull up the page to display.

Any help is greatly appreciated

 

[feherke]

Hi

Are you sure the webserver's user has permission to execute [tt]hdparm[/tt] ?

[tt]system()[/tt] returns only the last line of the output. If the output ends with an empty line, there will be nothing to see.

The serial number is not on the [tt]hdparm[/tt]'s last line. To grab the entire output use the backtick operators ( cheap & easy ) or the [tt]proc_open()[/tt]/[tt]proc_close()[/tt] functions ( better control ).

Feherke.

http://free.rootshell.be/~feherke/

 

[proggybilly]

Thanks, come to think of it, yes it is a blank line. I did not know that about system(). I will look into using your suggestions.


Again, thanks!

 

[proggybilly]

Also noticed that hdparm is owned by root.root so apache does not have permission.

 

[proggybilly]

ok so it eludes me, tried the backticks, proc_open/close, exec, passthru and even created a script to run hdparm set permissions to 777 +t and still cannot get anything to display on the screen.

Can anoyone else lend a hand?

 

[feherke]

Hi

I understand that you changed your code. Then please post it.


Feherke.

http://free.rootshell.be/~feherke/

 

[proggybilly]

ok I changed my code to be:

$hdd = `/usr/bin/runhd`;
echo $hdd;

I created the script runhd

#! /bin/sh
/sbin/hdparm -I /dev/sda

When I run the above runhd, as user other than root, I get an error:

/dev/sda: Permission Denied

 

[jpadie]

you need to be running as root or use sudo to access hdparm via php.

try something like this

$cwd = realpath('.');
$pwd = $cwd . '/pwd.php'
file_put_contents($pwd, <<<PHP
<?php
echo join('', file('php://stdin'));
?>
PHP
);
$cmd = "/sbin/hdparm -I /dev /sda  | sudo /usr/bin/php -f $pwd");
exec($cmd, $output, $return);
echo '<pre>' . print_r($output, true) . '</pre>';

and edit /etc/sudoers to add the following line. replace the reference to FILENAME with the value of the $pwd variable above (i.e the absolute path to the pwd.php file in the current working directory). and of course if php is not in /usr/bin/php change that reference too

apache    ALL=(ALL) NOPASSWD: /usr/bin/php -f FILENAME

that should then allow the command to be run with root privileges.

 

[proggybilly]

Thanks, I will give that a try today and let you know how it goes.

 

[proggybilly]

jpadie,
I am confused with the code you exampled. is that a seperate php file or do I put that in my current php file?

 

[jpadie]

i don't know what your current stuff is. this is a file in itself which will output the results from calling hdparm

prove that the concept works, then adapt it to your circumstances.

 

[proggybilly]

Basically I have a page that I am getting the results of ifconfig, uname -a, and df. I tried getting hdparm, but it would not display anything.I tried a few options, one being a bash script that I called from php.

 

[proggybilly]

I tried your idea and am not getting anything. Perhaps I am creating the wrong kind of file. Should this be a PHP file or a regular text file?

 

[proggybilly]

bump

 

[jpadie]

it's a php file.

the key thing is to make sure that your web service is in the sudoers file. Of course, this is not a safe thing to do...

if your web service is not called apache, substitute as required.

 

[IPGuru]

it would be prudent to adjust the change in the sudoer's file to only allow apache to run the required commands not all

 

[jpadie]

I agree with IPGuru. That is why the example I provided above limits the use of the non-passworded sudoer access to that particular command (hdparm)

 

[proggybilly]

I guess I was confused as I have never seen a php file constructed that way. I still am not getting something right, and I am frustrated. I am ready to scrap this whole thing! I created a php file with the example you provided. I called it test.php. my $pwd line looks like this $pwd = $cwd . '/var/

http://www/html/ivrconfig/pwd.php';

I set up that path in sudoers

When I call test.php, it does nothing but it does display this on my screen:

$cwd = realpath('.'); $pwd = $cwd . '/var/[URL unfurl="true"]www/html/ivrconfig/pwd.php'[/URL] file_put_contents($pwd, <<

 .print_r($output, true) . '

';

I thought this would be a simple procedure, or rather my boss did. Considering he does no PHP coding he knows not what is easy and what isn't.

 

[jpadie]

ok. let's simplify this.

1. create a password file

<?php
echo join('', file('php://stdin'));
?>

2. now create the actual executing script

$pwd = '/var/[URL unfurl="true"]www/html/ivrconfig/pwd.php';[/URL]
$cmd = "/sbin/hdparm -I /dev/hda  | sudo /usr/bin/php -f $pwd");
exec($cmd, $output, $return);
echo '<pre>' . print_r($output, true) . '</pre>';

note the following:
A. you must make sure that hdparm is in the /sbin directory or else change the command accordingly.
B. you must make sure that the php executable is in the /usr/bin directory or else change the command accordingly.

3. now change the sudoers file

apache    ALL=(ALL) NOPASSWD: /usr/bin/php -f /var/[URL unfurl="true"]www/html/ivrconfig/pwd.php[/URL]

Notes:
A. substitute 'apache' with whatever user credentials the web process runs as
B. change the reference to /usr/bin/php as necessary for the location of the php executable

 

[proggybilly]

ok, did what you said and this is what display's

Array
(
)


my sudoers file looks like this:

asterisk ALL = NOPASSWD: /usr/bin/php -f /var/

http://www/html/ivrconfig/pwd.php

This is a centos system running trixbox and asterisk. Asterisk is the user that everything runs as.

asterisk ALL = NOPASSWD: /sbin/shutdown
asterisk ALL = NOPASSWD: /usr/bin/nmap
asterisk ALL = NOPASSWD: /usr/bin/yum
asterisk ALL = NOPASSWD: /bin/chown
asterisk ALL = NOPASSWD: /bin/chmod
asterisk ALL = NOPASSWD: /bin/touch
asterisk ALL = NOPASSWD: /sbin/service
asterisk ALL = NOPASSWD: /sbin/init
asterisk ALL = NOPASSWD: /sbin/route
asterisk ALL = NOPASSWD: /bin/hostname
asterisk ALL = NOPASSWD: /bin/ln
asterisk ALL = NOPASSWD: /bin/bash
asterisk ALL = NOPASSWD: /bin/mv
asterisk ALL = NOPASSWD: /usr/sbin/amportal
asterisk ALL = NOPASSWD: /bin/cp
asterisk ALL = NOPASSWD: /bin/tar
asterisk ALL = NOPASSWD: /bin/rm
asterisk ALL = NOPASSWD: /bin/mkdir
asterisk ALL = NOPASSWD: /sbin/fdisk
asterisk ALL = NOPASSWD: /usr/bin/php
asterisk ALL = NOPASSWD: /bin/netstat
asterisk ALL = NOPASSWD: /usr/sbin/postconf
asterisk ALL = NOPASSWD: /usr/sbin/postmap
asterisk ALL = NOPASSWD: /usr/sbin/postfix
asterisk ALL = NOPASSWD: /usr/bin/crontab
asterisk ALL = NOPASSWD: /usr/bin/php -f /var/

http://www/html/ivrconfig/pwd.php

There must be something I am doing wrong or this system just doesn't have all it needs.