How to execute commands in php under apache

There is no easy way - some cgi wrappers are available, I would do mine(see below)
- php has to be called from cgi
- the small wrapper will actually execute your php script

1. make this small c program called cgiwrapper.c
To get the user id of php for instance, do
grep php /etc/passwd
This is the first number, e.g.
php:x:123:...
Below uid_for_php would be 123

-------------
#include <unistd.h>
char *prog="pathtoyourphp";
main (int argc, char **argv)
{
   argv[0] = prog;
   setuid (uid_for_php);
   execv(*argv, argv);
}
-------------

2. compile and set attributes as root (cgiwrapper should be either in your cgi-bin dir (called by apache directly) or called by your actual apache cgi

# you are root...
gcc -O2 cgiwrapper.c -o cgiwrapper
# just in case
chown root cgiwrapper
# set the setuid bit
chmod 4755 cgiwrapper

When cgiwrapper is called, user becomes uid_for_php and it calls 'prog' giving the arguments initially given to cgiwrapper.

3. to test your wrapper

# Put something like '/bin/bash' in 'prog' in your .c program (replace pathtoyourphp)
# recompile , set access rights as 2. above
# just be yourself :)  (under your own id, eg. parturi)
# do
./cgiwrapper
# you should have opened a new bash ... do
id
# you should see your php id (123) for "uid="

After the test, update your cgiwrapper.c again with the actual php program/script to be run in 'prog', and step 2. again


Some people don't like much to have a setuid-program... this one is very simple and short.
The worst that could happen is executing something as 'php' user... not worse than with 'apache' user ;-)

you could give the user "apache" root access - probably not a good idea, but would work

or you could give "777" permission to whatever folders that "apache" needs to modify/work in

another thing you might consider trying is running an excpect script, have the script log in as a higher priority user, perform whatever commands need to be performed, then log out.

Thanks for answering guys!

philjones85, I won't want 777 permissions to whatever folder is going to be modified. And giving apache root access is extreme dangerours, and even if I want to do that, I have to recompile apache, by default apache won't let you do that. The other suggestion, I don't understand, I am very new at linux-apache.

Mercantilum, I have a couple of questions regarding your option (which I think it could be a solution) if I understood well what it does.

>> - php has to be called from cgi

Supouse I do a form. It means I will have to set the action to the cgi, and set the cgi to call the php page?

>>1. make this small c program called cgiwrapper.c
>>To get the user id of php for instance, do
>>grep php /etc/passwd
>>This is the first number, e.g.
>>php:x:123:...
>>Below uid_for_php would be 123

is it the same uid as if I type the comand "id root" ? because I don't have the user php in /etc/passwd, I just used that file to add protected web directories.

uid_for_php which you set it in the example as 123, it must be the uid for root in order to execute commands as root?

This script wil take arguments and pass them to the php page? which one will be executed with the uid I set?

Sorry if I do stupid question, but I can't understand very well "concepts" yet, I am coming from a windows enviroment, so.. understand me :))

based on the effort, I will give you more points.

Thank you very much!
Pablo

Mercantilum, I told you I will give you more points. When I close the question, I wasn't able to do it. I am going to ask some more things here! Thanks again