Delete files outside of Web dir? - php

Question

What is the solution to delete the files outside of web dir? It doesn't delete the files.
Script will be accessed via web browser (only admins).
For example:
PHP located at: /var/www/html/delete_xx_phones.php
-rwxr-xr-x 1 root root 592 Mar 13 17:18 delete_xx_phones.php
delete_xx_phones.php code look something like this:
foreach(glob("/path/004*-phone.cf") as $file) {
unlink($file);
}
Files in /path
-rw-r--r-- 1 root root 346 Mar 13 17:15 004aaaa-phone.cf
-rw-r--r-- 1 root root 346 Mar 13 17:15 004bbaa-phone.cf

Answer 1

PHP scripts often run as user other than root, as they typically are executed by httpd. Since your files are set to have write permissions only for the root user, that's not going to work out.
If you cannot permanently change the ownership or write permission of the files, you could consider writing a very short script and executing it with elevated permissions (using sudo or the suid bit) instead of calling unlink() on PHP.
For the suid approach, write a simple script in Perl (may require perl-suidperl package installed), which deletes the filename passed as an argument:
delete-file.pl:
#!/usr/bin/perl -wT
# This is VERY insecure, so if you use it, make sure you modify it
# to filter the filenames before putting the script on production
# machines
unlink $ARGV[ 0 ];
Make sure the file is owned by root (chown root delete-file.pl) and then run chmod 6711 delete-file.pl to set its SUID bit. After that the file will always execute as root.
Then in your PHP script, you'll just need to run exec( "/path/delete-file.pl $filename" ) (consider shellescapearg() for safety) and your files should start deleting.
(Note that I'm specifically using Perl here because Bash traditionally ignores the suid bit.)
If you feel more comfortable with using sudo, then just write a script similar to what is described above (Bash will work too) and just add it to /etc/sudoers. You can then do something along the lines of: exec( "/usr/bin/sudo /path/to/delete-file-script $filename" ); to run the script with elevated permissions.

Answer 2

The files aren't accessible to PHP because they belong to the root user. PHP usually runs as with the web server's user ID, or if it's running on command line, in the context of the user who called php.
Theoretically, you could do a sudo in your PHP script to forcibly delete those files, but that's very bad practice - you'd have to store the root password in the PHP script for that.
A better way would be to change the files' owner to the user PHP runs as, or chmod ing them so PHP can delete them (although that's also not really elegant because you'd make the file accessible to every user on the machine).
Depending on your situation, a cron script that runs under the root account every couple of minutes and changes the owner of those files might be a workable solution:
chown apache:apache /path/004*-phone.cf
(substitute apache:apache with your PHP user and/or group)
Of course, if you can influence how these files are created, making them the property of the right user straight away would be ideal.