I have not been able to find solid information on preferred (best practices) and/or secure methods to allow php to access config or other types of files on a linux server not contained in the public web directory or owned by the apache user so I'm hoping to find some answers here.
I am a fairly competent PHP programmer but am increasingly tasked with writing web applications (most of which are not publicly accessible via the web however) that require updating, changing or adding to config files or files generated by some service or application on the server.
For instance, I need to create a web interface that will view, add or remove entries from a /etc/mail/spamassassin/white-list.cf file owned by root.
Another scenario is that I need php to parse mime messages in /var/vmail that are owned by user vmail.
These are just a couple examples, there will be other files in locations owned by other processes/users. How can I write PHP applications that securely access and manipulate these files without opening security risks?
If I were needing to implement something like this, I would probably look at using something like sudo to fine-tune permissions. I'm not a Linux CLI expert, so I'm sure there are issues that I haven't taken into account when typing this out.
I would probably determine what tasks need to be done, and would write a separate script for each task that needs to be completed. Using sudo, I'd assign the necessary level of permissions for that script only.
Obviously, as the number of tasks increase, so would the complexity and the amount of work involved. I'm not sure how this would affect you at the moment.
Related
Just as the question says... I've read up a few articles, others says just don't do it, but yet fail to mention a safe way. I know it hazardous to give it sudo access or root, but I was thinking about running a script that has root access through root.
One post was talking about a binary wrapper, but I did not fully understand it when I attempted it and when I tried to do a search to understand I didn't find anything that explain it well.
So, what would be a good-safe way? I don't even need to have a detailed explanation. You can just point me to a good source to start reading.
Thanks.
Specs:
Ubuntu Server 14.04
EDIT:
Commands I am talking about is mkdir, rmdir with an absolute path. Create user, remove user (which is why I need root) and edit some Apache files for me.
They fail to provide a safe way because, IMHO, there isn't one. Or, to put it another way, are you confident that your code that protects the create user and add user functions is cleverer than the hackers code that tries to gain access to your system via the back door you've built?
I can't think of a good reason for a web site to create a new system-level user. Usually web applications run using system users that are created for them by an administrator. The users inside your web site only have meaning for that web site so creating a new web site user gains that user no system privileges at all. That said, it's your call as to whether you need to do it or not.
In those cases where system operations are necessary a common approach is to build a background process that carries out those actions independently of the web site. The web site and that background process communicate via anything that works and is secure - sockets, a shared database, a text file, TCP-IP, etc. That separation allows you to control what actions can be requested and build in the necessary checks and balances. Of course it's not a small job, but you're not the first person to want to do this so I'd look for an existing tool that supports this administration.
I rule a server where several users have their own webdir, set on /home/user/public_html.
Nginx is running as http.
Everything works OK, but if a php requires a file to be created, it outputs a permission error.
How may I fix this?
Is possible to tell nginx to create all files under /home/username as "username"?
Regards && TIA ^^.
Yes, this is possible. Actually it's not Nginx, it's the FastCGI PHP module which is acting as a specific user. There is a good explanation of how to setup a Debian/Ubuntu system to do that.
Additionally I would create two users and one group per account (e.g. user1, user1-www and user1-group). For FTP you can use user1/user1-group. But the FastCGI PHP module can be configured to act as user1-www/user1-group.
Now you can limit read and write access to the folders of one account.
Your clients are free to allow or forbid write access to any file or directory based on their requirements.
If a PHP process can modify PHP code, you are exposed to be hacked and sites to be manipulated. Limiting write access to data files only reduces this danger. If you are on your own I wouldn't mind but providing hosting services to other people increased your responsibility.
I'm attempting to build an application in PHP to help me configure new websites.
New sites will always be based on a specific "codebase", containing all necessary web files.
I want my PHP script to copy those web files from one domain's webspace to another domain's webspace.
When I click a button, an empty webspace is populated with files from another domain.
Both domains are on the same Linux/Apache server.
As an experiment, I tried using shell and exec commands in PHP to perform actions as "root".
(I know this can open major security holes, so it's not my ideal method.)
But I still had similar permission issues and couldn't get that method to work either.
But I'm running into permission/ownership issues when copying across domains.
Maybe a CGI script is a better idea, but I'm not sure how to approach it.
Any advice is appreciated.
Or, if you know of a better resource for this type of information, please point me toward it.
I'm sure this sort of "website setup" application has been built before.
Thanks!
i'm also doing something like this. Only difference is that i'm not making copies of the core files. the system has one core and only specific files are copied.
if you want to copy files then you have to take in consideration the following:
an easy (less secured way) is to use the same user for all websites
otherwise (in case you want to provide different accesses) - you must create a different owner for each website. you must set the owner/group for the copied files (this will be done by root).
for the new website setup:
either main domain will run as root, and then it will be able to execute a new website creation, or if you dont want your main domain to be root, you can do the following:
create a cronjob (or php script that runs in a loop under CLI), that will be executed by root. it will check some database record every 2 minutes for example, and you can add from your main domain a record with setup info for new hosted website (or just execute some script that gains root access and does it without cron).
the script that creates this can be done in php. it can be done in any language you wish, it doesn't really matter as long as it gets the correct access.
in my case i'm using the same user since they are all my websites. disadvantage is that OS won't create restrictions, my php code will (i'm losing the advantage of users/groups permissions between different websites).
notice that open_basedir can cause you some hassle, make sure you exclude correct paths (or disable it).
also, there are some minor differences between fastCGI and suPHP (i believe it won't cause you too much trouble).
I just needed to know that is it possible in php to create an ftp user, and then create folders on the server and grant ftp access to selected folders for the ftp user created.
Thanks again!
Native PHP can not do this. The task is way out of PHP's scope.
Depending on the server OS and FTP server software used, however, PHP could call some shell scripts (or WMI / PowerShell scripts on Windows) that accomplish the task. This is not trivial to set up, though, especially not if it's to be done safely (without giving the PHP process root level privileges).
The question may be better suited on Serverfault.com.
There are a few web hosting panels written in PHP that crate ftp accounts among other things so it's definitely possible.
The exact procedure depends completely on the FTP server you use. It may involve creating new Unix user accounts.
This is more an FTP or operating system question than a PHP question though as you need to shell out to do the configuration. As Pekka said you may have more luck asking on Serverfault if you include the details of your setup.
No but if I'm not mistaking you could do something like this
Create a shell script (ftp.sh) that's has SUID (make sure it's owned by root and only can be read/written by root) that creates users, sets the permissions, etc
Call the script from php
system("./ftp.sh ".escapeshellarg($newUsername)." ".escapeshellarg($newPassword))
However I'm pretty sure there are more secure/correct ways of doing this. I can definitely see this becoming a security nightmare.
The answer is "Yes" if the web process where the script runs allows changes on the FTP settings e.g adding users, group etc. either by native PHP function or additional "Shell script" and it would be "No" if the web process doesn't have access nor privilege to make changes.
I have a web based application which server's content to authenticated users by interacting with a soap server. The soap server has file's which the user's need to be able to download.
What is the best way to serve these files to users? When a user requests a file, my server will make a soap call to the soap server to pull the file and then it will serve it to the user via referencing the link to it.
The question is that these temporary files need to be cleaned up at some point and my first thought was this being a linux based system, store them in /tmp/ and let the system take care of cleanup.
Is it possible to store these files in /tmp and have apache serve them
to the user?
If apache cannot access /tmp since it is outside of the web root, potentially I could create a symbolic link to /tmp/filename within the web root? (This would require cleanup of the symbolic links though at some point.)
Suggestions/comments appreciated on best way to manage these temporary files?
I am aware that I could write a script and have it executed as a cron job on
regular intervals but was wondering if there was a way similar to presented
above to do this and not have to handle deleting the files?
There's a good chance that Apache can read the tmp directory, but that approach smells bad. My approach would be to have PHP read the file and send it to the user. Basically, you send out the appropriate HTTP headers to indicate what type of content you're sending and what name to use for the file, and then you just spit out the file with echo (for example).
It looks like there's a good discussion of this in another question:
HTTP Headers for File Downloads
An additional benefit of this approach is that it leaves you in full control because there's PHP between a user and the file. This means you can add additional security measures (e.g., time-of-day controls), pull the file from various places to distribute bandwidth usage, and so on.
[additional material]
Sorry for not directly addressing your question. If you're using PHP to serve the files, they need not reside in the Apache web root, just where Apache/PHP has file-system read access to them. Thus, you can indeed simply store them in /tmp and let the OS clean them up for you. You might want to adjust the frequency of those clean-ups, however, to keep volume at the level you want.
If you want to ensure that access is reliably denied after a period of time or a certain number of downloads, you can store tracking information in your database (e.g., a flag on the user to indicate that they've downloaded the file), and then check it with your download script and possibly deny the download. This effectively separates security of access from frequency of cleanup, two things you may want to adjust independently.
Hope that's more helpful....