How to Create Restricted Guest Account

noise617

Hi,

I have tried creating a guest account by adding a "standard" user in the Control Center and setting up a simple password.

I discovered that the Guest may view my, administrator's, home folder. Can this account be sandboxed, so other users' files, especially those of the administrator, are invisible to the user?
How do I remove a password for the Guest account?

WetGeek

noise617 I discovered that the Guest may view my, administrator's, home folder

I don't have an answer for you, but your post made me curious. Can the Guest just view the /root folder, or can the Guest actually access contents there?

Either way, I'm surprised that it can happen, but one is obviously much worse than the other.

WetGeek

noise617 I have tried creating a guest account by adding a "standard" user in the Control Center and setting up a simple password.

Something is definitely wrong. I created an ordinary user on my system, named "test." Then I logged on as test, and tried to access /root. All I could see was a blank page in Dolphin with the words "Folder is empty." So I could neither access anything there, I couldn't even view what was there.

Since I'm normally the only user on any of my computers, I couldn't be sure what would happen, but this is what I expected would (and should).

Have you tried deleting your Guest account and re-creating it, if you can't delete the password? What DE are you using? (I'm using Plasma. If you're not, I can try to reproduce this in a VM.)

WetGeek

noise617 I discovered that the Guest may view my, administrator's, home folder. Can this account be sandboxed, so other users' files, especially those of the administrator, are invisible to the user?

Apparently, then, the bottom line is "There's no way to do that." Not by modifying the Guest user account. But you could keep ALL standard users out of those folders by changing their permissions.

I guess you could create a group for all users who are allowed to access other user's home folders and exclude Guest from that group, but that would be a bother to arrange unless there was a really serious need for it.

EbonJaeger

WetGeek I believe they're talking about the admin account's home folder, not /

WetGeek

EbonJaeger I believe they're talking about the admin account's home folder, not /

Sorry for the confusion. I understand now. I'm the admin on my computers, but my home folder is different than /root. I'll create a test subject again, and see whether it can access my home folder.

I wouldn't expect one user to access another user's home folder, admin or not. We'll see if I got that right.

WetGeek

WetGeek I wouldn't expect one user to access another user's home folder, admin or not.

Okay, now I'm both surprised and would be concerned if I weren't the only user on this system. I created the "test" user again, and indeed, while logged on as test, I could browse to my own home folder and not only view what's there, but also access the folder's contents.

I never would have believed that's possible, until I just saw it happen with my own eyes. User "test" in no way had elevated privileges. Just one user accessing the home folder of another user, who also happens to be the admin.

I'm now very interested in the answer to @noise617's original question. Is there a way to restrict such access to an ordinary user on your system? Do you know what that answer is?

noise617

As a Guest (non-administrator user, to put it simple), I can view the root folder.

I can also view the administrator's home folder (/home/admin), and view certain files and folders. Others are marked with a cross in Nautilus.

I use a more or less default Budgie setup.

WetGeek

noise617 As a Guest (non-administrator user, to put it simple), I can view the root folder.

I was unable to do that as an ordinary user. I'm now curious enough to try this all on my Budgie VM. I'll let you know what happens there.

WetGeek

WetGeek I'll let you know what happens there.

On my Budgie VM, when logged on as "test" and trying to access /root, this is what I get:

It's possible the only files there are hidden, such as .bashrc, so I'll try that again after making sure something is there to be examined. As the "test" user, I was easily able to view the contents of the admin's home folder, though, and even open the bashrcAdditions text file there with Gedit. I could only open it read-only, though.

I was right. The first time, the folder was empty because the only file there was .bashrc, which was hidden. In the terminal, I copied bashrcAdditions from /home/jerry to /root, and tried again. This time, the "test" user was able to not only see the file, but it could open it in Gedit for read-only access.

So, I'm able to confirm what @noise617 is seeing on his system. But I'm not able to explain why one ordinary user can view the contents of another's home directory, even if that user is root. As I said, I'm very interested in how Linux can allow this to happen.

noise617

The root folder as seen by Guest:

The admin's /home folder as seen by the Guest. Note that some folders are marked with a cross:

The admin's Documents as seen by the Guest:

The admin's Music folder as seen by the Guest. I was able to playback mp3 files, too:

elfprince

You can restrict you home directory access to you only, by changing the permissions.

WetGeek

elfprince You can restrict you home directory access to you only, by changing the permissions.

That makes sense. What does't make sense is why restricted access isn't the default. Does root have to restrict access the same way?

This has been a really educational issue for me, after using Linux for all these years. I guess I've always used it on a single-user system, though, because where I've worked there's always been a Windows network. I've never had a reason to question how user security works by default on Linux.

elfprince

WetGeek A root or superuser account can view and perform any operations on a multi user unix-like os.
A user can block access, or execute, ability to his own directory by changing the 'rwx' bits in the directory's permission setting.

WetGeek

elfprince A user can block access, or execute, ability to his own directory by changing the 'rwx' bits in the directory's permission setting.

Yes. I've always known about root or SU privileges. I just assumed that one user's /home directory and its contents would be off-limits to other users except root or SU.

I'm not amazed that this can be achieved by changing the home directory's permissions, but am amazed that they're not private by default. I guess I never felt the need to check that. Seems like one should have to change the permissions to allow other users to access ones content, not to keep them out of ones home folder.

Thanks for the education!

elfprince

WetGeek Yes, the current permissions are liberal. Then again, Solus is an OS for home/personal use. Maybe that is why?

WetGeek

elfprince Then again, Solus is an OS for home/personal use. Maybe that is why?

Could be. However, I'm not sure what would be harmed by keeping home folders private by default, whether at home or at work.

Now, I'm curious whether it is a Solus default or a Linux default. If I get bored enough on this holiday weekend, I may try some different distro VMs to see how it works on them. I've got lots of .ISO files to choose from.

I guess it should be obvious that if you want to keep your private files private, you need to change the permissions on your home folder. It just wasn't all that obvious to me.

noise617

elfprince Yes, the current permissions are liberal. Then again, Solus is an OS for home/personal use. Maybe that is why?

My five cents as a regular user: I would say that, on the contrary, it would be more intuitive if a non-administrator could only view his own folder. Not other users' folders and especially not / and admin's Home.

The thinking behind this is that I create a separate user account so the guest stays sandboxed and cannot access my files. With the current settings, however, it doesn't make much sense to create another account as access rights are liberal.

elfprince

WetGeek Yes, I would be curious if other Linux distros have same ' open setup' by default.

EbonJaeger

My user account doesn't have read set for other people, but newly created accounts from system settings does have both read and execute set, regardless of if they are standard or administrator user accounts. I have no idea why that is, or where it's even set.

Pop_OS doesn't set read or any other permissions for other users on user home directories.

WetGeek

EbonJaeger Pop_OS doesn't set read or any other permissions for other users on user home directories.

That's the way I would have expected that ALL Linux systems would work. Until today, of course.

That tells me that it's a per-distro feature, not a Linux feature. You saved me from creating a bunch of non-Solus VMs to test that. Thanks!

I also suspect that the distros I used before I found Solus did keep home folders private to the user, so my previous assumptions were probably true based on my pre-Solus experience.

WetGeek

WetGeek You saved me from creating a bunch of non-Solus VMs to test that.

Although I have other things to do now, as I explore other distros in the future, this is one feature I'm going to add to my examination. This has made me curious to discover how common it is to let all users have rx access to all other users' home folders.