[HECnet] How much should you be allowed to shoot yourself in the foot?

The security model in RSX is very different. Skip the rest if you don't want to know a lot of innards of RSX... There are essentially three different domains of security. 1. The first one is the terminal. A terminal have privilege, not a user. If a terminal have privilege, it can do the dangerous stuff. A terminal can, in a sense, arbitrarily gain privilege. It's just a terminal attribute like any other. Such as if you want wrapping at the right end of a line. However, of course, a non-privileged terminal do not have the privilege to turn on the privilege. But a privileged terminal can of course turn off the privilege. To re-enable it again would require someone at another terminal, with privilege, to turn it on on that terminal again. Programs that do dangerous things are usually checking against this terminal attribute to decide if it will be allowed or not. If not, you get some "nice" error message from tools that will not allow you to do stuff. 2. The second privilege domain are programs. Programs can have privilege as well. Programs that have privilege are allowed to execute system calls that are considered dangerous or affecting others. Some system calls are allowed for all users when affecting themselves, but will be denied if attempted on other users/programs, unless the program have privilege. System calls that "fail" will give an appropriate error code returned if you don't have privilege. In addition, privileged programs can map in any part of the kernel into their address space, and switch to running in kernel mode, really dropping all safe guards. So then you can shoot yourself to Jupiter in an instance, if you aren't careful. No safety net... A terminal without privilege cannot run an arbitrary program that is privileged. However, a program that have privileges, and which have already been installed in the system, can be run by anyone. So such programs have to check for themselves if the terminal is privileged, in order to decide what is allowed to do by the user (see first point above). 3. Files, as well as common regions, are protected through the concept of owners, groups, and protection masks. You essentially have SYSTEM, OWNER, GROUP and WORLD. And for each one of these groups, you can have READ, WRITE, EXTEND and DELETE access. OWNER, GROUP and WORLD should be pretty obvious, I think. However, SYSTEM is anyone with a group number of 10 or less. And these users always have the capability of changing the protection. Finally, when logging in to an RSX system, the terminal is initially always privileged. But it is also "locked", so you can't give any commands. The login system will at a point check which group you are in, and if your group number is greater than 10, it will drop the privilege of the terminal, and this happens before the terminal gets released so you can give any commands. So, in a sense, any user in group 10 or less, is a privileged user, because when they log in, they will have a privileged terminal, and they can always change protection of files they don't have access to. And they can run privileged programs, and unless those programs have some special dislike for you, you'll be able to use them to their full extent. So there is no special attributes to users, no special users, no special groups that can be added or deleted. It's just based on your terminal, which normally gets based on your UIC when you log in. The additional point is, if your terminal is privileged, you can change your UIC to whatever you want at any time. So you can become a user in whatever group you want. So, terminal privilege is pretty much enabling you to get access to everything else all the time. And when the system starts up, the console terminal is logged in, and with privilege. So unless the startup script logs that terminal out, you already have access to everything from the start. You could possibly sum things up that in RSX, if you have a privileged terminal, it's rather easy to shoot yourself in the foot, and there is very few safeguards if you write your own programs and decides you want to be creative... Johnny On 2020-10-12 23:41, Thomas DeBellis wrote: -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol