On Wed, 14 Jul 2010 00:19:37 +0200, Rob van der Heij wrote: >But when you run a program as non-root user, there's still limits to >what you can break. And z/Linux has some lucky aspects that make it >less likely a program can acquire root privileges.
If you know of any way for a non-root program to obtain root privileges, the entire Linux/UNIX community would like to know. This simply should not be possible in the Linux/UNIX process model, even if the program is compromised with a virus. Malware is able to access or destroy only the objects to which the owner has access and it cannot switch owners. Linux/UNIX is not Windows! z/Linux does have the security advantage over most (all?) other Linux implementations that the kernel is not mapped into the user address space. But even if the kernel is visible to user processes there is still no sneaky way to acquire root privileges if the process owner does not have them. This is not luck. It is intrinsic to the design. And since this discussion has been about (semi-)privileged instructions: root is not the same as supervisor state. It is simply impossible in z/Linux for a user process (even if owned by root) to run in supervisor state. David Bond
