Do they exist on linux platforms?
A:
Well, DLL injection is not a Windows-specific concept, Linux can do it too, and it might be slightly simpler. (See http://en.wikipedia.org/wiki/DLL_injection). Also, IIRC the three "rings" are an x86 specific concept (not OS dependent). So to answer your question, no, none of these things is Windows specific.
krzysz00
2010-05-23 15:31:39
Rings in general aren't x86-specific, though the specific number -- four, not three btw -- varies by CPU (Dec Alpha and MIPS had just two, as these days does ARM; Multics had eight; etc, etc). Most OSs use only two levels/rings, so having four, eight, or whatever in the CPU is something of an overkill anyway;-).
Alex Martelli
2010-05-23 15:36:59
thank you for the correction
krzysz00
2010-05-23 16:02:53
A:
The ring concept is a very general one, as the wikipedia entry explains. Re Linux specifically, it says:
Linux and Windows are two operating systems that use supervisor/user-mode. To perform specialized functions, user-mode code must perform a system call into supervisor mode or even to the kernel space where trusted code of the operating system will perform the needed task and return it back to user space.
Other operating systems (as, again, the article mentions, pointing to other articles for more details) can use different security architectures (esp. capability-based ones).
Alex Martelli
2010-05-23 15:32:18
+2
A:
Rings are x86 processor architecture terminology, in which the processor can execute in one of four different operating modes called "priority levels, numbered zero to three. Priority level zero is allowed to perform any operation on the CPU, while priority level three is the most restricted - there are some instructions that cannot be executed at priority level three. Ref.
DLL injection is not specific to any operating system.
Mitch Wheat
2010-05-23 15:32:38