[Info-vax] Android development Was Re: OT: Larry Ellison takes retirement as CEO of Oracle

[VAXman- at SendSpamHere.ORG]

In article <5421c8f7$0$41742$c3e8da3$5d8fb80f at news.astraweb.com>, JF Mezei <jfmezei.spamnot at vaxination.ca> writes:
>On 14-09-23 14:20, John Reagan wrote:
>
>> SYS$QIO (and all system services) are specially known to the linker/image activator (called the public vectors).
>
>Would it be correct to state that the image activator would simply stick
>the address of SYS$QIO entry point in the loaded executable ?
>
>> Privilege checks are performed by the services against the process' current privs.
>
>But surely system services perform operations that would not be
>permitted if done by the user application that only has no special privs ?
>
>So, when my user code takes the address of SYS$QIO furnished by the
>image activator and does a "CALL" instruction to it, what happens to
>allow my process (without privs) to be able to perform privileged
>operations because the code resides in area of memory that contains
>system services code ?
>
>Put it another way: if I were to take the exact same
>instructions/arguments located in the SYS$QIO system service and run
>them inside my process, it would not have the required privileges and
>fail, right ? So what happens to magically grant the same code
>privileges when I branch to a certain area of memory ?

I'm pretty sure you wouldn't get but a few instructions before you received
an ACCVIO because those instructions were attempting to modify kernel owned
memory.

-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

I speak to machines with the voice of humanity.