history is hard
elson at pico-systems.com
Sun May 31 10:04:53 CDT 2020
On 05/31/2020 02:06 AM, jim stephens via cctalk wrote:
> On 5/30/2020 11:15 PM, Eric Smith via cctalk wrote:
>> On 05/29/2020 02:38 PM, Noel Chiappa via cctalk wrote:
>>> Low-level machines did not even have storage protection
>>> keys, and on the /40 and /50 (I think) it was an option,
>>> although I'd guess almost any /50 had it installed.
> Our /50 had it and I have never seen any indication in the
> documentation for the hardware that
> indicated that it was an option.
> I don't think that either MVT or MFT would have been very
> stable without it. I certainly spent a lot of time
> studying how to get around it, and am responsible for a
> couple of SPIE patches in the MVT product
> from exploits trying to get into supervisor mode to muck
> with such.
Yes, the SPIE call as supplied from IBM was surely the
security hole big enough for 5 ocean liners abreast to steam
right through! Everybody had to patch that, and the patch
was fairly simple. But, it was a clear indication of how
LITTLE IBM thought about security. Of course, they were
thinking about banks where 3 teams reviewed code before it
ever ran on the machine, not universities where kids would
try all sorts of mischief.
> Yes, I know supervisor state isn't tied to the storage
> keys, but that was the way I went to
> try to circumvent the storage keys.
Oh, once you have the P bit set to zero, you can do
anything, such as changing the storage protection key of
your own program.
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