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Another Reason To Go 64-Bit

 
 
Stephen Worthington
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      03-03-2010
On Wed, 3 Mar 2010 08:59:07 +0000 (UTC), Sweetpea
<(E-Mail Removed)> wrote:

>On Wed, 03 Mar 2010 20:47:34 +1300, Stephen Worthington wrote:
>
>> On Wed, 03 Mar 2010 17:58:10 +1300, Lawrence D'Oliveiro
>> <(E-Mail Removed)_zealand> wrote:
>>
>>>In message <(E-Mail Removed)>, Stephen
>>>Worthington wrote:
>>>
>>>> I always like the way the old Burroughs B6700 mainframe I learned on
>>>> did things. It was a tagged architecture, and used hardware
>>>> descriptors for everything.
>>>
>>>It also relied on the software to enforce system protections. Get access
>>>to a compiler that could generate privileged code, and you could take
>>>over the system.

>>
>> Yes, but access to the system Algol compiler was very restricted. You
>> needed to be a sysop to run it, and if you managed to get a sysop login
>> you could do anything anyway, including designating user programs as
>> system executables. Just like root today.

>
>That's because most tasks were run by Systems Operators or Systems Administrators and not by users.


Not true. We had lots (for those days) of terminals that were used by
senior students and staff to run jobs themselves. The junior student
jobs were actually run on a special sub-OS that the staff had written
that even further restricted what access they had (SOBS = Student
Oriented Batch System, IIRC). All those jobs had to be submitted on
card decks. It was always a problem to be able to get one of the card
punch machines that allowed you to edit within a line, otherwise if
you had to use one of the old punch as you go machines you were there
for ages repunching mistakes in your typing.
 
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Stephen Worthington
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      03-03-2010
On Wed, 03 Mar 2010 22:04:41 +1300, Lawrence D'Oliveiro
<(E-Mail Removed)_zealand> wrote:

>In message <(E-Mail Removed)>, Stephen Worthington
>wrote:
>
>> On Wed, 03 Mar 2010 17:58:10 +1300, Lawrence D'Oliveiro
>> <(E-Mail Removed)_zealand> wrote:
>>
>>>In message <(E-Mail Removed)>, Stephen
>>>Worthington wrote:
>>>
>>>> I always like the way the old Burroughs B6700 mainframe I learned on
>>>> did things. It was a tagged architecture, and used hardware
>>>> descriptors for everything.
>>>
>>>It also relied on the software to enforce system protections. Get access
>>>to a compiler that could generate privileged code, and you could take over
>>>the system.

>>
>> Yes, but access to the system Algol compiler was very restricted. You
>> needed to be a sysop to run it ...

>
>Oh, really?
>
>I was told by a colleague who use Burroughs systems in his student days,
>that he was able to get hold of a tape containing such privileged software,
>and then it was just a matter of tricking the operator into mounting it for
>him to access. Once that happened, he was in.


Exactly, it required a sysop to run the job from the tape. Of course,
the sysops were busy people who made mistakes at times and could have
been fooled into loading a tape and allowing it to run jobs. And once
you have broken through the security by getting the weakest link to
fail, then you can get to do whatever you want. But in the case of
the B6700s, the weakest link was the humans, not the computer or
software architecture.

The Intel architecture was well outdated when it was invented, but
when the 8086 was born, but Intel made a useful processor that fit in
the abilities of the silicon available back then. Then IBM made the
PC and it all took off - much to my horror. IBM should have chosen a
better chip. And Intel started down the path of wanting always to
keep new chips compatible with the old ones, so now the architecture
is incredibly awful and overgrown. And Microsoft have capped that off
by making their OS even worse than the Intel architecture. It should
have all been killed off at birth, or as soon as possible afterwards,
in favour of something that was properly designed. We knew how to do
it properly well before the Wintel architecture happened.
 
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Lawrence D'Oliveiro
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      03-03-2010
In message <(E-Mail Removed)>, Matty F wrote:

> On Mar 2, 9:01 pm, Lawrence D'Oliveiro <(E-Mail Removed)_zealand>
> wrote:
>
>> In message <(E-Mail Removed)>,
>> Matty F wrote:
>>
>>> What the hell is buffer-overflow except exceedingly bad programming
>>> that we learned to totally avoid in the 1970s?

>>
>> Surprisingly tricky to avoid: see if you can figure out what this patch
>> is guarding against <http://marc.info/?l=bugtraq&m=103564944215101&w=2>.

>
> "This length field is not checked" - why ever not? Incoming data
> should always be checked if invalid data could cause a problem.


Which was not obvious for a long time.

There was also another case, where the length field was checked, but in a
way that could be defeated if certain values were passed in that triggered
integer overflow.
 
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Sweetpea
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      03-03-2010
On Wed, 03 Mar 2010 23:12:22 +1300, Stephen Worthington wrote:

>>That's because most tasks were run by Systems Operators or Systems
>>Administrators and not by users.

>
> Not true. We had lots (for those days) of terminals that were used by
> senior students and staff to run jobs themselves.


So there were certain commands that the Admins permitted users to be able to run.

Most likely little different from being able to list the contents of a directory in terms of impact on
performance.


--
"Filtering the Internet is like trying to boil the ocean"
 
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Stephen Worthington
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      03-04-2010
On Wed, 3 Mar 2010 18:23:58 +0000 (UTC), Sweetpea
<(E-Mail Removed)> wrote:

>On Wed, 03 Mar 2010 23:12:22 +1300, Stephen Worthington wrote:
>
>>>That's because most tasks were run by Systems Operators or Systems
>>>Administrators and not by users.

>>
>> Not true. We had lots (for those days) of terminals that were used by
>> senior students and staff to run jobs themselves.

>
>So there were certain commands that the Admins permitted users to be able to run.
>
>Most likely little different from being able to list the contents of a directory in terms of impact on
>performance.


The terminals had a command line just like a modern Linux one or
Windows one. It could not do any of the SysOp commands (??? prefix)
unless logged in as a SysOp user, but you could certainly compile and
run programs. There was a job queue - if the B6700 was busy, your job
might have to wait several minutes in the queue before it ran.
Fortunately, you could just put a big job in the low priority queue
and collect the results later.
 
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Sweetpea
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      03-04-2010
On Thu, 04 Mar 2010 13:01:49 +1300, Stephen Worthington wrote:

> The terminals had a command line just like a modern Linux one or Windows
> one. It could not do any of the SysOp commands (??? prefix) unless
> logged in as a SysOp user, but you could certainly compile and run
> programs.


Entering any "command" that isn't a function of the shell runs a program.

Even on a Unix box today some commands a user can run, and some commands are restricted to the
root user.


--
"Filtering the Internet is like trying to boil the ocean"
 
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Lawrence D'Oliveiro
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      03-04-2010
In message <(E-Mail Removed)>, Stephen Worthington
wrote:

> The terminals had a command line just like a modern Linux one or
> Windows one.


Windows one, maybe, Linux one, no.
 
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