[TUHS] Who's behind the UNIX filesystem permission implementation

[Clem Cole]

FWIW: Before TOPS, there was MIT's CTSS.   The DEC Project, Programmer
Number (a.k.a. PPN) idea seems to have been similar to the People and *Problem
Number* idea of CTSS, which allowed for directories of your own files and
as well as your group (shared problem number). As Rodrigo pointed out
Multics also had a form of ACLs (UNIX used ACL's just very simplified ones).

So I'm not sure where to pin this specific idea.  I think it was a bit like
a lot of CS ideas, different people were playing with different aspects of
different ideas at the time, and brillance of Ken and Dennis was putting
some of the *best ideas *of the day *together* and adding a few of their
own into a simple implementation that was good enough to do real work.

Clem


On Wed, Jul 31, 2019 at 1:29 PM Arthur Krewat <krewat at kilonet.net> wrote:

> On 7/31/2019 12:49 PM, Rodrigo G. López wrote:
> > Multics had modes per file (https://multicians.org/fjcc4.html) but i
> > don't know about the origins. the simpler approach of
> > owner/group/other is a purely Unix creation and i would bet Ken
> > Thompson is behind it all.
>
> TOPS-10 had a 3 octal digit file protection code:
>
> <xxx> - <Owner, Project, Everyone else> - Logins are PPNs - [Project,
> Programmer] - So if I was [76,5], another user with [76,10] was in the
> same project. Much like UNIX groups.
>
> Owner Protection Codes
> 7*, 6* - You can execute, read, or change the protection code of the file.
> 5* - You have unlimited access to the file, except for renaming it.
> 4* - You have unlimited access to the file.
> 3 - You can execute, read, or change the protection code of the file.
> 2 - You have unlimited access to the file, except for renaming it.
> 1, 0 - You have unlimited access.
> * The File Daemon is called on a protection failure on this file (my
> memory is a little fuzzy on this, but I believe it allowed finer grained
> protections).
>
> Protection Codes for Fields 2 and 3
> 7 - The user cannot access the file.
> 6 - The user can only execute the file.
> 5 - The user can execute or read the file.
> 4 - The user can execute, read, or append to the file.
> 3 - The user can execute, read, append to, or update the file.
> 2 - The user can execute, read, append to, update, and write to the file.
> 1 - The user can execute, read, append to, update, write to, and rename
> the file.
> 0 - Unlimited access, including changing the protection code of the file.
>
> The name TOPS-10 was first used in 1970, but the monitor itself dates
> back to 1964. I'm not sure when these protection codes came into being,
> though.
>
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