On 2014-11-17, at 08:05, Tom Marchant wrote: > On Fri, 14 Nov 2014 18:31:23 -0500, Farley, Peter x23353 wrote: > >> I have often thought it was a mistaken design by IBM that prohibits >> non-authorized programmers from exploiting multiple address spaces >> and instruction-level space-switching facilities. > > How would you propose that such non-authorized programs access only > the other address spaces that they were permitted to access? In other > words, how would you protect the integrity of all address spaces if > unauthorized code were able to access other address spaces? > fork() allows programmers to exploit multiple address spaces. It requires no elevated privileges. I presume it protects integrity.
[Restored from trimmage]: >> ... Or for that matter, the machine-level I/O facilities. >> I believe that was much the design of original S/360 I/O, with user-written channel programs prefixed by the OS to ensure security. This led to Byzantine code to support byte-spinning and dynamically modified channel programs. To the extent that it's gone, good riddance. -- gil
