On 10/19/2005 1:55 PM, Arthur T. wrote:
On 19 Oct 2005 09:34:23 -0700, in bit.listserv.ibm-main
(Message-ID:<[EMAIL PROTECTED]>) [EMAIL PROTECTED] (Walt
Farrell) wrote:
Suppose the modal application were ATTACHEd (or spawn()ed) and
control were returned to the TMP without doint a WAIT (or waitpid),
but leaving a communication channel open between the application
and the TMP; perhaps ECB semaphores, POSIX pipes, or sockets.
(I suspect the implementation of the modal EDIT is somewhat like
this.) Further line input from the TMP, CLIST, or EXEC would
be passed to the modal application, which would return messages
and status. This interaction would continue until the TMP passed
the application an END command and the application returned a
status indicating it exited.
The modal app does not return to the TMP. The app simply issues a
PUTGET to prompt and obtain a subcommand. If the app is running in a
CLIST the "get" part of the PUTGET is satisfied when the CLIST
eventually reaches something that is not a CLIST statement, but a
command, and the app gets that returned to it.
Is the CLIST "TERMIN" command considered modal? The CLIST
continues to run (sort-of) but no code in it is executed until the user
enters one of the operand commands. Any other TSO commands can be
issued, including modal ones.
Good point; I had forgotten about TERMIN. I think this processing is
different from the way the truly modal commands work, however, as they
see (and process) the input. However, as you noted, the CLIST is
suspended and does not see any input except for the input line that
terminates TERMIN mode and returns control to the CLIST.
Since the command prompt looks the same (READY), this has possible
security implications (as a trojan, for instance).
I don't see TERMIN as having much potential to act as a trojan. WRITE
and READ, on the other hand, do seem to have potential for use in trojans.
Walt Farrell, CISSP
z/OS Security Design, IBM
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