Paul Gilmartin wrote:
On Sat, 21 Oct 2006 15:44:00 -0600, Jeffrey D. Smith <[EMAIL PROTECTED]> wrote:
LA R3,FUBAR
ST R2,0(0,R3)
No way for the assembler to determine that the ST is storing
into field FUBAR.
The only way to know for sure is to put the program into
read-only storage. An unauthorized program can do that by
using the IARVSERV or PGSER to page protect the program
after it is loaded. The program must be marked page-aligned
and the size must be an exact multiple of a page.
There has also been discussed on ASSEMBLER-LIST a secret PARMLIB
option that when set causes all code, authorized or not, marked
RENT to be loaded in a write-protected subpool. There was a URL
for an IBM presentation.
Write-protected subpools?! No such thing!
I mentioned the CsvRentSp252 DIAG trap earlier in this thread.. What
that does is put RENT code into subpool 252, which is key zero storage.
Therefore, programs running in PSW key zero can modify SP 252 storage.
To get complete protection of all RENT modules, you must use the
CsvRentProtect DIAG trap. That uses PGSER PROTECT to protect the modules
once they're loaded. I don't recommend that setting on systems older
than z/OS V1R8 because there are several popular IBM programs, residing
in SP 252, that "legitimately" update themselves and whose module names
don't appear in the exception table until that release.
[Disclaimer: DIAG traps are not intended for use on production systems.]
--
Edward E Jaffe
Phoenix Software International, Inc
5200 W Century Blvd, Suite 800
Los Angeles, CA 90045
310-338-0400 x318
[EMAIL PROTECTED]
http://www.phoenixsoftware.com/
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