* [TUHS] v5 and v6 kernel is mode 777
@ 2015-02-22 19:50 Noel Chiappa
2015-02-22 20:01 ` Dave Horsfall
0 siblings, 1 reply; 9+ messages in thread
From: Noel Chiappa @ 2015-02-22 19:50 UTC (permalink / raw)
> From: Mark Longridge
> There's no reason for it to be mode 777 is there?
Not that I know of. Once UNIX has booted, it has no use for 'unix' (or
whatever file it booted from), and the boot loader doesn't even read the mode.
I think I habitually set mine to 644. (The 'execute' bits are, of course,
pointless...)
Noel
^ permalink raw reply [flat|nested] 9+ messages in thread
* [TUHS] v5 and v6 kernel is mode 777
2015-02-22 19:50 [TUHS] v5 and v6 kernel is mode 777 Noel Chiappa
@ 2015-02-22 20:01 ` Dave Horsfall
2015-02-23 5:31 ` Ed Carp
0 siblings, 1 reply; 9+ messages in thread
From: Dave Horsfall @ 2015-02-22 20:01 UTC (permalink / raw)
On Sun, 22 Feb 2015, Noel Chiappa wrote:
> > There's no reason for it to be mode 777 is there?
>
> Not that I know of. Once UNIX has booted, it has no use for 'unix' (or
> whatever file it booted from), and the boot loader doesn't even read the
> mode.
Didn't "ps" try and read its symbol table? I had fun days when I booted,
say, "/unix.new", and "ps" wouldn't sodding work...
--
Dave Horsfall DTM (VK2KFU) "Bliss is a MacBook with a FreeBSD server."
http://www.horsfall.org/spam.html (and check the home page whilst you're there)
^ permalink raw reply [flat|nested] 9+ messages in thread
* [TUHS] v5 and v6 kernel is mode 777
2015-02-22 20:01 ` Dave Horsfall
@ 2015-02-23 5:31 ` Ed Carp
2015-02-23 18:42 ` scj
0 siblings, 1 reply; 9+ messages in thread
From: Ed Carp @ 2015-02-23 5:31 UTC (permalink / raw)
Yes - I remember those days!
BTW, ever tried running /unix from a shell prompt? :)
On 02/22/2015 12:01 PM, Dave Horsfall wrote:
> On Sun, 22 Feb 2015, Noel Chiappa wrote:
>
>>> There's no reason for it to be mode 777 is there?
>>
>> Not that I know of. Once UNIX has booted, it has no use for 'unix' (or
>> whatever file it booted from), and the boot loader doesn't even read the
>> mode.
>
> Didn't "ps" try and read its symbol table? I had fun days when I booted,
> say, "/unix.new", and "ps" wouldn't sodding work...
^ permalink raw reply [flat|nested] 9+ messages in thread
* [TUHS] v5 and v6 kernel is mode 777
@ 2015-02-22 20:19 Noel Chiappa
0 siblings, 0 replies; 9+ messages in thread
From: Noel Chiappa @ 2015-02-22 20:19 UTC (permalink / raw)
> From: Dave Horsfall <dave at horsfall.org>
>> Once UNIX has booted, it has no use for 'unix' (or whatever file it
>> booted from)
> Didn't "ps" try and read its symbol table?
Sorry, meant 'UNIX the monolithic kernel'; yes, ps and siblings (e.g. iostat)
need to get the running system's symbol table.
> I had fun days when I booted, say, "/unix.new", and "ps" wouldn't
> sodding work...
Know that feeling! I added the following to one of the kernel data files:
char *endsys &end;
and then in programs which grab the system's symbol table, I have an nlist()
entry:
"_endsys",
with the follwing code:
/* Check that the namelist applies to the current system.
*/
checknms(symfile)
char *symfile;
{ char *chkloc, *chkval;
if (nl[0].type == 0)
cerror("No namelist\n");
chkloc = nl[ENDSYS].value;
chkval = rdloc(chkloc);
if (chkval != nl[END].value) {
cerror("Symbol table in %s doesn't match running system\n",
symfile);
}
}
on the theory that pretty much any change at all is going to result in a
change in the system's size (and thus the address of 'end').
Although in a split I/D system, this may not be true (you could change the
code, and have the data+BSS remain the same size); I should probably check
the location of 'etext' as well...
Anyway, a rebuilt system may result in the address of 'endsys' changing, and
thus the rdloc() won't return the contents of the running system's 'endsys',
but the chances of an essentially-random fetch being the same as the value of
'end' in /unix are pretty slim, I would say...
Noel
^ permalink raw reply [flat|nested] 9+ messages in thread
* [TUHS] v5 and v6 kernel is mode 777
@ 2015-02-22 19:36 Mark Longridge
2015-02-22 19:49 ` Ronald Natalie
2015-02-22 19:56 ` Dave Horsfall
0 siblings, 2 replies; 9+ messages in thread
From: Mark Longridge @ 2015-02-22 19:36 UTC (permalink / raw)
I just had it brought to my attention that the unix kernel is mode 777
in Unix v5 and v6:
ls -l /unix
-rwxrwx 1 root 27066 Mar 23 1975 /unix
There's no reason for it to be mode 777 is there? It seems rather dangerous.
In Unix v7 it defaults to mode 775 and in 32v it is 755. I figure it
setting it to mode 755 will work and so far it seems fine in v5.
Mark
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2015-02-23 18:42 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
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2015-02-22 19:50 [TUHS] v5 and v6 kernel is mode 777 Noel Chiappa
2015-02-22 20:01 ` Dave Horsfall
2015-02-23 5:31 ` Ed Carp
2015-02-23 18:42 ` scj
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2015-02-22 20:19 Noel Chiappa
2015-02-22 19:36 Mark Longridge
2015-02-22 19:49 ` Ronald Natalie
2015-02-22 20:30 ` Mark Longridge
2015-02-22 19:56 ` Dave Horsfall
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