SUMMARY: Why can't a normal user set Sticky bit ?

Date: Wed Aug 07 1991 - 03:50:10 CDT

Here is a brief summary about the usage of sticky(8)
My Question was:
We are working on an archive system which marks the file 'archived'
by zeroing it and set the sticky bit on.
Only root can do the chmod +1000 on regular files.
On our Convex C220 a user can set sticky bit on regular files
Here are some answers:
>Since day one, the sticky bit has been a root-only thing.
Yes, that what I told the Sysadmin of the convex, only directory stuff
for normal users.
>Originally, the sticky bit meant `keep this executable on swap'.
>Obviously, normal users shouldn't be allowed to do that.
>In SunOS is now means `don't use the buffer cache for this file'.
>I suppose they forgot to drop to drop the suser() check.
>There seems to be no real reason to restrict its use to the superuser.
After reading through sticky(8) and chmod(2) I got puzzled what the current
usage for bit 1000 is used for on regular files.
Casper Thanx !!! This must be the reason
>From (Barry Shein):
>(and a quick experiment shows that Sun/OS does indeed let
>anyone set the text bit on a directory they can otherwise change
>permissions on, at least it does under 4.0.3).
4.1.1. Does restrict too for normal files
>Perhaps the Convex ignores the sticky bit on executables (it's become
>somewhat antiquated as paging text directly out of file space has
>become fast enough for activation.)
As Casper mentioned, I too suspect the suser() check is the real reason why.
Demand paging is fast and there is no reason to push it into swap
Maybe it is restricted for backward compatibility.
> Or ignores/abandons it if swap
>becomes dangerously full (and like I said, it may not matter much
>really if it's ignored anyhow!)
>I believe Sun/OS still takes it fairly seriously (on executables) tho
>I haven't done any investigation lately.
Thank you all SUN MGR's
Marcel Bernards, UNIX & Net sysadm Netherlands Energy Research Foundation ECN
(and SURFnet IP/ICP), Phone: (+31 /0)2246 4579 Fax: (+31 /0)2246 1864
E-Mail: Bernards@ECN.NL, SnailMail: P.O. Box 1, 1755 ZG Petten
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