[comp.mail.sendmail] problems with new users' mail file creation

diamant@hpfclp.SDE.HP.COM (John Diamant) (07/12/88)

> this is a bug in the Ultrix-sendmail. You can fix it by setting the mode
> of '/usr/spool/mail' to 1777 (don't forget the sticky bit, or everyone
> can remove your mailbox!). 

Would you care to explain that item about the sticky bit?  I always that the
sticky bit was merely an efficiency hack.  Are you saying that it actually
changes the security of the running program?  How?


John Diamant
Software Development Environments
Hewlett-Packard Co.		ARPA Internet: diamant@hpfclp.sde.hp.com
Fort Collins, CO		UUCP:  {hplabs,hpfcla}!hpfclp!diamant

lyndon@ncc.Nexus.CA (Lyndon Nerenberg) (07/15/88)

In article <1410006@hpfclp.SDE.HP.COM> diamant@hpfclp.SDE.HP.COM (John Diamant) writes:
>Would you care to explain that item about the sticky bit?  I always that the
>sticky bit was merely an efficiency hack.  Are you saying that it actually
>changes the security of the running program?  How?

In some BSD implementations, setting the sticky bit on a directory says
that (if you have the appropriate write permission) you can create a
file in that directory, however you have to be the owner of the file
in order to remove it.

We use this feature in a number of public "spool" directories where we
don't want to run an suid program soley for the purpose of protecting
files from inadvertant or malicious deletion.

[ Where did this "feature" originate, anyway ?? ]

-- 
{alberta,pyramid,uunet}!ncc!lyndon  lyndon@Nexus.CA
Ain't singin' for Miller...

robert@pvab.UUCP (Robert Claeson) (07/18/88)

In article <10331@ncc.Nexus.CA>, lyndon@ncc.Nexus.CA (Lyndon Nerenberg) writes:

> In some BSD implementations, setting the sticky bit on a directory says
> that (if you have the appropriate write permission) you can create a
> file in that directory, however you have to be the owner of the file
> in order to remove it.

AT&T has included this feature in their latest release of UNIX System V,
Release 3.2. It comes with the sticky bit set as default on /tmp and /usr/tmp.