[tpop3d-discuss] tpop3d, sendmail and owner of mailbox

Chris Lightfoot chris at ex-parrot.com
Wed, 14 Nov 2001 12:43:39 +0000

On Wed, Nov 14, 2001 at 12:36:57PM +0000, Chris Elsworth wrote:
> On Wed, Nov 14, 2001 at 09:51:47AM +0000, Chris Lightfoot wrote:
> > The reason that mail-group can be chosen in the above way
> > is that on some systems, /var/spool/mail is group mail,
> > g+w, so that a program needs to be setgid mail to write a
> > lock file. On other systems, /var/spool/mail is 1777, a
> > far more sensible default, and anyone can write a lock
> > file into /var/spool/mail.
> Not to start an argument or anything, but I share the view that the only 
> mode 1777 directory on the entire system should be /tmp.
> Any mode 1777 directory has the potential of being filled up (by anyone 
> who wants to), thus rendering the partition useless for valid applications 
> - I could fill up the drive with any old file in /var/spool/mail if its 
> mode 1777, and from that point on, nobody gets any mail.
> Group mail, and g+w, is, in my opinion, the more sensible protection 
> scheme. Opinions will vary :)

Ah, what would be the fun of having a mailing list without
the occasional flame-war....

The counterarguments are:

    - group mail g+w means that all mail clients must be
      setgid mail in order to do locking properly, and
      therefore introduce an additional security exposure;
    - if somebody is sufficiently silly to try to fill up
      /var/spool/mail, it will be fairly obvious who is
    - suitably-configured user disk quotas make this all
      kind of irrelevant anyway.

The real solution is probably not to use dot-locking at
all, given that fcntl now (a) works and (b) is universally

 With Age comes Wisdom - but sometimes Age travels alone