[HACKERS] semaphore usage "port based"?

[Peter Jeremy]

On Mon, 2006-Apr-03 08:19:00 -0400, Daniel Eischen wrote:
>I don't really see what the problem is.  ESRCH seems perfectly
>reasonable for trying to kill (even sig 0) a process from a
>different jail.  If you're in a jail, then you shouldn't have
>knowledge of processes from other jails.

I agree in general.  The problem here is that SysV IPC isn't
jail-aware - there's a single SysV IPC address space across the
physical system.  This confuses (eg) postgres because it can
see the SHM for a postgres instance in another jail but kill(2)
claims that the process associated with that SHM doesn't exist.

There appear to be two solutions:
1) Add a sysctl to change cr_cansignal() and/or prison_check() to
   make processes visible between jails.
2) Change SysV IPC to be jail-aware.

The former is trivial - but has a number of security implications.
The latter is much harder, there is apparently a RELENG_4 patch in
kern/48471 but it's not clear how much work would be necessary to
being it up to scratch.

-- 
Peter Jeremy