[PATCH] SYSV IPC ABI rototill

[Alfred Perlstein]

* John Baldwin <jhb at freebsd.org> [090624 07:23] wrote:
> On Tuesday 23 June 2009 7:05:01 pm Alfred Perlstein wrote:
> > * John Baldwin <jhb at freebsd.org> [090623 14:07] wrote:
> > > On Tuesday 23 June 2009 4:52:09 pm Dag-Erling Sm??rgrav wrote:
> > > > John Baldwin <jhb at freebsd.org> writes:
> > > > > There have been a several issues with the existing ABI of the SYSV IPC 
> > > > > structures over the past several years and it has been on the todo list for 
> > > > > at least both 7.0 and 8.0.  Rather than putting it off until 9.0 I sat down 
> > > > > and worked on it this week.
> > > > 
> > > > Have you given any thought to virtualization, i.e. separate namespaces
> > > > for each jail?  Will your patch make this any easier or harder to
> > > > implement?
> > > 
> > > It likely has zero effect on that.  The global variables one would need to
> > > virtualize are unchanged by this.
> > 
> > John, would it make sense to check for overflow in ipcperm_new2old and return
> > some error so that callers get back some nasty error so that they don't make
> > a mistake about permissions when an overflow happens?
> > 
> > A crash/error sounds better than silent truncating of credential information,
> > but I could be wrong.
> 
> Hmm, well, the truncation is what we have been doing all along for any users
> who used UIDs > USHRT_MAX, so adding an error now would change the behavior
> for existing binaries.  Also, the truncation does not affect the actual
> permission checks (those are all done in the kernel), merely the reporting of
> the associated IDs to userland.

OK, thank you for explaining.

-- 
- Alfred Perlstein