Security question?

Adam Jackson ajax at nwnk.net
Wed Nov 3 17:29:24 PST 2004


On Wednesday 03 November 2004 19:27, Roland Mainz wrote:
> Adam Jackson wrote:
> > getsockname(3) on the connection fd.  It's local if one of:
> >
> > - family is PF_UNIX
> > - family is PF_INET and address is 127.0.0.1
> > - family is PF_INET6 and address is ::1
> > - family is PF_DECnet and address is whatever the DECnet loopback address
> > is (probably you don't need to worry about this case)
>
> BTW: Solaris has a shared-memory transport (AFAIK HP-UX, too) ... but I
> am not sure whether this is indicated via a seperate socket family or
> just handled internally by Xlib.

SGI and DEC too.  And internal to Xlib, AFAIK, still using the PF_UNIX socket 
for synchronization.

Precision Insight did some research into adding this to XFree86 in the early 
4.0 days, but it was decided that it wasn't worth the added complexity since 
shared memory transport only really helps when the graphics subsystem is much 
more powerful than the CPU.  The original paper fell off the net, but I 
rescued it from the wayback machine:

http://dri.sourceforge.net/cgi-bin/moin.cgi/SharedMemoryTransport

It would be interesting to see if the results in this paper can be improved 
upon by using linux futexes rather than the Unix socket for synchronization.  
The implementation referred to in this paper is still available on a branch 
of the DRI xc tree, if anyone feels like some archaeology.

- ajax
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