Re: [RFC PATCH 0/2] net: connect to UNIX sockets from specified root

[Stanislav Kinsbursky]

13.08.2012 20:47, J. Bruce Fields ÐÐÑÐÑ:
> On Sat, Aug 11, 2012 at 03:15:24PM +0400, Stanislav Kinsbursky wrote:
> > 11.08.2012 10:23, Pavel Emelyanov ÐÐÑÐÑ:
> > > On 08/11/2012 03:09 AM, H. Peter Anvin wrote:
> > > > On 08/10/2012 12:28 PM, Alan Cox wrote:
> > > > > Explicitly for Linux yes - this is not generally true of the AF_UNIX
> > > > > socket domain and even the permissions aspect isn't guaranteed to be
> > > > > supported on some BSD environments !
> > > > Yes, but let's worry about what the Linux behavior should be.
> > > >
> > > > > The name is however just a proxy for the socket itself. You don't even
> > > > > get a device node in the usual sense or the same inode in the file system
> > > > > space.
> > > > No, but it is looked up the same way any other inode is (the difference
> > > > between FIFOs and sockets is that sockets have separate connections,
> > > > which is also why open() on sockets would be nice.)
> > > >
> > > > However, there is a fundamental difference between AF_UNIX sockets and
> > > > open(), and that is how the pathname is delivered.  It thus would make
> > > > more sense to provide the openat()-like information in struct
> > > > sockaddr_un, but that may be very hard to do in a sensible way.  In that
> > > > sense it perhaps would be cleaner to be able to do an open[at]() on the
> > > > socket node with O_PATH (perhaps there should be an O_SOCKET option,
> > > > even?) and pass the resulting file descriptor to bind() or connect().
> > > I vote for this (openat + O_WHATEVER on a unix socket) as well. It will
> > > help us in checkpoint-restore, making handling of overmounted/unlinked
> > > sockets much cleaner.
> > I have to notice, that it's not enough and doesn't solve the issue.
> > There should be some way how to connect/bind already existent unix
> > socket (from kernel, at least), because socket can be created in
> > user space.
> > And this way (sock operation or whatever) have to provide an ability
> > to lookup UNIX socket starting from specified root to support
> > containers.
> I don't understand--the rpcbind sockets are created by the kernel.  What
> am I missing?

Kernel preform connect to rpcbind socket (i.e. user-space binds it), 
doesn't it?

> --b.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/