[RFC PATCH 0/2] Add AF_VSOCK support to getnameinfo(3) and getaddrinfo(3)

[Stefan Hajnoczi]

On Thu, Oct 06, 2016 at 01:19:00PM +0200, Florian Weimer wrote:
> On 09/30/2016 01:10 PM, Stefan Hajnoczi wrote:
> > On Thu, Sep 29, 2016 at 03:25:55PM +0200, Florian Weimer wrote:
> > > * Stefan Hajnoczi:
> > > 
> > > > Many existing programs use getnameinfo(3) and getaddrinfo(3).
> > > > Porting programs to support AF_VSOCK is easy if the library
> > > > functions can handle this address family.  Without support in glibc
> > > > each program needs to duplicate address parsing code and it becomes
> > > > harder to port programs.
> > > 
> > > What has changed since the previous discussion?
> > > 
> > >   <https://sourceware.org/ml/libc-help/2015-08/msg00004.html>
> > > 
> > > How do you expect that applications will know that they have to pass
> > > AF_VSOCK to getaddrinfo instead of AF_UNSPEC?
> > 
> > For example ncat(1) has --unixsock and --udp command-line options.  A
> > --vsock option can be added.  At that point the program knows to use
> > AF_VSOCK and the same getaddrinfo(3) code path can be used by TCP, UDP,
> > UNIX, and vsock.
> 
> ncat doesn't use getaddrinfo AFAICS, so this isn't going to help it. The
> larger nmap codebase has a call to getaddrinfo, but the code leading to it
> assumes 16-bit port numbers, so it won't be able to use getaddrinfo either.
> 
> Do you have a better example?

I just sent nfs-utils patches for mount.nfs(8):
https://marc.info/?l=linux-nfs&m=147583470431780&w=2

The nfs-utils code passes around a struct addrinfo pointer obtained by
getaddrinfo(3) from nfs_try_mount().

If getaddrinfo(3) supports .ai_family = AF_VSOCK then it's easy to reuse
the existing code without adding special cases for AF_VSOCK.

> Is there a test guest system which has NFS over AF_VSOCK running?

Sure, I can set something up for you.

> It looks
> to me that AF_VSOCK is fundamentally insecure, and I'm not sure if it can be
> fixed.

In what way?
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