On Fri, Jan 24, 2020 at 03:08:18AM +0000, Sunil Muthuswamy wrote:
> commit c742c59e1fbd ("hv_sock: Remove the accept port restriction")
>
> Currently, hv_sock restricts the port the guest socket can accept
> connections on. hv_sock divides the socket port namespace into two parts
> for server side (listening socket), 0-0x7FFFFFFF & 0x80000000-0xFFFFFFFF
> (there are no restrictions on client port namespace). The first part
> (0-0x7FFFFFFF) is reserved for sockets where connections can be accepted.
> The second part (0x80000000-0xFFFFFFFF) is reserved for allocating ports
> for the peer (host) socket, once a connection is accepted.
> This reservation of the port namespace is specific to hv_sock and not
> known by the generic vsock library (ex: af_vsock). This is problematic
> because auto-binds/ephemeral ports are handled by the generic vsock
> library and it has no knowledge of this port reservation and could
> allocate a port that is not compatible with hv_sock (and legitimately so).
> The issue hasn't surfaced so far because the auto-bind code of vsock
> (__vsock_bind_stream) prior to the change 'VSOCK: bind to random port for
> VMADDR_PORT_ANY' would start walking up from LAST_RESERVED_PORT (1023) and
> start assigning ports. That will take a large number of iterations to hit
> 0x7FFFFFFF. But, after the above change to randomize port selection, the
> issue has started coming up more frequently.
> There has really been no good reason to have this port reservation logic
> in hv_sock from the get go. Reserving a local port for peer ports is not
> how things are handled generally. Peer ports should reflect the peer port.
> This fixes the issue by lifting the port reservation, and also returns the
> right peer port. Since the code converts the GUID to the peer port (by
> using the first 4 bytes), there is a possibility of conflicts, but that
> seems like a reasonable risk to take, given this is limited to vsock and
> that only applies to all local sockets.
>
> Signed-off-by: Sunil Muthuswamy <sunilmut@xxxxxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> ---
> net/vmw_vsock/hyperv_transport.c | 68 +++++---------------------------
> 1 file changed, 9 insertions(+), 59 deletions(-)
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
