On Thu, Mar 10, 2022 at 08:01:53AM -0500, Michael S. Tsirkin wrote:
On Thu, Mar 10, 2022 at 09:54:24PM +0900, Jiyong Park wrote:
When iterating over sockets using vsock_for_each_connected_socket, make
sure that a transport filters out sockets that don't belong to the
transport.
There actually was an issue caused by this; in a nested VM
configuration, destroying the nested VM (which often involves the
closing of /dev/vhost-vsock if there was h2g connections to the nested
VM) kills not only the h2g connections, but also all existing g2h
connections to the (outmost) host which are totally unrelated.
Tested: Executed the following steps on Cuttlefish (Android running on a
VM) [1]: (1) Enter into an `adb shell` session - to have a g2h
connection inside the VM, (2) open and then close /dev/vhost-vsock by
`exec 3< /dev/vhost-vsock && exec 3<&-`, (3) observe that the adb
session is not reset.
[1] https://android.googlesource.com/device/google/cuttlefish/
Fixes: c0cfa2d8a788 ("vsock: add multi-transports support")
Signed-off-by: Jiyong Park <jiyong@xxxxxxxxxx>
---
drivers/vhost/vsock.c | 4 ++++
net/vmw_vsock/virtio_transport.c | 7 +++++++
net/vmw_vsock/vmci_transport.c | 5 +++++
3 files changed, 16 insertions(+)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 37f0b4274113..853ddac00d5b 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -722,6 +722,10 @@ static void vhost_vsock_reset_orphans(struct sock *sk)
* executing.
*/
+ /* Only handle our own sockets */
+ if (vsk->transport != &vhost_transport.transport)
+ return;
+
/* If the peer is still valid, no need to reset connection */
if (vhost_vsock_get(vsk->remote_addr.svm_cid))
return;
We know this is incomplete though. So I think it's the wrong thing to do
when you backport, too. If all you worry about is breaking a binary
module interface, how about simply exporting a new function when you
backport. Thus you will have downstream both:
void vsock_for_each_connected_socket(void (*fn)(struct sock *sk));
void vsock_for_each_connected_socket_new(struct vsock_transport *transport,
void (*fn)(struct sock *sk));
and then upstream we can squash these two patches.
Hmm?
Yep, reading more of the kernel documentation [1] it seems that upstream
we don't worry about this.
I agree with Michael, it's better to just have the final patch upstream
and downstream will be handled accordingly.
This should make it easier upstream to backport into stable branches
future patches that depend on this change.
Thanks,
Stefano
[1]
https://www.kernel.org/doc/Documentation/process/stable-api-nonsense.rst
