From 65b422d9b61ba12c08150784e8012fa1892ad03e Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Thu, 12 Nov 2020 14:38:37 +0100 Subject: vsock: forward all packets to the host when no H2G is registered Before commit c0cfa2d8a788 ("vsock: add multi-transports support"), if a G2H transport was loaded (e.g. virtio transport), every packets was forwarded to the host, regardless of the destination CID. The H2G transports implemented until then (vhost-vsock, VMCI) always responded with an error, if the destination CID was not VMADDR_CID_HOST. From that commit, we are using the remote CID to decide which transport to use, so packets with remote CID > VMADDR_CID_HOST(2) are sent only through H2G transport. If no H2G is available, packets are discarded directly in the guest. Some use cases (e.g. Nitro Enclaves [1]) rely on the old behaviour to implement sibling VMs communication, so we restore the old behavior when no H2G is registered. It will be up to the host to discard packets if the destination is not the right one. As it was already implemented before adding multi-transport support. Tested with nested QEMU/KVM by me and Nitro Enclaves by Andra. [1] Documentation/virt/ne_overview.rst Cc: Jorgen Hansen Cc: Dexuan Cui Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Reported-by: Andra Paraschiv Tested-by: Andra Paraschiv Signed-off-by: Stefano Garzarella Link: https://lore.kernel.org/r/20201112133837.34183-1-sgarzare@redhat.com Signed-off-by: Jakub Kicinski --- net/vmw_vsock/af_vsock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/vmw_vsock') diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index b4d7b8aba003..d10916ab4526 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -438,7 +438,7 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) case SOCK_STREAM: if (vsock_use_local_transport(remote_cid)) new_transport = transport_local; - else if (remote_cid <= VMADDR_CID_HOST) + else if (remote_cid <= VMADDR_CID_HOST || !transport_h2g) new_transport = transport_g2h; else new_transport = transport_h2g; -- cgit v1.2.3-59-g8ed1b