Uploaded fixes to noble and plucky unapproved queues.
** Description changed:
[Impact]
On Ubuntu VMs running under Microsoft Hyper-V, users commonly rely on
'hv_sock' (Hyper-V socket) to enable seamless SSH access using the 'hvc.exe'
tool on the Windows host. This works correctly on Ubuntu Jammy and earlier, but
fails silently in Noble, because the logic in Ubuntu's
systemd-socket-activation.patch silently rejects sockets that are not AF_INET
or AF_INET6.
Hence, when an AF_VSOCK socket is passed (which is supported by systemd
socket's ListenStream=), the client connection silently hangs.
[Test Case]
The autopkgtests for openssh contain socket-activation tests to help
avoid regressions in the existing logic. In addition to those tests, the
below manual testing will be performed to verify the AF_VSOCK fix:
+
+ Hyper-V:
1. Launch a VM on Hyper-V, and ensure the hv_sock module is loaded:
$ lsmod | grep hv_sock
2. Adding the socket conf for SSH to listen on vsock:
$ mkdir -p /etc/systemd/system/ssh.socket.d/
$ cat > /etc/systemd/system/ssh.socket.d/vsock.conf << EOF
[Socket]
ListenStream=vsock::22
EOF
$ systemctl daemon-reload
$ systemctl restart ssh.socket
3. Attempt to connect from the Hyper-V host:
hvc ssh user@ubuntu-vm
Expected Result: Connection succeeds and SSH login is presented.
Actual Result: The connection hangs.
+ Other methods:
+
+ Alternatively, this can be verified using LXD VMs.
+
+ $ lxc launch --vm ubuntu:$series test
+ $ lxc shell test
+
+ In the VM:
+
+ $ mkdir -p /etc/systemd/system/ssh.socket.d/
+ $ cat > /etc/systemd/system/ssh.socket.d/vsock.conf << EOF
+ [Socket]
+ ListenStream=vsock::22
+ EOF
+ $ systemctl daemon-reload
+ $ systemctl restart ssh.socket
+
+ Then, from the host:
+
+ $ ssh -o StrictHostKeyChecking=no -o "ProxyCommand socat - VSOCK-
+ CONNECT:$VSOCK_CID:22" ubuntu@localhost
+
+ or, if new enough to have systemd-ssh-proxy
+
+ $ ssh vsock/$VSOCK_CID
+
[Where problems could occur]
The effective goals of the patch are to (a) accept when AF_VSOCK sockets
are passed by systemd, and (b) to close() (rather than silently ignore)
unsupported socket types.
There is additional logic to properly log about where the server is
listening. This creates additional room for error.
All of the changes are contained within the setup_systemd_socket()
function. Therefore, problems would be seen when sshd is socket-
activated, e.g. on the first connection attempt to a given server.
** Changed in: openssh (Ubuntu Noble)
Status: Triaged => In Progress
** Changed in: openssh (Ubuntu Plucky)
Status: Triaged => In Progress
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https://bugs.launchpad.net/bugs/2111226
Title:
sshd socket activation does not support AF_VSOCK
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