Re: [PATCH net-next v10 10/11] selftests/vsock: add tests for host <-> vm connectivity with namespaces

[Bobby Eshleman <bobbyeshleman@gmail.com>]

On Tue, Nov 18, 2025 at 07:15:03PM +0100, Stefano Garzarella wrote:
> On Mon, Nov 17, 2025 at 06:00:33PM -0800, Bobby Eshleman wrote:
> > From: Bobby Eshleman <bobbyeshleman@meta.com>
> > 
> > Add tests to validate namespace correctness using vsock_test and socat.
> > The vsock_test tool is used to validate expected success tests, but
> > socat is used for expected failure tests. socat is used to ensure that
> > connections are rejected outright instead of failing due to some other
> > socket behavior (as tested in vsock_test). Additionally, socat is
> > already required for tunneling TCP traffic from vsock_test. Using only
> > one of the vsock_test tests like 'test_stream_client_close_client' would
> > have yielded a similar result, but doing so wouldn't remove the socat
> > dependency.
> > 
> > Additionally, check for the dependency socat. socat needs special
> > handling beyond just checking if it is on the path because it must be
> > compiled with support for both vsock and unix. The function
> > check_socat() checks that this support exists.
> > 
> > Add more padding to test name printf strings because the tests added in
> > this patch would otherwise overflow.
> > 
> > Add vm_dmesg_start() and vm_dmesg_check() to encapsulate checking dmesg
> > for oops and warnings.
> > 
> > Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
> > ---
> > Changes in v10:
> > - add vm_dmesg_start() and vm_dmesg_check()
> > 
> > Changes in v9:
> > - consistent variable quoting
> > ---

...

> > 
> > +test_ns_diff_global_host_connect_to_global_vm_ok() {
> > +	local oops_before warn_before
> > +	local pids pid pidfile
> > +	local ns0 ns1 port
> > +	declare -a pids
> > +	local unixfile
> > +	ns0="global0"
> > +	ns1="global1"
> > +	port=1234
> > +	local rc
> > +
> > +	init_namespaces
> > +
> > +	pidfile="$(create_pidfile)"
> > +
> > +	if ! vm_start "${pidfile}" "${ns0}"; then
> > +		return "${KSFT_FAIL}"
> > +	fi
> > +
> > +	vm_wait_for_ssh "${ns0}"
> > +	oops_before=$(vm_dmesg_oops_count "${ns0}")
> > +	warn_before=$(vm_dmesg_warn_count "${ns0}")
> > +
> > +	unixfile=$(mktemp -u /tmp/XXXX.sock)
> 
> Should we remove this file at the end of this test?
> 

Conveniently, socat does both the create and destroy for us.

> > +test_ns_diff_global_host_connect_to_local_vm_fails() {
> > +	local oops_before warn_before
> > +	local ns0="global0"
> > +	local ns1="local0"
> > +	local port=12345
> > +	local dmesg_rc
> > +	local pidfile
> > +	local result
> > +	local pid
> > +
> > +	init_namespaces
> > +
> > +	outfile=$(mktemp)
> > +
> > +	pidfile="$(create_pidfile)"
> > +	if ! vm_start "${pidfile}" "${ns1}"; then
> > +		log_host "failed to start vm (cid=${VSOCK_CID}, ns=${ns0})"
> > +		return "${KSFT_FAIL}"
> > +	fi
> > +
> > +	vm_wait_for_ssh "${ns1}"
> > +	oops_before=$(vm_dmesg_oops_count "${ns1}")
> > +	warn_before=$(vm_dmesg_warn_count "${ns1}")
> > +
> > +	vm_ssh "${ns1}" -- socat VSOCK-LISTEN:"${port}" STDOUT > "${outfile}" &
> 
> Should we wait for the listener here, like we do for TCP sockets?
> (also in other place where we use VSOCK-LISTEN)

Definitely, I didn't know ss could do this.

Best,
Bobby