test: Use context system for guest commands

Extends the context system in the test scripts to allow executing commands
within a guest.  Do this without requiring an existing network in the guest
by using socat to run ssh via a vsock connection.

We do need some additional "sleep"s in the tests, because the new
faster dispatch means that sometimes we attempt to connect before
socat has managed to listen.

For now, only use this for the plain "passt" tests.  The "passt_in_ns" and
other tests have additional complications we still need to deal with.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

test/passt.mbuto

@@ -13,15 +13,15 @@
 PROGS="${PROGS:-ash,dash,bash ip mount ls insmod mkdir ln cat chmod lsmod
        modprobe find grep mknod mv rm umount jq iperf3 dhclient hostname
        sed tr chown sipcalc cut md5sum socat dd strace ping tail killall sleep
-       sysctl nproc tcp_rr tcp_crr udp_rr which tee seq bc}"
+       sysctl nproc tcp_rr tcp_crr udp_rr which tee seq bc sshd ssh-keygen}"
 
-KMODS="${KMODS:- virtio_net virtio_pci}"
+KMODS="${KMODS:- virtio_net virtio_pci vmw_vsock_virtio_transport}"
 
 LINKS="${LINKS:-
 	 ash,dash,bash		/init
 	 ash,dash,bash		/bin/sh}"
 
-DIRS="${DIRS} /tmp /sbin /var/log /var/run /var/lib"
+DIRS="${DIRS} /tmp /sbin /usr/share /var/log /var/lib /etc/ssh /run/sshd /root/.ssh"
 
 FIXUP="${FIXUP}"'
 	cat > /sbin/dhclient-script << EOF
@@ -46,7 +46,33 @@ exit 0
 EOF
 	chmod 755 /sbin/dhclient-script
 	ln -s /sbin /usr/sbin
+	ln -s /bin /usr/bin
+	ln -s /run /var/run
 	:> /etc/fstab
+
+	# sshd(dropbear) via vsock
+	cat > /etc/passwd << EOF
+root:x:0:0:root:/root:/bin/sh
+sshd:x:100:100:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
+EOF
+	cat > /etc/shadow << EOF
+root:::0:99999:7:::
+EOF
+	chmod 000 /etc/shadow
+
+	:> /etc/ssh/sshd_config
+	ssh-keygen -A
+	chmod 700 /root/.ssh
+	chmod 700 /run/sshd
+	# Alternative location for the priv separation dir
+	ln -s /run/sshd /usr/share/empty.sshd
+
+	cat > /root/.ssh/authorized_keys <<EOF
+'"$(cat guest-key.pub)"'
+EOF
+	chmod 600 /root/.ssh/authorized_keys
+	chmod 700 /root
+	socat VSOCK-LISTEN:22,fork EXEC:"sshd -i -e" 2> /var/log/vsock-ssh.log &
 	sh +m
 '