qrexec-policy: prefer using VM objects

Pass VM object instead of just name - it will make extending much
easier. For example new DispVM handling.

QubesOS/qubes-issues#2253

qrexec/qrexec-policy

@@ -103,45 +103,40 @@ def read_policy_file(service_name):
     return policy_list
 
 
-def is_match(item, config_term):
-    return (item is not "dom0" and config_term == "$anyvm") or \
-        item == config_term
-
+def is_match(config_term, item):
+    if config_term == '$anyvm':
+        # match anything but dom0
+        return item != "dom0"
+    else:
+        return config_term == item
 
 def get_default_policy():
     return {"action": "deny"}
 
 
-def find_policy(policy, domain, target):
+def find_policy(policy, source_domain, target, target_domain=None):
     for policy_iter in policy:
-        if not is_match(domain, policy_iter["source"]):
+        if not is_match(policy_iter["source"], source_domain):
             continue
-        if not is_match(target, policy_iter["dest"]):
+        if not is_match(policy_iter["dest"], target):
             continue
         return policy_iter
     return get_default_policy()
 
 
-def validate_target(target):
+def validate_target(app, target):
     # special targets
-    if target in ['$dispvm']:
+    if target == '$dispvm' or target.startswith('$dispvm:'):
         return True
 
-    app = qubes.Qubes()
-
     return app.domains[target]
 
 
 def spawn_target_if_necessary(vm):
     if vm.is_running():
         return
-    # use qvm-run instead of vm.start() to make sure that nothing is written
-    # to stdout and nothing is read from stdin
-    null = open("/dev/null", "r+")
-    subprocess.call(["qvm-run", "-a", "--tray", "-q", vm.name, "true"],
-        stdin=null, stdout=null)
-    null.close()
-
+    # TODO: tray notification
+    vm.start()
 
 def do_execute(domain, target, user, service_name, process_ident, vm=None):
     if target == "$dispvm":
@@ -153,9 +148,10 @@ def do_execute(domain, target, user, service_name, process_ident, vm=None):
         if isinstance(vm, qubes.vm.qubesvm.QubesVM):
             spawn_target_if_necessary(vm)
         if target == "dom0":
-            cmd = QUBES_RPC_MULTIPLEXER_PATH + " " + service_name + " " + domain
+            cmd = QUBES_RPC_MULTIPLEXER_PATH + " " + service_name + " " + \
+                domain.name
         else:
-            cmd = user + ":QUBESRPC " + service_name + " " + domain
+            cmd = user + ":QUBESRPC " + service_name + " " + domain.name
         # stderr should be logged in source/target VM
         null = open(os.devnull, 'w')
         os.dup2(null.fileno(), 2)
@@ -236,8 +232,20 @@ def main():
     # connection
     process_ident += "," + args.domain + "," + args.domain_id
 
+    app = qubes.Qubes()
+
     try:
-        vm = validate_target(args.target)
+        source_vm = app.domains[args.domain]
+    except KeyError:
+        print >> sys.stderr, "Rpc failed (unknown source domain): ", \
+            args.domain, args.target, args.service_name
+        text = "Domain '%s' doesn't exist (service %s called to domain %s)." % (
+            args.domain, args.target, args.service_name)
+        info_dialog("error", text)
+        return 1
+
+    try:
+        target_vm = validate_target(app, args.target)
     except KeyError:
         print >> sys.stderr, "Rpc failed (unknown domain):", \
             args.domain, args.target, args.service_name
@@ -253,7 +261,7 @@ def main():
         if policy_list is None:
             policy_list = list()
 
-    policy_dict = find_policy(policy_list, args.domain, args.target)
+    policy_dict = find_policy(policy_list, source_vm, args.target, target_vm)
 
     if policy_dict["action"] == "ask" and args.assume_yes_for_ask:
         policy_dict["action"] = "allow"
@@ -283,8 +291,9 @@ def main():
         else:
             user = "DEFAULT"
         print >> sys.stderr, "Rpc allowed:", args.domain, args.target, args.service_name
-        do_execute(args.domain, args.target, user, args.service_name, process_ident, vm=vm)
-
+        do_execute(source_vm, args.target, user, args.service_name, process_ident,
+            vm=target_vm)
+        return 0
     print >> sys.stderr, "Rpc denied:", args.domain, args.target, args.service_name
     return 1