chiark / gitweb /
bus: introduce concept of "const" properties
[elogind.git] / src / libsystemd-bus / bus-objects.c
index 8413023d6f979a0bb0f0c27b3676e898cbfd050b..e468025a8189f293e6db77896968096d161edbc5 100644 (file)
@@ -19,6 +19,8 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+#include <sys/capability.h>
+
 #include "strv.h"
 #include "set.h"
 #include "bus-internal.h"
@@ -33,7 +35,8 @@ static int node_vtable_get_userdata(
                 sd_bus *bus,
                 const char *path,
                 struct node_vtable *c,
-                void **userdata) {
+                void **userdata,
+                sd_bus_error *error) {
 
         void *u;
         int r;
@@ -44,8 +47,12 @@ static int node_vtable_get_userdata(
 
         u = c->userdata;
         if (c->find) {
-                r = c->find(bus, path, c->interface, &u, u);
-                if (r <= 0)
+                r = c->find(bus, path, c->interface, u, &u, error);
+                if (r < 0)
+                        return r;
+                if (sd_bus_error_is_set(error))
+                        return -sd_bus_error_get_errno(error);
+                if (r == 0)
                         return r;
         }
 
@@ -65,7 +72,8 @@ static int vtable_property_get_userdata(
                 sd_bus *bus,
                 const char *path,
                 struct vtable_member *p,
-                void **userdata) {
+                void **userdata,
+                sd_bus_error *error) {
 
         void *u;
         int r;
@@ -75,7 +83,7 @@ static int vtable_property_get_userdata(
         assert(p);
         assert(userdata);
 
-        r = node_vtable_get_userdata(bus, path, p->parent, &u);
+        r = node_vtable_get_userdata(bus, path, p->parent, &u, error);
         if (r <= 0)
                 return r;
         if (bus->nodes_modified)
@@ -89,7 +97,8 @@ static int add_enumerated_to_set(
                 sd_bus *bus,
                 const char *prefix,
                 struct node_enumerator *first,
-                Set *s) {
+                Set *s,
+                sd_bus_error *error) {
 
         struct node_enumerator *c;
         int r;
@@ -104,9 +113,11 @@ static int add_enumerated_to_set(
                 if (bus->nodes_modified)
                         return 0;
 
-                r = c->callback(bus, prefix, &children, c->userdata);
+                r = c->callback(bus, prefix, c->userdata, &children, error);
                 if (r < 0)
                         return r;
+                if (sd_bus_error_is_set(error))
+                        return -sd_bus_error_get_errno(error);
 
                 STRV_FOREACH(k, children) {
                         if (r < 0) {
@@ -126,6 +137,8 @@ static int add_enumerated_to_set(
                         }
 
                         r = set_consume(s, *k);
+                        if (r == -EEXIST)
+                                r = 0;
                 }
 
                 free(children);
@@ -140,7 +153,8 @@ static int add_subtree_to_set(
                 sd_bus *bus,
                 const char *prefix,
                 struct node *n,
-                Set *s) {
+                Set *s,
+                sd_bus_error *error) {
 
         struct node *i;
         int r;
@@ -150,7 +164,7 @@ static int add_subtree_to_set(
         assert(n);
         assert(s);
 
-        r = add_enumerated_to_set(bus, prefix, n->enumerators, s);
+        r = add_enumerated_to_set(bus, prefix, n->enumerators, s, error);
         if (r < 0)
                 return r;
         if (bus->nodes_modified)
@@ -170,7 +184,7 @@ static int add_subtree_to_set(
                 if (r < 0 && r != -EEXIST)
                         return r;
 
-                r = add_subtree_to_set(bus, prefix, i, s);
+                r = add_subtree_to_set(bus, prefix, i, s, error);
                 if (r < 0)
                         return r;
                 if (bus->nodes_modified)
@@ -184,7 +198,8 @@ static int get_child_nodes(
                 sd_bus *bus,
                 const char *prefix,
                 struct node *n,
-                Set **_s) {
+                Set **_s,
+                sd_bus_error *error) {
 
         Set *s = NULL;
         int r;
@@ -198,7 +213,7 @@ static int get_child_nodes(
         if (!s)
                 return -ENOMEM;
 
-        r = add_subtree_to_set(bus, prefix, n, s);
+        r = add_subtree_to_set(bus, prefix, n, s, error);
         if (r < 0) {
                 set_free_free(s);
                 return r;
@@ -251,6 +266,64 @@ static int node_callbacks_run(
         return 0;
 }
 
+#define CAPABILITY_SHIFT(x) (((x) >> __builtin_ctzll(_SD_BUS_VTABLE_CAPABILITY_MASK)) & 0xFFFF)
+
+static int check_access(sd_bus *bus, sd_bus_message *m, struct vtable_member *c, sd_bus_error *error) {
+        _cleanup_bus_creds_unref_ sd_bus_creds *creds = NULL;
+        uint64_t cap;
+        uid_t uid;
+        int r;
+
+        assert(bus);
+        assert(m);
+        assert(c);
+
+        /* If the entire bus is trusted let's grant access */
+        if (bus->trusted)
+                return 0;
+
+        /* If the member is marked UNPRIVILEGED let's grant access */
+        if (c->vtable->flags & SD_BUS_VTABLE_UNPRIVILEGED)
+                return 0;
+
+        /* If we are not connected to kdbus we cannot retrieve the
+         * effective capability set without race. Since we need this
+         * for a security decision we cannot use racy data, hence
+         * don't request it. */
+        if (bus->is_kernel)
+                r = sd_bus_query_sender_creds(m, SD_BUS_CREDS_UID|SD_BUS_CREDS_EFFECTIVE_CAPS, &creds);
+        else
+                r = sd_bus_query_sender_creds(m, SD_BUS_CREDS_UID, &creds);
+        if (r < 0)
+                return r;
+
+        /* Check have the caller has the requested capability
+         * set. Note that the flags value contains the capability
+         * number plus one, which we need to subtract here. We do this
+         * so that we have 0 as special value for "default
+         * capability". */
+        cap = CAPABILITY_SHIFT(c->vtable->flags);
+        if (cap == 0)
+                cap = CAPABILITY_SHIFT(c->parent->vtable[0].flags);
+        if (cap == 0)
+                cap = CAP_SYS_ADMIN;
+        else
+                cap --;
+
+        r = sd_bus_creds_has_effective_cap(creds, cap);
+        if (r > 0)
+                return 1;
+
+        /* Caller has same UID as us, then let's grant access */
+        r = sd_bus_creds_get_uid(creds, &uid);
+        if (r >= 0) {
+                if (uid == getuid())
+                        return 1;
+        }
+
+        return sd_bus_error_setf(error, SD_BUS_ERROR_ACCESS_DENIED, "Access to %s.%s() not permitted.", c->interface, c->member);
+}
+
 static int method_callbacks_run(
                 sd_bus *bus,
                 sd_bus_message *m,
@@ -258,6 +331,7 @@ static int method_callbacks_run(
                 bool require_fallback,
                 bool *found_object) {
 
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
         const char *signature;
         void *u;
         int r;
@@ -270,9 +344,13 @@ static int method_callbacks_run(
         if (require_fallback && !c->parent->is_fallback)
                 return 0;
 
-        r = node_vtable_get_userdata(bus, m->path, c->parent, &u);
+        r = check_access(bus, m, c, &error);
+        if (r < 0)
+                return bus_maybe_reply_error(m, r, &error);
+
+        r = node_vtable_get_userdata(bus, m->path, c->parent, &u, &error);
         if (r <= 0)
-                return r;
+                return bus_maybe_reply_error(m, r, &error);
         if (bus->nodes_modified)
                 return 0;
 
@@ -291,23 +369,21 @@ static int method_callbacks_run(
         if (!signature)
                 return -EINVAL;
 
-        if (!streq(strempty(c->vtable->x.method.signature), signature)) {
-                r = sd_bus_reply_method_errorf(m,
-                                               SD_BUS_ERROR_INVALID_ARGS,
-                                               "Invalid arguments '%s' to call %s:%s, expecting '%s'.",
-                                               signature, c->interface, c->member, strempty(c->vtable->x.method.signature));
-                if (r < 0)
-                        return r;
+        if (!streq(strempty(c->vtable->x.method.signature), signature))
+                return sd_bus_reply_method_errorf(
+                                m,
+                                SD_BUS_ERROR_INVALID_ARGS,
+                                "Invalid arguments '%s' to call %s.%s(), expecting '%s'.",
+                                signature, c->interface, c->member, strempty(c->vtable->x.method.signature));
 
-                return 1;
-        }
+        /* Keep track what the signature of the reply to this message
+         * should be, so that this can be enforced when sealing the
+         * reply. */
+        m->enforced_reply_signature = strempty(c->vtable->x.method.result);
 
         if (c->vtable->x.method.handler) {
-                _cleanup_bus_error_free_ sd_bus_error error_buffer = SD_BUS_ERROR_NULL;
-
-                r = c->vtable->x.method.handler(bus, m, u, &error_buffer);
-
-                return bus_maybe_reply_error(m, r, &error_buffer);
+                r = c->vtable->x.method.handler(bus, m, u, &error);
+                return bus_maybe_reply_error(m, r, &error);
         }
 
         /* If the method callback is NULL, make this a successful NOP */
@@ -329,6 +405,7 @@ static int invoke_property_get(
                 sd_bus_error *error) {
 
         const void *p;
+        int r;
 
         assert(bus);
         assert(v);
@@ -337,8 +414,14 @@ static int invoke_property_get(
         assert(property);
         assert(reply);
 
-        if (v->x.property.get)
-                return v->x.property.get(bus, path, interface, property, reply, userdata, error);
+        if (v->x.property.get) {
+                r = v->x.property.get(bus, path, interface, property, reply, userdata, error);
+                if (r < 0)
+                        return r;
+                if (sd_bus_error_is_set(error))
+                        return -sd_bus_error_get_errno(error);
+                return r;
+        }
 
         /* Automatic handling if no callback is defined. */
 
@@ -387,8 +470,14 @@ static int invoke_property_set(
         assert(property);
         assert(value);
 
-        if (v->x.property.set)
-                return v->x.property.set(bus, path, interface, property, value, userdata, error);
+        if (v->x.property.set) {
+                r = v->x.property.set(bus, path, interface, property, value, userdata, error);
+                if (r < 0)
+                        return r;
+                if (sd_bus_error_is_set(error))
+                        return -sd_bus_error_get_errno(error);
+                return r;
+        }
 
         /*  Automatic handling if no callback is defined. */
 
@@ -449,9 +538,9 @@ static int property_get_set_callbacks_run(
         if (require_fallback && !c->parent->is_fallback)
                 return 0;
 
-        r = vtable_property_get_userdata(bus, m->path, c, &u);
+        r = vtable_property_get_userdata(bus, m->path, c, &u, &error);
         if (r <= 0)
-                return r;
+                return bus_maybe_reply_error(m, r, &error);
         if (bus->nodes_modified)
                 return 0;
 
@@ -473,11 +562,14 @@ static int property_get_set_callbacks_run(
                 if (r < 0)
                         return r;
 
+                /* Note that we do not do an access check here. Read
+                 * access to properties is always unrestricted, since
+                 * PropertiesChanged signals broadcast contents
+                 * anyway. */
+
                 r = invoke_property_get(bus, c->vtable, m->path, c->interface, c->member, reply, u, &error);
                 if (r < 0)
-                        return sd_bus_reply_method_errno(m, r, &error);
-                if (sd_bus_error_is_set(&error))
-                        return sd_bus_reply_method_error(m, &error);
+                        return bus_maybe_reply_error(m, r, &error);
 
                 if (bus->nodes_modified)
                         return 0;
@@ -502,11 +594,13 @@ static int property_get_set_callbacks_run(
                 if (r < 0)
                         return r;
 
+                r = check_access(bus, m, c, &error);
+                if (r < 0)
+                        return bus_maybe_reply_error(m, r, &error);
+
                 r = invoke_property_set(bus, c->vtable, m->path, c->interface, c->member, m, u, &error);
                 if (r < 0)
-                        return sd_bus_reply_method_errno(m, r, &error);
-                if (sd_bus_error_is_set(&error))
-                        return sd_bus_reply_method_error(m, &error);
+                        return bus_maybe_reply_error(m, r, &error);
 
                 if (bus->nodes_modified)
                         return 0;
@@ -539,10 +633,16 @@ static int vtable_append_all_properties(
         assert(path);
         assert(c);
 
+        if (c->vtable[0].flags & SD_BUS_VTABLE_HIDDEN)
+                return 1;
+
         for (v = c->vtable+1; v->type != _SD_BUS_VTABLE_END; v++) {
                 if (v->type != _SD_BUS_VTABLE_PROPERTY && v->type != _SD_BUS_VTABLE_WRITABLE_PROPERTY)
                         continue;
 
+                if (v->flags & SD_BUS_VTABLE_HIDDEN)
+                        continue;
+
                 r = sd_bus_message_open_container(reply, 'e', "sv");
                 if (r < 0)
                         return r;
@@ -556,12 +656,8 @@ static int vtable_append_all_properties(
                         return r;
 
                 r = invoke_property_get(bus, v, path, c->interface, v->x.property.member, reply, vtable_property_convert_userdata(v, userdata), error);
-                if (sd_bus_error_is_set(error))
-                        return 0;
-                if (r < 0) {
-                        sd_bus_error_set_errno(error, r);
-                        return 0;
-                }
+                if (r < 0)
+                        return r;
                 if (bus->nodes_modified)
                         return 0;
 
@@ -614,9 +710,9 @@ static int property_get_all_callbacks_run(
                 if (require_fallback && !c->is_fallback)
                         continue;
 
-                r = node_vtable_get_userdata(bus, m->path, c, &u);
+                r = node_vtable_get_userdata(bus, m->path, c, &u, &error);
                 if (r < 0)
-                        return r;
+                        return bus_maybe_reply_error(m, r, &error);
                 if (bus->nodes_modified)
                         return 0;
                 if (r == 0)
@@ -630,15 +726,7 @@ static int property_get_all_callbacks_run(
 
                 r = vtable_append_all_properties(bus, reply, m->path, c, u, &error);
                 if (r < 0)
-                        return r;
-
-                if (sd_bus_error_is_set(&error)) {
-                        r = sd_bus_reply_method_error(m, &error);
-                        if (r < 0)
-                                return r;
-
-                        return 1;
-                }
+                        return bus_maybe_reply_error(m, r, &error);
                 if (bus->nodes_modified)
                         return 0;
         }
@@ -702,11 +790,12 @@ static bool bus_node_exists(
         }
 
         LIST_FOREACH(vtables, c, n->vtables) {
+                _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
 
                 if (require_fallback && !c->is_fallback)
                         continue;
 
-                if (node_vtable_get_userdata(bus, path, c, NULL) > 0)
+                if (node_vtable_get_userdata(bus, path, c, NULL, &error) > 0)
                         return true;
                 if (bus->nodes_modified)
                         return false;
@@ -722,6 +811,7 @@ static int process_introspect(
                 bool require_fallback,
                 bool *found_object) {
 
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
         _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
         _cleanup_set_free_free_ Set *s = NULL;
         const char *previous_interface = NULL;
@@ -735,13 +825,13 @@ static int process_introspect(
         assert(n);
         assert(found_object);
 
-        r = get_child_nodes(bus, m->path, n, &s);
+        r = get_child_nodes(bus, m->path, n, &s, &error);
         if (r < 0)
-                return r;
+                return bus_maybe_reply_error(m, r, &error);
         if (bus->nodes_modified)
                 return 0;
 
-        r = introspect_begin(&intro);
+        r = introspect_begin(&intro, bus->trusted);
         if (r < 0)
                 return r;
 
@@ -755,16 +845,23 @@ static int process_introspect(
                 if (require_fallback && !c->is_fallback)
                         continue;
 
-                r = node_vtable_get_userdata(bus, m->path, c, NULL);
-                if (r < 0)
-                        return r;
-                if (bus->nodes_modified)
-                        return 0;
+                r = node_vtable_get_userdata(bus, m->path, c, NULL, &error);
+                if (r < 0) {
+                        r = bus_maybe_reply_error(m, r, &error);
+                        goto finish;
+                }
+                if (bus->nodes_modified) {
+                        r = 0;
+                        goto finish;
+                }
                 if (r == 0)
                         continue;
 
                 empty = false;
 
+                if (c->vtable[0].flags & SD_BUS_VTABLE_HIDDEN)
+                        continue;
+
                 if (!streq_ptr(previous_interface, c->interface)) {
 
                         if (previous_interface)
@@ -846,7 +943,7 @@ static int object_manager_serialize_path(
                 if (require_fallback && !i->is_fallback)
                         continue;
 
-                r = node_vtable_get_userdata(bus, path, i, &u);
+                r = node_vtable_get_userdata(bus, path, i, &u, error);
                 if (r < 0)
                         return r;
                 if (bus->nodes_modified)
@@ -905,8 +1002,6 @@ static int object_manager_serialize_path(
                 r = vtable_append_all_properties(bus, reply, path, i, u, error);
                 if (r < 0)
                         return r;
-                if (sd_bus_error_is_set(error))
-                        return 0;
                 if (bus->nodes_modified)
                         return 0;
 
@@ -954,8 +1049,6 @@ static int object_manager_serialize_path_and_fallbacks(
         r = object_manager_serialize_path(bus, reply, path, path, false, error);
         if (r < 0)
                 return r;
-        if (sd_bus_error_is_set(error))
-                return 0;
         if (bus->nodes_modified)
                 return 0;
 
@@ -965,8 +1058,6 @@ static int object_manager_serialize_path_and_fallbacks(
                 r = object_manager_serialize_path(bus, reply, prefix, path, true, error);
                 if (r < 0)
                         return r;
-                if (sd_bus_error_is_set(error))
-                        return 0;
                 if (bus->nodes_modified)
                         return 0;
         }
@@ -981,6 +1072,7 @@ static int process_get_managed_objects(
                 bool require_fallback,
                 bool *found_object) {
 
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
         _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
         _cleanup_set_free_free_ Set *s = NULL;
         bool empty;
@@ -994,7 +1086,7 @@ static int process_get_managed_objects(
         if (!bus_node_with_object_manager(bus, n))
                 return 0;
 
-        r = get_child_nodes(bus, m->path, n, &s);
+        r = get_child_nodes(bus, m->path, n, &s, &error);
         if (r < 0)
                 return r;
         if (bus->nodes_modified)
@@ -1037,19 +1129,9 @@ static int process_get_managed_objects(
                 char *path;
 
                 SET_FOREACH(path, s, i) {
-                        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
-
                         r = object_manager_serialize_path_and_fallbacks(bus, reply, path, &error);
                         if (r < 0)
-                                return -ENOMEM;
-
-                        if (sd_bus_error_is_set(&error)) {
-                                r = sd_bus_reply_method_error(m, &error);
-                                if (r < 0)
-                                        return r;
-
-                                return 1;
-                        }
+                                return r;
 
                         if (bus->nodes_modified)
                                 return 0;
@@ -1127,7 +1209,7 @@ static int object_find_and_run(
 
                         r = sd_bus_message_read(m, "ss", &vtable_key.interface, &vtable_key.member);
                         if (r < 0)
-                                return r;
+                                return sd_bus_reply_method_errorf(m, SD_BUS_ERROR_INVALID_ARGS, "Expected interface and member parameters");
 
                         v = hashmap_get(bus->vtable_properties, &vtable_key);
                         if (v) {
@@ -1145,7 +1227,7 @@ static int object_find_and_run(
 
                         r = sd_bus_message_read(m, "s", &iface);
                         if (r < 0)
-                                return r;
+                                return sd_bus_reply_method_errorf(m, SD_BUS_ERROR_INVALID_ARGS, "Expected interface parameter");
 
                         if (iface[0] == 0)
                                 iface = NULL;
@@ -1157,12 +1239,18 @@ static int object_find_and_run(
 
         } else if (sd_bus_message_is_method_call(m, "org.freedesktop.DBus.Introspectable", "Introspect")) {
 
+                if (!isempty(sd_bus_message_get_signature(m, true)))
+                        return sd_bus_reply_method_errorf(m, SD_BUS_ERROR_INVALID_ARGS, "Expected no parameters");
+
                 r = process_introspect(bus, m, n, require_fallback, found_object);
                 if (r != 0)
                         return r;
 
         } else if (sd_bus_message_is_method_call(m, "org.freedesktop.DBus.ObjectManager", "GetManagedObjects")) {
 
+                if (!isempty(sd_bus_message_get_signature(m, true)))
+                        return sd_bus_reply_method_errorf(m, SD_BUS_ERROR_INVALID_ARGS, "Expected no parameters");
+
                 r = process_get_managed_objects(bus, m, n, require_fallback, found_object);
                 if (r != 0)
                         return r;
@@ -1193,12 +1281,16 @@ int bus_process_object(sd_bus *bus, sd_bus_message *m) {
         if (m->header->type != SD_BUS_MESSAGE_METHOD_CALL)
                 return 0;
 
-        if (!m->path)
+        if (hashmap_isempty(bus->nodes))
                 return 0;
 
-        if (hashmap_isempty(bus->nodes))
+        /* Never respond to broadcast messages */
+        if (bus->bus_client && !m->destination)
                 return 0;
 
+        assert(m->path);
+        assert(m->member);
+
         pl = strlen(m->path);
         do {
                 char prefix[pl+1];
@@ -1246,7 +1338,8 @@ int bus_process_object(sd_bus *bus, sd_bus_message *m) {
 static struct node *bus_node_allocate(sd_bus *bus, const char *path) {
         struct node *n, *parent;
         const char *e;
-        char *s, *p;
+        _cleanup_free_ char *s = NULL;
+        char *p;
         int r;
 
         assert(bus);
@@ -1274,10 +1367,8 @@ static struct node *bus_node_allocate(sd_bus *bus, const char *path) {
                 p = strndupa(path, MAX(1, path - e));
 
                 parent = bus_node_allocate(bus, p);
-                if (!parent) {
-                        free(s);
+                if (!parent)
                         return NULL;
-                }
         }
 
         n = new0(struct node, 1);
@@ -1286,10 +1377,11 @@ static struct node *bus_node_allocate(sd_bus *bus, const char *path) {
 
         n->parent = parent;
         n->path = s;
+        s = NULL; /* do not free */
 
-        r = hashmap_put(bus->nodes, s, n);
+        r = hashmap_put(bus->nodes, n->path, n);
         if (r < 0) {
-                free(s);
+                free(n->path);
                 free(n);
                 return NULL;
         }
@@ -1588,7 +1680,7 @@ static int add_object_vtable_internal(
                             !signature_is_valid(strempty(v->x.method.signature), false) ||
                             !signature_is_valid(strempty(v->x.method.result), false) ||
                             !(v->x.method.handler || (isempty(v->x.method.signature) && isempty(v->x.method.result))) ||
-                            v->flags & (SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE|SD_BUS_VTABLE_PROPERTY_INVALIDATE_ONLY)) {
+                            v->flags & (SD_BUS_VTABLE_PROPERTY_CONST|SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE|SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION)) {
                                 r = -EINVAL;
                                 goto fail;
                         }
@@ -1630,12 +1722,12 @@ static int add_object_vtable_internal(
                             !signature_is_single(v->x.property.signature, false) ||
                             !(v->x.property.get || bus_type_is_basic(v->x.property.signature[0]) || streq(v->x.property.signature, "as")) ||
                             v->flags & SD_BUS_VTABLE_METHOD_NO_REPLY ||
-                            (v->flags & SD_BUS_VTABLE_PROPERTY_INVALIDATE_ONLY && !(v->flags & SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE))) {
+                            (!!(v->flags & SD_BUS_VTABLE_PROPERTY_CONST) + !!(v->flags & SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE) + !!(v->flags & SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION)) > 1 ||
+                            (v->flags & SD_BUS_VTABLE_UNPRIVILEGED && v->type == _SD_BUS_VTABLE_PROPERTY)) {
                                 r = -EINVAL;
                                 goto fail;
                         }
 
-
                         m = new0(struct vtable_member, 1);
                         if (!m) {
                                 r = -ENOMEM;
@@ -1660,7 +1752,8 @@ static int add_object_vtable_internal(
                 case _SD_BUS_VTABLE_SIGNAL:
 
                         if (!member_name_is_valid(v->x.signal.member) ||
-                            !signature_is_valid(strempty(v->x.signal.signature), false)) {
+                            !signature_is_valid(strempty(v->x.signal.signature), false) ||
+                            v->flags & SD_BUS_VTABLE_UNPRIVILEGED) {
                                 r = -EINVAL;
                                 goto fail;
                         }
@@ -1854,6 +1947,7 @@ static int emit_properties_changed_on_interface(
                 bool require_fallback,
                 char **names) {
 
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
         _cleanup_bus_message_unref_ sd_bus_message *m = NULL;
         bool has_invalidating = false, has_changing = false;
         struct vtable_member key = {};
@@ -1894,7 +1988,7 @@ static int emit_properties_changed_on_interface(
                 if (!streq(c->interface, interface))
                         continue;
 
-                r = node_vtable_get_userdata(bus, path, c, &u);
+                r = node_vtable_get_userdata(bus, path, c, &u, &error);
                 if (r < 0)
                         return r;
                 if (bus->nodes_modified)
@@ -1903,7 +1997,6 @@ static int emit_properties_changed_on_interface(
                         continue;
 
                 STRV_FOREACH(property, names) {
-                        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
                         struct vtable_member *v;
 
                         assert_return(member_name_is_valid(*property), -EINVAL);
@@ -1919,9 +2012,10 @@ static int emit_properties_changed_on_interface(
                         if (c != v->parent)
                                 continue;
 
-                        assert_return(v->vtable->flags & SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE, -EDOM);
+                        assert_return(v->vtable->flags & SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE ||
+                                      v->vtable->flags & SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION, -EDOM);
 
-                        if (v->vtable->flags & SD_BUS_VTABLE_PROPERTY_INVALIDATE_ONLY) {
+                        if (v->vtable->flags & SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION) {
                                 has_invalidating = true;
                                 continue;
                         }
@@ -1943,8 +2037,6 @@ static int emit_properties_changed_on_interface(
                         r = invoke_property_get(bus, v->vtable, m->path, interface, *property, m, vtable_property_convert_userdata(v->vtable, u), &error);
                         if (r < 0)
                                 return r;
-                        if (sd_bus_error_is_set(&error))
-                                return sd_bus_error_get_errno(&error);
                         if (bus->nodes_modified)
                                 return 0;
 
@@ -1977,7 +2069,7 @@ static int emit_properties_changed_on_interface(
                         if (!streq(c->interface, interface))
                                 continue;
 
-                        r = node_vtable_get_userdata(bus, path, c, &u);
+                        r = node_vtable_get_userdata(bus, path, c, &u, &error);
                         if (r < 0)
                                 return r;
                         if (bus->nodes_modified)
@@ -1992,7 +2084,7 @@ static int emit_properties_changed_on_interface(
                                 assert_se(v = hashmap_get(bus->vtable_properties, &key));
                                 assert(c == v->parent);
 
-                                if (!(v->vtable->flags & SD_BUS_VTABLE_PROPERTY_INVALIDATE_ONLY))
+                                if (!(v->vtable->flags & SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION))
                                         continue;
 
                                 r = sd_bus_message_append(m, "s", *property);
@@ -2109,7 +2201,7 @@ static int interfaces_added_append_one_prefix(
                 if (!streq(c->interface, interface))
                         continue;
 
-                r = node_vtable_get_userdata(bus, path, c, &u);
+                r = node_vtable_get_userdata(bus, path, c, &u, &error);
                 if (r < 0)
                         return r;
                 if (bus->nodes_modified)