sd-bus: sync with kdbus upstream (ABI break)

kdbus has seen a larger update than expected lately, most notably with
kdbusfs, a file system to expose the kdbus control files:

 * Each time a file system of this type is mounted, a new kdbus
   domain is created.

 * The layout inside each mount point is the same as before, except
   that domains are not hierarchically nested anymore.

 * Domains are therefore also unnamed now.

 * Unmounting a kdbusfs will automatically also detroy the
   associated domain.

 * Hence, the action of creating a kdbus domain is now as
   privileged as mounting a filesystem.

 * This way, we can get around creating dev nodes for everything,
   which is last but not least something that is not limited by
   20-bit minor numbers.

The kdbus specific bits in nspawn have all been dropped now, as nspawn
can rely on the container OS to set up its own kdbus domain, simply by
mounting a new instance.

A new set of mounts has been added to mount things *after* the kernel
modules have been loaded. For now, only kdbus is in this set, which is
invoked with mount_setup_late().

17 files changed, 64 insertions, 165 deletions

diff --git a/src/core/kmod-setup.c b/src/core/kmod-setup.c
index 38e1726e08..8136d3c0f8 100644
--- a/src/core/kmod-setup.c
+++ b/src/core/kmod-setup.c
@@ -71,7 +71,7 @@ int kmod_setup(void) {
                 { "unix",    "/proc/net/unix",         true, NULL },
 
                 /* IPC is needed before we bring up any other services */
-                { "kdbus",   "/sys/bus/kdbus",         false, cmdline_check_kdbus },
+                { "kdbus",   "/sys/fs/kdbus",          false, cmdline_check_kdbus },
         };
         struct kmod_ctx *ctx = NULL;
         unsigned int i;
diff --git a/src/core/main.c b/src/core/main.c
index 56a1f6193c..d563ae3509 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -1556,6 +1556,7 @@ int main(int argc, char *argv[]) {
 #ifdef HAVE_KMOD
                 kmod_setup();
 #endif
+                mount_setup_late();
                 hostname_setup();
                 machine_id_setup(NULL);
                 loopback_setup();
diff --git a/src/core/manager.c b/src/core/manager.c
index 1bc36a6c41..2bc1058436 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -729,13 +729,6 @@ static int manager_setup_kdbus(Manager *m) {
         }
 
         log_debug("Successfully set up kdbus on %s", p);
-
-        /* Create the namespace directory here, so that the contents
-         * of that directory is not visible to non-root users. This is
-         * necessary to ensure that users cannot get access to busses
-         * of virtualized users when no UID namespacing is used. */
-        if (m->running_as == SYSTEMD_SYSTEM)
-                mkdir_p_label("/dev/kdbus/domain", 0700);
 #endif
 
         return 0;
diff --git a/src/core/mount-setup.c b/src/core/mount-setup.c
index cda25ede13..e9a2ec6886 100644
--- a/src/core/mount-setup.c
+++ b/src/core/mount-setup.c
@@ -110,6 +110,13 @@ static const MountPoint mount_table[] = {
 #endif
 };
 
+static const MountPoint mount_table_late[] = {
+#ifdef ENABLE_KDBUS
+        { "kdbusfs",    "/sys/fs/kdbus",             "kdbusfs",    NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
+          NULL,       MNT_IN_CONTAINER },
+#endif
+};
+
 /* These are API file systems that might be mounted by other software,
  * we just list them here so that we know that we should ignore them */
 
@@ -221,6 +228,21 @@ int mount_setup_early(void) {
         return r;
 }
 
+int mount_setup_late(void) {
+        unsigned i;
+        int r = 0;
+
+        for (i = 0; i < ELEMENTSOF(mount_table_late); i ++)  {
+                int j;
+
+                j = mount_one(mount_table_late + i, false);
+                if (r == 0)
+                        r = j;
+        }
+
+        return r;
+}
+
 int mount_cgroup_controllers(char ***join_controllers) {
         _cleanup_set_free_free_ Set *controllers = NULL;
         _cleanup_fclose_ FILE *f;
diff --git a/src/core/mount-setup.h b/src/core/mount-setup.h
index 4b521ad0e1..928bd6edfe 100644
--- a/src/core/mount-setup.h
+++ b/src/core/mount-setup.h
@@ -24,6 +24,7 @@
 #include <stdbool.h>
 
 int mount_setup_early(void);
+int mount_setup_late(void);
 
 int mount_setup(bool loaded_policy);
 
diff --git a/src/core/namespace.c b/src/core/namespace.c
index 4bc288de1d..eb7f2ad60d 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -145,7 +145,7 @@ static int mount_dev(BindMount *m) {
                 "/dev/tty\0";
 
         char temporary_mount[] = "/tmp/namespace-dev-XXXXXX";
-        const char *d, *dev = NULL, *devpts = NULL, *devshm = NULL, *devkdbus = NULL, *devhugepages = NULL, *devmqueue = NULL, *devlog = NULL, *devptmx = NULL;
+        const char *d, *dev = NULL, *devpts = NULL, *devshm = NULL, *devhugepages = NULL, *devmqueue = NULL, *devlog = NULL, *devptmx = NULL;
         _cleanup_umask_ mode_t u;
         int r;
 
@@ -185,10 +185,6 @@ static int mount_dev(BindMount *m) {
         mkdir(devmqueue, 0755);
         mount("/dev/mqueue", devmqueue, NULL, MS_BIND, NULL);
 
-        devkdbus = strappenda(temporary_mount, "/dev/kdbus");
-        mkdir(devkdbus, 0755);
-        mount("/dev/kdbus", devkdbus, NULL, MS_BIND, NULL);
-
         devhugepages = strappenda(temporary_mount, "/dev/hugepages");
         mkdir(devhugepages, 0755);
         mount("/dev/hugepages", devhugepages, NULL, MS_BIND, NULL);
@@ -254,9 +250,6 @@ fail:
         if (devshm)
                 umount(devshm);
 
-        if (devkdbus)
-                umount(devkdbus);
-
         if (devhugepages)
                 umount(devhugepages);
 
diff --git a/src/dbus1-generator/dbus1-generator.c b/src/dbus1-generator/dbus1-generator.c
index 3c4522b589..57af80c0e9 100644
--- a/src/dbus1-generator/dbus1-generator.c
+++ b/src/dbus1-generator/dbus1-generator.c
@@ -319,7 +319,7 @@ int main(int argc, char *argv[]) {
 
         umask(0022);
 
-        if (access("/dev/kdbus/control", F_OK) < 0)
+        if (access("/sys/fs/kdbus/control", F_OK) < 0)
                 return 0;
 
         r = cg_pid_get_owner_uid(0, NULL);
diff --git a/src/libsystemd/sd-bus/PORTING-DBUS1 b/src/libsystemd/sd-bus/PORTING-DBUS1
index 81e94132b3..2dedb28bcf 100644
--- a/src/libsystemd/sd-bus/PORTING-DBUS1
+++ b/src/libsystemd/sd-bus/PORTING-DBUS1
@@ -14,11 +14,11 @@ GVariant compatible marshaler to your library first.
 
 After you have done that: here's the basic principle how kdbus works:
 
-You connect to a bus by opening its bus node in /dev/kdbus/. All
+You connect to a bus by opening its bus node in /sys/fs/kdbus/. All
 buses have a device node there, it starts with a numeric UID of the
 owner of the bus, followed by a dash and a string identifying the
-bus. The system bus is thus called /dev/kdbus/0-system, and for user
-buses the device node is /dev/kdbus/1000-user (if 1000 is your user
+bus. The system bus is thus called /sys/fs/kdbus/0-system, and for user
+buses the device node is /sys/fs/kdbus/1000-user (if 1000 is your user
 id).
 
 (Before we proceed, please always keep a copy of libsystemd next
@@ -496,12 +496,12 @@ parameter.
 Client libraries should use the following connection string when
 connecting to the system bus:
 
-   kernel:path=/dev/kdbus/0-system/bus;unix:path=/var/run/dbus/system_bus_socket
+   kernel:path=/sys/fs/kdbus/0-system/bus;unix:path=/var/run/dbus/system_bus_socket
 
 This will ensure that kdbus is preferred over the legacy AF_UNIX
 socket, but compatibility is kept. For the user bus use:
 
-   kernel:path=/dev/kdbus/$UID-user/bus;unix:path=$XDG_RUNTIME_DIR/bus
+   kernel:path=/sys/fs/kdbus/$UID-user/bus;unix:path=$XDG_RUNTIME_DIR/bus
 
 With $UID replaced by the callers numer user ID, and $XDG_RUNTIME_DIR
 following the XDG basedir spec.
diff --git a/src/libsystemd/sd-bus/bus-kernel.c b/src/libsystemd/sd-bus/bus-kernel.c
index 5e7bc12239..afac3b6bcc 100644
--- a/src/libsystemd/sd-bus/bus-kernel.c
+++ b/src/libsystemd/sd-bus/bus-kernel.c
@@ -1282,7 +1282,7 @@ int bus_kernel_create_bus(const char *name, bool world, char **s) {
         assert(name);
         assert(s);
 
-        fd = open("/dev/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC);
+        fd = open("/sys/fs/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC);
         if (fd < 0)
                 return -errno;
 
@@ -1323,7 +1323,7 @@ int bus_kernel_create_bus(const char *name, bool world, char **s) {
         if (s) {
                 char *p;
 
-                p = strjoin("/dev/kdbus/", n->str, "/bus", NULL);
+                p = strjoin("/sys/fs/kdbus/", n->str, "/bus", NULL);
                 if (!p) {
                         safe_close(fd);
                         return -ENOMEM;
@@ -1403,7 +1403,7 @@ int bus_kernel_open_bus_fd(const char *bus, char **path) {
         int fd;
         size_t len;
 
-        len = strlen("/dev/kdbus/") + DECIMAL_STR_MAX(uid_t) + 1 + strlen(bus) + strlen("/bus") + 1;
+        len = strlen("/sys/fs/kdbus/") + DECIMAL_STR_MAX(uid_t) + 1 + strlen(bus) + strlen("/bus") + 1;
 
         if (path) {
                 p = malloc(len);
@@ -1412,7 +1412,7 @@ int bus_kernel_open_bus_fd(const char *bus, char **path) {
                 *path = p;
         } else
                 p = alloca(len);
-        sprintf(p, "/dev/kdbus/" UID_FMT "-%s/bus", getuid(), bus);
+        sprintf(p, "/sys/fs/kdbus/" UID_FMT "-%s/bus", getuid(), bus);
 
         fd = open(p, O_RDWR|O_NOCTTY|O_CLOEXEC);
         if (fd < 0)
@@ -1585,58 +1585,6 @@ int bus_kernel_make_starter(
         return fd;
 }
 
-int bus_kernel_create_domain(const char *name, char **s) {
-        struct kdbus_cmd_make *make;
-        struct kdbus_item *n;
-        int fd;
-
-        assert(name);
-        assert(s);
-
-        fd = open("/dev/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC);
-        if (fd < 0)
-                return -errno;
-
-        make = alloca0_align(ALIGN8(offsetof(struct kdbus_cmd_make, items) +
-                                    offsetof(struct kdbus_item, str) +
-                                    strlen(name) + 1),
-                             8);
-
-        n = make->items;
-        strcpy(n->str, name);
-        n->size = offsetof(struct kdbus_item, str) + strlen(n->str) + 1;
-        n->type = KDBUS_ITEM_MAKE_NAME;
-
-        make->size = ALIGN8(offsetof(struct kdbus_cmd_make, items) + n->size);
-        make->flags = KDBUS_MAKE_ACCESS_WORLD;
-
-        if (ioctl(fd, KDBUS_CMD_DOMAIN_MAKE, make) < 0) {
-                safe_close(fd);
-                return -errno;
-        }
-
-        /* The higher 32bit of the flags field are considered
-         * 'incompatible flags'. Refuse them all for now. */
-        if (make->flags > 0xFFFFFFFFULL) {
-                safe_close(fd);
-                return -ENOTSUP;
-        }
-
-        if (s) {
-                char *p;
-
-                p = strappend("/dev/kdbus/domain/", name);
-                if (!p) {
-                        safe_close(fd);
-                        return -ENOMEM;
-                }
-
-                *s = p;
-        }
-
-        return fd;
-}
-
 int bus_kernel_try_close(sd_bus *bus) {
         assert(bus);
         assert(bus->is_kernel);
diff --git a/src/libsystemd/sd-bus/bus-kernel.h b/src/libsystemd/sd-bus/bus-kernel.h
index f1d832a764..c1ee285cd1 100644
--- a/src/libsystemd/sd-bus/bus-kernel.h
+++ b/src/libsystemd/sd-bus/bus-kernel.h
@@ -71,7 +71,6 @@ int bus_kernel_make_starter(int fd, const char *name, bool activating, bool acce
 
 int bus_kernel_create_bus(const char *name, bool world, char **s);
 int bus_kernel_create_endpoint(const char *bus_name, const char *ep_name, char **path);
-int bus_kernel_create_domain(const char *name, char **s);
 
 int bus_kernel_set_endpoint_policy(int fd, uid_t uid, BusEndpoint *ep);
 
diff --git a/src/libsystemd/sd-bus/kdbus.h b/src/libsystemd/sd-bus/kdbus.h
index a870b176cf..e3a80c352d 100644
--- a/src/libsystemd/sd-bus/kdbus.h
+++ b/src/libsystemd/sd-bus/kdbus.h
@@ -635,8 +635,8 @@ enum kdbus_make_flags {
  * @kernel_flags:	Supported flags for the used command, kernel → userspace
  * @items:		Items describing details
  *
- * This structure is used with the KDBUS_CMD_BUS_MAKE, KDBUS_CMD_ENDPOINT_MAKE
- * and KDBUS_CMD_DOMAIN_MAKE ioctls.
+ * This structure is used with the KDBUS_CMD_BUS_MAKE and
+ * KDBUS_CMD_ENDPOINT_MAKE ioctls.
  */
 struct kdbus_cmd_make {
 	__u64 size;
@@ -839,8 +839,6 @@ struct kdbus_cmd_match {
  *				name. The bus is immediately shut down and
  *				cleaned up when the opened "control" device node
  *				is closed.
- * KDBUS_CMD_DOMAIN_MAKE:	Similar to KDBUS_CMD_BUS_MAKE, but it creates a
- *				new kdbus domain.
  * KDBUS_CMD_ENDPOINT_MAKE:	Creates a new named special endpoint to talk to
  *				the bus. Such endpoints usually carry a more
  *				restrictive policy and grant restricted access
@@ -887,44 +885,42 @@ struct kdbus_cmd_match {
  */
 #define KDBUS_CMD_BUS_MAKE		_IOW(KDBUS_IOCTL_MAGIC, 0x00,	\
 					     struct kdbus_cmd_make)
-#define KDBUS_CMD_DOMAIN_MAKE		_IOW(KDBUS_IOCTL_MAGIC, 0x10,	\
-					     struct kdbus_cmd_make)
-#define KDBUS_CMD_ENDPOINT_MAKE		_IOW(KDBUS_IOCTL_MAGIC, 0x20,	\
+#define KDBUS_CMD_ENDPOINT_MAKE		_IOW(KDBUS_IOCTL_MAGIC, 0x10,	\
 					     struct kdbus_cmd_make)
 
-#define KDBUS_CMD_HELLO			_IOWR(KDBUS_IOCTL_MAGIC, 0x30,	\
+#define KDBUS_CMD_HELLO			_IOWR(KDBUS_IOCTL_MAGIC, 0x20,	\
 					      struct kdbus_cmd_hello)
-#define KDBUS_CMD_BYEBYE		_IO(KDBUS_IOCTL_MAGIC, 0x31)	\
+#define KDBUS_CMD_BYEBYE		_IO(KDBUS_IOCTL_MAGIC, 0x21)	\
 
-#define KDBUS_CMD_MSG_SEND		_IOWR(KDBUS_IOCTL_MAGIC, 0x40,	\
+#define KDBUS_CMD_MSG_SEND		_IOWR(KDBUS_IOCTL_MAGIC, 0x30,	\
 					      struct kdbus_msg)
-#define KDBUS_CMD_MSG_RECV		_IOWR(KDBUS_IOCTL_MAGIC, 0x41,	\
+#define KDBUS_CMD_MSG_RECV		_IOWR(KDBUS_IOCTL_MAGIC, 0x31,	\
 					      struct kdbus_cmd_recv)
-#define KDBUS_CMD_MSG_CANCEL		_IOW(KDBUS_IOCTL_MAGIC, 0x42,	\
+#define KDBUS_CMD_MSG_CANCEL		_IOW(KDBUS_IOCTL_MAGIC, 0x32,	\
 					     struct kdbus_cmd_cancel)
-#define KDBUS_CMD_FREE			_IOW(KDBUS_IOCTL_MAGIC, 0x43,	\
+#define KDBUS_CMD_FREE			_IOW(KDBUS_IOCTL_MAGIC, 0x33,	\
 					     struct kdbus_cmd_free)
 
-#define KDBUS_CMD_NAME_ACQUIRE		_IOWR(KDBUS_IOCTL_MAGIC, 0x50,	\
+#define KDBUS_CMD_NAME_ACQUIRE		_IOWR(KDBUS_IOCTL_MAGIC, 0x40,	\
 					      struct kdbus_cmd_name)
-#define KDBUS_CMD_NAME_RELEASE		_IOW(KDBUS_IOCTL_MAGIC, 0x51,	\
+#define KDBUS_CMD_NAME_RELEASE		_IOW(KDBUS_IOCTL_MAGIC, 0x41,	\
 					     struct kdbus_cmd_name)
-#define KDBUS_CMD_NAME_LIST		_IOWR(KDBUS_IOCTL_MAGIC, 0x52,	\
+#define KDBUS_CMD_NAME_LIST		_IOWR(KDBUS_IOCTL_MAGIC, 0x42,	\
 					      struct kdbus_cmd_name_list)
 
-#define KDBUS_CMD_CONN_INFO		_IOWR(KDBUS_IOCTL_MAGIC, 0x60,	\
+#define KDBUS_CMD_CONN_INFO		_IOWR(KDBUS_IOCTL_MAGIC, 0x50,	\
 					      struct kdbus_cmd_info)
-#define KDBUS_CMD_CONN_UPDATE		_IOW(KDBUS_IOCTL_MAGIC, 0x61,	\
+#define KDBUS_CMD_CONN_UPDATE		_IOW(KDBUS_IOCTL_MAGIC, 0x51,	\
 					     struct kdbus_cmd_update)
-#define KDBUS_CMD_BUS_CREATOR_INFO	_IOWR(KDBUS_IOCTL_MAGIC, 0x62,	\
+#define KDBUS_CMD_BUS_CREATOR_INFO	_IOWR(KDBUS_IOCTL_MAGIC, 0x52,	\
 					      struct kdbus_cmd_info)
 
-#define KDBUS_CMD_ENDPOINT_UPDATE	_IOW(KDBUS_IOCTL_MAGIC, 0x71,	\
+#define KDBUS_CMD_ENDPOINT_UPDATE	_IOW(KDBUS_IOCTL_MAGIC, 0x61,	\
 					     struct kdbus_cmd_update)
 
-#define KDBUS_CMD_MATCH_ADD		_IOW(KDBUS_IOCTL_MAGIC, 0x80,	\
+#define KDBUS_CMD_MATCH_ADD		_IOW(KDBUS_IOCTL_MAGIC, 0x70,	\
 					     struct kdbus_cmd_match)
-#define KDBUS_CMD_MATCH_REMOVE		_IOW(KDBUS_IOCTL_MAGIC, 0x81,	\
+#define KDBUS_CMD_MATCH_REMOVE		_IOW(KDBUS_IOCTL_MAGIC, 0x71,	\
 					     struct kdbus_cmd_match)
 
 #endif /* _KDBUS_UAPI_H_ */
diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c
index e6b47f7fd8..b1a1f79d86 100644
--- a/src/libsystemd/sd-bus/sd-bus.c
+++ b/src/libsystemd/sd-bus/sd-bus.c
@@ -807,7 +807,7 @@ static int parse_container_kernel_address(sd_bus *b, const char **p, char **guid
         machine = NULL;
 
         free(b->kernel);
-        b->kernel = strdup("/dev/kdbus/0-system/bus");
+        b->kernel = strdup("/sys/fs/kdbus/0-system/bus");
         if (!b->kernel)
                 return -ENOMEM;
 
diff --git a/src/login/pam_systemd.c b/src/login/pam_systemd.c
index 0c71177deb..9250a6903a 100644
--- a/src/login/pam_systemd.c
+++ b/src/login/pam_systemd.c
@@ -180,7 +180,7 @@ static int export_legacy_dbus_address(
         int r;
 
         /* skip export if kdbus is not active */
-        if (access("/dev/kdbus", F_OK) < 0)
+        if (access("/sys/fs/kdbus", F_OK) < 0)
                 return PAM_SUCCESS;
 
         if (asprintf(&s, KERNEL_USER_BUS_FMT ";" UNIX_USER_BUS_FMT,
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index fca3222a87..c2311b36d5 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -1441,26 +1441,6 @@ static int setup_journal(const char *directory) {
         return 0;
 }
 
-static int setup_kdbus(const char *dest, const char *path) {
-        const char *p;
-
-        if (!path)
-                return 0;
-
-        p = strappenda(dest, "/dev/kdbus");
-        if (mkdir(p, 0755) < 0) {
-                log_error("Failed to create kdbus path: %m");
-                return  -errno;
-        }
-
-        if (mount(path, p, "bind", MS_BIND, NULL) < 0) {
-                log_error("Failed to mount kdbus domain path: %m");
-                return -errno;
-        }
-
-        return 0;
-}
-
 static int drop_capabilities(void) {
         return capability_bounding_set_drop(~arg_retain, false);
 }
@@ -1546,7 +1526,7 @@ static int register_machine(pid_t pid, int local_ifindex) {
                         return r;
                 }
 
-                r = sd_bus_message_append(m, "(sv)", "DeviceAllow", "a(ss)", 11,
+                r = sd_bus_message_append(m, "(sv)", "DeviceAllow", "a(ss)", 9,
                                           /* Allow the container to
                                            * access and create the API
                                            * device nodes, so that
@@ -1566,18 +1546,7 @@ static int register_machine(pid_t pid, int local_ifindex) {
                                            * container to ever create
                                            * these device nodes. */
                                           "/dev/pts/ptmx", "rw",
-                                          "char-pts", "rw",
-                                          /* Allow the container
-                                           * access to all kdbus
-                                           * devices. Again, the
-                                           * container cannot create
-                                           * these nodes, only use
-                                           * them. We use a pretty
-                                           * open match here, so that
-                                           * the kernel API can still
-                                           * change. */
-                                          "char-kdbus", "rw",
-                                          "char-kdbus/*", "rw");
+                                          "char-pts", "rw");
                 if (r < 0) {
                         log_error("Failed to add device whitelist: %s", strerror(-r));
                         return r;
@@ -2991,9 +2960,9 @@ static int on_orderly_shutdown(sd_event_source *s, const struct signalfd_siginfo
 
 int main(int argc, char *argv[]) {
 
-        _cleanup_free_ char *kdbus_domain = NULL, *device_path = NULL, *root_device = NULL, *home_device = NULL, *srv_device = NULL;
+        _cleanup_free_ char *device_path = NULL, *root_device = NULL, *home_device = NULL, *srv_device = NULL;
         bool root_device_rw = true, home_device_rw = true, srv_device_rw = true;
-        _cleanup_close_ int master = -1, kdbus_fd = -1, image_fd = -1;
+        _cleanup_close_ int master = -1, image_fd = -1;
         _cleanup_close_pair_ int kmsg_socket_pair[2] = { -1, -1 };
         _cleanup_fdset_free_ FDSet *fds = NULL;
         int r = EXIT_FAILURE, k, n_fd_passed, loop_nr = -1;
@@ -3140,26 +3109,6 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
-        if (access("/dev/kdbus/control", F_OK) >= 0) {
-
-                if (arg_share_system) {
-                        kdbus_domain = strdup("/dev/kdbus");
-                        if (!kdbus_domain) {
-                                log_oom();
-                                goto finish;
-                        }
-                } else {
-                        const char *ns;
-
-                        ns = strappenda("machine-", arg_machine);
-                        kdbus_fd = bus_kernel_create_domain(ns, &kdbus_domain);
-                        if (r < 0)
-                                log_debug("Failed to create kdbus domain: %s", strerror(-r));
-                        else
-                                log_debug("Successfully created kdbus domain as %s", kdbus_domain);
-                }
-        }
-
         if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, kmsg_socket_pair) < 0) {
                 log_error("Failed to create kmsg socket pair: %m");
                 goto finish;
@@ -3365,9 +3314,6 @@ int main(int argc, char *argv[]) {
                         if (mount_tmpfs(arg_directory) < 0)
                                 _exit(EXIT_FAILURE);
 
-                        if (setup_kdbus(arg_directory, kdbus_domain) < 0)
-                                _exit(EXIT_FAILURE);
-
                         /* Tell the parent that we are ready, and that
                          * it can cgroupify us to that we lack access
                          * to certain devices and resources. */
diff --git a/src/shared/def.h b/src/shared/def.h
index 92394e8183..98e3e10fb6 100644
--- a/src/shared/def.h
+++ b/src/shared/def.h
@@ -62,7 +62,7 @@
 #endif
 
 #define UNIX_SYSTEM_BUS_PATH "unix:path=/var/run/dbus/system_bus_socket"
-#define KERNEL_SYSTEM_BUS_PATH "kernel:path=/dev/kdbus/0-system/bus"
+#define KERNEL_SYSTEM_BUS_PATH "kernel:path=/sys/fs/kdbus/0-system/bus"
 
 #ifdef ENABLE_KDBUS
 #  define DEFAULT_SYSTEM_BUS_PATH KERNEL_SYSTEM_BUS_PATH ";" UNIX_SYSTEM_BUS_PATH
@@ -71,7 +71,7 @@
 #endif
 
 #define UNIX_USER_BUS_FMT "unix:path=%s/bus"
-#define KERNEL_USER_BUS_FMT "kernel:path=/dev/kdbus/"UID_FMT"-user/bus"
+#define KERNEL_USER_BUS_FMT "kernel:path=/sys/fs/kdbus/"UID_FMT"-user/bus"
 
 #define PLYMOUTH_SOCKET {                                       \
                 .un.sun_family = AF_UNIX,                       \
diff --git a/units/systemd-bus-proxyd@.service.in b/units/systemd-bus-proxyd@.service.in
index eef703f2f7..fdcd3029fd 100644
--- a/units/systemd-bus-proxyd@.service.in
+++ b/units/systemd-bus-proxyd@.service.in
@@ -12,7 +12,7 @@ Description=Legacy D-Bus Protocol Compatibility Daemon
 # The first argument will be replaced by the service by information on
 # the process requesting the proxy, we need a placeholder to keep the
 # space available for this.
-ExecStart=@rootlibexecdir@/systemd-bus-proxyd --drop-privileges --address=kernel:path=/dev/kdbus/0-system/bus --configuration=/etc/dbus-1/system.conf --configuration=/etc/dbus-1/system-local.conf --configuration=/etc/dbus-1/system.d/ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+ExecStart=@rootlibexecdir@/systemd-bus-proxyd --drop-privileges --address=kernel:path=/sys/fs/kdbus/0-system/bus --configuration=/etc/dbus-1/system.conf --configuration=/etc/dbus-1/system-local.conf --configuration=/etc/dbus-1/system.d/ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
 NotifyAccess=main
 CapabilityBoundingSet=CAP_IPC_OWNER CAP_SETUID CAP_SETGID CAP_SETPCAP
 PrivateTmp=yes
diff --git a/units/user/systemd-bus-proxyd@.service.in b/units/user/systemd-bus-proxyd@.service.in
index 2f4df7cb5a..48294db266 100644
--- a/units/user/systemd-bus-proxyd@.service.in
+++ b/units/user/systemd-bus-proxyd@.service.in
@@ -12,5 +12,5 @@ Description=Legacy D-Bus Protocol Compatibility Daemon
 # The first argument will be replaced by the service by information on
 # the process requesting the proxy, we need a placeholder to keep the
 # space available for this.
-ExecStart=@rootlibexecdir@/systemd-bus-proxyd --address=kernel:path=/dev/kdbus/%U-user/bus --configuration=/etc/dbus-1/session.conf --configuration=/etc/dbus-1/session-local.conf --configuration=/etc/dbus-1/session.d/ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+ExecStart=@rootlibexecdir@/systemd-bus-proxyd --address=kernel:path=/sys/fs/kdbus/%U-user/bus --configuration=/etc/dbus-1/session.conf --configuration=/etc/dbus-1/session-local.conf --configuration=/etc/dbus-1/session.d/ xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
 NotifyAccess=main