sd-bus: sync kdbus.h (ABI break)

In kdbus.h, the following details changed:

 * All commands gained a 'kernel_flags' field to report the flags supported
   by the driver. Before, this was done in the 'flags' field in a
   bidirectional way, which turned out to be a problem for the code in
   sd-bus, as many parts of it reuse the same ioctl struct more than once
   and consider them to be owned by userspace.

 * Name listings are now returned by a new struct instead of reusing struct
   kdbus_cmd_name for that matter. This way, we don't add more unneeded
   fields to it and make the API cleaner.

 * 'conn_flags' was renamed to 'flags' in struct kdbus_cmd_hello to make
   the API a bit more unified.

src/bus-proxyd/bus-proxyd.c

@@ -734,7 +734,7 @@ static int process_driver(sd_bus *a, sd_bus *b, sd_bus_message *m) {
                 struct kdbus_cmd_name_list cmd = {};
                 struct kdbus_name_list *name_list;
                 struct kdbus_cmd_free cmd_free;
-                struct kdbus_cmd_name *name;
+                struct kdbus_name_info *name;
                 _cleanup_strv_free_ char **owners = NULL;
                 _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
                 char *arg0;

src/libsystemd/sd-bus/bus-control.c

@@ -243,7 +243,7 @@ static int kernel_cmd_free(sd_bus *bus, uint64_t offset)
 static int kernel_get_list(sd_bus *bus, uint64_t flags, char ***x) {
         struct kdbus_cmd_name_list cmd = {};
         struct kdbus_name_list *name_list;
-        struct kdbus_cmd_name *name;
+        struct kdbus_name_info *name;
         uint64_t previous_id = 0;
         int r;
 

src/libsystemd/sd-bus/bus-kernel.c

@@ -714,7 +714,7 @@ int bus_kernel_take_fd(sd_bus *b) {
 
         hello = alloca0_align(sz, 8);
         hello->size = sz;
-        hello->conn_flags = b->hello_flags;
+        hello->flags = b->hello_flags;
         hello->attach_flags = b->attach_flags;
         hello->pool_size = KDBUS_POOL_SIZE;
 
@@ -769,7 +769,7 @@ int bus_kernel_take_fd(sd_bus *b) {
 
         b->is_kernel = true;
         b->bus_client = true;
-        b->can_fds = !!(hello->conn_flags & KDBUS_HELLO_ACCEPT_FD);
+        b->can_fds = !!(hello->flags & KDBUS_HELLO_ACCEPT_FD);
         b->message_version = 2;
         b->message_endian = BUS_NATIVE_ENDIAN;
 
@@ -820,7 +820,6 @@ static void close_kdbus_msg(sd_bus *bus, struct kdbus_msg *k) {
 
 int bus_kernel_write_message(sd_bus *bus, sd_bus_message *m, bool hint_sync_call) {
         int r;
-        uint64_t flags;
 
         assert(bus);
         assert(m);
@@ -843,12 +842,7 @@ int bus_kernel_write_message(sd_bus *bus, sd_bus_message *m, bool hint_sync_call
         if (hint_sync_call)
                 m->kdbus->flags |= KDBUS_MSG_FLAGS_EXPECT_REPLY|KDBUS_MSG_FLAGS_SYNC_REPLY;
 
-        /* The kernel will return the set of supported flags in m->kdbus->flags.
-         * Save the current message flags before issuing the ioctl, and restore them
-         * afterwards */
-        flags = m->kdbus->flags;
         r = ioctl(bus->output_fd, KDBUS_CMD_MSG_SEND, m->kdbus);
-        m->kdbus->flags = flags;
         if (r < 0) {
                 _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
                 sd_bus_message *reply;
@@ -1559,7 +1553,7 @@ int bus_kernel_make_starter(
         }
 
         hello->size = size;
-        hello->conn_flags =
+        hello->flags =
                 (activating ? KDBUS_HELLO_ACTIVATOR : KDBUS_HELLO_POLICY_HOLDER) |
                 (accept_fd ? KDBUS_HELLO_ACCEPT_FD : 0);
         hello->pool_size = KDBUS_POOL_SIZE;

src/libsystemd/sd-bus/kdbus.h

@@ -373,7 +373,8 @@ enum kdbus_payload_type {
 /**
  * struct kdbus_msg - the representation of a kdbus message
  * @size:		Total size of the message
- * @flags:		Message flags (KDBUS_MSG_FLAGS_*)
+ * @flags:		Message flags (KDBUS_MSG_FLAGS_*), userspace → kernel
+ * @kernel_flags:	Supported message flags, kernel → userspace
  * @priority:		Message queue priority value
  * @dst_id:		64-bit ID of the destination connection
  * @src_id:		64-bit ID of the source connection
@@ -395,6 +396,7 @@ enum kdbus_payload_type {
 struct kdbus_msg {
 	__u64 size;
 	__u64 flags;
+	__u64 kernel_flags;
 	__s64 priority;
 	__u64 dst_id;
 	__u64 src_id;
@@ -429,7 +431,8 @@ enum kdbus_recv_flags {
 
 /**
  * struct kdbus_cmd_recv - struct to de-queue a buffered message
- * @flags:		KDBUS_RECV_* flags
+ * @flags:		KDBUS_RECV_* flags, userspace → kernel
+ * @kernel_flags:	Supported KDBUS_RECV_* flags, kernel → userspace
  * @priority:		Minimum priority of the messages to de-queue. Lowest
  *			values have the highest priority.
  * @offset:		Returned offset in the pool where the message is
@@ -440,6 +443,7 @@ enum kdbus_recv_flags {
  */
 struct kdbus_cmd_recv {
 	__u64 flags;
+	__u64 kernel_flags;
 	__s64 priority;
 	__u64 offset;
 } __attribute__((aligned(8)));
@@ -458,15 +462,17 @@ struct kdbus_cmd_cancel {
 
 /**
  * struct kdbus_cmd_free - struct to free a slice of memory in the pool
- * @offset		The offset of the memory slice, as returned by other
+ * @offset:		The offset of the memory slice, as returned by other
  *			ioctls
- * @flags		Flags for the free command. Currently unused.
+ * @flags:		Flags for the free command, userspace → kernel
+ * @kernel_flags:	Supported flags of the free command, userspace → kernel
  *
  * This struct is used with the KDBUS_CMD_FREE ioctl.
  */
 struct kdbus_cmd_free {
 	__u64 offset;
 	__u64 flags;
+	__u64 kernel_flags;
 } __attribute__((aligned(8)));
 
 /**
@@ -557,7 +563,8 @@ enum kdbus_attach_flags {
 /**
  * struct kdbus_cmd_hello - struct to say hello to kdbus
  * @size:		The total size of the structure
- * @conn_flags:		Connection flags (KDBUS_HELLO_*).
+ * @flags:		Connection flags (KDBUS_HELLO_*), userspace → kernel
+ * @kernel_flags:	Supported connection flags, kernel → userspace
  * @attach_flags:	Mask of metadata to attach to each message sent
  *			(KDBUS_ATTACH_*)
  * @bus_flags:		The flags field copied verbatim from the original
@@ -576,7 +583,8 @@ enum kdbus_attach_flags {
  */
 struct kdbus_cmd_hello {
 	__u64 size;
-	__u64 conn_flags;
+	__u64 flags;
+	__u64 kernel_flags;
 	__u64 attach_flags;
 	__u64 bus_flags;
 	__u64 id;
@@ -599,7 +607,9 @@ enum kdbus_make_flags {
 /**
  * struct kdbus_cmd_make - struct to make a bus, an endpoint or a domain
  * @size:		The total size of the struct
- * @flags:		Properties for the bus/ep/domain to create
+ * @flags:		Properties for the bus/ep/domain to create,
+ *			userspace → kernel
+ * @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
@@ -608,6 +618,7 @@ enum kdbus_make_flags {
 struct kdbus_cmd_make {
 	__u64 size;
 	__u64 flags;
+	__u64 kernel_flags;
 	struct kdbus_item items[0];
 } __attribute__((aligned(8)));
 
@@ -630,9 +641,9 @@ enum kdbus_name_flags {
 /**
  * struct kdbus_cmd_name - struct to describe a well-known name
  * @size:		The total size of the struct
- * @flags:		Flags for a name entry (KDBUS_NAME_*)
- * @owner_id:		The current owner of the name
- * @conn_flags:		The flags of the owning connection (KDBUS_HELLO_*)
+ * @flags:		Flags for a name entry (KDBUS_NAME_*),
+ *			userspace → kernel, kernel → userspace
+ * @kernel_flags:	Supported flags for a name entry, kernel → userspace
  * @items:		Item list, containing the well-known name as
  *			KDBUS_ITEM_NAME
  *
@@ -641,8 +652,26 @@ enum kdbus_name_flags {
 struct kdbus_cmd_name {
 	__u64 size;
 	__u64 flags;
-	__u64 owner_id;
+	__u64 kernel_flags;
+	struct kdbus_item items[0];
+} __attribute__((aligned(8)));
+
+/**
+ * struct kdbus_name_info - struct to describe a well-known name
+ * @size:		The total size of the struct
+ * @flags:		Flags for a name entry (KDBUS_NAME_*),
+ * @conn_flags:		The flags of the owning connection (KDBUS_HELLO_*)
+ * @owner_id:		The current owner of the name
+ * @items:		Item list, containing the well-known name as
+ *			KDBUS_ITEM_NAME
+ *
+ * This structure is used as return struct for the KDBUS_CMD_NAME_LIST ioctl.
+ */
+struct kdbus_name_info {
+	__u64 size;
+	__u64 flags;
 	__u64 conn_flags;
+	__u64 owner_id;
 	struct kdbus_item items[0];
 } __attribute__((aligned(8)));
 
@@ -662,7 +691,9 @@ enum kdbus_name_list_flags {
 
 /**
  * struct kdbus_cmd_name_list - request a list of name entries
- * @flags:		Flags for the query (KDBUS_NAME_LIST_*)
+ * @flags:		Flags for the query (KDBUS_NAME_LIST_*),
+ * 			userspace → kernel
+ * @kernel_flags:	Supported flags for queries, kernel → userspace
  * @offset:		The returned offset in the caller's pool buffer.
  *			The user must use KDBUS_CMD_FREE to free the
  *			allocated memory.
@@ -671,6 +702,7 @@ enum kdbus_name_list_flags {
  */
 struct kdbus_cmd_name_list {
 	__u64 flags;
+	__u64 kernel_flags;
 	__u64 offset;
 } __attribute__((aligned(8)));
 
@@ -684,13 +716,14 @@ struct kdbus_cmd_name_list {
  */
 struct kdbus_name_list {
 	__u64 size;
-	struct kdbus_cmd_name names[0];
+	struct kdbus_name_info names[0];
 };
 
 /**
  * struct kdbus_cmd_conn_info - struct used for KDBUS_CMD_CONN_INFO ioctl
  * @size:		The total size of the struct
- * @flags:		KDBUS_ATTACH_* flags
+ * @flags:		KDBUS_ATTACH_* flags, userspace → kernel
+ * @kernel_flags:	Supported KDBUS_ATTACH_* flags, kernel → userspace
  * @id:			The 64-bit ID of the connection. If set to zero, passing
  *			@name is required. kdbus will look up the name to
  *			determine the ID in this case.
@@ -707,6 +740,7 @@ struct kdbus_name_list {
 struct kdbus_cmd_conn_info {
 	__u64 size;
 	__u64 flags;
+	__u64 kernel_flags;
 	__u64 id;
 	__u64 offset;
 	struct kdbus_item items[0];
@@ -732,6 +766,8 @@ struct kdbus_conn_info {
 /**
  * struct kdbus_cmd_update - update flags of a connection
  * @size:		The total size of the struct
+ * @flags:		Flags for the update command, userspace → kernel
+ * @kernel_flags:	Supported flags for this command, kernel → userspace
  * @items:		A list of struct kdbus_item
  *
  * This struct is used with the KDBUS_CMD_CONN_UPDATE ioctl.
@@ -739,6 +775,7 @@ struct kdbus_conn_info {
 struct kdbus_cmd_update {
 	__u64 size;
 	__u64 flags;
+	__u64 kernel_flags;
 	struct kdbus_item items[0];
 } __attribute__((aligned(8)));
 
@@ -757,6 +794,9 @@ enum kdbus_cmd_match_flags {
  * @size:		The total size of the struct
  * @cookie:		Userspace supplied cookie. When removing, the cookie
  *			identifies the match to remove
+ * @flags:		Flags for match command (KDBUS_MATCH_*),
+ *			userspace → kernel
+ * @kernel_flags:	Supported flags of the used command, kernel → userspace
  * @items:		A list of items for additional information
  *
  * This structure is used with the KDBUS_CMD_ADD_MATCH and
@@ -766,6 +806,7 @@ struct kdbus_cmd_match {
 	__u64 size;
 	__u64 cookie;
 	__u64 flags;
+	__u64 kernel_flags;
 	struct kdbus_item items[0];
 } __attribute__((aligned(8)));