Add support for requiring min key size for access GATT characteristics

index 5ae19a8e5..08541c424 100644
@@ -128,7 +128,7 @@ static struct gatt_conn *gatt_conn_new(int fd)
 
 	bt_att_set_security(conn->att, BT_SECURITY_MEDIUM);
 
-	conn->gatt = bt_gatt_server_new(gatt_db, conn->att, mtu);
+	conn->gatt = bt_gatt_server_new(gatt_db, conn->att, mtu, 0);
 	if (!conn->gatt) {
 		fprintf(stderr, "Failed to create GATT server\n");
 		bt_att_unref(conn->att);

86 lines not on this page · raw message

index 7c7196ca1..f3c5e7925 100644
@@ -243,6 +243,7 @@ struct btd_device {
 
 	struct csrk_info *local_csrk;
 	struct csrk_info *remote_csrk;
+	uint8_t ltk_enc_size;
 
 	sdp_list_t	*tmp_records;
 

@@ -1460,6 +1461,12 @@ bool device_is_disconnecting(struct btd_device *device)
 	return device->disconn_timer > 0;
 }
 
+void device_set_ltk_enc_size(struct btd_device *device, uint8_t enc_size)
+{
+	device->ltk_enc_size = enc_size;
+	bt_att_set_enc_key_size(device->att, device->ltk_enc_size);
+}
+
 static void device_set_auto_connect(struct btd_device *device, gboolean enable)
 {
 	char addr[18];

@@ -4834,10 +4841,14 @@ static void gatt_server_init(struct btd_device *device, struct gatt_db *db)
 
 	gatt_server_cleanup(device);
 
-	device->server = bt_gatt_server_new(db, device->att, device->att_mtu);
-	if (!device->server)
+	device->server = bt_gatt_server_new(db, device->att, device->att_mtu,
+						main_opts.min_enc_key_size);
+	if (!device->server) {
 		error("Failed to initialize bt_gatt_server");
+		return;
+	}
 
+	bt_att_set_enc_key_size(device->att, device->ltk_enc_size);
 	bt_gatt_server_set_debug(device->server, gatt_debug, NULL, NULL);
 }
 

index bc046f780..306c813fc 100644
@@ -130,6 +130,7 @@ void device_add_connection(struct btd_device *dev, uint8_t bdaddr_type);
 void device_remove_connection(struct btd_device *device, uint8_t bdaddr_type);
 void device_request_disconnect(struct btd_device *device, DBusMessage *msg);
 bool device_is_disconnecting(struct btd_device *device);
+void device_set_ltk_enc_size(struct btd_device *device, uint8_t enc_size);
 
 typedef void (*disconnect_watch) (struct btd_device *device, gboolean removal,
 					void *user_data);

index 62e2bd606..2c2b89d9c 100644
@@ -54,6 +54,8 @@ struct main_opts {
 
 	bt_mode_t	mode;
 	bt_gatt_cache_t gatt_cache;
+
+	uint8_t		min_enc_key_size;
 };
 
 extern struct main_opts main_opts;

index 21f0b14a4..7e6af42cd 100644
@@ -103,6 +103,7 @@ static const char *policy_options[] = {
 
 static const char *gatt_options[] = {
 	"Cache",
+	"MinEncKeySize",
 	NULL
 };
 

@@ -402,12 +403,22 @@ static void parse_config(GKeyFile *config)
 	if (err) {
 		g_clear_error(&err);
 		main_opts.gatt_cache = BT_GATT_CACHE_ALWAYS;
-		return;
+	} else {
+		main_opts.gatt_cache = parse_gatt_cache(str);
+		g_free(str);
 	}
 
-	main_opts.gatt_cache = parse_gatt_cache(str);
+	val = g_key_file_get_integer(config, "GATT",
+						"MinEncKeySize", &err);
+	if (err) {
+		DBG("%s", err->message);
+		g_clear_error(&err);
+	} else {
+		DBG("MinEncKeySize=%d", val);
 
-	g_free(str);
+		if (val >=7 && val <= 16)
+			main_opts.min_enc_key_size = val;
+	}
 }
 
 static void init_defaults(void)

index 0aab246d6..8bf3f4611 100644
@@ -55,6 +55,7 @@ struct bt_att {
 	struct io *io;
 	bool io_on_l2cap;
 	int io_sec_level;		/* Only used for non-L2CAP */
+	uint8_t enc_size;
 
 	struct queue *req_queue;	/* Queued ATT protocol requests */
 	struct att_send_op *pending_req;

@@ -602,7 +603,7 @@ static bool change_security(struct bt_att *att, uint8_t ecode)
 	if (att->io_sec_level != BT_ATT_SECURITY_AUTO)
 		return false;
 
-	security = bt_att_get_security(att);
+	security = bt_att_get_security(att, NULL);
 
 	if (ecode == BT_ATT_ERROR_INSUFFICIENT_ENCRYPTION &&
 					security < BT_ATT_SECURITY_MEDIUM) {

@@ -1454,7 +1455,7 @@ bool bt_att_unregister_all(struct bt_att *att)
 	return true;
 }
 
-int bt_att_get_security(struct bt_att *att)
+int bt_att_get_security(struct bt_att *att, uint8_t *enc_size)
 {
 	struct bt_security sec;
 	socklen_t len;

@@ -1462,14 +1463,21 @@ int bt_att_get_security(struct bt_att *att)
 	if (!att)
 		return -EINVAL;
 
-	if (!att->io_on_l2cap)
+	if (!att->io_on_l2cap) {
+		if (enc_size)
+			*enc_size = att->enc_size;
+
 		return att->io_sec_level;
+	}
 
 	memset(&sec, 0, sizeof(sec));
 	len = sizeof(sec);
 	if (getsockopt(att->fd, SOL_BLUETOOTH, BT_SECURITY, &sec, &len) < 0)
 		return -EIO;
 
+	if (enc_size)
+		*enc_size = att->enc_size;
+
 	return sec.level;
 }
 

@@ -1496,6 +1504,14 @@ bool bt_att_set_security(struct bt_att *att, int level)
 	return true;
 }
 
+void bt_att_set_enc_key_size(struct bt_att *att, uint8_t enc_size)
+{
+	if (!att)
+		return;
+
+	att->enc_size = enc_size;
+}
+
 static bool sign_set_key(struct sign_info **sign, uint8_t key[16],
 				bt_att_counter_func_t func, void *user_data)
 {

index 7bffee7d6..49d93269b 100644
@@ -84,8 +84,9 @@ bool bt_att_unregister_disconnect(struct bt_att *att, unsigned int id);
 
 bool bt_att_unregister_all(struct bt_att *att);
 
-int bt_att_get_security(struct bt_att *att);
+int bt_att_get_security(struct bt_att *att, uint8_t *enc_size);
 bool bt_att_set_security(struct bt_att *att, int level);
+void bt_att_set_enc_key_size(struct bt_att *att, uint8_t enc_size);
 
 bool bt_att_set_local_key(struct bt_att *att, uint8_t sign_key[16],
 			bt_att_counter_func_t func, void *user_data);

index e1d489d32..a5c7b1485 100644
@@ -2466,7 +2466,7 @@ unsigned int bt_gatt_client_write_without_response(
 
 	/* Only use signed write if unencrypted */
 	if (signed_write) {
-		security = bt_att_get_security(client->att);
+		security = bt_att_get_security(client->att, NULL);
 		op = security > BT_SECURITY_LOW ?  BT_ATT_OP_WRITE_CMD :
 						BT_ATT_OP_SIGNED_WRITE_CMD;
 	} else

@@ -3182,5 +3182,5 @@ int bt_gatt_client_get_security(struct bt_gatt_client *client)
 	if (!client)
 		return -1;
 
-	return bt_att_get_security(client->att);
+	return bt_att_get_security(client->att, NULL);
 }

index faa56abeb..f6c98e277 100644
@@ -103,6 +103,8 @@ struct bt_gatt_server {
 	unsigned int prep_write_id;
 	unsigned int exec_write_id;
 
+	uint8_t min_enc_size;
+
 	struct queue *prep_queue;
 	unsigned int max_prep_queue_len;
 

@@ -382,6 +384,7 @@ done:
 static uint8_t check_permissions(struct bt_gatt_server *server,
 				struct gatt_db_attribute *attr, uint32_t mask)
 {
+	uint8_t enc_size;
 	uint32_t perm;
 	int security;
 

@@ -397,15 +400,30 @@ static uint8_t check_permissions(struct bt_gatt_server *server,
 	if (!perm)
 		return 0;
 
-	security = bt_att_get_security(server->att);
-	if (perm & BT_ATT_PERM_SECURE && security < BT_ATT_SECURITY_FIPS)
-		return BT_ATT_ERROR_AUTHENTICATION;
+	security = bt_att_get_security(server->att, &enc_size);
+	if (perm & BT_ATT_PERM_SECURE) {
+		if (security < BT_ATT_SECURITY_FIPS)
+			return BT_ATT_ERROR_AUTHENTICATION;
+
+		if (server->min_enc_size && server->min_enc_size > enc_size)
+			return BT_ATT_ERROR_INSUFFICIENT_ENCRYPTION_KEY_SIZE;
+	}
 
-	if (perm & BT_ATT_PERM_AUTHEN && security < BT_ATT_SECURITY_HIGH)
-		return BT_ATT_ERROR_AUTHENTICATION;
+	if (perm & BT_ATT_PERM_AUTHEN) {
+		if (security < BT_ATT_SECURITY_HIGH)
+			return BT_ATT_ERROR_AUTHENTICATION;
 
-	if (perm & BT_ATT_PERM_ENCRYPT && security < BT_ATT_SECURITY_MEDIUM)
-		return BT_ATT_ERROR_INSUFFICIENT_ENCRYPTION;
+		if (server->min_enc_size && server->min_enc_size > enc_size)
+			return BT_ATT_ERROR_INSUFFICIENT_ENCRYPTION_KEY_SIZE;
+	}
+
+	if (perm & BT_ATT_PERM_ENCRYPT) {
+		if (security < BT_ATT_SECURITY_MEDIUM)
+			return BT_ATT_ERROR_INSUFFICIENT_ENCRYPTION;
+
+		if (server->min_enc_size && server->min_enc_size > enc_size)
+			return BT_ATT_ERROR_INSUFFICIENT_ENCRYPTION_KEY_SIZE;
+	}
 
 	return 0;
 }

@@ -1481,7 +1499,8 @@ static bool gatt_server_register_att_handlers(struct bt_gatt_server *server)
 }
 
 struct bt_gatt_server *bt_gatt_server_new(struct gatt_db *db,
-					struct bt_att *att, uint16_t mtu)
+					struct bt_att *att, uint16_t mtu,
+					uint8_t min_enc_size)
 {
 	struct bt_gatt_server *server;
 

@@ -1494,6 +1513,7 @@ struct bt_gatt_server *bt_gatt_server_new(struct gatt_db *db,
 	server->mtu = MAX(mtu, BT_ATT_DEFAULT_LE_MTU);
 	server->max_prep_queue_len = DEFAULT_MAX_PREP_QUEUE_LEN;
 	server->prep_queue = queue_new();
+	server->min_enc_size = min_enc_size;
 
 	if (!gatt_server_register_att_handlers(server)) {
 		bt_gatt_server_free(server);

index 74a6c721e..d5d209350 100644
@@ -26,7 +26,8 @@
 struct bt_gatt_server;
 
 struct bt_gatt_server *bt_gatt_server_new(struct gatt_db *db,
-					struct bt_att *att, uint16_t mtu);
+					struct bt_att *att, uint16_t mtu,
+					uint8_t min_enc_size);
 uint16_t bt_gatt_server_get_mtu(struct bt_gatt_server *server);
 
 struct bt_gatt_server *bt_gatt_server_ref(struct bt_gatt_server *server);

index fadaff2ad..89812bd75 100644
@@ -583,7 +583,7 @@ static struct server *server_create(int fd, uint16_t mtu, bool hr_visible)
 		goto fail;
 	}
 
-	server->gatt = bt_gatt_server_new(server->db, server->att, mtu);
+	server->gatt = bt_gatt_server_new(server->db, server->att, mtu, 0);
 	if (!server->gatt) {
 		fprintf(stderr, "Failed to create GATT server\n");
 		goto fail;

index 5d79e94c0..c7e28f865 100644
@@ -667,7 +667,7 @@ static struct context *create_context(uint16_t mtu, gconstpointer data)
 		g_assert(context->server_db);
 
 		context->server = bt_gatt_server_new(context->server_db,
-							context->att, mtu);
+							context->att, mtu, 0);
 		g_assert(context->server);
 
 		bt_gatt_server_set_debug(context->server, print_debug,