From 923e6c1659f58d2094f3d83a420b1793b8650430 Mon Sep 17 00:00:00 2001 From: Dagan Martinez Date: Fri, 1 Oct 2021 10:17:18 -0400 Subject: [PATCH] gatt: Allow GATT server to dicate CCC permissions Allow a GATT server to impose write permissions/restrictions on a CCC by setting additional `X-notify` and `X-indicate` flags on its associated characteristic. This allows a developer to require encryption/authentication in order for a GATT client to subscribe to server-initiated updates. ``` [bluetooth]# register-characteristic\ 4b75f0f8-1f23-46b1-900c-5bbabcd5ca93 encrypt-read,encrypt-notify [NEW] Characteristic (Handle 0x0000) /org/bluez/app/service0/chrc17 4b75f0f8-1f23-46b1-900c-5bbabcd5ca93 Vendor specific [/org/bluez/app/service0/chrc17] Enter value: 42 ``` Signed-off-by: Anuj Jain Signed-off-by: Ayush Garg --- src/gatt-database.c | 52 ++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 42 insertions(+), 10 deletions(-) diff --git a/src/gatt-database.c b/src/gatt-database.c index fb66bf7..084d33d 100644 --- a/src/gatt-database.c +++ b/src/gatt-database.c @@ -115,6 +115,7 @@ struct external_chrc { uint8_t props; uint8_t ext_props; uint32_t perm; + uint32_t ccc_perm; uint16_t mtu; struct io *write_io; struct io *notify_io; @@ -1236,7 +1237,7 @@ static struct gatt_db_attribute * service_add_ccc(struct gatt_db_attribute *service, struct btd_gatt_database *database, btd_gatt_database_ccc_write_t write_callback, - void *user_data, + void *user_data, uint32_t perm, btd_gatt_database_destroy_t destroy) { struct gatt_db_attribute *ccc; @@ -1245,9 +1246,14 @@ service_add_ccc(struct gatt_db_attribute *service, ccc_cb = new0(struct ccc_cb_data, 1); + /* + * Provide a way for the permissions on a characteristic to dictate + * the permissions on the CCC + */ + perm |= BT_ATT_PERM_READ | BT_ATT_PERM_WRITE; + bt_uuid16_create(&uuid, GATT_CLIENT_CHARAC_CFG_UUID); - ccc = gatt_db_service_add_descriptor(service, &uuid, - BT_ATT_PERM_READ | BT_ATT_PERM_WRITE, + ccc = gatt_db_service_add_descriptor(service, &uuid, perm, gatt_ccc_read_cb, gatt_ccc_write_cb, database); if (!ccc) { error("Failed to create CCC entry in database"); @@ -1448,7 +1454,7 @@ static void populate_gatt_service(struct btd_gatt_database *database) NULL, NULL, database); database->svc_chngd_ccc = service_add_ccc(service, database, NULL, NULL, - NULL); + 0, NULL); bt_uuid16_create(&uuid, GATT_CHARAC_CLI_FEAT); database->cli_feat = gatt_db_service_add_characteristic(service, @@ -2037,11 +2043,18 @@ static bool incr_attr_count(struct external_service *service, uint16_t incr) static bool parse_chrc_flags(DBusMessageIter *array, uint8_t *props, uint8_t *ext_props, uint32_t *perm, + uint32_t *ccc_perm, bool *req_prep_authorization) { const char *flag; - *props = *ext_props = 0; + if (!props || !ext_props || !perm || !ccc_perm) + return false; + + *props = 0; + *ext_props = 0; + *perm = 0; + *ccc_perm = 0; do { if (dbus_message_iter_get_arg_type(array) != DBUS_TYPE_STRING) @@ -2094,6 +2107,24 @@ static bool parse_chrc_flags(DBusMessageIter *array, uint8_t *props, *perm |= BT_ATT_PERM_WRITE | BT_ATT_PERM_WRITE_SECURE; } else if (!strcmp("authorize", flag)) { *req_prep_authorization = true; + } else if (!strcmp("encrypt-notify", flag)) { + *ccc_perm |= BT_ATT_PERM_WRITE_ENCRYPT; + *props |= BT_GATT_CHRC_PROP_NOTIFY; + } else if (!strcmp("encrypt-authenticated-notify", flag)) { + *ccc_perm |= BT_ATT_PERM_WRITE_AUTHEN; + *props |= BT_GATT_CHRC_PROP_NOTIFY; + } else if (!strcmp("secure-notify", flag)) { + *ccc_perm |= BT_ATT_PERM_WRITE_SECURE; + *props |= BT_GATT_CHRC_PROP_NOTIFY; + } else if (!strcmp("encrypt-indicate", flag)) { + *ccc_perm |= BT_ATT_PERM_WRITE_ENCRYPT; + *props |= BT_GATT_CHRC_PROP_INDICATE; + } else if (!strcmp("encrypt-authenticated-indicate", flag)) { + *ccc_perm |= BT_ATT_PERM_WRITE_AUTHEN; + *props |= BT_GATT_CHRC_PROP_INDICATE; + } else if (!strcmp("secure-indicate", flag)) { + *ccc_perm |= BT_ATT_PERM_WRITE_SECURE; + *props |= BT_GATT_CHRC_PROP_INDICATE; } else { error("Invalid characteristic flag: %s", flag); return false; @@ -2147,7 +2178,8 @@ static bool parse_desc_flags(DBusMessageIter *array, uint32_t *perm, } static bool parse_flags(GDBusProxy *proxy, uint8_t *props, uint8_t *ext_props, - uint32_t *perm, bool *req_prep_authorization) + uint32_t *perm, uint32_t *ccc_perm, + bool *req_prep_authorization) { DBusMessageIter iter, array; const char *iface; @@ -2164,7 +2196,7 @@ static bool parse_flags(GDBusProxy *proxy, uint8_t *props, uint8_t *ext_props, if (!strcmp(iface, GATT_DESC_IFACE)) return parse_desc_flags(&array, perm, req_prep_authorization); - return parse_chrc_flags(&array, props, ext_props, perm, + return parse_chrc_flags(&array, props, ext_props, perm, ccc_perm, req_prep_authorization); } @@ -2214,7 +2246,7 @@ static struct external_chrc *chrc_create(struct gatt_app *app, * created. */ if (!parse_flags(proxy, &chrc->props, &chrc->ext_props, &chrc->perm, - &chrc->req_prep_authorization)) { + &chrc->ccc_perm, &chrc->req_prep_authorization)) { error("Failed to parse characteristic properties"); goto fail; } @@ -2296,7 +2328,7 @@ static struct external_desc *desc_create(struct gatt_app *app, * Parse descriptors flags here since they are used to * determine the permission the descriptor should have */ - if (!parse_flags(proxy, NULL, NULL, &desc->perm, + if (!parse_flags(proxy, NULL, NULL, &desc->perm, NULL, &desc->req_prep_authorization)) { error("Failed to parse characteristic properties"); goto fail; @@ -3457,7 +3489,7 @@ static bool database_add_ccc(struct external_service *service, return true; chrc->ccc = service_add_ccc(service->attrib, service->app->database, - ccc_write_cb, chrc, NULL); + ccc_write_cb, chrc, chrc->ccc_perm, NULL); if (!chrc->ccc) { error("Failed to create CCC entry for characteristic"); return false; -- 2.7.4