/* * This module provides an interface to trigger and test firmware loading. * * It is designed to be used for basic evaluation of the firmware loading * subsystem (for example when validating firmware verification). It lacks * any extra dependencies, and will not normally be loaded by the system * unless explicitly requested by name. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/init.h> #include <linux/module.h> #include <linux/printk.h> #include <linux/completion.h> #include <linux/firmware.h> #include <linux/device.h> #include <linux/fs.h> #include <linux/miscdevice.h> #include <linux/slab.h> #include <linux/uaccess.h> static DEFINE_MUTEX(test_fw_mutex); static const struct firmware *test_firmware; static ssize_t test_fw_misc_read(struct file *f, char __user *buf, size_t size, loff_t *offset) { ssize_t rc = 0; mutex_lock(&test_fw_mutex); if (test_firmware) rc = simple_read_from_buffer(buf, size, offset, test_firmware->data, test_firmware->size); mutex_unlock(&test_fw_mutex); return rc; } static const struct file_operations test_fw_fops = { .owner = THIS_MODULE, .read = test_fw_misc_read, }; static ssize_t trigger_request_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { int rc; char *name; name = kstrndup(buf, count, GFP_KERNEL); if (!name) return -ENOSPC; pr_info("loading '%s'\n", name); mutex_lock(&test_fw_mutex); release_firmware(test_firmware); test_firmware = NULL; rc = request_firmware(&test_firmware, name, dev); if (rc) { pr_info("load of '%s' failed: %d\n", name, rc); goto out; } pr_info("loaded: %zu\n", test_firmware->size); rc = count; out: mutex_unlock(&test_fw_mutex); kfree(name); return rc; } static DEVICE_ATTR_WO(trigger_request); static DECLARE_COMPLETION(async_fw_done); static void trigger_async_request_cb(const struct firmware *fw, void *context) { test_firmware = fw; complete(&async_fw_done); } static ssize_t trigger_async_request_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { int rc; char *name; name = kstrndup(buf, count, GFP_KERNEL); if (!name) return -ENOSPC; pr_info("loading '%s'\n", name); mutex_lock(&test_fw_mutex); release_firmware(test_firmware); test_firmware = NULL; rc = request_firmware_nowait(THIS_MODULE, 1, name, dev, GFP_KERNEL, NULL, trigger_async_request_cb); if (rc) { pr_info("async load of '%s' failed: %d\n", name, rc); kfree(name); goto out; } /* Free 'name' ASAP, to test for race conditions */ kfree(name); wait_for_completion(&async_fw_done); if (test_firmware) { pr_info("loaded: %zu\n", test_firmware->size); rc = count; } else { pr_err("failed to async load firmware\n"); rc = -ENODEV; } out: mutex_unlock(&test_fw_mutex); return rc; } static DEVICE_ATTR_WO(trigger_async_request); static ssize_t trigger_custom_fallback_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { int rc; char *name; name = kstrndup(buf, count, GFP_KERNEL); if (!name) return -ENOSPC; pr_info("loading '%s' using custom fallback mechanism\n", name); mutex_lock(&test_fw_mutex); release_firmware(test_firmware); test_firmware = NULL; rc = request_firmware_nowait(THIS_MODULE, FW_ACTION_NOHOTPLUG, name, dev, GFP_KERNEL, NULL, trigger_async_request_cb); if (rc) { pr_info("async load of '%s' failed: %d\n", name, rc); kfree(name); goto out; } /* Free 'name' ASAP, to test for race conditions */ kfree(name); wait_for_completion(&async_fw_done); if (test_firmware) { pr_info("loaded: %zu\n", test_firmware->size); rc = count; } else { pr_err("failed to async load firmware\n"); rc = -ENODEV; } out: mutex_unlock(&test_fw_mutex); return rc; } static DEVICE_ATTR_WO(trigger_custom_fallback); #define TEST_FW_DEV_ATTR(name) &dev_attr_##name.attr static struct attribute *test_dev_attrs[] = { TEST_FW_DEV_ATTR(trigger_request), TEST_FW_DEV_ATTR(trigger_async_request), TEST_FW_DEV_ATTR(trigger_custom_fallback), NULL, }; ATTRIBUTE_GROUPS(test_dev); static struct miscdevice test_fw_misc_device = { .minor = MISC_DYNAMIC_MINOR, .name = "test_firmware", .fops = &test_fw_fops, .groups = test_dev_groups, }; static int __init test_firmware_init(void) { int rc; rc = misc_register(&test_fw_misc_device); if (rc) { pr_err("could not register misc device: %d\n", rc); return rc; } pr_warn("interface ready\n"); return 0; } module_init(test_firmware_init); static void __exit test_firmware_exit(void) { release_firmware(test_firmware); misc_deregister(&test_fw_misc_device); pr_warn("removed interface\n"); } module_exit(test_firmware_exit); MODULE_AUTHOR("Kees Cook <keescook@chromium.org>"); MODULE_LICENSE("GPL");