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/*
* 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");
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