linux/drivers/char/hw_random/core.c

/*
 * hw_random/core.c: HWRNG core API
 *
 * Copyright 2006 Michael Buesch <[email protected]>
 * Copyright 2005 (c) MontaVista Software, Inc.
 *
 * Please read Documentation/admin-guide/hw_random.rst for details on use.
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/hw_random.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/uaccess.h>

#define RNG_MODULE_NAME …

#define RNG_BUFFER_SIZE …

static struct hwrng *current_rng;
/* the current rng has been explicitly chosen by user via sysfs */
static int cur_rng_set_by_user;
static struct task_struct *hwrng_fill;
/* list of registered rngs */
static LIST_HEAD(rng_list);
/* Protects rng_list and current_rng */
static DEFINE_MUTEX(rng_mutex);
/* Protects rng read functions, data_avail, rng_buffer and rng_fillbuf */
static DEFINE_MUTEX(reading_mutex);
static int data_avail;
static u8 *rng_buffer, *rng_fillbuf;
static unsigned short current_quality;
static unsigned short default_quality = …; /* default to maximum */

module_param(current_quality, ushort, 0644);
MODULE_PARM_DESC(…) …;
module_param(default_quality, ushort, 0644);
MODULE_PARM_DESC(…) …;

static void drop_current_rng(void);
static int hwrng_init(struct hwrng *rng);
static int hwrng_fillfn(void *unused);

static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
			       int wait);

static size_t rng_buffer_size(void)
{ … }

static inline void cleanup_rng(struct kref *kref)
{ … }

static int set_current_rng(struct hwrng *rng)
{ … }

static void drop_current_rng(void)
{ … }

/* Returns ERR_PTR(), NULL or refcounted hwrng */
static struct hwrng *get_current_rng_nolock(void)
{ … }

static struct hwrng *get_current_rng(void)
{ … }

static void put_rng(struct hwrng *rng)
{ … }

static int hwrng_init(struct hwrng *rng)
{ … }

static int rng_dev_open(struct inode *inode, struct file *filp)
{ … }

static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
			int wait) { … }

static ssize_t rng_dev_read(struct file *filp, char __user *buf,
			    size_t size, loff_t *offp)
{ … }

static const struct file_operations rng_chrdev_ops = …;

static const struct attribute_group *rng_dev_groups[];

static struct miscdevice rng_miscdev = …;

static int enable_best_rng(void)
{ … }

static ssize_t rng_current_store(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf, size_t len)
{ … }

static ssize_t rng_current_show(struct device *dev,
				struct device_attribute *attr,
				char *buf)
{ … }

static ssize_t rng_available_show(struct device *dev,
				  struct device_attribute *attr,
				  char *buf)
{ … }

static ssize_t rng_selected_show(struct device *dev,
				 struct device_attribute *attr,
				 char *buf)
{ … }

static ssize_t rng_quality_show(struct device *dev,
				struct device_attribute *attr,
				char *buf)
{ … }

static ssize_t rng_quality_store(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf, size_t len)
{ … }

static DEVICE_ATTR_RW(rng_current);
static DEVICE_ATTR_RO(rng_available);
static DEVICE_ATTR_RO(rng_selected);
static DEVICE_ATTR_RW(rng_quality);

static struct attribute *rng_dev_attrs[] = …;

ATTRIBUTE_GROUPS(…);

static int hwrng_fillfn(void *unused)
{ … }

int hwrng_register(struct hwrng *rng)
{ … }
EXPORT_SYMBOL_GPL(…);

void hwrng_unregister(struct hwrng *rng)
{ … }
EXPORT_SYMBOL_GPL(…);

static void devm_hwrng_release(struct device *dev, void *res)
{ … }

static int devm_hwrng_match(struct device *dev, void *res, void *data)
{ … }

int devm_hwrng_register(struct device *dev, struct hwrng *rng)
{ … }
EXPORT_SYMBOL_GPL(…);

void devm_hwrng_unregister(struct device *dev, struct hwrng *rng)
{ … }
EXPORT_SYMBOL_GPL(…);

long hwrng_msleep(struct hwrng *rng, unsigned int msecs)
{ … }
EXPORT_SYMBOL_GPL(…);

long hwrng_yield(struct hwrng *rng)
{ … }
EXPORT_SYMBOL_GPL(…);

static int __init hwrng_modinit(void)
{ … }

static void __exit hwrng_modexit(void)
{ … }

fs_initcall(hwrng_modinit); /* depends on misc_register() */
module_exit(hwrng_modexit);

MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;