crypto/jitterentropy-testing.c - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
 /*
  * Test interface for Jitter RNG.
  *
  * Copyright (C) 2023, Stephan Mueller <smueller@chronox.de>
  */

 #include <linux/debugfs.h>
 #include <linux/module.h>
 #include <linux/uaccess.h>

 #include "jitterentropy.h"

 #define JENT_TEST_RINGBUFFER_SIZE	(1<<10)
 #define JENT_TEST_RINGBUFFER_MASK	(JENT_TEST_RINGBUFFER_SIZE - 1)

 struct jent_testing {
 	u64 jent_testing_rb[JENT_TEST_RINGBUFFER_SIZE];
 	u32 rb_reader;
 	atomic_t rb_writer;
 	atomic_t jent_testing_enabled;
 	spinlock_t lock;
 	wait_queue_head_t read_wait;
 };

 static struct dentry *jent_raw_debugfs_root = NULL;

 /*************************** Generic Data Handling ****************************/

 /*
  * boot variable:
  * 0 ==> No boot test, gathering of runtime data allowed
  * 1 ==> Boot test enabled and ready for collecting data, gathering runtime
  *	 data is disabled
  * 2 ==> Boot test completed and disabled, gathering of runtime data is
  *	 disabled
  */

 static void jent_testing_reset(struct jent_testing *data)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&data->lock, flags);
 	data->rb_reader = 0;
 	atomic_set(&data->rb_writer, 0);
 	spin_unlock_irqrestore(&data->lock, flags);
 }

 static void jent_testing_data_init(struct jent_testing *data, u32 boot)
 {
 	/*
 	 * The boot time testing implies we have a running test. If the
 	 * caller wants to clear it, he has to unset the boot_test flag
 	 * at runtime via sysfs to enable regular runtime testing
 	 */
 	if (boot)
 		return;

 	jent_testing_reset(data);
 	atomic_set(&data->jent_testing_enabled, 1);
 	pr_warn("Enabling data collection\n");
 }

 static void jent_testing_fini(struct jent_testing *data, u32 boot)
 {
 	/* If we have boot data, we do not reset yet to allow data to be read */
 	if (boot)
 		return;

 	atomic_set(&data->jent_testing_enabled, 0);
 	jent_testing_reset(data);
 	pr_warn("Disabling data collection\n");
 }

 static bool jent_testing_store(struct jent_testing *data, u64 value,
 			       u32 *boot)
 {
 	unsigned long flags;

 	if (!atomic_read(&data->jent_testing_enabled) && (*boot != 1))
 		return false;

 	spin_lock_irqsave(&data->lock, flags);

 	/*
 	 * Disable entropy testing for boot time testing after ring buffer
 	 * is filled.
 	 */
 	if (*boot) {
 		if (((u32)atomic_read(&data->rb_writer)) >
 		     JENT_TEST_RINGBUFFER_SIZE) {
 			*boot = 2;
 			pr_warn_once("One time data collection test disabled\n");
 			spin_unlock_irqrestore(&data->lock, flags);
 			return false;
 		}

 		if (atomic_read(&data->rb_writer) == 1)
 			pr_warn("One time data collection test enabled\n");
 	}

 	data->jent_testing_rb[((u32)atomic_read(&data->rb_writer)) &
 			      JENT_TEST_RINGBUFFER_MASK] = value;
 	atomic_inc(&data->rb_writer);

 	spin_unlock_irqrestore(&data->lock, flags);

 	if (wq_has_sleeper(&data->read_wait))
 		wake_up_interruptible(&data->read_wait);

 	return true;
 }

 static bool jent_testing_have_data(struct jent_testing *data)
 {
 	return ((((u32)atomic_read(&data->rb_writer)) &
 		 JENT_TEST_RINGBUFFER_MASK) !=
 		 (data->rb_reader & JENT_TEST_RINGBUFFER_MASK));
 }

 static int jent_testing_reader(struct jent_testing *data, u32 *boot,
 			       u8 *outbuf, u32 outbuflen)
 {
 	unsigned long flags;
 	int collected_data = 0;

 	jent_testing_data_init(data, *boot);

 	while (outbuflen) {
 		u32 writer = (u32)atomic_read(&data->rb_writer);

 		spin_lock_irqsave(&data->lock, flags);

 		/* We have no data or reached the writer. */
 		if (!writer || (writer == data->rb_reader)) {

 			spin_unlock_irqrestore(&data->lock, flags);

 			/*
 			 * Now we gathered all boot data, enable regular data
 			 * collection.
 			 */
 			if (*boot) {
 				*boot = 0;
 				goto out;
 			}

 			wait_event_interruptible(data->read_wait,
 						 jent_testing_have_data(data));
 			if (signal_pending(current)) {
 				collected_data = -ERESTARTSYS;
 				goto out;
 			}

 			continue;
 		}

 		/* We copy out word-wise */
 		if (outbuflen < sizeof(u64)) {
 			spin_unlock_irqrestore(&data->lock, flags);
 			goto out;
 		}

 		memcpy(outbuf, &data->jent_testing_rb[data->rb_reader],
 		       sizeof(u64));
 		data->rb_reader++;

 		spin_unlock_irqrestore(&data->lock, flags);

 		outbuf += sizeof(u64);
 		outbuflen -= sizeof(u64);
 		collected_data += sizeof(u64);
 	}

 out:
 	jent_testing_fini(data, *boot);
 	return collected_data;
 }

 static int jent_testing_extract_user(struct file *file, char __user *buf,
 				     size_t nbytes, loff_t *ppos,
 				     int (*reader)(u8 *outbuf, u32 outbuflen))
 {
 	u8 *tmp, *tmp_aligned;
 	int ret = 0, large_request = (nbytes > 256);

 	if (!nbytes)
 		return 0;

 	/*
 	 * The intention of this interface is for collecting at least
 	 * 1000 samples due to the SP800-90B requirements. However, due to
 	 * memory and performance constraints, it is not desirable to allocate
 	 * 8000 bytes of memory. Instead, we allocate space for only 125
 	 * samples, which will allow the user to collect all 1000 samples using
 	 * 8 calls to this interface.
 	 */
 	tmp = kmalloc(125 * sizeof(u64) + sizeof(u64), GFP_KERNEL);
 	if (!tmp)
 		return -ENOMEM;

 	tmp_aligned = PTR_ALIGN(tmp, sizeof(u64));

 	while (nbytes) {
 		int i;

 		if (large_request && need_resched()) {
 			if (signal_pending(current)) {
 				if (ret == 0)
 					ret = -ERESTARTSYS;
 				break;
 			}
 			schedule();
 		}

 		i = min_t(int, nbytes, 125 * sizeof(u64));
 		i = reader(tmp_aligned, i);
 		if (i <= 0) {
 			if (i < 0)
 				ret = i;
 			break;
 		}
 		if (copy_to_user(buf, tmp_aligned, i)) {
 			ret = -EFAULT;
 			break;
 		}

 		nbytes -= i;
 		buf += i;
 		ret += i;
 	}

 	kfree_sensitive(tmp);

 	if (ret > 0)
 		*ppos += ret;

 	return ret;
 }

 /************** Raw High-Resolution Timer Entropy Data Handling **************/

 static u32 boot_raw_hires_test = 0;
 module_param(boot_raw_hires_test, uint, 0644);
 MODULE_PARM_DESC(boot_raw_hires_test,
 		 "Enable gathering boot time high resolution timer entropy of the first Jitter RNG entropy events");

 static struct jent_testing jent_raw_hires = {
 	.rb_reader = 0,
 	.rb_writer = ATOMIC_INIT(0),
 	.lock      = __SPIN_LOCK_UNLOCKED(jent_raw_hires.lock),
 	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(jent_raw_hires.read_wait)
 };

 int jent_raw_hires_entropy_store(__u64 value)
 {
 	return jent_testing_store(&jent_raw_hires, value, &boot_raw_hires_test);
 }
 EXPORT_SYMBOL(jent_raw_hires_entropy_store);

 static int jent_raw_hires_entropy_reader(u8 *outbuf, u32 outbuflen)
 {
 	return jent_testing_reader(&jent_raw_hires, &boot_raw_hires_test,
 				   outbuf, outbuflen);
 }

 static ssize_t jent_raw_hires_read(struct file *file, char __user *to,
 				   size_t count, loff_t *ppos)
 {
 	return jent_testing_extract_user(file, to, count, ppos,
 					 jent_raw_hires_entropy_reader);
 }

 static const struct file_operations jent_raw_hires_fops = {
 	.owner = THIS_MODULE,
 	.read = jent_raw_hires_read,
 };

 /******************************* Initialization *******************************/

 void jent_testing_init(void)
 {
 	jent_raw_debugfs_root = debugfs_create_dir(KBUILD_MODNAME, NULL);

 	debugfs_create_file_unsafe("jent_raw_hires", 0400,
 				   jent_raw_debugfs_root, NULL,
 				   &jent_raw_hires_fops);
 }
 EXPORT_SYMBOL(jent_testing_init);

 void jent_testing_exit(void)
 {
 	debugfs_remove_recursive(jent_raw_debugfs_root);
 }
 EXPORT_SYMBOL(jent_testing_exit);
	/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
	/*
	* Test interface for Jitter RNG.
	*
	* Copyright (C) 2023, Stephan Mueller <smueller@chronox.de>
	*/

	#include <linux/debugfs.h>
	#include <linux/module.h>
	#include <linux/uaccess.h>

	#include "jitterentropy.h"

	#define JENT_TEST_RINGBUFFER_SIZE (1<<10)
	#define JENT_TEST_RINGBUFFER_MASK (JENT_TEST_RINGBUFFER_SIZE - 1)

	struct jent_testing {
	u64 jent_testing_rb[JENT_TEST_RINGBUFFER_SIZE];
	u32 rb_reader;
	atomic_t rb_writer;
	atomic_t jent_testing_enabled;
	spinlock_t lock;
	wait_queue_head_t read_wait;
	};

	static struct dentry *jent_raw_debugfs_root = NULL;

	/************************* Generic Data Handling **************************/

	/*
	* boot variable:
	* 0 ==> No boot test, gathering of runtime data allowed
	* 1 ==> Boot test enabled and ready for collecting data, gathering runtime
	* data is disabled
	* 2 ==> Boot test completed and disabled, gathering of runtime data is
	* disabled
	*/

	static void jent_testing_reset(struct jent_testing *data)
	{
	unsigned long flags;

	spin_lock_irqsave(&data->lock, flags);
	data->rb_reader = 0;
	atomic_set(&data->rb_writer, 0);
	spin_unlock_irqrestore(&data->lock, flags);
	}

	static void jent_testing_data_init(struct jent_testing *data, u32 boot)
	{
	/*
	* The boot time testing implies we have a running test. If the
	* caller wants to clear it, he has to unset the boot_test flag
	* at runtime via sysfs to enable regular runtime testing
	*/
	if (boot)
	return;

	jent_testing_reset(data);
	atomic_set(&data->jent_testing_enabled, 1);
	pr_warn("Enabling data collection\n");
	}

	static void jent_testing_fini(struct jent_testing *data, u32 boot)
	{
	/* If we have boot data, we do not reset yet to allow data to be read */
	if (boot)
	return;

	atomic_set(&data->jent_testing_enabled, 0);
	jent_testing_reset(data);
	pr_warn("Disabling data collection\n");
	}

	static bool jent_testing_store(struct jent_testing *data, u64 value,
	u32 *boot)
	{
	unsigned long flags;

	if (!atomic_read(&data->jent_testing_enabled) && (*boot != 1))
	return false;

	spin_lock_irqsave(&data->lock, flags);

	/*
	* Disable entropy testing for boot time testing after ring buffer
	* is filled.
	*/
	if (*boot) {
	if (((u32)atomic_read(&data->rb_writer)) >
	JENT_TEST_RINGBUFFER_SIZE) {
	*boot = 2;
	pr_warn_once("One time data collection test disabled\n");
	spin_unlock_irqrestore(&data->lock, flags);
	return false;
	}

	if (atomic_read(&data->rb_writer) == 1)
	pr_warn("One time data collection test enabled\n");
	}

	data->jent_testing_rb[((u32)atomic_read(&data->rb_writer)) &
	JENT_TEST_RINGBUFFER_MASK] = value;
	atomic_inc(&data->rb_writer);

	spin_unlock_irqrestore(&data->lock, flags);

	if (wq_has_sleeper(&data->read_wait))
	wake_up_interruptible(&data->read_wait);

	return true;
	}

	static bool jent_testing_have_data(struct jent_testing *data)
	{
	return ((((u32)atomic_read(&data->rb_writer)) &
	JENT_TEST_RINGBUFFER_MASK) !=
	(data->rb_reader & JENT_TEST_RINGBUFFER_MASK));
	}

	static int jent_testing_reader(struct jent_testing data, u32 boot,
	u8 *outbuf, u32 outbuflen)
	{
	unsigned long flags;
	int collected_data = 0;

	jent_testing_data_init(data, *boot);

	while (outbuflen) {
	u32 writer = (u32)atomic_read(&data->rb_writer);

	spin_lock_irqsave(&data->lock, flags);

	/* We have no data or reached the writer. */
	if (!writer \|\| (writer == data->rb_reader)) {

	spin_unlock_irqrestore(&data->lock, flags);

	/*
	* Now we gathered all boot data, enable regular data
	* collection.
	*/
	if (*boot) {
	*boot = 0;
	goto out;
	}

	wait_event_interruptible(data->read_wait,
	jent_testing_have_data(data));
	if (signal_pending(current)) {
	collected_data = -ERESTARTSYS;
	goto out;
	}

	continue;
	}

	/* We copy out word-wise */
	if (outbuflen < sizeof(u64)) {
	spin_unlock_irqrestore(&data->lock, flags);
	goto out;
	}

	memcpy(outbuf, &data->jent_testing_rb[data->rb_reader],
	sizeof(u64));
	data->rb_reader++;

	spin_unlock_irqrestore(&data->lock, flags);

	outbuf += sizeof(u64);
	outbuflen -= sizeof(u64);
	collected_data += sizeof(u64);
	}

	out:
	jent_testing_fini(data, *boot);
	return collected_data;
	}

	static int jent_testing_extract_user(struct file file, char __user buf,
	size_t nbytes, loff_t *ppos,
	int (reader)(u8 outbuf, u32 outbuflen))
	{
	u8 tmp, tmp_aligned;
	int ret = 0, large_request = (nbytes > 256);

	if (!nbytes)
	return 0;

	/*
	* The intention of this interface is for collecting at least
	* 1000 samples due to the SP800-90B requirements. However, due to
	* memory and performance constraints, it is not desirable to allocate
	* 8000 bytes of memory. Instead, we allocate space for only 125
	* samples, which will allow the user to collect all 1000 samples using
	* 8 calls to this interface.
	*/
	tmp = kmalloc(125 * sizeof(u64) + sizeof(u64), GFP_KERNEL);
	if (!tmp)
	return -ENOMEM;

	tmp_aligned = PTR_ALIGN(tmp, sizeof(u64));

	while (nbytes) {
	int i;

	if (large_request && need_resched()) {
	if (signal_pending(current)) {
	if (ret == 0)
	ret = -ERESTARTSYS;
	break;
	}
	schedule();
	}

	i = min_t(int, nbytes, 125 * sizeof(u64));
	i = reader(tmp_aligned, i);
	if (i <= 0) {
	if (i < 0)
	ret = i;
	break;
	}
	if (copy_to_user(buf, tmp_aligned, i)) {
	ret = -EFAULT;
	break;
	}

	nbytes -= i;
	buf += i;
	ret += i;
	}

	kfree_sensitive(tmp);

	if (ret > 0)
	*ppos += ret;

	return ret;
	}

	/************ Raw High-Resolution Timer Entropy Data Handling ************/

	static u32 boot_raw_hires_test = 0;
	module_param(boot_raw_hires_test, uint, 0644);
	MODULE_PARM_DESC(boot_raw_hires_test,
	"Enable gathering boot time high resolution timer entropy of the first Jitter RNG entropy events");

	static struct jent_testing jent_raw_hires = {
	.rb_reader = 0,
	.rb_writer = ATOMIC_INIT(0),
	.lock = __SPIN_LOCK_UNLOCKED(jent_raw_hires.lock),
	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(jent_raw_hires.read_wait)
	};

	int jent_raw_hires_entropy_store(__u64 value)
	{
	return jent_testing_store(&jent_raw_hires, value, &boot_raw_hires_test);
	}
	EXPORT_SYMBOL(jent_raw_hires_entropy_store);

	static int jent_raw_hires_entropy_reader(u8 *outbuf, u32 outbuflen)
	{
	return jent_testing_reader(&jent_raw_hires, &boot_raw_hires_test,
	outbuf, outbuflen);
	}

	static ssize_t jent_raw_hires_read(struct file file, char __user to,
	size_t count, loff_t *ppos)
	{
	return jent_testing_extract_user(file, to, count, ppos,
	jent_raw_hires_entropy_reader);
	}

	static const struct file_operations jent_raw_hires_fops = {
	.owner = THIS_MODULE,
	.read = jent_raw_hires_read,
	};

	/***************************** Initialization *****************************/

	void jent_testing_init(void)
	{
	jent_raw_debugfs_root = debugfs_create_dir(KBUILD_MODNAME, NULL);

	debugfs_create_file_unsafe("jent_raw_hires", 0400,
	jent_raw_debugfs_root, NULL,
	&jent_raw_hires_fops);
	}
	EXPORT_SYMBOL(jent_testing_init);

	void jent_testing_exit(void)
	{
	debugfs_remove_recursive(jent_raw_debugfs_root);
	}
	EXPORT_SYMBOL(jent_testing_exit);