1 files changed, 137 insertions, 53 deletions

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 84cdf902573..c4419ea1ab0 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -19,7 +19,7 @@
 	Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
 
 	Added generic RNG API
-	Copyright 2006 Michael Buesch <mbuesch@freenet.de>
+	Copyright 2006 Michael Buesch <m@bues.ch>
 	Copyright 2005 (c) MontaVista Software, Inc.
 
 	Please read Documentation/hw_random.txt for details on use.
@@ -37,9 +37,10 @@
 #include <linux/kernel.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
-#include <linux/init.h>
 #include <linux/miscdevice.h>
 #include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/random.h>
 #include <asm/uaccess.h>
 
 
@@ -51,34 +52,52 @@
 static struct hwrng *current_rng;
 static LIST_HEAD(rng_list);
 static DEFINE_MUTEX(rng_mutex);
+static int data_avail;
+static u8 *rng_buffer;
 
+static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
+			       int wait);
 
-static inline int hwrng_init(struct hwrng *rng)
+static size_t rng_buffer_size(void)
 {
-	if (!rng->init)
-		return 0;
-	return rng->init(rng);
+	return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
 }
 
-static inline void hwrng_cleanup(struct hwrng *rng)
+static void add_early_randomness(struct hwrng *rng)
 {
-	if (rng && rng->cleanup)
-		rng->cleanup(rng);
+	unsigned char bytes[16];
+	int bytes_read;
+
+	/*
+	 * Currently only virtio-rng cannot return data during device
+	 * probe, and that's handled in virtio-rng.c itself.  If there
+	 * are more such devices, this call to rng_get_data can be
+	 * made conditional here instead of doing it per-device.
+	 */
+	bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
+	if (bytes_read > 0)
+		add_device_randomness(bytes, bytes_read);
 }
 
-static inline int hwrng_data_present(struct hwrng *rng, int wait)
+static inline int hwrng_init(struct hwrng *rng)
 {
-	if (!rng->data_present)
-		return 1;
-	return rng->data_present(rng, wait);
+	if (rng->init) {
+		int ret;
+
+		ret =  rng->init(rng);
+		if (ret)
+			return ret;
+	}
+	add_early_randomness(rng);
+	return 0;
 }
 
-static inline int hwrng_data_read(struct hwrng *rng, u32 *data)
+static inline void hwrng_cleanup(struct hwrng *rng)
 {
-	return rng->data_read(rng, data);
+	if (rng && rng->cleanup)
+		rng->cleanup(rng);
 }
 
-
 static int rng_dev_open(struct inode *inode, struct file *filp)
 {
 	/* enforce read-only access to this chrdev */
@@ -89,52 +108,90 @@ static int rng_dev_open(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
+			int wait) {
+	int present;
+
+	if (rng->read)
+		return rng->read(rng, (void *)buffer, size, wait);
+
+	if (rng->data_present)
+		present = rng->data_present(rng, wait);
+	else
+		present = 1;
+
+	if (present)
+		return rng->data_read(rng, (u32 *)buffer);
+
+	return 0;
+}
+
 static ssize_t rng_dev_read(struct file *filp, char __user *buf,
 			    size_t size, loff_t *offp)
 {
-	u32 data;
 	ssize_t ret = 0;
 	int err = 0;
-	int bytes_read;
+	int bytes_read, len;
 
 	while (size) {
-		err = -ERESTARTSYS;
-		if (mutex_lock_interruptible(&rng_mutex))
+		if (mutex_lock_interruptible(&rng_mutex)) {
+			err = -ERESTARTSYS;
 			goto out;
+		}
+
 		if (!current_rng) {
-			mutex_unlock(&rng_mutex);
 			err = -ENODEV;
-			goto out;
+			goto out_unlock;
 		}
 
-		bytes_read = 0;
-		if (hwrng_data_present(current_rng,
-				       !(filp->f_flags & O_NONBLOCK)))
-			bytes_read = hwrng_data_read(current_rng, &data);
-		mutex_unlock(&rng_mutex);
+		if (!data_avail) {
+			bytes_read = rng_get_data(current_rng, rng_buffer,
+				rng_buffer_size(),
+				!(filp->f_flags & O_NONBLOCK));
+			if (bytes_read < 0) {
+				err = bytes_read;
+				goto out_unlock;
+			}
+			data_avail = bytes_read;
+		}
 
-		err = -EAGAIN;
-		if (!bytes_read && (filp->f_flags & O_NONBLOCK))
-			goto out;
+		if (!data_avail) {
+			if (filp->f_flags & O_NONBLOCK) {
+				err = -EAGAIN;
+				goto out_unlock;
+			}
+		} else {
+			len = data_avail;
+			if (len > size)
+				len = size;
+
+			data_avail -= len;
 
-		err = -EFAULT;
-		while (bytes_read && size) {
-			if (put_user((u8)data, buf++))
-				goto out;
-			size--;
-			ret++;
-			bytes_read--;
-			data >>= 8;
+			if (copy_to_user(buf + ret, rng_buffer + data_avail,
+								len)) {
+				err = -EFAULT;
+				goto out_unlock;
+			}
+
+			size -= len;
+			ret += len;
 		}
 
+		mutex_unlock(&rng_mutex);
+
 		if (need_resched())
 			schedule_timeout_interruptible(1);
-		err = -ERESTARTSYS;
-		if (signal_pending(current))
+
+		if (signal_pending(current)) {
+			err = -ERESTARTSYS;
 			goto out;
+		}
 	}
 out:
 	return ret ? : err;
+out_unlock:
+	mutex_unlock(&rng_mutex);
+	goto out;
 }
 
 
@@ -142,11 +199,13 @@ static const struct file_operations rng_chrdev_ops = {
 	.owner		= THIS_MODULE,
 	.open		= rng_dev_open,
 	.read		= rng_dev_read,
+	.llseek		= noop_llseek,
 };
 
 static struct miscdevice rng_miscdev = {
 	.minor		= RNG_MISCDEV_MINOR,
 	.name		= RNG_MODULE_NAME,
+	.nodename	= "hwrng",
 	.fops		= &rng_chrdev_ops,
 };
 
@@ -234,11 +293,11 @@ static DEVICE_ATTR(rng_available, S_IRUGO,
 		   NULL);
 
 
-static void unregister_miscdev(bool suspended)
+static void unregister_miscdev(void)
 {
 	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
 	device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
-	__misc_deregister(&rng_miscdev, suspended);
+	misc_deregister(&rng_miscdev);
 }
 
 static int register_miscdev(void)
@@ -268,16 +327,23 @@ err_misc_dereg:
 
 int hwrng_register(struct hwrng *rng)
 {
-	int must_register_misc;
 	int err = -EINVAL;
 	struct hwrng *old_rng, *tmp;
 
 	if (rng->name == NULL ||
-	    rng->data_read == NULL)
+	    (rng->data_read == NULL && rng->read == NULL))
 		goto out;
 
 	mutex_lock(&rng_mutex);
 
+	/* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
+	err = -ENOMEM;
+	if (!rng_buffer) {
+		rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
+		if (!rng_buffer)
+			goto out_unlock;
+	}
+
 	/* Must not register two RNGs with the same name. */
 	err = -EEXIST;
 	list_for_each_entry(tmp, &rng_list, list) {
@@ -285,7 +351,6 @@ int hwrng_register(struct hwrng *rng)
 			goto out_unlock;
 	}
 
-	must_register_misc = (current_rng == NULL);
 	old_rng = current_rng;
 	if (!old_rng) {
 		err = hwrng_init(rng);
@@ -294,18 +359,28 @@ int hwrng_register(struct hwrng *rng)
 		current_rng = rng;
 	}
 	err = 0;
-	if (must_register_misc) {
+	if (!old_rng) {
 		err = register_miscdev();
 		if (err) {
-			if (!old_rng) {
-				hwrng_cleanup(rng);
-				current_rng = NULL;
-			}
+			hwrng_cleanup(rng);
+			current_rng = NULL;
 			goto out_unlock;
 		}
 	}
 	INIT_LIST_HEAD(&rng->list);
 	list_add_tail(&rng->list, &rng_list);
+
+	if (old_rng && !rng->init) {
+		/*
+		 * Use a new device's input to add some randomness to
+		 * the system.  If this rng device isn't going to be
+		 * used right away, its init function hasn't been
+		 * called yet; so only use the randomness from devices
+		 * that don't need an init callback.
+		 */
+		add_early_randomness(rng);
+	}
+
 out_unlock:
 	mutex_unlock(&rng_mutex);
 out:
@@ -313,7 +388,7 @@ out:
 }
 EXPORT_SYMBOL_GPL(hwrng_register);
 
-void __hwrng_unregister(struct hwrng *rng, bool suspended)
+void hwrng_unregister(struct hwrng *rng)
 {
 	int err;
 
@@ -332,12 +407,21 @@ void __hwrng_unregister(struct hwrng *rng, bool suspended)
 		}
 	}
 	if (list_empty(&rng_list))
-		unregister_miscdev(suspended);
+		unregister_miscdev();
 
 	mutex_unlock(&rng_mutex);
 }
-EXPORT_SYMBOL_GPL(__hwrng_unregister);
+EXPORT_SYMBOL_GPL(hwrng_unregister);
+
+static void __exit hwrng_exit(void)
+{
+	mutex_lock(&rng_mutex);
+	BUG_ON(current_rng);
+	kfree(rng_buffer);
+	mutex_unlock(&rng_mutex);
+}
 
+module_exit(hwrng_exit);
 
 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
 MODULE_LICENSE("GPL");