--- /dev/null
+/*
+ * chaoskey - driver for ChaosKey device from Altus Metrum.
+ *
+ * This device provides true random numbers using a noise source based
+ * on a reverse-biased p-n junction in avalanche breakdown. More
+ * details can be found at http://chaoskey.org
+ *
+ * The driver connects to the kernel hardware RNG interface to provide
+ * entropy for /dev/random and other kernel activities. It also offers
+ * a separate /dev/ entry to allow for direct access to the random
+ * bit stream.
+ *
+ * Copyright © 2015 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include <linux/wait.h>
+#include <linux/hw_random.h>
+
+static struct usb_driver chaoskey_driver;
+static struct usb_class_driver chaoskey_class;
+static int chaoskey_rng_read(struct hwrng *rng, void *data,
+ size_t max, bool wait);
+
+#define usb_dbg(usb_if, format, arg...) \
+ dev_dbg(&(usb_if)->dev, format, ## arg)
+
+#define usb_err(usb_if, format, arg...) \
+ dev_err(&(usb_if)->dev, format, ## arg)
+
+/* Version Information */
+#define DRIVER_VERSION "v0.1"
+#define DRIVER_AUTHOR "Keith Packard, keithp@keithp.com"
+#define DRIVER_DESC "Altus Metrum ChaosKey driver"
+#define DRIVER_SHORT "chaoskey"
+
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+#define CHAOSKEY_VENDOR_ID 0x1d50 /* OpenMoko */
+#define CHAOSKEY_PRODUCT_ID 0x60c6 /* ChaosKey */
+
+#define CHAOSKEY_BUF_LEN 64 /* max size of USB full speed packet */
+
+#define NAK_TIMEOUT (HZ) /* stall/wait timeout for device */
+
+#ifdef CONFIG_USB_DYNAMIC_MINORS
+#define USB_CHAOSKEY_MINOR_BASE 0
+#else
+
+/* IOWARRIOR_MINOR_BASE + 16, not official yet */
+#define USB_CHAOSKEY_MINOR_BASE 224
+#endif
+
+static const struct usb_device_id chaoskey_table[] = {
+ { USB_DEVICE(CHAOSKEY_VENDOR_ID, CHAOSKEY_PRODUCT_ID) },
+ { },
+};
+MODULE_DEVICE_TABLE(usb, chaoskey_table);
+
+/* Driver-local specific stuff */
+struct chaoskey {
+ struct usb_interface *interface;
+ char in_ep;
+ struct mutex lock;
+ struct mutex rng_lock;
+ int open; /* open count */
+ int present; /* device not disconnected */
+ int size; /* size of buf */
+ int valid; /* bytes of buf read */
+ int used; /* bytes of buf consumed */
+ char *name; /* product + serial */
+ struct hwrng hwrng; /* Embedded struct for hwrng */
+ int hwrng_registered; /* registered with hwrng API */
+ wait_queue_head_t wait_q; /* for timeouts */
+ char *buf;
+};
+
+static void chaoskey_free(struct chaoskey *dev)
+{
+ usb_dbg(dev->interface, "free");
+ kfree(dev->name);
+ kfree(dev->buf);
+ kfree(dev);
+}
+
+static int chaoskey_probe(struct usb_interface *interface,
+ const struct usb_device_id *id)
+{
+ struct usb_device *udev = interface_to_usbdev(interface);
+ struct usb_host_interface *altsetting = interface->cur_altsetting;
+ int i;
+ int in_ep = -1;
+ struct chaoskey *dev;
+ int result;
+ int size;
+
+ usb_dbg(interface, "probe %s-%s", udev->product, udev->serial);
+
+ /* Find the first bulk IN endpoint and its packet size */
+ for (i = 0; i < altsetting->desc.bNumEndpoints; i++) {
+ if (usb_endpoint_is_bulk_in(&altsetting->endpoint[i].desc)) {
+ in_ep = altsetting->endpoint[i].desc.bEndpointAddress;
+ size = altsetting->endpoint[i].desc.wMaxPacketSize;
+ break;
+ }
+ }
+
+ /* Validate endpoint and size */
+ if (in_ep == -1) {
+ usb_dbg(interface, "no IN endpoint found");
+ return -ENODEV;
+ }
+ if (size <= 0) {
+ usb_dbg(interface, "invalid size (%d)", size);
+ return -ENODEV;
+ }
+
+ if (size > CHAOSKEY_BUF_LEN) {
+ usb_dbg(interface, "size reduced from %d to %d\n",
+ size, CHAOSKEY_BUF_LEN);
+ size = CHAOSKEY_BUF_LEN;
+ }
+
+ /* Looks good, allocate and initialize */
+
+ dev = kzalloc(sizeof(struct chaoskey), GFP_KERNEL);
+
+ if (dev == NULL)
+ return -ENOMEM;
+
+ dev->buf = kmalloc(size, GFP_KERNEL);
+
+ if (dev->buf == NULL) {
+ kfree(dev);
+ return -ENOMEM;
+ }
+
+ /* Construct a name using the product and serial values. Each
+ * device needs a unique name for the hwrng code
+ */
+
+ if (udev->product && udev->serial) {
+ dev->name = kmalloc(strlen(udev->product) + 1 +
+ strlen(udev->serial) + 1, GFP_KERNEL);
+ if (dev->name == NULL) {
+ kfree(dev->buf);
+ kfree(dev);
+ return -ENOMEM;
+ }
+
+ strcpy(dev->name, udev->product);
+ strcat(dev->name, "-");
+ strcat(dev->name, udev->serial);
+ }
+
+ dev->interface = interface;
+
+ dev->in_ep = in_ep;
+
+ dev->size = size;
+ dev->present = 1;
+
+ init_waitqueue_head(&dev->wait_q);
+
+ mutex_init(&dev->lock);
+ mutex_init(&dev->rng_lock);
+
+ usb_set_intfdata(interface, dev);
+
+ result = usb_register_dev(interface, &chaoskey_class);
+ if (result) {
+ usb_err(interface, "Unable to allocate minor number.");
+ usb_set_intfdata(interface, NULL);
+ chaoskey_free(dev);
+ return result;
+ }
+
+ dev->hwrng.name = dev->name ? dev->name : chaoskey_driver.name;
+ dev->hwrng.read = chaoskey_rng_read;
+
+ /* Set the 'quality' metric. Quality is measured in units of
+ * 1/1024's of a bit ("mills"). This should be set to 1024,
+ * but there is a bug in the hwrng core which masks it with
+ * 1023.
+ *
+ * The patch that has been merged to the crypto development
+ * tree for that bug limits the value to 1024 at most, so by
+ * setting this to 1024 + 1023, we get 1023 before the fix is
+ * merged and 1024 afterwards. We'll patch this driver once
+ * both bits of code are in the same tree.
+ */
+ dev->hwrng.quality = 1024 + 1023;
+
+ dev->hwrng_registered = (hwrng_register(&dev->hwrng) == 0);
+ if (!dev->hwrng_registered)
+ usb_err(interface, "Unable to register with hwrng");
+
+ usb_enable_autosuspend(udev);
+
+ usb_dbg(interface, "chaoskey probe success, size %d", dev->size);
+ return 0;
+}
+
+static void chaoskey_disconnect(struct usb_interface *interface)
+{
+ struct chaoskey *dev;
+
+ usb_dbg(interface, "disconnect");
+ dev = usb_get_intfdata(interface);
+ if (!dev) {
+ usb_dbg(interface, "disconnect failed - no dev");
+ return;
+ }
+
+ if (dev->hwrng_registered)
+ hwrng_unregister(&dev->hwrng);
+
+ usb_deregister_dev(interface, &chaoskey_class);
+
+ usb_set_intfdata(interface, NULL);
+ mutex_lock(&dev->lock);
+
+ dev->present = 0;
+
+ if (!dev->open) {
+ mutex_unlock(&dev->lock);
+ chaoskey_free(dev);
+ } else
+ mutex_unlock(&dev->lock);
+
+ usb_dbg(interface, "disconnect done");
+}
+
+static int chaoskey_open(struct inode *inode, struct file *file)
+{
+ struct chaoskey *dev;
+ struct usb_interface *interface;
+
+ /* get the interface from minor number and driver information */
+ interface = usb_find_interface(&chaoskey_driver, iminor(inode));
+ if (!interface)
+ return -ENODEV;
+
+ usb_dbg(interface, "open");
+
+ dev = usb_get_intfdata(interface);
+ if (!dev) {
+ usb_dbg(interface, "open (dev)");
+ return -ENODEV;
+ }
+
+ file->private_data = dev;
+ mutex_lock(&dev->lock);
+ ++dev->open;
+ mutex_unlock(&dev->lock);
+
+ usb_dbg(interface, "open success");
+ return 0;
+}
+
+static int chaoskey_release(struct inode *inode, struct file *file)
+{
+ struct chaoskey *dev = file->private_data;
+ struct usb_interface *interface;
+
+ if (dev == NULL)
+ return -ENODEV;
+
+ interface = dev->interface;
+
+ usb_dbg(interface, "release");
+
+ mutex_lock(&dev->lock);
+
+ usb_dbg(interface, "open count at release is %d", dev->open);
+
+ if (dev->open <= 0) {
+ usb_dbg(interface, "invalid open count (%d)", dev->open);
+ mutex_unlock(&dev->lock);
+ return -ENODEV;
+ }
+
+ --dev->open;
+
+ if (!dev->present) {
+ if (dev->open == 0) {
+ mutex_unlock(&dev->lock);
+ chaoskey_free(dev);
+ } else
+ mutex_unlock(&dev->lock);
+ } else
+ mutex_unlock(&dev->lock);
+
+ usb_dbg(interface, "release success");
+ return 0;
+}
+
+/* Fill the buffer. Called with dev->lock held
+ */
+static int _chaoskey_fill(struct chaoskey *dev)
+{
+ DEFINE_WAIT(wait);
+ int result;
+ int this_read;
+ struct usb_device *udev = interface_to_usbdev(dev->interface);
+
+ usb_dbg(dev->interface, "fill");
+
+ /* Return immediately if someone called before the buffer was
+ * empty */
+ if (dev->valid != dev->used) {
+ usb_dbg(dev->interface, "not empty yet (valid %d used %d)",
+ dev->valid, dev->used);
+ return 0;
+ }
+
+ /* Bail if the device has been removed */
+ if (!dev->present) {
+ usb_dbg(dev->interface, "device not present");
+ return -ENODEV;
+ }
+
+ /* Make sure the device is awake */
+ result = usb_autopm_get_interface(dev->interface);
+ if (result) {
+ usb_dbg(dev->interface, "wakeup failed (result %d)", result);
+ return result;
+ }
+
+ result = usb_bulk_msg(udev,
+ usb_rcvbulkpipe(udev, dev->in_ep),
+ dev->buf, dev->size, &this_read,
+ NAK_TIMEOUT);
+
+ /* Let the device go back to sleep eventually */
+ usb_autopm_put_interface(dev->interface);
+
+ if (result == 0) {
+ dev->valid = this_read;
+ dev->used = 0;
+ }
+
+ usb_dbg(dev->interface, "bulk_msg result %d this_read %d",
+ result, this_read);
+
+ return result;
+}
+
+static ssize_t chaoskey_read(struct file *file,
+ char __user *buffer,
+ size_t count,
+ loff_t *ppos)
+{
+ struct chaoskey *dev;
+ ssize_t read_count = 0;
+ int this_time;
+ int result = 0;
+ unsigned long remain;
+
+ dev = file->private_data;
+
+ if (dev == NULL || !dev->present)
+ return -ENODEV;
+
+ usb_dbg(dev->interface, "read %zu", count);
+
+ while (count > 0) {
+
+ /* Grab the rng_lock briefly to ensure that the hwrng interface
+ * gets priority over other user access
+ */
+ result = mutex_lock_interruptible(&dev->rng_lock);
+ if (result)
+ goto bail;
+ mutex_unlock(&dev->rng_lock);
+
+ result = mutex_lock_interruptible(&dev->lock);
+ if (result)
+ goto bail;
+ if (dev->valid == dev->used) {
+ result = _chaoskey_fill(dev);
+ if (result) {
+ mutex_unlock(&dev->lock);
+ goto bail;
+ }
+
+ /* Read returned zero bytes */
+ if (dev->used == dev->valid) {
+ mutex_unlock(&dev->lock);
+ goto bail;
+ }
+ }
+
+ this_time = dev->valid - dev->used;
+ if (this_time > count)
+ this_time = count;
+
+ remain = copy_to_user(buffer, dev->buf + dev->used, this_time);
+ if (remain) {
+ result = -EFAULT;
+
+ /* Consume the bytes that were copied so we don't leak
+ * data to user space
+ */
+ dev->used += this_time - remain;
+ mutex_unlock(&dev->lock);
+ goto bail;
+ }
+
+ count -= this_time;
+ read_count += this_time;
+ buffer += this_time;
+ dev->used += this_time;
+ mutex_unlock(&dev->lock);
+ }
+bail:
+ if (read_count) {
+ usb_dbg(dev->interface, "read %zu bytes", read_count);
+ return read_count;
+ }
+ usb_dbg(dev->interface, "empty read, result %d", result);
+ return result;
+}
+
+static int chaoskey_rng_read(struct hwrng *rng, void *data,
+ size_t max, bool wait)
+{
+ struct chaoskey *dev = container_of(rng, struct chaoskey, hwrng);
+ int this_time;
+
+ usb_dbg(dev->interface, "rng_read max %zu wait %d", max, wait);
+
+ if (!dev->present) {
+ usb_dbg(dev->interface, "device not present");
+ return 0;
+ }
+
+ /* Hold the rng_lock until we acquire the device lock so that
+ * this operation gets priority over other user access to the
+ * device
+ */
+ mutex_lock(&dev->rng_lock);
+
+ mutex_lock(&dev->lock);
+
+ mutex_unlock(&dev->rng_lock);
+
+ /* Try to fill the buffer if empty. It doesn't actually matter
+ * if _chaoskey_fill works; we'll just return zero bytes as
+ * the buffer will still be empty
+ */
+ if (dev->valid == dev->used)
+ (void) _chaoskey_fill(dev);
+
+ this_time = dev->valid - dev->used;
+ if (this_time > max)
+ this_time = max;
+
+ memcpy(data, dev->buf, this_time);
+
+ dev->used += this_time;
+
+ mutex_unlock(&dev->lock);
+
+ usb_dbg(dev->interface, "rng_read this_time %d\n", this_time);
+ return this_time;
+}
+
+#ifdef CONFIG_PM
+static int chaoskey_suspend(struct usb_interface *interface,
+ pm_message_t message)
+{
+ usb_dbg(interface, "suspend");
+ return 0;
+}
+
+static int chaoskey_resume(struct usb_interface *interface)
+{
+ usb_dbg(interface, "resume");
+ return 0;
+}
+#else
+#define chaoskey_suspend NULL
+#define chaoskey_resume NULL
+#endif
+
+/* file operation pointers */
+static const struct file_operations chaoskey_fops = {
+ .owner = THIS_MODULE,
+ .read = chaoskey_read,
+ .open = chaoskey_open,
+ .release = chaoskey_release,
+ .llseek = default_llseek,
+};
+
+/* class driver information */
+static struct usb_class_driver chaoskey_class = {
+ .name = "chaoskey%d",
+ .fops = &chaoskey_fops,
+ .minor_base = USB_CHAOSKEY_MINOR_BASE,
+};
+
+/* usb specific object needed to register this driver with the usb subsystem */
+static struct usb_driver chaoskey_driver = {
+ .name = DRIVER_SHORT,
+ .probe = chaoskey_probe,
+ .disconnect = chaoskey_disconnect,
+ .suspend = chaoskey_suspend,
+ .resume = chaoskey_resume,
+ .reset_resume = chaoskey_resume,
+ .id_table = chaoskey_table,
+ .supports_autosuspend = 1,
+};
+
+module_usb_driver(chaoskey_driver);
+
projects / karo-tx-linux.git / commitdiff