1 files changed, 369 insertions, 0 deletions
diff --git a/drivers/char/raw.c b/drivers/char/raw.c
new file mode 100644
index 000000000..fd6eec808
--- /dev/null
+++ b/drivers/char/raw.c
@@ -0,0 +1,369 @@
+/*
+ * linux/drivers/char/raw.c
+ *
+ * Front-end raw character devices.  These can be bound to any block
+ * devices to provide genuine Unix raw character device semantics.
+ *
+ * We reserve minor number 0 for a control interface.  ioctl()s on this
+ * device are used to bind the other minor numbers to block devices.
+ */
+
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/major.h>
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/module.h>
+#include <linux/raw.h>
+#include <linux/capability.h>
+#include <linux/uio.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/gfp.h>
+#include <linux/compat.h>
+#include <linux/vmalloc.h>
+
+#include <linux/uaccess.h>
+
+struct raw_device_data {
+	struct block_device *binding;
+	int inuse;
+};
+
+static struct class *raw_class;
+static struct raw_device_data *raw_devices;
+static DEFINE_MUTEX(raw_mutex);
+static const struct file_operations raw_ctl_fops; /* forward declaration */
+
+static int max_raw_minors = MAX_RAW_MINORS;
+
+module_param(max_raw_minors, int, 0);
+MODULE_PARM_DESC(max_raw_minors, "Maximum number of raw devices (1-65536)");
+
+/*
+ * Open/close code for raw IO.
+ *
+ * We just rewrite the i_mapping for the /dev/raw/rawN file descriptor to
+ * point at the blockdev's address_space and set the file handle to use
+ * O_DIRECT.
+ *
+ * Set the device's soft blocksize to the minimum possible.  This gives the
+ * finest possible alignment and has no adverse impact on performance.
+ */
+static int raw_open(struct inode *inode, struct file *filp)
+{
+	const int minor = iminor(inode);
+	struct block_device *bdev;
+	int err;
+
+	if (minor == 0) {	/* It is the control device */
+		filp->f_op = &raw_ctl_fops;
+		return 0;
+	}
+
+	mutex_lock(&raw_mutex);
+
+	/*
+	 * All we need to do on open is check that the device is bound.
+	 */
+	bdev = raw_devices[minor].binding;
+	err = -ENODEV;
+	if (!bdev)
+		goto out;
+	bdgrab(bdev);
+	err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open);
+	if (err)
+		goto out;
+	err = set_blocksize(bdev, bdev_logical_block_size(bdev));
+	if (err)
+		goto out1;
+	filp->f_flags |= O_DIRECT;
+	filp->f_mapping = bdev->bd_inode->i_mapping;
+	if (++raw_devices[minor].inuse == 1)
+		file_inode(filp)->i_mapping =
+			bdev->bd_inode->i_mapping;
+	filp->private_data = bdev;
+	mutex_unlock(&raw_mutex);
+	return 0;
+
+out1:
+	blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
+out:
+	mutex_unlock(&raw_mutex);
+	return err;
+}
+
+/*
+ * When the final fd which refers to this character-special node is closed, we
+ * make its ->mapping point back at its own i_data.
+ */
+static int raw_release(struct inode *inode, struct file *filp)
+{
+	const int minor= iminor(inode);
+	struct block_device *bdev;
+
+	mutex_lock(&raw_mutex);
+	bdev = raw_devices[minor].binding;
+	if (--raw_devices[minor].inuse == 0)
+		/* Here  inode->i_mapping == bdev->bd_inode->i_mapping  */
+		inode->i_mapping = &inode->i_data;
+	mutex_unlock(&raw_mutex);
+
+	blkdev_put(bdev, filp->f_mode | FMODE_EXCL);
+	return 0;
+}
+
+/*
+ * Forward ioctls to the underlying block device.
+ */
+static long
+raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
+{
+	struct block_device *bdev = filp->private_data;
+	return blkdev_ioctl(bdev, 0, command, arg);
+}
+
+static int bind_set(int number, u64 major, u64 minor)
+{
+	dev_t dev = MKDEV(major, minor);
+	struct raw_device_data *rawdev;
+	int err = 0;
+
+	if (number <= 0 || number >= max_raw_minors)
+		return -EINVAL;
+
+	if (MAJOR(dev) != major || MINOR(dev) != minor)
+		return -EINVAL;
+
+	rawdev = &raw_devices[number];
+
+	/*
+	 * This is like making block devices, so demand the
+	 * same capability
+	 */
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	/*
+	 * For now, we don't need to check that the underlying
+	 * block device is present or not: we can do that when
+	 * the raw device is opened.  Just check that the
+	 * major/minor numbers make sense.
+	 */
+
+	if (MAJOR(dev) == 0 && dev != 0)
+		return -EINVAL;
+
+	mutex_lock(&raw_mutex);
+	if (rawdev->inuse) {
+		mutex_unlock(&raw_mutex);
+		return -EBUSY;
+	}
+	if (rawdev->binding) {
+		bdput(rawdev->binding);
+		module_put(THIS_MODULE);
+	}
+	if (!dev) {
+		/* unbind */
+		rawdev->binding = NULL;
+		device_destroy(raw_class, MKDEV(RAW_MAJOR, number));
+	} else {
+		rawdev->binding = bdget(dev);
+		if (rawdev->binding == NULL) {
+			err = -ENOMEM;
+		} else {
+			dev_t raw = MKDEV(RAW_MAJOR, number);
+			__module_get(THIS_MODULE);
+			device_destroy(raw_class, raw);
+			device_create(raw_class, NULL, raw, NULL,
+				      "raw%d", number);
+		}
+	}
+	mutex_unlock(&raw_mutex);
+	return err;
+}
+
+static int bind_get(int number, dev_t *dev)
+{
+	struct raw_device_data *rawdev;
+	struct block_device *bdev;
+
+	if (number <= 0 || number >= max_raw_minors)
+		return -EINVAL;
+
+	rawdev = &raw_devices[number];
+
+	mutex_lock(&raw_mutex);
+	bdev = rawdev->binding;
+	*dev = bdev ? bdev->bd_dev : 0;
+	mutex_unlock(&raw_mutex);
+	return 0;
+}
+
+/*
+ * Deal with ioctls against the raw-device control interface, to bind
+ * and unbind other raw devices.
+ */
+static long raw_ctl_ioctl(struct file *filp, unsigned int command,
+			  unsigned long arg)
+{
+	struct raw_config_request rq;
+	dev_t dev;
+	int err;
+
+	switch (command) {
+	case RAW_SETBIND:
+		if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
+			return -EFAULT;
+
+		return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
+
+	case RAW_GETBIND:
+		if (copy_from_user(&rq, (void __user *) arg, sizeof(rq)))
+			return -EFAULT;
+
+		err = bind_get(rq.raw_minor, &dev);
+		if (err)
+			return err;
+
+		rq.block_major = MAJOR(dev);
+		rq.block_minor = MINOR(dev);
+
+		if (copy_to_user((void __user *)arg, &rq, sizeof(rq)))
+			return -EFAULT;
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+#ifdef CONFIG_COMPAT
+struct raw32_config_request {
+	compat_int_t	raw_minor;
+	compat_u64	block_major;
+	compat_u64	block_minor;
+};
+
+static long raw_ctl_compat_ioctl(struct file *file, unsigned int cmd,
+				unsigned long arg)
+{
+	struct raw32_config_request __user *user_req = compat_ptr(arg);
+	struct raw32_config_request rq;
+	dev_t dev;
+	int err = 0;
+
+	switch (cmd) {
+	case RAW_SETBIND:
+		if (copy_from_user(&rq, user_req, sizeof(rq)))
+			return -EFAULT;
+
+		return bind_set(rq.raw_minor, rq.block_major, rq.block_minor);
+
+	case RAW_GETBIND:
+		if (copy_from_user(&rq, user_req, sizeof(rq)))
+			return -EFAULT;
+
+		err = bind_get(rq.raw_minor, &dev);
+		if (err)
+			return err;
+
+		rq.block_major = MAJOR(dev);
+		rq.block_minor = MINOR(dev);
+
+		if (copy_to_user(user_req, &rq, sizeof(rq)))
+			return -EFAULT;
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+#endif
+
+static const struct file_operations raw_fops = {
+	.read_iter	= blkdev_read_iter,
+	.write_iter	= blkdev_write_iter,
+	.fsync		= blkdev_fsync,
+	.open		= raw_open,
+	.release	= raw_release,
+	.unlocked_ioctl = raw_ioctl,
+	.llseek		= default_llseek,
+	.owner		= THIS_MODULE,
+};
+
+static const struct file_operations raw_ctl_fops = {
+	.unlocked_ioctl = raw_ctl_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= raw_ctl_compat_ioctl,
+#endif
+	.open		= raw_open,
+	.owner		= THIS_MODULE,
+	.llseek		= noop_llseek,
+};
+
+static struct cdev raw_cdev;
+
+static char *raw_devnode(struct device *dev, umode_t *mode)
+{
+	return kasprintf(GFP_KERNEL, "raw/%s", dev_name(dev));
+}
+
+static int __init raw_init(void)
+{
+	dev_t dev = MKDEV(RAW_MAJOR, 0);
+	int ret;
+
+	if (max_raw_minors < 1 || max_raw_minors > 65536) {
+		printk(KERN_WARNING "raw: invalid max_raw_minors (must be"
+			" between 1 and 65536), using %d\n", MAX_RAW_MINORS);
+		max_raw_minors = MAX_RAW_MINORS;
+	}
+
+	raw_devices = vzalloc(array_size(max_raw_minors,
+					 sizeof(struct raw_device_data)));
+	if (!raw_devices) {
+		printk(KERN_ERR "Not enough memory for raw device structures\n");
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	ret = register_chrdev_region(dev, max_raw_minors, "raw");
+	if (ret)
+		goto error;
+
+	cdev_init(&raw_cdev, &raw_fops);
+	ret = cdev_add(&raw_cdev, dev, max_raw_minors);
+	if (ret)
+		goto error_region;
+	raw_class = class_create(THIS_MODULE, "raw");
+	if (IS_ERR(raw_class)) {
+		printk(KERN_ERR "Error creating raw class.\n");
+		cdev_del(&raw_cdev);
+		ret = PTR_ERR(raw_class);
+		goto error_region;
+	}
+	raw_class->devnode = raw_devnode;
+	device_create(raw_class, NULL, MKDEV(RAW_MAJOR, 0), NULL, "rawctl");
+
+	return 0;
+
+error_region:
+	unregister_chrdev_region(dev, max_raw_minors);
+error:
+	vfree(raw_devices);
+	return ret;
+}
+
+static void __exit raw_exit(void)
+{
+	device_destroy(raw_class, MKDEV(RAW_MAJOR, 0));
+	class_destroy(raw_class);
+	cdev_del(&raw_cdev);
+	unregister_chrdev_region(MKDEV(RAW_MAJOR, 0), max_raw_minors);
+}
+
+module_init(raw_init);
+module_exit(raw_exit);
+MODULE_LICENSE("GPL");