--- /dev/null
+/*
+ * 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/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 <asm/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;
+ igrab(bdev->bd_inode);
+ 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(sizeof(struct raw_device_data) * max_raw_minors);
+ 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");
Code Review / kvmfornfv.git / blobdiff