// SPDX-License-Identifier: GPL-2.0-only/* * HID raw devices, giving access to raw HID events. * * In comparison to hiddev, this device does not process the * hid events at all (no parsing, no lookups). This lets applications * to work on raw hid events as they want to, and avoids a need to * use a transport-specific userspace libhid/libusb libraries. * * Copyright (c) 2007-2014 Jiri Kosina */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/fs.h>#include <linux/module.h>#include <linux/errno.h>#include <linux/kernel.h>#include <linux/init.h>#include <linux/cdev.h>#include <linux/poll.h>#include <linux/device.h>#include <linux/major.h>#include <linux/slab.h>#include <linux/hid.h>#include <linux/mutex.h>#include <linux/sched/signal.h>#include <linux/string.h> #include <linux/hidraw.h> static int hidraw_major;static struct cdev hidraw_cdev;static const struct class hidraw_class = { .name = "hidraw",};static struct hidraw *hidraw_table[HIDRAW_MAX_DEVICES];static DECLARE_RWSEM(minors_rwsem); static inline bool hidraw_is_revoked(struct hidraw_list *list){ return list->revoked;} static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos){ struct hidraw_list *list = file->private_data; int ret = 0, len; DECLARE_WAITQUEUE(wait, current); if (hidraw_is_revoked(list)) return -ENODEV; mutex_lock(&list->read_mutex); while (ret == 0) { if (list->head == list->tail) { add_wait_queue(&list->hidraw->wait, &wait); set_current_state(TASK_INTERRUPTIBLE); while (list->head == list->tail) { if (signal_pending(current)) { ret = -ERESTARTSYS; break; } if (!list->hidraw->exist) { ret = -EIO; break; } if (file->f_flags & O_NONBLOCK) { ret = -EAGAIN; break; } /* allow O_NONBLOCK to work well from other threads */ mutex_unlock(&list->read_mutex); schedule(); mutex_lock(&list->read_mutex); set_current_state(TASK_INTERRUPTIBLE); } set_current_state(TASK_RUNNING); remove_wait_queue(&list->hidraw->wait, &wait); } if (ret) goto out; len = list->buffer[list->tail].len > count ? count : list->buffer[list->tail].len; if (list->buffer[list->tail].value) { if (copy_to_user(buffer, list->buffer[list->tail].value, len)) { ret = -EFAULT; goto out; } ret = len; } kfree(list->buffer[list->tail].value); list->buffer[list->tail].value = NULL; list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1); }out: mutex_unlock(&list->read_mutex); return ret;} /* * The first byte of the report buffer is expected to be a report number. */static ssize_t hidraw_send_report(struct file *file, const char __user *buffer, size_t count, unsigned char report_type){ unsigned int minor = iminor(file_inode(file)); struct hid_device *dev; __u8 *buf; int ret = 0; lockdep_assert_held(&minors_rwsem); if (!hidraw_table[minor] || !hidraw_table[minor]->exist) { ret = -ENODEV; goto out; } dev = hidraw_table[minor]->hid; if (count > HID_MAX_BUFFER_SIZE) { hid_warn(dev, "pid %d passed too large report\n", task_pid_nr(current)); ret = -EINVAL; goto out; } if (count < 2) { hid_warn(dev, "pid %d passed too short report\n", task_pid_nr(current)); ret = -EINVAL; goto out; } buf = memdup_user(buffer, count); if (IS_ERR(buf)) { ret = PTR_ERR(buf); goto out; } if ((report_type == HID_OUTPUT_REPORT) && !(dev->quirks & HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP)) { ret = __hid_hw_output_report(dev, buf, count, (u64)(long)file, false); /* * compatibility with old implementation of USB-HID and I2C-HID: * if the device does not support receiving output reports, * on an interrupt endpoint, fallback to SET_REPORT HID command. */ if (ret != -ENOSYS) goto out_free; } ret = __hid_hw_raw_request(dev, buf[0], buf, count, report_type, HID_REQ_SET_REPORT, (u64)(long)file, false); out_free: kfree(buf);out: return ret;} static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos){ struct hidraw_list *list = file->private_data; ssize_t ret; down_read(&minors_rwsem); if (hidraw_is_revoked(list)) ret = -ENODEV; else ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT); up_read(&minors_rwsem); return ret;} /* * This function performs a Get_Report transfer over the control endpoint * per section 7.2.1 of the HID specification, version 1.1. The first byte * of buffer is the report number to request, or 0x0 if the device does not * use numbered reports. The report_type parameter can be HID_FEATURE_REPORT * or HID_INPUT_REPORT. */static ssize_t hidraw_get_report(struct file *file, char __user *buffer, size_t count, unsigned char report_type){ unsigned int minor = iminor(file_inode(file)); struct hid_device *dev; __u8 *buf; int ret = 0, len; unsigned char report_number; lockdep_assert_held(&minors_rwsem); if (!hidraw_table[minor] || !hidraw_table[minor]->exist) { ret = -ENODEV; goto out; } dev = hidraw_table[minor]->hid; if (!dev->ll_driver->raw_request) { ret = -ENODEV; goto out; } if (count > HID_MAX_BUFFER_SIZE) { hid_warn(dev, "pid %d passed too large report\n", task_pid_nr(current)); ret = -EINVAL; goto out; } if (count < 2) { hid_warn(dev, "pid %d passed too short report\n", task_pid_nr(current)); ret = -EINVAL; goto out; } buf = kmalloc(count, GFP_KERNEL); if (!buf) { ret = -ENOMEM; goto out; } /* * Read the first byte from the user. This is the report number, * which is passed to hid_hw_raw_request(). */ if (copy_from_user(&report_number, buffer, 1)) { ret = -EFAULT; goto out_free; } ret = __hid_hw_raw_request(dev, report_number, buf, count, report_type, HID_REQ_GET_REPORT, (u64)(long)file, false); if (ret < 0) goto out_free; len = (ret < count) ? ret : count; if (copy_to_user(buffer, buf, len)) { ret = -EFAULT; goto out_free; } ret = len; out_free: kfree(buf);out: return ret;} static __poll_t hidraw_poll(struct file *file, poll_table *wait){ struct hidraw_list *list = file->private_data; __poll_t mask = EPOLLOUT | EPOLLWRNORM; /* hidraw is always writable */ poll_wait(file, &list->hidraw->wait, wait); if (list->head != list->tail) mask |= EPOLLIN | EPOLLRDNORM; if (!list->hidraw->exist || hidraw_is_revoked(list)) mask |= EPOLLERR | EPOLLHUP; return mask;} static int hidraw_open(struct inode *inode, struct file *file){ unsigned int minor = iminor(inode); struct hidraw *dev; struct hidraw_list *list; unsigned long flags; int err = 0; if (!(list = kzalloc_obj(struct hidraw_list))) { err = -ENOMEM; goto out; } /* * Technically not writing to the hidraw_table but a write lock is * required to protect the device refcount. This is symmetrical to * hidraw_release(). */ down_write(&minors_rwsem); if (!hidraw_table[minor] || !hidraw_table[minor]->exist) { err = -ENODEV; goto out_unlock; } dev = hidraw_table[minor]; if (!dev->open++) { err = hid_hw_power(dev->hid, PM_HINT_FULLON); if (err < 0) { dev->open--; goto out_unlock; } err = hid_hw_open(dev->hid); if (err < 0) { hid_hw_power(dev->hid, PM_HINT_NORMAL); dev->open--; goto out_unlock; } } list->hidraw = hidraw_table[minor]; mutex_init(&list->read_mutex); spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags); list_add_tail(&list->node, &hidraw_table[minor]->list); spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags); file->private_data = list;out_unlock: up_write(&minors_rwsem);out: if (err < 0) kfree(list); return err; } static int hidraw_fasync(int fd, struct file *file, int on){ struct hidraw_list *list = file->private_data; if (hidraw_is_revoked(list)) return -ENODEV; return fasync_helper(fd, file, on, &list->fasync);} static void drop_ref(struct hidraw *hidraw, int exists_bit){ if (exists_bit) { hidraw->exist = 0; if (hidraw->open) { hid_hw_close(hidraw->hid); wake_up_interruptible(&hidraw->wait); } device_destroy(&hidraw_class, MKDEV(hidraw_major, hidraw->minor)); } else { --hidraw->open; } if (!hidraw->open) { if (!hidraw->exist) { hidraw_table[hidraw->minor] = NULL; kfree(hidraw); } else { /* close device for last reader */ hid_hw_close(hidraw->hid); hid_hw_power(hidraw->hid, PM_HINT_NORMAL); } }} static int hidraw_release(struct inode * inode, struct file * file){ unsigned int minor = iminor(inode); struct hidraw_list *list = file->private_data; unsigned long flags; down_write(&minors_rwsem); spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags); while (list->tail != list->head) { kfree(list->buffer[list->tail].value); list->buffer[list->tail].value = NULL; list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1); } list_del(&list->node); spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags); kfree(list); drop_ref(hidraw_table[minor], 0); up_write(&minors_rwsem); return 0;} static int hidraw_revoke(struct hidraw_list *list){ list->revoked = true; return 0;} static long hidraw_fixed_size_ioctl(struct file *file, struct hidraw *dev, unsigned int cmd, void __user *arg){ struct hid_device *hid = dev->hid; switch (cmd) { case HIDIOCGRDESCSIZE: if (put_user(hid->rsize, (int __user *)arg)) return -EFAULT; break; case HIDIOCGRDESC: { __u32 len; if (get_user(len, (int __user *)arg)) return -EFAULT; if (len > HID_MAX_DESCRIPTOR_SIZE - 1) return -EINVAL; if (copy_to_user(arg + offsetof( struct hidraw_report_descriptor, value[0]), hid->rdesc, min(hid->rsize, len))) return -EFAULT; break; } case HIDIOCGRAWINFO: { struct hidraw_devinfo dinfo; dinfo.bustype = hid->bus; dinfo.vendor = hid->vendor; dinfo.product = hid->product; if (copy_to_user(arg, &dinfo, sizeof(dinfo))) return -EFAULT; break; } case HIDIOCREVOKE: { struct hidraw_list *list = file->private_data; if (arg) return -EINVAL; return hidraw_revoke(list); } default: /* * None of the above ioctls can return -EAGAIN, so * use it as a marker that we need to check variable * length ioctls. */ return -EAGAIN; } return 0;} static long hidraw_rw_variable_size_ioctl(struct file *file, struct hidraw *dev, unsigned int cmd, void __user *user_arg){ int len = _IOC_SIZE(cmd); switch (cmd & ~IOCSIZE_MASK) { case HIDIOCSFEATURE(0): return hidraw_send_report(file, user_arg, len, HID_FEATURE_REPORT); case HIDIOCGFEATURE(0): return hidraw_get_report(file, user_arg, len, HID_FEATURE_REPORT); case HIDIOCSINPUT(0): return hidraw_send_report(file, user_arg, len, HID_INPUT_REPORT); case HIDIOCGINPUT(0): return hidraw_get_report(file, user_arg, len, HID_INPUT_REPORT); case HIDIOCSOUTPUT(0): return hidraw_send_report(file, user_arg, len, HID_OUTPUT_REPORT); case HIDIOCGOUTPUT(0): return hidraw_get_report(file, user_arg, len, HID_OUTPUT_REPORT); } return -EINVAL;} static long hidraw_ro_variable_size_ioctl(struct file *file, struct hidraw *dev, unsigned int cmd, void __user *user_arg){ struct hid_device *hid = dev->hid; int len = _IOC_SIZE(cmd); int field_len; switch (cmd & ~IOCSIZE_MASK) { case HIDIOCGRAWNAME(0): field_len = strlen(hid->name) + 1; if (len > field_len) len = field_len; return copy_to_user(user_arg, hid->name, len) ? -EFAULT : len; case HIDIOCGRAWPHYS(0): field_len = strlen(hid->phys) + 1; if (len > field_len) len = field_len; return copy_to_user(user_arg, hid->phys, len) ? -EFAULT : len; case HIDIOCGRAWUNIQ(0):Lines 1–500 of 710. 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// SPDX-License-Identifier: GPL-2.0-only /* * HID raw devices, giving access to raw HID events. * * In comparison to hiddev, this device does not process the * hid events at all (no parsing, no lookups). This lets applications * to work on raw hid events as they want to, and avoids a need to * use a transport-specific userspace libhid/libusb libraries. * * Copyright (c) 2007-2014 Jiri Kosina */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/fs.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/cdev.h> #include <linux/poll.h> #include <linux/device.h> #include <linux/major.h> #include <linux/slab.h> #include <linux/hid.h> #include <linux/mutex.h> #include <linux/sched/signal.h> #include <linux/string.h> #include <linux/hidraw.h> static int hidraw_major; static struct cdev hidraw_cdev; static const struct class hidraw_class = { .name = "hidraw", }; static struct hidraw *hidraw_table[HIDRAW_MAX_DEVICES]; static DECLARE_RWSEM(minors_rwsem); static inline bool hidraw_is_revoked(struct hidraw_list *list) { return list->revoked; } static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) { struct hidraw_list *list = file->private_data; int ret = 0, len; DECLARE_WAITQUEUE(wait, current); if (hidraw_is_revoked(list)) return -ENODEV; mutex_lock(&list->read_mutex); while (ret == 0) { if (list->head == list->tail) { add_wait_queue(&list->hidraw->wait, &wait); set_current_state(TASK_INTERRUPTIBLE); while (list->head == list->tail) { if (signal_pending(current)) { ret = -ERESTARTSYS; break; } if (!list->hidraw->exist) { ret = -EIO; break; } if (file->f_flags & O_NONBLOCK) { ret = -EAGAIN; break; } /* allow O_NONBLOCK to work well from other threads */ mutex_unlock(&list->read_mutex); schedule(); mutex_lock(&list->read_mutex); set_current_state(TASK_INTERRUPTIBLE); } set_current_state(TASK_RUNNING); remove_wait_queue(&list->hidraw->wait, &wait); } if (ret) goto out; len = list->buffer[list->tail].len > count ? count : list->buffer[list->tail].len; if (list->buffer[list->tail].value) { if (copy_to_user(buffer, list->buffer[list->tail].value, len)) { ret = -EFAULT; goto out; } ret = len; } kfree(list->buffer[list->tail].value); list->buffer[list->tail].value = NULL; list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1); } out: mutex_unlock(&list->read_mutex); return ret; } /* * The first byte of the report buffer is expected to be a report number. */ static ssize_t hidraw_send_report(struct file *file, const char __user *buffer, size_t count, unsigned char report_type) { unsigned int minor = iminor(file_inode(file)); struct hid_device *dev; __u8 *buf; int ret = 0; lockdep_assert_held(&minors_rwsem); if (!hidraw_table[minor] || !hidraw_table[minor]->exist) { ret = -ENODEV; goto out; } dev = hidraw_table[minor]->hid; if (count > HID_MAX_BUFFER_SIZE) { hid_warn(dev, "pid %d passed too large report\n", task_pid_nr(current)); ret = -EINVAL; goto out; } if (count < 2) { hid_warn(dev, "pid %d passed too short report\n", task_pid_nr(current)); ret = -EINVAL; goto out; } buf = memdup_user(buffer, count); if (IS_ERR(buf)) { ret = PTR_ERR(buf); goto out; } if ((report_type == HID_OUTPUT_REPORT) && !(dev->quirks & HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP)) { ret = __hid_hw_output_report(dev, buf, count, (u64)(long)file, false); /* * compatibility with old implementation of USB-HID and I2C-HID: * if the device does not support receiving output reports, * on an interrupt endpoint, fallback to SET_REPORT HID command. */ if (ret != -ENOSYS) goto out_free; } ret = __hid_hw_raw_request(dev, buf[0], buf, count, report_type, HID_REQ_SET_REPORT, (u64)(long)file, false); out_free: kfree(buf); out: return ret; } static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos) { struct hidraw_list *list = file->private_data; ssize_t ret; down_read(&minors_rwsem); if (hidraw_is_revoked(list)) ret = -ENODEV; else ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT); up_read(&minors_rwsem); return ret; } /* * This function performs a Get_Report transfer over the control endpoint * per section 7.2.1 of the HID specification, version 1.1. The first byte * of buffer is the report number to request, or 0x0 if the device does not * use numbered reports. The report_type parameter can be HID_FEATURE_REPORT * or HID_INPUT_REPORT. */ static ssize_t hidraw_get_report(struct file *file, char __user *buffer, size_t count, unsigned char report_type) { unsigned int minor = iminor(file_inode(file)); struct hid_device *dev; __u8 *buf; int ret = 0, len; unsigned char report_number; lockdep_assert_held(&minors_rwsem); if (!hidraw_table[minor] || !hidraw_table[minor]->exist) { ret = -ENODEV; goto out; } dev = hidraw_table[minor]->hid; if (!dev->ll_driver->raw_request) { ret = -ENODEV; goto out; } if (count > HID_MAX_BUFFER_SIZE) { hid_warn(dev, "pid %d passed too large report\n", task_pid_nr(current)); ret = -EINVAL; goto out; } if (count < 2) { hid_warn(dev, "pid %d passed too short report\n", task_pid_nr(current)); ret = -EINVAL; goto out; } buf = kmalloc(count, GFP_KERNEL); if (!buf) { ret = -ENOMEM; goto out; } /* * Read the first byte from the user. This is the report number, * which is passed to hid_hw_raw_request(). */ if (copy_from_user(&report_number, buffer, 1)) { ret = -EFAULT; goto out_free; } ret = __hid_hw_raw_request(dev, report_number, buf, count, report_type, HID_REQ_GET_REPORT, (u64)(long)file, false); if (ret < 0) goto out_free; len = (ret < count) ? ret : count; if (copy_to_user(buffer, buf, len)) { ret = -EFAULT; goto out_free; } ret = len; out_free: kfree(buf); out: return ret; } static __poll_t hidraw_poll(struct file *file, poll_table *wait) { struct hidraw_list *list = file->private_data; __poll_t mask = EPOLLOUT | EPOLLWRNORM; /* hidraw is always writable */ poll_wait(file, &list->hidraw->wait, wait); if (list->head != list->tail) mask |= EPOLLIN | EPOLLRDNORM; if (!list->hidraw->exist || hidraw_is_revoked(list)) mask |= EPOLLERR | EPOLLHUP; return mask; } static int hidraw_open(struct inode *inode, struct file *file) { unsigned int minor = iminor(inode); struct hidraw *dev; struct hidraw_list *list; unsigned long flags; int err = 0; if (!(list = kzalloc_obj(struct hidraw_list))) { err = -ENOMEM; goto out; } /* * Technically not writing to the hidraw_table but a write lock is * required to protect the device refcount. This is symmetrical to * hidraw_release(). */ down_write(&minors_rwsem); if (!hidraw_table[minor] || !hidraw_table[minor]->exist) { err = -ENODEV; goto out_unlock; } dev = hidraw_table[minor]; if (!dev->open++) { err = hid_hw_power(dev->hid, PM_HINT_FULLON); if (err < 0) { dev->open--; goto out_unlock; } err = hid_hw_open(dev->hid); if (err < 0) { hid_hw_power(dev->hid, PM_HINT_NORMAL); dev->open--; goto out_unlock; } } list->hidraw = hidraw_table[minor]; mutex_init(&list->read_mutex); spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags); list_add_tail(&list->node, &hidraw_table[minor]->list); spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags); file->private_data = list; out_unlock: up_write(&minors_rwsem); out: if (err < 0) kfree(list); return err; } static int hidraw_fasync(int fd, struct file *file, int on) { struct hidraw_list *list = file->private_data; if (hidraw_is_revoked(list)) return -ENODEV; return fasync_helper(fd, file, on, &list->fasync); } static void drop_ref(struct hidraw *hidraw, int exists_bit) { if (exists_bit) { hidraw->exist = 0; if (hidraw->open) { hid_hw_close(hidraw->hid); wake_up_interruptible(&hidraw->wait); } device_destroy(&hidraw_class, MKDEV(hidraw_major, hidraw->minor)); } else { --hidraw->open; } if (!hidraw->open) { if (!hidraw->exist) { hidraw_table[hidraw->minor] = NULL; kfree(hidraw); } else { /* close device for last reader */ hid_hw_close(hidraw->hid); hid_hw_power(hidraw->hid, PM_HINT_NORMAL); } } } static int hidraw_release(struct inode * inode, struct file * file) { unsigned int minor = iminor(inode); struct hidraw_list *list = file->private_data; unsigned long flags; down_write(&minors_rwsem); spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags); while (list->tail != list->head) { kfree(list->buffer[list->tail].value); list->buffer[list->tail].value = NULL; list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1); } list_del(&list->node); spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags); kfree(list); drop_ref(hidraw_table[minor], 0); up_write(&minors_rwsem); return 0; } static int hidraw_revoke(struct hidraw_list *list) { list->revoked = true; return 0; } static long hidraw_fixed_size_ioctl(struct file *file, struct hidraw *dev, unsigned int cmd, void __user *arg) { struct hid_device *hid = dev->hid; switch (cmd) { case HIDIOCGRDESCSIZE: if (put_user(hid->rsize, (int __user *)arg)) return -EFAULT; break; case HIDIOCGRDESC: { __u32 len; if (get_user(len, (int __user *)arg)) return -EFAULT; if (len > HID_MAX_DESCRIPTOR_SIZE - 1) return -EINVAL; if (copy_to_user(arg + offsetof( struct hidraw_report_descriptor, value[0]), hid->rdesc, min(hid->rsize, len))) return -EFAULT; break; } case HIDIOCGRAWINFO: { struct hidraw_devinfo dinfo; dinfo.bustype = hid->bus; dinfo.vendor = hid->vendor; dinfo.product = hid->product; if (copy_to_user(arg, &dinfo, sizeof(dinfo))) return -EFAULT; break; } case HIDIOCREVOKE: { struct hidraw_list *list = file->private_data; if (arg) return -EINVAL; return hidraw_revoke(list); } default: /* * None of the above ioctls can return -EAGAIN, so * use it as a marker that we need to check variable * length ioctls. */ return -EAGAIN; } return 0; } static long hidraw_rw_variable_size_ioctl(struct file *file, struct hidraw *dev, unsigned int cmd, void __user *user_arg) { int len = _IOC_SIZE(cmd); switch (cmd & ~IOCSIZE_MASK) { case HIDIOCSFEATURE(0): return hidraw_send_report(file, user_arg, len, HID_FEATURE_REPORT); case HIDIOCGFEATURE(0): return hidraw_get_report(file, user_arg, len, HID_FEATURE_REPORT); case HIDIOCSINPUT(0): return hidraw_send_report(file, user_arg, len, HID_INPUT_REPORT); case HIDIOCGINPUT(0): return hidraw_get_report(file, user_arg, len, HID_INPUT_REPORT); case HIDIOCSOUTPUT(0): return hidraw_send_report(file, user_arg, len, HID_OUTPUT_REPORT); case HIDIOCGOUTPUT(0): return hidraw_get_report(file, user_arg, len, HID_OUTPUT_REPORT); } return -EINVAL; } static long hidraw_ro_variable_size_ioctl(struct file *file, struct hidraw *dev, unsigned int cmd, void __user *user_arg) { struct hid_device *hid = dev->hid; int len = _IOC_SIZE(cmd); int field_len; switch (cmd & ~IOCSIZE_MASK) { case HIDIOCGRAWNAME(0): field_len = strlen(hid->name) + 1; if (len > field_len) len = field_len; return copy_to_user(user_arg, hid->name, len) ? -EFAULT : len; case HIDIOCGRAWPHYS(0): field_len = strlen(hid->phys) + 1; if (len > field_len) len = field_len; return copy_to_user(user_arg, hid->phys, len) ? -EFAULT : len; case HIDIOCGRAWUNIQ(0):