// 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):
                field_len = strlen(hid->uniq) + 1;
                if (len > field_len)
                        len = field_len;
                return copy_to_user(user_arg, hid->uniq, len) ?  -EFAULT : len;
        }

        return -EINVAL;
}

static long hidraw_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        struct inode *inode = file_inode(file);
        unsigned int minor = iminor(inode);
        struct hidraw *dev;
        struct hidraw_list *list = file->private_data;
        void __user *user_arg = (void __user *)arg;
        int ret;

        down_read(&minors_rwsem);
        dev = hidraw_table[minor];
        if (!dev || !dev->exist || hidraw_is_revoked(list)) {
                ret = -ENODEV;
                goto out;
        }

        if (_IOC_TYPE(cmd) != 'H') {
                ret = -EINVAL;
                goto out;
        }

        if (_IOC_NR(cmd) > HIDIOCTL_LAST || _IOC_NR(cmd) == 0) {
                ret = -ENOTTY;
                goto out;
        }

        ret = hidraw_fixed_size_ioctl(file, dev, cmd, user_arg);
        if (ret != -EAGAIN)
                goto out;

        switch (_IOC_DIR(cmd)) {
        case (_IOC_READ | _IOC_WRITE):
                ret = hidraw_rw_variable_size_ioctl(file, dev, cmd, user_arg);
                break;
        case _IOC_READ:
                ret = hidraw_ro_variable_size_ioctl(file, dev, cmd, user_arg);
                break;
        default:
                /* Any other IOC_DIR is wrong */
                ret = -EINVAL;
        }

out:
        up_read(&minors_rwsem);
        return ret;
}

static const struct file_operations hidraw_ops = {
        .owner =        THIS_MODULE,
        .read =         hidraw_read,
        .write =        hidraw_write,
        .poll =         hidraw_poll,
        .open =         hidraw_open,
        .release =      hidraw_release,
        .unlocked_ioctl = hidraw_ioctl,
        .fasync =       hidraw_fasync,
        .compat_ioctl   = compat_ptr_ioctl,
        .llseek =       noop_llseek,
};

int hidraw_report_event(struct hid_device *hid, u8 *data, int len)
{
        struct hidraw *dev = hid->hidraw;
        struct hidraw_list *list;
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&dev->list_lock, flags);
        list_for_each_entry(list, &dev->list, node) {
                int new_head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);

                if (hidraw_is_revoked(list) || new_head == list->tail)
                        continue;

                if (!(list->buffer[list->head].value = kmemdup(data, len, GFP_ATOMIC))) {
                        ret = -ENOMEM;
                        break;
                }
                list->buffer[list->head].len = len;
                list->head = new_head;
                kill_fasync(&list->fasync, SIGIO, POLL_IN);
        }
        spin_unlock_irqrestore(&dev->list_lock, flags);

        wake_up_interruptible(&dev->wait);
        return ret;
}
EXPORT_SYMBOL_GPL(hidraw_report_event);

int hidraw_connect(struct hid_device *hid)
{
        int minor, result;
        struct hidraw *dev;

        /* we accept any HID device, all applications */

        dev = kzalloc_obj(struct hidraw);
        if (!dev)
                return -ENOMEM;

        result = -EINVAL;

        down_write(&minors_rwsem);

        for (minor = 0; minor < HIDRAW_MAX_DEVICES; minor++) {
                if (hidraw_table[minor])
                        continue;
                hidraw_table[minor] = dev;
                result = 0;
                break;
        }

        if (result) {
                up_write(&minors_rwsem);
                kfree(dev);
                goto out;
        }

        dev->dev = device_create(&hidraw_class, &hid->dev, MKDEV(hidraw_major, minor),
                                 NULL, "%s%d", "hidraw", minor);

        if (IS_ERR(dev->dev)) {
                hidraw_table[minor] = NULL;
                up_write(&minors_rwsem);
                result = PTR_ERR(dev->dev);
                kfree(dev);
                goto out;
        }

        init_waitqueue_head(&dev->wait);
        spin_lock_init(&dev->list_lock);
        INIT_LIST_HEAD(&dev->list);

        dev->hid = hid;
        dev->minor = minor;

        dev->exist = 1;
        hid->hidraw = dev;

        up_write(&minors_rwsem);
out:
        return result;

}
EXPORT_SYMBOL_GPL(hidraw_connect);

void hidraw_disconnect(struct hid_device *hid)
{
        struct hidraw *hidraw = hid->hidraw;

        down_write(&minors_rwsem);

        drop_ref(hidraw, 1);

        up_write(&minors_rwsem);
}
EXPORT_SYMBOL_GPL(hidraw_disconnect);

int __init hidraw_init(void)
{
        int result;
        dev_t dev_id;

        result = alloc_chrdev_region(&dev_id, HIDRAW_FIRST_MINOR,
                        HIDRAW_MAX_DEVICES, "hidraw");
        if (result < 0) {
                pr_warn("can't get major number\n");
                goto out;
        }

        hidraw_major = MAJOR(dev_id);

        result = class_register(&hidraw_class);
        if (result)
                goto error_cdev;

        cdev_init(&hidraw_cdev, &hidraw_ops);
        result = cdev_add(&hidraw_cdev, dev_id, HIDRAW_MAX_DEVICES);
        if (result < 0)
                goto error_class;

        pr_info("raw HID events driver (C) Jiri Kosina\n");
out:
        return result;

error_class:
        class_unregister(&hidraw_class);
error_cdev:
        unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);
        goto out;
}

void hidraw_exit(void)
{
        dev_t dev_id = MKDEV(hidraw_major, 0);

        cdev_del(&hidraw_cdev);
        class_unregister(&hidraw_class);
        unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);

}