diff options
Diffstat (limited to 'drivers/hid/uhid.c')
| -rw-r--r-- | drivers/hid/uhid.c | 821 |
1 files changed, 821 insertions, 0 deletions
diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c new file mode 100644 index 0000000000..4588d2cd4e --- /dev/null +++ b/drivers/hid/uhid.c @@ -0,0 +1,821 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * User-space I/O driver support for HID subsystem + * Copyright (c) 2012 David Herrmann + */ + +/* + */ + +#include <linux/atomic.h> +#include <linux/compat.h> +#include <linux/cred.h> +#include <linux/device.h> +#include <linux/fs.h> +#include <linux/hid.h> +#include <linux/input.h> +#include <linux/miscdevice.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/poll.h> +#include <linux/sched.h> +#include <linux/spinlock.h> +#include <linux/uhid.h> +#include <linux/wait.h> + +#define UHID_NAME "uhid" +#define UHID_BUFSIZE 32 + +struct uhid_device { + struct mutex devlock; + + /* This flag tracks whether the HID device is usable for commands from + * userspace. The flag is already set before hid_add_device(), which + * runs in workqueue context, to allow hid_add_device() to communicate + * with userspace. + * However, if hid_add_device() fails, the flag is cleared without + * holding devlock. + * We guarantee that if @running changes from true to false while you're + * holding @devlock, it's still fine to access @hid. + */ + bool running; + + __u8 *rd_data; + uint rd_size; + + /* When this is NULL, userspace may use UHID_CREATE/UHID_CREATE2. */ + struct hid_device *hid; + struct uhid_event input_buf; + + wait_queue_head_t waitq; + spinlock_t qlock; + __u8 head; + __u8 tail; + struct uhid_event *outq[UHID_BUFSIZE]; + + /* blocking GET_REPORT support; state changes protected by qlock */ + struct mutex report_lock; + wait_queue_head_t report_wait; + bool report_running; + u32 report_id; + u32 report_type; + struct uhid_event report_buf; + struct work_struct worker; +}; + +static struct miscdevice uhid_misc; + +static void uhid_device_add_worker(struct work_struct *work) +{ + struct uhid_device *uhid = container_of(work, struct uhid_device, worker); + int ret; + + ret = hid_add_device(uhid->hid); + if (ret) { + hid_err(uhid->hid, "Cannot register HID device: error %d\n", ret); + + /* We used to call hid_destroy_device() here, but that's really + * messy to get right because we have to coordinate with + * concurrent writes from userspace that might be in the middle + * of using uhid->hid. + * Just leave uhid->hid as-is for now, and clean it up when + * userspace tries to close or reinitialize the uhid instance. + * + * However, we do have to clear the ->running flag and do a + * wakeup to make sure userspace knows that the device is gone. + */ + WRITE_ONCE(uhid->running, false); + wake_up_interruptible(&uhid->report_wait); + } +} + +static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev) +{ + __u8 newhead; + + newhead = (uhid->head + 1) % UHID_BUFSIZE; + + if (newhead != uhid->tail) { + uhid->outq[uhid->head] = ev; + uhid->head = newhead; + wake_up_interruptible(&uhid->waitq); + } else { + hid_warn(uhid->hid, "Output queue is full\n"); + kfree(ev); + } +} + +static int uhid_queue_event(struct uhid_device *uhid, __u32 event) +{ + unsigned long flags; + struct uhid_event *ev; + + ev = kzalloc(sizeof(*ev), GFP_KERNEL); + if (!ev) + return -ENOMEM; + + ev->type = event; + + spin_lock_irqsave(&uhid->qlock, flags); + uhid_queue(uhid, ev); + spin_unlock_irqrestore(&uhid->qlock, flags); + + return 0; +} + +static int uhid_hid_start(struct hid_device *hid) +{ + struct uhid_device *uhid = hid->driver_data; + struct uhid_event *ev; + unsigned long flags; + + ev = kzalloc(sizeof(*ev), GFP_KERNEL); + if (!ev) + return -ENOMEM; + + ev->type = UHID_START; + + if (hid->report_enum[HID_FEATURE_REPORT].numbered) + ev->u.start.dev_flags |= UHID_DEV_NUMBERED_FEATURE_REPORTS; + if (hid->report_enum[HID_OUTPUT_REPORT].numbered) + ev->u.start.dev_flags |= UHID_DEV_NUMBERED_OUTPUT_REPORTS; + if (hid->report_enum[HID_INPUT_REPORT].numbered) + ev->u.start.dev_flags |= UHID_DEV_NUMBERED_INPUT_REPORTS; + + spin_lock_irqsave(&uhid->qlock, flags); + uhid_queue(uhid, ev); + spin_unlock_irqrestore(&uhid->qlock, flags); + + return 0; +} + +static void uhid_hid_stop(struct hid_device *hid) +{ + struct uhid_device *uhid = hid->driver_data; + + hid->claimed = 0; + uhid_queue_event(uhid, UHID_STOP); +} + +static int uhid_hid_open(struct hid_device *hid) +{ + struct uhid_device *uhid = hid->driver_data; + + return uhid_queue_event(uhid, UHID_OPEN); +} + +static void uhid_hid_close(struct hid_device *hid) +{ + struct uhid_device *uhid = hid->driver_data; + + uhid_queue_event(uhid, UHID_CLOSE); +} + +static int uhid_hid_parse(struct hid_device *hid) +{ + struct uhid_device *uhid = hid->driver_data; + + return hid_parse_report(hid, uhid->rd_data, uhid->rd_size); +} + +/* must be called with report_lock held */ +static int __uhid_report_queue_and_wait(struct uhid_device *uhid, + struct uhid_event *ev, + __u32 *report_id) +{ + unsigned long flags; + int ret; + + spin_lock_irqsave(&uhid->qlock, flags); + *report_id = ++uhid->report_id; + uhid->report_type = ev->type + 1; + uhid->report_running = true; + uhid_queue(uhid, ev); + spin_unlock_irqrestore(&uhid->qlock, flags); + + ret = wait_event_interruptible_timeout(uhid->report_wait, + !uhid->report_running || !READ_ONCE(uhid->running), + 5 * HZ); + if (!ret || !READ_ONCE(uhid->running) || uhid->report_running) + ret = -EIO; + else if (ret < 0) + ret = -ERESTARTSYS; + else + ret = 0; + + uhid->report_running = false; + + return ret; +} + +static void uhid_report_wake_up(struct uhid_device *uhid, u32 id, + const struct uhid_event *ev) +{ + unsigned long flags; + + spin_lock_irqsave(&uhid->qlock, flags); + + /* id for old report; drop it silently */ + if (uhid->report_type != ev->type || uhid->report_id != id) + goto unlock; + if (!uhid->report_running) + goto unlock; + + memcpy(&uhid->report_buf, ev, sizeof(*ev)); + uhid->report_running = false; + wake_up_interruptible(&uhid->report_wait); + +unlock: + spin_unlock_irqrestore(&uhid->qlock, flags); +} + +static int uhid_hid_get_report(struct hid_device *hid, unsigned char rnum, + u8 *buf, size_t count, u8 rtype) +{ + struct uhid_device *uhid = hid->driver_data; + struct uhid_get_report_reply_req *req; + struct uhid_event *ev; + int ret; + + if (!READ_ONCE(uhid->running)) + return -EIO; + + ev = kzalloc(sizeof(*ev), GFP_KERNEL); + if (!ev) + return -ENOMEM; + + ev->type = UHID_GET_REPORT; + ev->u.get_report.rnum = rnum; + ev->u.get_report.rtype = rtype; + + ret = mutex_lock_interruptible(&uhid->report_lock); + if (ret) { + kfree(ev); + return ret; + } + + /* this _always_ takes ownership of @ev */ + ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.get_report.id); + if (ret) + goto unlock; + + req = &uhid->report_buf.u.get_report_reply; + if (req->err) { + ret = -EIO; + } else { + ret = min3(count, (size_t)req->size, (size_t)UHID_DATA_MAX); + memcpy(buf, req->data, ret); + } + +unlock: + mutex_unlock(&uhid->report_lock); + return ret; +} + +static int uhid_hid_set_report(struct hid_device *hid, unsigned char rnum, + const u8 *buf, size_t count, u8 rtype) +{ + struct uhid_device *uhid = hid->driver_data; + struct uhid_event *ev; + int ret; + + if (!READ_ONCE(uhid->running) || count > UHID_DATA_MAX) + return -EIO; + + ev = kzalloc(sizeof(*ev), GFP_KERNEL); + if (!ev) + return -ENOMEM; + + ev->type = UHID_SET_REPORT; + ev->u.set_report.rnum = rnum; + ev->u.set_report.rtype = rtype; + ev->u.set_report.size = count; + memcpy(ev->u.set_report.data, buf, count); + + ret = mutex_lock_interruptible(&uhid->report_lock); + if (ret) { + kfree(ev); + return ret; + } + + /* this _always_ takes ownership of @ev */ + ret = __uhid_report_queue_and_wait(uhid, ev, &ev->u.set_report.id); + if (ret) + goto unlock; + + if (uhid->report_buf.u.set_report_reply.err) + ret = -EIO; + else + ret = count; + +unlock: + mutex_unlock(&uhid->report_lock); + return ret; +} + +static int uhid_hid_raw_request(struct hid_device *hid, unsigned char reportnum, + __u8 *buf, size_t len, unsigned char rtype, + int reqtype) +{ + u8 u_rtype; + + switch (rtype) { + case HID_FEATURE_REPORT: + u_rtype = UHID_FEATURE_REPORT; + break; + case HID_OUTPUT_REPORT: + u_rtype = UHID_OUTPUT_REPORT; + break; + case HID_INPUT_REPORT: + u_rtype = UHID_INPUT_REPORT; + break; + default: + return -EINVAL; + } + + switch (reqtype) { + case HID_REQ_GET_REPORT: + return uhid_hid_get_report(hid, reportnum, buf, len, u_rtype); + case HID_REQ_SET_REPORT: + return uhid_hid_set_report(hid, reportnum, buf, len, u_rtype); + default: + return -EIO; + } +} + +static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count, + unsigned char report_type) +{ + struct uhid_device *uhid = hid->driver_data; + __u8 rtype; + unsigned long flags; + struct uhid_event *ev; + + switch (report_type) { + case HID_FEATURE_REPORT: + rtype = UHID_FEATURE_REPORT; + break; + case HID_OUTPUT_REPORT: + rtype = UHID_OUTPUT_REPORT; + break; + default: + return -EINVAL; + } + + if (count < 1 || count > UHID_DATA_MAX) + return -EINVAL; + + ev = kzalloc(sizeof(*ev), GFP_KERNEL); + if (!ev) + return -ENOMEM; + + ev->type = UHID_OUTPUT; + ev->u.output.size = count; + ev->u.output.rtype = rtype; + memcpy(ev->u.output.data, buf, count); + + spin_lock_irqsave(&uhid->qlock, flags); + uhid_queue(uhid, ev); + spin_unlock_irqrestore(&uhid->qlock, flags); + + return count; +} + +static int uhid_hid_output_report(struct hid_device *hid, __u8 *buf, + size_t count) +{ + return uhid_hid_output_raw(hid, buf, count, HID_OUTPUT_REPORT); +} + +static const struct hid_ll_driver uhid_hid_driver = { + .start = uhid_hid_start, + .stop = uhid_hid_stop, + .open = uhid_hid_open, + .close = uhid_hid_close, + .parse = uhid_hid_parse, + .raw_request = uhid_hid_raw_request, + .output_report = uhid_hid_output_report, + .max_buffer_size = UHID_DATA_MAX, +}; + +#ifdef CONFIG_COMPAT + +/* Apparently we haven't stepped on these rakes enough times yet. */ +struct uhid_create_req_compat { + __u8 name[128]; + __u8 phys[64]; + __u8 uniq[64]; + + compat_uptr_t rd_data; + __u16 rd_size; + + __u16 bus; + __u32 vendor; + __u32 product; + __u32 version; + __u32 country; +} __attribute__((__packed__)); + +static int uhid_event_from_user(const char __user *buffer, size_t len, + struct uhid_event *event) +{ + if (in_compat_syscall()) { + u32 type; + + if (get_user(type, buffer)) + return -EFAULT; + + if (type == UHID_CREATE) { + /* + * This is our messed up request with compat pointer. + * It is largish (more than 256 bytes) so we better + * allocate it from the heap. + */ + struct uhid_create_req_compat *compat; + + compat = kzalloc(sizeof(*compat), GFP_KERNEL); + if (!compat) + return -ENOMEM; + + buffer += sizeof(type); + len -= sizeof(type); + if (copy_from_user(compat, buffer, + min(len, sizeof(*compat)))) { + kfree(compat); + return -EFAULT; + } + + /* Shuffle the data over to proper structure */ + event->type = type; + + memcpy(event->u.create.name, compat->name, + sizeof(compat->name)); + memcpy(event->u.create.phys, compat->phys, + sizeof(compat->phys)); + memcpy(event->u.create.uniq, compat->uniq, + sizeof(compat->uniq)); + + event->u.create.rd_data = compat_ptr(compat->rd_data); + event->u.create.rd_size = compat->rd_size; + + event->u.create.bus = compat->bus; + event->u.create.vendor = compat->vendor; + event->u.create.product = compat->product; + event->u.create.version = compat->version; + event->u.create.country = compat->country; + + kfree(compat); + return 0; + } + /* All others can be copied directly */ + } + + if (copy_from_user(event, buffer, min(len, sizeof(*event)))) + return -EFAULT; + + return 0; +} +#else +static int uhid_event_from_user(const char __user *buffer, size_t len, + struct uhid_event *event) +{ + if (copy_from_user(event, buffer, min(len, sizeof(*event)))) + return -EFAULT; + + return 0; +} +#endif + +static int uhid_dev_create2(struct uhid_device *uhid, + const struct uhid_event *ev) +{ + struct hid_device *hid; + size_t rd_size, len; + void *rd_data; + int ret; + + if (uhid->hid) + return -EALREADY; + + rd_size = ev->u.create2.rd_size; + if (rd_size <= 0 || rd_size > HID_MAX_DESCRIPTOR_SIZE) + return -EINVAL; + + rd_data = kmemdup(ev->u.create2.rd_data, rd_size, GFP_KERNEL); + if (!rd_data) + return -ENOMEM; + + uhid->rd_size = rd_size; + uhid->rd_data = rd_data; + + hid = hid_allocate_device(); + if (IS_ERR(hid)) { + ret = PTR_ERR(hid); + goto err_free; + } + + /* @hid is zero-initialized, strncpy() is correct, strlcpy() not */ + len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1; + strncpy(hid->name, ev->u.create2.name, len); + len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1; + strncpy(hid->phys, ev->u.create2.phys, len); + len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1; + strncpy(hid->uniq, ev->u.create2.uniq, len); + + hid->ll_driver = &uhid_hid_driver; + hid->bus = ev->u.create2.bus; + hid->vendor = ev->u.create2.vendor; + hid->product = ev->u.create2.product; + hid->version = ev->u.create2.version; + hid->country = ev->u.create2.country; + hid->driver_data = uhid; + hid->dev.parent = uhid_misc.this_device; + + uhid->hid = hid; + uhid->running = true; + + /* Adding of a HID device is done through a worker, to allow HID drivers + * which use feature requests during .probe to work, without they would + * be blocked on devlock, which is held by uhid_char_write. + */ + schedule_work(&uhid->worker); + + return 0; + +err_free: + kfree(uhid->rd_data); + uhid->rd_data = NULL; + uhid->rd_size = 0; + return ret; +} + +static int uhid_dev_create(struct uhid_device *uhid, + struct uhid_event *ev) +{ + struct uhid_create_req orig; + + orig = ev->u.create; + + if (orig.rd_size <= 0 || orig.rd_size > HID_MAX_DESCRIPTOR_SIZE) + return -EINVAL; + if (copy_from_user(&ev->u.create2.rd_data, orig.rd_data, orig.rd_size)) + return -EFAULT; + + memcpy(ev->u.create2.name, orig.name, sizeof(orig.name)); + memcpy(ev->u.create2.phys, orig.phys, sizeof(orig.phys)); + memcpy(ev->u.create2.uniq, orig.uniq, sizeof(orig.uniq)); + ev->u.create2.rd_size = orig.rd_size; + ev->u.create2.bus = orig.bus; + ev->u.create2.vendor = orig.vendor; + ev->u.create2.product = orig.product; + ev->u.create2.version = orig.version; + ev->u.create2.country = orig.country; + + return uhid_dev_create2(uhid, ev); +} + +static int uhid_dev_destroy(struct uhid_device *uhid) +{ + if (!uhid->hid) + return -EINVAL; + + WRITE_ONCE(uhid->running, false); + wake_up_interruptible(&uhid->report_wait); + + cancel_work_sync(&uhid->worker); + + hid_destroy_device(uhid->hid); + uhid->hid = NULL; + kfree(uhid->rd_data); + + return 0; +} + +static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev) +{ + if (!READ_ONCE(uhid->running)) + return -EINVAL; + + hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data, + min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0); + + return 0; +} + +static int uhid_dev_input2(struct uhid_device *uhid, struct uhid_event *ev) +{ + if (!READ_ONCE(uhid->running)) + return -EINVAL; + + hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input2.data, + min_t(size_t, ev->u.input2.size, UHID_DATA_MAX), 0); + + return 0; +} + +static int uhid_dev_get_report_reply(struct uhid_device *uhid, + struct uhid_event *ev) +{ + if (!READ_ONCE(uhid->running)) + return -EINVAL; + + uhid_report_wake_up(uhid, ev->u.get_report_reply.id, ev); + return 0; +} + +static int uhid_dev_set_report_reply(struct uhid_device *uhid, + struct uhid_event *ev) +{ + if (!READ_ONCE(uhid->running)) + return -EINVAL; + + uhid_report_wake_up(uhid, ev->u.set_report_reply.id, ev); + return 0; +} + +static int uhid_char_open(struct inode *inode, struct file *file) +{ + struct uhid_device *uhid; + + uhid = kzalloc(sizeof(*uhid), GFP_KERNEL); + if (!uhid) + return -ENOMEM; + + mutex_init(&uhid->devlock); + mutex_init(&uhid->report_lock); + spin_lock_init(&uhid->qlock); + init_waitqueue_head(&uhid->waitq); + init_waitqueue_head(&uhid->report_wait); + uhid->running = false; + INIT_WORK(&uhid->worker, uhid_device_add_worker); + + file->private_data = uhid; + stream_open(inode, file); + + return 0; +} + +static int uhid_char_release(struct inode *inode, struct file *file) +{ + struct uhid_device *uhid = file->private_data; + unsigned int i; + + uhid_dev_destroy(uhid); + + for (i = 0; i < UHID_BUFSIZE; ++i) + kfree(uhid->outq[i]); + + kfree(uhid); + + return 0; +} + +static ssize_t uhid_char_read(struct file *file, char __user *buffer, + size_t count, loff_t *ppos) +{ + struct uhid_device *uhid = file->private_data; + int ret; + unsigned long flags; + size_t len; + + /* they need at least the "type" member of uhid_event */ + if (count < sizeof(__u32)) + return -EINVAL; + +try_again: + if (file->f_flags & O_NONBLOCK) { + if (uhid->head == uhid->tail) + return -EAGAIN; + } else { + ret = wait_event_interruptible(uhid->waitq, + uhid->head != uhid->tail); + if (ret) + return ret; + } + + ret = mutex_lock_interruptible(&uhid->devlock); + if (ret) + return ret; + + if (uhid->head == uhid->tail) { + mutex_unlock(&uhid->devlock); + goto try_again; + } else { + len = min(count, sizeof(**uhid->outq)); + if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) { + ret = -EFAULT; + } else { + kfree(uhid->outq[uhid->tail]); + uhid->outq[uhid->tail] = NULL; + + spin_lock_irqsave(&uhid->qlock, flags); + uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE; + spin_unlock_irqrestore(&uhid->qlock, flags); + } + } + + mutex_unlock(&uhid->devlock); + return ret ? ret : len; +} + +static ssize_t uhid_char_write(struct file *file, const char __user *buffer, + size_t count, loff_t *ppos) +{ + struct uhid_device *uhid = file->private_data; + int ret; + size_t len; + + /* we need at least the "type" member of uhid_event */ + if (count < sizeof(__u32)) + return -EINVAL; + + ret = mutex_lock_interruptible(&uhid->devlock); + if (ret) + return ret; + + memset(&uhid->input_buf, 0, sizeof(uhid->input_buf)); + len = min(count, sizeof(uhid->input_buf)); + + ret = uhid_event_from_user(buffer, len, &uhid->input_buf); + if (ret) + goto unlock; + + switch (uhid->input_buf.type) { + case UHID_CREATE: + /* + * 'struct uhid_create_req' contains a __user pointer which is + * copied from, so it's unsafe to allow this with elevated + * privileges (e.g. from a setuid binary) or via kernel_write(). + */ + if (file->f_cred != current_cred()) { + pr_err_once("UHID_CREATE from different security context by process %d (%s), this is not allowed.\n", + task_tgid_vnr(current), current->comm); + ret = -EACCES; + goto unlock; + } + ret = uhid_dev_create(uhid, &uhid->input_buf); + break; + case UHID_CREATE2: + ret = uhid_dev_create2(uhid, &uhid->input_buf); + break; + case UHID_DESTROY: + ret = uhid_dev_destroy(uhid); + break; + case UHID_INPUT: + ret = uhid_dev_input(uhid, &uhid->input_buf); + break; + case UHID_INPUT2: + ret = uhid_dev_input2(uhid, &uhid->input_buf); + break; + case UHID_GET_REPORT_REPLY: + ret = uhid_dev_get_report_reply(uhid, &uhid->input_buf); + break; + case UHID_SET_REPORT_REPLY: + ret = uhid_dev_set_report_reply(uhid, &uhid->input_buf); + break; + default: + ret = -EOPNOTSUPP; + } + +unlock: + mutex_unlock(&uhid->devlock); + + /* return "count" not "len" to not confuse the caller */ + return ret ? ret : count; +} + +static __poll_t uhid_char_poll(struct file *file, poll_table *wait) +{ + struct uhid_device *uhid = file->private_data; + __poll_t mask = EPOLLOUT | EPOLLWRNORM; /* uhid is always writable */ + + poll_wait(file, &uhid->waitq, wait); + + if (uhid->head != uhid->tail) + mask |= EPOLLIN | EPOLLRDNORM; + + return mask; +} + +static const struct file_operations uhid_fops = { + .owner = THIS_MODULE, + .open = uhid_char_open, + .release = uhid_char_release, + .read = uhid_char_read, + .write = uhid_char_write, + .poll = uhid_char_poll, + .llseek = no_llseek, +}; + +static struct miscdevice uhid_misc = { + .fops = &uhid_fops, + .minor = UHID_MINOR, + .name = UHID_NAME, +}; +module_misc_device(uhid_misc); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>"); +MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem"); +MODULE_ALIAS_MISCDEV(UHID_MINOR); +MODULE_ALIAS("devname:" UHID_NAME); |