![David Herrmann](/assets/img/avatar_default.png)
UHID allows short writes so user-space can omit unused fields. We
automatically set them to 0 in the kernel. However, the 64/32 bit
compat-handler didn't do that in the UHID_CREATE fallback. This will
reveal random kernel heap data (of random size, even) to user-space.
Fixes: befde0226a
('HID: uhid: make creating devices work on 64/32 systems')
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
639 lines
14 KiB
C
639 lines
14 KiB
C
/*
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* User-space I/O driver support for HID subsystem
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* Copyright (c) 2012 David Herrmann
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*/
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/*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*/
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#include <linux/atomic.h>
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#include <linux/compat.h>
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#include <linux/device.h>
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#include <linux/fs.h>
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#include <linux/hid.h>
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#include <linux/input.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/poll.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/uhid.h>
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#include <linux/wait.h>
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#define UHID_NAME "uhid"
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#define UHID_BUFSIZE 32
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struct uhid_device {
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struct mutex devlock;
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bool running;
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__u8 *rd_data;
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uint rd_size;
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struct hid_device *hid;
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struct uhid_event input_buf;
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wait_queue_head_t waitq;
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spinlock_t qlock;
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__u8 head;
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__u8 tail;
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struct uhid_event *outq[UHID_BUFSIZE];
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struct mutex report_lock;
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wait_queue_head_t report_wait;
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atomic_t report_done;
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atomic_t report_id;
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struct uhid_event report_buf;
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};
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static struct miscdevice uhid_misc;
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static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
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{
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__u8 newhead;
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newhead = (uhid->head + 1) % UHID_BUFSIZE;
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if (newhead != uhid->tail) {
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uhid->outq[uhid->head] = ev;
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uhid->head = newhead;
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wake_up_interruptible(&uhid->waitq);
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} else {
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hid_warn(uhid->hid, "Output queue is full\n");
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kfree(ev);
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}
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}
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static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
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{
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unsigned long flags;
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struct uhid_event *ev;
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ev = kzalloc(sizeof(*ev), GFP_KERNEL);
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if (!ev)
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return -ENOMEM;
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ev->type = event;
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spin_lock_irqsave(&uhid->qlock, flags);
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uhid_queue(uhid, ev);
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spin_unlock_irqrestore(&uhid->qlock, flags);
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return 0;
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}
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static int uhid_hid_start(struct hid_device *hid)
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{
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struct uhid_device *uhid = hid->driver_data;
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return uhid_queue_event(uhid, UHID_START);
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}
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static void uhid_hid_stop(struct hid_device *hid)
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{
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struct uhid_device *uhid = hid->driver_data;
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hid->claimed = 0;
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uhid_queue_event(uhid, UHID_STOP);
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}
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static int uhid_hid_open(struct hid_device *hid)
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{
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struct uhid_device *uhid = hid->driver_data;
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return uhid_queue_event(uhid, UHID_OPEN);
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}
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static void uhid_hid_close(struct hid_device *hid)
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{
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struct uhid_device *uhid = hid->driver_data;
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uhid_queue_event(uhid, UHID_CLOSE);
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}
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static int uhid_hid_parse(struct hid_device *hid)
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{
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struct uhid_device *uhid = hid->driver_data;
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return hid_parse_report(hid, uhid->rd_data, uhid->rd_size);
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}
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static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum,
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__u8 *buf, size_t count, unsigned char rtype)
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{
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struct uhid_device *uhid = hid->driver_data;
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__u8 report_type;
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struct uhid_event *ev;
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unsigned long flags;
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int ret;
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size_t uninitialized_var(len);
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struct uhid_feature_answer_req *req;
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if (!uhid->running)
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return -EIO;
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switch (rtype) {
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case HID_FEATURE_REPORT:
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report_type = UHID_FEATURE_REPORT;
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break;
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case HID_OUTPUT_REPORT:
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report_type = UHID_OUTPUT_REPORT;
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break;
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case HID_INPUT_REPORT:
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report_type = UHID_INPUT_REPORT;
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break;
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default:
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return -EINVAL;
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}
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ret = mutex_lock_interruptible(&uhid->report_lock);
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if (ret)
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return ret;
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ev = kzalloc(sizeof(*ev), GFP_KERNEL);
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if (!ev) {
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ret = -ENOMEM;
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goto unlock;
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}
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spin_lock_irqsave(&uhid->qlock, flags);
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ev->type = UHID_FEATURE;
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ev->u.feature.id = atomic_inc_return(&uhid->report_id);
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ev->u.feature.rnum = rnum;
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ev->u.feature.rtype = report_type;
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atomic_set(&uhid->report_done, 0);
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uhid_queue(uhid, ev);
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spin_unlock_irqrestore(&uhid->qlock, flags);
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ret = wait_event_interruptible_timeout(uhid->report_wait,
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atomic_read(&uhid->report_done), 5 * HZ);
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/*
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* Make sure "uhid->running" is cleared on shutdown before
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* "uhid->report_done" is set.
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*/
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smp_rmb();
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if (!ret || !uhid->running) {
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ret = -EIO;
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} else if (ret < 0) {
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ret = -ERESTARTSYS;
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} else {
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spin_lock_irqsave(&uhid->qlock, flags);
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req = &uhid->report_buf.u.feature_answer;
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if (req->err) {
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ret = -EIO;
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} else {
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ret = 0;
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len = min(count,
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min_t(size_t, req->size, UHID_DATA_MAX));
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memcpy(buf, req->data, len);
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}
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spin_unlock_irqrestore(&uhid->qlock, flags);
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}
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atomic_set(&uhid->report_done, 1);
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unlock:
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mutex_unlock(&uhid->report_lock);
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return ret ? ret : len;
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}
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static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
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unsigned char report_type)
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{
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struct uhid_device *uhid = hid->driver_data;
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__u8 rtype;
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unsigned long flags;
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struct uhid_event *ev;
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switch (report_type) {
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case HID_FEATURE_REPORT:
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rtype = UHID_FEATURE_REPORT;
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break;
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case HID_OUTPUT_REPORT:
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rtype = UHID_OUTPUT_REPORT;
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break;
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default:
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return -EINVAL;
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}
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if (count < 1 || count > UHID_DATA_MAX)
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return -EINVAL;
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ev = kzalloc(sizeof(*ev), GFP_KERNEL);
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if (!ev)
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return -ENOMEM;
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ev->type = UHID_OUTPUT;
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ev->u.output.size = count;
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ev->u.output.rtype = rtype;
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memcpy(ev->u.output.data, buf, count);
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spin_lock_irqsave(&uhid->qlock, flags);
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uhid_queue(uhid, ev);
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spin_unlock_irqrestore(&uhid->qlock, flags);
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return count;
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}
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static struct hid_ll_driver uhid_hid_driver = {
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.start = uhid_hid_start,
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.stop = uhid_hid_stop,
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.open = uhid_hid_open,
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.close = uhid_hid_close,
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.parse = uhid_hid_parse,
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};
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#ifdef CONFIG_COMPAT
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/* Apparently we haven't stepped on these rakes enough times yet. */
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struct uhid_create_req_compat {
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__u8 name[128];
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__u8 phys[64];
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__u8 uniq[64];
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compat_uptr_t rd_data;
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__u16 rd_size;
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__u16 bus;
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__u32 vendor;
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__u32 product;
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__u32 version;
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__u32 country;
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} __attribute__((__packed__));
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static int uhid_event_from_user(const char __user *buffer, size_t len,
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struct uhid_event *event)
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{
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if (is_compat_task()) {
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u32 type;
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if (get_user(type, buffer))
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return -EFAULT;
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if (type == UHID_CREATE) {
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/*
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* This is our messed up request with compat pointer.
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* It is largish (more than 256 bytes) so we better
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* allocate it from the heap.
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*/
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struct uhid_create_req_compat *compat;
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compat = kzalloc(sizeof(*compat), GFP_KERNEL);
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if (!compat)
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return -ENOMEM;
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buffer += sizeof(type);
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len -= sizeof(type);
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if (copy_from_user(compat, buffer,
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min(len, sizeof(*compat)))) {
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kfree(compat);
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return -EFAULT;
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}
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/* Shuffle the data over to proper structure */
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event->type = type;
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memcpy(event->u.create.name, compat->name,
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sizeof(compat->name));
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memcpy(event->u.create.phys, compat->phys,
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sizeof(compat->phys));
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memcpy(event->u.create.uniq, compat->uniq,
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sizeof(compat->uniq));
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event->u.create.rd_data = compat_ptr(compat->rd_data);
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event->u.create.rd_size = compat->rd_size;
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event->u.create.bus = compat->bus;
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event->u.create.vendor = compat->vendor;
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event->u.create.product = compat->product;
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event->u.create.version = compat->version;
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event->u.create.country = compat->country;
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kfree(compat);
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return 0;
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}
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/* All others can be copied directly */
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}
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if (copy_from_user(event, buffer, min(len, sizeof(*event))))
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return -EFAULT;
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return 0;
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}
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#else
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static int uhid_event_from_user(const char __user *buffer, size_t len,
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struct uhid_event *event)
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{
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if (copy_from_user(event, buffer, min(len, sizeof(*event))))
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return -EFAULT;
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return 0;
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}
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#endif
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static int uhid_dev_create(struct uhid_device *uhid,
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const struct uhid_event *ev)
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{
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struct hid_device *hid;
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int ret;
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if (uhid->running)
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return -EALREADY;
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uhid->rd_size = ev->u.create.rd_size;
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if (uhid->rd_size <= 0 || uhid->rd_size > HID_MAX_DESCRIPTOR_SIZE)
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return -EINVAL;
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uhid->rd_data = kmalloc(uhid->rd_size, GFP_KERNEL);
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if (!uhid->rd_data)
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return -ENOMEM;
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if (copy_from_user(uhid->rd_data, ev->u.create.rd_data,
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uhid->rd_size)) {
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ret = -EFAULT;
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goto err_free;
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}
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hid = hid_allocate_device();
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if (IS_ERR(hid)) {
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ret = PTR_ERR(hid);
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goto err_free;
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}
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strncpy(hid->name, ev->u.create.name, 127);
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hid->name[127] = 0;
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strncpy(hid->phys, ev->u.create.phys, 63);
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hid->phys[63] = 0;
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strncpy(hid->uniq, ev->u.create.uniq, 63);
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hid->uniq[63] = 0;
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hid->ll_driver = &uhid_hid_driver;
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hid->hid_get_raw_report = uhid_hid_get_raw;
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hid->hid_output_raw_report = uhid_hid_output_raw;
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hid->bus = ev->u.create.bus;
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hid->vendor = ev->u.create.vendor;
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hid->product = ev->u.create.product;
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hid->version = ev->u.create.version;
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hid->country = ev->u.create.country;
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hid->driver_data = uhid;
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hid->dev.parent = uhid_misc.this_device;
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uhid->hid = hid;
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uhid->running = true;
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ret = hid_add_device(hid);
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if (ret) {
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hid_err(hid, "Cannot register HID device\n");
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goto err_hid;
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}
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return 0;
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err_hid:
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hid_destroy_device(hid);
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uhid->hid = NULL;
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uhid->running = false;
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err_free:
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kfree(uhid->rd_data);
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return ret;
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}
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static int uhid_dev_destroy(struct uhid_device *uhid)
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{
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if (!uhid->running)
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return -EINVAL;
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/* clear "running" before setting "report_done" */
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uhid->running = false;
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smp_wmb();
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atomic_set(&uhid->report_done, 1);
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wake_up_interruptible(&uhid->report_wait);
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hid_destroy_device(uhid->hid);
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kfree(uhid->rd_data);
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return 0;
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}
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static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
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{
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if (!uhid->running)
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return -EINVAL;
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hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
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min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0);
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return 0;
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}
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static int uhid_dev_feature_answer(struct uhid_device *uhid,
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struct uhid_event *ev)
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{
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unsigned long flags;
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if (!uhid->running)
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return -EINVAL;
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spin_lock_irqsave(&uhid->qlock, flags);
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/* id for old report; drop it silently */
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if (atomic_read(&uhid->report_id) != ev->u.feature_answer.id)
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goto unlock;
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if (atomic_read(&uhid->report_done))
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goto unlock;
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memcpy(&uhid->report_buf, ev, sizeof(*ev));
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atomic_set(&uhid->report_done, 1);
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wake_up_interruptible(&uhid->report_wait);
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unlock:
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spin_unlock_irqrestore(&uhid->qlock, flags);
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return 0;
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}
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static int uhid_char_open(struct inode *inode, struct file *file)
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{
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struct uhid_device *uhid;
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uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
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if (!uhid)
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return -ENOMEM;
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mutex_init(&uhid->devlock);
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mutex_init(&uhid->report_lock);
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spin_lock_init(&uhid->qlock);
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init_waitqueue_head(&uhid->waitq);
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init_waitqueue_head(&uhid->report_wait);
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uhid->running = false;
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atomic_set(&uhid->report_done, 1);
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file->private_data = uhid;
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nonseekable_open(inode, file);
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return 0;
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}
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static int uhid_char_release(struct inode *inode, struct file *file)
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{
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struct uhid_device *uhid = file->private_data;
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unsigned int i;
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uhid_dev_destroy(uhid);
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for (i = 0; i < UHID_BUFSIZE; ++i)
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kfree(uhid->outq[i]);
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kfree(uhid);
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return 0;
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}
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static ssize_t uhid_char_read(struct file *file, char __user *buffer,
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size_t count, loff_t *ppos)
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{
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struct uhid_device *uhid = file->private_data;
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int ret;
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unsigned long flags;
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size_t len;
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/* they need at least the "type" member of uhid_event */
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if (count < sizeof(__u32))
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return -EINVAL;
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try_again:
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if (file->f_flags & O_NONBLOCK) {
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if (uhid->head == uhid->tail)
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return -EAGAIN;
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} else {
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ret = wait_event_interruptible(uhid->waitq,
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uhid->head != uhid->tail);
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if (ret)
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return ret;
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}
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ret = mutex_lock_interruptible(&uhid->devlock);
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if (ret)
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return ret;
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if (uhid->head == uhid->tail) {
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mutex_unlock(&uhid->devlock);
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goto try_again;
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} else {
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len = min(count, sizeof(**uhid->outq));
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if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) {
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ret = -EFAULT;
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} else {
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kfree(uhid->outq[uhid->tail]);
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uhid->outq[uhid->tail] = NULL;
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|
|
|
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:
|
|
ret = uhid_dev_create(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_FEATURE_ANSWER:
|
|
ret = uhid_dev_feature_answer(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 unsigned int uhid_char_poll(struct file *file, poll_table *wait)
|
|
{
|
|
struct uhid_device *uhid = file->private_data;
|
|
|
|
poll_wait(file, &uhid->waitq, wait);
|
|
|
|
if (uhid->head != uhid->tail)
|
|
return POLLIN | POLLRDNORM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
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,
|
|
};
|
|
|
|
static int __init uhid_init(void)
|
|
{
|
|
return misc_register(&uhid_misc);
|
|
}
|
|
|
|
static void __exit uhid_exit(void)
|
|
{
|
|
misc_deregister(&uhid_misc);
|
|
}
|
|
|
|
module_init(uhid_init);
|
|
module_exit(uhid_exit);
|
|
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);
|