Message-ID: <CANq1E4TLDMjbfMY-rOM7M8VE_EKejk5DmbPF_BgwNtRwbJV-Aw@mail.gmail.com>
Date:	Sun, 25 Oct 2015 10:39:10 +0100
From:	David Herrmann <dh.herrmann@...il.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Benjamin Tissoires <benjamin.tissoires@...hat.com>,
	Peter Hutterer <peter.hutterer@...-t.net>,
	"open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] Input: uinput - add new UINPUT_DEV_SETUP and
 UI_ABS_SETUP ioctl

Hi

On Sun, Oct 25, 2015 at 12:53 AM, Dmitry Torokhov
<dmitry.torokhov@...il.com> wrote:
> Hi Benjamin,
>
> On Tue, Aug 25, 2015 at 11:12:59AM -0400, Benjamin Tissoires wrote:
>> +static int uinput_abs_setup(struct uinput_device *udev,
>> +                         struct uinput_setup __user *arg, size_t size)
>> +{
>> +     struct uinput_abs_setup setup = {};
>> +     struct input_dev *dev;
>> +
>> +     if (size > sizeof(setup))
>> +             return -E2BIG;
>> +     if (udev->state == UIST_CREATED)
>> +             return -EINVAL;
>> +     if (copy_from_user(&setup, arg, size))
>> +             return -EFAULT;
>> +     if (setup.code > ABS_MAX)
>> +             return -ERANGE;
>> +
>> +     dev = udev->dev;
>> +
>> +     input_alloc_absinfo(dev);
>> +     if (!dev->absinfo)
>> +             return -ENOMEM;
>> +
>> +     set_bit(setup.code, dev->absbit);
>> +     dev->absinfo[setup.code] = setup.absinfo;
>> +
>> +     /*
>> +      * We restore the state to UIST_NEW_DEVICE because the user has to call
>> +      * UI_DEV_SETUP in the last place before UI_DEV_CREATE to check the
>> +      * validity of the absbits.
>> +      */
>
> Do we have to be this strict? It seems to me that with the new IOCTLs
> you naturally want to use the new ioctl to setup the device, then adjust
> various axes and bits and then validate everything.

Indeed, we now force the order to be abs-setup first, then
device-setup as last step. Appended is a follow-up patch to cleanup
ABS handling in uinput. It is untested. Benjamin, care to give it a
spin?

Thanks
David

----
>From 2568f83bcc5c4b8aeb149be2c5fc5a743812f0fe Mon Sep 17 00:00:00 2001
From: David Herrmann <dh.herrmann@...il.com>
Date: Sun, 25 Oct 2015 10:34:13 +0100
Subject: [PATCH] Input: uinput - rework ABS validation

Rework the uinput ABS validation to check passed absinfo data
immediately, but do ABS initialization as last step in UI_DEV_CREATE. The
behavior observed by user-space is not changed, as ABS initialization was
never checked for errors.

With this in place, the order of device-initialization and
abs-configuration is no longer fixed. User-space can initialize the
device and afterwards set absinfo just fine.

Signed-off-by: David Herrmann <dh.herrmann@...il.com>
---
 drivers/input/misc/uinput.c | 89 +++++++++++++++++++++++----------------------
 1 file changed, 45 insertions(+), 44 deletions(-)

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index baac903..1d93037 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -256,13 +256,22 @@ static void uinput_destroy_device(...)
 static int uinput_create_device(struct uinput_device *udev)
 {
  struct input_dev *dev = udev->dev;
- int error;
+ int error, nslot;

  if (udev->state != UIST_SETUP_COMPLETE) {
  printk(KERN_DEBUG "%s: write device info first\n", UINPUT_NAME);
  return -EINVAL;
  }

+ if (test_bit(ABS_MT_SLOT, dev->absbit)) {
+ nslot = input_abs_get_max(dev, ABS_MT_SLOT) + 1;
+ error = input_mt_init_slots(dev, nslot, 0);
+ if (error)
+ goto fail1;
+ } else if (test_bit(ABS_MT_POSITION_X, dev->absbit)) {
+ input_set_events_per_packet(dev, 60);
+ }
+
  if (udev->ff_effects_max) {
  error = input_ff_create(dev, udev->ff_effects_max);
  if (error)
@@ -308,10 +317,35 @@ static int uinput_open(...)
  return 0;
 }

+static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
+   const struct input_absinfo *abs)
+{
+ int min, max;
+
+ min = abs->minimum;
+ max = abs->maximum;
+
+ if ((min != 0 || max != 0) && max <= min) {
+ printk(KERN_DEBUG
+       "%s: invalid abs[%02x] min:%d max:%d\n",
+       UINPUT_NAME, code, min, max);
+ return -EINVAL;
+ }
+
+ if (abs->flat > max - min) {
+ printk(KERN_DEBUG
+       "%s: abs_flat #%02x out of range: %d (min:%d/max:%d)\n",
+       UINPUT_NAME, code, abs->flat, min, max);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
 static int uinput_validate_absbits(struct input_dev *dev)
 {
  unsigned int cnt;
- int nslot;
+ int error;

  if (!test_bit(EV_ABS, dev->evbit))
  return 0;
@@ -321,38 +355,12 @@ static int uinput_validate_absbits(struct input_dev *dev)
  */

  for_each_set_bit(cnt, dev->absbit, ABS_CNT) {
- int min, max;
-
- min = input_abs_get_min(dev, cnt);
- max = input_abs_get_max(dev, cnt);
-
- if ((min != 0 || max != 0) && max <= min) {
- printk(KERN_DEBUG
- "%s: invalid abs[%02x] min:%d max:%d\n",
- UINPUT_NAME, cnt,
- input_abs_get_min(dev, cnt),
- input_abs_get_max(dev, cnt));
+ if (!dev->absinfo)
  return -EINVAL;
- }
-
- if (input_abs_get_flat(dev, cnt) >
-    input_abs_get_max(dev, cnt) - input_abs_get_min(dev, cnt)) {
- printk(KERN_DEBUG
- "%s: abs_flat #%02x out of range: %d "
- "(min:%d/max:%d)\n",
- UINPUT_NAME, cnt,
- input_abs_get_flat(dev, cnt),
- input_abs_get_min(dev, cnt),
- input_abs_get_max(dev, cnt));
- return -EINVAL;
- }
- }

- if (test_bit(ABS_MT_SLOT, dev->absbit)) {
- nslot = input_abs_get_max(dev, ABS_MT_SLOT) + 1;
- input_mt_init_slots(dev, nslot, 0);
- } else if (test_bit(ABS_MT_POSITION_X, dev->absbit)) {
- input_set_events_per_packet(dev, 60);
+ error = uinput_validate_absinfo(dev, cnt, &dev->absinfo[cnt]);
+ if (error)
+ return error;
  }

  return 0;
@@ -375,7 +383,6 @@ static int uinput_dev_setup(struct uinput_device *udev,
 {
  struct uinput_setup setup;
  struct input_dev *dev;
- int retval;

  if (udev->state == UIST_CREATED)
  return -EINVAL;
@@ -393,10 +400,6 @@ static int uinput_dev_setup(struct uinput_device *udev,
  if (!dev->name)
  return -ENOMEM;

- retval = uinput_validate_absbits(dev);
- if (retval < 0)
- return retval;
-
  udev->state = UIST_SETUP_COMPLETE;
  return 0;
 }
@@ -406,6 +409,7 @@ static int uinput_abs_setup(struct uinput_device *udev,
 {
  struct uinput_abs_setup setup = {};
  struct input_dev *dev;
+ int error;

  if (size > sizeof(setup))
  return -E2BIG;
@@ -418,19 +422,16 @@ static int uinput_abs_setup(struct uinput_device *udev,

  dev = udev->dev;

+ error = uinput_validate_absinfo(dev, setup.code, &setup.absinfo);
+ if (error)
+ return error;
+
  input_alloc_absinfo(dev);
  if (!dev->absinfo)
  return -ENOMEM;

  set_bit(setup.code, dev->absbit);
  dev->absinfo[setup.code] = setup.absinfo;
-
- /*
- * We restore the state to UIST_NEW_DEVICE because the user has to call
- * UI_DEV_SETUP in the last place before UI_DEV_CREATE to check the
- * validity of the absbits.
- */
- udev->state = UIST_NEW_DEVICE;
  return 0;
 }

-- 
2.6.1

View attachment "0001-Input-uinput-rework-ABS-validation.patch" of type "text/x-patch" (4943 bytes)

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