| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20180228224926.GA7009@casa>
Date: Wed, 28 Feb 2018 23:49:26 +0100
From: Rodrigo Rivas Costa <rodrigorivascosta@...il.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Jiri Kosina <jikos@...nel.org>,
Benjamin Tissoires <benjamin.tissoires@...hat.com>,
"Pierre-Loup A. Griffais" <pgriffais@...vesoftware.com>,
Cameron Gutman <aicommander@...il.com>,
Clément VUCHENER <clement.vuchener@...il.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-input <linux-input@...r.kernel.org>
Subject: Re: [PATCH v4 1/4] HID: add driver for Valve Steam Controller
On Wed, Feb 28, 2018 at 09:21:15PM +0200, Andy Shevchenko wrote:
> On Wed, Feb 28, 2018 at 8:43 PM, Rodrigo Rivas Costa
> <rodrigorivascosta@...il.com> wrote:
> > There are two ways to connect the Steam Controller: directly to the USB
> > or with the USB wireless adapter. Both methods are similar, but the
> > wireless adapter can connect up to 4 devices at the same time.
> >
> > The wired device will appear as 3 interfaces: a virtual mouse, a virtual
> > keyboard and a custom HID device.
> >
> > The wireless device will appear as 5 interfaces: a virtual keyboard and
> > 4 custom HID devices, that will remain silent until a device is actually
> > connected.
> >
> > The custom HID device has a report descriptor with all vendor specific
> > usages, so the hid-generic is not very useful. In a PC/SteamBox Valve
> > Steam Client provices a software translation by using direct USB access
> > and a creates a uinput virtual gamepad.
> >
> > This driver was reverse engineered to provide direct kernel support in
> > case you cannot, or do not want to, use Valve Steam Client. It disables
> > the virtual keyboard and mouse, as they are not so useful when you have
> > a working gamepad.
>
>
> > +// SPDX-License-Identifier: GPL-2.0
>
> > +MODULE_LICENSE("GPL");
>
> Not the same.
Hmmm... I copied from usb-skeleton.c, IIRC...
I'll change to GPL-2.0+, that would be correct, I think.
>
> > +static void steam_unregister(struct steam_device *steam)
> > +{
> > + struct input_dev *input;
> > +
> > + rcu_read_lock();
> > + input = rcu_dereference(steam->input);
> > + rcu_read_unlock();
> > +
>
> > + if (input) {
>
> if (!input)
> return;
>
> ?
That was because of symmetry, because further patches add more objects.
Then
if (input)
free(input);
if (battery)
free(battery);
/* in the future *(
if (input_gyro)
free(input_gyro);
Sure, the last one can do an early return, but you break symmetry.
>
> > + RCU_INIT_POINTER(steam->input, NULL);
> > + synchronize_rcu();
> > + hid_info(steam->hdev, "Steam Controller disconnected");
> > + input_unregister_device(input);
> > + }
> > +}
>
> > +static bool steam_is_valve_interface(struct hid_device *hdev)
> > +{
> > + struct hid_report_enum *rep_enum;
> > + struct hid_report *hreport;
> > +
> > + /*
> > + * The wired device creates 3 interfaces:
> > + * 0: emulated mouse.
> > + * 1: emulated keyboard.
> > + * 2: the real game pad.
> > + * The wireless device creates 5 interfaces:
> > + * 0: emulated keyboard.
> > + * 1-4: slots where up to 4 real game pads will be connected to.
> > + * We know which one is the real gamepad interface because they are the
> > + * only ones with a feature report.
> > + */
> > + rep_enum = &hdev->report_enum[HID_FEATURE_REPORT];
>
> > + list_for_each_entry(hreport, &rep_enum->report_list, list) {
> > + /* should we check hreport->id == 0? */
> > + return true;
> > + }
> > + return false;
>
> So, for now it's just an equivalent of
>
> return !list_empty();
>
> ?
I was expecting to add a few more checks in the middle, but those
weren't needed at the end.
I'll change that.
>
> > +}
>
> > + /*
> > + * From this point on, if anything fails return 0 and ignores
> > + * the error, so that the default HID devices are still bound.
> > + */
> > + steam = devm_kzalloc(&hdev->dev,
> > + sizeof(struct steam_device), GFP_KERNEL);
>
> sizeof(*steam) saves a line.
Right, changed.
>
> > + if (!steam) {
> > + ret = -ENOMEM;
> > + goto mem_fail;
> > + }
>
> > +static void steam_remove(struct hid_device *hdev)
> > +{
> > + struct steam_device *steam = hid_get_drvdata(hdev);
> > +
> > + if (steam && (steam->quirks & STEAM_QUIRK_WIRELESS)) {
> > + hid_info(hdev, "Steam wireless receiver disconnected");
> > + hid_hw_close(hdev);
> > + }
> > +
> > + hid_hw_stop(hdev);
> > +
> > + if (steam) {
> > + cancel_work_sync(&steam->work_connect);
> > + steam_unregister(steam);
>
> > + hid_set_drvdata(hdev, NULL);
>
> Hmm.. Doesn't HID do this?
Do you mean the hid_set_drvdata(hdev, NULL)? I'm not sure, I didn't see
that on hid-core.c or hid-generic.c. And a call like this is done in
many modules... so I did the same, just to be sure.
>
> > + }
>
> if (steam) {
> ...
> hid_hw_stop(hdev);
> ...
> } else {
> hid_hw_stop(hdev);
> }
>
> ?
I have no real preference. Your version has two 'if', mine has two 'if'.
What about:
static void steam_remove(struct hid_device *hdev)
{
struct steam_device *steam = hid_get_drvdata(hdev);
if (!steam) {
hid_hw_stop(hdev);
return;
}
if (steam->quirks & STEAM_QUIRK_WIRELESS) {
hid_info(hdev, "Steam wireless receiver disconnected");
hid_hw_close(hdev);
}
hid_hw_stop(hdev);
cancel_work_sync(&steam->work_connect);
steam_unregister(steam);
hid_set_drvdata(hdev, NULL);
}
>
> > +}
>
> > +static void steam_do_input_event(struct steam_device *steam,
> > + struct input_dev *input, u8 *data)
> > +{
> > + /* 24 bits of buttons */
> > + u8 b8, b9, b10;
> > + bool lpad_touched, lpad_and_joy;
> > +
> > + b8 = data[8];
> > + b9 = data[9];
> > + b10 = data[10];
> > +
> > + input_report_abs(input, ABS_Z, data[11]);
> > + input_report_abs(input, ABS_RZ, data[12]);
> > +
> > + /*
> > + * These two bits tells how to interpret the values X and Y.
> > + * lpad_and_joy tells that the joystick and the lpad are used at the
> > + * same time.
> > + * lpad_touched tells whether X/Y are to be read as lpad coord or
> > + * joystick values.
> > + * (lpad_touched || lpad_and_joy) tells if the lpad is really touched.
> > + */
>
> > + lpad_touched = b10 & 0x08;
>
> BIT(3) ?
>
> > + lpad_and_joy = b10 & 0x80;
>
> BIT(7) ?
>
> > + input_event(input, EV_KEY, BTN_TR2, !!(b8 & 0x01));
> > + input_event(input, EV_KEY, BTN_TL2, !!(b8 & 0x02));
> > + input_event(input, EV_KEY, BTN_TR, !!(b8 & 0x04));
> > + input_event(input, EV_KEY, BTN_TL, !!(b8 & 0x08));
> > + input_event(input, EV_KEY, BTN_Y, !!(b8 & 0x10));
> > + input_event(input, EV_KEY, BTN_B, !!(b8 & 0x20));
> > + input_event(input, EV_KEY, BTN_X, !!(b8 & 0x40));
> > + input_event(input, EV_KEY, BTN_A, !!(b8 & 0x80));
> > + input_event(input, EV_KEY, BTN_SELECT, !!(b9 & 0x10));
> > + input_event(input, EV_KEY, BTN_MODE, !!(b9 & 0x20));
> > + input_event(input, EV_KEY, BTN_START, !!(b9 & 0x40));
> > + input_event(input, EV_KEY, BTN_GEAR_DOWN, !!(b9 & 0x80));
> > + input_event(input, EV_KEY, BTN_GEAR_UP, !!(b10 & 0x01));
> > + input_event(input, EV_KEY, BTN_THUMBR, !!(b10 & 0x04));
> > + input_event(input, EV_KEY, BTN_THUMBL, !!(b10 & 0x40));
> > + input_event(input, EV_KEY, BTN_THUMB, lpad_touched || lpad_and_joy);
> > + input_event(input, EV_KEY, BTN_THUMB2, !!(b10 & 0x10));
>
> BIT(x) ?
>
> > +
> > + input_report_abs(input, ABS_HAT0X,
> > + !!(b9 & 0x02) - !!(b9 & 0x04));
> > + input_report_abs(input, ABS_HAT0Y,
> > + !!(b9 & 0x08) - !!(b9 & 0x01));
>
> BIT(x) ?
That's certainly nicer. Changed.
>
> > +}
>
> > +static int steam_raw_event(struct hid_device *hdev,
> > + struct hid_report *report, u8 *data,
> > + int size)
> > +{
> > + struct steam_device *steam = hid_get_drvdata(hdev);
> > + struct input_dev *input;
> > +
>
> > + if (!steam)
> > + return 0;
>
> When it's possible?
That's because how the new automatic unbinding/rebinding of hid-generic
works. This driver binds all the interfaces of the device, including the
virtual mouse and keyboard (!steam_is_valve_interface()). Those
hid_devices do not have a steam_device, but they still generate
raw_events.
>
> > + return 0;
> > +}
>
> --
> With Best Regards,
> Andy Shevchenko
Regards.
Rodrigo.
Powered by blists - more mailing lists