[PATCH 4/6] usb: kbd: Ignore Yubikeys

[Marek Vasut]

On 2/26/24 9:47 PM, Mark Kettenis wrote:
>> Date: Sun, 25 Feb 2024 22:57:23 +0100
>> From: Marek Vasut <marex at denx.de>
>>
>> On 2/25/24 5:07 PM, Janne Grunau wrote:
>>> Hej,
>>>
>>> On Wed, Feb 21, 2024, at 13:41, Marek Vasut wrote:
>>>> On 2/21/24 08:25, Janne Grunau via B4 Relay wrote:
>>>>> From: Hector Martin <marcan at marcan.st>
>>>>>
>>>>> We currently only support one USB keyboard device, but some devices
>>>>> emulate keyboards for other purposes. Most commonly, people run into
>>>>> this with Yubikeys, so let's ignore those.
>>>>>
>>>>> Even if we end up supporting multiple keyboards in the future, it's
>>>>> safer to ignore known non-keyboard devices.
>>>>>
>>>>> Signed-off-by: Hector Martin <marcan at marcan.st>
>>>>> ---
>>>>>     common/usb_kbd.c | 19 +++++++++++++++++++
>>>>>     1 file changed, 19 insertions(+)
>>>>>
>>>>> diff --git a/common/usb_kbd.c b/common/usb_kbd.c
>>>>> index 4cbc9acb73..774d3555d9 100644
>>>>> --- a/common/usb_kbd.c
>>>>> +++ b/common/usb_kbd.c
>>>>> @@ -120,6 +120,15 @@ struct usb_kbd_pdata {
>>>>>     
>>>>>     extern int __maybe_unused net_busy_flag;
>>>>>     
>>>>> +/*
>>>>> + * Since we only support one usbkbd device in the iomux,
>>>>> + * ignore common keyboard-emulating devices that aren't
>>>>> + * real keyboards.
>>>>> + */
>>>>> +const uint16_t vid_blocklist[] = {
>>>>> +	0x1050, /* Yubico */
>>>>> +};
>>>>> +
>>>>>     /* The period of time between two calls of usb_kbd_testc(). */
>>>>>     static unsigned long kbd_testc_tms;
>>>>>     
>>>>> @@ -465,6 +474,7 @@ static int usb_kbd_probe_dev(struct usb_device *dev, unsigned int ifnum)
>>>>>     	struct usb_endpoint_descriptor *ep;
>>>>>     	struct usb_kbd_pdata *data;
>>>>>     	int epNum;
>>>>> +	int i;
>>>>>     
>>>>>     	if (dev->descriptor.bNumConfigurations != 1)
>>>>>     		return 0;
>>>>> @@ -480,6 +490,15 @@ static int usb_kbd_probe_dev(struct usb_device *dev, unsigned int ifnum)
>>>>>     	if (iface->desc.bInterfaceProtocol != USB_PROT_HID_KEYBOARD)
>>>>>     		return 0;
>>>>>     
>>>>> +	for (i = 0; i < ARRAY_SIZE(vid_blocklist); i++) {
>>>>> +		if (dev->descriptor.idVendor == vid_blocklist[i]) {
>>>>> +			printf("Ignoring keyboard device 0x%x:0x%x\n",
>>>>> +			       dev->descriptor.idVendor,
>>>>> +			       dev->descriptor.idProduct);
>>>>> +			return 0;
>>>>> +		}
>>>>> +	}
>>>>
>>>> I vaguely recall a discussion about previous version of this, I think
>>>> the suggestion was to make the list of ignored devices configurable via
>>>> environment variable, so users can add to that list from U-Boot shell.
>>>> Would it be possible to make it work this way ?
>>>
>>> oh, I completely forgot that this patch was already submitted. I briefly looked through asahi tree for related patches and did not check whether this was previously submitted.
>>> I've added environment based blocking as separate patch with blocking either complete vendor IDs or vendor, product ID combinations. A separate patch to simplify authorship tracking and the implementation doesn't share any code.
>>
>> It would be better to have only one patch which does not hard-code any
>> USB IDs, and then add those blocked IDs via U-Boot default environment
>> for this specific machine. We cannot predict what yubico will do in the
>> future, whether they might make a device that shouldn't be blocked for
>> example. If they do, the user should be able to unblock their device by
>> running e.g. '=> setenv usb_blocklist' instead of updating their bootloader.
>>
>> I think a simple list of blocked VID:PID pairs, maybe with wildcards,
>> would be nice, i.e. something like 'usb_blocklist=1234:5678,1050:*' to
>> block device 0x1234:0x5678 and all devices with VID 0x1050 . That should
>> be easy to parse with strtok()/strtol() or some such and the code should
>> not be too complex.
> 
> I do like the idea of having a configurable list of usb devices to
> ignore.  The U-Boot USB stack is still not perfect

Very far from perfect, yes.

> and there are still
> USB devices that will prevent us from booting when connected.  The
> list will provide a nice workaround for that issue.
> 
> But the yubikeys will cause the same problem on other boards as well.
> So I think it makes sense to put those in a default list.

I agree.