[PATCH v2 4/6] usb: Add environment based device blocklist

[Marek Vasut]

On 3/17/24 12:34 PM, Janne Grunau wrote:
> Hej,
> 
> On Sun, Mar 17, 2024, at 12:07, Janne Grunau via B4 Relay wrote:
>> From: Janne Grunau <j at jannau.net>
>>
>> Add the environment variable "usb_blocklist" to prevent USB devices
>> listed in it from being used. This allows to ignore devices which
>> trigger bugs in u-boot's USB stack or are undesirable for other reasons.
>> Devices emulating keyboards are one example. U-boot currently supports
>> only one USB keyboard device. Most commonly, people run into this with
>> Yubikeys, so let's ignore those in the default environment.
>>
>> Based on previous USB keyboard specific patches for the same purpose.
>>
>> Link:
>> https://lore.kernel.org/u-boot/7ab604fb-0fec-4f5e-8708-7a3a7e2cb568@denx.de/
>> Signed-off-by: Janne Grunau <j at jannau.net>
>> ---
>>   common/usb.c              | 56
>> +++++++++++++++++++++++++++++++++++++++++++++++
>>   doc/usage/environment.rst | 12 ++++++++++
>>   include/env_default.h     | 11 ++++++++++
>>   3 files changed, 79 insertions(+)
>>
>> diff --git a/common/usb.c b/common/usb.c
>> index 836506dcd9..73af5be066 100644
>> --- a/common/usb.c
>> +++ b/common/usb.c
>> @@ -1084,6 +1084,57 @@ static int usb_prepare_device(struct usb_device
>> *dev, int addr, bool do_read,
>>   	return 0;
>>   }
>>
>> +static int usb_blocklist_parse_error(const char *blocklist, size_t pos)
>> +{
>> +	printf("usb_blocklist parse error at char %zu in \"%s\"\n", pos,
>> +	       blocklist);
>> +	return 0;
>> +}
>> +
>> +static int usb_device_is_blocked(u16 id_vendor, u16 id_product)
>> +{
>> +	ulong vid, pid;
>> +	char *end;
>> +	const char *block_str = env_get("usb_blocklist");
>> +	const char *cur = block_str;
>> +
>> +	/* parse "usb_blocklist" strictly */
>> +	while (cur && cur[0] != '\0') {
>> +		vid = simple_strtoul(cur, &end, 0);
>> +		if (cur == end || end[0] != ':')
>> +			return usb_blocklist_parse_error(block_str,
>> +							 cur - block_str);
>> +
>> +		cur = end + 1;
>> +		pid = simple_strtoul(cur, &end, 0);
>> +		if (cur == end && end[0] != '*')
>> +			return usb_blocklist_parse_error(block_str,
>> +							 cur - block_str);
>> +
>> +		if (end[0] == '*') {
>> +			/* use out of range idProduct as wildcard indication */
>> +			pid = U16_MAX + 1;
>> +			end++;
>> +		}
>> +		if (end[0] != ',' && end[0] != '\0')
>> +			return usb_blocklist_parse_error(block_str,
>> +							 cur - block_str);
>> +
>> +		if (id_vendor == vid && (pid > U16_MAX || id_product == pid)) {
>> +			printf("Ignoring USB device 0x%x:0x%x\n",id_vendor,
>> +			      id_product);
> 
> this is a leftover from testing, already removed locally

You could turn this into dev_dbg()