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

[Janne Grunau]

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

Janne