On September 10, 2020 12:40:59 PM GMT+09:00, James Hilliard <james.hilliard1@xxxxxxxxx> wrote:
>On Wed, Sep 9, 2020 at 9:02 PM Oliver Neukum <oneukum@xxxxxxx> wrote:
>>
>> Am Mittwoch, den 09.09.2020, 13:34 -0600 schrieb James Hilliard:
>> > This patch detects and reverses the effects of the malicious FTDI
>> > Windows driver version 2.12.00(FTDIgate).
>>
>> Hi,
>>
>> this raises questions.
>> Should we do this unconditionally without asking?
>Well I think since we can reliably detect devices that have been
>bricked by the malicious windows driver it's fine. I was careful to
>ensure that this will bail out and not try to change anything unless
>all
>conditions match this specific brick attack.
>> Does this belong into kernel space?
>This seemed to be by far the simplest option for embedded systems
>that need to automatically detect and repair the bricked eeproms.
>
>People seem to have plugged a bunch of counterfeit FTDI Arduino's
>that normally attach to an embedded Linux host into windows for
>some reason for a kiosk platform of mine which messed up the
>userspace detection/mappings. This seemed like the best way to
>avoid this being a support issue requiring manual unbricking
>prochedures.
If you need to update the kernel on this platform anyway to use this feature, why not just introduce a userspace script to fix the bricked units instead?
Needing this autofixed seems like somewhat of a niche use case better served by a script on platforms where it might be a problem, rather than upstream kernel code.
>>
>> > +static int ftdi_repair_brick(struct usb_serial_port *port)
>> > +{
>> > + struct ftdi_private *priv = usb_get_serial_port_data(port);
>> > + int orig_latency;
>> > + int rv;
>> > + u16 *eeprom_data;
>> > + u16 checksum;
>> > + int eeprom_size;
>> > + int result;
>> > +
>> > + switch (priv->chip_type) {
>> > + case FT232RL:
>> > + eeprom_size = 0x40;
>> > + break;
>> > + default:
>> > + /* Unsupported for brick repair */
>> > + return 0;
>> > + }
>> > +
>> > + /* Latency timer needs to be 0x77 to unlock EEPROM
>programming */
>> > + if (priv->latency != 0x77) {
>> > + orig_latency = priv->latency;
>> > + priv->latency = 0x77;
>> > + rv = write_latency_timer(port);
>> > + priv->latency = orig_latency;
>> > + if (rv < 0)
>> > + return -EIO;
>> > + }
>>
>> Do you really want to change this without returning to the original?
>> @@ -2255,6 +2364,12 @@ static int ftdi_sio_port_probe(struct
>usb_serial_port *port)
>> ftdi_set_max_packet_size(port);
>> if (read_latency_timer(port) < 0)
>> priv->latency = 16;
>> + vendor_id =
>le16_to_cpu(port->serial->dev->descriptor.idVendor);
>> + product_id =
>le16_to_cpu(port->serial->dev->descriptor.idProduct);
>> + if (vendor_id == FTDI_VID &&
>> + product_id == FTDI_BRICK_PID &&
>> + priv->chip_type == FT232RL)
>> + ftdi_repair_brick(port);
>> write_latency_timer(port);
>It should get restored here.
>> create_sysfs_attrs(port);
>>
>>
>> Regards
>> Oliver
>>
--
Hector Martin "marcan" (hector@xxxxxxxxxxxxxx)
Public key: https://mrcn.st/pub
