Hi everyone,
I’ve got a comment from Nick Kossifidis that I probably shouldn’t set
RNG’s quality to 1024. Adding linux-crypto@ to the loop.
On 23/10/2018 16:46, Andrej Shadura wrote:
> U2F Zero supports custom commands for blinking the LED and getting data
> from the internal hardware RNG. Expose the blinking function as a LED
> device, and the internal hardware RNG as an HWRNG so that it can be used
> to feed the enthropy pool.
>
> Signed-off-by: Andrej Shadura <andrew.shad...@collabora.co.uk>
> ---
> drivers/hid/Kconfig | 15 ++
> drivers/hid/Makefile | 1 +
> drivers/hid/hid-ids.h | 1 +
> drivers/hid/hid-u2fzero.c | 371 ++++++++++++++++++++++++++++++++++++++
> 4 files changed, 388 insertions(+)
> create mode 100644 drivers/hid/hid-u2fzero.c
>
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 61e1953ff921..3de6bf202f20 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -975,6 +975,21 @@ config HID_UDRAW_PS3
> Say Y here if you want to use the THQ uDraw gaming tablet for
> the PS3.
>
> +config HID_U2FZERO
> + tristate "U2F Zero LED and RNG support"
> + depends on HID
> + depends on LEDS_CLASS
> + help
> + Support for the LED of the U2F Zero device.
> +
> + U2F Zero supports custom commands for blinking the LED
> + and getting data from the internal hardware RNG.
> + The internal hardware can be used to feed the enthropy pool.
> +
> + U2F Zero only supports blinking its LED, so this driver doesn't
> + allow setting the brightness to anything but 1, which will
> + trigger a single blink and immediately reset to back 0.
> +
> config HID_WACOM
> tristate "Wacom Intuos/Graphire tablet support (USB)"
> depends on USB_HID
> diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> index bd7ac53b75c5..617b1a928b6a 100644
> --- a/drivers/hid/Makefile
> +++ b/drivers/hid/Makefile
> @@ -107,6 +107,7 @@ obj-$(CONFIG_HID_THRUSTMASTER) += hid-tmff.o
> obj-$(CONFIG_HID_TIVO) += hid-tivo.o
> obj-$(CONFIG_HID_TOPSEED) += hid-topseed.o
> obj-$(CONFIG_HID_TWINHAN) += hid-twinhan.o
> +obj-$(CONFIG_HID_U2FZERO) += hid-u2fzero.o
> obj-$(CONFIG_HID_UCLOGIC) += hid-uclogic.o
> obj-$(CONFIG_HID_UDRAW_PS3) += hid-udraw-ps3.o
> obj-$(CONFIG_HID_LED) += hid-led.o
> diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> index bc49909aba8e..070a2fcd8a18 100644
> --- a/drivers/hid/hid-ids.h
> +++ b/drivers/hid/hid-ids.h
> @@ -309,6 +309,7 @@
> #define USB_DEVICE_ID_CYGNAL_RADIO_SI470X 0x818a
> #define USB_DEVICE_ID_FOCALTECH_FTXXXX_MULTITOUCH 0x81b9
> #define USB_DEVICE_ID_CYGNAL_CP2112 0xea90
> +#define USB_DEVICE_ID_U2F_ZERO 0x8acf
>
> #define USB_DEVICE_ID_CYGNAL_RADIO_SI4713 0x8244
>
> diff --git a/drivers/hid/hid-u2fzero.c b/drivers/hid/hid-u2fzero.c
> new file mode 100644
> index 000000000000..bd4077c93c97
> --- /dev/null
> +++ b/drivers/hid/hid-u2fzero.c
> @@ -0,0 +1,371 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * U2F Zero LED and RNG driver
> + *
> + * Copyright 2018 Andrej Shadura <and...@shadura.me>
> + * Loosely based on drivers/hid/hid-led.c
> + * and drivers/usb/misc/chaoskey.c
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation, version 2.
> + */
> +
> +#include <linux/hid.h>
> +#include <linux/hidraw.h>
> +#include <linux/hw_random.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/usb.h>
> +
> +#include "usbhid/usbhid.h"
> +#include "hid-ids.h"
> +
> +#define DRIVER_SHORT "u2fzero"
> +
> +#define HID_REPORT_SIZE 64
> +
> +/* We only use broadcast (CID-less) messages */
> +#define CID_BROADCAST 0xffffffff
> +
> +struct u2f_hid_msg {
> + u32 cid;
> + union {
> + struct {
> + u8 cmd;
> + u8 bcnth;
> + u8 bcntl;
> + u8 data[HID_REPORT_SIZE - 7];
> + } init;
> + struct {
> + u8 seq;
> + u8 data[HID_REPORT_SIZE - 5];
> + } cont;
> + };
> +} __packed;
> +
> +struct u2f_hid_report {
> + u8 report_type;
> + struct u2f_hid_msg msg;
> +} __packed;
> +
> +#define U2F_HID_MSG_LEN(f) (size_t)(((f).init.bcnth << 8) + (f).init.bcntl)
> +
> +/* Custom extensions to the U2FHID protocol */
> +#define U2F_CUSTOM_GET_RNG 0x21
> +#define U2F_CUSTOM_WINK 0x24
> +
> +struct u2fzero_device {
> + struct hid_device *hdev;
> + struct urb *urb; /* URB for the RNG data */
> + struct led_classdev ldev; /* Embedded struct for led */
> + struct hwrng hwrng; /* Embedded struct for hwrng */
> + char *led_name;
> + char *rng_name;
> + u8 *buf_out;
> + u8 *buf_in;
> + struct mutex lock;
> + bool present;
> +};
> +
> +static int u2fzero_send(struct u2fzero_device *dev, struct u2f_hid_report
> *req)
> +{
> + int ret;
> +
> + mutex_lock(&dev->lock);
> +
> + memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
> +
> + ret = hid_hw_output_report(dev->hdev, dev->buf_out,
> + sizeof(struct u2f_hid_msg));
> +
> + mutex_unlock(&dev->lock);
> +
> + if (ret < 0)
> + return ret;
> +
> + return ret == sizeof(struct u2f_hid_msg) ? 0 : -EMSGSIZE;
> +}
> +
> +struct u2fzero_transfer_context {
> + struct completion done;
> + int status;
> +};
> +
> +static void u2fzero_read_callback(struct urb *urb)
> +{
> + struct u2fzero_transfer_context *ctx = urb->context;
> +
> + ctx->status = urb->status;
> + complete(&ctx->done);
> +}
> +
> +static int u2fzero_recv(struct u2fzero_device *dev,
> + struct u2f_hid_report *req,
> + struct u2f_hid_msg *resp)
> +{
> + int ret;
> + struct hid_device *hdev = dev->hdev;
> + struct u2fzero_transfer_context ctx;
> +
> + mutex_lock(&dev->lock);
> +
> + memcpy(dev->buf_out, req, sizeof(struct u2f_hid_report));
> +
> + dev->urb->context = &ctx;
> + init_completion(&ctx.done);
> +
> + ret = usb_submit_urb(dev->urb, GFP_NOIO);
> + if (unlikely(ret)) {
> + hid_err(hdev, "usb_submit_urb failed: %d", ret);
> + goto err;
> + }
> +
> + ret = hid_hw_output_report(dev->hdev, dev->buf_out,
> + sizeof(struct u2f_hid_msg));
> +
> + if (ret < 0) {
> + hid_err(hdev, "hid_hw_output_report failed: %d", ret);
> + goto err;
> + }
> +
> + ret = (wait_for_completion_timeout(
> + &ctx.done, msecs_to_jiffies(USB_CTRL_SET_TIMEOUT)));
> + if (ret < 0) {
> + usb_kill_urb(dev->urb);
> + hid_err(hdev, "urb submission timed out");
> + } else {
> + ret = dev->urb->actual_length;
> + memcpy(resp, dev->buf_in, ret);
> + }
> +
> +err:
> + mutex_unlock(&dev->lock);
> +
> + return ret;
> +}
> +
> +static int u2fzero_blink(struct led_classdev *ldev)
> +{
> + struct u2fzero_device *dev = container_of(ldev,
> + struct u2fzero_device, ldev);
> + struct u2f_hid_report req = {
> + .report_type = 0,
> + .msg.cid = CID_BROADCAST,
> + .msg.init = {
> + .cmd = U2F_CUSTOM_WINK,
> + .bcnth = 0,
> + .bcntl = 0,
> + .data = {0},
> + }
> + };
> + return u2fzero_send(dev, &req);
> +}
> +
> +static int u2fzero_brightness_set(struct led_classdev *ldev,
> + enum led_brightness brightness)
> +{
> + ldev->brightness = LED_OFF;
> + if (brightness)
> + return u2fzero_blink(ldev);
> + else
> + return 0;
> +}
> +
> +static int u2fzero_rng_read(struct hwrng *rng, void *data,
> + size_t max, bool wait)
> +{
> + struct u2fzero_device *dev = container_of(rng,
> + struct u2fzero_device, hwrng);
> + struct u2f_hid_report req = {
> + .report_type = 0,
> + .msg.cid = CID_BROADCAST,
> + .msg.init = {
> + .cmd = U2F_CUSTOM_GET_RNG,
> + .bcnth = 0,
> + .bcntl = 0,
> + .data = {0},
> + }
> + };
> + struct u2f_hid_msg resp;
> + int ret;
> + size_t actual_length;
> +
> + if (!dev->present) {
> + hid_dbg(dev->hdev, "device not present");
> + return 0;
> + }
> +
> + ret = u2fzero_recv(dev, &req, &resp);
> + if (ret < 0)
> + return 0;
> +
> + /* only take the minimum amount of data it is safe to take */
> + actual_length = min3((size_t)ret - offsetof(struct u2f_hid_msg,
> + init.data), U2F_HID_MSG_LEN(resp), max);
> +
> + memcpy(data, resp.init.data, actual_length);
> +
> + return actual_length;
> +}
> +
> +static int u2fzero_init_led(struct u2fzero_device *dev,
> + unsigned int minor)
> +{
> + dev->led_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
> + "%s%u", DRIVER_SHORT, minor);
> + if (dev->led_name == NULL)
> + return -ENOMEM;
> +
> + dev->ldev.name = dev->led_name;
> + dev->ldev.max_brightness = LED_ON;
> + dev->ldev.flags = LED_HW_PLUGGABLE;
> + dev->ldev.brightness_set_blocking = u2fzero_brightness_set;
> +
> + return devm_led_classdev_register(&dev->hdev->dev, &dev->ldev);
> +}
> +
> +static int u2fzero_init_hwrng(struct u2fzero_device *dev,
> + unsigned int minor)
> +{
> + dev->rng_name = devm_kasprintf(&dev->hdev->dev, GFP_KERNEL,
> + "%s-rng%u", DRIVER_SHORT, minor);
> + if (dev->rng_name == NULL)
> + return -ENOMEM;
> +
> + dev->hwrng.name = dev->rng_name;
> + dev->hwrng.read = u2fzero_rng_read;
> + dev->hwrng.quality = 1024;
> +
> + return devm_hwrng_register(&dev->hdev->dev, &dev->hwrng);
> +}
> +
> +static int u2fzero_fill_in_urb(struct u2fzero_device *dev)
> +{
> + struct hid_device *hdev = dev->hdev;
> + struct usb_device *udev;
> + struct usbhid_device *usbhid = hdev->driver_data;
> + unsigned int pipe_in;
> + struct usb_host_endpoint *ep;
> +
> + if (dev->hdev->bus != BUS_USB)
> + return -EINVAL;
> +
> + udev = hid_to_usb_dev(hdev);
> +
> + if (!usbhid->urbout || !usbhid->urbin)
> + return -ENODEV;
> +
> + ep = usb_pipe_endpoint(udev, usbhid->urbin->pipe);
> + if (!ep)
> + return -ENODEV;
> +
> + dev->urb = usb_alloc_urb(0, GFP_KERNEL);
> + if (!dev->urb)
> + return -ENOMEM;
> +
> + pipe_in = (usbhid->urbin->pipe & ~(3 << 30)) | (PIPE_INTERRUPT << 30);
> +
> + usb_fill_int_urb(dev->urb,
> + udev,
> + pipe_in,
> + dev->buf_in,
> + HID_REPORT_SIZE,
> + u2fzero_read_callback,
> + NULL,
> + ep->desc.bInterval);
> +
> + return 0;
> +}
> +
> +static int u2fzero_probe(struct hid_device *hdev,
> + const struct hid_device_id *id)
> +{
> + struct u2fzero_device *dev;
> + unsigned int minor;
> + int ret;
> +
> + dev = devm_kzalloc(&hdev->dev, sizeof(*dev), GFP_KERNEL);
> + if (dev == NULL)
> + return -ENOMEM;
> +
> + dev->buf_out = devm_kmalloc(&hdev->dev,
> + sizeof(struct u2f_hid_report), GFP_KERNEL);
> + if (dev->buf_out == NULL)
> + return -ENOMEM;
> +
> + dev->buf_in = devm_kmalloc(&hdev->dev,
> + sizeof(struct u2f_hid_msg), GFP_KERNEL);
> + if (dev->buf_in == NULL)
> + return -ENOMEM;
> +
> + ret = hid_parse(hdev);
> + if (ret)
> + return ret;
> +
> + dev->hdev = hdev;
> + hid_set_drvdata(hdev, dev);
> + mutex_init(&dev->lock);
> +
> + ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
> + if (ret)
> + return ret;
> +
> + u2fzero_fill_in_urb(dev);
> +
> + dev->present = true;
> +
> + minor = ((struct hidraw *) hdev->hidraw)->minor;
> +
> + ret = u2fzero_init_led(dev, minor);
> + if (ret) {
> + hid_hw_stop(hdev);
> + return ret;
> + }
> +
> + hid_info(hdev, "U2F Zero LED initialised\n");
> +
> + ret = u2fzero_init_hwrng(dev, minor);
> + if (ret) {
> + hid_hw_stop(hdev);
> + return ret;
> + }
> +
> + hid_info(hdev, "U2F Zero RNG initialised\n");
> +
> + return 0;
> +}
> +
> +static void u2fzero_remove(struct hid_device *hdev)
> +{
> + struct u2fzero_device *dev = hid_get_drvdata(hdev);
> +
> + mutex_lock(&dev->lock);
> + dev->present = false;
> + mutex_unlock(&dev->lock);
> +
> + hid_hw_stop(hdev);
> + usb_poison_urb(dev->urb);
> + usb_free_urb(dev->urb);
> +}
> +
> +static const struct hid_device_id u2fzero_table[] = {
> + { HID_USB_DEVICE(USB_VENDOR_ID_CYGNAL,
> + USB_DEVICE_ID_U2F_ZERO) },
> + { }
> +};
> +MODULE_DEVICE_TABLE(hid, u2fzero_table);
> +
> +static struct hid_driver u2fzero_driver = {
> + .name = "hid-" DRIVER_SHORT,
> + .probe = u2fzero_probe,
> + .remove = u2fzero_remove,
> + .id_table = u2fzero_table,
> +};
> +
> +module_hid_driver(u2fzero_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Andrej Shadura <and...@shadura.me>");
> +MODULE_DESCRIPTION("U2F Zero LED and RNG driver");
>
--
Cheers,
Andrej
