Add Makefile for installing a HID gadget

The Makefile has targets for building, installing and uninstalling a HID
gadget which acts as FIDO2 authenticator.

Tested on Ubuntu 18.04 but should work on other distros as well. The
only assumption being made is that kernel source is available at
/usr/src/linux-source-$(KERNEL_VERSION).tar.bz2. A possible improvement
would be to have a configure script which finds the correct kernel
source archive.

tools/gadgetfs/Makefile

@@ -0,0 +1,65 @@
+TOP := $(shell dirname $(realpath $(lastword $(MAKEFILE_LIST))))
+KERNEL_FULL_VERSION := $(shell uname -r)
+KERNEL_VERSION := $(shell uname -r | grep -o "^[^-]*")
+KERNEL_MAJOR := $(shell uname -r | cut -d. -f1)
+KERNEL_MINOR := $(shell uname -r | cut -d. -f2)
+
+MANUFACTURER = "Solo"
+SERIAL = "1234567890"
+IDVENDOR = "0x0483"
+IDPRODUCT = "0xa2ca"
+PRODUCT = "Solo Software Authenticator"
+CONFIGFS = /sys/kernel/config
+CONFIGFS_FIDO2 = $(CONFIGFS)/usb_gadget/fido2
+
+obj-m := dummy_hcd.o
+KVERSION := $(shell uname -r)
+SHELL := /bin/bash
+
+all: dummy_hcd.ko
+
+install: dummy_hcd.ko
+	modprobe libcomposite
+	insmod dummy_hcd.ko
+	mkdir -p $(CONFIGFS_FIDO2)
+	mkdir -p $(CONFIGFS_FIDO2)/configs/c.1
+	mkdir -p $(CONFIGFS_FIDO2)/functions/hid.usb0
+	echo 0 > $(CONFIGFS_FIDO2)/functions/hid.usb0/protocol
+	echo 0 > $(CONFIGFS_FIDO2)/functions/hid.usb0/subclass
+	echo 64 > $(CONFIGFS_FIDO2)/functions/hid.usb0/report_length
+	echo -ne "\x06\xd0\xf1\x09\x01\xa1\x01\x09\x20\x15\x00\x26\xff\x00\x75\x08\x95\x40\x81\x02\x09\x21\x15\x00\x26\xff\x00\x75\x08\x95\x40\x91\x02\xc0" > $(CONFIGFS_FIDO2)/functions/hid.usb0/report_desc
+	mkdir $(CONFIGFS_FIDO2)/strings/0x409
+	mkdir $(CONFIGFS_FIDO2)/configs/c.1/strings/0x409
+	echo $(IDPRODUCT) > $(CONFIGFS_FIDO2)/idProduct
+	echo $(IDVENDOR) > $(CONFIGFS_FIDO2)/idVendor
+	echo $(SERIAL) > $(CONFIGFS_FIDO2)/strings/0x409/serialnumber
+	echo $(MANUFACTURER) > $(CONFIGFS_FIDO2)/strings/0x409/manufacturer
+	echo $(PRODUCT) > $(CONFIGFS_FIDO2)/strings/0x409/product
+	echo "Configuration 1" > $(CONFIGFS_FIDO2)/configs/c.1/strings/0x409/configuration
+	echo 120 > $(CONFIGFS_FIDO2)/configs/c.1/MaxPower
+	ln -s $(CONFIGFS_FIDO2)/functions/hid.usb0 $(CONFIGFS_FIDO2)/configs/c.1
+	echo "dummy_udc.0" > $(CONFIGFS_FIDO2)/UDC
+
+uninstall:
+	echo "" > $(CONFIGFS_FIDO2)/UDC
+	rm $(CONFIGFS_FIDO2)/configs/c.1/hid.usb0
+	rmdir $(CONFIGFS_FIDO2)/configs/c.1/strings/0x409
+	rmdir $(CONFIGFS_FIDO2)/configs/c.1
+	rmdir $(CONFIGFS_FIDO2)/functions/hid.usb0
+	rmdir $(CONFIGFS_FIDO2)/strings/0x409
+	rmdir $(CONFIGFS_FIDO2)
+	rmmod dummy_hcd.ko
+
+dummy_hcd.ko: dummy_hcd.c
+	$(MAKE) -C /lib/modules/$(KERNEL_FULL_VERSION)/build M=$(TOP) modules
+
+dummy_hcd.c: /usr/src/linux-source-$(KERNEL_VERSION).tar.bz2
+	tar -xvf $^ linux-source-$(KERNEL_VERSION)/drivers/usb/gadget/udc/dummy_hcd.c
+	cp linux-source-$(KERNEL_VERSION)/drivers/usb/gadget/udc/dummy_hcd.c $@
+
+clean:
+	$(MAKE) -C /lib/modules/$(KERNEL_FULL_VERSION)/build M=$(TOP) clean
+	rm -rf linux-source-$(KERNEL_VERSION)
+	rm -f dummy_hcd.c
+
+