text: // Copyright 2019 syzkaller project authors. All rights reserved.
  // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
  
  // This file is shared between executor and csource package.
  
  // Implementation of syz_usb_* pseudo-syscalls.
  
  #define USB_DEBUG 0
  
  #define USB_MAX_IFACE_NUM 4
  #define USB_MAX_EP_NUM 32
  
  struct usb_iface_index {
  	struct usb_interface_descriptor* iface;
  	uint8 bInterfaceNumber;
  	uint8 bAlternateSetting;
  	struct usb_endpoint_descriptor eps[USB_MAX_EP_NUM];
  	int eps_num;
  };
  
  struct usb_device_index {
  	struct usb_device_descriptor* dev;
  	struct usb_config_descriptor* config;
  	uint8 bMaxPower;
  	int config_length;
  	struct usb_iface_index ifaces[USB_MAX_IFACE_NUM];
  	int ifaces_num;
  	int iface_cur;
  };
  
  static bool parse_usb_descriptor(char* buffer, size_t length, struct usb_device_index* index)
  {
  	if (length < sizeof(*index->dev) + sizeof(*index->config))
  		return false;
  
  	memset(index, 0, sizeof(*index));
  
  	index->dev = (struct usb_device_descriptor*)buffer;
  	index->config = (struct usb_config_descriptor*)(buffer + sizeof(*index->dev));
  	index->bMaxPower = index->config->bMaxPower;
  	index->config_length = length - sizeof(*index->dev);
  	index->iface_cur = -1;
  	size_t offset = 0;
  
  	while (true) {
  		if (offset + 1 >= length)
  			break;
  		uint8 desc_length = buffer[offset];
  		uint8 desc_type = buffer[offset + 1];
  		if (desc_length <= 2)
  			break;
  		if (offset + desc_length > length)
  			break;
  		if (desc_type == USB_DT_INTERFACE && index->ifaces_num < USB_MAX_IFACE_NUM) {
  			struct usb_interface_descriptor* iface = (struct usb_interface_descriptor*)(buffer + offset);
  			debug("parse_usb_descriptor: found interface #%u (%d, %d) at %p\n",
  			      index->ifaces_num, iface->bInterfaceNumber, iface->bAlternateSetting, iface);
  			index->ifaces[index->ifaces_num].iface = iface;
  			index->ifaces[index->ifaces_num].bInterfaceNumber = iface->bInterfaceNumber;
  			index->ifaces[index->ifaces_num].bAlternateSetting = iface->bAlternateSetting;
  			index->ifaces_num++;
  		}
  		if (desc_type == USB_DT_ENDPOINT && index->ifaces_num > 0) {
  			struct usb_iface_index* iface = &index->ifaces[index->ifaces_num - 1];
  			debug("parse_usb_descriptor: found endpoint #%u at %p\n", iface->eps_num, buffer + offset);
  			if (iface->eps_num < USB_MAX_EP_NUM) {
  				memcpy(&iface->eps[iface->eps_num], buffer + offset, sizeof(iface->eps[iface->eps_num]));
  				iface->eps_num++;
  			}
  		}
  		offset += desc_length;
  	}
  
  	return true;
  }
  
  struct usb_raw_init {
  	__u64 speed;
  	const __u8* driver_name;
  	const __u8* device_name;
  };
  
  enum usb_raw_event_type {
  	USB_RAW_EVENT_INVALID,
  	USB_RAW_EVENT_CONNECT,
  	USB_RAW_EVENT_CONTROL,
  };
  
  struct usb_raw_event {
  	__u32 type;
  	__u32 length;
  	__u8 data[0];
  };
  
  struct usb_raw_ep_io {
  	__u16 ep;
  	__u16 flags;
  	__u32 length;
  	__u8 data[0];
  };
  
  #define USB_RAW_IOCTL_INIT _IOW('U', 0, struct usb_raw_init)
  #define USB_RAW_IOCTL_RUN _IO('U', 1)
  #define USB_RAW_IOCTL_EVENT_FETCH _IOR('U', 2, struct usb_raw_event)
  #define USB_RAW_IOCTL_EP0_WRITE _IOW('U', 3, struct usb_raw_ep_io)
  #define USB_RAW_IOCTL_EP0_READ _IOWR('U', 4, struct usb_raw_ep_io)
  #define USB_RAW_IOCTL_EP_ENABLE _IOW('U', 5, struct usb_endpoint_descriptor)
  #define USB_RAW_IOCTL_EP_DISABLE _IOW('U', 6, __u32)
  #define USB_RAW_IOCTL_EP_WRITE _IOW('U', 7, struct usb_raw_ep_io)
  #define USB_RAW_IOCTL_EP_READ _IOWR('U', 8, struct usb_raw_ep_io)
  #define USB_RAW_IOCTL_CONFIGURE _IO('U', 9)
  #define USB_RAW_IOCTL_VBUS_DRAW _IOW('U', 10, __u32)
  
  static int usb_raw_open()
  {
  	return open("/dev/raw-gadget", O_RDWR);
  }
  
  static int usb_raw_init(int fd, uint32 speed, const char* driver, const char* device)
  {
  	struct usb_raw_init arg;
  	arg.speed = speed;
  	arg.driver_name = (const __u8*)driver;
  	arg.device_name = (const __u8*)device;
  	return ioctl(fd, USB_RAW_IOCTL_INIT, &arg);
  }
  
  static int usb_raw_run(int fd)
  {
  	return ioctl(fd, USB_RAW_IOCTL_RUN, 0);
  }
  
  static int usb_raw_event_fetch(int fd, struct usb_raw_event* event)
  {
  	return ioctl(fd, USB_RAW_IOCTL_EVENT_FETCH, event);
  }
  
  static int usb_raw_ep0_write(int fd, struct usb_raw_ep_io* io)
  {
  	return ioctl(fd, USB_RAW_IOCTL_EP0_WRITE, io);
  }
  
  static int usb_raw_ep0_read(int fd, struct usb_raw_ep_io* io)
  {
  	return ioctl(fd, USB_RAW_IOCTL_EP0_READ, io);
  }
  
  #if SYZ_EXECUTOR || __NR_syz_usb_ep_write
  static int usb_raw_ep_write(int fd, struct usb_raw_ep_io* io)
  {
  	return ioctl(fd, USB_RAW_IOCTL_EP_WRITE, io);
  }
  #endif
  
  #if SYZ_EXECUTOR || __NR_syz_usb_ep_read
  static int usb_raw_ep_read(int fd, struct usb_raw_ep_io* io)
  {
  	return ioctl(fd, USB_RAW_IOCTL_EP_READ, io);
  }
  #endif
  
  static int usb_raw_ep_enable(int fd, struct usb_endpoint_descriptor* desc)
  {
  	return ioctl(fd, USB_RAW_IOCTL_EP_ENABLE, desc);
  }
  
  static int usb_raw_ep_disable(int fd, int ep)
  {
  	return ioctl(fd, USB_RAW_IOCTL_EP_DISABLE, ep);
  }
  
  static int usb_raw_configure(int fd)
  {
  	return ioctl(fd, USB_RAW_IOCTL_CONFIGURE, 0);
  }
  
  static int usb_raw_vbus_draw(int fd, uint32 power)
  {
  	return ioctl(fd, USB_RAW_IOCTL_VBUS_DRAW, power);
  }
  
  #define MAX_USB_FDS 6
  
  struct usb_info {
  	int fd;
  	struct usb_device_index index;
  };
  
  static struct usb_info usb_devices[MAX_USB_FDS];
  static int usb_devices_num;
  
  static struct usb_device_index* add_usb_index(int fd, char* dev, size_t dev_len)
  {
  	int i = __atomic_fetch_add(&usb_devices_num, 1, __ATOMIC_RELAXED);
  	if (i >= MAX_USB_FDS)
  		return NULL;
  
  	int rv = 0;
  	NONFAILING(rv = parse_usb_descriptor(dev, dev_len, &usb_devices[i].index));
  	if (!rv)
  		return NULL;
  
  	__atomic_store_n(&usb_devices[i].fd, fd, __ATOMIC_RELEASE);
  	return &usb_devices[i].index;
  }
  
  static struct usb_device_index* lookup_usb_index(int fd)
  {
  	int i;
  	for (i = 0; i < MAX_USB_FDS; i++) {
  		if (__atomic_load_n(&usb_devices[i].fd, __ATOMIC_ACQUIRE) == fd) {
  			return &usb_devices[i].index;
  		}
  	}
  	return NULL;
  }
  
  #if SYZ_EXECUTOR || __NR_syz_usb_control_io
  static int lookup_interface(int fd, uint8 bInterfaceNumber, uint8 bAlternateSetting)
  {
  	struct usb_device_index* index = lookup_usb_index(fd);
  	int i;
  
  	if (!index)
  		return -1;
  
  	for (i = 0; i < index->ifaces_num; i++) {
  		if (index->ifaces[i].bInterfaceNumber == bInterfaceNumber &&
  		    index->ifaces[i].bAlternateSetting == bAlternateSetting)
  			return i;
  	}
  	return -1;
  }
  #endif
  
  static void set_interface(int fd, int n)
  {
  	struct usb_device_index* index = lookup_usb_index(fd);
  	int ep;
  
  	if (!index)
  		return;
  
  	if (index->iface_cur >= 0 && index->iface_cur < index->ifaces_num) {
  		for (ep = 0; ep < index->ifaces[index->iface_cur].eps_num; ep++) {
  			int rv = usb_raw_ep_disable(fd, ep);
  			if (rv < 0) {
  				debug("set_interface: failed to disable endpoint %d\n", ep);
  			} else {
  				debug("set_interface: endpoint %d disabled\n", ep);
  			}
  		}
  	}
  	if (n >= 0 && n < index->ifaces_num) {
  		for (ep = 0; ep < index->ifaces[n].eps_num; ep++) {
  			int rv = usb_raw_ep_enable(fd, &index->ifaces[n].eps[ep]);
  			if (rv < 0) {
  				debug("set_interface: failed to enable endpoint %d\n", ep);
  			} else {
  				debug("set_interface: endpoint %d enabled as %d\n", ep, rv);
  			}
  		}
  		index->iface_cur = n;
  	}
  }
  
  static int configure_device(int fd)
  {
  	struct usb_device_index* index = lookup_usb_index(fd);
  
  	if (!index)
  		return -1;
  
  	int rv = usb_raw_vbus_draw(fd, index->bMaxPower);
  	if (rv < 0) {
  		debug("configure_device: usb_raw_vbus_draw failed with %d\n", rv);
  		return rv;
  	}
  	rv = usb_raw_configure(fd);
  	if (rv < 0) {
  		debug("configure_device: usb_raw_configure failed with %d\n", rv);
  		return rv;
  	}
  	set_interface(fd, 0);
  	return 0;
  }
  
  #define USB_MAX_PACKET_SIZE 1024
  
  struct usb_raw_control_event {
  	struct usb_raw_event inner;
  	struct usb_ctrlrequest ctrl;
  	char data[USB_MAX_PACKET_SIZE];
  };
  
  struct usb_raw_ep_io_data {
  	struct usb_raw_ep_io inner;
  	char data[USB_MAX_PACKET_SIZE];
  };
  
  struct vusb_connect_string_descriptor {
  	uint32 len;
  	char* str;
  } __attribute__((packed));
  
  struct vusb_connect_descriptors {
  	uint32 qual_len;
  	char* qual;
  	uint32 bos_len;
  	char* bos;
  	uint32 strs_len;
  	struct vusb_connect_string_descriptor strs[0];
  } __attribute__((packed));
  
  static const char default_string[] = {
      8, USB_DT_STRING,
      's', 0, 'y', 0, 'z', 0 // UTF16-encoded "syz"
  };
  
  static const char default_lang_id[] = {
      4, USB_DT_STRING,
      0x09, 0x04 // English (United States)
  };
  
  static bool lookup_connect_response(int fd, struct vusb_connect_descriptors* descs, struct usb_ctrlrequest* ctrl,
  				    char** response_data, uint32* response_length)
  {
  	struct usb_device_index* index = lookup_usb_index(fd);
  	uint8 str_idx;
  
  	if (!index)
  		return false;
  
  	switch (ctrl->bRequestType & USB_TYPE_MASK) {
  	case USB_TYPE_STANDARD:
  		switch (ctrl->bRequest) {
  		case USB_REQ_GET_DESCRIPTOR:
  			switch (ctrl->wValue >> 8) {
  			case USB_DT_DEVICE:
  				*response_data = (char*)index->dev;
  				*response_length = sizeof(*index->dev);
  				return true;
  			case USB_DT_CONFIG:
  				*response_data = (char*)index->config;
  				*response_length = index->config_length;
  				return true;
  			case USB_DT_STRING:
  				str_idx = (uint8)ctrl->wValue;
  				if (descs && str_idx < descs->strs_len) {
  					*response_data = descs->strs[str_idx].str;
  					*response_length = descs->strs[str_idx].len;
  					return true;
  				}
  				if (str_idx == 0) {
  					*response_data = (char*)&default_lang_id[0];
  					*response_length = default_lang_id[0];
  					return true;
  				}
  				*response_data = (char*)&default_string[0];
  				*response_length = default_string[0];
  				return true;
  			case USB_DT_BOS:
  				*response_data = descs->bos;
  				*response_length = descs->bos_len;
  				return true;
  			case USB_DT_DEVICE_QUALIFIER:
  				if (!descs->qual) {
  					// Fill in DEVICE_QUALIFIER based on DEVICE if not provided.
  					struct usb_qualifier_descriptor* qual =
  					    (struct usb_qualifier_descriptor*)response_data;
  					qual->bLength = sizeof(*qual);
  					qual->bDescriptorType = USB_DT_DEVICE_QUALIFIER;
  					qual->bcdUSB = index->dev->bcdUSB;
  					qual->bDeviceClass = index->dev->bDeviceClass;
  					qual->bDeviceSubClass = index->dev->bDeviceSubClass;
  					qual->bDeviceProtocol = index->dev->bDeviceProtocol;
  					qual->bMaxPacketSize0 = index->dev->bMaxPacketSize0;
  					qual->bNumConfigurations = index->dev->bNumConfigurations;
  					qual->bRESERVED = 0;
  					*response_length = sizeof(*qual);
  					return true;
  				}
  				*response_data = descs->qual;
  				*response_length = descs->qual_len;
  				return true;
  			default:
  				fail("lookup_connect_response: no response");
  				return false;
  			}
  			break;
  		default:
  			fail("lookup_connect_response: no response");
  			return false;
  		}
  		break;
  	default:
  		fail("lookup_connect_response: no response");
  		return false;
  	}
  
  	return false;
  }
  
  static volatile long syz_usb_connect(volatile long a0, volatile long a1, volatile long a2, volatile long a3)
  {
  	uint64 speed = a0;
  	uint64 dev_len = a1;
  	char* dev = (char*)a2;
  	struct vusb_connect_descriptors* descs = (struct vusb_connect_descriptors*)a3;
  
  	debug("syz_usb_connect: dev: %p\n", dev);
  	if (!dev) {
  		debug("syz_usb_connect: dev is null\n");
  		return -1;
  	}
  
  	debug("syz_usb_connect: device data:\n");
  	debug_dump_data(dev, dev_len);
  
  	int fd = usb_raw_open();
  	if (fd < 0) {
  		debug("syz_usb_connect: usb_raw_open failed with %d\n", fd);
  		return fd;
  	}
  	if (fd >= MAX_FDS) {
  		close(fd);
  		debug("syz_usb_connect: too many open fds\n");
  		return -1;
  	}
  	debug("syz_usb_connect: usb_raw_open success\n");
  
  	struct usb_device_index* index = add_usb_index(fd, dev, dev_len);
  	if (!index) {
  		debug("syz_usb_connect: add_usb_index failed\n");
  		return -1;
  	}
  	debug("syz_usb_connect: add_usb_index success\n");
  
  	// TODO: consider creating two dummy_udc's per proc to increace the chance of
  	// triggering interaction between multiple USB devices within the same program.
  	char device[32];
  	sprintf(&device[0], "dummy_udc.%llu", procid);
  	int rv = usb_raw_init(fd, speed, "dummy_udc", &device[0]);
  	if (rv < 0) {
  		debug("syz_usb_connect: usb_raw_init failed with %d\n", rv);
  		return rv;
  	}
  	debug("syz_usb_connect: usb_raw_init success\n");
  
  	rv = usb_raw_run(fd);
  	if (rv < 0) {
  		debug("syz_usb_connect: usb_raw_run failed with %d\n", rv);
  		return rv;
  	}
  	debug("syz_usb_connect: usb_raw_run success\n");
  
  	bool done = false;
  	while (!done) {
  		struct usb_raw_control_event event;
  		event.inner.type = 0;
  		event.inner.length = sizeof(event.ctrl);
  		rv = usb_raw_event_fetch(fd, (struct usb_raw_event*)&event);
  		if (rv < 0) {
  			debug("syz_usb_connect: usb_raw_event_fetch failed with %d\n", rv);
  			return rv;
  		}
  		if (event.inner.type != USB_RAW_EVENT_CONTROL)
  			continue;
  
  		debug("syz_usb_connect: bReqType: 0x%x (%s), bReq: 0x%x, wVal: 0x%x, wIdx: 0x%x, wLen: %d\n",
  		      event.ctrl.bRequestType, (event.ctrl.bRequestType & USB_DIR_IN) ? "IN" : "OUT",
  		      event.ctrl.bRequest, event.ctrl.wValue, event.ctrl.wIndex, event.ctrl.wLength);
  
  		bool response_found = false;
  		char* response_data = NULL;
  		uint32 response_length = 0;
  
  		if (event.ctrl.bRequestType & USB_DIR_IN) {
  			NONFAILING(response_found = lookup_connect_response(fd, descs, &event.ctrl, &response_data, &response_length));
  			if (!response_found) {
  				debug("syz_usb_connect: unknown control IN request\n");
  				return -1;
  			}
  		} else {
  			if ((event.ctrl.bRequestType & USB_TYPE_MASK) != USB_TYPE_STANDARD ||
  			    event.ctrl.bRequest != USB_REQ_SET_CONFIGURATION) {
  				fail("syz_usb_connect: unknown control OUT request");
  				return -1;
  			}
  			done = true;
  		}
  
  		if (done) {
  			rv = configure_device(fd);
  			if (rv < 0) {
  				debug("syz_usb_connect: configure_device failed with %d\n", rv);
  				return rv;
  			}
  		}
  
  		struct usb_raw_ep_io_data response;
  		response.inner.ep = 0;
  		response.inner.flags = 0;
  		if (response_length > sizeof(response.data))
  			response_length = 0;
  		if (event.ctrl.wLength < response_length)
  			response_length = event.ctrl.wLength;
  		response.inner.length = response_length;
  		if (response_data)
  			memcpy(&response.data[0], response_data, response_length);
  		else
  			memset(&response.data[0], 0, response_length);
  
  		if (event.ctrl.bRequestType & USB_DIR_IN) {
  			debug("syz_usb_connect: writing %d bytes\n", response.inner.length);
  			rv = usb_raw_ep0_write(fd, (struct usb_raw_ep_io*)&response);
  		} else {
  			rv = usb_raw_ep0_read(fd, (struct usb_raw_ep_io*)&response);
  			debug("syz_usb_connect: read %d bytes\n", response.inner.length);
  			debug_dump_data(&event.data[0], response.inner.length);
  		}
  		if (rv < 0) {
  			debug("syz_usb_connect: usb_raw_ep0_read/write failed with %d\n", rv);
  			return rv;
  		}
  	}
  
  	sleep_ms(200);
  
  	debug("syz_usb_connect: configured\n");
  
  	return fd;
  }
  
  #if SYZ_EXECUTOR || __NR_syz_usb_control_io
  struct vusb_descriptor {
  	uint8 req_type;
  	uint8 desc_type;
  	uint32 len;
  	char data[0];
  } __attribute__((packed));
  
  struct vusb_descriptors {
  	uint32 len;
  	struct vusb_descriptor* generic;
  	struct vusb_descriptor* descs[0];
  } __attribute__((packed));
  
  struct vusb_response {
  	uint8 type;
  	uint8 req;
  	uint32 len;
  	char data[0];
  } __attribute__((packed));
  
  struct vusb_responses {
  	uint32 len;
  	struct vusb_response* generic;
  	struct vusb_response* resps[0];
  } __attribute__((packed));
  
  static bool lookup_control_response(struct vusb_descriptors* descs, struct vusb_responses* resps,
  				    struct usb_ctrlrequest* ctrl, char** response_data, uint32* response_length)
  {
  	int descs_num = 0;
  	int resps_num = 0;
  
  	if (descs)
  		descs_num = (descs->len - offsetof(struct vusb_descriptors, descs)) / sizeof(descs->descs[0]);
  	if (resps)
  		resps_num = (resps->len - offsetof(struct vusb_responses, resps)) / sizeof(resps->resps[0]);
  
  	uint8 req = ctrl->bRequest;
  	uint8 req_type = ctrl->bRequestType & USB_TYPE_MASK;
  	uint8 desc_type = ctrl->wValue >> 8;
  
  	if (req == USB_REQ_GET_DESCRIPTOR) {
  		int i;
  
  		for (i = 0; i < descs_num; i++) {
  			struct vusb_descriptor* desc = descs->descs[i];
  			if (!desc)
  				continue;
  			if (desc->req_type == req_type && desc->desc_type == desc_type) {
  				*response_length = desc->len;
  				if (*response_length != 0)
  					*response_data = &desc->data[0];
  				else
  					*response_data = NULL;
  				return true;
  			}
  		}
  
  		if (descs && descs->generic) {
  			*response_data = &descs->generic->data[0];
  			*response_length = descs->generic->len;
  			return true;
  		}
  	} else {
  		int i;
  
  		for (i = 0; i < resps_num; i++) {
  			struct vusb_response* resp = resps->resps[i];
  			if (!resp)
  				continue;
  			if (resp->type == req_type && resp->req == req) {
  				*response_length = resp->len;
  				if (*response_length != 0)
  					*response_data = &resp->data[0];
  				else
  					*response_data = NULL;
  				return true;
  			}
  		}
  
  		if (resps && resps->generic) {
  			*response_data = &resps->generic->data[0];
  			*response_length = resps->generic->len;
  			return true;
  		}
  	}
  
  	return false;
  }
  
  #if USB_DEBUG
  #include <linux/hid.h>
  #include <linux/usb/cdc.h>
  #include <linux/usb/ch11.h>
  #include <linux/usb/ch9.h>
  
  static void analyze_control_request(struct usb_ctrlrequest* ctrl)
  {
  	switch (ctrl->bRequestType & USB_TYPE_MASK) {
  	case USB_TYPE_STANDARD:
  		switch (ctrl->bRequest) {
  		case USB_REQ_GET_DESCRIPTOR:
  			switch (ctrl->wValue >> 8) {
  			case USB_DT_DEVICE:
  			case USB_DT_CONFIG:
  			case USB_DT_STRING:
  			case HID_DT_REPORT:
  			case USB_DT_BOS:
  			case USB_DT_HUB:
  			case USB_DT_SS_HUB:
  				return;
  			}
  		}
  		break;
  	case USB_TYPE_CLASS:
  		switch (ctrl->bRequest) {
  		case USB_REQ_GET_INTERFACE:
  		case USB_REQ_GET_CONFIGURATION:
  		case USB_REQ_GET_STATUS:
  		case USB_CDC_GET_NTB_PARAMETERS:
  			return;
  		}
  	}
  	fail("analyze_control_request: unknown control request (0x%x, 0x%x, 0x%x)",
  	     ctrl->bRequestType, ctrl->bRequest, ctrl->wValue);
  }
  #endif
  
  static volatile long syz_usb_control_io(volatile long a0, volatile long a1, volatile long a2)
  {
  	int fd = a0;
  	struct vusb_descriptors* descs = (struct vusb_descriptors*)a1;
  	struct vusb_responses* resps = (struct vusb_responses*)a2;
  
  	struct usb_raw_control_event event;
  	event.inner.type = 0;
  	event.inner.length = USB_MAX_PACKET_SIZE;
  	int rv = usb_raw_event_fetch(fd, (struct usb_raw_event*)&event);
  	if (rv < 0) {
  		debug("syz_usb_control_io: usb_raw_ep0_read failed with %d\n", rv);
  		return rv;
  	}
  	if (event.inner.type != USB_RAW_EVENT_CONTROL) {
  		debug("syz_usb_control_io: wrong event type: %d\n", (int)event.inner.type);
  		return -1;
  	}
  
  	debug("syz_usb_control_io: bReqType: 0x%x (%s), bReq: 0x%x, wVal: 0x%x, wIdx: 0x%x, wLen: %d\n",
  	      event.ctrl.bRequestType, (event.ctrl.bRequestType & USB_DIR_IN) ? "IN" : "OUT",
  	      event.ctrl.bRequest, event.ctrl.wValue, event.ctrl.wIndex, event.ctrl.wLength);
  
  	bool response_found = false;
  	char* response_data = NULL;
  	uint32 response_length = 0;
  
  	if ((event.ctrl.bRequestType & USB_DIR_IN) && event.ctrl.wLength) {
  		NONFAILING(response_found = lookup_control_response(descs, resps, &event.ctrl, &response_data, &response_length));
  		if (!response_found) {
  #if USB_DEBUG
  			analyze_control_request(&event.ctrl);
  #endif
  			debug("syz_usb_control_io: unknown control IN request\n");
  			return -1;
  		}
  	} else {
  		if ((event.ctrl.bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD ||
  		    event.ctrl.bRequest == USB_REQ_SET_INTERFACE) {
  			int iface_num = event.ctrl.wIndex;
  			int alt_set = event.ctrl.wValue;
  			debug("syz_usb_control_io: setting interface (%d, %d)\n", iface_num, alt_set);
  			int iface_index = lookup_interface(fd, iface_num, alt_set);
  			if (iface_index < 0) {
  				debug("syz_usb_control_io: interface (%d, %d) not found\n", iface_num, alt_set);
  			} else {
  				set_interface(fd, iface_index);
  				debug("syz_usb_control_io: interface (%d, %d) set\n", iface_num, alt_set);
  			}
  		}
  
  		response_length = event.ctrl.wLength;
  	}
  
  	struct usb_raw_ep_io_data response;
  	response.inner.ep = 0;
  	response.inner.flags = 0;
  	if (response_length > sizeof(response.data))
  		response_length = 0;
  	if (event.ctrl.wLength < response_length)
  		response_length = event.ctrl.wLength;
  	if ((event.ctrl.bRequestType & USB_DIR_IN) && !event.ctrl.wLength) {
  		// Something fishy is going on, try to read more data.
  		response_length = USB_MAX_PACKET_SIZE;
  	}
  	response.inner.length = response_length;
  	if (response_data)
  		memcpy(&response.data[0], response_data, response_length);
  	else
  		memset(&response.data[0], 0, response_length);
  
  	if ((event.ctrl.bRequestType & USB_DIR_IN) && event.ctrl.wLength) {
  		debug("syz_usb_control_io: writing %d bytes\n", response.inner.length);
  		debug_dump_data(&response.data[0], response.inner.length);
  		rv = usb_raw_ep0_write(fd, (struct usb_raw_ep_io*)&response);
  	} else {
  		rv = usb_raw_ep0_read(fd, (struct usb_raw_ep_io*)&response);
  		debug("syz_usb_control_io: read %d bytes\n", response.inner.length);
  		debug_dump_data(&response.data[0], response.inner.length);
  	}
  	if (rv < 0) {
  		debug("syz_usb_control_io: usb_raw_ep0_read/write failed with %d\n", rv);
  		return rv;
  	}
  
  	sleep_ms(200);
  
  	return 0;
  }
  #endif
  
  #if SYZ_EXECUTOR || __NR_syz_usb_ep_write
  static volatile long syz_usb_ep_write(volatile long a0, volatile long a1, volatile long a2, volatile long a3)
  {
  	int fd = a0;
  	uint16 ep = a1;
  	uint32 len = a2;
  	char* data = (char*)a3;
  
  	struct usb_raw_ep_io_data io_data;
  	io_data.inner.ep = ep;
  	io_data.inner.flags = 0;
  	if (len > sizeof(io_data.data))
  		len = sizeof(io_data.data);
  	io_data.inner.length = len;
  	NONFAILING(memcpy(&io_data.data[0], data, len));
  
  	int rv = usb_raw_ep_write(fd, (struct usb_raw_ep_io*)&io_data);
  	if (rv < 0) {
  		debug("syz_usb_ep_write: usb_raw_ep_write failed with %d\n", rv);
  		return rv;
  	}
  
  	sleep_ms(200);
  
  	return 0;
  }
  #endif
  
  #if SYZ_EXECUTOR || __NR_syz_usb_ep_read
  static volatile long syz_usb_ep_read(volatile long a0, volatile long a1, volatile long a2, volatile long a3)
  {
  	int fd = a0;
  	uint16 ep = a1;
  	uint32 len = a2;
  	char* data = (char*)a3;
  
  	struct usb_raw_ep_io_data io_data;
  	io_data.inner.ep = ep;
  	io_data.inner.flags = 0;
  	if (len > sizeof(io_data.data))
  		len = sizeof(io_data.data);
  	io_data.inner.length = len;
  
  	int rv = usb_raw_ep_read(fd, (struct usb_raw_ep_io*)&io_data);
  	if (rv < 0) {
  		debug("syz_usb_ep_read: usb_raw_ep_read failed with %d\n", rv);
  		return rv;
  	}
  
  	NONFAILING(memcpy(&data[0], &io_data.data[0], io_data.inner.length));
  
  	debug("syz_usb_ep_read: received data:\n");
  	debug_dump_data(&io_data.data[0], io_data.inner.length);
  
  	sleep_ms(200);
  
  	return 0;
  }
  #endif
  
  #if SYZ_EXECUTOR || __NR_syz_usb_disconnect
  static volatile long syz_usb_disconnect(volatile long a0)
  {
  	int fd = a0;
  
  	int rv = close(fd);
  
  	sleep_ms(200);
  
  	return rv;
  }
  #endif
  