From f4a3dc91283f5ab016f166ffec32f9c08e0ba174 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Thu, 11 Apr 2019 15:44:07 +0200 Subject: all: add basic USB fuzzing support This commits implements 4 syzcalls: syz_usb_connect, syz_usb_io_control, syz_usb_ep_write and syz_usb_disconnect. Those syzcalls are used to emit USB packets through a custom GadgetFS-like interface (currently exposed at /sys/kernel/debug/usb-fuzzer), which requires special kernel patches. USB fuzzing support is quite basic, as it mostly covers only the USB device enumeration process. Even though the syz_usb_ep_write syzcall does allow to communicate with USB endpoints after the device has been enumerated, no coverage is collected from that code yet. --- executor/common_usb.h | 452 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 452 insertions(+) create mode 100644 executor/common_usb.h (limited to 'executor/common_usb.h') diff --git a/executor/common_usb.h b/executor/common_usb.h new file mode 100644 index 000000000..a491a2297 --- /dev/null +++ b/executor/common_usb.h @@ -0,0 +1,452 @@ +// 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_MAX_EP_NUM 32 + +struct usb_device_index { + struct usb_device_descriptor* dev; + struct usb_config_descriptor* config; + unsigned config_length; + struct usb_interface_descriptor* iface; + struct usb_endpoint_descriptor* eps[USB_MAX_EP_NUM]; + unsigned eps_num; +}; + +static bool parse_usb_descriptor(char* buffer, size_t length, struct usb_device_index* index) +{ + if (length < sizeof(*index->dev) + sizeof(*index->config) + sizeof(*index->iface)) + return false; + + index->dev = (struct usb_device_descriptor*)buffer; + index->config = (struct usb_config_descriptor*)(buffer + sizeof(*index->dev)); + index->config_length = length - sizeof(*index->dev); + index->iface = (struct usb_interface_descriptor*)(buffer + sizeof(*index->dev) + sizeof(*index->config)); + + index->eps_num = 0; + size_t offset = 0; + + while (true) { + if (offset == length) + break; + if (offset + 1 < length) + break; + uint8 length = buffer[offset]; + uint8 type = buffer[offset + 1]; + if (type == USB_DT_ENDPOINT) { + index->eps[index->eps_num] = (struct usb_endpoint_descriptor*)(buffer + offset); + index->eps_num++; + } + if (index->eps_num == USB_MAX_EP_NUM) + break; + offset += length; + } + + return true; +} + +enum usb_fuzzer_event_type { + USB_FUZZER_EVENT_INVALID, + USB_FUZZER_EVENT_CONNECT, + USB_FUZZER_EVENT_DISCONNECT, + USB_FUZZER_EVENT_SUSPEND, + USB_FUZZER_EVENT_RESUME, + USB_FUZZER_EVENT_CONTROL, +}; + +struct usb_fuzzer_event { + uint32 type; + uint32 length; + char data[0]; +}; + +struct usb_fuzzer_init { + uint64 speed; + const char* driver_name; + const char* device_name; +}; + +struct usb_fuzzer_ep_io { + uint16 ep; + uint16 flags; + uint32 length; + char data[0]; +}; + +#define USB_FUZZER_IOCTL_INIT _IOW('U', 0, struct usb_fuzzer_init) +#define USB_FUZZER_IOCTL_RUN _IO('U', 1) +#define USB_FUZZER_IOCTL_EP0_READ _IOWR('U', 2, struct usb_fuzzer_event) +#define USB_FUZZER_IOCTL_EP0_WRITE _IOW('U', 3, struct usb_fuzzer_ep_io) +#define USB_FUZZER_IOCTL_EP_ENABLE _IOW('U', 4, struct usb_endpoint_descriptor) +#define USB_FUZZER_IOCTL_EP_WRITE _IOW('U', 6, struct usb_fuzzer_ep_io) +#define USB_FUZZER_IOCTL_CONFIGURE _IO('U', 8) +#define USB_FUZZER_IOCTL_VBUS_DRAW _IOW('U', 9, uint32) + +int usb_fuzzer_open() +{ + return open("/sys/kernel/debug/usb-fuzzer", O_RDWR); +} + +int usb_fuzzer_init(int fd, uint32 speed, const char* driver, const char* device) +{ + struct usb_fuzzer_init arg; + arg.speed = speed; + arg.driver_name = driver; + arg.device_name = device; + return ioctl(fd, USB_FUZZER_IOCTL_INIT, &arg); +} + +int usb_fuzzer_run(int fd) +{ + return ioctl(fd, USB_FUZZER_IOCTL_RUN, 0); +} + +int usb_fuzzer_ep0_read(int fd, struct usb_fuzzer_event* event) +{ + return ioctl(fd, USB_FUZZER_IOCTL_EP0_READ, event); +} + +int usb_fuzzer_ep0_write(int fd, struct usb_fuzzer_ep_io* io) +{ + return ioctl(fd, USB_FUZZER_IOCTL_EP0_WRITE, io); +} + +int usb_fuzzer_ep_write(int fd, struct usb_fuzzer_ep_io* io) +{ + return ioctl(fd, USB_FUZZER_IOCTL_EP_WRITE, io); +} + +int usb_fuzzer_ep_enable(int fd, struct usb_endpoint_descriptor* desc) +{ + return ioctl(fd, USB_FUZZER_IOCTL_EP_ENABLE, desc); +} + +int usb_fuzzer_configure(int fd) +{ + return ioctl(fd, USB_FUZZER_IOCTL_CONFIGURE, 0); +} + +int usb_fuzzer_vbus_draw(int fd, uint32 power) +{ + return ioctl(fd, USB_FUZZER_IOCTL_VBUS_DRAW, power); +} + +#define USB_MAX_PACKET_SIZE 1024 + +struct usb_fuzzer_control_event { + struct usb_fuzzer_event inner; + struct usb_ctrlrequest ctrl; +}; + +struct usb_fuzzer_ep_io_data { + struct usb_fuzzer_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 volatile long syz_usb_connect(volatile long a0, volatile long a1, volatile long a2, volatile long a3) +{ + int64_t speed = a0; + int64_t dev_len = a1; + char* dev = (char*)a2; + struct vusb_connect_descriptors* conn_descs = (struct vusb_connect_descriptors*)a3; + + debug("syz_usb_connect: dev: %p\n", dev); + if (!dev) + return -1; + + debug("syz_usb_connect: device data:\n"); + debug_dump_data(dev, dev_len); + + struct usb_device_index index; + memset(&index, 0, sizeof(index)); + int rv = parse_usb_descriptor(dev, dev_len, &index); + if (!rv) + return -1; + debug("syz_usb_connect: parsed usb descriptor\n"); + + int fd = usb_fuzzer_open(); + if (fd < 0) + return -1; + debug("syz_usb_connect: usb_fuzzer_open success\n"); + + char device[32]; + sprintf(&device[0], "dummy_udc.%llu", procid); + rv = usb_fuzzer_init(fd, speed, "dummy_udc", &device[0]); + if (rv < 0) + return -1; + debug("syz_usb_connect: usb_fuzzer_init success\n"); + + rv = usb_fuzzer_run(fd); + if (rv < 0) + return -1; + debug("syz_usb_connect: usb_fuzzer_run success\n"); + + bool done = false; + while (!done) { + char* response_data = NULL; + uint32 response_length = 0; + + unsigned ep; + uint8 str_idx; + + struct usb_fuzzer_control_event event; + event.inner.type = 0; + event.inner.length = sizeof(event.ctrl); + rv = usb_fuzzer_ep0_read(fd, (struct usb_fuzzer_event*)&event); + if (rv < 0) + return -1; + if (event.inner.type != USB_FUZZER_EVENT_CONTROL) + continue; + + debug("syz_usb_connect: bRequestType: 0x%x, bRequest: 0x%x, wValue: 0x%x, wIndex: 0x%x, wLength: %d\n", + event.ctrl.bRequestType, event.ctrl.bRequest, event.ctrl.wValue, event.ctrl.wIndex, event.ctrl.wLength); + + switch (event.ctrl.bRequestType & USB_TYPE_MASK) { + case USB_TYPE_STANDARD: + switch (event.ctrl.bRequest) { + case USB_REQ_GET_DESCRIPTOR: + switch (event.ctrl.wValue >> 8) { + case USB_DT_DEVICE: + response_data = (char*)index.dev; + response_length = sizeof(*index.dev); + goto reply; + case USB_DT_CONFIG: + response_data = (char*)index.config; + response_length = index.config_length; + goto reply; + case USB_DT_STRING: + str_idx = (uint8)event.ctrl.wValue; + if (str_idx >= conn_descs->strs_len) + goto reply; + response_data = conn_descs->strs[str_idx].str; + response_length = conn_descs->strs[str_idx].len; + goto reply; + case USB_DT_BOS: + response_data = conn_descs->bos; + response_length = conn_descs->bos_len; + goto reply; + case USB_DT_DEVICE_QUALIFIER: + response_data = conn_descs->qual; + response_length = conn_descs->qual_len; + goto reply; + default: + fail("syz_usb_connect: no response"); + continue; + } + break; + case USB_REQ_SET_CONFIGURATION: + rv = usb_fuzzer_vbus_draw(fd, index.config->bMaxPower); + if (rv < 0) + return -1; + rv = usb_fuzzer_configure(fd); + if (rv < 0) + return -1; + for (ep = 0; ep < index.eps_num; ep++) { + rv = usb_fuzzer_ep_enable(fd, index.eps[ep]); + if (rv < 0) + fail("syz_usb_connect: ep enable failed"); + } + done = true; + goto reply; + default: + fail("syz_usb_connect: no response"); + continue; + } + break; + default: + fail("syz_usb_connect: no response"); + continue; + } + + struct usb_fuzzer_ep_io_data response; + + reply: + response.inner.ep = 0; + response.inner.flags = 0; + if (response_length > sizeof(response.data)) + response_length = 0; + response.inner.length = response_length; + if (response_data) + memcpy(&response.data[0], response_data, response_length); + if (event.ctrl.wLength < response.inner.length) + response.inner.length = event.ctrl.wLength; + debug("syz_usb_connect: reply length = %d\n", response.inner.length); + usb_fuzzer_ep0_write(fd, (struct usb_fuzzer_ep_io*)&response); + } + + 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 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_fuzzer_control_event event; + event.inner.type = 0; + event.inner.length = sizeof(event.ctrl); + int rv = usb_fuzzer_ep0_read(fd, (struct usb_fuzzer_event*)&event); + if (rv < 0) + return -1; + if (event.inner.type != USB_FUZZER_EVENT_CONTROL) + return -1; + + debug("syz_usb_control_io: bRequestType: 0x%x, bRequest: 0x%x, wValue: 0x%x, wIndex: 0x%x, wLength: %d\n", + event.ctrl.bRequestType, event.ctrl.bRequest, event.ctrl.wValue, event.ctrl.wIndex, event.ctrl.wLength); + + uint8 req = event.ctrl.bRequest; + uint8 req_type = event.ctrl.bRequestType & USB_TYPE_MASK; + uint8 desc_type = event.ctrl.wValue >> 8; + + char* response_data = NULL; + uint32 response_length = 0; + + if (req == USB_REQ_GET_DESCRIPTOR) { + int i; + int descs_num = (descs->len - offsetof(struct vusb_descriptors, descs)) / sizeof(descs->descs[0]); + + 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]; + goto reply; + } + } + + if (descs->generic) { + response_data = &descs->generic->data[0]; + response_length = descs->generic->len; + goto reply; + } + } else { + int i; + int resps_num = (resps->len - offsetof(struct vusb_responses, resps)) / sizeof(resps->resps[0]); + + 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]; + goto reply; + } + } + + if (resps->generic) { + response_data = &resps->generic->data[0]; + response_length = resps->generic->len; + goto reply; + } + } + + return -1; + + struct usb_fuzzer_ep_io_data response; + +reply: + response.inner.ep = 0; + response.inner.flags = 0; + if (response_length > sizeof(response.data)) + response_length = 0; + response.inner.length = response_length; + if (response_data) + memcpy(&response.data[0], response_data, response_length); + if (event.ctrl.wLength < response.inner.length) + response.inner.length = event.ctrl.wLength; + debug("syz_usb_control_io: reply length = %d\n", response.inner.length); + usb_fuzzer_ep0_write(fd, (struct usb_fuzzer_ep_io*)&response); + + 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_fuzzer_ep_io_data response; + response.inner.ep = ep; + response.inner.flags = 0; + if (len > sizeof(response.data)) + len = 0; + response.inner.length = len; + if (data) + memcpy(&response.data[0], data, len); + + return usb_fuzzer_ep_write(fd, (struct usb_fuzzer_ep_io*)&response); +} +#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 -- cgit mrf-deployment