devices/usb/backend/fido_backend/
constants.rs

1// Copyright 2024 The ChromiumOS Authors
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use usb_util::DescriptorType;
6
7// How long it takes for the security key to become inactive and time out all previously pending
8// transactions since last activity.
9pub const TRANSACTION_TIMEOUT_MILLIS: u64 = 120_000;
10
11// How long to wait before timing out and canceling a USB transfer from the guest if the host
12// security key is unresponsive.
13pub const USB_TRANSFER_TIMEOUT_MILLIS: u64 = 5_000;
14
15// 5ms is the default USB interrupt polling rate according to specs.
16pub const USB_POLL_RATE_MILLIS: u64 = 5;
17
18// Some applications expect a very short RTT when handling packets between host key and guest, half
19// a millisecond seems like a decent compromise.
20pub const PACKET_POLL_RATE_NANOS: u64 = 50_000;
21
22// Total max number of transactions we can hold in our key. Any more transactions will push older
23// transactions away from the stack.
24pub const MAX_TRANSACTIONS: usize = 4;
25
26// Max number of incoming packets still to be processed by the guest
27pub const U2FHID_MAX_IN_PENDING: usize = 32;
28
29pub const U2FHID_PACKET_SIZE: usize = 64;
30pub const PACKET_INIT_HEADER_SIZE: usize = 7;
31pub const PACKET_CONT_HEADER_SIZE: usize = 5;
32pub const PACKET_INIT_DATA_SIZE: usize = U2FHID_PACKET_SIZE - PACKET_INIT_HEADER_SIZE;
33pub const PACKET_CONT_DATA_SIZE: usize = U2FHID_PACKET_SIZE - PACKET_CONT_HEADER_SIZE;
34
35pub const CID_SIZE: usize = 4;
36pub const BROADCAST_CID: [u8; CID_SIZE] = [0xFF, 0xFF, 0xFF, 0xFF];
37
38pub const NONCE_SIZE: usize = 8;
39pub const EMPTY_NONCE: [u8; NONCE_SIZE] = [0u8; NONCE_SIZE];
40
41// It's a valid init packet only if the 7th bit of the cmd field is set
42pub const PACKET_INIT_VALID_CMD: u8 = 0b1000_0000;
43pub const U2FHID_ERROR_CMD: u8 = 0xBF;
44
45pub const U2FHID_CONTROL_ENDPOINT: u8 = 0x00;
46pub const U2FHID_IN_ENDPOINT: u8 = 0x81;
47pub const U2FHID_OUT_ENDPOINT: u8 = 0x01;
48
49// Generic HID commands
50pub const HID_GET_IDLE: u8 = 0x02;
51pub const HID_SET_IDLE: u8 = 0x0A;
52pub const HID_GET_REPORT_DESC: u8 = 0x22;
53
54pub const HID_MAX_DESCRIPTOR_SIZE: usize = 4096;
55
56// Descriptor data taken from: https://github.com/gl-sergei/u2f-token/blob/master/src/usb-hid.c
57// With minor modifications for our own PID and VID and other strings
58pub const U2FHID_DEVICE_DESC: &[u8] = &[
59    18,
60    DescriptorType::Device as u8,
61    0x10,
62    0x01,
63    0x00,
64    0x00,
65    0x00,
66    0x40,
67    // Google Vendor ID
68    0xd1,
69    0x18,
70    // Unique Product ID
71    0xd0,
72    0xf1,
73    0x00,
74    0x01,
75    0,
76    0,
77    0,
78    1,
79];
80
81pub const HID_REPORT_DESC_HEADER: &[u8] = &[
82    0x06, 0xd0, 0xf1, // Usage Page (FIDO)
83    0x09, 0x01, // Usage (FIDO)
84];
85
86pub const U2FHID_CONFIG_DESC: &[u8] = &[
87    9,
88    DescriptorType::Configuration as u8,
89    /* Configuration Descriptor. */
90    41,
91    0x00, /* wTotalLength. */
92    0x01, /* bNumInterfaces. */
93    0x01, /* bConfigurationValue. */
94    0,    /* iConfiguration. */
95    0x80, /* bmAttributes. */
96    15,   /* bMaxPower (100mA). */
97    /* Interface Descriptor. */
98    9, /* bLength: Interface Descriptor size */
99    DescriptorType::Interface as u8,
100    0,    /* bInterfaceNumber: Number of Interface */
101    0x00, /* bAlternateSetting: Alternate setting */
102    0x02, /* bNumEndpoints: Two endpoints used */
103    0x03, /* bInterfaceClass: HID */
104    0x00, /* bInterfaceSubClass: no boot */
105    0x00, /* bInterfaceProtocol: 0=none */
106    0x00, /* iInterface */
107    /* HID Descriptor. */
108    9,    /* bLength: HID Descriptor size */
109    0x21, /* bDescriptorType: HID */
110    0x10,
111    0x01, /* bcdHID: HID Class Spec release number */
112    0x00, /* bCountryCode: Hardware target country */
113    0x01, /* bNumDescriptors: Number of HID class descriptors to follow */
114    0x22, /* bDescriptorType */
115    0x22,
116    0, /* wItemLength: Total length of Report descriptor */
117    /* Endpoint IN1 Descriptor */
118    7, /* bLength: Endpoint Descriptor size */
119    DescriptorType::Endpoint as u8,
120    0x81, /* bEndpointAddress: (IN1) */
121    0x03, /* bmAttributes: Interrupt */
122    0x40,
123    0x00, /* wMaxPacketSize: 64 */
124    0x05, /* bInterval (5ms) */
125    /* Endpoint OUT1 Descriptor */
126    7, /* bLength: Endpoint Descriptor size */
127    DescriptorType::Endpoint as u8,
128    0x01, /* bEndpointAddress: (OUT1) */
129    0x03, /* bmAttributes: Interrupt */
130    0x40,
131    0x00, /* wMaxPacketSize: 64 */
132    0x05, /* bInterval (5ms) */
133];
134
135pub const HID_REPORT_DESC: &[u8] = &[
136    0x06, 0xd0, 0xf1, /* USAGE_PAGE (FIDO Alliance) */
137    0x09, 0x01, /* USAGE (Keyboard) */
138    0xa1, 0x01, /* COLLECTION (Application) */
139    0x09, 0x20, /* USAGE (Input report data) */
140    0x15, 0x00, /* LOGICAL_MINIMUM (0) */
141    0x26, 0xff, 0x00, /* LOGICAL_MAXIMUM (255) */
142    0x75, 0x08, /* REPORT_SIZE (8) */
143    0x95, 0x40, /* REPORT_COUNT (64) */
144    0x81, 0x02, /* INPUT (Data,Var,Abs); Modifier byte */
145    0x09, 0x21, /* USAGE (Output report data) */
146    0x15, 0x00, /* LOGICAL_MINIMUM (0) */
147    0x26, 0xff, 0x00, /* LOGICAL_MAXIMUM (255) */
148    0x75, 0x08, /* REPORT_SIZE (8) */
149    0x95, 0x40, /* REPORT_COUNT (64) */
150    0x91, 0x02, /* OUTPUT (Data,Var,Abs); Modifier byte */
151    0xc0, /* END_COLLECTION */
152];
devices/usb/backend/fido_backend/constants.rs

devices/usb/backend/fido_backend/
constants.rs
