blob: d8db530c32533a7a36cef7d09e4e0c06cf596fd8 [file] [log] [blame]
/*
* Hid gadget driver daemon for FIDO2
*
* Copyright (C) 2019 James.Bottomley@HansenPartnership.com
*
* SPDX-License-Identifier: GPL-2.0-only
*/
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "u2f.h"
#include "u2f_hid.h"
static int dev;
/*
* The FIDO protocol has got to be one of the most screwed
* up on the planet: All the HID frame messages are little endian
* and all the U2F messages are big endian
*/
static void u2f_setbe(int val, uint8_t *buf)
{
buf[0] = (val >> 8) & 0xff;
buf[1] = val & 0xff;
}
static int u2f_getbe(uint8_t *buf)
{
return (buf[0] << 8) + buf[1];
}
static void u2fhid_set_len(U2FHID_FRAME *frame, int len)
{
frame->init.bcntl = len & 0xff;
frame->init.bcnth = (len >> 8) & 0xff;
}
static int get_apdu(uint8_t **ptr)
{
int len;
if (**ptr == 0) {
len = u2f_getbe(*ptr + 1);
*ptr += 3;
} else {
len = *(*ptr)++;
}
return len;
}
static void process_error(uint32_t cid, int err)
{
char buf[HID_RPT_SIZE];
U2FHID_FRAME *reply = (U2FHID_FRAME *)buf;
int count;
memset(buf, 0, sizeof(buf));
reply->cid = cid;
reply->init.cmd = U2FHID_ERROR;
reply->init.bcnth = 0;
reply->init.bcntl = sizeof(reply) + 1;
reply->init.data[0] = err;
count = write(dev, buf, sizeof(buf));
printf("wrote error frame %d\n", count);
}
static int get_payload(U2FHID_FRAME *frame, uint8_t buf[HID_MAX_PAYLOAD])
{
int len = MSG_LEN(*frame);
int count = sizeof(frame->init.data);
int seq = 0;
memcpy(buf, frame->init.data, count);
printf("looking for packet of len %d\n", len);
while (count < len) {
int c = read(dev, frame, HID_RPT_SIZE);
if (c != HID_RPT_SIZE) {
fprintf(stderr, "Got short read of sequence packet %d != %d\n", c, HID_RPT_SIZE);
process_error(frame->cid, ERR_INVALID_LEN);
return -ERR_INVALID_LEN;
}
if (seq++ != frame->cont.seq) {
fprintf(stderr, "Invalid sequence %d != %d\n", seq-1, frame->cont.seq);
return -ERR_INVALID_SEQ;
}
memcpy(&buf[count], frame->cont.data, sizeof(frame->cont.data));
count += sizeof(frame->cont.data);
}
return len;
}
static void send_payload(uint8_t ctap[HID_MAX_PAYLOAD], int len, uint32_t cid)
{
uint8_t buf[HID_RPT_SIZE];
U2FHID_FRAME *frame = (U2FHID_FRAME *)buf;
int count;
int seq = 0;
/* response bytes at end */
u2f_setbe(U2F_SW_NO_ERROR, &ctap[len]);
/* account for response bytes */
len += 2;
frame->cid = cid;
frame->init.cmd = U2FHID_MSG;
u2fhid_set_len(frame, len);
count = sizeof(frame->init.data);
memcpy(frame->init.data, ctap, count);
write(dev, buf, sizeof(buf));
while (count < len) {
frame->cid = cid;
frame->cont.seq = seq++;
memcpy(frame->cont.data, &ctap[count], sizeof(frame->cont.data));
count += sizeof(frame->cont.data);
write(dev, buf, sizeof(buf));
}
}
static void process_version(uint32_t cid)
{
uint8_t buf[HID_RPT_SIZE];
U2FHID_FRAME *frame = (U2FHID_FRAME *)buf;
static const char *repl = "U2F_V2";
const int len = strlen(repl);
memset(buf, 0, sizeof(buf));
frame->cid = cid;
frame->init.cmd = U2FHID_MSG;
frame->init.bcnth = 0;
frame->init.bcntl = len + 2; /* error at end */
memcpy(frame->init.data, repl, len);
u2f_setbe(U2F_SW_NO_ERROR, &frame->init.data[len]);
write(dev, buf, sizeof(buf));
}
static void process_register(uint32_t cid, uint8_t ctap[HID_MAX_PAYLOAD])
{
uint8_t buf[HID_MAX_PAYLOAD];
U2F_REGISTER_REQ *req;
U2F_REGISTER_RESP *resp = (U2F_REGISTER_RESP *)buf;
uint8_t *ptr = &ctap[4]; /* point to APDU lengths */
int len;
len = get_apdu(&ptr);
if (len != sizeof(U2F_REGISTER_REQ)) {
fprintf(stderr, "Wrong REGISTER REQ len %d != %ld\n",
len, sizeof(U2F_REGISTER_REQ));
process_error(cid, ERR_INVALID_CMD);
return;
}
len = get_apdu(&ptr);
/*
* standard seems to require this but Mozilla doesn't transmit it
if (len < sizeof(U2F_REGISTER_RESP)) {
fprintf(stderr, "Wrong REGISTER RESP len %d < %ld\n",
len, sizeof(U2F_REGISTER_RESP));
process_error(cid, ERR_INVALID_CMD);
return;
}
*/
req = (U2F_REGISTER_REQ *)ptr;
printf("chal[0] = %d, appId[0] = %d\n", req->chal[0], req->appId[0]);
memset(buf, 0, sizeof(buf));
resp->registerId = 0x05;
resp->keyHandleLen = 240;
const char *const str = "This is a key handle";
strcpy((char *)resp->keyHandleCertSig, str);
send_payload(buf, sizeof(U2F_REGISTER_RESP), cid);
}
static void process_msg(U2FHID_FRAME *frame)
{
uint8_t ctap[HID_MAX_PAYLOAD];
int len;
int ins;
uint32_t cid = frame->cid;
len = get_payload(frame, ctap);
if (len < 0) {
process_error(frame->cid, -len);
return;
}
ins = ctap[1];
printf("Got CLA=0x%x, ins=0x%x\n", ctap[0], ins);
if (ins == U2F_VERSION) {
printf("U2F VERSION\n");
process_version(cid);
} else if (ins == U2F_REGISTER) {
printf("U2F REGISTER\n");
process_register(cid, ctap);
} else {
printf("Unrecognized command 0x%x\n", ins);
}
}
static void process_init(U2FHID_FRAME *frame)
{
char buf[HID_RPT_SIZE];
U2FHID_FRAME *reply = (U2FHID_FRAME *)buf;
U2FHID_INIT_REQ *req = (U2FHID_INIT_REQ *)frame->init.data;
U2FHID_INIT_RESP *resp = (U2FHID_INIT_RESP *)reply->init.data;
int count;
if (MSG_LEN(*frame) != sizeof(U2FHID_INIT_REQ)) {
fprintf(stderr, "INIT message wrong length %d != %ld\n",
MSG_LEN(*frame),
sizeof(U2FHID_INIT_REQ));
process_error(frame->cid, ERR_INVALID_LEN);
return;
}
if (frame->cid != CID_BROADCAST) {
fprintf(stderr, "INIT message to wrong cid %x\n", frame->cid);
process_error(frame->cid, ERR_INVALID_CMD);
return;
}
memset(buf, 0, sizeof(buf));
reply->cid = CID_BROADCAST;
reply->init.cmd = U2FHID_INIT;
reply->init.bcnth = 0;
reply->init.bcntl = sizeof(*resp);
printf("setting reply size to %ld\n", sizeof(*resp));
memcpy(resp->nonce, req->nonce, sizeof(req->nonce));
resp->cid = 1;
resp->versionInterface = U2FHID_IF_VERSION;
count = write(dev, buf, sizeof(buf));
printf("written %d bytes\n", count);
}
static void command_loop(void)
{
int count;
uint8_t buf[HID_RPT_SIZE];
U2FHID_FRAME *frame = (U2FHID_FRAME *)buf;
count = read(dev, buf, sizeof(buf));
printf("received %d bytes\n", count);
if (frame->init.cmd == U2FHID_INIT) {
printf("Got INIT\n");
process_init(frame);
} else if (frame->init.cmd == U2FHID_MSG){
printf("Got MSG\n");
process_msg(frame);
} else {
printf("Got unknown command 0x%x\n", FRAME_CMD(*frame));
process_error(frame->cid, ERR_INVALID_CMD);
}
}
int main(int argc, const char *argv[])
{
if (argc != 2) {
fprintf(stderr, "need hidg device\n");
exit(1);
}
dev = open(argv[1], O_RDWR);
if (dev < 0) {
perror("Failed to open HIDG");
exit(1);
}
for (;;) {
command_loop();
}
}