/libfido2/src/nfc.c

Source
/*
 * Copyright (c) 2020-2024 Yubico AB. All rights reserved.
 * Use of this source code is governed by a BSD-style
 * license that can be found in the LICENSE file.
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <stdio.h>
#include <string.h>

#include "fido.h"
#include "fido/param.h"
#include "iso7816.h"

#define TX_CHUNK_SIZE   240

static const uint8_t aid[] = { 0xa0, 0x00, 0x00, 0x06, 0x47, 0x2f, 0x00, 0x01 };
static const uint8_t v_u2f[] = { 'U', '2', 'F', '_', 'V', '2' };
static const uint8_t v_fido[] = { 'F', 'I', 'D', 'O', '_', '2', '_', '0' };

static int
tx_short_apdu(fido_dev_t *d, const iso7816_header_t *h, const uint8_t *payload,
    uint8_t payload_len, uint8_t cla_flags)
{
        uint8_t apdu[5 + UINT8_MAX + 1];
        uint8_t sw[2];
        size_t apdu_len;
        int ok = -1;

        memset(&apdu, 0, sizeof(apdu));
        apdu[0] = h->cla | cla_flags;
        apdu[1] = h->ins;
        apdu[2] = h->p1;
        apdu[3] = h->p2;
        apdu[4] = payload_len;
        memcpy(&apdu[5], payload, payload_len);
        apdu_len = (size_t)(5 + payload_len);

        if (!(cla_flags & 0x10))
                apdu_len += 1;

        if (d->io.write(d->io_handle, apdu, apdu_len) < 0) {
                fido_log_debug("%s: write", __func__);
                goto fail;
        }

        if (cla_flags & 0x10) {
                if (d->io.read(d->io_handle, sw, sizeof(sw), -1) != 2) {
                        fido_log_debug("%s: read", __func__);
                        goto fail;
                }
                if ((sw[0] << 8 | sw[1]) != SW_NO_ERROR) {
                        fido_log_debug("%s: unexpected sw", __func__);
                        goto fail;
                }
        }

        ok = 0;
fail:
        explicit_bzero(apdu, sizeof(apdu));

        return ok;
}

static int
nfc_do_tx(fido_dev_t *d, const uint8_t *apdu_ptr, size_t apdu_len)
{
        iso7816_header_t h;

        if (fido_buf_read(&apdu_ptr, &apdu_len, &h, sizeof(h)) < 0) {
                fido_log_debug("%s: header", __func__);
                return -1;
        }
        if (apdu_len < 2) {
                fido_log_debug("%s: apdu_len %zu", __func__, apdu_len);
                return -1;
        }

        apdu_len -= 2; /* trim le1 le2 */

        while (apdu_len > TX_CHUNK_SIZE) {
                if (tx_short_apdu(d, &h, apdu_ptr, TX_CHUNK_SIZE, 0x10) < 0) {
                        fido_log_debug("%s: chain", __func__);
                        return -1;
                }
                apdu_ptr += TX_CHUNK_SIZE;
                apdu_len -= TX_CHUNK_SIZE;
        }

        if (tx_short_apdu(d, &h, apdu_ptr, (uint8_t)apdu_len, 0) < 0) {
                fido_log_debug("%s: tx_short_apdu", __func__);
                return -1;
        }

        return 0;
}

int
fido_nfc_tx(fido_dev_t *d, uint8_t cmd, const unsigned char *buf, size_t count)
{
        iso7816_apdu_t *apdu = NULL;
        const uint8_t *ptr;
        size_t len;
        int ok = -1;

        switch (cmd) {
        case CTAP_CMD_INIT: /* select */
                if ((apdu = iso7816_new(0, 0xa4, 0x04, sizeof(aid))) == NULL ||
                    iso7816_add(apdu, aid, sizeof(aid)) < 0) {
                        fido_log_debug("%s: iso7816", __func__);
                        goto fail;
                }
                break;
        case CTAP_CMD_CBOR: /* wrap cbor */
                if (count > UINT16_MAX || (apdu = iso7816_new(0x80, 0x10, 0x00,
                    (uint16_t)count)) == NULL ||
                    iso7816_add(apdu, buf, count) < 0) {
                        fido_log_debug("%s: iso7816", __func__);
                        goto fail;
                }
                break;
        case CTAP_CMD_MSG: /* already an apdu */
                break;
        default:
                fido_log_debug("%s: cmd=%02x", __func__, cmd);
                goto fail;
        }

        if (apdu != NULL) {
                ptr = iso7816_ptr(apdu);
                len = iso7816_len(apdu);
        } else {
                ptr = buf;
                len = count;
        }

        if (nfc_do_tx(d, ptr, len) < 0) {
                fido_log_debug("%s: nfc_do_tx", __func__);
                goto fail;
        }

        ok = 0;
fail:
        iso7816_free(&apdu);

        return ok;
}

static int
tx_get_response(fido_dev_t *d, uint8_t count, bool cbor)
{
        uint8_t apdu[5];

        memset(apdu, 0, sizeof(apdu));
        apdu[0] = cbor ? 0x80 : 0x00;
        apdu[1] = 0xc0; /* GET_RESPONSE */
        apdu[4] = count;

        if (d->io.write(d->io_handle, apdu, sizeof(apdu)) < 0) {
                fido_log_debug("%s: write", __func__);
                return -1;
        }

        return 0;
}

static int
rx_apdu(fido_dev_t *d, uint8_t sw[2], unsigned char **buf, size_t *count, int *ms)
{
        uint8_t f[256 + 2];
        struct timespec ts;
        int n, ok = -1;

        if (fido_time_now(&ts) != 0)
                goto fail;

        if ((n = d->io.read(d->io_handle, f, sizeof(f), *ms)) < 2) {
                fido_log_debug("%s: read", __func__);
                goto fail;
        }

        if (fido_time_delta(&ts, ms) != 0)
                goto fail;

        if (fido_buf_write(buf, count, f, (size_t)(n - 2)) < 0) {
                fido_log_debug("%s: fido_buf_write", __func__);
                goto fail;
        }

        memcpy(sw, f + n - 2, 2);

        ok = 0;
fail:
        explicit_bzero(f, sizeof(f));

        return ok;
}

static int
rx_msg(fido_dev_t *d, unsigned char *buf, size_t count, int ms, bool cbor)
{
        uint8_t sw[2];
        const size_t bufsiz = count;

        if (rx_apdu(d, sw, &buf, &count, &ms) < 0) {
                fido_log_debug("%s: preamble", __func__);
                return -1;
        }

        while (sw[0] == SW1_MORE_DATA)
                if (tx_get_response(d, sw[1], cbor) < 0 ||
                    rx_apdu(d, sw, &buf, &count, &ms) < 0) {
                        fido_log_debug("%s: chain", __func__);
                        return -1;
                }

        if (fido_buf_write(&buf, &count, sw, sizeof(sw)) < 0) {
                fido_log_debug("%s: sw", __func__);
                return -1;
        }

        if (bufsiz - count > INT_MAX) {
                fido_log_debug("%s: bufsiz", __func__);
                return -1;
        }

        return (int)(bufsiz - count);
}

static int
rx_cbor(fido_dev_t *d, unsigned char *buf, size_t count, int ms)
{
        int r;

        if ((r = rx_msg(d, buf, count, ms, true)) < 2)
                return -1;

        return r - 2;
}

static int
rx_init(fido_dev_t *d, unsigned char *buf, size_t count, int ms)
{
        fido_ctap_info_t *attr = (fido_ctap_info_t *)buf;
        uint8_t f[64];
        int n;

        if (count != sizeof(*attr)) {
                fido_log_debug("%s: count=%zu", __func__, count);
                return -1;
        }

        memset(attr, 0, sizeof(*attr));

        if ((n = rx_msg(d, f, sizeof(f), ms, false)) < 2 ||
            (f[n - 2] << 8 | f[n - 1]) != SW_NO_ERROR) {
                fido_log_debug("%s: read", __func__);
                return -1;
        }

        n -= 2;

        if (n == sizeof(v_u2f) && memcmp(f, v_u2f, sizeof(v_u2f)) == 0)
                attr->flags = FIDO_CAP_CBOR;
        else if (n == sizeof(v_fido) && memcmp(f, v_fido, sizeof(v_fido)) == 0)
                attr->flags = FIDO_CAP_CBOR | FIDO_CAP_NMSG;
        else {
                fido_log_debug("%s: unknown version string", __func__);
#ifdef FIDO_FUZZ
                attr->flags = FIDO_CAP_CBOR | FIDO_CAP_NMSG;
#else
                return -1;
#endif
        }

        memcpy(&attr->nonce, &d->nonce, sizeof(attr->nonce)); /* XXX */

        return (int)count;
}

int
fido_nfc_rx(fido_dev_t *d, uint8_t cmd, unsigned char *buf, size_t count, int ms)
{
        switch (cmd) {
        case CTAP_CMD_INIT:
                return rx_init(d, buf, count, ms);
        case CTAP_CMD_CBOR:
                return rx_cbor(d, buf, count, ms);
        case CTAP_CMD_MSG:
                return rx_msg(d, buf, count, ms, false);
        default:
                fido_log_debug("%s: cmd=%02x", __func__, cmd);
                return -1;
        }
}

bool
nfc_is_fido(const char *path)
{
        bool fido = false;
        fido_dev_t *d;
        int r;

        if ((d = fido_dev_new()) == NULL) {
                fido_log_debug("%s: fido_dev_new", __func__);
                goto fail;
        }
        /* fido_dev_open selects the fido applet */
        if ((r = fido_dev_open(d, path)) != FIDO_OK) {
                fido_log_debug("%s: fido_dev_open: 0x%x", __func__, r);
                goto fail;
        }
        if ((r = fido_dev_close(d)) != FIDO_OK) {
                fido_log_debug("%s: fido_dev_close: 0x%x", __func__, r);
                goto fail;

        }

        fido = true;
fail:
        fido_dev_free(&d);

        return fido;
}

#ifdef USE_NFC
bool
fido_is_nfc(const char *path)
{
        return strncmp(path, FIDO_NFC_PREFIX, strlen(FIDO_NFC_PREFIX)) == 0;
}

int
fido_dev_set_nfc(fido_dev_t *d)
{
        if (d->io_handle != NULL) {
                fido_log_debug("%s: device open", __func__);
                return -1;
        }
        d->io_own = true;
        d->io = (fido_dev_io_t) {
                fido_nfc_open,
                fido_nfc_close,
                fido_nfc_read,
                fido_nfc_write,
        };
        d->transport = (fido_dev_transport_t) {
                fido_nfc_rx,
                fido_nfc_tx,
        };

        return 0;
}
#endif /* USE_NFC */

Coverage Report

Created: 2025-10-04 18:33

Line	Count	Source
1		/*
2		* Copyright (c) 2020-2024 Yubico AB. All rights reserved.
3		* Use of this source code is governed by a BSD-style
4		* license that can be found in the LICENSE file.
5		* SPDX-License-Identifier: BSD-2-Clause
6		*/
7
8		#include <stdio.h>
9		#include <string.h>
10
11		#include "fido.h"
12		#include "fido/param.h"
13		#include "iso7816.h"
14
15	24.8k	#define TX_CHUNK_SIZE 240
16
17		static const uint8_t aid[] = { 0xa0, 0x00, 0x00, 0x06, 0x47, 0x2f, 0x00, 0x01 };
18		static const uint8_t v_u2f[] = { 'U', '2', 'F', '_', 'V', '2' };
19		static const uint8_t v_fido[] = { 'F', 'I', 'D', 'O', '_', '2', '_', '0' };
20
21		static int
22		tx_short_apdu(fido_dev_t d, const iso7816_header_t h, const uint8_t *payload,
23		uint8_t payload_len, uint8_t cla_flags)
24	24.2k	{
25	24.2k	uint8_t apdu[5 + UINT8_MAX + 1];
26	24.2k	uint8_t sw[2];
27	24.2k	size_t apdu_len;
28	24.2k	int ok = -1;
29
30	24.2k	memset(&apdu, 0, sizeof(apdu));
31	24.2k	apdu[0] = h->cla \| cla_flags;
32	24.2k	apdu[1] = h->ins;
33	24.2k	apdu[2] = h->p1;
34	24.2k	apdu[3] = h->p2;
35	24.2k	apdu[4] = payload_len;
36	24.2k	memcpy(&apdu[5], payload, payload_len);
37	24.2k	apdu_len = (size_t)(5 + payload_len);
38
39	24.2k	if (!(cla_flags & 0x10))
40	23.7k	apdu_len += 1;
41
42	24.2k	if (d->io.write(d->io_handle, apdu, apdu_len) < 0) {
43	725	fido_log_debug("%s: write", __func__);
44	725	goto fail;
45	725	}
46
47	23.5k	if (cla_flags & 0x10) {
48	515	if (d->io.read(d->io_handle, sw, sizeof(sw), -1) != 2) {
49	427	fido_log_debug("%s: read", __func__);
50	427	goto fail;
51	427	}
52	88	if ((sw[0] << 8 \| sw[1]) != SW_NO_ERROR) {
53	66	fido_log_debug("%s: unexpected sw", __func__);
54	66	goto fail;
55	66	}
56	88	}
57
58	23.0k	ok = 0;
59	24.2k	fail:
60	24.2k	explicit_bzero(apdu, sizeof(apdu));
61
62	24.2k	return ok;
63	23.0k	}
64
65		static int
66		nfc_do_tx(fido_dev_t d, const uint8_t apdu_ptr, size_t apdu_len)
67	24.4k	{
68	24.4k	iso7816_header_t h;
69
70	24.4k	if (fido_buf_read(&apdu_ptr, &apdu_len, &h, sizeof(h)) < 0) {
71	193	fido_log_debug("%s: header", __func__);
72	193	return -1;
73	193	}
74	24.2k	if (apdu_len < 2) {
75	15	fido_log_debug("%s: apdu_len %zu", __func__, apdu_len);
76	15	return -1;
77	15	}
78
79	24.2k	apdu_len -= 2; /* trim le1 le2 */
80
81	24.2k	while (apdu_len > TX_CHUNK_SIZE) {
82	525	if (tx_short_apdu(d, &h, apdu_ptr, TX_CHUNK_SIZE, 0x10) < 0) {
83	503	fido_log_debug("%s: chain", __func__);
84	503	return -1;
85	503	}
86	22	apdu_ptr += TX_CHUNK_SIZE;
87	22	apdu_len -= TX_CHUNK_SIZE;
88	22	}
89
90	23.7k	if (tx_short_apdu(d, &h, apdu_ptr, (uint8_t)apdu_len, 0) < 0) {
91	715	fido_log_debug("%s: tx_short_apdu", __func__);
92	715	return -1;
93	715	}
94
95	23.0k	return 0;
96	23.7k	}
97
98		int
99		fido_nfc_tx(fido_dev_t d, uint8_t cmd, const unsigned char buf, size_t count)
100	25.9k	{
101	25.9k	iso7816_apdu_t *apdu = NULL;
102	25.9k	const uint8_t *ptr;
103	25.9k	size_t len;
104	25.9k	int ok = -1;
105
106	25.9k	switch (cmd) {
107	19.4k	case CTAP_CMD_INIT: /* select */
108	19.4k	if ((apdu = iso7816_new(0, 0xa4, 0x04, sizeof(aid))) == NULL \|\|
109	19.4k	iso7816_add(apdu, aid, sizeof(aid)) < 0) {
110	456	fido_log_debug("%s: iso7816", __func__);
111	456	goto fail;
112	456	}
113	18.9k	break;
114	18.9k	case CTAP_CMD_CBOR: /* wrap cbor */
115	3.63k	if (count > UINT16_MAX \|\| (apdu = iso7816_new(0x80, 0x10, 0x00,
116	3.63k	(uint16_t)count)) == NULL \|\|
117	3.63k	iso7816_add(apdu, buf, count) < 0) {
118	235	fido_log_debug("%s: iso7816", __func__);
119	235	goto fail;
120	235	}
121	3.39k	break;
122	3.39k	case CTAP_CMD_MSG: /* already an apdu */
123	2.08k	break;
124	873	default:
125	873	fido_log_debug("%s: cmd=%02x", __func__, cmd);
126	873	goto fail;
127	25.9k	}
128
129	24.4k	if (apdu != NULL) {
130	22.3k	ptr = iso7816_ptr(apdu);
131	22.3k	len = iso7816_len(apdu);
132	22.3k	} else {
133	2.08k	ptr = buf;
134	2.08k	len = count;
135	2.08k	}
136
137	24.4k	if (nfc_do_tx(d, ptr, len) < 0) {
138	1.42k	fido_log_debug("%s: nfc_do_tx", __func__);
139	1.42k	goto fail;
140	1.42k	}
141
142	23.0k	ok = 0;
143	25.9k	fail:
144	25.9k	iso7816_free(&apdu);
145
146	25.9k	return ok;
147	23.0k	}
148
149		static int
150		tx_get_response(fido_dev_t *d, uint8_t count, bool cbor)
151	605	{
152	605	uint8_t apdu[5];
153
154	605	memset(apdu, 0, sizeof(apdu));
155	605	apdu[0] = cbor ? 0x80 : 0x00;
156	605	apdu[1] = 0xc0; /* GET_RESPONSE */
157	605	apdu[4] = count;
158
159	605	if (d->io.write(d->io_handle, apdu, sizeof(apdu)) < 0) {
160	43	fido_log_debug("%s: write", __func__);
161	43	return -1;
162	43	}
163
164	562	return 0;
165	605	}
166
167		static int
168		rx_apdu(fido_dev_t d, uint8_t sw[2], unsigned char buf, size_t count, int *ms)
169	23.4k	{
170	23.4k	uint8_t f[256 + 2];
171	23.4k	struct timespec ts;
172	23.4k	int n, ok = -1;
173
174	23.4k	if (fido_time_now(&ts) != 0)
175	512	goto fail;
176
177	22.9k	if ((n = d->io.read(d->io_handle, f, sizeof(f), *ms)) < 2) {
178	14.0k	fido_log_debug("%s: read", __func__);
179	14.0k	goto fail;
180	14.0k	}
181
182	8.87k	if (fido_time_delta(&ts, ms) != 0)
183	215	goto fail;
184
185	8.65k	if (fido_buf_write(buf, count, f, (size_t)(n - 2)) < 0) {
186	2.05k	fido_log_debug("%s: fido_buf_write", __func__);
187	2.05k	goto fail;
188	2.05k	}
189
190	6.60k	memcpy(sw, f + n - 2, 2);
191
192	6.60k	ok = 0;
193	23.4k	fail:
194	23.4k	explicit_bzero(f, sizeof(f));
195
196	23.4k	return ok;
197	6.60k	}
198
199		static int
200		rx_msg(fido_dev_t d, unsigned char buf, size_t count, int ms, bool cbor)
201	22.8k	{
202	22.8k	uint8_t sw[2];
203	22.8k	const size_t bufsiz = count;
204
205	22.8k	if (rx_apdu(d, sw, &buf, &count, &ms) < 0) {
206	16.2k	fido_log_debug("%s: preamble", __func__);
207	16.2k	return -1;
208	16.2k	}
209
210	6.60k	while (sw[0] == SW1_MORE_DATA)
211	605	if (tx_get_response(d, sw[1], cbor) < 0 \|\|
212	605	rx_apdu(d, sw, &buf, &count, &ms) < 0) {
213	605	fido_log_debug("%s: chain", __func__);
214	605	return -1;
215	605	}
216
217	6.00k	if (fido_buf_write(&buf, &count, sw, sizeof(sw)) < 0) {
218	49	fido_log_debug("%s: sw", __func__);
219	49	return -1;
220	49	}
221
222	5.95k	if (bufsiz - count > INT_MAX) {
223	0	fido_log_debug("%s: bufsiz", __func__);
224	0	return -1;
225	0	}
226
227	5.95k	return (int)(bufsiz - count);
228	5.95k	}
229
230		static int
231		rx_cbor(fido_dev_t d, unsigned char buf, size_t count, int ms)
232	3.27k	{
233	3.27k	int r;
234
235	3.27k	if ((r = rx_msg(d, buf, count, ms, true)) < 2)
236	3.00k	return -1;
237
238	270	return r - 2;
239	3.27k	}
240
241		static int
242		rx_init(fido_dev_t d, unsigned char buf, size_t count, int ms)
243	18.1k	{
244	18.1k	fido_ctap_info_t attr = (fido_ctap_info_t )buf;
245	18.1k	uint8_t f[64];
246	18.1k	int n;
247
248	18.1k	if (count != sizeof(*attr)) {
249	620	fido_log_debug("%s: count=%zu", __func__, count);
250	620	return -1;
251	620	}
252
253	17.5k	memset(attr, 0, sizeof(*attr));
254
255	17.5k	if ((n = rx_msg(d, f, sizeof(f), ms, false)) < 2 \|\|
256	17.5k	(f[n - 2] << 8 \| f[n - 1]) != SW_NO_ERROR) {
257	14.6k	fido_log_debug("%s: read", __func__);
258	14.6k	return -1;
259	14.6k	}
260
261	2.94k	n -= 2;
262
263	2.94k	if (n == sizeof(v_u2f) && memcmp(f, v_u2f, sizeof(v_u2f)) == 0)
264	92	attr->flags = FIDO_CAP_CBOR;
265	2.85k	else if (n == sizeof(v_fido) && memcmp(f, v_fido, sizeof(v_fido)) == 0)
266	83	attr->flags = FIDO_CAP_CBOR \| FIDO_CAP_NMSG;
267	2.76k	else {
268	2.76k	fido_log_debug("%s: unknown version string", __func__);
269	2.76k	#ifdef FIDO_FUZZ
270	2.76k	attr->flags = FIDO_CAP_CBOR \| FIDO_CAP_NMSG;
271		#else
272		return -1;
273		#endif
274	2.76k	}
275
276	2.94k	memcpy(&attr->nonce, &d->nonce, sizeof(attr->nonce)); /* XXX */
277
278	2.94k	return (int)count;
279	17.5k	}
280
281		int
282		fido_nfc_rx(fido_dev_t d, uint8_t cmd, unsigned char buf, size_t count, int ms)
283	24.3k	{
284	24.3k	switch (cmd) {
285	18.1k	case CTAP_CMD_INIT:
286	18.1k	return rx_init(d, buf, count, ms);
287	3.27k	case CTAP_CMD_CBOR:
288	3.27k	return rx_cbor(d, buf, count, ms);
289	2.02k	case CTAP_CMD_MSG:
290	2.02k	return rx_msg(d, buf, count, ms, false);
291	873	default:
292	873	fido_log_debug("%s: cmd=%02x", __func__, cmd);
293	873	return -1;
294	24.3k	}
295	24.3k	}
296
297		bool
298		nfc_is_fido(const char *path)
299	2.80M	{
300	2.80M	bool fido = false;
301	2.80M	fido_dev_t *d;
302	2.80M	int r;
303
304	2.80M	if ((d = fido_dev_new()) == NULL) {
305	7.00k	fido_log_debug("%s: fido_dev_new", __func__);
306	7.00k	goto fail;
307	7.00k	}
308		/* fido_dev_open selects the fido applet */
309	2.79M	if ((r = fido_dev_open(d, path)) != FIDO_OK) {
310	2.79M	fido_log_debug("%s: fido_dev_open: 0x%x", __func__, r);
311	2.79M	goto fail;
312	2.79M	}
313	759	if ((r = fido_dev_close(d)) != FIDO_OK) {
314	0	fido_log_debug("%s: fido_dev_close: 0x%x", __func__, r);
315	0	goto fail;
316
317	0	}
318
319	759	fido = true;
320	2.80M	fail:
321	2.80M	fido_dev_free(&d);
322
323	2.80M	return fido;
324	759	}
325
326		#ifdef USE_NFC
327		bool
328		fido_is_nfc(const char *path)
329	3.15M	{
330	3.15M	return strncmp(path, FIDO_NFC_PREFIX, strlen(FIDO_NFC_PREFIX)) == 0;
331	3.15M	}
332
333		int
334		fido_dev_set_nfc(fido_dev_t *d)
335	2.78M	{
336	2.78M	if (d->io_handle != NULL) {
337	0	fido_log_debug("%s: device open", __func__);
338	0	return -1;
339	0	}
340	2.78M	d->io_own = true;
341	2.78M	d->io = (fido_dev_io_t) {
342	2.78M	fido_nfc_open,
343	2.78M	fido_nfc_close,
344	2.78M	fido_nfc_read,
345	2.78M	fido_nfc_write,
346	2.78M	};
347	2.78M	d->transport = (fido_dev_transport_t) {
348	2.78M	fido_nfc_rx,
349	2.78M	fido_nfc_tx,
350	2.78M	};
351
352	2.78M	return 0;
353	2.78M	}
354		#endif /* USE_NFC */