1/*
2 * Copyright (c) 2020-2022 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 "fido.h"
9#include "fido/config.h"
10#include "fido/es256.h"
11
12#define CMD_ENABLE_ENTATTEST	0x01
13#define CMD_TOGGLE_ALWAYS_UV	0x02
14#define CMD_SET_PIN_MINLEN	0x03
15
16static int
17config_prepare_hmac(uint8_t subcmd, const cbor_item_t *item, fido_blob_t *hmac)
18{
19	uint8_t prefix[32 + 2 * sizeof(uint8_t)], cbor[128];
20	size_t cbor_len = 0;
21
22	memset(prefix, 0xff, sizeof(prefix));
23	prefix[sizeof(prefix) - 2] = CTAP_CBOR_CONFIG;
24	prefix[sizeof(prefix) - 1] = subcmd;
25
26	if (item != NULL) {
27		if ((cbor_len = cbor_serialize(item, cbor, sizeof(cbor))) == 0) {
28			fido_log_debug("%s: cbor_serialize", __func__);
29			return -1;
30		}
31	}
32	if ((hmac->ptr = malloc(cbor_len + sizeof(prefix))) == NULL) {
33		fido_log_debug("%s: malloc", __func__);
34		return -1;
35	}
36	memcpy(hmac->ptr, prefix, sizeof(prefix));
37	memcpy(hmac->ptr + sizeof(prefix), cbor, cbor_len);
38	hmac->len = cbor_len + sizeof(prefix);
39
40	return 0;
41}
42
43static int
44config_tx(fido_dev_t *dev, uint8_t subcmd, cbor_item_t **paramv, size_t paramc,
45    const char *pin, int *ms)
46{
47	cbor_item_t *argv[4];
48	es256_pk_t *pk = NULL;
49	fido_blob_t *ecdh = NULL, f, hmac;
50	const uint8_t cmd = CTAP_CBOR_CONFIG;
51	int r = FIDO_ERR_INTERNAL;
52
53	memset(&f, 0, sizeof(f));
54	memset(&hmac, 0, sizeof(hmac));
55	memset(&argv, 0, sizeof(argv));
56
57	/* subCommand */
58	if ((argv[0] = cbor_build_uint8(subcmd)) == NULL) {
59		fido_log_debug("%s: cbor encode", __func__);
60		goto fail;
61	}
62
63	/* subCommandParams */
64	if (paramc != 0 &&
65	    (argv[1] = cbor_flatten_vector(paramv, paramc)) == NULL) {
66		fido_log_debug("%s: cbor_flatten_vector", __func__);
67		goto fail;
68	}
69
70	/* pinProtocol, pinAuth */
71	if (pin != NULL ||
72	    (fido_dev_supports_permissions(dev) && fido_dev_has_uv(dev))) {
73		if (config_prepare_hmac(subcmd, argv[1], &hmac) < 0) {
74			fido_log_debug("%s: config_prepare_hmac", __func__);
75			goto fail;
76		}
77		if ((r = fido_do_ecdh(dev, &pk, &ecdh, ms)) != FIDO_OK) {
78			fido_log_debug("%s: fido_do_ecdh", __func__);
79			goto fail;
80		}
81		if ((r = cbor_add_uv_params(dev, cmd, &hmac, pk, ecdh, pin,
82		    NULL, &argv[3], &argv[2], ms)) != FIDO_OK) {
83			fido_log_debug("%s: cbor_add_uv_params", __func__);
84			goto fail;
85		}
86	}
87
88	/* framing and transmission */
89	if (cbor_build_frame(cmd, argv, nitems(argv), &f) < 0 ||
90	    fido_tx(dev, CTAP_CMD_CBOR, f.ptr, f.len, ms) < 0) {
91		fido_log_debug("%s: fido_tx", __func__);
92		r = FIDO_ERR_TX;
93		goto fail;
94	}
95
96	r = FIDO_OK;
97fail:
98	cbor_vector_free(argv, nitems(argv));
99	es256_pk_free(&pk);
100	fido_blob_free(&ecdh);
101	free(f.ptr);
102	free(hmac.ptr);
103
104	return r;
105}
106
107static int
108config_enable_entattest_wait(fido_dev_t *dev, const char *pin, int *ms)
109{
110	int r;
111
112	if ((r = config_tx(dev, CMD_ENABLE_ENTATTEST, NULL, 0, pin,
113	    ms)) != FIDO_OK)
114		return r;
115
116	return fido_rx_cbor_status(dev, ms);
117}
118
119int
120fido_dev_enable_entattest(fido_dev_t *dev, const char *pin)
121{
122	int ms = dev->timeout_ms;
123
124	return (config_enable_entattest_wait(dev, pin, &ms));
125}
126
127static int
128config_toggle_always_uv_wait(fido_dev_t *dev, const char *pin, int *ms)
129{
130	int r;
131
132	if ((r = config_tx(dev, CMD_TOGGLE_ALWAYS_UV, NULL, 0, pin,
133	    ms)) != FIDO_OK)
134		return r;
135
136	return (fido_rx_cbor_status(dev, ms));
137}
138
139int
140fido_dev_toggle_always_uv(fido_dev_t *dev, const char *pin)
141{
142	int ms = dev->timeout_ms;
143
144	return config_toggle_always_uv_wait(dev, pin, &ms);
145}
146
147static int
148config_pin_minlen_tx(fido_dev_t *dev, size_t len, bool force,
149    const fido_str_array_t *rpid, const char *pin, int *ms)
150{
151	cbor_item_t *argv[3];
152	int r;
153
154	memset(argv, 0, sizeof(argv));
155
156	if ((rpid == NULL && len == 0 && !force) || len > UINT8_MAX) {
157		r = FIDO_ERR_INVALID_ARGUMENT;
158		goto fail;
159	}
160	if (len && (argv[0] = cbor_build_uint8((uint8_t)len)) == NULL) {
161		fido_log_debug("%s: cbor_encode_uint8", __func__);
162		r = FIDO_ERR_INTERNAL;
163		goto fail;
164	}
165	if (rpid != NULL && (argv[1] = cbor_encode_str_array(rpid)) == NULL) {
166		fido_log_debug("%s: cbor_encode_str_array", __func__);
167		r = FIDO_ERR_INTERNAL;
168		goto fail;
169	}
170	if (force && (argv[2] = cbor_build_bool(true)) == NULL) {
171		fido_log_debug("%s: cbor_build_bool", __func__);
172		r = FIDO_ERR_INTERNAL;
173		goto fail;
174	}
175	if ((r = config_tx(dev, CMD_SET_PIN_MINLEN, argv, nitems(argv),
176	    pin, ms)) != FIDO_OK) {
177		fido_log_debug("%s: config_tx", __func__);
178		goto fail;
179	}
180
181fail:
182	cbor_vector_free(argv, nitems(argv));
183
184	return r;
185}
186
187static int
188config_pin_minlen(fido_dev_t *dev, size_t len, bool force,
189    const fido_str_array_t *rpid, const char *pin, int *ms)
190{
191	int r;
192
193	if ((r = config_pin_minlen_tx(dev, len, force, rpid, pin,
194	    ms)) != FIDO_OK)
195		return r;
196
197	return fido_rx_cbor_status(dev, ms);
198}
199
200int
201fido_dev_set_pin_minlen(fido_dev_t *dev, size_t len, const char *pin)
202{
203	int ms = dev->timeout_ms;
204
205	return config_pin_minlen(dev, len, false, NULL, pin, &ms);
206}
207
208int
209fido_dev_force_pin_change(fido_dev_t *dev, const char *pin)
210{
211	int ms = dev->timeout_ms;
212
213	return config_pin_minlen(dev, 0, true, NULL, pin, &ms);
214}
215
216int
217fido_dev_set_pin_minlen_rpid(fido_dev_t *dev, const char * const *rpid,
218    size_t n, const char *pin)
219{
220	fido_str_array_t sa;
221	int ms = dev->timeout_ms;
222	int r;
223
224	memset(&sa, 0, sizeof(sa));
225	if (fido_str_array_pack(&sa, rpid, n) < 0) {
226		fido_log_debug("%s: fido_str_array_pack", __func__);
227		r = FIDO_ERR_INTERNAL;
228		goto fail;
229	}
230	r = config_pin_minlen(dev, 0, false, &sa, pin, &ms);
231fail:
232	fido_str_array_free(&sa);
233
234	return r;
235}
236