Coverage Report

Created: 2020-12-02 17:02

/libfido2/src/es256.c
Line
Count
Source (jump to first uncovered line)
1
/*
2
 * Copyright (c) 2018 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
 */
6
7
#include <openssl/bn.h>
8
#include <openssl/ec.h>
9
#include <openssl/evp.h>
10
#include <openssl/obj_mac.h>
11
12
#include <string.h>
13
#include "fido.h"
14
#include "fido/es256.h"
15
16
static int
17
decode_coord(const cbor_item_t *item, void *xy, size_t xy_len)
18
8.60k
{
19
8.60k
        if (cbor_isa_bytestring(item) == false ||
20
8.60k
            cbor_bytestring_is_definite(item) == false ||
21
8.60k
            cbor_bytestring_length(item) != xy_len) {
22
111
                fido_log_debug("%s: cbor type", __func__);
23
111
                return (-1);
24
111
        }
25
8.49k
26
8.49k
        memcpy(xy, cbor_bytestring_handle(item), xy_len);
27
8.49k
28
8.49k
        return (0);
29
8.49k
}
30
31
static int
32
decode_pubkey_point(const cbor_item_t *key, const cbor_item_t *val, void *arg)
33
22.3k
{
34
22.3k
        es256_pk_t *k = arg;
35
22.3k
36
22.3k
        if (cbor_isa_negint(key) == false ||
37
22.3k
            cbor_int_get_width(key) != CBOR_INT_8)
38
11.1k
                return (0); /* ignore */
39
11.2k
40
11.2k
        switch (cbor_get_uint8(key)) {
41
4.39k
        case 1: /* x coordinate */
42
4.39k
                return (decode_coord(val, &k->x, sizeof(k->x)));
43
4.21k
        case 2: /* y coordinate */
44
4.21k
                return (decode_coord(val, &k->y, sizeof(k->y)));
45
2.63k
        }
46
2.63k
47
2.63k
        return (0); /* ignore */
48
2.63k
}
49
50
int
51
es256_pk_decode(const cbor_item_t *item, es256_pk_t *k)
52
4.56k
{
53
4.56k
        if (cbor_isa_map(item) == false ||
54
4.56k
            cbor_map_is_definite(item) == false ||
55
4.56k
            cbor_map_iter(item, k, decode_pubkey_point) < 0) {
56
218
                fido_log_debug("%s: cbor type", __func__);
57
218
                return (-1);
58
218
        }
59
4.34k
60
4.34k
        return (0);
61
4.34k
}
62
63
cbor_item_t *
64
es256_pk_encode(const es256_pk_t *pk, int ecdh)
65
2.88k
{
66
2.88k
        cbor_item_t             *item = NULL;
67
2.88k
        struct cbor_pair         argv[5];
68
2.88k
        int                      alg;
69
2.88k
        int                      ok = -1;
70
2.88k
71
2.88k
        memset(argv, 0, sizeof(argv));
72
2.88k
73
2.88k
        if ((item = cbor_new_definite_map(5)) == NULL)
74
2.88k
                goto fail;
75
2.87k
76
2.87k
        /* kty */
77
2.87k
        if ((argv[0].key = cbor_build_uint8(1)) == NULL ||
78
2.87k
            (argv[0].value = cbor_build_uint8(2)) == NULL ||
79
2.87k
            !cbor_map_add(item, argv[0]))
80
30
                goto fail;
81
2.84k
82
2.84k
        /*
83
2.84k
         * "The COSEAlgorithmIdentifier used is -25 (ECDH-ES +
84
2.84k
         * HKDF-256) although this is NOT the algorithm actually
85
2.84k
         * used. Setting this to a different value may result in
86
2.84k
         * compatibility issues."
87
2.84k
         */
88
2.84k
        if (ecdh)
89
2.80k
                alg = COSE_ECDH_ES256;
90
2.84k
        else
91
2.84k
                alg = COSE_ES256;
92
2.84k
93
2.84k
        /* alg */
94
2.84k
        if ((argv[1].key = cbor_build_uint8(3)) == NULL ||
95
2.84k
            (argv[1].value = cbor_build_negint8((uint8_t)(-alg - 1))) == NULL ||
96
2.84k
            !cbor_map_add(item, argv[1]))
97
27
                goto fail;
98
2.81k
99
2.81k
        /* crv */
100
2.81k
        if ((argv[2].key = cbor_build_negint8(0)) == NULL ||
101
2.81k
            (argv[2].value = cbor_build_uint8(1)) == NULL ||
102
2.81k
            !cbor_map_add(item, argv[2]))
103
31
                goto fail;
104
2.78k
105
2.78k
        /* x */
106
2.78k
        if ((argv[3].key = cbor_build_negint8(1)) == NULL ||
107
2.78k
            (argv[3].value = cbor_build_bytestring(pk->x,
108
2.78k
            sizeof(pk->x))) == NULL || !cbor_map_add(item, argv[3]))
109
28
                goto fail;
110
2.76k
111
2.76k
        /* y */
112
2.76k
        if ((argv[4].key = cbor_build_negint8(2)) == NULL ||
113
2.76k
            (argv[4].value = cbor_build_bytestring(pk->y,
114
2.75k
            sizeof(pk->y))) == NULL || !cbor_map_add(item, argv[4]))
115
26
                goto fail;
116
2.73k
117
2.73k
        ok = 0;
118
2.88k
fail:
119
2.88k
        if (ok < 0) {
120
151
                if (item != NULL) {
121
142
                        cbor_decref(&item);
122
142
                        item = NULL;
123
142
                }
124
151
        }
125
2.88k
126
17.3k
        for (size_t i = 0; i < 5; i++) {
127
14.4k
                if (argv[i].key)
128
14.0k
                        cbor_decref(&argv[i].key);
129
14.4k
                if (argv[i].value)
130
13.9k
                        cbor_decref(&argv[i].value);
131
14.4k
        }
132
2.88k
133
2.88k
        return (item);
134
2.73k
}
135
136
es256_sk_t *
137
es256_sk_new(void)
138
5.01k
{
139
5.01k
        return (calloc(1, sizeof(es256_sk_t)));
140
5.01k
}
141
142
void
143
es256_sk_free(es256_sk_t **skp)
144
5.01k
{
145
5.01k
        es256_sk_t *sk;
146
5.01k
147
5.01k
        if (skp == NULL || (sk = *skp) == NULL)
148
5.01k
                return;
149
4.99k
150
4.99k
        explicit_bzero(sk, sizeof(*sk));
151
4.99k
        free(sk);
152
4.99k
153
4.99k
        *skp = NULL;
154
4.99k
}
155
156
es256_pk_t *
157
es256_pk_new(void)
158
10.1k
{
159
10.1k
        return (calloc(1, sizeof(es256_pk_t)));
160
10.1k
}
161
162
void
163
es256_pk_free(es256_pk_t **pkp)
164
16.2k
{
165
16.2k
        es256_pk_t *pk;
166
16.2k
167
16.2k
        if (pkp == NULL || (pk = *pkp) == NULL)
168
16.2k
                return;
169
10.1k
170
10.1k
        explicit_bzero(pk, sizeof(*pk));
171
10.1k
        free(pk);
172
10.1k
173
10.1k
        *pkp = NULL;
174
10.1k
}
175
176
int
177
es256_pk_from_ptr(es256_pk_t *pk, const void *ptr, size_t len)
178
523
{
179
523
        const uint8_t *p = ptr;
180
523
181
523
        if (len < sizeof(*pk))
182
478
                return (FIDO_ERR_INVALID_ARGUMENT);
183
45
184
45
        if (len == sizeof(*pk) + 1 && *p == 0x04)
185
1
                memcpy(pk, ++p, sizeof(*pk)); /* uncompressed format */
186
44
        else
187
44
                memcpy(pk, ptr, sizeof(*pk)); /* libfido2 x||y format */
188
45
189
45
        return (FIDO_OK);
190
45
}
191
192
int
193
es256_pk_set_x(es256_pk_t *pk, const unsigned char *x)
194
42
{
195
42
        memcpy(pk->x, x, sizeof(pk->x));
196
42
197
42
        return (0);
198
42
}
199
200
int
201
es256_pk_set_y(es256_pk_t *pk, const unsigned char *y)
202
42
{
203
42
        memcpy(pk->y, y, sizeof(pk->y));
204
42
205
42
        return (0);
206
42
}
207
208
int
209
es256_sk_create(es256_sk_t *key)
210
4.97k
{
211
4.97k
        EVP_PKEY_CTX    *pctx = NULL;
212
4.97k
        EVP_PKEY_CTX    *kctx = NULL;
213
4.97k
        EVP_PKEY        *p = NULL;
214
4.97k
        EVP_PKEY        *k = NULL;
215
4.97k
        const EC_KEY    *ec;
216
4.97k
        const BIGNUM    *d;
217
4.97k
        const int        nid = NID_X9_62_prime256v1;
218
4.97k
        int              n;
219
4.97k
        int              ok = -1;
220
4.97k
221
4.97k
        if ((pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_EC, NULL)) == NULL ||
222
4.97k
            EVP_PKEY_paramgen_init(pctx) <= 0 ||
223
4.97k
            EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, nid) <= 0 ||
224
4.97k
            EVP_PKEY_paramgen(pctx, &p) <= 0) {
225
60
                fido_log_debug("%s: EVP_PKEY_paramgen", __func__);
226
60
                goto fail;
227
60
        }
228
4.91k
229
4.91k
        if ((kctx = EVP_PKEY_CTX_new(p, NULL)) == NULL ||
230
4.91k
            EVP_PKEY_keygen_init(kctx) <= 0 || EVP_PKEY_keygen(kctx, &k) <= 0) {
231
50
                fido_log_debug("%s: EVP_PKEY_keygen", __func__);
232
50
                goto fail;
233
50
        }
234
4.86k
235
4.86k
        if ((ec = EVP_PKEY_get0_EC_KEY(k)) == NULL ||
236
4.86k
            (d = EC_KEY_get0_private_key(ec)) == NULL ||
237
4.86k
            (n = BN_num_bytes(d)) < 0 || (size_t)n > sizeof(key->d) ||
238
4.86k
            (n = BN_bn2bin(d, key->d)) < 0 || (size_t)n > sizeof(key->d)) {
239
49
                fido_log_debug("%s: EC_KEY_get0_private_key", __func__);
240
49
                goto fail;
241
49
        }
242
4.81k
243
4.81k
        ok = 0;
244
4.97k
fail:
245
4.97k
        if (p != NULL)
246
4.97k
                EVP_PKEY_free(p);
247
4.97k
        if (k != NULL)
248
4.97k
                EVP_PKEY_free(k);
249
4.97k
        if (pctx != NULL)
250
4.97k
                EVP_PKEY_CTX_free(pctx);
251
4.97k
        if (kctx != NULL)
252
4.97k
                EVP_PKEY_CTX_free(kctx);
253
4.97k
254
4.97k
        return (ok);
255
4.81k
}
256
257
EVP_PKEY *
258
es256_pk_to_EVP_PKEY(const es256_pk_t *k)
259
3.38k
{
260
3.38k
        BN_CTX          *bnctx = NULL;
261
3.38k
        EC_KEY          *ec = NULL;
262
3.38k
        EC_POINT        *q = NULL;
263
3.38k
        EVP_PKEY        *pkey = NULL;
264
3.38k
        BIGNUM          *x = NULL;
265
3.38k
        BIGNUM          *y = NULL;
266
3.38k
        const EC_GROUP  *g = NULL;
267
3.38k
        const int        nid = NID_X9_62_prime256v1;
268
3.38k
        int              ok = -1;
269
3.38k
270
3.38k
        if ((bnctx = BN_CTX_new()) == NULL)
271
3.38k
                goto fail;
272
3.37k
273
3.37k
        BN_CTX_start(bnctx);
274
3.37k
275
3.37k
        if ((x = BN_CTX_get(bnctx)) == NULL ||
276
3.37k
            (y = BN_CTX_get(bnctx)) == NULL)
277
3.37k
                goto fail;
278
3.34k
279
3.34k
        if (BN_bin2bn(k->x, sizeof(k->x), x) == NULL ||
280
3.34k
            BN_bin2bn(k->y, sizeof(k->y), y) == NULL) {
281
28
                fido_log_debug("%s: BN_bin2bn", __func__);
282
28
                goto fail;
283
28
        }
284
3.31k
285
3.31k
        if ((ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
286
3.31k
            (g = EC_KEY_get0_group(ec)) == NULL) {
287
26
                fido_log_debug("%s: EC_KEY init", __func__);
288
26
                goto fail;
289
26
        }
290
3.29k
291
3.29k
        if ((q = EC_POINT_new(g)) == NULL ||
292
3.29k
            EC_POINT_set_affine_coordinates_GFp(g, q, x, y, bnctx) == 0 ||
293
3.29k
            EC_KEY_set_public_key(ec, q) == 0) {
294
201
                fido_log_debug("%s: EC_KEY_set_public_key", __func__);
295
201
                goto fail;
296
201
        }
297
3.08k
298
3.08k
        if ((pkey = EVP_PKEY_new()) == NULL ||
299
3.08k
            EVP_PKEY_assign_EC_KEY(pkey, ec) == 0) {
300
18
                fido_log_debug("%s: EVP_PKEY_assign_EC_KEY", __func__);
301
18
                goto fail;
302
18
        }
303
3.07k
304
3.07k
        ec = NULL; /* at this point, ec belongs to evp */
305
3.07k
306
3.07k
        ok = 0;
307
3.38k
fail:
308
3.38k
        if (bnctx != NULL) {
309
3.37k
                BN_CTX_end(bnctx);
310
3.37k
                BN_CTX_free(bnctx);
311
3.37k
        }
312
3.38k
313
3.38k
        if (ec != NULL)
314
3.38k
                EC_KEY_free(ec);
315
3.38k
        if (q != NULL)
316
3.38k
                EC_POINT_free(q);
317
3.38k
318
3.38k
        if (ok < 0 && pkey != NULL) {
319
8
                EVP_PKEY_free(pkey);
320
8
                pkey = NULL;
321
8
        }
322
3.38k
323
3.38k
        return (pkey);
324
3.07k
}
325
326
int
327
es256_pk_from_EC_KEY(es256_pk_t *pk, const EC_KEY *ec)
328
4.75k
{
329
4.75k
        BN_CTX          *bnctx = NULL;
330
4.75k
        BIGNUM          *x = NULL;
331
4.75k
        BIGNUM          *y = NULL;
332
4.75k
        const EC_POINT  *q = NULL;
333
4.75k
        const EC_GROUP  *g = NULL;
334
4.75k
        int              ok = FIDO_ERR_INTERNAL;
335
4.75k
        int              n;
336
4.75k
337
4.75k
        if ((q = EC_KEY_get0_public_key(ec)) == NULL ||
338
4.75k
            (g = EC_KEY_get0_group(ec)) == NULL ||
339
4.75k
            (bnctx = BN_CTX_new()) == NULL)
340
4.75k
                goto fail;
341
4.72k
342
4.72k
        BN_CTX_start(bnctx);
343
4.72k
344
4.72k
        if ((x = BN_CTX_get(bnctx)) == NULL ||
345
4.72k
            (y = BN_CTX_get(bnctx)) == NULL)
346
4.72k
                goto fail;
347
4.69k
348
4.69k
        if (EC_POINT_get_affine_coordinates_GFp(g, q, x, y, bnctx) == 0 ||
349
4.69k
            (n = BN_num_bytes(x)) < 0 || (size_t)n > sizeof(pk->x) ||
350
4.69k
            (n = BN_num_bytes(y)) < 0 || (size_t)n > sizeof(pk->y)) {
351
16
                fido_log_debug("%s: EC_POINT_get_affine_coordinates_GFp",
352
16
                    __func__);
353
16
                goto fail;
354
16
        }
355
4.67k
356
4.67k
        if ((n = BN_bn2bin(x, pk->x)) < 0 || (size_t)n > sizeof(pk->x) ||
357
4.67k
            (n = BN_bn2bin(y, pk->y)) < 0 || (size_t)n > sizeof(pk->y)) {
358
38
                fido_log_debug("%s: BN_bn2bin", __func__);
359
38
                goto fail;
360
38
        }
361
4.63k
362
4.63k
        ok = FIDO_OK;
363
4.75k
fail:
364
4.75k
        if (bnctx != NULL) {
365
4.72k
                BN_CTX_end(bnctx);
366
4.72k
                BN_CTX_free(bnctx);
367
4.72k
        }
368
4.75k
369
4.75k
        return (ok);
370
4.63k
}
371
372
EVP_PKEY *
373
es256_sk_to_EVP_PKEY(const es256_sk_t *k)
374
3.02k
{
375
3.02k
        BN_CTX          *bnctx = NULL;
376
3.02k
        EC_KEY          *ec = NULL;
377
3.02k
        EVP_PKEY        *pkey = NULL;
378
3.02k
        BIGNUM          *d = NULL;
379
3.02k
        const int        nid = NID_X9_62_prime256v1;
380
3.02k
        int              ok = -1;
381
3.02k
382
3.02k
        if ((bnctx = BN_CTX_new()) == NULL)
383
3.02k
                goto fail;
384
3.01k
385
3.01k
        BN_CTX_start(bnctx);
386
3.01k
387
3.01k
        if ((d = BN_CTX_get(bnctx)) == NULL ||
388
3.01k
            BN_bin2bn(k->d, sizeof(k->d), d) == NULL) {
389
18
                fido_log_debug("%s: BN_bin2bn", __func__);
390
18
                goto fail;
391
18
        }
392
2.99k
393
2.99k
        if ((ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
394
2.99k
            EC_KEY_set_private_key(ec, d) == 0) {
395
6
                fido_log_debug("%s: EC_KEY_set_private_key", __func__);
396
6
                goto fail;
397
6
        }
398
2.99k
399
2.99k
        if ((pkey = EVP_PKEY_new()) == NULL ||
400
2.99k
            EVP_PKEY_assign_EC_KEY(pkey, ec) == 0) {
401
21
                fido_log_debug("%s: EVP_PKEY_assign_EC_KEY", __func__);
402
21
                goto fail;
403
21
        }
404
2.96k
405
2.96k
        ec = NULL; /* at this point, ec belongs to evp */
406
2.96k
407
2.96k
        ok = 0;
408
3.02k
fail:
409
3.02k
        if (bnctx != NULL) {
410
3.01k
                BN_CTX_end(bnctx);
411
3.01k
                BN_CTX_free(bnctx);
412
3.01k
        }
413
3.02k
414
3.02k
        if (ec != NULL)
415
3.02k
                EC_KEY_free(ec);
416
3.02k
417
3.02k
        if (ok < 0 && pkey != NULL) {
418
11
                EVP_PKEY_free(pkey);
419
11
                pkey = NULL;
420
11
        }
421
3.02k
422
3.02k
        return (pkey);
423
2.96k
}
424
425
int
426
es256_derive_pk(const es256_sk_t *sk, es256_pk_t *pk)
427
4.81k
{
428
4.81k
        BIGNUM          *d = NULL;
429
4.81k
        EC_KEY          *ec = NULL;
430
4.81k
        EC_POINT        *q = NULL;
431
4.81k
        const EC_GROUP  *g = NULL;
432
4.81k
        const int        nid = NID_X9_62_prime256v1;
433
4.81k
        int              ok = -1;
434
4.81k
435
4.81k
        if ((d = BN_bin2bn(sk->d, (int)sizeof(sk->d), NULL)) == NULL ||
436
4.81k
            (ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
437
4.81k
            (g = EC_KEY_get0_group(ec)) == NULL ||
438
4.81k
            (q = EC_POINT_new(g)) == NULL) {
439
65
                fido_log_debug("%s: get", __func__);
440
65
                goto fail;
441
65
        }
442
4.75k
443
4.75k
        if (EC_POINT_mul(g, q, d, NULL, NULL, NULL) == 0 ||
444
4.75k
            EC_KEY_set_public_key(ec, q) == 0 ||
445
4.75k
            es256_pk_from_EC_KEY(pk, ec) != FIDO_OK) {
446
116
                fido_log_debug("%s: set", __func__);
447
116
                goto fail;
448
116
        }
449
4.63k
450
4.63k
        ok = 0;
451
4.81k
fail:
452
4.81k
        if (d != NULL)
453
4.81k
                BN_clear_free(d);
454
4.81k
        if (q != NULL)
455
4.81k
                EC_POINT_free(q);
456
4.81k
        if (ec != NULL)
457
4.81k
                EC_KEY_free(ec);
458
4.81k
459
4.81k
        return (ok);
460
4.63k
}