Coverage Report

Created: 2021-07-20 18:14

/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/obj_mac.h>
9
10
#include "fido.h"
11
#include "fido/es256.h"
12
13
static int
14
decode_coord(const cbor_item_t *item, void *xy, size_t xy_len)
15
10.1k
{
16
10.1k
        if (cbor_isa_bytestring(item) == false ||
17
10.1k
            cbor_bytestring_is_definite(item) == false ||
18
10.1k
            cbor_bytestring_length(item) != xy_len) {
19
123
                fido_log_debug("%s: cbor type", __func__);
20
123
                return (-1);
21
123
        }
22
10.0k
23
10.0k
        memcpy(xy, cbor_bytestring_handle(item), xy_len);
24
10.0k
25
10.0k
        return (0);
26
10.0k
}
27
28
static int
29
decode_pubkey_point(const cbor_item_t *key, const cbor_item_t *val, void *arg)
30
26.1k
{
31
26.1k
        es256_pk_t *k = arg;
32
26.1k
33
26.1k
        if (cbor_isa_negint(key) == false ||
34
26.1k
            cbor_int_get_width(key) != CBOR_INT_8)
35
13.1k
                return (0); /* ignore */
36
13.0k
37
13.0k
        switch (cbor_get_uint8(key)) {
38
5.21k
        case 1: /* x coordinate */
39
5.21k
                return (decode_coord(val, &k->x, sizeof(k->x)));
40
4.98k
        case 2: /* y coordinate */
41
4.98k
                return (decode_coord(val, &k->y, sizeof(k->y)));
42
2.83k
        }
43
2.83k
44
2.83k
        return (0); /* ignore */
45
2.83k
}
46
47
int
48
es256_pk_decode(const cbor_item_t *item, es256_pk_t *k)
49
5.31k
{
50
5.31k
        if (cbor_isa_map(item) == false ||
51
5.31k
            cbor_map_is_definite(item) == false ||
52
5.31k
            cbor_map_iter(item, k, decode_pubkey_point) < 0) {
53
197
                fido_log_debug("%s: cbor type", __func__);
54
197
                return (-1);
55
197
        }
56
5.12k
57
5.12k
        return (0);
58
5.12k
}
59
60
cbor_item_t *
61
es256_pk_encode(const es256_pk_t *pk, int ecdh)
62
3.23k
{
63
3.23k
        cbor_item_t             *item = NULL;
64
3.23k
        struct cbor_pair         argv[5];
65
3.23k
        int                      alg;
66
3.23k
        int                      ok = -1;
67
3.23k
68
3.23k
        memset(argv, 0, sizeof(argv));
69
3.23k
70
3.23k
        if ((item = cbor_new_definite_map(5)) == NULL)
71
3.23k
                goto fail;
72
3.21k
73
3.21k
        /* kty */
74
3.21k
        if ((argv[0].key = cbor_build_uint8(1)) == NULL ||
75
3.21k
            (argv[0].value = cbor_build_uint8(2)) == NULL ||
76
3.21k
            !cbor_map_add(item, argv[0]))
77
46
                goto fail;
78
3.17k
79
3.17k
        /*
80
3.17k
         * "The COSEAlgorithmIdentifier used is -25 (ECDH-ES +
81
3.17k
         * HKDF-256) although this is NOT the algorithm actually
82
3.17k
         * used. Setting this to a different value may result in
83
3.17k
         * compatibility issues."
84
3.17k
         */
85
3.17k
        if (ecdh)
86
3.12k
                alg = COSE_ECDH_ES256;
87
3.17k
        else
88
3.17k
                alg = COSE_ES256;
89
3.17k
90
3.17k
        /* alg */
91
3.17k
        if ((argv[1].key = cbor_build_uint8(3)) == NULL ||
92
3.17k
            (argv[1].value = cbor_build_negint8((uint8_t)(-alg - 1))) == NULL ||
93
3.17k
            !cbor_map_add(item, argv[1]))
94
41
                goto fail;
95
3.13k
96
3.13k
        /* crv */
97
3.13k
        if ((argv[2].key = cbor_build_negint8(0)) == NULL ||
98
3.13k
            (argv[2].value = cbor_build_uint8(1)) == NULL ||
99
3.13k
            !cbor_map_add(item, argv[2]))
100
37
                goto fail;
101
3.09k
102
3.09k
        /* x */
103
3.09k
        if ((argv[3].key = cbor_build_negint8(1)) == NULL ||
104
3.09k
            (argv[3].value = cbor_build_bytestring(pk->x,
105
3.07k
            sizeof(pk->x))) == NULL || !cbor_map_add(item, argv[3]))
106
35
                goto fail;
107
3.05k
108
3.05k
        /* y */
109
3.05k
        if ((argv[4].key = cbor_build_negint8(2)) == NULL ||
110
3.05k
            (argv[4].value = cbor_build_bytestring(pk->y,
111
3.03k
            sizeof(pk->y))) == NULL || !cbor_map_add(item, argv[4]))
112
47
                goto fail;
113
3.01k
114
3.01k
        ok = 0;
115
3.23k
fail:
116
3.23k
        if (ok < 0) {
117
221
                if (item != NULL) {
118
206
                        cbor_decref(&item);
119
206
                        item = NULL;
120
206
                }
121
221
        }
122
3.23k
123
19.3k
        for (size_t i = 0; i < 5; i++) {
124
16.1k
                if (argv[i].key)
125
15.5k
                        cbor_decref(&argv[i].key);
126
16.1k
                if (argv[i].value)
127
15.5k
                        cbor_decref(&argv[i].value);
128
16.1k
        }
129
3.23k
130
3.23k
        return (item);
131
3.01k
}
132
133
es256_sk_t *
134
es256_sk_new(void)
135
7.26k
{
136
7.26k
        return (calloc(1, sizeof(es256_sk_t)));
137
7.26k
}
138
139
void
140
es256_sk_free(es256_sk_t **skp)
141
7.26k
{
142
7.26k
        es256_sk_t *sk;
143
7.26k
144
7.26k
        if (skp == NULL || (sk = *skp) == NULL)
145
7.26k
                return;
146
7.24k
147
7.24k
        freezero(sk, sizeof(*sk));
148
7.24k
        *skp = NULL;
149
7.24k
}
150
151
es256_pk_t *
152
es256_pk_new(void)
153
14.5k
{
154
14.5k
        return (calloc(1, sizeof(es256_pk_t)));
155
14.5k
}
156
157
void
158
es256_pk_free(es256_pk_t **pkp)
159
25.0k
{
160
25.0k
        es256_pk_t *pk;
161
25.0k
162
25.0k
        if (pkp == NULL || (pk = *pkp) == NULL)
163
25.0k
                return;
164
14.4k
165
14.4k
        freezero(pk, sizeof(*pk));
166
14.4k
        *pkp = NULL;
167
14.4k
}
168
169
int
170
es256_pk_from_ptr(es256_pk_t *pk, const void *ptr, size_t len)
171
661
{
172
661
        const uint8_t *p = ptr;
173
661
174
661
        if (len < sizeof(*pk))
175
624
                return (FIDO_ERR_INVALID_ARGUMENT);
176
37
177
37
        if (len == sizeof(*pk) + 1 && *p == 0x04)
178
1
                memcpy(pk, ++p, sizeof(*pk)); /* uncompressed format */
179
36
        else
180
36
                memcpy(pk, ptr, sizeof(*pk)); /* libfido2 x||y format */
181
37
182
37
        return (FIDO_OK);
183
37
}
184
185
int
186
es256_pk_set_x(es256_pk_t *pk, const unsigned char *x)
187
42
{
188
42
        memcpy(pk->x, x, sizeof(pk->x));
189
42
190
42
        return (0);
191
42
}
192
193
int
194
es256_pk_set_y(es256_pk_t *pk, const unsigned char *y)
195
42
{
196
42
        memcpy(pk->y, y, sizeof(pk->y));
197
42
198
42
        return (0);
199
42
}
200
201
int
202
es256_sk_create(es256_sk_t *key)
203
7.21k
{
204
7.21k
        EVP_PKEY_CTX    *pctx = NULL;
205
7.21k
        EVP_PKEY_CTX    *kctx = NULL;
206
7.21k
        EVP_PKEY        *p = NULL;
207
7.21k
        EVP_PKEY        *k = NULL;
208
7.21k
        const EC_KEY    *ec;
209
7.21k
        const BIGNUM    *d;
210
7.21k
        const int        nid = NID_X9_62_prime256v1;
211
7.21k
        int              n;
212
7.21k
        int              ok = -1;
213
7.21k
214
7.21k
        if ((pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_EC, NULL)) == NULL ||
215
7.21k
            EVP_PKEY_paramgen_init(pctx) <= 0 ||
216
7.21k
            EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, nid) <= 0 ||
217
7.21k
            EVP_PKEY_paramgen(pctx, &p) <= 0) {
218
104
                fido_log_debug("%s: EVP_PKEY_paramgen", __func__);
219
104
                goto fail;
220
104
        }
221
7.10k
222
7.10k
        if ((kctx = EVP_PKEY_CTX_new(p, NULL)) == NULL ||
223
7.10k
            EVP_PKEY_keygen_init(kctx) <= 0 || EVP_PKEY_keygen(kctx, &k) <= 0) {
224
91
                fido_log_debug("%s: EVP_PKEY_keygen", __func__);
225
91
                goto fail;
226
91
        }
227
7.01k
228
7.01k
        if ((ec = EVP_PKEY_get0_EC_KEY(k)) == NULL ||
229
7.01k
            (d = EC_KEY_get0_private_key(ec)) == NULL ||
230
7.01k
            (n = BN_num_bytes(d)) < 0 || (size_t)n > sizeof(key->d) ||
231
7.01k
            (n = BN_bn2bin(d, key->d)) < 0 || (size_t)n > sizeof(key->d)) {
232
86
                fido_log_debug("%s: EC_KEY_get0_private_key", __func__);
233
86
                goto fail;
234
86
        }
235
6.93k
236
6.93k
        ok = 0;
237
7.21k
fail:
238
7.21k
        if (p != NULL)
239
7.21k
                EVP_PKEY_free(p);
240
7.21k
        if (k != NULL)
241
7.21k
                EVP_PKEY_free(k);
242
7.21k
        if (pctx != NULL)
243
7.21k
                EVP_PKEY_CTX_free(pctx);
244
7.21k
        if (kctx != NULL)
245
7.21k
                EVP_PKEY_CTX_free(kctx);
246
7.21k
247
7.21k
        return (ok);
248
6.93k
}
249
250
EVP_PKEY *
251
es256_pk_to_EVP_PKEY(const es256_pk_t *k)
252
4.16k
{
253
4.16k
        BN_CTX          *bnctx = NULL;
254
4.16k
        EC_KEY          *ec = NULL;
255
4.16k
        EC_POINT        *q = NULL;
256
4.16k
        EVP_PKEY        *pkey = NULL;
257
4.16k
        BIGNUM          *x = NULL;
258
4.16k
        BIGNUM          *y = NULL;
259
4.16k
        const EC_GROUP  *g = NULL;
260
4.16k
        const int        nid = NID_X9_62_prime256v1;
261
4.16k
        int              ok = -1;
262
4.16k
263
4.16k
        if ((bnctx = BN_CTX_new()) == NULL)
264
4.16k
                goto fail;
265
4.14k
266
4.14k
        BN_CTX_start(bnctx);
267
4.14k
268
4.14k
        if ((x = BN_CTX_get(bnctx)) == NULL ||
269
4.14k
            (y = BN_CTX_get(bnctx)) == NULL)
270
4.14k
                goto fail;
271
4.11k
272
4.11k
        if (BN_bin2bn(k->x, sizeof(k->x), x) == NULL ||
273
4.11k
            BN_bin2bn(k->y, sizeof(k->y), y) == NULL) {
274
37
                fido_log_debug("%s: BN_bin2bn", __func__);
275
37
                goto fail;
276
37
        }
277
4.07k
278
4.07k
        if ((ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
279
4.07k
            (g = EC_KEY_get0_group(ec)) == NULL) {
280
31
                fido_log_debug("%s: EC_KEY init", __func__);
281
31
                goto fail;
282
31
        }
283
4.04k
284
4.04k
        if ((q = EC_POINT_new(g)) == NULL ||
285
4.04k
            EC_POINT_set_affine_coordinates_GFp(g, q, x, y, bnctx) == 0 ||
286
4.04k
            EC_KEY_set_public_key(ec, q) == 0) {
287
220
                fido_log_debug("%s: EC_KEY_set_public_key", __func__);
288
220
                goto fail;
289
220
        }
290
3.82k
291
3.82k
        if ((pkey = EVP_PKEY_new()) == NULL ||
292
3.82k
            EVP_PKEY_assign_EC_KEY(pkey, ec) == 0) {
293
31
                fido_log_debug("%s: EVP_PKEY_assign_EC_KEY", __func__);
294
31
                goto fail;
295
31
        }
296
3.79k
297
3.79k
        ec = NULL; /* at this point, ec belongs to evp */
298
3.79k
299
3.79k
        ok = 0;
300
4.16k
fail:
301
4.16k
        if (bnctx != NULL) {
302
4.14k
                BN_CTX_end(bnctx);
303
4.14k
                BN_CTX_free(bnctx);
304
4.14k
        }
305
4.16k
306
4.16k
        if (ec != NULL)
307
4.16k
                EC_KEY_free(ec);
308
4.16k
        if (q != NULL)
309
4.16k
                EC_POINT_free(q);
310
4.16k
311
4.16k
        if (ok < 0 && pkey != NULL) {
312
16
                EVP_PKEY_free(pkey);
313
16
                pkey = NULL;
314
16
        }
315
4.16k
316
4.16k
        return (pkey);
317
3.79k
}
318
319
int
320
es256_pk_from_EC_KEY(es256_pk_t *pk, const EC_KEY *ec)
321
6.79k
{
322
6.79k
        BN_CTX          *bnctx = NULL;
323
6.79k
        BIGNUM          *x = NULL;
324
6.79k
        BIGNUM          *y = NULL;
325
6.79k
        const EC_POINT  *q = NULL;
326
6.79k
        const EC_GROUP  *g = NULL;
327
6.79k
        int              ok = FIDO_ERR_INTERNAL;
328
6.79k
        int              n;
329
6.79k
330
6.79k
        if ((q = EC_KEY_get0_public_key(ec)) == NULL ||
331
6.79k
            (g = EC_KEY_get0_group(ec)) == NULL ||
332
6.79k
            (bnctx = BN_CTX_new()) == NULL)
333
6.79k
                goto fail;
334
6.72k
335
6.72k
        BN_CTX_start(bnctx);
336
6.72k
337
6.72k
        if ((x = BN_CTX_get(bnctx)) == NULL ||
338
6.72k
            (y = BN_CTX_get(bnctx)) == NULL)
339
6.72k
                goto fail;
340
6.65k
341
6.65k
        if (EC_POINT_get_affine_coordinates_GFp(g, q, x, y, bnctx) == 0 ||
342
6.65k
            (n = BN_num_bytes(x)) < 0 || (size_t)n > sizeof(pk->x) ||
343
6.65k
            (n = BN_num_bytes(y)) < 0 || (size_t)n > sizeof(pk->y)) {
344
33
                fido_log_debug("%s: EC_POINT_get_affine_coordinates_GFp",
345
33
                    __func__);
346
33
                goto fail;
347
33
        }
348
6.62k
349
6.62k
        if ((n = BN_bn2bin(x, pk->x)) < 0 || (size_t)n > sizeof(pk->x) ||
350
6.62k
            (n = BN_bn2bin(y, pk->y)) < 0 || (size_t)n > sizeof(pk->y)) {
351
65
                fido_log_debug("%s: BN_bn2bin", __func__);
352
65
                goto fail;
353
65
        }
354
6.55k
355
6.55k
        ok = FIDO_OK;
356
6.79k
fail:
357
6.79k
        if (bnctx != NULL) {
358
6.72k
                BN_CTX_end(bnctx);
359
6.72k
                BN_CTX_free(bnctx);
360
6.72k
        }
361
6.79k
362
6.79k
        return (ok);
363
6.55k
}
364
365
EVP_PKEY *
366
es256_sk_to_EVP_PKEY(const es256_sk_t *k)
367
3.75k
{
368
3.75k
        BN_CTX          *bnctx = NULL;
369
3.75k
        EC_KEY          *ec = NULL;
370
3.75k
        EVP_PKEY        *pkey = NULL;
371
3.75k
        BIGNUM          *d = NULL;
372
3.75k
        const int        nid = NID_X9_62_prime256v1;
373
3.75k
        int              ok = -1;
374
3.75k
375
3.75k
        if ((bnctx = BN_CTX_new()) == NULL)
376
3.75k
                goto fail;
377
3.74k
378
3.74k
        BN_CTX_start(bnctx);
379
3.74k
380
3.74k
        if ((d = BN_CTX_get(bnctx)) == NULL ||
381
3.74k
            BN_bin2bn(k->d, sizeof(k->d), d) == NULL) {
382
29
                fido_log_debug("%s: BN_bin2bn", __func__);
383
29
                goto fail;
384
29
        }
385
3.71k
386
3.71k
        if ((ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
387
3.71k
            EC_KEY_set_private_key(ec, d) == 0) {
388
17
                fido_log_debug("%s: EC_KEY_set_private_key", __func__);
389
17
                goto fail;
390
17
        }
391
3.69k
392
3.69k
        if ((pkey = EVP_PKEY_new()) == NULL ||
393
3.69k
            EVP_PKEY_assign_EC_KEY(pkey, ec) == 0) {
394
28
                fido_log_debug("%s: EVP_PKEY_assign_EC_KEY", __func__);
395
28
                goto fail;
396
28
        }
397
3.66k
398
3.66k
        ec = NULL; /* at this point, ec belongs to evp */
399
3.66k
400
3.66k
        ok = 0;
401
3.75k
fail:
402
3.75k
        if (bnctx != NULL) {
403
3.74k
                BN_CTX_end(bnctx);
404
3.74k
                BN_CTX_free(bnctx);
405
3.74k
        }
406
3.75k
407
3.75k
        if (ec != NULL)
408
3.75k
                EC_KEY_free(ec);
409
3.75k
410
3.75k
        if (ok < 0 && pkey != NULL) {
411
13
                EVP_PKEY_free(pkey);
412
13
                pkey = NULL;
413
13
        }
414
3.75k
415
3.75k
        return (pkey);
416
3.66k
}
417
418
int
419
es256_derive_pk(const es256_sk_t *sk, es256_pk_t *pk)
420
6.93k
{
421
6.93k
        BIGNUM          *d = NULL;
422
6.93k
        EC_KEY          *ec = NULL;
423
6.93k
        EC_POINT        *q = NULL;
424
6.93k
        const EC_GROUP  *g = NULL;
425
6.93k
        const int        nid = NID_X9_62_prime256v1;
426
6.93k
        int              ok = -1;
427
6.93k
428
6.93k
        if ((d = BN_bin2bn(sk->d, (int)sizeof(sk->d), NULL)) == NULL ||
429
6.93k
            (ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
430
6.93k
            (g = EC_KEY_get0_group(ec)) == NULL ||
431
6.93k
            (q = EC_POINT_new(g)) == NULL) {
432
136
                fido_log_debug("%s: get", __func__);
433
136
                goto fail;
434
136
        }
435
6.79k
436
6.79k
        if (EC_POINT_mul(g, q, d, NULL, NULL, NULL) == 0 ||
437
6.79k
            EC_KEY_set_public_key(ec, q) == 0 ||
438
6.79k
            es256_pk_from_EC_KEY(pk, ec) != FIDO_OK) {
439
235
                fido_log_debug("%s: set", __func__);
440
235
                goto fail;
441
235
        }
442
6.55k
443
6.55k
        ok = 0;
444
6.93k
fail:
445
6.93k
        if (d != NULL)
446
6.93k
                BN_clear_free(d);
447
6.93k
        if (q != NULL)
448
6.93k
                EC_POINT_free(q);
449
6.93k
        if (ec != NULL)
450
6.93k
                EC_KEY_free(ec);
451
6.93k
452
6.93k
        return (ok);
453
6.55k
}