Coverage Report

Created: 2021-03-26 11:35

/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
9.37k
{
16
9.37k
        if (cbor_isa_bytestring(item) == false ||
17
9.37k
            cbor_bytestring_is_definite(item) == false ||
18
9.37k
            cbor_bytestring_length(item) != xy_len) {
19
119
                fido_log_debug("%s: cbor type", __func__);
20
119
                return (-1);
21
119
        }
22
9.26k
23
9.26k
        memcpy(xy, cbor_bytestring_handle(item), xy_len);
24
9.26k
25
9.26k
        return (0);
26
9.26k
}
27
28
static int
29
decode_pubkey_point(const cbor_item_t *key, const cbor_item_t *val, void *arg)
30
24.1k
{
31
24.1k
        es256_pk_t *k = arg;
32
24.1k
33
24.1k
        if (cbor_isa_negint(key) == false ||
34
24.1k
            cbor_int_get_width(key) != CBOR_INT_8)
35
12.0k
                return (0); /* ignore */
36
12.0k
37
12.0k
        switch (cbor_get_uint8(key)) {
38
4.79k
        case 1: /* x coordinate */
39
4.79k
                return (decode_coord(val, &k->x, sizeof(k->x)));
40
4.58k
        case 2: /* y coordinate */
41
4.58k
                return (decode_coord(val, &k->y, sizeof(k->y)));
42
2.65k
        }
43
2.65k
44
2.65k
        return (0); /* ignore */
45
2.65k
}
46
47
int
48
es256_pk_decode(const cbor_item_t *item, es256_pk_t *k)
49
4.89k
{
50
4.89k
        if (cbor_isa_map(item) == false ||
51
4.89k
            cbor_map_is_definite(item) == false ||
52
4.89k
            cbor_map_iter(item, k, decode_pubkey_point) < 0) {
53
182
                fido_log_debug("%s: cbor type", __func__);
54
182
                return (-1);
55
182
        }
56
4.70k
57
4.70k
        return (0);
58
4.70k
}
59
60
cbor_item_t *
61
es256_pk_encode(const es256_pk_t *pk, int ecdh)
62
3.03k
{
63
3.03k
        cbor_item_t             *item = NULL;
64
3.03k
        struct cbor_pair         argv[5];
65
3.03k
        int                      alg;
66
3.03k
        int                      ok = -1;
67
3.03k
68
3.03k
        memset(argv, 0, sizeof(argv));
69
3.03k
70
3.03k
        if ((item = cbor_new_definite_map(5)) == NULL)
71
3.03k
                goto fail;
72
3.02k
73
3.02k
        /* kty */
74
3.02k
        if ((argv[0].key = cbor_build_uint8(1)) == NULL ||
75
3.02k
            (argv[0].value = cbor_build_uint8(2)) == NULL ||
76
3.02k
            !cbor_map_add(item, argv[0]))
77
28
                goto fail;
78
2.99k
79
2.99k
        /*
80
2.99k
         * "The COSEAlgorithmIdentifier used is -25 (ECDH-ES +
81
2.99k
         * HKDF-256) although this is NOT the algorithm actually
82
2.99k
         * used. Setting this to a different value may result in
83
2.99k
         * compatibility issues."
84
2.99k
         */
85
2.99k
        if (ecdh)
86
2.95k
                alg = COSE_ECDH_ES256;
87
2.99k
        else
88
2.99k
                alg = COSE_ES256;
89
2.99k
90
2.99k
        /* alg */
91
2.99k
        if ((argv[1].key = cbor_build_uint8(3)) == NULL ||
92
2.99k
            (argv[1].value = cbor_build_negint8((uint8_t)(-alg - 1))) == NULL ||
93
2.99k
            !cbor_map_add(item, argv[1]))
94
40
                goto fail;
95
2.95k
96
2.95k
        /* crv */
97
2.95k
        if ((argv[2].key = cbor_build_negint8(0)) == NULL ||
98
2.95k
            (argv[2].value = cbor_build_uint8(1)) == NULL ||
99
2.95k
            !cbor_map_add(item, argv[2]))
100
37
                goto fail;
101
2.91k
102
2.91k
        /* x */
103
2.91k
        if ((argv[3].key = cbor_build_negint8(1)) == NULL ||
104
2.91k
            (argv[3].value = cbor_build_bytestring(pk->x,
105
2.91k
            sizeof(pk->x))) == NULL || !cbor_map_add(item, argv[3]))
106
35
                goto fail;
107
2.88k
108
2.88k
        /* y */
109
2.88k
        if ((argv[4].key = cbor_build_negint8(2)) == NULL ||
110
2.88k
            (argv[4].value = cbor_build_bytestring(pk->y,
111
2.87k
            sizeof(pk->y))) == NULL || !cbor_map_add(item, argv[4]))
112
33
                goto fail;
113
2.85k
114
2.85k
        ok = 0;
115
3.03k
fail:
116
3.03k
        if (ok < 0) {
117
182
                if (item != NULL) {
118
173
                        cbor_decref(&item);
119
173
                        item = NULL;
120
173
                }
121
182
        }
122
3.03k
123
18.1k
        for (size_t i = 0; i < 5; i++) {
124
15.1k
                if (argv[i].key)
125
14.7k
                        cbor_decref(&argv[i].key);
126
15.1k
                if (argv[i].value)
127
14.6k
                        cbor_decref(&argv[i].value);
128
15.1k
        }
129
3.03k
130
3.03k
        return (item);
131
2.85k
}
132
133
es256_sk_t *
134
es256_sk_new(void)
135
6.31k
{
136
6.31k
        return (calloc(1, sizeof(es256_sk_t)));
137
6.31k
}
138
139
void
140
es256_sk_free(es256_sk_t **skp)
141
6.31k
{
142
6.31k
        es256_sk_t *sk;
143
6.31k
144
6.31k
        if (skp == NULL || (sk = *skp) == NULL)
145
6.31k
                return;
146
6.29k
147
6.29k
        freezero(sk, sizeof(*sk));
148
6.29k
        *skp = NULL;
149
6.29k
}
150
151
es256_pk_t *
152
es256_pk_new(void)
153
12.5k
{
154
12.5k
        return (calloc(1, sizeof(es256_pk_t)));
155
12.5k
}
156
157
void
158
es256_pk_free(es256_pk_t **pkp)
159
20.4k
{
160
20.4k
        es256_pk_t *pk;
161
20.4k
162
20.4k
        if (pkp == NULL || (pk = *pkp) == NULL)
163
20.4k
                return;
164
12.5k
165
12.5k
        freezero(pk, sizeof(*pk));
166
12.5k
        *pkp = NULL;
167
12.5k
}
168
169
int
170
es256_pk_from_ptr(es256_pk_t *pk, const void *ptr, size_t len)
171
565
{
172
565
        const uint8_t *p = ptr;
173
565
174
565
        if (len < sizeof(*pk))
175
522
                return (FIDO_ERR_INVALID_ARGUMENT);
176
43
177
43
        if (len == sizeof(*pk) + 1 && *p == 0x04)
178
1
                memcpy(pk, ++p, sizeof(*pk)); /* uncompressed format */
179
42
        else
180
42
                memcpy(pk, ptr, sizeof(*pk)); /* libfido2 x||y format */
181
43
182
43
        return (FIDO_OK);
183
43
}
184
185
int
186
es256_pk_set_x(es256_pk_t *pk, const unsigned char *x)
187
45
{
188
45
        memcpy(pk->x, x, sizeof(pk->x));
189
45
190
45
        return (0);
191
45
}
192
193
int
194
es256_pk_set_y(es256_pk_t *pk, const unsigned char *y)
195
45
{
196
45
        memcpy(pk->y, y, sizeof(pk->y));
197
45
198
45
        return (0);
199
45
}
200
201
int
202
es256_sk_create(es256_sk_t *key)
203
6.26k
{
204
6.26k
        EVP_PKEY_CTX    *pctx = NULL;
205
6.26k
        EVP_PKEY_CTX    *kctx = NULL;
206
6.26k
        EVP_PKEY        *p = NULL;
207
6.26k
        EVP_PKEY        *k = NULL;
208
6.26k
        const EC_KEY    *ec;
209
6.26k
        const BIGNUM    *d;
210
6.26k
        const int        nid = NID_X9_62_prime256v1;
211
6.26k
        int              n;
212
6.26k
        int              ok = -1;
213
6.26k
214
6.26k
        if ((pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_EC, NULL)) == NULL ||
215
6.26k
            EVP_PKEY_paramgen_init(pctx) <= 0 ||
216
6.26k
            EVP_PKEY_CTX_set_ec_paramgen_curve_nid(pctx, nid) <= 0 ||
217
6.26k
            EVP_PKEY_paramgen(pctx, &p) <= 0) {
218
91
                fido_log_debug("%s: EVP_PKEY_paramgen", __func__);
219
91
                goto fail;
220
91
        }
221
6.17k
222
6.17k
        if ((kctx = EVP_PKEY_CTX_new(p, NULL)) == NULL ||
223
6.17k
            EVP_PKEY_keygen_init(kctx) <= 0 || EVP_PKEY_keygen(kctx, &k) <= 0) {
224
83
                fido_log_debug("%s: EVP_PKEY_keygen", __func__);
225
83
                goto fail;
226
83
        }
227
6.08k
228
6.08k
        if ((ec = EVP_PKEY_get0_EC_KEY(k)) == NULL ||
229
6.08k
            (d = EC_KEY_get0_private_key(ec)) == NULL ||
230
6.08k
            (n = BN_num_bytes(d)) < 0 || (size_t)n > sizeof(key->d) ||
231
6.08k
            (n = BN_bn2bin(d, key->d)) < 0 || (size_t)n > sizeof(key->d)) {
232
81
                fido_log_debug("%s: EC_KEY_get0_private_key", __func__);
233
81
                goto fail;
234
81
        }
235
6.00k
236
6.00k
        ok = 0;
237
6.26k
fail:
238
6.26k
        if (p != NULL)
239
6.26k
                EVP_PKEY_free(p);
240
6.26k
        if (k != NULL)
241
6.26k
                EVP_PKEY_free(k);
242
6.26k
        if (pctx != NULL)
243
6.26k
                EVP_PKEY_CTX_free(pctx);
244
6.26k
        if (kctx != NULL)
245
6.26k
                EVP_PKEY_CTX_free(kctx);
246
6.26k
247
6.26k
        return (ok);
248
6.00k
}
249
250
EVP_PKEY *
251
es256_pk_to_EVP_PKEY(const es256_pk_t *k)
252
3.83k
{
253
3.83k
        BN_CTX          *bnctx = NULL;
254
3.83k
        EC_KEY          *ec = NULL;
255
3.83k
        EC_POINT        *q = NULL;
256
3.83k
        EVP_PKEY        *pkey = NULL;
257
3.83k
        BIGNUM          *x = NULL;
258
3.83k
        BIGNUM          *y = NULL;
259
3.83k
        const EC_GROUP  *g = NULL;
260
3.83k
        const int        nid = NID_X9_62_prime256v1;
261
3.83k
        int              ok = -1;
262
3.83k
263
3.83k
        if ((bnctx = BN_CTX_new()) == NULL)
264
3.83k
                goto fail;
265
3.82k
266
3.82k
        BN_CTX_start(bnctx);
267
3.82k
268
3.82k
        if ((x = BN_CTX_get(bnctx)) == NULL ||
269
3.82k
            (y = BN_CTX_get(bnctx)) == NULL)
270
3.82k
                goto fail;
271
3.79k
272
3.79k
        if (BN_bin2bn(k->x, sizeof(k->x), x) == NULL ||
273
3.79k
            BN_bin2bn(k->y, sizeof(k->y), y) == NULL) {
274
33
                fido_log_debug("%s: BN_bin2bn", __func__);
275
33
                goto fail;
276
33
        }
277
3.76k
278
3.76k
        if ((ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
279
3.76k
            (g = EC_KEY_get0_group(ec)) == NULL) {
280
31
                fido_log_debug("%s: EC_KEY init", __func__);
281
31
                goto fail;
282
31
        }
283
3.73k
284
3.73k
        if ((q = EC_POINT_new(g)) == NULL ||
285
3.73k
            EC_POINT_set_affine_coordinates_GFp(g, q, x, y, bnctx) == 0 ||
286
3.73k
            EC_KEY_set_public_key(ec, q) == 0) {
287
195
                fido_log_debug("%s: EC_KEY_set_public_key", __func__);
288
195
                goto fail;
289
195
        }
290
3.53k
291
3.53k
        if ((pkey = EVP_PKEY_new()) == NULL ||
292
3.53k
            EVP_PKEY_assign_EC_KEY(pkey, ec) == 0) {
293
28
                fido_log_debug("%s: EVP_PKEY_assign_EC_KEY", __func__);
294
28
                goto fail;
295
28
        }
296
3.50k
297
3.50k
        ec = NULL; /* at this point, ec belongs to evp */
298
3.50k
299
3.50k
        ok = 0;
300
3.83k
fail:
301
3.83k
        if (bnctx != NULL) {
302
3.82k
                BN_CTX_end(bnctx);
303
3.82k
                BN_CTX_free(bnctx);
304
3.82k
        }
305
3.83k
306
3.83k
        if (ec != NULL)
307
3.83k
                EC_KEY_free(ec);
308
3.83k
        if (q != NULL)
309
3.83k
                EC_POINT_free(q);
310
3.83k
311
3.83k
        if (ok < 0 && pkey != NULL) {
312
14
                EVP_PKEY_free(pkey);
313
14
                pkey = NULL;
314
14
        }
315
3.83k
316
3.83k
        return (pkey);
317
3.50k
}
318
319
int
320
es256_pk_from_EC_KEY(es256_pk_t *pk, const EC_KEY *ec)
321
5.89k
{
322
5.89k
        BN_CTX          *bnctx = NULL;
323
5.89k
        BIGNUM          *x = NULL;
324
5.89k
        BIGNUM          *y = NULL;
325
5.89k
        const EC_POINT  *q = NULL;
326
5.89k
        const EC_GROUP  *g = NULL;
327
5.89k
        int              ok = FIDO_ERR_INTERNAL;
328
5.89k
        int              n;
329
5.89k
330
5.89k
        if ((q = EC_KEY_get0_public_key(ec)) == NULL ||
331
5.89k
            (g = EC_KEY_get0_group(ec)) == NULL ||
332
5.89k
            (bnctx = BN_CTX_new()) == NULL)
333
5.89k
                goto fail;
334
5.83k
335
5.83k
        BN_CTX_start(bnctx);
336
5.83k
337
5.83k
        if ((x = BN_CTX_get(bnctx)) == NULL ||
338
5.83k
            (y = BN_CTX_get(bnctx)) == NULL)
339
5.83k
                goto fail;
340
5.77k
341
5.77k
        if (EC_POINT_get_affine_coordinates_GFp(g, q, x, y, bnctx) == 0 ||
342
5.77k
            (n = BN_num_bytes(x)) < 0 || (size_t)n > sizeof(pk->x) ||
343
5.77k
            (n = BN_num_bytes(y)) < 0 || (size_t)n > sizeof(pk->y)) {
344
26
                fido_log_debug("%s: EC_POINT_get_affine_coordinates_GFp",
345
26
                    __func__);
346
26
                goto fail;
347
26
        }
348
5.74k
349
5.74k
        if ((n = BN_bn2bin(x, pk->x)) < 0 || (size_t)n > sizeof(pk->x) ||
350
5.74k
            (n = BN_bn2bin(y, pk->y)) < 0 || (size_t)n > sizeof(pk->y)) {
351
62
                fido_log_debug("%s: BN_bn2bin", __func__);
352
62
                goto fail;
353
62
        }
354
5.68k
355
5.68k
        ok = FIDO_OK;
356
5.89k
fail:
357
5.89k
        if (bnctx != NULL) {
358
5.83k
                BN_CTX_end(bnctx);
359
5.83k
                BN_CTX_free(bnctx);
360
5.83k
        }
361
5.89k
362
5.89k
        return (ok);
363
5.68k
}
364
365
EVP_PKEY *
366
es256_sk_to_EVP_PKEY(const es256_sk_t *k)
367
3.45k
{
368
3.45k
        BN_CTX          *bnctx = NULL;
369
3.45k
        EC_KEY          *ec = NULL;
370
3.45k
        EVP_PKEY        *pkey = NULL;
371
3.45k
        BIGNUM          *d = NULL;
372
3.45k
        const int        nid = NID_X9_62_prime256v1;
373
3.45k
        int              ok = -1;
374
3.45k
375
3.45k
        if ((bnctx = BN_CTX_new()) == NULL)
376
3.45k
                goto fail;
377
3.44k
378
3.44k
        BN_CTX_start(bnctx);
379
3.44k
380
3.44k
        if ((d = BN_CTX_get(bnctx)) == NULL ||
381
3.44k
            BN_bin2bn(k->d, sizeof(k->d), d) == NULL) {
382
23
                fido_log_debug("%s: BN_bin2bn", __func__);
383
23
                goto fail;
384
23
        }
385
3.42k
386
3.42k
        if ((ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
387
3.42k
            EC_KEY_set_private_key(ec, d) == 0) {
388
15
                fido_log_debug("%s: EC_KEY_set_private_key", __func__);
389
15
                goto fail;
390
15
        }
391
3.40k
392
3.40k
        if ((pkey = EVP_PKEY_new()) == NULL ||
393
3.40k
            EVP_PKEY_assign_EC_KEY(pkey, ec) == 0) {
394
25
                fido_log_debug("%s: EVP_PKEY_assign_EC_KEY", __func__);
395
25
                goto fail;
396
25
        }
397
3.38k
398
3.38k
        ec = NULL; /* at this point, ec belongs to evp */
399
3.38k
400
3.38k
        ok = 0;
401
3.45k
fail:
402
3.45k
        if (bnctx != NULL) {
403
3.44k
                BN_CTX_end(bnctx);
404
3.44k
                BN_CTX_free(bnctx);
405
3.44k
        }
406
3.45k
407
3.45k
        if (ec != NULL)
408
3.45k
                EC_KEY_free(ec);
409
3.45k
410
3.45k
        if (ok < 0 && pkey != NULL) {
411
13
                EVP_PKEY_free(pkey);
412
13
                pkey = NULL;
413
13
        }
414
3.45k
415
3.45k
        return (pkey);
416
3.38k
}
417
418
int
419
es256_derive_pk(const es256_sk_t *sk, es256_pk_t *pk)
420
6.00k
{
421
6.00k
        BIGNUM          *d = NULL;
422
6.00k
        EC_KEY          *ec = NULL;
423
6.00k
        EC_POINT        *q = NULL;
424
6.00k
        const EC_GROUP  *g = NULL;
425
6.00k
        const int        nid = NID_X9_62_prime256v1;
426
6.00k
        int              ok = -1;
427
6.00k
428
6.00k
        if ((d = BN_bin2bn(sk->d, (int)sizeof(sk->d), NULL)) == NULL ||
429
6.00k
            (ec = EC_KEY_new_by_curve_name(nid)) == NULL ||
430
6.00k
            (g = EC_KEY_get0_group(ec)) == NULL ||
431
6.00k
            (q = EC_POINT_new(g)) == NULL) {
432
109
                fido_log_debug("%s: get", __func__);
433
109
                goto fail;
434
109
        }
435
5.89k
436
5.89k
        if (EC_POINT_mul(g, q, d, NULL, NULL, NULL) == 0 ||
437
5.89k
            EC_KEY_set_public_key(ec, q) == 0 ||
438
5.89k
            es256_pk_from_EC_KEY(pk, ec) != FIDO_OK) {
439
213
                fido_log_debug("%s: set", __func__);
440
213
                goto fail;
441
213
        }
442
5.68k
443
5.68k
        ok = 0;
444
6.00k
fail:
445
6.00k
        if (d != NULL)
446
6.00k
                BN_clear_free(d);
447
6.00k
        if (q != NULL)
448
6.00k
                EC_POINT_free(q);
449
6.00k
        if (ec != NULL)
450
6.00k
                EC_KEY_free(ec);
451
6.00k
452
6.00k
        return (ok);
453
5.68k
}