Coverage Report

Created: 2021-10-21 13:35

/libfido2/src/rs256.c
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Source (jump to first uncovered line)
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/*
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 * Copyright (c) 2018-2021 Yubico AB. All rights reserved.
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 * Use of this source code is governed by a BSD-style
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 * license that can be found in the LICENSE file.
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 */
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#include <openssl/bn.h>
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#include <openssl/rsa.h>
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#include <openssl/obj_mac.h>
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11
#include "fido.h"
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#include "fido/rs256.h"
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#if defined(LIBRESSL_VERSION_NUMBER)
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static EVP_MD *
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rs256_get_EVP_MD(void)
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{
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        const EVP_MD *from;
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        EVP_MD *to = NULL;
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        if ((from = EVP_sha256()) != NULL && (to = malloc(sizeof(*to))) != NULL)
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                memcpy(to, from, sizeof(*to));
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        return (to);
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}
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static void
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rs256_free_EVP_MD(EVP_MD *md)
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{
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        freezero(md, sizeof(*md));
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}
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#elif OPENSSL_VERSION_NUMBER >= 0x30000000
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static EVP_MD *
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rs256_get_EVP_MD(void)
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{
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        return (EVP_MD_fetch(NULL, "SHA2-256", NULL));
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}
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static void
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rs256_free_EVP_MD(EVP_MD *md)
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{
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        EVP_MD_free(md);
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}
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#else
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static EVP_MD *
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rs256_get_EVP_MD(void)
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135
{
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135
        const EVP_MD *md;
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135
        if ((md = EVP_sha256()) == NULL)
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135
                return (NULL);
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130
        return (EVP_MD_meth_dup(md));
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130
}
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static void
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rs256_free_EVP_MD(EVP_MD *md)
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136
{
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136
        EVP_MD_meth_free(md);
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136
}
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#endif /* LIBRESSL_VERSION_NUMBER */
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static int
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decode_bignum(const cbor_item_t *item, void *ptr, size_t len)
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411
{
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411
        if (cbor_isa_bytestring(item) == false ||
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411
            cbor_bytestring_is_definite(item) == false ||
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411
            cbor_bytestring_length(item) != len) {
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1
                fido_log_debug("%s: cbor type", __func__);
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1
                return (-1);
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1
        }
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73
410
        memcpy(ptr, cbor_bytestring_handle(item), len);
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410
        return (0);
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410
}
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static int
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decode_rsa_pubkey(const cbor_item_t *key, const cbor_item_t *val, void *arg)
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836
{
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836
        rs256_pk_t *k = arg;
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836
        if (cbor_isa_negint(key) == false ||
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836
            cbor_int_get_width(key) != CBOR_INT_8)
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419
                return (0); /* ignore */
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417
        switch (cbor_get_uint8(key)) {
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209
        case 0: /* modulus */
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209
                return (decode_bignum(val, &k->n, sizeof(k->n)));
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202
        case 1: /* public exponent */
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202
                return (decode_bignum(val, &k->e, sizeof(k->e)));
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6
        }
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6
        return (0); /* ignore */
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6
}
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int
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rs256_pk_decode(const cbor_item_t *item, rs256_pk_t *k)
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211
{
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        if (cbor_isa_map(item) == false ||
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211
            cbor_map_is_definite(item) == false ||
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211
            cbor_map_iter(item, k, decode_rsa_pubkey) < 0) {
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3
                fido_log_debug("%s: cbor type", __func__);
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3
                return (-1);
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3
        }
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107
208
        return (0);
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208
}
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rs256_pk_t *
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rs256_pk_new(void)
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749
{
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749
        return (calloc(1, sizeof(rs256_pk_t)));
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749
}
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void
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rs256_pk_free(rs256_pk_t **pkp)
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2.59k
{
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2.59k
        rs256_pk_t *pk;
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2.59k
        if (pkp == NULL || (pk = *pkp) == NULL)
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2.59k
                return;
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746
        freezero(pk, sizeof(*pk));
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746
        *pkp = NULL;
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746
}
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128
int
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rs256_pk_from_ptr(rs256_pk_t *pk, const void *ptr, size_t len)
130
396
{
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396
        if (len < sizeof(*pk))
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349
                return (FIDO_ERR_INVALID_ARGUMENT);
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134
47
        memcpy(pk, ptr, sizeof(*pk));
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136
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        return (FIDO_OK);
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47
}
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EVP_PKEY *
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rs256_pk_to_EVP_PKEY(const rs256_pk_t *k)
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559
{
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559
        RSA             *rsa = NULL;
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559
        EVP_PKEY        *pkey = NULL;
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559
        BIGNUM          *n = NULL;
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559
        BIGNUM          *e = NULL;
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559
        int              ok = -1;
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148
559
        if ((n = BN_new()) == NULL || (e = BN_new()) == NULL)
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559
                goto fail;
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151
535
        if (BN_bin2bn(k->n, sizeof(k->n), n) == NULL ||
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535
            BN_bin2bn(k->e, sizeof(k->e), e) == NULL) {
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14
                fido_log_debug("%s: BN_bin2bn", __func__);
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14
                goto fail;
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14
        }
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157
521
        if ((rsa = RSA_new()) == NULL || RSA_set0_key(rsa, n, e, NULL) == 0) {
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16
                fido_log_debug("%s: RSA_set0_key", __func__);
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16
                goto fail;
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16
        }
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162
        /* at this point, n and e belong to rsa */
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505
        n = NULL;
164
505
        e = NULL;
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166
505
        if ((pkey = EVP_PKEY_new()) == NULL ||
167
505
            EVP_PKEY_assign_RSA(pkey, rsa) == 0) {
168
18
                fido_log_debug("%s: EVP_PKEY_assign_RSA", __func__);
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18
                goto fail;
170
18
        }
171
172
487
        rsa = NULL; /* at this point, rsa belongs to evp */
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174
487
        ok = 0;
175
559
fail:
176
559
        if (n != NULL)
177
559
                BN_free(n);
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559
        if (e != NULL)
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559
                BN_free(e);
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559
        if (rsa != NULL)
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559
                RSA_free(rsa);
182
559
        if (ok < 0 && pkey != NULL) {
183
7
                EVP_PKEY_free(pkey);
184
7
                pkey = NULL;
185
7
        }
186
187
559
        return (pkey);
188
487
}
189
190
int
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rs256_pk_from_RSA(rs256_pk_t *pk, const RSA *rsa)
192
350
{
193
350
        const BIGNUM    *n = NULL;
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350
        const BIGNUM    *e = NULL;
195
350
        const BIGNUM    *d = NULL;
196
350
        int              k;
197
198
350
        if (RSA_bits(rsa) != 2048) {
199
320
                fido_log_debug("%s: invalid key length", __func__);
200
320
                return (FIDO_ERR_INVALID_ARGUMENT);
201
320
        }
202
203
30
        RSA_get0_key(rsa, &n, &e, &d);
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205
30
        if (n == NULL || e == NULL) {
206
0
                fido_log_debug("%s: RSA_get0_key", __func__);
207
0
                return (FIDO_ERR_INTERNAL);
208
0
        }
209
210
30
        if ((k = BN_num_bytes(n)) < 0 || (size_t)k > sizeof(pk->n) ||
211
30
            (k = BN_num_bytes(e)) < 0 || (size_t)k > sizeof(pk->e)) {
212
0
                fido_log_debug("%s: invalid key", __func__);
213
0
                return (FIDO_ERR_INTERNAL);
214
0
        }
215
216
30
        if ((k = BN_bn2bin(n, pk->n)) < 0 || (size_t)k > sizeof(pk->n) ||
217
30
            (k = BN_bn2bin(e, pk->e)) < 0 || (size_t)k > sizeof(pk->e)) {
218
5
                fido_log_debug("%s: BN_bn2bin", __func__);
219
5
                return (FIDO_ERR_INTERNAL);
220
5
        }
221
222
25
        return (FIDO_OK);
223
25
}
224
225
int
226
rs256_pk_from_EVP_PKEY(rs256_pk_t *pk, const EVP_PKEY *pkey)
227
350
{
228
350
        RSA *rsa;
229
230
350
        if (EVP_PKEY_base_id(pkey) != EVP_PKEY_RSA ||
231
350
            (rsa = EVP_PKEY_get0(pkey)) == NULL)
232
350
                return (FIDO_ERR_INVALID_ARGUMENT);
233
234
350
        return (rs256_pk_from_RSA(pk, rsa));
235
350
}
236
237
int
238
rs256_verify_sig(const fido_blob_t *dgst, EVP_PKEY *pkey,
239
    const fido_blob_t *sig)
240
136
{
241
136
        EVP_PKEY_CTX    *pctx = NULL;
242
136
        EVP_MD          *md = NULL;
243
136
        int              ok = -1;
244
245
136
        if (EVP_PKEY_base_id(pkey) != EVP_PKEY_RSA) {
246
1
                fido_log_debug("%s: EVP_PKEY_base_id", __func__);
247
1
                goto fail;
248
1
        }
249
250
135
        if ((md = rs256_get_EVP_MD()) == NULL) {
251
5
                fido_log_debug("%s: rs256_get_EVP_MD", __func__);
252
5
                goto fail;
253
5
        }
254
255
130
        if ((pctx = EVP_PKEY_CTX_new(pkey, NULL)) == NULL ||
256
130
            EVP_PKEY_verify_init(pctx) != 1 ||
257
130
            EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PADDING) != 1 ||
258
130
            EVP_PKEY_CTX_set_signature_md(pctx, md) != 1) {
259
15
                fido_log_debug("%s: EVP_PKEY_CTX", __func__);
260
15
                goto fail;
261
15
        }
262
263
115
        if (EVP_PKEY_verify(pctx, sig->ptr, sig->len, dgst->ptr,
264
115
            dgst->len) != 1) {
265
115
                fido_log_debug("%s: EVP_PKEY_verify", __func__);
266
115
                goto fail;
267
115
        }
268
269
0
        ok = 0;
270
136
fail:
271
136
        EVP_PKEY_CTX_free(pctx);
272
136
        rs256_free_EVP_MD(md);
273
274
136
        return (ok);
275
0
}
276
277
int
278
rs256_pk_verify_sig(const fido_blob_t *dgst, const rs256_pk_t *pk,
279
    const fido_blob_t *sig)
280
163
{
281
163
        EVP_PKEY        *pkey;
282
163
        int              ok = -1;
283
284
163
        if ((pkey = rs256_pk_to_EVP_PKEY(pk)) == NULL ||
285
163
            rs256_verify_sig(dgst, pkey, sig) < 0) {
286
163
                fido_log_debug("%s: rs256_verify_sig", __func__);
287
163
                goto fail;
288
163
        }
289
290
0
        ok = 0;
291
163
fail:
292
163
        EVP_PKEY_free(pkey);
293
294
163
        return (ok);
295
0
}