Coverage Report

Created: 2021-10-21 13:35

/libfido2/src/aes256.c
Line
Count
Source (jump to first uncovered line)
1
/*
2
 * Copyright (c) 2021 Yubico AB. All rights reserved.
3
 * Use of this source code is governed by a BSD-style
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 * license that can be found in the LICENSE file.
5
 */
6
7
#include "fido.h"
8
9
static int
10
aes256_cbc(const fido_blob_t *key, const u_char *iv, const fido_blob_t *in,
11
    fido_blob_t *out, int encrypt)
12
5.81k
{
13
5.81k
        EVP_CIPHER_CTX *ctx = NULL;
14
5.81k
        const EVP_CIPHER *cipher;
15
5.81k
        int ok = -1;
16
17
5.81k
        memset(out, 0, sizeof(*out));
18
19
5.81k
        if (key->len != 32) {
20
0
                fido_log_debug("%s: invalid key len %zu", __func__, key->len);
21
0
                goto fail;
22
0
        }
23
5.81k
        if (in->len > UINT_MAX || in->len % 16 || in->len == 0) {
24
100
                fido_log_debug("%s: invalid input len %zu", __func__, in->len);
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100
                goto fail;
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100
        }
27
5.71k
        out->len = in->len;
28
5.71k
        if ((out->ptr = calloc(1, out->len)) == NULL) {
29
18
                fido_log_debug("%s: calloc", __func__);
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18
                goto fail;
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18
        }
32
5.69k
        if ((ctx = EVP_CIPHER_CTX_new()) == NULL ||
33
5.69k
            (cipher = EVP_aes_256_cbc()) == NULL) {
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39
                fido_log_debug("%s: EVP_CIPHER_CTX_new", __func__);
35
39
                goto fail;
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39
        }
37
5.65k
        if (EVP_CipherInit(ctx, cipher, key->ptr, iv, encrypt) == 0 ||
38
5.65k
            EVP_Cipher(ctx, out->ptr, in->ptr, (u_int)out->len) < 0) {
39
27
                fido_log_debug("%s: EVP_Cipher", __func__);
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27
                goto fail;
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27
        }
42
43
5.63k
        ok = 0;
44
5.81k
fail:
45
5.81k
        if (ctx != NULL)
46
5.81k
                EVP_CIPHER_CTX_free(ctx);
47
5.81k
        if (ok < 0)
48
184
                fido_blob_reset(out);
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50
5.81k
        return ok;
51
5.63k
}
52
53
static int
54
aes256_cbc_proto1(const fido_blob_t *key, const fido_blob_t *in,
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    fido_blob_t *out, int encrypt)
56
5.51k
{
57
5.51k
        u_char iv[16];
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59
5.51k
        memset(&iv, 0, sizeof(iv));
60
61
5.51k
        return aes256_cbc(key, iv, in, out, encrypt);
62
5.51k
}
63
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static int
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aes256_cbc_fips(const fido_blob_t *secret, const fido_blob_t *in,
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    fido_blob_t *out, int encrypt)
67
320
{
68
320
        fido_blob_t key, cin, cout;
69
320
        u_char iv[16];
70
71
320
        memset(out, 0, sizeof(*out));
72
73
320
        if (secret->len != 64) {
74
0
                fido_log_debug("%s: invalid secret len %zu", __func__,
75
0
                    secret->len);
76
0
                return -1;
77
0
        }
78
320
        if (in->len < sizeof(iv)) {
79
21
                fido_log_debug("%s: invalid input len %zu", __func__, in->len);
80
21
                return -1;
81
21
        }
82
299
        if (encrypt) {
83
264
                if (fido_get_random(iv, sizeof(iv)) < 0) {
84
0
                        fido_log_debug("%s: fido_get_random", __func__);
85
0
                        return -1;
86
0
                }
87
264
                cin = *in;
88
264
        } else {
89
35
                memcpy(iv, in->ptr, sizeof(iv));
90
35
                cin.ptr = in->ptr + sizeof(iv);
91
35
                cin.len = in->len - sizeof(iv);
92
35
        }
93
299
        key.ptr = secret->ptr + 32;
94
299
        key.len = secret->len - 32;
95
299
        if (aes256_cbc(&key, iv, &cin, &cout, encrypt) < 0)
96
35
                return -1;
97
264
        if (encrypt) {
98
251
                if (cout.len > SIZE_MAX - sizeof(iv) ||
99
251
                    (out->ptr = calloc(1, sizeof(iv) + cout.len)) == NULL) {
100
6
                        fido_blob_reset(&cout);
101
6
                        return -1;
102
6
                }
103
245
                out->len = sizeof(iv) + cout.len;
104
245
                memcpy(out->ptr, iv, sizeof(iv));
105
245
                memcpy(out->ptr + sizeof(iv), cout.ptr, cout.len);
106
245
                fido_blob_reset(&cout);
107
245
        } else
108
13
                *out = cout;
109
110
264
        return 0;
111
264
}
112
113
static int
114
aes256_gcm(const fido_blob_t *key, const fido_blob_t *nonce,
115
    const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out,
116
    int encrypt)
117
1.01k
{
118
1.01k
        EVP_CIPHER_CTX *ctx = NULL;
119
1.01k
        const EVP_CIPHER *cipher;
120
1.01k
        size_t textlen;
121
1.01k
        int ok = -1;
122
123
1.01k
        memset(out, 0, sizeof(*out));
124
125
1.01k
        if (nonce->len != 12 || key->len != 32 || aad->len > UINT_MAX) {
126
0
                fido_log_debug("%s: invalid params %zu, %zu, %zu", __func__,
127
0
                    nonce->len, key->len, aad->len);
128
0
                goto fail;
129
0
        }
130
1.01k
        if (in->len > UINT_MAX || in->len > SIZE_MAX - 16 || in->len < 16) {
131
150
                fido_log_debug("%s: invalid input len %zu", __func__, in->len);
132
150
                goto fail;
133
150
        }
134
        /* add tag to (on encrypt) or trim tag from the output (on decrypt) */
135
864
        out->len = encrypt ? in->len + 16 : in->len - 16;
136
864
        if ((out->ptr = calloc(1, out->len)) == NULL) {
137
4
                fido_log_debug("%s: calloc", __func__);
138
4
                goto fail;
139
4
        }
140
860
        if ((ctx = EVP_CIPHER_CTX_new()) == NULL ||
141
860
            (cipher = EVP_aes_256_gcm()) == NULL) {
142
8
                fido_log_debug("%s: EVP_CIPHER_CTX_new", __func__);
143
8
                goto fail;
144
8
        }
145
852
        if (EVP_CipherInit(ctx, cipher, key->ptr, nonce->ptr, encrypt) == 0) {
146
5
                fido_log_debug("%s: EVP_CipherInit", __func__);
147
5
                goto fail;
148
5
        }
149
150
847
        if (encrypt)
151
515
                textlen = in->len;
152
332
        else {
153
332
                textlen = in->len - 16;
154
                /* point openssl at the mac tag */
155
332
                if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16,
156
332
                    in->ptr + in->len - 16) == 0) {
157
2
                        fido_log_debug("%s: EVP_CIPHER_CTX_ctrl", __func__);
158
2
                        goto fail;
159
2
                }
160
845
        }
161
        /* the last EVP_Cipher() will either compute or verify the mac tag */
162
845
        if (EVP_Cipher(ctx, NULL, aad->ptr, (u_int)aad->len) < 0 ||
163
845
            EVP_Cipher(ctx, out->ptr, in->ptr, (u_int)textlen) < 0 ||
164
845
            EVP_Cipher(ctx, NULL, NULL, 0) < 0) {
165
44
                fido_log_debug("%s: EVP_Cipher", __func__);
166
44
                goto fail;
167
44
        }
168
801
        if (encrypt) {
169
                /* append the mac tag */
170
506
                if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16,
171
506
                    out->ptr + out->len - 16) == 0) {
172
2
                        fido_log_debug("%s: EVP_CIPHER_CTX_ctrl", __func__);
173
2
                        goto fail;
174
2
                }
175
799
        }
176
177
799
        ok = 0;
178
1.01k
fail:
179
1.01k
        if (ctx != NULL)
180
1.01k
                EVP_CIPHER_CTX_free(ctx);
181
1.01k
        if (ok < 0)
182
215
                fido_blob_reset(out);
183
184
1.01k
        return ok;
185
799
}
186
187
int
188
aes256_cbc_enc(const fido_dev_t *dev, const fido_blob_t *secret,
189
    const fido_blob_t *in, fido_blob_t *out)
190
3.32k
{
191
3.32k
        return fido_dev_get_pin_protocol(dev) == 2 ? aes256_cbc_fips(secret,
192
3.05k
            in, out, 1) : aes256_cbc_proto1(secret, in, out, 1);
193
3.32k
}
194
195
int
196
aes256_cbc_dec(const fido_dev_t *dev, const fido_blob_t *secret,
197
    const fido_blob_t *in, fido_blob_t *out)
198
2.51k
{
199
2.51k
        return fido_dev_get_pin_protocol(dev) == 2 ? aes256_cbc_fips(secret,
200
2.45k
            in, out, 0) : aes256_cbc_proto1(secret, in, out, 0);
201
2.51k
}
202
203
int
204
aes256_gcm_enc(const fido_blob_t *key, const fido_blob_t *nonce,
205
    const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out)
206
675
{
207
675
        return aes256_gcm(key, nonce, aad, in, out, 1);
208
675
}
209
210
int
211
aes256_gcm_dec(const fido_blob_t *key, const fido_blob_t *nonce,
212
    const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out)
213
339
{
214
339
        return aes256_gcm(key, nonce, aad, in, out, 0);
215
339
}