Coverage Report

Created: 2023-09-23 17:42

/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.
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 * SPDX-License-Identifier: BSD-2-Clause
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 */
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8
#include "fido.h"
9
10
static int
11
aes256_cbc(const fido_blob_t *key, const u_char *iv, const fido_blob_t *in,
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    fido_blob_t *out, int encrypt)
13
5.33k
{
14
5.33k
        EVP_CIPHER_CTX *ctx = NULL;
15
5.33k
        const EVP_CIPHER *cipher;
16
5.33k
        int ok = -1;
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18
5.33k
        memset(out, 0, sizeof(*out));
19
20
5.33k
        if (key->len != 32) {
21
0
                fido_log_debug("%s: invalid key len %zu", __func__, key->len);
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0
                goto fail;
23
0
        }
24
5.33k
        if (in->len > UINT_MAX || in->len % 16 || in->len == 0) {
25
129
                fido_log_debug("%s: invalid input len %zu", __func__, in->len);
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129
                goto fail;
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129
        }
28
5.20k
        out->len = in->len;
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5.20k
        if ((out->ptr = calloc(1, out->len)) == NULL) {
30
18
                fido_log_debug("%s: calloc", __func__);
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18
                goto fail;
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18
        }
33
5.18k
        if ((ctx = EVP_CIPHER_CTX_new()) == NULL ||
34
5.18k
            (cipher = EVP_aes_256_cbc()) == NULL) {
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31
                fido_log_debug("%s: EVP_CIPHER_CTX_new", __func__);
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31
                goto fail;
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31
        }
38
5.15k
        if (EVP_CipherInit(ctx, cipher, key->ptr, iv, encrypt) == 0 ||
39
5.15k
            EVP_Cipher(ctx, out->ptr, in->ptr, (u_int)out->len) < 0) {
40
43
                fido_log_debug("%s: EVP_Cipher", __func__);
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43
                goto fail;
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43
        }
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44
5.11k
        ok = 0;
45
5.33k
fail:
46
5.33k
        if (ctx != NULL)
47
5.16k
                EVP_CIPHER_CTX_free(ctx);
48
5.33k
        if (ok < 0)
49
221
                fido_blob_reset(out);
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51
5.33k
        return ok;
52
5.11k
}
53
54
static int
55
aes256_cbc_proto1(const fido_blob_t *key, const fido_blob_t *in,
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    fido_blob_t *out, int encrypt)
57
4.82k
{
58
4.82k
        u_char iv[16];
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60
4.82k
        memset(&iv, 0, sizeof(iv));
61
62
4.82k
        return aes256_cbc(key, iv, in, out, encrypt);
63
4.82k
}
64
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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)
68
555
{
69
555
        fido_blob_t key, cin, cout;
70
555
        u_char iv[16];
71
72
555
        memset(out, 0, sizeof(*out));
73
74
555
        if (secret->len != 64) {
75
0
                fido_log_debug("%s: invalid secret len %zu", __func__,
76
0
                    secret->len);
77
0
                return -1;
78
0
        }
79
555
        if (in->len < sizeof(iv)) {
80
29
                fido_log_debug("%s: invalid input len %zu", __func__, in->len);
81
29
                return -1;
82
29
        }
83
526
        if (encrypt) {
84
466
                if (fido_get_random(iv, sizeof(iv)) < 0) {
85
14
                        fido_log_debug("%s: fido_get_random", __func__);
86
14
                        return -1;
87
14
                }
88
452
                cin = *in;
89
452
        } else {
90
60
                memcpy(iv, in->ptr, sizeof(iv));
91
60
                cin.ptr = in->ptr + sizeof(iv);
92
60
                cin.len = in->len - sizeof(iv);
93
60
        }
94
512
        key.ptr = secret->ptr + 32;
95
512
        key.len = secret->len - 32;
96
512
        if (aes256_cbc(&key, iv, &cin, &cout, encrypt) < 0)
97
64
                return -1;
98
448
        if (encrypt) {
99
423
                if (cout.len > SIZE_MAX - sizeof(iv) ||
100
423
                    (out->ptr = calloc(1, sizeof(iv) + cout.len)) == NULL) {
101
11
                        fido_blob_reset(&cout);
102
11
                        return -1;
103
11
                }
104
412
                out->len = sizeof(iv) + cout.len;
105
412
                memcpy(out->ptr, iv, sizeof(iv));
106
412
                memcpy(out->ptr + sizeof(iv), cout.ptr, cout.len);
107
412
                fido_blob_reset(&cout);
108
412
        } else
109
25
                *out = cout;
110
111
437
        return 0;
112
448
}
113
114
static int
115
aes256_gcm(const fido_blob_t *key, const fido_blob_t *nonce,
116
    const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out,
117
    int encrypt)
118
1.23k
{
119
1.23k
        EVP_CIPHER_CTX *ctx = NULL;
120
1.23k
        const EVP_CIPHER *cipher;
121
1.23k
        size_t textlen;
122
1.23k
        int ok = -1;
123
124
1.23k
        memset(out, 0, sizeof(*out));
125
126
1.23k
        if (nonce->len != 12 || key->len != 32 || aad->len > UINT_MAX) {
127
0
                fido_log_debug("%s: invalid params %zu, %zu, %zu", __func__,
128
0
                    nonce->len, key->len, aad->len);
129
0
                goto fail;
130
0
        }
131
1.23k
        if (in->len > UINT_MAX || in->len > SIZE_MAX - 16 || in->len < 16) {
132
129
                fido_log_debug("%s: invalid input len %zu", __func__, in->len);
133
129
                goto fail;
134
129
        }
135
        /* add tag to (on encrypt) or trim tag from the output (on decrypt) */
136
1.10k
        out->len = encrypt ? in->len + 16 : in->len - 16;
137
1.10k
        if ((out->ptr = calloc(1, out->len)) == NULL) {
138
6
                fido_log_debug("%s: calloc", __func__);
139
6
                goto fail;
140
6
        }
141
1.10k
        if ((ctx = EVP_CIPHER_CTX_new()) == NULL ||
142
1.10k
            (cipher = EVP_aes_256_gcm()) == NULL) {
143
14
                fido_log_debug("%s: EVP_CIPHER_CTX_new", __func__);
144
14
                goto fail;
145
14
        }
146
1.08k
        if (EVP_CipherInit(ctx, cipher, key->ptr, nonce->ptr, encrypt) == 0) {
147
6
                fido_log_debug("%s: EVP_CipherInit", __func__);
148
6
                goto fail;
149
6
        }
150
151
1.08k
        if (encrypt)
152
479
                textlen = in->len;
153
603
        else {
154
603
                textlen = in->len - 16;
155
                /* point openssl at the mac tag */
156
603
                if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16,
157
603
                    in->ptr + in->len - 16) == 0) {
158
8
                        fido_log_debug("%s: EVP_CIPHER_CTX_ctrl", __func__);
159
8
                        goto fail;
160
8
                }
161
603
        }
162
        /* the last EVP_Cipher() will either compute or verify the mac tag */
163
1.07k
        if (EVP_Cipher(ctx, NULL, aad->ptr, (u_int)aad->len) < 0 ||
164
1.07k
            EVP_Cipher(ctx, out->ptr, in->ptr, (u_int)textlen) < 0 ||
165
1.07k
            EVP_Cipher(ctx, NULL, NULL, 0) < 0) {
166
278
                fido_log_debug("%s: EVP_Cipher", __func__);
167
278
                goto fail;
168
278
        }
169
796
        if (encrypt) {
170
                /* append the mac tag */
171
475
                if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16,
172
475
                    out->ptr + out->len - 16) == 0) {
173
2
                        fido_log_debug("%s: EVP_CIPHER_CTX_ctrl", __func__);
174
2
                        goto fail;
175
2
                }
176
475
        }
177
178
794
        ok = 0;
179
1.23k
fail:
180
1.23k
        if (ctx != NULL)
181
1.09k
                EVP_CIPHER_CTX_free(ctx);
182
1.23k
        if (ok < 0)
183
443
                fido_blob_reset(out);
184
185
1.23k
        return ok;
186
794
}
187
188
int
189
aes256_cbc_enc(const fido_dev_t *dev, const fido_blob_t *secret,
190
    const fido_blob_t *in, fido_blob_t *out)
191
3.16k
{
192
3.16k
        return fido_dev_get_pin_protocol(dev) == 2 ? aes256_cbc_fips(secret,
193
2.70k
            in, out, 1) : aes256_cbc_proto1(secret, in, out, 1);
194
3.16k
}
195
196
int
197
aes256_cbc_dec(const fido_dev_t *dev, const fido_blob_t *secret,
198
    const fido_blob_t *in, fido_blob_t *out)
199
2.20k
{
200
2.20k
        return fido_dev_get_pin_protocol(dev) == 2 ? aes256_cbc_fips(secret,
201
2.11k
            in, out, 0) : aes256_cbc_proto1(secret, in, out, 0);
202
2.20k
}
203
204
int
205
aes256_gcm_enc(const fido_blob_t *key, const fido_blob_t *nonce,
206
    const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out)
207
615
{
208
615
        return aes256_gcm(key, nonce, aad, in, out, 1);
209
615
}
210
211
int
212
aes256_gcm_dec(const fido_blob_t *key, const fido_blob_t *nonce,
213
    const fido_blob_t *aad, const fido_blob_t *in, fido_blob_t *out)
214
622
{
215
622
        return aes256_gcm(key, nonce, aad, in, out, 0);
216
622
}