1 /*
2 * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 */
6
7 #include <arch_helpers.h>
8 #include <crypto_driver.h>
9 #include <crypto_mod.h>
10 #include <debug.h>
11 #include <mbedtls_common.h>
12 #include <platform_def.h>
13 #include <rsa.h>
14 #include <sbrom_bsv_api.h>
15 #include <secureboot_base_func.h>
16 #include <secureboot_gen_defs.h>
17 #include <stddef.h>
18 #include <string.h>
19 #include <util.h>
20 #include <utils.h>
21
22 #include <mbedtls/oid.h>
23
24 #define LIB_NAME "CryptoCell SBROM"
25 #define RSA_SALT_LEN 32
26 #define RSA_EXPONENT 65537
27
28 /*
29 * AlgorithmIdentifier ::= SEQUENCE {
30 * algorithm OBJECT IDENTIFIER,
31 * parameters ANY DEFINED BY algorithm OPTIONAL
32 * }
33 *
34 * SubjectPublicKeyInfo ::= SEQUENCE {
35 * algorithm AlgorithmIdentifier,
36 * subjectPublicKey BIT STRING
37 * }
38 *
39 * DigestInfo ::= SEQUENCE {
40 * digestAlgorithm AlgorithmIdentifier,
41 * digest OCTET STRING
42 * }
43 *
44 * RSASSA-PSS-params ::= SEQUENCE {
45 * hashAlgorithm [0] HashAlgorithm,
46 * maskGenAlgorithm [1] MaskGenAlgorithm,
47 * saltLength [2] INTEGER,
48 * trailerField [3] TrailerField DEFAULT trailerFieldBC
49 * }
50 */
51
52 /*
53 * Initialize the library and export the descriptor
54 */
init(void)55 static void init(void)
56 {
57 CCError_t ret;
58 uint32_t lcs;
59
60 /* Initialize CC SBROM */
61 ret = CC_BsvSbromInit((uintptr_t)PLAT_CRYPTOCELL_BASE);
62 if (ret != CC_OK) {
63 ERROR("CryptoCell CC_BsvSbromInit() error %x\n", ret);
64 panic();
65 }
66
67 /* Initialize lifecycle state */
68 ret = CC_BsvLcsGetAndInit((uintptr_t)PLAT_CRYPTOCELL_BASE, &lcs);
69 if (ret != CC_OK) {
70 ERROR("CryptoCell CC_BsvLcsGetAndInit() error %x\n", ret);
71 panic();
72 }
73
74 /* If the lifecyclestate is `SD`, then stop further execution */
75 if (lcs == CC_BSV_SECURITY_DISABLED_LCS) {
76 ERROR("CryptoCell LCS is security-disabled\n");
77 panic();
78 }
79 }
80
81 /*
82 * Verify a signature.
83 *
84 * Parameters are passed using the DER encoding format following the ASN.1
85 * structures detailed above.
86 */
verify_signature(void * data_ptr,unsigned int data_len,void * sig_ptr,unsigned int sig_len,void * sig_alg,unsigned int sig_alg_len,void * pk_ptr,unsigned int pk_len)87 static int verify_signature(void *data_ptr, unsigned int data_len,
88 void *sig_ptr, unsigned int sig_len,
89 void *sig_alg, unsigned int sig_alg_len,
90 void *pk_ptr, unsigned int pk_len)
91 {
92 CCError_t error;
93 CCSbNParams_t pk;
94 CCSbSignature_t signature;
95 int rc, exp;
96 mbedtls_asn1_buf sig_oid, alg_oid, params;
97 mbedtls_md_type_t md_alg;
98 mbedtls_pk_type_t pk_alg;
99 mbedtls_pk_rsassa_pss_options pss_opts;
100 size_t len;
101 uint8_t *p, *end;
102 /* Temp buf to store the public key modulo (N) in LE format */
103 uint32_t RevN[SB_RSA_MOD_SIZE_IN_WORDS];
104
105 /* Verify the signature algorithm */
106 /* Get pointers to signature OID and parameters */
107 p = sig_alg;
108 end = p + sig_alg_len;
109 rc = mbedtls_asn1_get_alg(&p, end, &sig_oid, ¶ms);
110 if (rc != 0)
111 return CRYPTO_ERR_SIGNATURE;
112
113 /* Get the actual signature algorithm (MD + PK) */
114 rc = mbedtls_oid_get_sig_alg(&sig_oid, &md_alg, &pk_alg);
115 if (rc != 0)
116 return CRYPTO_ERR_SIGNATURE;
117
118 /* The CryptoCell only supports RSASSA-PSS signature */
119 if (pk_alg != MBEDTLS_PK_RSASSA_PSS || md_alg != MBEDTLS_MD_NONE)
120 return CRYPTO_ERR_SIGNATURE;
121
122 /* Verify the RSASSA-PSS params */
123 /* The trailer field is verified to be 0xBC internally by this API */
124 rc = mbedtls_x509_get_rsassa_pss_params(¶ms, &md_alg,
125 &pss_opts.mgf1_hash_id,
126 &pss_opts.expected_salt_len);
127 if (rc != 0)
128 return CRYPTO_ERR_SIGNATURE;
129
130 /* The CryptoCell only supports SHA256 as hash algorithm */
131 if (md_alg != MBEDTLS_MD_SHA256 || pss_opts.mgf1_hash_id != MBEDTLS_MD_SHA256)
132 return CRYPTO_ERR_SIGNATURE;
133
134 if (pss_opts.expected_salt_len != RSA_SALT_LEN)
135 return CRYPTO_ERR_SIGNATURE;
136
137 /* Parse the public key */
138 p = pk_ptr;
139 end = p + pk_len;
140 rc = mbedtls_asn1_get_tag(&p, end, &len,
141 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE);
142 if (rc != 0)
143 return CRYPTO_ERR_SIGNATURE;
144
145 end = p + len;
146 rc = mbedtls_asn1_get_alg_null(&p, end, &alg_oid);
147 if (rc != 0)
148 return CRYPTO_ERR_SIGNATURE;
149
150 if (mbedtls_oid_get_pk_alg(&alg_oid, &pk_alg) != 0)
151 return CRYPTO_ERR_SIGNATURE;
152
153 if (pk_alg != MBEDTLS_PK_RSA)
154 return CRYPTO_ERR_SIGNATURE;
155
156 rc = mbedtls_asn1_get_bitstring_null(&p, end, &len);
157 if (rc != 0)
158 return CRYPTO_ERR_SIGNATURE;
159
160 rc = mbedtls_asn1_get_tag(&p, end, &len,
161 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE);
162 if (rc != 0)
163 return CRYPTO_ERR_SIGNATURE;
164
165 rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_INTEGER);
166 if (rc != 0)
167 return CRYPTO_ERR_SIGNATURE;
168
169 if (*p == 0) {
170 p++; len--;
171 }
172 if (len != RSA_MOD_SIZE_IN_BYTES || ((p + len) > end))
173 return CRYPTO_ERR_SIGNATURE;
174
175 /*
176 * The CCSbVerifySignature() API expects N and Np in BE format and
177 * the signature in LE format. Copy N from certificate.
178 */
179 memcpy(pk.N, p, RSA_MOD_SIZE_IN_BYTES);
180
181 /* Verify the RSA exponent */
182 p += len;
183 rc = mbedtls_asn1_get_int(&p, end, &exp);
184 if (rc != 0)
185 return CRYPTO_ERR_SIGNATURE;
186
187 if (exp != RSA_EXPONENT)
188 return CRYPTO_ERR_SIGNATURE;
189
190 /*
191 * Calculate the Np (Barrett n' value). The RSA_CalcNp() API expects
192 * N in LE format. Hence reverse N into a temporary buffer `RevN`.
193 */
194 UTIL_ReverseMemCopy((uint8_t *)RevN, (uint8_t *)pk.N, sizeof(RevN));
195
196 RSA_CalcNp((uintptr_t)PLAT_CRYPTOCELL_BASE, RevN, pk.Np);
197
198 /* Np is in LE format. Reverse it to BE */
199 UTIL_ReverseBuff((uint8_t *)pk.Np, sizeof(pk.Np));
200
201 /* Get the signature (bitstring) */
202 p = sig_ptr;
203 end = p + sig_len;
204 rc = mbedtls_asn1_get_bitstring_null(&p, end, &len);
205 if (rc != 0)
206 return CRYPTO_ERR_SIGNATURE;
207
208 if (len != RSA_MOD_SIZE_IN_BYTES || ((p + len) > end))
209 return CRYPTO_ERR_SIGNATURE;
210
211 /*
212 * The signature is BE format. Convert it to LE before calling
213 * CCSbVerifySignature().
214 */
215 UTIL_ReverseMemCopy((uint8_t *)signature.sig, p, RSA_MOD_SIZE_IN_BYTES);
216
217 /*
218 * CryptoCell utilises DMA internally to transfer data. Flush the data
219 * from caches.
220 */
221 flush_dcache_range((uintptr_t)data_ptr, data_len);
222
223 /* Verify the signature */
224 error = CCSbVerifySignature((uintptr_t)PLAT_CRYPTOCELL_BASE,
225 (uint32_t *)data_ptr, &pk, &signature,
226 data_len, RSA_PSS_2048);
227 if (error != CC_OK)
228 return CRYPTO_ERR_SIGNATURE;
229
230 /* Signature verification success */
231 return CRYPTO_SUCCESS;
232 }
233
234 /*
235 * Match a hash
236 *
237 * Digest info is passed in DER format following the ASN.1 structure detailed
238 * above.
239 */
verify_hash(void * data_ptr,unsigned int data_len,void * digest_info_ptr,unsigned int digest_info_len)240 static int verify_hash(void *data_ptr, unsigned int data_len,
241 void *digest_info_ptr, unsigned int digest_info_len)
242 {
243 mbedtls_asn1_buf hash_oid, params;
244 mbedtls_md_type_t md_alg;
245 uint8_t *p, *end, *hash;
246 CCHashResult_t pubKeyHash;
247 size_t len;
248 int rc;
249 CCError_t error;
250
251 /* Digest info should be an MBEDTLS_ASN1_SEQUENCE */
252 p = digest_info_ptr;
253 end = p + digest_info_len;
254 rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED |
255 MBEDTLS_ASN1_SEQUENCE);
256 if (rc != 0)
257 return CRYPTO_ERR_HASH;
258
259 /* Get the hash algorithm */
260 rc = mbedtls_asn1_get_alg(&p, end, &hash_oid, ¶ms);
261 if (rc != 0)
262 return CRYPTO_ERR_HASH;
263
264 rc = mbedtls_oid_get_md_alg(&hash_oid, &md_alg);
265 if (rc != 0)
266 return CRYPTO_ERR_HASH;
267 /* Verify that hash algorithm is SHA256 */
268 if (md_alg != MBEDTLS_MD_SHA256)
269 return CRYPTO_ERR_HASH;
270
271 /* Hash should be octet string type */
272 rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OCTET_STRING);
273 if (rc != 0)
274 return CRYPTO_ERR_HASH;
275
276 /* Length of hash must match the algorithm's size */
277 if (len != HASH_RESULT_SIZE_IN_BYTES)
278 return CRYPTO_ERR_HASH;
279
280 /*
281 * CryptoCell utilises DMA internally to transfer data. Flush the data
282 * from caches.
283 */
284 flush_dcache_range((uintptr_t)data_ptr, data_len);
285
286 hash = p;
287 error = SBROM_CryptoHash((uintptr_t)PLAT_CRYPTOCELL_BASE,
288 (uintptr_t)data_ptr, data_len, pubKeyHash);
289 if (error != CC_OK)
290 return CRYPTO_ERR_HASH;
291
292 rc = memcmp(pubKeyHash, hash, HASH_RESULT_SIZE_IN_BYTES);
293 if (rc != 0)
294 return CRYPTO_ERR_HASH;
295
296 return CRYPTO_SUCCESS;
297 }
298
299 /*
300 * Register crypto library descriptor
301 */
302 REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash);
303
304
305