1 /* 2 * Copyright (c) 2013, Google Inc. 3 * 4 * SPDX-License-Identifier: GPL-2.0+ 5 */ 6 7 #include "mkimage.h" 8 #include <stdio.h> 9 #include <string.h> 10 #include <image.h> 11 #include <time.h> 12 #include <openssl/rsa.h> 13 #include <openssl/pem.h> 14 #include <openssl/err.h> 15 #include <openssl/ssl.h> 16 #include <openssl/evp.h> 17 18 #if OPENSSL_VERSION_NUMBER >= 0x10000000L 19 #define HAVE_ERR_REMOVE_THREAD_STATE 20 #endif 21 22 static int rsa_err(const char *msg) 23 { 24 unsigned long sslErr = ERR_get_error(); 25 26 fprintf(stderr, "%s", msg); 27 fprintf(stderr, ": %s\n", 28 ERR_error_string(sslErr, 0)); 29 30 return -1; 31 } 32 33 /** 34 * rsa_get_pub_key() - read a public key from a .crt file 35 * 36 * @keydir: Directory containins the key 37 * @name Name of key file (will have a .crt extension) 38 * @rsap Returns RSA object, or NULL on failure 39 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 40 */ 41 static int rsa_get_pub_key(const char *keydir, const char *name, RSA **rsap) 42 { 43 char path[1024]; 44 EVP_PKEY *key; 45 X509 *cert; 46 RSA *rsa; 47 FILE *f; 48 int ret; 49 50 *rsap = NULL; 51 snprintf(path, sizeof(path), "%s/%s.crt", keydir, name); 52 f = fopen(path, "r"); 53 if (!f) { 54 fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n", 55 path, strerror(errno)); 56 return -EACCES; 57 } 58 59 /* Read the certificate */ 60 cert = NULL; 61 if (!PEM_read_X509(f, &cert, NULL, NULL)) { 62 rsa_err("Couldn't read certificate"); 63 ret = -EINVAL; 64 goto err_cert; 65 } 66 67 /* Get the public key from the certificate. */ 68 key = X509_get_pubkey(cert); 69 if (!key) { 70 rsa_err("Couldn't read public key\n"); 71 ret = -EINVAL; 72 goto err_pubkey; 73 } 74 75 /* Convert to a RSA_style key. */ 76 rsa = EVP_PKEY_get1_RSA(key); 77 if (!rsa) { 78 rsa_err("Couldn't convert to a RSA style key"); 79 goto err_rsa; 80 } 81 fclose(f); 82 EVP_PKEY_free(key); 83 X509_free(cert); 84 *rsap = rsa; 85 86 return 0; 87 88 err_rsa: 89 EVP_PKEY_free(key); 90 err_pubkey: 91 X509_free(cert); 92 err_cert: 93 fclose(f); 94 return ret; 95 } 96 97 /** 98 * rsa_get_priv_key() - read a private key from a .key file 99 * 100 * @keydir: Directory containins the key 101 * @name Name of key file (will have a .key extension) 102 * @rsap Returns RSA object, or NULL on failure 103 * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL) 104 */ 105 static int rsa_get_priv_key(const char *keydir, const char *name, RSA **rsap) 106 { 107 char path[1024]; 108 RSA *rsa; 109 FILE *f; 110 111 *rsap = NULL; 112 snprintf(path, sizeof(path), "%s/%s.key", keydir, name); 113 f = fopen(path, "r"); 114 if (!f) { 115 fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n", 116 path, strerror(errno)); 117 return -ENOENT; 118 } 119 120 rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path); 121 if (!rsa) { 122 rsa_err("Failure reading private key"); 123 fclose(f); 124 return -EPROTO; 125 } 126 fclose(f); 127 *rsap = rsa; 128 129 return 0; 130 } 131 132 static int rsa_init(void) 133 { 134 int ret; 135 136 ret = SSL_library_init(); 137 if (!ret) { 138 fprintf(stderr, "Failure to init SSL library\n"); 139 return -1; 140 } 141 SSL_load_error_strings(); 142 143 OpenSSL_add_all_algorithms(); 144 OpenSSL_add_all_digests(); 145 OpenSSL_add_all_ciphers(); 146 147 return 0; 148 } 149 150 static void rsa_remove(void) 151 { 152 CRYPTO_cleanup_all_ex_data(); 153 ERR_free_strings(); 154 #ifdef HAVE_ERR_REMOVE_THREAD_STATE 155 ERR_remove_thread_state(NULL); 156 #else 157 ERR_remove_state(0); 158 #endif 159 EVP_cleanup(); 160 } 161 162 static int rsa_sign_with_key(RSA *rsa, struct checksum_algo *checksum_algo, 163 const struct image_region region[], int region_count, 164 uint8_t **sigp, uint *sig_size) 165 { 166 EVP_PKEY *key; 167 EVP_MD_CTX *context; 168 int size, ret = 0; 169 uint8_t *sig; 170 int i; 171 172 key = EVP_PKEY_new(); 173 if (!key) 174 return rsa_err("EVP_PKEY object creation failed"); 175 176 if (!EVP_PKEY_set1_RSA(key, rsa)) { 177 ret = rsa_err("EVP key setup failed"); 178 goto err_set; 179 } 180 181 size = EVP_PKEY_size(key); 182 sig = malloc(size); 183 if (!sig) { 184 fprintf(stderr, "Out of memory for signature (%d bytes)\n", 185 size); 186 ret = -ENOMEM; 187 goto err_alloc; 188 } 189 190 context = EVP_MD_CTX_create(); 191 if (!context) { 192 ret = rsa_err("EVP context creation failed"); 193 goto err_create; 194 } 195 EVP_MD_CTX_init(context); 196 if (!EVP_SignInit(context, checksum_algo->calculate_sign())) { 197 ret = rsa_err("Signer setup failed"); 198 goto err_sign; 199 } 200 201 for (i = 0; i < region_count; i++) { 202 if (!EVP_SignUpdate(context, region[i].data, region[i].size)) { 203 ret = rsa_err("Signing data failed"); 204 goto err_sign; 205 } 206 } 207 208 if (!EVP_SignFinal(context, sig, sig_size, key)) { 209 ret = rsa_err("Could not obtain signature"); 210 goto err_sign; 211 } 212 EVP_MD_CTX_cleanup(context); 213 EVP_MD_CTX_destroy(context); 214 EVP_PKEY_free(key); 215 216 debug("Got signature: %d bytes, expected %d\n", *sig_size, size); 217 *sigp = sig; 218 *sig_size = size; 219 220 return 0; 221 222 err_sign: 223 EVP_MD_CTX_destroy(context); 224 err_create: 225 free(sig); 226 err_alloc: 227 err_set: 228 EVP_PKEY_free(key); 229 return ret; 230 } 231 232 int rsa_sign(struct image_sign_info *info, 233 const struct image_region region[], int region_count, 234 uint8_t **sigp, uint *sig_len) 235 { 236 RSA *rsa; 237 int ret; 238 239 ret = rsa_init(); 240 if (ret) 241 return ret; 242 243 ret = rsa_get_priv_key(info->keydir, info->keyname, &rsa); 244 if (ret) 245 goto err_priv; 246 ret = rsa_sign_with_key(rsa, info->algo->checksum, region, 247 region_count, sigp, sig_len); 248 if (ret) 249 goto err_sign; 250 251 RSA_free(rsa); 252 rsa_remove(); 253 254 return ret; 255 256 err_sign: 257 RSA_free(rsa); 258 err_priv: 259 rsa_remove(); 260 return ret; 261 } 262 263 /* 264 * rsa_get_params(): - Get the important parameters of an RSA public key 265 */ 266 int rsa_get_params(RSA *key, uint32_t *n0_invp, BIGNUM **modulusp, 267 BIGNUM **r_squaredp) 268 { 269 BIGNUM *big1, *big2, *big32, *big2_32; 270 BIGNUM *n, *r, *r_squared, *tmp; 271 BN_CTX *bn_ctx = BN_CTX_new(); 272 int ret = 0; 273 274 /* Initialize BIGNUMs */ 275 big1 = BN_new(); 276 big2 = BN_new(); 277 big32 = BN_new(); 278 r = BN_new(); 279 r_squared = BN_new(); 280 tmp = BN_new(); 281 big2_32 = BN_new(); 282 n = BN_new(); 283 if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 || 284 !n) { 285 fprintf(stderr, "Out of memory (bignum)\n"); 286 return -ENOMEM; 287 } 288 289 if (!BN_copy(n, key->n) || !BN_set_word(big1, 1L) || 290 !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L)) 291 ret = -1; 292 293 /* big2_32 = 2^32 */ 294 if (!BN_exp(big2_32, big2, big32, bn_ctx)) 295 ret = -1; 296 297 /* Calculate n0_inv = -1 / n[0] mod 2^32 */ 298 if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) || 299 !BN_sub(tmp, big2_32, tmp)) 300 ret = -1; 301 *n0_invp = BN_get_word(tmp); 302 303 /* Calculate R = 2^(# of key bits) */ 304 if (!BN_set_word(tmp, BN_num_bits(n)) || 305 !BN_exp(r, big2, tmp, bn_ctx)) 306 ret = -1; 307 308 /* Calculate r_squared = R^2 mod n */ 309 if (!BN_copy(r_squared, r) || 310 !BN_mul(tmp, r_squared, r, bn_ctx) || 311 !BN_mod(r_squared, tmp, n, bn_ctx)) 312 ret = -1; 313 314 *modulusp = n; 315 *r_squaredp = r_squared; 316 317 BN_free(big1); 318 BN_free(big2); 319 BN_free(big32); 320 BN_free(r); 321 BN_free(tmp); 322 BN_free(big2_32); 323 if (ret) { 324 fprintf(stderr, "Bignum operations failed\n"); 325 return -ENOMEM; 326 } 327 328 return ret; 329 } 330 331 static int fdt_add_bignum(void *blob, int noffset, const char *prop_name, 332 BIGNUM *num, int num_bits) 333 { 334 int nwords = num_bits / 32; 335 int size; 336 uint32_t *buf, *ptr; 337 BIGNUM *tmp, *big2, *big32, *big2_32; 338 BN_CTX *ctx; 339 int ret; 340 341 tmp = BN_new(); 342 big2 = BN_new(); 343 big32 = BN_new(); 344 big2_32 = BN_new(); 345 if (!tmp || !big2 || !big32 || !big2_32) { 346 fprintf(stderr, "Out of memory (bignum)\n"); 347 return -ENOMEM; 348 } 349 ctx = BN_CTX_new(); 350 if (!tmp) { 351 fprintf(stderr, "Out of memory (bignum context)\n"); 352 return -ENOMEM; 353 } 354 BN_set_word(big2, 2L); 355 BN_set_word(big32, 32L); 356 BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */ 357 358 size = nwords * sizeof(uint32_t); 359 buf = malloc(size); 360 if (!buf) { 361 fprintf(stderr, "Out of memory (%d bytes)\n", size); 362 return -ENOMEM; 363 } 364 365 /* Write out modulus as big endian array of integers */ 366 for (ptr = buf + nwords - 1; ptr >= buf; ptr--) { 367 BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */ 368 *ptr = cpu_to_fdt32(BN_get_word(tmp)); 369 BN_rshift(num, num, 32); /* N = N/B */ 370 } 371 372 ret = fdt_setprop(blob, noffset, prop_name, buf, size); 373 if (ret) { 374 fprintf(stderr, "Failed to write public key to FIT\n"); 375 return -ENOSPC; 376 } 377 free(buf); 378 BN_free(tmp); 379 BN_free(big2); 380 BN_free(big32); 381 BN_free(big2_32); 382 383 return ret; 384 } 385 386 int rsa_add_verify_data(struct image_sign_info *info, void *keydest) 387 { 388 BIGNUM *modulus, *r_squared; 389 uint32_t n0_inv; 390 int parent, node; 391 char name[100]; 392 int ret; 393 int bits; 394 RSA *rsa; 395 396 debug("%s: Getting verification data\n", __func__); 397 ret = rsa_get_pub_key(info->keydir, info->keyname, &rsa); 398 if (ret) 399 return ret; 400 ret = rsa_get_params(rsa, &n0_inv, &modulus, &r_squared); 401 if (ret) 402 return ret; 403 bits = BN_num_bits(modulus); 404 parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME); 405 if (parent == -FDT_ERR_NOTFOUND) { 406 parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME); 407 if (parent < 0) { 408 fprintf(stderr, "Couldn't create signature node: %s\n", 409 fdt_strerror(parent)); 410 return -EINVAL; 411 } 412 } 413 414 /* Either create or overwrite the named key node */ 415 snprintf(name, sizeof(name), "key-%s", info->keyname); 416 node = fdt_subnode_offset(keydest, parent, name); 417 if (node == -FDT_ERR_NOTFOUND) { 418 node = fdt_add_subnode(keydest, parent, name); 419 if (node < 0) { 420 fprintf(stderr, "Could not create key subnode: %s\n", 421 fdt_strerror(node)); 422 return -EINVAL; 423 } 424 } else if (node < 0) { 425 fprintf(stderr, "Cannot select keys parent: %s\n", 426 fdt_strerror(node)); 427 return -ENOSPC; 428 } 429 430 ret = fdt_setprop_string(keydest, node, "key-name-hint", 431 info->keyname); 432 if (!ret) 433 ret = fdt_setprop_u32(keydest, node, "rsa,num-bits", bits); 434 if (!ret) 435 ret = fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv); 436 if (!ret) { 437 ret = fdt_add_bignum(keydest, node, "rsa,modulus", modulus, 438 bits); 439 } 440 if (!ret) { 441 ret = fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared, 442 bits); 443 } 444 if (!ret) { 445 ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP, 446 info->algo->name); 447 } 448 if (info->require_keys) { 449 ret = fdt_setprop_string(keydest, node, "required", 450 info->require_keys); 451 } 452 BN_free(modulus); 453 BN_free(r_squared); 454 if (ret) 455 return ret == FDT_ERR_NOSPACE ? -ENOSPC : -EIO; 456 457 return 0; 458 } 459